Science.gov

Sample records for low-temperature proton irradiation

  1. Studies of proton-irradiated SO2 at low temperatures Implications for Io

    NASA Astrophysics Data System (ADS)

    Moore, M. H.

    1984-07-01

    The infrared absorption spectrum from 3.3 to 27 microns of SO2 ice films has been measured at 20 and 88 K before and after 1-MeV proton irradiation. The radiation flux was chosen to simulate the estimated flux of Jovian magnetospheric 1-MeV protons incident on Io. After irradiation, SO3 is identified as the dominant molecule synthesized in the SO2 ice. This is also the case after irradiation of composite samples of SO2 with sulfur or disulfites. Darkening was observed in irradiated SO2 ice and in irradiated S8 pellets. Photometric and spectral measurements of the thermoluminescence of irradiated SO2 have been made during warming. The spectrum appears as a broad band with a maximum at 4450 A. Analysis of the luminescence data suggests that at Ionian temperatures irradiated SO2 ice would not be a dominant contributor to posteclipse brightening phenomena. After warming to room temperature, a form of SO3 remains along with a sulfate and S8. Based on these experiments, it is reasonable to propose that small amounts of SO3 may exist on the surface of Io as a result of irradiation synthesis in SO2 frosts.

  2. Studies of proton-irradiated SO2 at low temperatures Implications for Io

    NASA Technical Reports Server (NTRS)

    Moore, M. H.

    1984-01-01

    The infrared absorption spectrum from 3.3 to 27 microns of SO2 ice films has been measured at 20 and 88 K before and after 1-MeV proton irradiation. The radiation flux was chosen to simulate the estimated flux of Jovian magnetospheric 1-MeV protons incident on Io. After irradiation, SO3 is identified as the dominant molecule synthesized in the SO2 ice. This is also the case after irradiation of composite samples of SO2 with sulfur or disulfites. Darkening was observed in irradiated SO2 ice and in irradiated S8 pellets. Photometric and spectral measurements of the thermoluminescence of irradiated SO2 have been made during warming. The spectrum appears as a broad band with a maximum at 4450 A. Analysis of the luminescence data suggests that at Ionian temperatures irradiated SO2 ice would not be a dominant contributor to posteclipse brightening phenomena. After warming to room temperature, a form of SO3 remains along with a sulfate and S8. Based on these experiments, it is reasonable to propose that small amounts of SO3 may exist on the surface of Io as a result of irradiation synthesis in SO2 frosts.

  3. Minimizing material damage using low temperature irradiation

    NASA Astrophysics Data System (ADS)

    Craven, E.; Hasanain, F.; Winters, M.

    2012-08-01

    Scientific advancements in healthcare driven both by technological breakthroughs and an aging and increasingly obese population have lead to a changing medical device market. Complex products and devices are being developed to meet the demands of leading edge medical procedures. Specialized materials in these medical devices, including pharmaceuticals and biologics as well as exotic polymers present a challenge for radiation sterilization as many of these components cannot withstand conventional irradiation methods. The irradiation of materials at dry ice temperatures has emerged as a technique that can be used to decrease the radiation sensitivity of materials. The purpose of this study is to examine the effect of low temperature irradiation on a variety of polymer materials, and over a range of temperatures from 0 °C down to -80 °C. The effectiveness of microbial kill is also investigated under each of these conditions. The results of the study show that the effect of low temperature irradiation is material dependent and can alter the balance between crosslinking and chain scission of the polymer. Low temperatures also increase the dose required to achieve an equivalent microbiological kill, therefore dose setting exercises must be performed under the environmental conditions of use.

  4. Mechanical-property changes of structural composite materials after low-temperature proton irradiation: Implications for use in SSC magnet systems

    SciTech Connect

    Morena, J.; Snead, C.L. Jr.; Czajkowski, C.; Skaritka, J.

    1993-07-01

    Longterm physical, mechanical, electrical, and other properties of advanced composites, plastics, and other polymer materials are greatly affected by high-energy proton, neutron, electron, and gamma radiation. The effects of high-energy particles on materials is a critical design parameter to consider when choosing polymeric structural, nonstructural, and elastomeric matrix resin systems. Polymer materials used for filled resins, laminates, seals, gaskets, coatings, insulation and other nonmetallic components must be chosen carefully, and reference data viewed with caution. Most reference data collected in the high-energy physics community to date reflects material property degradation using other than proton irradiations. In most instances, the data were collected for room-temperature irradiations, not 4.2 K or other cryogenic temperatures, and at doses less than 10{sup 8}--10{sup 9} Rad. Energetic proton (and the accompanying spallation-product particles) provide good simulation fidelity to the expected radiation fields predicted for the cold-mass regions of the SSC magnets, especially the corrector magnets. The authors present here results for some structural composite materials which were part of a larger irradiation-characterization of polymeric materials for SSC applications.

  5. UV-induced protonation of molecules adsorbed on ice surfaces at low temperature.

    PubMed

    Moon, Eui-Seong; Lee, Chang-Woo; Kim, Joon-Ki; Park, Seong-Chan; Kang, Heon

    2008-05-21

    UV irradiation of ice films adsorbed with methylamine molecules induces protonation of the adsorbate molecules at low temperature (50-130 K). The observation indicates that long-lived protonic defects are created in the ice film by UV light, and they transfer protons to the adsorbate molecules via tunneling mechanism at low temperature. The methylammonium ion formed by proton transfer remains to be stable at the ice surface. It is suggested that this solid-phase protonation might play a significant role in the production of molecular ions in interstellar clouds.

  6. Preliminary Low Temperature Electron Irradiation of Triple Junction Solar Cells

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.; Mueller, Robert L.; Scrivner, Roy L.; Helizon, Roger S.

    2007-01-01

    For many years extending solar power missions far from the sun has been a challenge not only due to the rapid falloff in solar intensity (intensity varies as inverse square of solar distance) but also because some of the solar cells in an array may exhibit a LILT (low intensity low temperature) degradation that reduces array performance. Recent LILT tests performed on commercial triple junction solar cells have shown that high performance can be obtained at solar distances as great as approx. 5 AU1. As a result, their use for missions going far from the sun has become very attractive. One additional question that remains is whether the radiation damage experienced by solar cells under low temperature conditions will be more severe than when measured during room temperature radiation tests where thermal annealing may take place. This is especially pertinent to missions such as the New Frontiers mission Juno, which will experience cell irradiation from the trapped electron environment at Jupiter. Recent testing2 has shown that low temperature proton irradiation (10 MeV) produces cell degradation results similar to room temperature irradiations and that thermal annealing does not play a factor. Although it is suggestive to propose the same would be observed for low temperature electron irradiations, this has not been verified. JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature. A fluence of 1E15 1MeV electrons was

  7. Thermal conductivity degradation of graphites irradiated at low temperature

    SciTech Connect

    Snead, L.L.; Burchell, T.D.

    1995-04-01

    The objective of this work is to study the thermal conductivity degradation of new, high thermal conductivity graphites and to compare these results to more standard graphites irradiated at low temperatures. Several graphites and graphite composites (C/C`s) have been irradiated near 150{degree}C and at fluences up to a displacement level of 0.24 dpa. The materials ranged in unirradiated room temperature thermal conductivity of these materials varied from 114 W/m-K for H-451 isotropic graphite, to 670 W/m-K for unidirectional FMI-1D C/C composite. At the irradiation temperature a saturation reduction in thermal conductivity was seen to occur at displacement levels of approximately 0.1 dpa. All materials were seen to degrade to approximately 10 to 14 % of their original thermal conductivity after irradiation. The effect of post irradiation annealing on the thermal conductivity was also studied.

  8. Preliminary low temperature electron irradiation of triple junction solar cells

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.; Mueller, Robert L.; Scrivner, Roy L.; Helizon, Roger S.

    2005-01-01

    JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature.

  9. Low-temperature electron irradiation and annealing in pure magnesium

    SciTech Connect

    Simester, J.H.

    1982-01-01

    In this study of magnesium after 1.0 MeV electron irradiations at 1.55/sup 0/K, it has been observed that the damage production rate in Mg is (3.57 +- 0.03) x 10/sup -26/ ..cap omega..cm/(e/sup -/ cm/sup 2/). There is no evidence for thermal annealing up to 4/sup 0/K. The low temperature recovery in magnesium is found to consist of two broad substages between 4 to 14/sup 0/K, both of which exhibit evidence for correlated and uncorrelated recovery processes. The two substages are found to have very different frequency factors for annealing, and there is evidence that the recovery processes in the second substage are influenced by those in the first. A model for recovery is proposed using the split configuration in the plane which explains the first substage as being due to interstitial migration in the basal plane and the second to migration perpendicular to the plane.

  10. Dose dependence of mechanical properties in tantalum and tantalum alloys after low temperature irradiation

    SciTech Connect

    Byun, Thak Sang

    2008-01-01

    The dose dependence of mechanical properties was investigated for tantalum and tantalum alloys after low temperature irradiation. Miniature tensile specimens of three pure tantalum metals, ISIS Ta, Aesar Ta1, Aesar Ta2, and one tantalum alloy, Ta-1W, were irradiated by neutrons in the High Flux Isotope Reactor (HFIR) at ORNL to doses ranging from 0.00004 to 0.14 displacements per atom (dpa) in the temperature range 60 C 100 oC. Also, two tantalum-tungsten alloys, Ta-1W and Ta-10W, were irradiated by protons and spallation neutrons in the LANSCE facility at LANL to doses ranging from 0.7 to 7.5 dpa and from 0.7 to 25.2 dpa, respectively, in the temperature range 50 C 160 oC. Tensile tests were performed at room temperature and at 250oC at nominal strain rates of about 10-3 s-1. All neutron-irradiated materials underwent progressive irradiation hardening and loss of ductility with increasing dose. The ISIS Ta experienced embrittlement at 0.14 dpa, while the other metals retained significant necking ductility. Such a premature embrittlement in ISIS Ta is believed to be because of high initial oxygen concentrations picked up during a pre-irradiation anneal. The Ta-1W and Ta-10W specimens irradiated in spallation condition experienced prompt necking at yield since irradiation doses for those specimens were high ( 0.7 dpa). At the highest dose, 25.2 dpa, the Ta-10W alloy specimen broke with little necking strain. Among the test materials, the Ta-1W alloy displayed the best combination of strength and ductility. The plastic instability stress and true fracture stress were nearly independent of dose. Increasing test temperature decreased strength and delayed the onset of necking at yield.

  11. Low temperature oxidation of crystalline silicon using excimer laser irradiation

    NASA Astrophysics Data System (ADS)

    Nayar, Vishal; Boyd, Ian W.; Goodall, F. N.; Arthur, G.

    In this paper we present a study of ultra-violet laser oxidation of silicon at low temperature (< 650° C), using both 249 and 193 nm radiation. Calculation of the surface temperature rise during the laser pulses suggests that non-thermal oxidation mechanisms are present. In addition to the growth of planar thin oxides over macroscopic areas, a new technique for selectivity oxidising silicon by direct image projection, i.e., direct growth lithography (DGL) is also preliminarily presented.

  12. Low Temperature Irradiation Embrittlement of Reactor Pressure Vessel Steels

    SciTech Connect

    Wang, Jy-An John

    2015-08-01

    The embrittlement trend curve development project for HFIR reactor pressure vessel (RPV) steels was carried out with three major tasks. Which are (1) data collection to match that used in HFIR steel embrittlement trend published in 1994 Journal Nuclear Material by Remec et. al, (2) new embrittlement data of A212B steel that are not included in earlier HFIR RPV trend curve, and (3) the adjustment of nil-ductility-transition temperature (NDTT) shift data with the consideration of the irradiation temperature effect. An updated HFIR RPV steel embrittlement trend curve was developed, as described below. NDTT( C) = 23.85 log(x) + 203.3 log (x) + 434.7, with 2- uncertainty of 34.6 C, where parameter x is referred to total dpa. The developed update HFIR RPV embrittlement trend curve has higher embrittlement rate compared to that of the trend curve developed in 1994.

  13. Deformation in metals after low temperature irradiation: Part II - Irradiation hardening, strain hardening, and stress ratios

    SciTech Connect

    Byun, Thak Sang; Li, Meimei

    2008-03-01

    Effects of irradiation at temperatures 200oC on tensile stress parameters are analyzed for dozens of bcc, fcc, and hcp pure metals and alloys, focusing on irradiation hardening, strain hardening, and relationships between the true stress parameters. Similar irradiation-hardening rates are observed for all the metals irrespective of crystal type; typically, the irradiation-hardening rates are large, in the range 100 - 1000 GPa/dpa, at the lowest dose of <0.0001 dpa and decrease with dose to a few tens of MPa/dpa or less at about 10 dpa. However, average irradiation-hardening rates over the dose range of 0 dpa − (the dose to plastic instability at yield) are considerably lower for stainless steels due to their high uniform ductility. It is shown that whereas low temperature irradiation increases the yield stress, it does not significantly change the strain-hardening rate of metallic materials; it decreases the fracture stress only when non-ductile failure occurs. Such dose independence in strain hardening behavior results in strong linear relationships between the true stress parameters. Average ratios of plastic instability stress to unirradiated yield stress are about 1.4, 3.9, and 1.3 for bcc metals (and precipitation hardened IN718 alloy), annealed fcc metals (and pure Zr), and Zr-4 alloy, respectively. Ratios of fracture stress to plastic instability stress are calculated to be 2.2, 1.7, and 2.1, respectively. Comparison of these values confirms that the annealed fcc metals and other soft metals have larger uniform ductility but smaller necking ductility when compared to other materials.

  14. Low-temperature radiation cracking of heavy oil under continuous and pulse electron irradiation

    NASA Astrophysics Data System (ADS)

    Zaikin, Yuriy A.

    2016-05-01

    The dependence of the chain reaction parameters on the conditions of pulse and continuous electron irradiation is analyzed for the case of low-temperature radiation cracking of heavy oils. The specificity of kinetics and yields of light products after radiation cracking are considered in the cases of continuous and pulse irradiation. Theoretical calculations are compared with experimental data on electron irradiation of heavy oil in different conditions.

  15. Radiation-induced intermediates in irradiated glassy ionic liquids at low temperature

    NASA Astrophysics Data System (ADS)

    Saenko, Elizaveta V.; Lukianova, Mariia A.; Shiryaeva, Ekaterina S.; Takahashi, Kenji; Feldman, Vladimir I.

    2016-07-01

    The primary radiation-induced processes in irradiated low-temperature pyrrolidinium- and piperidinium-type ionic liquids were investigated by EPR and optical absorption spectroscopy. A narrow singlet signal in the EPR spectra of irradiated ionic liquids was attributed to the physically stabilized electron. Broad absorption band in visible region was ascribed to "hole" species. Aromatic scavengers react with "hole" species in glassy irradiated ionic liquids at 77 K.

  16. Phosphorus-doped glass proton exchange membranes for low temperature direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Prakash, Shruti; Mustain, William E.; Park, SeongHo; Kohl, Paul A.

    Phosphorus-doped silicon dioxide thin films were used as ion exchange membranes in low temperature proton exchange membrane fuel cells. Phosphorus-doped silicon dioxide glass (PSG) was deposited via plasma-enhanced chemical vapor deposition (PECVD). The plasma deposition of PSG films allows for low temperature fabrication that is compatible with current microelectronic industrial processing. SiH 4, PH 3 and N 2O were used as the reactant gases. The effect of plasma deposition parameters, substrate temperature, RF power, and chamber pressure, on the ionic conductivity of the PSG films is elucidated. PSG conductivities as high as 2.54 × 10 -4 S cm -1 were realized, which is 250 times higher than the conductivity of pure SiO 2 films (1 × 10 -6 S cm -1) under identical deposition conditions. The higher conductivity films were deposited at low temperature, moderate pressure, limited reactant gas flow rate, and high RF power.

  17. Composite electrolyte with proton conductivity for low-temperature solid oxide fuel cell

    SciTech Connect

    Raza, Rizwan; Ahmed, Akhlaq; Akram, Nadeem; Saleem, Muhammad; Niaz Akhtar, Majid; Ajmal Khan, M.; Abbas, Ghazanfar; Alvi, Farah; Yasir Rafique, M.; Sherazi, Tauqir A.; Shakir, Imran; Mohsin, Munazza; Javed, Muhammad Sufyan; Zhu, Bin E-mail: zhubin@hubu.edu.cn

    2015-11-02

    In the present work, cost-effective nanocomposite electrolyte (Ba-SDC) oxide is developed for efficient low-temperature solid oxide fuel cells (LTSOFCs). Analysis has shown that dual phase conduction of O{sup −2} (oxygen ions) and H{sup +} (protons) plays a significant role in the development of advanced LTSOFCs. Comparatively high proton ion conductivity (0.19 s/cm) for LTSOFCs was achieved at low temperature (460 °C). In this article, the ionic conduction behaviour of LTSOFCs is explained by carrying out electrochemical impedance spectroscopy measurements. Further, the phase and structure analysis are investigated by X-ray diffraction and scanning electron microscopy techniques. Finally, we achieved an ionic transport number of the composite electrolyte for LTSOFCs as high as 0.95 and energy and power density of 90% and 550 mW/cm{sup 2}, respectively, after sintering the composite electrolyte at 800 °C for 4 h, which is promising. Our current effort toward the development of an efficient, green, low-temperature solid oxide fuel cell with the incorporation of high proton conductivity composite electrolyte may open frontiers in the fields of energy and fuel cell technology.

  18. Irradiation of Frozen Solutions of Ferrous Sulphate as Dosimeter for Low Temperature Irradiations

    NASA Astrophysics Data System (ADS)

    Sánchez-Mejorada, G.; Frias, D.

    2006-09-01

    A theoretical model is presented for the evaluation of the energy transferred during the interaction of high energy radiation with icy bodies. Numerical simulations of the chemical reaction system reproduce the behavior of the icy systems (frozen solution of iron salts) after its interaction with the gamma radiation. Simulation experiments of extraterrestrial bodies are useful for space research, where low temperature dosimetry is necessary, especially in trips with humans or in the International Space Station (ISS) where humans are exposed to high radiation doses. The results showed that theoretical model applied for the irradiated system for different doses (from 10 to 2500Gy) and at different temperature (from 77 to 298 °K). The system under study was frozen solutions of iron salts and were analyzed (after Melting) by UV-spectroscopy. The systems were irradiates with gamma radiation. It is also shown that the response of the system is a function of the temperature and it was linear with as a function of dose.

  19. Effects of irradiation at low temperature on V-4Cr-4Ti

    SciTech Connect

    Alexander, D.J.; Snead, L.L.; Zinkle, S.J.

    1996-10-01

    Irradiation at low temperatures (100 to 275{degrees}C) to 0.5 dpa causes significant embrittlement and changes in the subsequent room temperature tensile properties of V-4Cr-4Ti. The yield strength and microhardness at room temperature increase with increasing irradiation temperature. The tensile flow properties at room temperature show large increases in strength and a complete loss of work hardening capacity with no uniform ductility. Embrittlement, as measured by an increase in the ductile-to-brittle transition temperature, increases with increasing irradiation temperature, at least up to 275{degrees}C. This embrittlement is not due to pickup of O or other interstitial solutes during the irradiation.

  20. Temperature dependence of the deformation behavior of 316 stainless steel after low temperature neutron irradiation

    SciTech Connect

    Pawel-Robertson, J.E.; Rowcliffe, A.F.; Grossbeck, M.L.

    1996-10-01

    The effects of low temperature neutron irradiation on the tensile behavior of 316 stainless steel have been investigated. A single heat of solution annealed 316 was irradiated to 7 and 18 dpa at 60, 200, 330, and 400{degrees}C. The tensile properties as a function of dose and as a function of temperature were examined. Large changes in yield strength, deformation mode, strain to necking, and strain hardening capacity were seen in this irradiation experiment. The magnitudes of the changes are dependent on both irradiation temperature and neutron dose. Irradiation can more than triple the yield strength over the unirradiated value and decrease the strain to necking (STN) to less than 0.5% under certain conditions. A maximum increase in yield strength and a minimum in the STN occur after irradiation at 330{degrees}C but the failure mode remains ductile.

  1. The influence of low temperature on gamma-ray irradiated permanent magnets.

    PubMed

    Han, Young Chul; Cha, Hyun Gil; Kim, Chang Woo; Ji, Eun Sun; Kim, Young Hwan; Kang, Dong In; Kang, Young Soo

    2009-12-01

    The temperature effect on the magnetic property of gamma-ray irradiated Nd-Fe-B and Sr-Ferrite magnets has been investigated. When the permanent magnets are exposed to gamma-ray, it's magnetic and other related properties are declined with degree of dose. The decreased magnetic property by gamma-ray irradiation at low temperature is similar with the result of magnet at high temperature. The temperature effect on the gamma-ray irradiation at exposed moment is also regarded as one of the important parameters for the reduced magnetic properties. The gamma-irradiation at low temperature was carried out at 195 K, and the changed properties of two kinds of magnets before and after gamma-irradiation were comparatively studied. The increased demagnetization of the magnets were studied by Hall probe. And changed Curie temperature and micro-crystal structure of each permanent magnet by gamma-ray irradiation has been also studied. Moreover the strong and broad single line shape of ESR signal in the resonance magnetic field is attributed to unpaired electron of Fe2+ in the sample by the effect of gamma-ray irradiation.

  2. Proton irradiation and endometriosis

    SciTech Connect

    Wood, D.H.; Yochmowitz, M.G.; Salmon, Y.L.; Eason, R.L.; Boster, R.A.

    1983-08-01

    It was found that female rhesus monkeys given single total-body exposures of protons of varying energies developed endometriosis at a frequency significantly higher than that of nonirradiated animals of the same age. The minimum latency period was determined to be 7 years after the proton exposure. The doses and energies of the radiation received by the experimental animals were within the range that could be received by an aircrew member in near-earth orbit during a random solar flare event. It is concluded that endometriosis should be a consideration in assessing the risk of delayed radiation effects in female crew members. 15 references.

  3. Improvement of low-temperature irradiation facility at Kyoto University Reactor (KUR)

    NASA Astrophysics Data System (ADS)

    Okada, M.; Kanazawa, S.; Nozaki, T.; Nakagawa, M.; Atobe, K.; Kuramoto, E.; Matsumura, K.; Sano, T.

    2001-05-01

    The low-temperature irradiation facility at the Kyoto University Reactor (KUR) has been upgraded. Cryogenic power has been increased from 37 W to about 58 W at 10 K, and irradiation temperature has been reduced from 20 to 12 K at 5 MW reactor operating power. The maximum fast-neutron flux after these improvements is about 4.77×10 11 n/n cm -2 s -1. Therefore, the maximum fluence of fast-neutrons at the KUR facility is about 1.3×10 17 n cm -2 for the maximum operating time of 77 h per week.

  4. Readily processed protonic ceramic fuel cells with high performance at low temperatures.

    PubMed

    Duan, Chuancheng; Tong, Jianhua; Shang, Meng; Nikodemski, Stefan; Sanders, Michael; Ricote, Sandrine; Almansoori, Ali; O'Hayre, Ryan

    2015-09-18

    Because of the generally lower activation energy associated with proton conduction in oxides compared to oxygen ion conduction, protonic ceramic fuel cells (PCFCs) should be able to operate at lower temperatures than solid oxide fuel cells (250° to 550°C versus ≥600°C) on hydrogen and hydrocarbon fuels if fabrication challenges and suitable cathodes can be developed. We fabricated the complete sandwich structure of PCFCs directly from raw precursor oxides with only one moderate-temperature processing step through the use of sintering agents such as copper oxide. We also developed a proton-, oxygen-ion-, and electron-hole-conducting PCFC-compatible cathode material, BaCo(0.4)Fe(0.4)Zr(0.1)Y(0.1)O(3-δ) (BCFZY0.1), that greatly improved oxygen reduction reaction kinetics at intermediate to low temperatures. We demonstrated high performance from five different types of PCFC button cells without degradation after 1400 hours. Power densities as high as 455 milliwatts per square centimeter at 500°C on H2 and 142 milliwatts per square centimeter on CH4 were achieved, and operation was possible even at 350°C.

  5. Using gamma irradiation and low temperature on microbial decontamination of red meat in Iran.

    PubMed

    Sedeh, F M; Arbabi, K; Fatolahi, H; Abhari, M

    2007-03-01

    Gamma irradiation can be used as one of the most efficient methods to reduce microorganisms in food. The irradiation of food is used for a number of purposes, including microbiological control, insects control and inhibition of sprouting and delay of senescence of living food. The aim of this study was to study effects of gamma irradiation, refrigeration and frozen storage as the combination process for improvement of red meat shelf-life. The bovine meat samples were treated with 0, 0.5, 1, 2 and 3 kGy of gamma irradiation and kept in refrigerator for 3 weeks and in freezer for 8 months. The control and irradiated samples were stored at 4-7°C and at -18°C for refrigeration and frozen storage, respectively; and microbial and chemical analyze was done at 1 week and 2 months intervals. In this study the optimum dose of gamma radiation in order to decrease the total count of Mesophilic bacteria, Coliforms, Staphylococcus aureus and especially for elimination of Salmonella was obtained at 3 kGy. Microbial analysis indicated that irradiation and storage at low temperature had a significant effect on the reduction of microbial loads. There was no significant difference in chemical characteristics during freezing storage in bovine meat. Also, irradiated meat samples (3 kGy) were stored in 4-7°C for 14 days, compared to 3 days for non irradiated samples. PMID:23100643

  6. In Situ Irradiation and Measurement of Triple Junction Solar Cells at Low Intensity, Low Temperature (LILT) Conditions

    NASA Technical Reports Server (NTRS)

    Harris, R.D.; Imaizumi, M.; Walters, R.J.; Lorentzen, J.R.; Messenger, S.R.; Tischler, J.G.; Ohshima, T.; Sato, S.; Sharps, P.R.; Fatemi, N.S.

    2008-01-01

    The performance of triple junction InGaP/(In)GaAs/Ge space solar cells was studied following high energy electron irradiation at low temperature. Cell characterization was carried out in situ at the irradiation temperature while using low intensity illumination, and, as such, these conditions reflect those found for deep space, solar powered missions that are far from the sun. Cell characterization consisted of I-V measurements and quantum efficiency measurements. The low temperature irradiations caused substantial degradation that differs in some ways from that seen after room temperature irradiations. The short circuit current degrades more at low temperature while the open circuit voltage degrades more at room temperature. A room temperature anneal after the low temperature irradiation produced a substantial recovery in the degradation. Following irradiation at both temperatures and an extended room temperature anneal, quantum efficiency measurement suggests that the bulk of the remaining damage is in the (In)GaAs sub-cell

  7. Proton irradiation and endometriosis

    SciTech Connect

    Wood, D.H.; Yochmowitz, M.G.; Salmon, Y.L.; Eason, R.L.; Boster, R.A.

    1983-08-01

    Female rhesus monkeys given single total-body exposures of protons of varying energies developed endometriosis at a frequency significantly higher than that of nonirradiated animals of the same age. The minimum latency period was 7 years after exposure. The doses and energies of the radiation received were within the range that could be received by an aircrew member in near-earth orbit during a random solar flare event, leading to the conclusion that endometriosis should be a consideration in assessing the risk of delayed radiation effects in female crewmembers.

  8. Damage structure of austenitic stainless steel 316LN irradiated at low temperature in HFIR

    SciTech Connect

    Hashimoto, N.; Robertson, J.P.; Grossbeck, M.L.; Rowcliffe, A.F.; Wakai, E.

    1998-03-01

    TEM disk specimens of austenitic stainless steel 316LN irradiated to damage levels of about 3 dpa at irradiation temperatures of either about 90 C or 250 C have been investigated by using transmission electron microscopy. The irradiation at 90 C and 250 C induced a dislocation loop density of 3.5 {times} 10{sup 22} m{sup {minus}3} and 6.5 {times} 10{sup 22} m{sup {minus}3}, a black dot density of 2.2 {times} 10{sup 23} m{sup {minus}3} and 1.6 {times} 10{sup 23} m{sup {minus}3}, respectively, in the steels, and a high density (<1 {times} 10{sup 22} m{sup {minus}3}) of precipitates in matrix. Cavities could be observed in the specimens after the irradiation. It is suggested that the dislocation loops, the black dots, and the precipitates cause irradiation hardening, an increase in the yield strength and a decrease in the uniform elongation, in the 316LN steel irradiated at low temperature.

  9. Silicon solar cell characterization at low temperatures and low illumination as a function of particulate irradiation

    NASA Technical Reports Server (NTRS)

    Whitaker, A. F.; Little, S. A.; Peacock, C. L., Jr.

    1983-01-01

    Various configurations of back surface reflector silicon solar cells including small (2 x 2) cm and large (approx. 6 x 6) cm cells with conventional and wraparound contacts were subjected to 1 MeV electron irradiation and characterized under both Earth orbital and deep space conditions of temperatures and illuminations. Current-Voltage (I-V) data were generated from +65 C to -150 C and at incident illuminations from 135.3 mW/sq cm to 5.4 mW/sq cm for these cells. Degradation in cell performance which is manifested only under deep space conditions is emphasized. In addition, the effect of particle irradiation on the high temperature and high intensity and low temperature and low intensity performance of the cells is described. The cells with wraparound contacts were found to have lower efficiencies at Earth orbital conditions than the cells with conventional contacts.

  10. Low-temperature synthesis of allyl dimethylamine by selective heating under microwave irradiation used for water treatment

    NASA Astrophysics Data System (ADS)

    Tian, Binghui; Luan, Zhaokun; Li, Mingming

    2005-08-01

    Low-temperature synthesis of allyl dimethylamine (ADA) by selective heating under microwave irradiation (MI) used for water treatment is investigated. The effect of MI, ultrasound irradiation (UI) and conventional heating on yield of ADA, reaction time and the flocculation efficiency of polydiallyl dimethylammunion chloride (PDADMAC) prepared form ADA were studied. The results show that by selective heating at low temperature, MI not only increases yield of ADA and reduces reaction time, but also greatly enhances the flocculation efficiency of PDADMAC.

  11. Mechanical properties of 1950's vintage 304 stainless steel weldment components after low temperature neutron irradiation

    SciTech Connect

    Sindelar, R.L.; Caskey, G.R. Jr.; Thomas, J.K. ); Hawthorne, J.R.; Hiser, A.L. ); Lott, R.A.; Begley, J.A.; Shogan, R.P. . Science and Technology Center)

    1991-01-01

    The reactor vessels of the nuclear production reactors at the Savannah River Site (SRS) were constructed in the 1950's from Type 304 stainless steel plates welded with Type 308 stainless steel filler using the multipass metal inert gas process. An irradiated mechanical properties database has been developed for the vessel with materials from archival primary coolant system piping irradiated at low temperatures (75 to 150{degrees}C) in the State University of New York at Buffalo reactor (UBR) and the High Flux Isotope Reactor (HFIR) to doses of 0.065 to 2.1 dpa. Fracture toughness, tensile, and Charpy-V impact properties of the weldment components (base, weld, and weld heat-affected-zone (HAZ)) have been measured at temperatures of 25{degrees}C and 125{degrees}C in the L-C and C-L orientations for materials in both the irradiated and unirradiated conditions for companion specimens. Fracture toughness and tensile properties of specimens cut from an SRS reactor vessel sidewall with doses of 0.1 and 0.5 dpa were also measured at temperatures of 25 and 125{degrees}C. The irradiated materials exhibit hardening with loss of work hardenability and a reduction in toughness relative to the unirradiated materials. The HFIR-irradiated materials show an increase in yield strength between about 20% and 190% with a concomitant tensile strength increase between about 15% to 30%. The elastic-plastic fracture toughness parameters and Charpy-V energy absorption both decrease and show only a slight sensitivity to dose. The irradiation-induced decrease in the elastic-plastic fracture toughness (J{sub def} at 1 mm crack extension) is between 20% to 65%; the range of J{sub 1C} values are 72.8 to 366 kJ/m{sup 2} for the irradiated materials. Similarly, Charpy V-notch results show a 40% to 60% decrease in impact energies.

  12. Mechanical properties of 1950`s vintage 304 stainless steel weldment components after low temperature neutron irradiation

    SciTech Connect

    Sindelar, R.L.; Caskey, G.R. Jr.; Thomas, J.K.; Hawthorne, J.R.; Hiser, A.L.; Lott, R.A.; Begley, J.A.; Shogan, R.P.

    1991-12-31

    The reactor vessels of the nuclear production reactors at the Savannah River Site (SRS) were constructed in the 1950`s from Type 304 stainless steel plates welded with Type 308 stainless steel filler using the multipass metal inert gas process. An irradiated mechanical properties database has been developed for the vessel with materials from archival primary coolant system piping irradiated at low temperatures (75 to 150{degrees}C) in the State University of New York at Buffalo reactor (UBR) and the High Flux Isotope Reactor (HFIR) to doses of 0.065 to 2.1 dpa. Fracture toughness, tensile, and Charpy-V impact properties of the weldment components (base, weld, and weld heat-affected-zone (HAZ)) have been measured at temperatures of 25{degrees}C and 125{degrees}C in the L-C and C-L orientations for materials in both the irradiated and unirradiated conditions for companion specimens. Fracture toughness and tensile properties of specimens cut from an SRS reactor vessel sidewall with doses of 0.1 and 0.5 dpa were also measured at temperatures of 25 and 125{degrees}C. The irradiated materials exhibit hardening with loss of work hardenability and a reduction in toughness relative to the unirradiated materials. The HFIR-irradiated materials show an increase in yield strength between about 20% and 190% with a concomitant tensile strength increase between about 15% to 30%. The elastic-plastic fracture toughness parameters and Charpy-V energy absorption both decrease and show only a slight sensitivity to dose. The irradiation-induced decrease in the elastic-plastic fracture toughness (J{sub def} at 1 mm crack extension) is between 20% to 65%; the range of J{sub 1C} values are 72.8 to 366 kJ/m{sup 2} for the irradiated materials. Similarly, Charpy V-notch results show a 40% to 60% decrease in impact energies.

  13. Study of Electrical Properties in SHI Irradiated 6H-SiC Crystals using Low Temperature Impedance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Viswanathan, E.; Murugaraj, R.; Selvakumar, S.; Kanjilal, D.; Sivaji, K.

    2011-07-01

    In the present work, low temperature impedance measurements were made on the pristine and Ag12+ ions irradiated 6H-SiC samples. The conductivity properties were studied at low temperature. The activation energies were calculated from the Arrhenius plot of d.c conductivity and impedance relaxation time. The activation energy was comparatively higher for the irradiated samples and found to be electronic conduction. From the study we observe the lower conductivity values exhibited for 300 K irradiated sample due to severe damage than the 80 K irradiated sample. The damage production mechanism and the change in electrical properties are discussed.

  14. Dose dependence of strength after low-temperature irradiation in metallic materials

    SciTech Connect

    Byun, Thak Sang; Li, Meimei; Farrell, Kenneth

    2013-01-01

    This study intends to review and characterize the low-temperature (< 200 oC) irradiation hardening behaviors in metallic materials and to propose new interpretations on the dose dependence of strength, particularly in the pre-hardening and saturation regimes. The analysis results of yield stress-dose curves indicate that four dose-dependence regimes exist: the pre-hardening, main hardening, saturation, and embrittlement regimes. The semi-log plots of yield stress versus dose data revealed that the pre-hardening regime displaying zero-hardening or softening was common at least for the alloys with low dose data available. It was observed that the dose range of the pre-hardening regime increased with the strength of material, which indicates that slower initiation in irradiation hardening is expected when strength is higher. For the majority of the metallic materials analyzed, it was reconfirmed that the exponent of the power-law hardening function was evaluated to be about 0.5 in the main hardening regime and about 0.1 in the saturation regime. In these positive hardening regimes the low strength pure metals such as Fe, Ta, Cu, and Zr displayed lower hardening exponents. The minimum dose to the saturation of irradiation hardening was in the range of 0.003 0.08 dpa, depending on the category of materials. It was also reaffirmed that there exists a strong relationship between the saturation in irradiation hardening and the occurrence of plastic instability at yield.

  15. Low-temperature neutron irradiation tests of superconducting magnet materials using reactor neutrons at KUR

    NASA Astrophysics Data System (ADS)

    Yoshida, M.; Nakamoto, T.; Ogitsu, T.; Xu, Q.; Itahashi, T.; Kuno, Y.; Kuriyama, Y.; Mori, Y.; Qin, B.; Sato, A.; Sato, K.; Yoshiie, T.

    2012-06-01

    Radiation resistant superconducting magnets are required for high intensity particle accelerators and associated secondary particle beamlines, such as the LHC upgrade and the COMET experiment at J-PARC. Expected neutron fluence on the superconducting coils reaches 1021 n/m2 or higher, therefore the magnet should be designed taking into account the irradiation effects. Irradiation tests for superconducting magnet materials have been carried out using reactor neutrons at Kyoto Univ. Research Reactor Institute. As a first step of the experiment, aluminum alloy stabilizer for superconducting cable was exposed to the reactor neutrons at low temperature and the resistance has been measured in situ during neutron exposure. After the irradiation at 12 K-15 K, the sample resistance increase was proportional to the integrated neutron fluence, and reached almost double for a fast-neutron fluence of 2.3×1020 n/m2 (>0.1 MeV). It is also confirmed that the induced resistance is fully recovered by thermal cycling to room temperature. Details of the irradiation test and the prospects are described.

  16. Dose Dependence of Strength After Low-Temperature Irradiation in Metallic Materials

    NASA Astrophysics Data System (ADS)

    Byun, Thak Sang; Li, Meimei; Farrell, Kenneth

    2013-01-01

    This study intends to review and characterize the low-temperature (<473 K [200 °C]) irradiation-hardening behaviors in metallic materials and to propose new interpretations on the dose dependence of strength, particularly in the prehardening and saturation regimes. The analysis of results of yield stress-dose curves indicate that four dose-dependence regimes exist: the prehardening, main hardening, saturation, and embrittlement regimes. The semilog plots of yield stress vs dose data revealed that the prehardening regime displaying zero hardening or softening was common at least for the alloys with low-dose data available. It was observed that the dose range of the prehardening regime increased with the strength of material, which indicates that slower initiation in irradiation hardening is expected when strength is higher. For the majority of the metallic materials analyzed, it was reconfirmed that the exponent of the power-law hardening function was evaluated to be about 0.5 in the main hardening regime and about 0.1 in the saturation regime. In these positive hardening regimes, the low strength pure metals such as Fe, Ta, Cu, and Zr displayed lower hardening exponents. The minimum dose to the saturation of irradiation hardening was in the range of 0.003 to 0.08 dpa, depending on the category of materials. It was also reaffirmed that there exists a strong relationship between the saturation in irradiation hardening and the occurrence of plastic instability at yield.

  17. Defect evolution in single crystalline tungsten following low temperature and low dose neutron irradiation

    DOE PAGES

    Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Katoh, Yutai; Wirth, Brian D; Snead, Lance Lewis

    2016-01-01

    The tungsten plasma-facing components of fusion reactors will experience an extreme environment including high temperature, intense particle fluxes of gas atoms, high-energy neutron irradiation, and significant cyclic stress loading. Irradiation-induced defect accumulation resulting in severe thermo-mechanical property degradation is expected. For this reason, and because of the lack of relevant fusion neutron sources, the fundamentals of tungsten radiation damage must be understood through coordinated mixed-spectrum fission reactor irradiation experiments and modeling. In this study, high-purity (110) single-crystal tungsten was examined by positron annihilation spectroscopy and transmission electron microscopy following low-temperature (~90 °C) and low-dose (0.006 and 0.03 dpa) mixed-spectrum neutronmore » irradiation and subsequent isochronal annealing at 400, 500, 650, 800, 1000, 1150, and 1300 °C. The results provide insights into microstructural and defect evolution, thus identifying the mechanisms of different annealing behavior. Following 1 h annealing, ex situ characterization of vacancy defects using positron lifetime spectroscopy and coincidence Doppler broadening was performed. The vacancy cluster size distributions indicated intense vacancy clustering at 400 °C with significant damage recovery around 1000 °C. Coincidence Doppler broadening measurements confirm the trend of the vacancy defect evolution, and the S–W plots indicate that only a single type of vacancy cluster is present. Furthermore, transmission electron microscopy observations at selected annealing conditions provide supplemental information on dislocation loop populations and visible void formation. This microstructural information is consistent with the measured irradiation-induced hardening at each annealing stage. This provides insight into tungsten hardening and embrittlement due to irradiation-induced matrix defects.« less

  18. Defect evolution in single crystalline tungsten following low temperature and low dose neutron irradiation

    SciTech Connect

    Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Katoh, Yutai; Wirth, Brian D; Snead, Lance Lewis

    2016-01-01

    The tungsten plasma-facing components of fusion reactors will experience an extreme environment including high temperature, intense particle fluxes of gas atoms, high-energy neutron irradiation, and significant cyclic stress loading. Irradiation-induced defect accumulation resulting in severe thermo-mechanical property degradation is expected. For this reason, and because of the lack of relevant fusion neutron sources, the fundamentals of tungsten radiation damage must be understood through coordinated mixed-spectrum fission reactor irradiation experiments and modeling. In this study, high-purity (110) single-crystal tungsten was examined by positron annihilation spectroscopy and transmission electron microscopy following low-temperature (~90 °C) and low-dose (0.006 and 0.03 dpa) mixed-spectrum neutron irradiation and subsequent isochronal annealing at 400, 500, 650, 800, 1000, 1150, and 1300 °C. The results provide insights into microstructural and defect evolution, thus identifying the mechanisms of different annealing behavior. Following 1 h annealing, ex situ characterization of vacancy defects using positron lifetime spectroscopy and coincidence Doppler broadening was performed. The vacancy cluster size distributions indicated intense vacancy clustering at 400 °C with significant damage recovery around 1000 °C. Coincidence Doppler broadening measurements confirm the trend of the vacancy defect evolution, and the S–W plots indicate that only a single type of vacancy cluster is present. Furthermore, transmission electron microscopy observations at selected annealing conditions provide supplemental information on dislocation loop populations and visible void formation. This microstructural information is consistent with the measured irradiation-induced hardening at each annealing stage. This provides insight into tungsten hardening and embrittlement due to irradiation-induced matrix defects.

  19. Defect evolution in single crystalline tungsten following low temperature and low dose neutron irradiation

    NASA Astrophysics Data System (ADS)

    Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Katoh, Yutai; Snead, Lance L.; Wirth, Brian D.

    2016-03-01

    The tungsten plasma-facing components of fusion reactors will experience an extreme environment including high temperature, intense particle fluxes of gas atoms, high-energy neutron irradiation, and significant cyclic stress loading. Irradiation-induced defect accumulation resulting in severe thermo-mechanical property degradation is expected. For this reason, and because of the lack of relevant fusion neutron sources, the fundamentals of tungsten radiation damage must be understood through coordinated mixed-spectrum fission reactor irradiation experiments and modeling. In this study, high-purity (110) single-crystal tungsten was examined by positron annihilation spectroscopy and transmission electron microscopy following low-temperature (∼90 °C) and low-dose (0.006 and 0.03 dpa) mixed-spectrum neutron irradiation and subsequent isochronal annealing at 400, 500, 650, 800, 1000, 1150, and 1300 °C. The results provide insights into microstructural and defect evolution, thus identifying the mechanisms of different annealing behavior. Following 1 h annealing, ex situ characterization of vacancy defects using positron lifetime spectroscopy and coincidence Doppler broadening was performed. The vacancy cluster size distributions indicated intense vacancy clustering at 400 °C with significant damage recovery around 1000 °C. Coincidence Doppler broadening measurements confirm the trend of the vacancy defect evolution, and the S-W plots indicate that only a single type of vacancy cluster is present. Furthermore, transmission electron microscopy observations at selected annealing conditions provide supplemental information on dislocation loop populations and visible void formation. This microstructural information is consistent with the measured irradiation-induced hardening at each annealing stage, providing insight into tungsten hardening and embrittlement due to irradiation-induced matrix defects.

  20. Proton Irradiation Creep in Pyrocarbon

    SciTech Connect

    Was, Gary S.; Campbell, Anne

    2011-10-01

    This project aims to understand irradiation creep in pyrocarbon using proton irradiation under controlled stresses and temperatures. Experiments will be conducted over a range of temperatures and stresses per the proposal submitted. The work scope will include the preparation of samples, measurement of deposition thickness, thickness uniformity, and anisotropy. The samples produced will be made in strips, which will be used for the creep experiments. Materials used will include pyrolytic carbon (PyC), Highly Oriented Pyrolytic Graphite (HOPG), or graphite strip samples in that order depending upon success. Temperatures tested under will range from 800°C to 1200°C, and stresses from 6MPa to 20.7MPa. Optional testing may occur at 900°C and 1100°C and stresses from 6MPa to 20.7MPa if funding is available.

  1. Tensile and impact properties of vanadium-base alloys irradiated at low temperatures in the ATR-A1 experiment

    SciTech Connect

    Tsai, H.; Nowicki, L.J.; Billone, M.C.; Chung, H.M.; Smith, D.L.

    1998-03-01

    Subsize tensile and Charpy specimens made from several V-(4-5)Cr-(4-5)Ti alloys were irradiated in the ATR-A1 experiment to study the effects of low-temperature irradiation on mechanical properties. These specimens were contained in lithium-bonded subcapsules and irradiated at temperatures between {approx}200 and 300 C. Peak neutron damage was {approx}4.7 dpa. Postirradiation testing of these specimens has begun. Preliminary results from a limited number of specimens indicate a significant loss of work-hardening capability and dynamic toughness due to the irradiation. These results are consistent with data from previous low-temperature neutron irradiation experiments on these alloys.

  2. Gamma-ray irradiation on microsized Nd-Fe-B and Sr-ferrite magnets at low temperature.

    PubMed

    Han, Young Chul; Cha, Hyun Gil; Kim, Chang Woo; Kim, Young Hwan; Ji, Eun Sun; Kang, Young Soo

    2009-07-01

    The gamma-ray irradiation on microsized Nd-Fe-B and Sr-Fe permanent magnet at low temperature and room temperature was investigated. The change of shape and magnetic properties of two kinds of magnet powder before and after irradiation at low temperature was measured. The crystal structure of each permanent magnet powders was analyzed using X-ray powder diffraction (XRD) and the size and shape were characterized by scanning electron microscope (SEM). The changed magnetic properties of magnet such as saturation magnetization (M(s)) and coercivity (H(c)) were measured by VSM.

  3. The proposed spallation neutron source and modernized reactor as possible sites for a low temperature irradiation facility in Germany*1

    NASA Astrophysics Data System (ADS)

    Böning, K.; Gläser, W.; Golub, R.; Meier, J.

    1982-07-01

    A feasibility study for a Spallation Neutron Source (SNQ) in Germany was completed in June 1981. In this project an intensity-modulated LINAC (100 pps) would provide a proton beam of energy 1100 MeV and time-average current Īp = 5 mA . Spallation neutrons are produced in the lead material of a rotating target wheel and moderated in a hybrid arrangement consisting of both a small H 2O volume and a large D 2O tank. Here the maximum values of the peak and time-average thermal fluxes are ̂gf th ≈ 1.3 × 10 16 cm -2 s -1 and ¯gf th ≈ 6.5 × 10 14 cm -2 s -1, respectively. A low temperature irradiation facility (LTIF) has been proposed to allow irradiations in the temperature range of 4.5 to 450 K with either thermal neutrons ( ¯gf th ≈ 1 × 10 14 cm -2 s -1) or fast neutrons ( ¯gf f ≈ 2 × 10 13 cm -2 s -1). The advantages and disadvantages of having this LTIF at the SNQ are discussed with respect to the alternative of installing it at a fission reactor. Finally, the example of a possible modernization and upgrading of the Munich research reactor FRM is used to discuss the performance of such a reactor and the concept of a LTIF in this case, and to point out the complementarity of an optimized SNQ (high- ̂gf applications) and such a modernized reactor (high- ¯gf applications).

  4. Response of Bacillus subtilis spores to dehydration and UV irradiation at extremely low temperatures.

    PubMed

    Dose, K; Klein, A

    1996-02-01

    Spores of Bacillus subtilis have been exposed to the conditions of extreme dehydration (argon/silica gel; simulated space vacuum) for up to 12 weeks at 298 K and 80 K in the dark. The inactivation has been correlated with the production of DNA-double strand-breaks. The temperature-dependence of the rate constants for inactivation or production of DNA-double strand-breaks is surprisingly low. Controls kept in the frozen state at 250 K for the same period of time showed no sign of deterioration. In another series of experiments the spores have been UV irradiated (253.7 nm) at 298 K, 200 K and 80 K after exposure to dehydrating conditions for 3 days. Fluence-effect relationships for inactivation, production of DNA-double strand-breaks and DNA-protein cross-links are presented. The corresponding F37-values for inactivation and production of DNA lesions are significantly increased only at 80 K (factor of 4 to 5). The data indicate that the low temperatures that prevail in the outer parts of the Solar System or at the nightside of Mars or the Moon are not sufficiently low to crucially inhibit inactivation by dehydration. Our data place further constraints on the panspermia hypothesis.

  5. Radiosterilisation of indomethacin PLGA/PEG-derivative microspheres: protective effects of low temperature during gamma-irradiation.

    PubMed

    Fernández-Carballido, Ana; Puebla, Patricia; Herrero-Vanrell, Rocío; Pastoriza, Pilar

    2006-04-26

    Currently, gamma-irradiation seems to be a good method for sterilising drug delivery systems made from biodegradable polymers. The gamma-irradiation of microspheres can cause several physicochemical changes in the polymeric matrix. These modifications are affected by the temperature, irradiation dose and nature of the encapsulated drug and additives. This study has aimed to evaluate the influence of temperature during the sterilisation process by gamma irradiation in indomethacin PLGA microspheres including a PEG-derivative. Microspheres were prepared by the solvent evaporation method from o/w emulsion and were then exposed to gamma-irradiation. A dose of 25 kGy was used to ensure effective sterilisation. Some microspheres were sterilised with dry ice protection that guaranteed a low temperature during the process whilst others were sterilised without such dry ice protection. The effects of gamma-irradiation on the characteristics of non-loaded PLGA/PEG-derivative and indomethacin loaded PLGA/PEG-derivative microspheres with and without protection were studied. Non-protected microspheres showed changes in their morphological surface, polymer glass transition temperature, molecular weight and release rate of indomethacin after sterilisation. However, microspheres sterilised with protection did not show significant differences after gamma-irradiation exposure. The sterilisation method was satisfactory when the indomethacin loaded microspheres including a PEG-derivative were exposed to gamma-irradiation at low temperature.

  6. Proton irradiation study of GFR candidate ceramics

    NASA Astrophysics Data System (ADS)

    Gan, Jian; Yang, Yong; Dickson, Clayton; Allen, Todd

    2009-06-01

    This work investigated the microstructural response of SiC, ZrC and ZrN irradiated with 2.6 MeV protons at 800 °C to a fluence of 2.75 × 10 19 protons/cm 2, corresponding to 0.71-1.8 displacement per atom (dpa), depending on the material. The change of lattice constant evaluated using HOLZ patterns is not observed. In comparison to Kr ion irradiation at 800 °C to 10 dpa from the previous studies, the proton irradiated ZrC and ZrN at 1.8 dpa show less irradiation damage to the lattice structure. The proton irradiated ZrC exhibits faulted loops which are not observed in the Kr ion irradiated sample. ZrN shows the least microstructural change from proton irradiation. The microstructure of 6H-SiC irradiated to 0.71 dpa consists of black dot defects at high density.

  7. Tonoplast lipid composition and proton pump of pineapple fruit during low-temperature storage and blackheart development.

    PubMed

    Zhou, Yuchan; Pan, Xiaoping; Qu, Hongxia; Underhill, Steven J R

    2014-05-01

    Vacuole represents a major storage organelle playing vital roles in pH homoeostasis and cellular detoxification. The chemical and functional properties of tonoplast in response to chilling temperature and their roles in chilling injury are largely unknown. In the current study, lipid composition of tonoplast and the activities of two vacuolar proton pumps, H?-ATPase (V-ATPase) and H?-pyrophosphatase (V-PPase), were investigated in accordance with the development of blackheart, a form of chilling injury in pineapple fruit (Ananas comosus). Chilling temperature at 10 °C for 1 week induced irreversible blackheart injury in concurrence with a substantial decrease in V-ATPase activity. By contrast, the activity was increased after 1 week at 25 °C. The activity of V-PPase was not changed under both temperatures. Level of total phospholipids of tonoplast decreased at 10 °C, but increased at 25 °C. There was no change at the level of total glycolipids under both temperatures. Thus, low temperature increased the ratio of total glycolipids vs. total phospholipids of tonoplast. Phosphatidylcholine and phosphatidylethanolamine were the predominant phospholipids of tonoplast. Low temperature increased the relative level of phosphatidic acid but decreased the percentage of both phosphatidylcholine and phosphatidylethanolamine. Unsaturated fatty acids accounted for over 60 % of the total tonoplast fatty acids, with C18:1 and C18:2 being predominant. Low temperature significantly decreased the percentage of C18:3. Modification of membrane lipid composition and its effect on the functional property of tonoplast at low temperature were discussed in correlation with their roles in the development of chilling injury in pineapple fruit.

  8. Proton irradiation of simple gas mixtures: Influence of irradiation parameters

    NASA Technical Reports Server (NTRS)

    Sack, Norbert J.; Schuster, R.; Hofmann, A.

    1990-01-01

    In order to get information about the influence of irradiation parameters on radiolysis processes of astrophysical interest, methane gas targets were irradiated with 6.5 MeV protons at a pressure of 1 bar and room temperature. Yields of higher hydrocarbons like ethane or propane were found by analysis of irradiated gas samples using gas chromatography. The handling of the proton beam was of great experimental importance for determining the irradiation parameters. In a series of experiments current density of the proton beam and total absorbed energy were shown to have a large influence on the yields of produced hydrocarbons. Mechanistic interpretations of the results are given and conclusions are drawn with regard to the chemistry and the simulation of various astrophysical systems.

  9. [A role of some intracellular signaling cascades in planarian regeneration activated under irradiation with low-temperature argon plasma].

    PubMed

    Ermakov, A M; Ermakova, O N; Maevskiĭ, E I

    2014-01-01

    Using inhibitory analysis the role of some intracellular signaling pathways in activation of planarian regeneration under the influence of low-temperature argon plasma (LTAP) has been investigated. Inactivation of specific inhibitors of intracellular signaling enzymes such as the receptor tyrosine kinase (EGFR), TGF β receptor, calmodulin, adenylate cyclase, phospholipase A2, phospholipase C, cyclin-dependent protein kinase, JAK2-protein kinase, JNK-protein kinase MEK-protein kinase led to inhibition of the head growth during its regeneration in planarians. Pretreatment with LTAP irradiation provided no inhibitory action of some cascades regulating proliferation. However, the inhibitors of the key regulators of regeneration: TGF β receptor, calmodulin and MEK-protein kinase completely suppressed the activating effect of plasma. Thus, by the example of regenerating planarians it is shown, that biological activity of low-temperature argon plasma LTAP is caused by modulation of a plurality of cellular signaling systems.

  10. Microstructure of V-4Cr-4Ti following low temperature neutron irradiation

    SciTech Connect

    Rice, P.M.; Snead, L.L.; Alexander, D.J.; Zinkle, S.J.

    1996-12-31

    The V-4Cr-4Ti alloys displays excellent mechanical properties, including a ductile-to-brittle transition temperature (DBTT) below - 200 C in the unirradiated conditions. Samples were fission neutron- irradiated in HFBR to a 0.4 dpa dose at 100-275 C. Mechanical tests showed significant irradiation hardening which increased with irradiation temperature. Charpy impact testing also showed a dramatic increase in DBTT on the order of 100 to 350 C. The mechanical property changes are correlated with preliminary results from TEM analysis of the defect microstructure resulting from the low-dose neutron irradiations. TEM of the irradiated material showed a nearly constant defect density of {approximately}1.6x10{sup 23}m{sup -3}, with an average defect diameter of slightly greater than 3 nm.

  11. Microstructural analysis of ferritic-martensitic steels irradiated at low temperature in HFIR

    SciTech Connect

    Hashimoto, N.; Robertson, J.P.; Rowcliffe, A.F.; Wakai, E.

    1998-09-01

    Disk specimens of ferritic-martensitic steel, HT9 and F82H, irradiated to damage levels of {approximately}3 dpa at irradiation temperatures of either {approximately}90 C or {approximately}250 C have been investigated by using transmission electron microscopy. Before irradiation, tempered HT9 contained only M{sub 23}C{sub 6} carbide. Irradiation at 90 C and 250 C induced a dislocation loop density of 1 {times} 10{sup 22} m{sup {minus}3} and 8 {times} 10{sup 21} m{sup {minus}3}, respectively. in the HT9 irradiated at 250 C, a radiation-induced phase, tentatively identified as {alpha}{prime}, was observed with a number density of less than 1 {times} 10{sup 20} m{sup {minus}3}. On the other hand, the tempered F82H contained M{sub 23}C{sub 6} and a few MC carbides; irradiation at 250 C to 3 dpa caused minor changes in these precipitates and induced a dislocation loop density of 2 {times} 10{sup 22} m{sup {minus}3}. Difference in the radiation-induced phase and the loop microstructure may be related to differences in the post-yield deformation behavior of the two steels.

  12. Low-temperature formation of high-quality gate oxide by ultraviolet irradiation on spin-on-glass

    SciTech Connect

    Usuda, R.; Uchida, K.; Nozaki, S.

    2015-11-02

    Although a UV cure was found to effectively convert a perhydropolysilazane (PHPS) spin-on-glass film into a dense SiO{sub x} film at low temperature, the electrical characteristics were never reported in order to recommend the use of PHPS as a gate-oxide material that can be formed at low temperature. We have formed a high-quality gate oxide by UV irradiation on the PHPS film, and obtained an interface midgap trap density of 3.4 × 10{sup 11 }cm{sup −2} eV{sup −1} by the UV wet oxidation and UV post-metallization annealing (PMA), at a temperature as low as 160 °C. In contrast to the UV irradiation using short-wavelength UV light, which is well known to enhance oxidation by the production of the excited states of oxygen, the UV irradiation was carried out using longer-wavelength UV light from a metal halide lamp. The UV irradiation during the wet oxidation of the PHPS film generates electron-hole pairs. The electrons ionize the H{sub 2}O molecules and facilitate dissociation of the molecules into H and OH{sup −}. The OH{sup −} ions are highly reactive with Si and improve the stoichiometry of the oxide. The UV irradiation during the PMA excites the electrons from the accumulation layer, and the built-in electric field makes the electron injection into the oxide much easier. The electrons injected into the oxide recombine with the trapped holes, which have caused a large negative flat band voltage shift after the UV wet oxidation, and also ionize the H{sub 2}O molecules. The ionization results in the electron stimulated dissociation of H{sub 2}O molecules and the decreased interface trap density.

  13. Low-temperature formation of high-quality gate oxide by ultraviolet irradiation on spin-on-glass

    NASA Astrophysics Data System (ADS)

    Usuda, R.; Uchida, K.; Nozaki, S.

    2015-11-01

    Although a UV cure was found to effectively convert a perhydropolysilazane (PHPS) spin-on-glass film into a dense SiOx film at low temperature, the electrical characteristics were never reported in order to recommend the use of PHPS as a gate-oxide material that can be formed at low temperature. We have formed a high-quality gate oxide by UV irradiation on the PHPS film, and obtained an interface midgap trap density of 3.4 × 1011 cm-2 eV-1 by the UV wet oxidation and UV post-metallization annealing (PMA), at a temperature as low as 160 °C. In contrast to the UV irradiation using short-wavelength UV light, which is well known to enhance oxidation by the production of the excited states of oxygen, the UV irradiation was carried out using longer-wavelength UV light from a metal halide lamp. The UV irradiation during the wet oxidation of the PHPS film generates electron-hole pairs. The electrons ionize the H2O molecules and facilitate dissociation of the molecules into H and OH-. The OH- ions are highly reactive with Si and improve the stoichiometry of the oxide. The UV irradiation during the PMA excites the electrons from the accumulation layer, and the built-in electric field makes the electron injection into the oxide much easier. The electrons injected into the oxide recombine with the trapped holes, which have caused a large negative flat band voltage shift after the UV wet oxidation, and also ionize the H2O molecules. The ionization results in the electron stimulated dissociation of H2O molecules and the decreased interface trap density.

  14. Performance of Magnet Insulation Systems at Low Temperature and After Reactor Irradiation

    SciTech Connect

    Bittner-Rohrhofer, K.; Humer, K.; Fillunger, H.; Maix, R.K.; Weber, H.W.

    2004-06-28

    Advanced composite materials reinforced with boron-free glass fibers are candidate insulation materials for fusion magnets, in particular for ITER. Thus, these systems require an excellent performance and mechanical integrity after irradiation. The present innovative organic insulation system consists of R-glass fiber reinforced tapes impregnated with an advanced cyanate-ester/epoxy resin. This composite is suitable for vacuum-pressure impregnation. In order to assess the radiation resistance of the mechanical properties, the laminate was irradiated in the TRIGA reactor (Vienna) to the ITER design fluence level of 1x1022 m-2 (E>0.1 MeV). The blend was screened at 77 K using the static tensile and short-beam-shear test prior to and after irradiation. In addition, tension-tension fatigue measurements were done in order to investigate the material performance under pulsed operating conditions.

  15. Performance of Magnet Insulation Systems at Low Temperature and After Reactor Irradiation

    NASA Astrophysics Data System (ADS)

    Bittner-Rohrhofer, K.; Humer, K.; Fillunger, H.; Maix, R. K.; Weber, H. W.

    2004-06-01

    Advanced composite materials reinforced with boron-free glass fibers are candidate insulation materials for fusion magnets, in particular for ITER. Thus, these systems require an excellent performance and mechanical integrity after irradiation. The present innovative organic insulation system consists of R-glass fiber reinforced tapes impregnated with an advanced cyanate-ester/epoxy resin. This composite is suitable for vacuum-pressure impregnation. In order to assess the radiation resistance of the mechanical properties, the laminate was irradiated in the TRIGA reactor (Vienna) to the ITER design fluence level of 1×1022 m-2 (E>0.1 MeV). The blend was screened at 77 K using the static tensile and short-beam-shear test prior to and after irradiation. In addition, tension-tension fatigue measurements were done in order to investigate the material performance under pulsed operating conditions.

  16. Low-temperature properties of neutron irradiated CuGeO3 single crystals

    NASA Astrophysics Data System (ADS)

    Gladczuk, L.; Mosiniewicz-Szablewska, E.; Dabkowska, H.; Baran, M.; Pytel, B.; Szymczak, R.; Szymczak, H.

    2000-07-01

    The effect of neutron irradiation on the magnetic properties of CuGeO3 single crystal which shows the spin-Peierls transition below T sp=14 K was investigated by means of electron paramagnetic resonance (EPR) and susceptibility measurements. It was found that the irradiation led to a decrease of the spin-Peierls transition temperature and induced appreciable changes in the EPR signal intensity, resonance linewidth, g-factor and magnetic susceptibility of this material. These changes may be associated with a partial suppression of both the energy gap and the dimerization within the Cu chains.

  17. Tritium isotope separation by CO2-laser irradiation at low temperatures

    NASA Astrophysics Data System (ADS)

    Takeuchi, K.; Satooka, S.; Makide, Y.

    1984-02-01

    Tritium isotope separation by CO2-laser induced multiphoton dissociation of CTF3 is investigated. For the optimization of the performance of this working substance, trifluoromethane, the conditions to yield high-selectivity at high-operating pressure and low-critical fluence for complete dissociation are studied using our deconvolution procedure. The irradiation conditions are varied over the following ranges; wavenumber: 1052 1087 cm-1, gas temperature: 25°C to -78°C, CHF3 pressure: 5 205 Torr. The selectivities exceeding 104 are observed for 85 205 Torr CHF3 at -78°C by the irradiation at 1057 cm-1.

  18. Low-temperature irradiation behavior of uranium-molybdenum alloy dispersion fuel

    NASA Astrophysics Data System (ADS)

    Meyer, M. K.; Hofman, G. L.; Hayes, S. L.; Clark, C. R.; Wiencek, T. C.; Snelgrove, J. L.; Strain, R. V.; Kim, K.-H.

    2002-08-01

    Irradiation tests have been conducted to evaluate the performance of a series of high-density uranium-molybdenum (U-Mo) alloy, aluminum matrix dispersion fuels. Fuel plates incorporating alloys with molybdenum content in the range of 4-10 wt% were tested. Two irradiation test vehicles were used to irradiate low-enrichment fuels to approximately 40 and 70 at.% 235U burnup in the advanced test reactor at fuel temperatures of approximately 65 °C. The fuel particles used to fabricate dispersion specimens for most of the test were produced by generating filings from a cast rod. In general, fuels with molybdenum contents of 6 wt% or more showed stable in-reactor fission gas behavior, exhibiting a distribution of small, stable gas bubbles. Fuel particle swelling was moderate and decreased with increasing alloy content. Fuel particles with a molybdenum content of 4 wt% performed poorly, exhibiting extensive fuel-matrix interaction and the growth of relatively large fission gas bubbles. Fuel particles with 4 or 6 wt% molybdenum reacted more rapidly with the aluminum matrix than those with higher-alloy content. Fuel particles produced by an atomization process were also included in the test to determine the effect of fuel particle morphology and microstructure on fuel performance for the U-10Mo composition. Both of the U-10Mo fuel particle types exhibited good irradiation performance, but showed visible differences in fission gas bubble nucleation and growth behavior.

  19. Effect of Low Temperature Ion Irradiation on the Microstructure of Nitride Ceramics

    SciTech Connect

    Eatherly, W.S.; Hensley, D.K.; Jones, J.W.; Snead, L.L.; Zinkle, S.J.

    1998-11-30

    Cross-section transmission electron microscopy was used to investigate the microstructure of polycrystalline silicon nitride (Si{sub 3}N{sub 4}) and aluminum nitride (AlN) following 2 MeV Si ion irradiation at 80 and 400 K up to a fluence of 4 x 10{sup 20} ions/m{sup 2} (maximum damage of {approximately}10 displacements per atom, dpa). A buried amorphous band was observed at both temperatures in Si{sub 3}N{sub 4} in the region corresponding to the peaks in the implanted ion and displacement damage. From a comparison of Si{sub 3}N{sub 4} specimens irradiated at different fluences, it is concluded that the amorphization is primarily controlled by the implanted Si concentration rather than the displacement damage level. Si{sub 3}N{sub 4} amorphization did not occur in regions well-separated from the implanted ions for doses up to at least 3 dpa at 80 K, whereas amorphization occurred in the ion implanted region (calculated Si concentration >0.01 at.%) for damage levels as low as {approximately}0.6 dpa. The volumetric swelling associated with the amorphization of Si{sub 3}N{sub 4} is < 10%. Amorphization was not observed in any of the irradiated AIN specimens. A moderate density of small ({approximately}3 nm) defect clusters were observed in the crystalline damaged regions of both the Si{sub 3}N{sub 4} and AIN specimens at both irradiation temperatures. Aligned network dislocations were also observed in the AIN specimen irradiated to high dose at 80 K.

  20. Hardness of Carburized Surfaces in 316LN Stainless Steel after Low Temperature Neutron Irradiation

    SciTech Connect

    Byun, TS

    2005-01-31

    A proprietary surface carburization treatment is being considered to minimize possible cavitation pitting of the inner surfaces of the stainless steel target vessel of the SNS. The treatment gives a large supersaturation of carbon in the surface layers and causes substantial hardening of the surface. To answer the question of whether such a hardened layer will remain hard and stable during neutron irradiation, specimens of the candidate materials were irradiated in the High Flux Isotope Reactor (HFIR) to an atomic displacement level of 1 dpa. Considerable radiation hardening occurred in annealed 316LN stainless steel and 20% cold rolled 316LN stainless steel, and lesser radiation hardening in Kolsterised layers on these materials. These observations coupled with optical microscopy examinations indicate that the carbon-supersaturated layers did not suffer radiation-induced decomposition and softening.

  1. Purification of Carbon Nanotubes by Proton Irradiation

    NASA Astrophysics Data System (ADS)

    Kim, Euikwoun; Lee, Jeonggil; Lee, Younman; Jeon, Jaekyun; Kim, Jae-Yong; Kim, Jeongha; Shin, Kwanwoo; Youn, Sang-Pil; Kim, Kyeryung

    2007-10-01

    Carbon nanotubes (CNTs) exhibit variety of superior physical properties including well-defined nanodimensional structure, high electrical and thermal conductivity, and good mechanical stability against external irradiations. Further, a large specific surface area per unit weight suggests that carbon nanotubes could be excellent candidates for gas storage, purification, and separation. However, the practical application of CNTs is limited mainly due to the metallic impurities that were used as a catalyst during the fabrication process. Here, we irradiated CNTs by using high energy proton beams (35.7 MeV at the Bragg Peak). Interestingly, metallic impurities such as Fe, Ni, Co and chunk of amorphous carbon that were attached on the surface of CNTs were completely removed after the irradiation. The mechanism of such the purification process is not understood. The possible speculation will be demonstrated combined with the changes of physical properties including the appearance of the magnetism after the irradiation.

  2. Low Temperature Mechanical Properties of Cyanate Ester Insulation Systems After Irradiation

    NASA Astrophysics Data System (ADS)

    Fabian, P. E.; Munshi, N. A.; Feucht, S. W.; Bittner-Rohrhofer, K.; Humer, K.; Weber, H. W.

    2004-06-01

    Recent development of alternative resin chemistries has resulted in new, fiber-reinforced, insulation systems for use in superconducting and fusion magnet applications. When compared to traditional epoxy resins, these insulation systems, based on cyanate ester resin chemistry, offer increased radiation resistance and higher operating temperatures that are demanded by new fusion reactor designs, such as the Fusion Ignition Research Experiment (FIRE). The design parameters for FIRE Toroidal Field (TF) coils call for an insulation system capable of withstanding a combined gamma and neutron radiation dose greater than 108 Gy (1010 Rad) and operate at temperatures ranging from cryogenic (77 K) to elevated temperatures up to 373 K. Several of these newly developed composite insulation systems, suitable for the vacuum impregnation, pre-preg, and high-pressure laminate fabrication processes, were irradiated in the TRIGA reactor (Vienna) to varying levels of radiation to gauge their radiation resistance. The insulation materials' shear and compression properties measured at cryogenic temperatures before and after irradiation are presented.

  3. Low Temperature Fatigue Properties of Advanced Cyanate-Ester Blends after Reactor Irradiation

    NASA Astrophysics Data System (ADS)

    Bittner-Rohrhofer, K.; Humer, K.; Weber, H. W.; Fabian, P. E.; Munshi, N. A.; Feucht, S. W.

    2004-06-01

    Fiber reinforced composites offer a broad spectrum of applications due to their excellent material performance under demanding conditions. Therefore, these materials will also be employed as insulation systems for the superconducting magnets in fusion devices. However, high doses of gamma and neutron irradiation lead to a drastic damage mostly of the organic matrices, such as pure epoxy resins. An improvement of these composites with regard to higher radiation resistance is of special importance to ensure stable coil operation over the plant lifetime. Recently, a series of advanced S2-glass fiber composites was developed, which consist of novel cyanate ester (CE) blends. All systems were irradiated in the TRIGA reactor (Vienna, Austria) to a neutron fluence of 1×1021 and 1×1022 m-2 (E>0.1 MeV), in order to assess the radiation hardness of their ultimate tensile strength. Furthermore, the material performance under cyclic load was investigated by tension-tension fatigue measurements at 77 K in view of the pulsed ITER operating conditions.

  4. Low Temperature Fatigue Properties of Advanced Cyanate-Ester Blends after Reactor Irradiation

    SciTech Connect

    Bittner-Rohrhofer, K.; Humer, K.; Weber, H.W.; Fabian, P.E.; Munshi, N.A.; Feucht, S.W.

    2004-06-28

    Fiber reinforced composites offer a broad spectrum of applications due to their excellent material performance under demanding conditions. Therefore, these materials will also be employed as insulation systems for the superconducting magnets in fusion devices. However, high doses of gamma and neutron irradiation lead to a drastic damage mostly of the organic matrices, such as pure epoxy resins. An improvement of these composites with regard to higher radiation resistance is of special importance to ensure stable coil operation over the plant lifetime. Recently, a series of advanced S2-glass fiber composites was developed, which consist of novel cyanate ester (CE) blends. All systems were irradiated in the TRIGA reactor (Vienna, Austria) to a neutron fluence of 1x1021 and 1x1022 m-2 (E>0.1 MeV), in order to assess the radiation hardness of their ultimate tensile strength. Furthermore, the material performance under cyclic load was investigated by tension-tension fatigue measurements at 77 K in view of the pulsed ITER operating conditions.

  5. Effects of low temperature neutron irradiation on deformation behavior of austenitic stainless steels

    SciTech Connect

    Pawel, J.E.; Rowcliffe, A.F.; Alexander, D.J.; Grossbeck, M.L.; Shiba, K.

    1996-04-01

    An austenitic stainless steel, designated 316LN-IG, has been chosen for the first wall/shield (FW/S) structure for the International Thermonuclear Experimental Reactor (ITER). The proposed operational temperature range for the structure (100 to 250{degree}C) is below the temperature regimes for void swelling (400-600{degree}C) and for helium embrittlement (500-700{degree}C). However, the proposed neutron dose is such that large changes in yield strength, deformation mode, and strain hardening capacity could be encountered which could significantly affect fracture properties. Definition of the irradiation regimes in which this phenomenon occurs is essential to the establishment of design rules to protect against various modes of failure.

  6. Microstructure of V-4Cr-4Ti alloy after low-temperature irradiation by ions and neutrons

    SciTech Connect

    Gazda, J.; Meshii, M.; Chung, H.M.

    1998-03-01

    Mechanical properties of V-4Cr-4Ti alloy were investigated after low-temperature (<420 C) irradiation. The effects of fast neutrons at 390 C were investigated by irradiation to {approx}4 dpa in the X530 experiment in the EBR-II reactor; these tests were complemented by irradiation with single (4.5-MeV Ni{sup ++}) and dual ion beams (350-keV He{sup +} simultaneously with 4.5-MeV Ni{sup ++}). TEM observations showed the formation of a high density of point-defect clusters and dislocation loops (<30 nm diameter) distributed uniformly in the specimens. Mechanical-property testing showed embrittlement of the alloy. TEM investigations of deformed microstructures were used to determine the causes of embrittlement and yielded observation of dislocation channels propagating through the undeformed matrix. Channels are the sole slip paths and cause early onset of necking and loss of work-hardening in this alloy. Based on a review of the available literature, suggestions are made for further research of slip localization in V-base alloys.

  7. Single proton counting at the RIKEN cell irradiation facility

    SciTech Connect

    Mäckel, V. Puttaraksa, N.; Kobayashi, T.; Yamazaki, Y.

    2015-08-15

    We present newly developed tapered capillaries with a scintillator window, which enable us to count single protons at the RIKEN cell irradiation setup. Their potential for performing single proton irradiation experiments at our beamline setup is demonstrated with CR39 samples, showing a single proton detection fidelity of 98%.

  8. Quantum mechanical study of the proton exchange in the ortho-para H2 conversion reaction at low temperature.

    PubMed

    Honvault, P; Jorfi, M; González-Lezana, T; Faure, A; Pagani, L

    2011-11-14

    Ortho-para H(2) conversion reactions mediated by the exchange of a H(+) proton have been investigated at very low energy for the first time by means of a time independent quantum mechanical (TIQM) approach. State-to-state probabilities and cross sections for H(+) + H(2) (v = 0, j = 0,1) processes have been calculated for a collision energy, E(c), ranging between 10(-6) eV and 0.1 eV. Differential cross sections (DCSs) for H(+) + H(2) (v = 0, j = 1) → H(+) + H(2) (v' = 0, j' = 0) for very low energies only start to develop a proper global minimum around the sideways scattering direction (θ≈ 90°) at E(c) = 10(-3) eV. Rate coefficients, a crucial information required for astrophysical models, are provided between 10 K and 100 K. The relaxation ortho-para process j = 1 → j' = 0 is found to be more efficient than the j = 0 → j' = 1 conversion at low temperatures, in line with the extremely small ratio between the ortho and para species of molecular hydrogen predicted at the temperature of interstellar cold molecular clouds. The results obtained by means of a statistical quantum mechanical (SQM) model, which has previously proved to provide an adequate description of the dynamics of the title reactions at a higher collision energy regime, have been compared with the TIQM results. A reasonable good agreement has been found with the only exception of the DCSs for the H(+) + H(2) (v = 0, j = 1) → H(+) + H(2) (v' = 0, j' = 0) process at very low energy. SQM cross sections are also slightly below the quantum results. Estimates for the rate coefficients, in good accord with the TIQM values, are a clear improvement with respect to pioneering statistical studies on the reaction.

  9. Chemical ordering in ilmenite-hematite bulk ceramics through proton irradiation

    SciTech Connect

    Allen, D.M.; Navarrete, L.; Dou, J.; Schad, R.; Padmini, P.; Kale, P.; Pandey, R.K.; Shojah-Ardalan, S.; Wilkins, R.

    2004-12-13

    We demonstrated the capability of MeV proton irradiation to promote chemical ordering processes in a solid at low temperature. We used the ilmenite-hematite solid solution system which allows estimation of the degree of ordering through measurement of its magnetization. Normally, ordering through diffusion would require high temperature annealing. At high temperatures, however, the equilibrium state would be less ordered and thus the achievable ordering incomplete. High energetic protons continuously transfer energy to the sample through electronic interaction which locally deposits large quantities of energy without a general increase of the sample temperature. This promotes diffusion processes which allow the system to relax towards the ordered equilibrium state.

  10. Microstructural evolution of RPV steels under proton and ion irradiation studied by positron annihilation spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiang, J.; Wu, Y. C.; Liu, X. B.; Wang, R. S.; Nagai, Y.; Inoue, K.; Shimizu, Y.; Toyama, T.

    2015-03-01

    The microstructural evolution of reactor pressure vessel (RPV) steels induced by proton and heavy ion irradiation at low temperature (∼373 K) has been investigated using positron annihilation spectroscopy (PAS), atom probe tomography (APT), transmission electron microscopy (TEM) and nanoindentation. The PAS results indicated that both proton and heavy ion irradiation produce a large number of matrix defects, which contain small-size defects such as vacancies, vacancy-solute complexes, dislocation loops, and large-size vacancy clusters. In proton irradiated RPV steels, the size and number density of vacancy cluster defects increased rapidly with increasing dose due to the migration and agglomeration of vacancies. In contrast, for Fe ion irradiated steels, high density, larger size vacancy clusters can be easily induced at low dose, showing saturation in PAS response with increasing dose. No clear precipitates, solute-enriched clusters or other forms of solute segregation were observed by APT. Furthermore, dislocation loops were observed by TEM after 1.0 dpa, 240 keV proton irradiation, and an increase of the average nanoindentation hardness was found. It is suggested that ion irradiation produces many point defects and vacancy cluster defects, which induce the formation of dislocation loops and the increase of nanoindentation hardness.

  11. Fractionated proton beam irradiation of pituitary adenomas

    SciTech Connect

    Ronson, Brian B.; Schulte, Reinhard W.; Han, Khanh P.; Loredo, Lilia N.; Slater, James M.; Slater, Jerry D. . E-mail: jdslater@dominion.llumc.edu

    2006-02-01

    Purpose: Various radiation techniques and modalities have been used to treat pituitary adenomas. This report details our experience with proton treatment of these tumors. Methods and Materials: Forty-seven patients with pituitary adenomas treated with protons, who had at least 6 months of follow-up, were included in this analysis. Forty-two patients underwent a prior surgical resection; 5 were treated with primary radiation. Approximately half the tumors were functional. The median dose was 54 cobalt-gray equivalent. Results: Tumor stabilization occurred in all 41 patients available for follow-up imaging; 10 patients had no residual tumor, and 3 had greater than 50% reduction in tumor size. Seventeen patients with functional adenomas had normalized or decreased hormone levels; progression occurred in 3 patients. Six patients have died; 2 deaths were attributed to functional progression. Complications included temporal lobe necrosis in 1 patient, new significant visual deficits in 3 patients, and incident hypopituitarism in 11 patients. Conclusion: Fractionated conformal proton-beam irradiation achieved effective radiologic, endocrinological, and symptomatic control of pituitary adenomas. Significant morbidity was uncommon, with the exception of postradiation hypopituitarism, which we attribute in part to concomitant risk factors for hypopituitarism present in our patient population.

  12. Anomalous grain growth in the surface region of a nanocrystalline CeO2 film under low-temperature heavy ion irradiation

    SciTech Connect

    Edmondson, Philip D.; Zhang, Yanwen; Moll, Sandra J.; Varga, Tamas; Namavar, Fereydoon; Weber, William J.

    2012-06-15

    Grain growth and phase stability of nanocrystalline ceria are investigated under ion irradiation at different temperatures. Irradiations at temperatures of 300 and 400 K result in uniform grain growth throughout the film. Anomalous grain growth is observed in thin films of nanocrystalline ceria under 3 MeV Au+ irradiation at 160 K. At this low temperature, significant grain growth is observed within 100 nm from the surface, no obvious growth is detected in the rest of the films. While the grain growth is attributed to a defect-stimulated mechanism at room temperature and above, a defect diffusion-limited mechanism is significant at low temperature with the primary defect responsible being the oxygen vacancy. The nanocrystalline grains remain in the cubic phase regardless of defect kinetics.

  13. Anomalous grain growth in the surface region of a nanocrystalline CeO2 film under low-temperature heavy ion irradiation

    SciTech Connect

    Edmondson, Dr. Philip; Zhang, Yanwen; Moll, Sandra; Varga, Tamas; Namavar, Fereydoon; Weber, William J

    2012-01-01

    Grain growth and phase stability of nanocrystalline ceria are investigated under ion irradiation at different temperatures. Irradiations at temperatures of 300 and 400 K result in uniform grain growth throughout the film. Anomalous grain growth is observed in thin films of nanocrystalline ceria under 3 MeV Au+ irradiation at 160 K. At this low temperature, significant grain growth is observed within 100 nm from the surface, no obvious growth is detected in the rest of the films. While the grain growth is attributed to a defect-stimulated mechanism at room temperature and above, a defect diffusion-limited mechanism is significant at low temperature with the primary defect responsible being the oxygen vacancy.

  14. Planetary quarantine in the solar system. Survival rates of some terrestrial organisms under simulated space conditions by proton irradiation

    NASA Astrophysics Data System (ADS)

    Koike, J.; Oshima, T.

    We have been studying the survival rates of some species of terrestrial unicellular and multicellular organism (viruses, bacteria, yeasts, fungi, algae, etc.) under simulated interstellar conditions, in connection with planetary quarantine. The interstellar environment in the solar system has been simulated by low temperature, high vacuum (77 K, 4 × 10 -8 torr), and proton irradiation from a Van de Graaff generator. After exposure to a barrage of protons corresponding to about 250 years of irradiation in solar space, tobacco mosaic virus, Bacillus subtilis spores, Staphylococcus aureus, Micrococcus flavus, Aspergillus niger spores, and Clostridium mangenoti spores showed survival rates of 82, 45, 74, 13, 28, and 25%, respectively.

  15. [Radiobiological effects of total mice irradiation with Bragg's peak protons].

    PubMed

    Ivanov, A A; Molokanov, A G; Ushakov, I B; Bulynina, T M; Vorozhtsova, S V; Abrosimova, A N; Kryuchkova, D M; Gaevsky, V N

    2013-01-01

    Outbred CD-1 female mice were irradiated in a proton beam (171 MeV, 5 Gy) on the phasotron at the Joint Institute of Nuclear Research (Dubna, Russia). Radiation was delivered in two points of the depth dose distribution: at the beam entry and on Bragg's peak. Technical requirements for studying the effects of Bragg's peak protons on organism of experimental animals were specified. It was recognized that protons with high linear energy transfer (mean LET = 1.6 keV/microm) cause a more severe damaging effect to the hemopoietic system and cytogenetic apparatus in bone marrow cells as compared with entry protons and 60Co gamma-quanta. It was shown that recovery of the main hemopoietic organs and immunity as well as elimination of chromosomal aberrations take more time following irradiation with Bragg's peak protons but not protons with the energy of 171 MeV.

  16. Raman Microscopic Characterization of Proton-Irradiated Polycrystalline Diamond Films

    NASA Technical Reports Server (NTRS)

    Newton, R. L.; Davidson, J. L.; Lance, M. J.

    2004-01-01

    The microstructural effects of irradiating polycrystalline diamond films with proton dosages ranging from 10(exp 15) to 10(exp 17) H(+) per square centimeter was examined. Scanning Electron Microscopy and Raman microscopy were used to examine the changes in the diamond crystalline lattice as a function of depth. Results indicate that the diamond lattice is retained, even at maximum irradiation levels.

  17. Surface, structural and tensile properties of proton beam irradiated zirconium

    NASA Astrophysics Data System (ADS)

    Rafique, Mohsin; Chae, San; Kim, Yong-Soo

    2016-02-01

    This paper reports the surface, structural and tensile properties of proton beam irradiated pure zirconium (99.8%). The Zr samples were irradiated by 3.5 MeV protons using MC-50 cyclotron accelerator at different doses ranging from 1 × 1013 to 1 × 1016 protons/cm2. Both un-irradiated and irradiated samples were characterized using Field Emission Scanning Electron Microscope (FESEM), X-ray Diffraction (XRD) and Universal Testing Machine (UTM). The average surface roughness of the specimens was determined by using Nanotech WSxM 5.0 develop 7.0 software. The FESEM results revealed the formation of bubbles, cracks and black spots on the samples' surface at different doses whereas the XRD results indicated the presence of residual stresses in the irradiated specimens. Williamson-Hall analysis of the diffraction peaks was carried out to investigate changes in crystallite size and lattice strain in the irradiated specimens. The tensile properties such as the yield stress, ultimate tensile stress and percentage elongation exhibited a decreasing trend after irradiation in general, however, an inconsistent behavior was observed in their dependence on proton dose. The changes in tensile properties of Zr were associated with the production of radiation-induced defects including bubbles, cracks, precipitates and simultaneous recovery by the thermal energy generated with the increase of irradiation dose.

  18. Proton irradiation effects on beryllium - A macroscopic assessment

    NASA Astrophysics Data System (ADS)

    Simos, Nikolaos; Elbakhshwan, Mohamed; Zhong, Zhong; Camino, Fernando

    2016-10-01

    Beryllium, due to its excellent neutron multiplication and moderation properties, in conjunction with its good thermal properties, is under consideration for use as plasma facing material in fusion reactors and as a very effective neutron reflector in fission reactors. While it is characterized by unique combination of structural, chemical, atomic number, and neutron absorption cross section it suffers, however, from irradiation generated transmutation gases such as helium and tritium which exhibit low solubility leading to supersaturation of the Be matrix and tend to precipitate into bubbles that coalesce and induce swelling and embrittlement thus degrading the metal and limiting its lifetime. Utilization of beryllium as a pion production low-Z target in high power proton accelerators has been sought both for its low Z and good thermal properties in an effort to mitigate thermos-mechanical shock that is expected to be induced under the multi-MW power demand. To assess irradiation-induced changes in the thermal and mechanical properties of Beryllium, a study focusing on proton irradiation damage effects has been undertaken using 200 MeV protons from the Brookhaven National Laboratory Linac and followed by a multi-faceted post-irradiation analysis that included the thermal and volumetric stability of irradiated beryllium, the stress-strain behavior and its ductility loss as a function of proton fluence and the effects of proton irradiation on the microstructure using synchrotron X-ray diffraction. The mimicking of high temperature irradiation of Beryllium via high temperature annealing schemes has been conducted as part of the post-irradiation study. This paper focuses on the thermal stability and mechanical property changes of the proton irradiated beryllium and presents results of the macroscopic property changes of Beryllium deduced from thermal and mechanical tests.

  19. Charging and Discharging Characteristic on PI Films Irradiated by Protons

    NASA Astrophysics Data System (ADS)

    Uchiyama, Ryo; Miyake, Hiroaki; Tanaka, Yasuhiro; Takada, Tatuo

    We evaluate the dielectric characteristic of polymeric materials for MLI (Multi Layer Insulator, a kind of thermal insulation material) for spacecraft under high energy proton irradiation using results of space charge distribution. Spacecrafts have a serious damage due to the electro-static discharge accident. The electric charges are accumulated in the polymeric materials due to radioactive rays, especially electrons and protons. The charge accumulation is the origin of aging and discharging phenomena, furthermore those become trigger for spacecraft operation anomaly. Therefore, we need to obtain the space charge distribution in the bulks. In this study, we especially focused polyimide films for MLI irradiated by high energy proton. We measured the space charge distribution in the bulks during and after proton beam irradiation. From the results, it is found that positive charges accumulate in the bulk at the position of proton penetration depth. We also obtained same tendency from the results of conductivity measurement treated by ASTM method. From the above reason, we have studied the dielectric characteristics of MLI materials irradiated by radioactive rays, especially we focused the condition of proton irradiation. In this paper, we discuss the dielectric phenomena and the relationship between conductivity and charge accumulation in bulks.

  20. Measurement of thermal conductivity in proton irradiated silicon

    SciTech Connect

    Marat Khafizov; Clarissa Yablinsky; Todd Allen; David Hurley

    2014-04-01

    We investigate the influence of proton irradiation on thermal conductivity in single crystal silicon. We apply laser based modulated thermoreflectance technique to extract the change in conductivity of the thin layer damaged by proton irradiation. Unlike time domain thermoreflectance techniques that require application of a metal film, we perform our measurement on uncoated samples. This provides greater sensitivity to the change in conductivity of the thin damaged layer. Using sample temperature as a parameter provides a means to deduce the primary defect structures that limit thermal transport. We find that under high temperature irradiation the degradation of thermal conductivity is caused primarily by extended defects.

  1. Measurement of thermal conductivity in proton irradiated silicon

    NASA Astrophysics Data System (ADS)

    Khafizov, Marat; Yablinsky, Clarissa; Allen, Todd R.; Hurley, David H.

    2014-04-01

    We investigate the influence of proton irradiation on thermal conductivity in single crystal silicon. We apply a laser based modulated thermoreflectance technique to measure the change in conductivity of the thin layer damaged by proton irradiation. Unlike time domain thermoreflectance techniques that require application of a metal film, we perform our spatial domain measurement on uncoated samples. This provides greater sensitivity to the change in conductivity of the thin damaged layer. Using sample temperature as a parameter provides a means to deduce the primary defect structures that limit thermal transport. We find that under high temperature irradiation the degradation of thermal conductivity is caused primarily by extended defects.

  2. Accumulation and annealing of radiation defects under low-temperature electron and neutron irradiation of ODS steel and Fe-Cr alloys

    NASA Astrophysics Data System (ADS)

    Arbuzov, V. L.; Goshchitskii, B. N.; Sagaradze, V. V.; Danilov, S. E.; Kar'kin, A. E.

    2010-10-01

    The processes of accumulation and annealing of radiation defects at low-temperature (77 K) electron and neutron irradiation and their effect on the physicomechanical properties of Fe-Cr alloys and oxide dispersion strengthened (ODS) steel have been studied. It has been shown that the behavior of radiation defects in ODS steel and Fe-Cr alloys is qualitatively similar. Above 250 K, radiation-induced processes of the solid solution decomposition become conspicuous. These processes are much less pronounced in ODS steel because of specific features of its microstructure. Processes related to the overlapping of displacement cascades under neutron irradiation have been considered. It has been shown that, in this case, it is the increase in the size of vacancy clusters, rather than the growth of their concentration, that is prevailing. Possible mechanisms of the radiation hardening of the ODS steel and the Fe-13Cr alloy upon irradiation and subsequent annealing have been discussed.

  3. Layered protonated titanate nanosheets synthesized with a simple one-step, low-temperature, urea-modulated method as an effective pollutant adsorbent.

    PubMed

    Lin, Cheng-Hsien; Wong, David Shan-Hill; Lu, Shih-Yuan

    2014-10-01

    A simple one-step, low-temperature, urea-modulated method is developed for the synthesis of layered protonated titanate nanosheets (LPTNs). Urea serves as an indirect ammonium ion source, and the controlled supply of the ammonium ion slows the crystalline formation process and enables the production of the LPTNs from amorphous intermediate through aging-induced restructuring. The resulting LPTNs exhibit excellent adsorption capacities for methylene blue and Pb(2+) because of their high specific surface areas and excellent ion-exchange capability. Intercalation of Pb(2+) into the interlayer space of the LPTNs is evidenced by the relevant X-ray diffraction patterns on perturbation of the layered structure. The LPTNs prove to be a promising adsorbent in wastewater treatment for adsorption removal of metal ions or cationic organic dyes. PMID:25198517

  4. THE INFLUENCE OF NEUTRON-IRRADIATION AT LOW TEMPERATURES ON THE DIELECTRIC PARAMETERS OF 3C-SiC

    SciTech Connect

    J.A.A. Engelbrecht; G. Deyzel; E. Minnaar; W.E. Goosen; I. J. van Rooyen

    2014-04-01

    3C-SiC wafers were irradiated with neutrons of various fluences and at low (200 - 400 ?C) irradiation temperatures. Fourier Transform infrared (FTIR) reflectance spectra were obtained for the samples, and the spectra used to extract the dielectric parameters for each specimen, using statistical curve-fitting procedures. Analysis of all data revealed trends in reflectance peak heights as well as in the dielectric parameters. The surface roughness of the irradiated samples was measured by atomic force spectroscopy (AFM) and certain trends could be ascribed to surface roughness.

  5. Proton irradiation of germanium isotope multilayer structures at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Schneider, S.; Bracht, H.; Petersen, M. C.; Hansen, J. Lundsgaard; Larsen, A. Nylandsted

    2008-02-01

    Irradiation of germanium (Ge) isotope heterostructures with 2.5 MeV protons have been performed at 550 °C. The applied proton flux was varied between 1.0 and 1.5 μA leading to various rates of Frenkel pair production. After irradiation, concentration profiles of the Ge isotopes were recorded by means of secondary ion mass spectrometry (SIMS). An inhomogeneous broadening of the isotope structure was observed. In addition to the effect of irradiation enhanced self-diffusion, an influence of the formation of microscopic defects on the detected broadening was ascertained. Atomic force and scanning electron microscopy show that the microscopic defects are most probably resulting from an aggregation of vacancies formed during irradiation. Numerical analysis of Ge profiles not disturbed by microdefect formation indicates a significant contribution of self-interstitials to self-diffusion under irradiation.

  6. Long-term results of proton beam irradiated uveal melanomas

    SciTech Connect

    Gragoudas, E.S.; Seddon, J.M.; Egan, K.; Glynn, R.; Munzenrider, J.; Austin-Seymour, M.; Goitein, M.; Verhey, L.; Urie, M.; Koehler, A.

    1987-04-01

    The first 128 consecutive patients with uveal melanomas treated with proton beam irradiation were studied in order to evaluate survival and visual acuity status of patients with relatively long-term follow-up. The median follow-up was 5.4 years, and no patient was lost to follow-up. All tumors showed regression. The most recent visual acuity was 20/40 or better in 35% and 20/100 or better in 58%. Eight eyes were enucleated because of complications. Metastasis developed in 26 patients (20.5%) from 3 months to 7 years after treatment. Results indicate that proton irradiation is quite successful for achieving local control of uveal melanomas. A large proportion of the treated eyes maintained useful vision. Five-year follow-up data indicate that proton irradiation has no deleterious effect on the likelihood of the development of metastasis.

  7. Effect of high energy proton irradiation on InAs/GaAs quantum dots: Enhancement of photoluminescence efficiency (up to {approx}7 times) with minimum spectral signature shift

    SciTech Connect

    Sreekumar, R.; Mandal, A.; Gupta, S.K.; Chakrabarti, S.

    2011-11-15

    Graphical abstract: Authors demonstrate enhancement in photoluminescence efficiency (7 times) in single layer InAs/GaAs quantum dots using proton irradiation without any post-annealing treatment via either varying proton energy (a) or fluence (b). The increase in PL efficiency is explained by a proposed model before (c) and after irradiation (d). Highlights: {yields} Proton irradiation improved PL efficiency in InAs/GaAs quantum dots (QDs). {yields} Proton irradiation favoured defect and strain annihilation in InAs/GaAs QDs. {yields} Reduction in defects/non-radiative recombination improved PL efficiency. {yields} Protons could be used to improve PL efficiency without spectral shift. {yields} QD based devices will be benefited by this technique to improve device performance. -- Abstract: We demonstrate 7-fold increase of photoluminescence efficiency in GaAs/(InAs/GaAs) quantum dot hetero-structure, employing high energy proton irradiation, without any post-annealing treatment. Protons of energy 3-5 MeV with fluence in the range (1.2-7.04) x 10{sup 12} ions/cm{sup 2} were used for irradiation. X-ray diffraction analysis revealed crystalline quality of the GaAs cap layer improves on proton irradiation. Photoluminescence study conducted at low temperature and low laser excitation density proved the presence of non-radiative recombination centers in the system which gets eliminated on proton irradiation. Shift in photoluminescence emission towards higher wavelength upon irradiation substantiated the reduction in strain field existed between GaAs cap layer and InAs/GaAs quantum dots. The enhancement in PL efficiency is thus attributed to the annihilation of defects/non-radiative recombination centers present in GaAs cap layer as well as in InAs/GaAs quantum dots induced by proton irradiation.

  8. Microbial survival rates of Escherichia coli and Deinococcus radiodurans under low temperature, low pressure, and UV-Irradiation conditions, and their relevance to possible Martian life.

    PubMed

    Diaz, Benjamin; Schulze-Makuch, Dirk

    2006-04-01

    Viability rates were determined for microbial populations of Escherichia coli and Deinococcus radiodurans under the environmental stresses of low temperature (-35 degrees C), low-pressure conditions (83.3 kPa), and ultraviolet (UV) irradiation (37 W/m(2)). During the stress tests the organisms were suspended in saltwater soil and freshwater soil media, at variable burial depths, and in seawater. Microbial populations of both organisms were most susceptible to dehydration stress associated with low-pressure conditions, and to UV irradiation. However, suspension in a liquid water medium and burial at larger depths (5 cm) improved survival rates markedly. Our results indicate that planetary surfaces that possess little to no atmosphere and have low water availability do not constitute a favorable environment for terrestrial microorganisms.

  9. Microbial Survival Rates of Escherichia coli and Deinococcus radiodurans Under Low Temperature, Low Pressure, and UV-Irradiation Conditions, and Their Relevance to Possible Martian Life

    NASA Astrophysics Data System (ADS)

    Diaz, Benjamin; Schulze-Makuch, Dirk

    2006-04-01

    Viability rates were determined for microbial populations of Escherichia coli and Deinococcus radiodurans under the environmental stresses of low temperature (-35°C), low-pressure conditions (83.3 kPa), and ultraviolet (UV) irradiation (37 W/m2). During the stress tests the organisms were suspended in saltwater soil and freshwater soil media, at variable burial depths, and in seawater. Microbial populations of both organisms were most susceptible to dehydration stress associated with low-pressure conditions, and to UV irradiation. However, suspension in a liquid water medium and burial at larger depths (5 cm) improved survival rates markedly. Our results indicate that planetary surfaces that possess little to no atmosphere and have low water availability do not constitute a favorable environment for terrestrial microorganisms.

  10. Proton and neutron irradiation effect of Ti: Sapphires

    SciTech Connect

    Wang, G.; Zhang, J.; Yang, J.

    1999-07-01

    Various effects of proton and neutron irradiated Ti: sapphires were studied. Proton irradiation induced F, F{sup +} and V center in Ti: sapphires and 3310 cm{sup -1} infrared absorption, and made ultraviolet absorption edge shift to short wave. Neutron irradiation produced a number of F, F{sup +} and F{sub 2} centers and larger defects in Ti: sapphires, and changed Ti{sup 4+}into Ti{sup 3+} ions. Such valence state variation enhanced characteristic luminescence of Ti: sapphires, and no singular variances of intrinsic fluorescence spectra of Ti: sapphires took place with neutron flux of 1 x 10{sup 17}n/cm{sup 2}, but the fluorescence vanished with neutron flux of 1 x 10{sup 18}n/cm{sup 2} which means the threshold for the concentration of improving Ti{sup 3+} ions by neutron irradiation.

  11. Viability of Cladosporium herbarum spores under 157 nm laser and vacuum ultraviolet irradiation, low temperature (10 K) and vacuum

    SciTech Connect

    Sarantopoulou, E. Stefi, A.; Kollia, Z.; Palles, D.; Cefalas, A. C.; Petrou, P. S.; Bourkoula, A.; Koukouvinos, G.; Kakabakos, S.; Velentzas, A. D.

    2014-09-14

    Ultraviolet photons can damage microorganisms, which rarely survive prolonged irradiation. In addition to the need for intact DNA, cell viability is directly linked to the functionality of the cell wall and membrane. In this work, Cladosporium herbarum spore monolayers exhibit high viability (7%) when exposed to 157 nm laser irradiation (412 kJm⁻²) or vacuum-ultraviolet irradiation (110–180 nm) under standard pressure and temperature in a nitrogen atmosphere. Spore viability can be determined by atomic-force microscopy, nano-indentation, mass, μ-Raman and attenuated reflectance Fourier-transform far-infrared spectroscopies and DNA electrophoresis. Vacuum ultraviolet photons cause molecular damage to the cell wall, but radiation resistance in spores arises from the activation of a photon-triggered signaling reaction, expressed via the exudation of intracellular substances, which, in combination with the low penetration depth of vacuum-ultraviolet photons, shields DNA from radiation. Resistance to phototoxicity under standard conditions was assessed, as was resistance to additional environmental stresses, including exposure in a vacuum, under different rates of change of pressure during pumping time and low (10 K) temperatures. Vacuum conditions were far more destructive to spores than vacuum-ultraviolet irradiation, and UV-B photons were two orders of magnitude more damaging than vacuum-ultraviolet photons. The viability of irradiated spores was also enhanced at 10 K. This work, in addition to contributing to the photonic control of the viability of microorganisms exposed under extreme conditions, including decontamination of biological warfare agents, outlines the basis for identifying bio-signaling in vivo using physical methodologies.

  12. Viability of Cladosporium herbarum spores under 157 nm laser and vacuum ultraviolet irradiation, low temperature (10 K) and vacuum

    NASA Astrophysics Data System (ADS)

    Sarantopoulou, E.; Stefi, A.; Kollia, Z.; Palles, D.; Petrou, P. S.; Bourkoula, A.; Koukouvinos, G.; Velentzas, A. D.; Kakabakos, S.; Cefalas, A. C.

    2014-09-01

    Ultraviolet photons can damage microorganisms, which rarely survive prolonged irradiation. In addition to the need for intact DNA, cell viability is directly linked to the functionality of the cell wall and membrane. In this work, Cladosporium herbarum spore monolayers exhibit high viability (7%) when exposed to 157 nm laser irradiation (412 kJm-2) or vacuum-ultraviolet irradiation (110-180 nm) under standard pressure and temperature in a nitrogen atmosphere. Spore viability can be determined by atomic-force microscopy, nano-indentation, mass, μ-Raman and attenuated reflectance Fourier-transform far-infrared spectroscopies and DNA electrophoresis. Vacuum ultraviolet photons cause molecular damage to the cell wall, but radiation resistance in spores arises from the activation of a photon-triggered signaling reaction, expressed via the exudation of intracellular substances, which, in combination with the low penetration depth of vacuum-ultraviolet photons, shields DNA from radiation. Resistance to phototoxicity under standard conditions was assessed, as was resistance to additional environmental stresses, including exposure in a vacuum, under different rates of change of pressure during pumping time and low (10 K) temperatures. Vacuum conditions were far more destructive to spores than vacuum-ultraviolet irradiation, and UV-B photons were two orders of magnitude more damaging than vacuum-ultraviolet photons. The viability of irradiated spores was also enhanced at 10 K. This work, in addition to contributing to the photonic control of the viability of microorganisms exposed under extreme conditions, including decontamination of biological warfare agents, outlines the basis for identifying bio-signaling in vivo using physical methodologies.

  13. Electronic properties of deep-level defects in proton irradiated AlGaAs-GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Li, S. S.

    1981-01-01

    Deep level transient spectroscopy and capacitance voltage techniques as well as analysis of the forward current voltage (I-V) characteristics and SEM-EIC data were carried out for proton irradiated GaAs solar cells over a wide range of proton energies and proton fluences. Defect and recombination parameters such as defect energy levels and density, carrier capture cross sections and lifetimes as well as diffusion lengths in the undoped n-GaAs LPE layers were determined. Good correlation between these defect parameters and solar cell performance parameters was obtained for GaAs solar cells irradiated by 200 and 290 KeV protons. It was found that 200 to 290 KeV protons will produce the most defects and damages to the GaAs solar cell structure used. The influence of the low temperature (200 to 400 C) periodic thermal annealing on the deep level defects and the performance of the 200 KeV proton irradiated cells is discussed.

  14. Very low temperature irradiation of aliphatic polymers: Role of radical migration on the creation of stable groups (O-127)

    NASA Astrophysics Data System (ADS)

    Mélot, M.; Ngono-Ravache, Y.; Balanzat, E.

    2003-08-01

    We have analysed the influence of temperature, and thus the role of radical motion on the evolution of two in-chain unsaturated bonds, transvinylene, -CH 2-CHCH-CH 2- and trans-trans diene, -CHCH-CHCH-, created in aliphatic polymers submitted to radiations. Results reported here are related to three polymers (PE, EPDM-1,4 hexadiene and EPR) irradiated with high energy ions at 8 and 298 K. Annealing samples, irradiated at 8 K, up to room temperature provides information on the radical migration effect on the creation and the stability of the studied defects. The modifications were followed on line by Fourier transform infrared spectroscopy. The trans-trans diene groups creation necessarily requires radical migration while an in-cage process is efficient for transvinylene groups creation. The radiative destruction of transvinylene groups is clearly induced by radical migration.

  15. Density changes in amorphous Pd{sub 80}Si{sub 20} during low temperature ion irradiation

    SciTech Connect

    Schumacher, G.; Birtcher, R.C.; Rehn, L.E.

    1994-11-01

    Density changes in amorphous Pd{sub 80}Si{sub 20} during ion irradiation below 100K were detected by in situ HVEM measurements of the changes in specimen length as a function of ion fluence. A decrease in mass density as a function of the ion fluence was observed. The saturation value of the change in mass density was determined to be approximately -1.2%.

  16. Low-temperature low-dose neutron irradiation effects on Brush Wellman S65-C and Kawechi Berylco P0 beryllium

    SciTech Connect

    Snead, L.L.

    1998-09-01

    The mechanical property results for two high quality beryllium materials subjected to low temperature, low dose neutron irradiation in water moderated reactors are presented. Materials chosen were the S65-C ITER candidate material produced by Brush Wellman, and Kawecki Berylco Industries P0 beryllium. Both materials were processed by vacuum hot pressing. Mini sheet tensile and thermal diffusivity specimens were irradiated in the temperature range of {approximately}100--275 C from a fast (E > 0.1 MeV) neutron dose of 0.05 to 1.0 {times} 10{sup 25} n/m{sup 2} in the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory and the High Flux Beam Reactor (HFBR) at the Brookhaven National Laboratory. As expected from earlier work on beryllium, both materials underwent significant embrittlement with corresponding reduction in ductility and increased strength. Both thermal diffusivity and volumetric expansion were measured and found to be negligible in this temperature and fluence range. Of significance from this work is that while both materials rapidly embrittle at these ITER relevant irradiation conditions, some ductility (>1--2%) remains, which contrasts with a body of earlier work including recent work on the Brush-Wellman S65-C material irradiated to slightly higher neutron fluence.

  17. Interstitial-Mediated Diffusion in Germanium under Proton Irradiation

    NASA Astrophysics Data System (ADS)

    Bracht, H.; Schneider, S.; Klug, J. N.; Liao, C. Y.; Hansen, J. Lundsgaard; Haller, E. E.; Larsen, A. Nylandsted; Bougeard, D.; Posselt, M.; Wündisch, C.

    2009-12-01

    We report experiments on the impact of 2.5 MeV proton irradiation on self-diffusion and dopant diffusion in germanium (Ge). Self-diffusion under irradiation reveals an unusual depth independent broadening of the Ge isotope multilayer structure. This behavior and the observed enhanced diffusion of B and retarded diffusion of P demonstrates that an interstitial-mediated diffusion process dominates in Ge under irradiation. This fundamental finding opens up unique ways to suppress vacancy-mediated diffusion in Ge and to solve the donor deactivation problem that hinders the fabrication of Ge-based nanoelectronic devices.

  18. Defect generation in Cu(In,Ga)Se2 heterojunction solar cells by high-energy electron and proton irradiation

    NASA Astrophysics Data System (ADS)

    Jasenek, A.; Rau, U.

    2001-07-01

    We investigate irradiation-induced defects in high-efficiency Cu(In,Ga)Se2/CdS/ZnO heterojunction solar cells after electron irradiation with energies of 0.5, 1, and 3 MeV and after 4 MeV proton irradiation. We use electron and proton fluences of more than 1018cm-2 and up to 1014cm-2, respectively. The reduction of the solar cell efficiency in all experiments is predominantly caused by a loss ΔVOC of the open circuit voltage VOC. An analytical model describes ΔVOC in terms of radiation-induced defects enhancing recombination in the Cu(In,Ga)Se2 absorber material. From our model, we extract defect introduction rates for recombination centers in Cu(In,Ga)Se2 for the respective particles and energies. We directly monitor the defect generation of these radiation-induced defects by admittance spectroscopy. The decrease of effective doping density in the Cu(In,Ga)Se2 absorber layer under particle irradiation is analyzed with capacitance voltage measurements at low temperatures. Furthermore, data on the relative damage coefficients for high-energy electron irradiation in Cu(In,Ga)Se2 solar cells are presented. All data, from electron as well as proton irradiations, merge to a single characteristic degradation curve.

  19. Isotopic anomalies and proton irradiation in the early solar system

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.; Dwek, E.; Woosley, S. E.

    1977-01-01

    Nuclear cross sections relevant to the various isotopic-abundance anomalies found in solar-system objects are evaluated in an attempt to set constraints on the hypothesized mechanism of irradiation of forming planetesimals by energetic protons from the young sun. A power-law proton spectrum is adopted, attention is restricted to proton energies less than about 20 MeV, and average cross sections are calculated for several reactions that might be expected to lead to the observed anomalies. The following specific anomalies are examined in detail: Al-26, Na-22, Xe-126, I-129, Kr-80, V-50, Nb-92, La-138, Ta-180, Hg-196, K-40, Ar-36, O-17, O-18, N-15, C-13, Li, Be, and B. It is suggested that the picture of presolar-grain carriers accounts for the facts more naturally than do irradiation models.

  20. Central nervous system effects of whole-body proton irradiation.

    PubMed

    Sweet, Tara Beth; Panda, Nirlipta; Hein, Amy M; Das, Shoshana L; Hurley, Sean D; Olschowka, John A; Williams, Jacqueline P; O'Banion, M Kerry

    2014-07-01

    Space missions beyond the protection of Earth's magnetosphere expose astronauts to an environment that contains ionizing proton radiation. The hazards that proton radiation pose to normal tissues, such as the central nervous system (CNS), are not fully understood, although it has been shown that proton radiation affects the neurogenic environment, killing neural precursors and altering behavior. To determine the time and dose-response characteristics of the CNS to whole-body proton irradiation, C57BL/6J mice were exposed to 1 GeV/n proton radiation at doses of 0-200 cGy and behavioral, physiological and immunohistochemical end points were analyzed over a range of time points (48 h-12 months) postirradiation. These experiments revealed that proton radiation exposure leads to: 1. an acute decrease in cell division within the dentate gyrus of the hippocampus, with significant differences detected at doses as low as 10 cGy; 2. a persistent effect on proliferation in the subgranular zone, at 1 month postirradiation; 3. a decrease in neurogenesis at doses as low as 50 cGy, at 3 months postirradiation; and 4. a decrease in hippocampal ICAM-1 immunoreactivity at doses as low as 10 cGy, at 1 month postirradiation. The data presented contribute to our understanding of biological responses to whole-body proton radiation and may help reduce uncertainty in the assessment of health risks to astronauts. These findings may also be relevant to clinical proton beam therapy. PMID:24937778

  1. Intraocular inflammation after proton beam irradiation for uveal melanoma

    PubMed Central

    Lumbroso, L.; Desjardins, L.; Levy, C.; Plancher, C.; Frau, E.; D'Hermies, F.; Schlienger, P.; Mammar, H.; Delacroix, S.; Nauraye, C.; Ferrand, R.; Desblancs, C.; Mazal, A.; Asselain, B.

    2001-01-01

    AIM—To describe the inflammatory reaction that can occur following proton beam irradiation of uveal melanomas based on a large series of patients and to try to determine the risk factors for this reaction.
METHODS—Data from a cohort of patients with uveal melanoma treated by proton beam irradiation between 1991 and 1994 were analysed. The presence of inflammation was recorded and evaluated. Kaplan-Meier estimates and statistical analysis of general and tumour related risk factors were performed.
RESULTS—28% of patients treated during this period presented with ocular inflammation (median follow up 62 months). Risks factors were essentially tumour related and were correlated with larger lesions (height > 5 mm, diameter > 12 mm, volume > 0.4 cm3). Multivariate analysis identified initial tumour height and irradiation of a large volume of the eye as the two most important risk factors. Ocular inflammation usually consisted of mild anterior uveitis, resolving rapidly after topical steroids and cycloplegics. The incidence of inflammation after proton beam irradiation of melanomas seems higher than previously reported and is related to larger lesions. Evidence of inflammation associated with uveal melanoma has been described and seems to be associated with tumour necrosis (spontaneous or after irradiation). The appearance of transient inflammation during the follow up of these patients may be related to the release of inflammatory cytokines during tumour necrosis.
CONCLUSION—Inflammation following proton beam irradiation is not unusual. It is correlated with larger initial tumours and may be related to tumour necrosis.

 PMID:11673294

  2. Radiation Sterilization of Prototype Military Foods: Low-Temperature Irradiation of Codfish Cake, Corned Beef, and Pork Sausage 1

    PubMed Central

    Anellis, Abe; Berkowitz, D.; Swantak, W.; Strojan, C.

    1972-01-01

    “Screening” packs comprising 10 lots each of codfish cake, corned beef, and pork sausage, each lot containing about 106 spores of a different strain (five type A and five type B) of Clostridium botulinum per can, were irradiated at −30 ± 10 C with a series of increasing doses (20 replicate cans/dose) of 60Co gamma rays. The cans were incubated for 3 months at 30 C and examined for swelling, toxin, and recoverable botulinal cells. Based on the latter criterion of spoilage, median lethal dose (LD50) and D values were estimated for each strain in each food. The most resistant strain in codfish cake, corned beef, and pork sausage was, respectively, 53B, 77A, and 41B. There was no clear-cut trend in the comparative order of resistance between the two antigenic types among the three foods. LD50 values gave essentially the same order of resistances as the D values and may be used interchangeably with the latter for the 10 test organisms. “Clearance” packs consisting of the most resistant strain (about 107 spores/can) with its respective food were irradiated with a variety of doses at −30 ± 10 C, using 100 replicate cans/dose (about 109 spores/dose). These packs were incubated for 6 months at 30 C and assayed for the three types of spoilage. Based on recoverable cells, the experimental sterilizing doses (ESD) for codfish cake, corned beef, and pork sausage were 2.5< ESD ≤ 3.0, 2.0 < ESD ≤ 2.5, and 1.5 < ESD ≤ 2.0 Mrad, in that order. Assuming exponential spore death, the 12D values, or minimal radiation doses (MRD), were 3.24, 2.44, and 2.65 Mrad, respectively. Estimation of the MRD values by a method which assumes that spore death in the cans follows a normal distribution, yielded 3.09, 2.57, and 2.39 Mrad, respectively. Weibull analyis of the pooled 10-strain viable cell spoilage data of the screening packs for codfish cake or corned beef suggested that spore death in the cans follows a normal distribution yielded 3.09, 2.57, pooled data were not

  3. Performance of candidate SEPS solar cells as a function of low temperature and low intensity exposure and 1 MeV electron irradiation

    NASA Technical Reports Server (NTRS)

    Whitaker, A. F.; Little, S. A.; Rives, C. J.; Wagner, P. E.

    1981-01-01

    The behavior of 144 high-performance shallow-junction silicon solar cells under conditions of low temperature and intensity was examined. The cells represented nine combinations of thickness, base resistivity, front surface texture, and rear surface treatment. At least 16 cells of each type were individually tested both as active elements under light levels between 0.04 and 1.0 solar constant and in the dark as passive rectifiers under external forward bias. One cell type was also irradiated with 1 MeV electrons up to 2.7 x 10 to the 15th e/sq cm. The inferior cells demonstrated high ohmic and/or non-ohmic shunting. No series resistance or Schottky barrier effects were observed. Fluences beyond 10 to the 13th e/sq cm lowered cell current, probably by increasing volume recombination.

  4. Performance of candidate SEPS solar cells as a function of low temperature and low intensity exposure and 1 MeV electron irradiation

    NASA Astrophysics Data System (ADS)

    Whitaker, A. F.; Little, S. A.; Rives, C. J.; Wagner, P. E.

    1981-04-01

    The behavior of 144 high-performance shallow-junction silicon solar cells under conditions of low temperature and intensity was examined. The cells represented nine combinations of thickness, base resistivity, front surface texture, and rear surface treatment. At least 16 cells of each type were individually tested both as active elements under light levels between 0.04 and 1.0 solar constant and in the dark as passive rectifiers under external forward bias. One cell type was also irradiated with 1 MeV electrons up to 2.7 x 10 to the 15th e/sq cm. The inferior cells demonstrated high ohmic and/or non-ohmic shunting. No series resistance or Schottky barrier effects were observed. Fluences beyond 10 to the 13th e/sq cm lowered cell current, probably by increasing volume recombination.

  5. Mesoscopic inhomogeneity creation in YBa2Cu3O7-y thin film by swift heavy ion irradiation at low temperature

    NASA Astrophysics Data System (ADS)

    Biswal, R.; John, J.; Raychaudhuri, P.; Behera, D.; Mohanty, T.; Avasthi, D. K.; Kanjilal, D.; Mishra, N. C.

    2011-09-01

    In the present study, we report the modification of pulsed laser deposited c-axis oriented thin films of YBa2Cu3O7-y (YBCO) in a cylindrical region around the path of swift heavy ions (SHIs). Our in situ temperature-dependent resistivity measurement and in situ low-temperature X-ray diffraction (XRD) study on YBCO irradiated at liquid nitrogen temperature with 200 MeV Ag ions shows that the SHI-induced secondary electrons selectively create point defects at CuO basal chains of YBCO. Beyond a critical fluence (∼1012 ions/cm2), the radially strained region around the amorphous latent tracks estimated from full width at half-maximum of (00l) XRD peaks tends to overlap, and a two-step superconducting transition evolves instead of a single transition in the in situ resistivity measurement.

  6. Helium and hydrogen generation in pure metals irradiated with high-energy protons and spallation neutrons in LANSCE

    NASA Astrophysics Data System (ADS)

    Oliver, B. M.; James, M. R.; Garner, F. A.; Maloy, S. A.

    2002-12-01

    High-power spallation neutron sources will require accurate estimates of cross-sections for generation of He and H in structural materials. At high-proton energies, very high levels of gas atoms are generated in all constituents of typical iron-based and nickel-based structural alloys, with He typically ˜150 appm/dpa and H at levels ˜3-5 times higher. Improved estimates of these cross-sections have been derived from a series of irradiations conducted at relatively low temperatures (<100 °C) in the Los Alamos Neutron Science Center as part of a test program supporting the Accelerator Production of Tritium Program. Pure metal dosimetry foils were irradiated in two different spectra ranging from ˜800 MeV protons to a mixed distribution of both protons and spallation neutrons. Most of the gas production was due to spallation reactions with the proton beam, although gas and especially damage production from lower-energy spallation neutrons became more significant at the mixed proton/neutron location. The measured He concentrations are similar to those derived in other proton environments, but larger by about a factor of two than those calculated using the LAHET/MCNPX code system. Unlike He, the measured H retention levels are affected by diffusional losses, but H is still retained at rather high concentrations, allowing a lower bound estimate of the H generation cross-sections.

  7. EPR detected polarization transfer between Gd3+ and protons at low temperature and 3.3 T: the first step of dynamic nuclear polarization.

    PubMed

    Nagarajan, Vijayasarathi; Hovav, Yonatan; Feintuch, Akiva; Vega, Shimon; Goldfarb, Daniella

    2010-06-01

    Electron-electron double resonance pulsed electron paramagnetic resonance (EPR) at 95 GHz (3.3 T) is used to follow the dynamics of the electron spin polarization during the first stages of dynamic nuclear polarization in solids. The experiments were performed on a frozen solution of Gd(+3) (S=7/2) in water/glycerol. Focusing on the central vector -1/2 --> vector +1/2 transition we measured the polarization transfer from the Gd(3+) electron spin to the adjacent (1)H protons. The dependence of the echo detected EPR signal on the length of the microwave irradiation at the EPR "forbidden" transition corresponding to an electron and a proton spin flip is measured for different powers, showing dynamics on the microsecond to millisecond time scales. A theoretical model based on the spin density matrix formalism is suggested to account for this dynamics. The central transition of the Gd(3+) ion is considered as an effective S = 1/2 system and is coupled to (1)H (I = 1/2) nuclei. Simulations based on a single electron-single nucleus four level system are shown to deviate from the experimental results and an alternative approach taking into account the more realistic multinuclei picture is shown to agree qualitatively with the experiments.

  8. Orientation dependency of mechanical properties of 1950`s vintage Type 304 stainless steel weldment components before and after low temperature neutron irradiation

    SciTech Connect

    Sindelar, R.L.; Caskey, G.R. Jr.

    1992-12-31

    Databases of mechanical properties for both the piping and reactor vessels at the Savannah River Site (SRS) were developed from weldment components (base, weld, and weld heat-affected-zone (HAZ)) of archival piping specimens in the unirradiated and irradiated conditions. Tensile, Charpy V-notch (CVN), and Compact Tension C(T) specimens were tested at 25 and 125C before and after irradiation at low temperatures (90 to 150C) to levels of 0.065 to 2.1 dpa. irradiation hardened the weldment components and reduced the absorbed energy and toughness properties from the unirradiated values. A marked difference in the Charpy V-notch absorbed energy and the elastic-plastic fracture toughness (J{sub IC}) was observed for both the base and HAZ components with the C-L orientation being lower in toughness than the L-C orientation in both the unirradiated and irradiated conditions. Fracture surface examination of the base and HAZ components of unirradiated C(T) specimens showed a ``channel`` morphology in the fracture surfaces of the C-L specimens, whereas equiaxed ductile rupture occurred in the L-C specimens. Chromium carbide precipitation in the HAZ component reduced the fracture toughness of the C-L and L-C specimens compared to the respective base component C-L and L-C specimens. Optical metallography of the piping materials showed stringers of second phase particles parallel to the rolling direction along with a banding or modulation in the microchemistry perpendicular to the pipe axis or rolling direction of the plate material.

  9. Orientation dependency of mechanical properties of 1950's vintage Type 304 stainless steel weldment components before and after low temperature neutron irradiation

    SciTech Connect

    Sindelar, R.L.; Caskey, G.R. Jr.

    1992-01-01

    Databases of mechanical properties for both the piping and reactor vessels at the Savannah River Site (SRS) were developed from weldment components (base, weld, and weld heat-affected-zone (HAZ)) of archival piping specimens in the unirradiated and irradiated conditions. Tensile, Charpy V-notch (CVN), and Compact Tension C(T) specimens were tested at 25 and 125C before and after irradiation at low temperatures (90 to 150C) to levels of 0.065 to 2.1 dpa. irradiation hardened the weldment components and reduced the absorbed energy and toughness properties from the unirradiated values. A marked difference in the Charpy V-notch absorbed energy and the elastic-plastic fracture toughness (J[sub IC]) was observed for both the base and HAZ components with the C-L orientation being lower in toughness than the L-C orientation in both the unirradiated and irradiated conditions. Fracture surface examination of the base and HAZ components of unirradiated C(T) specimens showed a channel'' morphology in the fracture surfaces of the C-L specimens, whereas equiaxed ductile rupture occurred in the L-C specimens. Chromium carbide precipitation in the HAZ component reduced the fracture toughness of the C-L and L-C specimens compared to the respective base component C-L and L-C specimens. Optical metallography of the piping materials showed stringers of second phase particles parallel to the rolling direction along with a banding or modulation in the microchemistry perpendicular to the pipe axis or rolling direction of the plate material.

  10. Production of sodium-22 from proton irradiated aluminum

    DOEpatents

    Taylor, Wayne A.; Heaton, Richard C.; Jamriska, David J.

    1996-01-01

    A process for selective separation of sodium-22 from a proton irradiated minum target including dissolving a proton irradiated aluminum target in hydrochloric acid to form a first solution including aluminum ions and sodium ions, separating a portion of the aluminum ions from the first solution by crystallization of an aluminum salt, contacting the remaining first solution with an anion exchange resin whereby ions selected from the group consisting of iron and copper are selectively absorbed by the anion exchange resin while aluminum ions and sodium ions remain in solution, contacting the solution with an cation exchange resin whereby aluminum ions and sodium ions are adsorbed by the cation exchange resin, and, contacting the cation exchange resin with an acid solution capable of selectively separating the adsorbed sodium ions from the cation exchange resin while aluminum ions remain adsorbed on the cation exchange resin is disclosed.

  11. Superconductivity in MgB2 irradiated with energetic protons

    NASA Astrophysics Data System (ADS)

    Sandu, Viorel; Craciun, Liviu; Ionescu, Alina Marinela; Aldica, Gheorghe; Miu, Lucica; Kuncser, Andrei

    2016-09-01

    A series of MgB2 samples were irradiated with protons of 11.3 and 13.2 MeV. Magnetization data shows an insignificant reduction of the critical temperatures but a continuous decrease of the Meissner fraction with increasing fluence or energy. All samples show a consistent improvement of the critical current density compared to the virgin sample and an increase of the pinning energy at high fields as resulted from relaxation data.

  12. High Rate Proton Irradiation of 15mm Muon Drifttubes

    NASA Astrophysics Data System (ADS)

    Zibell, A.; Biebel, O.; Hertenberger, R.; Ruschke, A.; Schmitt, Ch.; Kroha, H.; Bittner, B.; Schwegler, P.; Dubbert, J.; Ott, S.

    2012-08-01

    Future LHC luminosity upgrades will significantly increase the amount of background hits from photons, neutrons 11.11d protons in the detectors of the ATLAS muon spectrometer. At the proposed LHC peak luminosity of 5\\cdot 1034(1)/(cm2s), background hit rates of more than 10(kHz)/(cm2) are expected in the innermost forward region, leading to a loss of performance of the current tracking chambers. Based on the ATLAS Monitored Drift Tube chambers, a new high rate capable drift tube detecor using tubes with a reduced diameter of 15mm was developed. To test the response to highly ionizing particles, a prototype chamber of 46 15mm drift tubes was irradiated with a 20 MeV proton beam at the tandem accelerator at the Maier-Leibnitz Laboratory, Munich. Three tubes in a planar layer were irradiated while all other tubes were used for reconstruction of cosmic muon tracks through irradiated and nonirradiated parts of the chamber. To determine the rate capability of the 15mm drifttubes we investigated the effect of the proton hit rate on pulse height, efficiency and spatial resolution of the cosmic muon signals.

  13. Proteomic Analysis of Proton Beam Irradiated Human Melanoma Cells

    PubMed Central

    Kedracka-Krok, Sylwia; Jankowska, Urszula; Elas, Martyna; Sowa, Urszula; Swakon, Jan; Cierniak, Agnieszka; Olko, Pawel; Romanowska-Dixon, Bozena; Urbanska, Krystyna

    2014-01-01

    Proton beam irradiation is a form of advanced radiotherapy providing superior distributions of a low LET radiation dose relative to that of photon therapy for the treatment of cancer. Even though this clinical treatment has been developing for several decades, the proton radiobiology critical to the optimization of proton radiotherapy is far from being understood. Proteomic changes were analyzed in human melanoma cells treated with a sublethal dose (3 Gy) of proton beam irradiation. The results were compared with untreated cells. Two-dimensional electrophoresis was performed with mass spectrometry to identify the proteins. At the dose of 3 Gy a minimal slowdown in proliferation rate was seen, as well as some DNA damage. After allowing time for damage repair, the proteomic analysis was performed. In total 17 protein levels were found to significantly (more than 1.5 times) change: 4 downregulated and 13 upregulated. Functionally, they represent four categories: (i) DNA repair and RNA regulation (VCP, MVP, STRAP, FAB-2, Lamine A/C, GAPDH), (ii) cell survival and stress response (STRAP, MCM7, Annexin 7, MVP, Caprin-1, PDCD6, VCP, HSP70), (iii) cell metabolism (TIM, GAPDH, VCP), and (iv) cytoskeleton and motility (Moesin, Actinin 4, FAB-2, Vimentin, Annexin 7, Lamine A/C, Lamine B). A substantial decrease (2.3 x) was seen in the level of vimentin, a marker of epithelial to mesenchymal transition and the metastatic properties of melanoma. PMID:24392146

  14. Effect of proton irradiation on superconductivity in optimally doped BaFe2(As1-xPx)2 single crystals

    DOE PAGES

    Smylie, M. P.; Leroux, M.; Fang, L.; Chmaissem, Omar H.; Claus, H.; Kayani, A.; Snezhko, A.; Welp, U.; Kwok, W. -K.; Mishra, V.; et al

    2016-03-10

    Irradiation with 4 MeV protons was used to systematically introduce defects in single crystals of the iron-arsenide superconductor BaFe2(As1-xPx)2, x = 0.33. The effect of disorder on the low-temperature behavior of the London penetration depth λ(T) and transition temperature Tc was investigated. In nearly optimally doped samples with Tc ~ 29 K, signatures of a superconducting gap with nodes were observed. Contrary to previous reports on electron-irradiated crystals, we do not see a disorder-driven lifting of accidental nodes, and we observe that proton-induced defects are weaker pair breakers than electron-induced defects. Lastly, we attribute our findings to anisotropic electron scatteringmore » caused by proton irradiation defects.« less

  15. Magnetic properties of point defects in proton irradiated diamond

    NASA Astrophysics Data System (ADS)

    Makgato, T. N.; Sideras-Haddad, E.; Ramos, M. A.; García-Hernández, M.; Climent-Font, A.; Zucchiatti, A.; Muñoz-Martin, A.; Shrivastava, S.; Erasmus, R.

    2016-09-01

    We investigate the magnetic properties of ultra-pure type-IIa diamond following irradiation with proton beams of ≈1-2 MeV energy. SQUID magnetometry indicate the formation of Curie type paramagnetism according to the Curie law. Raman and Photoluminescence spectroscopy measurements show that the primary structural features created by proton irradiation are the centers: GR1, ND1, TR12 and 3H. The Stopping and Range of Ions in Matter (SRIM) Monte Carlo simulations together with SQUID observations show a strong correlation between vacancy production, proton fluence and the paramagnetic factor. At an average surface vacancy spacing of ≈1-1.6 nm and bulk (peak) vacancy spacing of ≈0.3-0.5 nm Curie paramagnetism is induced by formation of ND1 centres with an effective magnetic moment μeff~(0.1-0.2)μB. No evidence of long range magnetic ordering is observed in the temperature range 4.2-300 K.

  16. Head and neck tumors after energetic proton irradiation in rats

    NASA Astrophysics Data System (ADS)

    Wood, D.; Cox, A.; Hardy, K.; Salmon, Y.; Trotter, R.

    1994-10-01

    This is a two-year progress report on a life span dose-response study of brain tumor risk at moderate to high doses of energetic protons. It was initiated because a joint NASA/USAF life span study of rhesus monkeys that were irradiated with 55-MeV protons (average surface dose, 3.5 Gy) indicated that the incidence of brain tumors per unit surface absorbed dose was over 19 times that of the human tinea capitis patients whose heads were exposed to 100 kv x-rays. Examination of those rats that died in the two-year interval after irradiation of the head revealed a linear dose-response for total head and neck tumor incidence in the dose range of 0-8.5 Gy. The exposed rats had a greater incidence of pituitary chromophobe adenomas, epithelial and mesothelial cell tumors than the unexposed controls but the excessive occurrence of malignant gliomas that was observed in the monkeys was absent in the rats. The estimated dose required to double the number of all types of head and neck tumors was 5.2 Gy. The highest dose, 18 Gy, resulted in high mortality due to obstructive squamous metaplasia at less than 50 weeks, prompting a new study of the relative bological effectiveness of high energy protons in producing this lesion.

  17. Proton irradiation creep of FM steel T91

    NASA Astrophysics Data System (ADS)

    Xu, Cheng; Was, Gary S.

    2015-04-01

    Ferritic-martensitic (FM) steel T91 was subjected to irradiation with 3 MeV protons while under load at stresses of 100-200 MPa, temperatures between 400 °C and 500 °C, and dose rates between 1.4 × 10-6 dpa/s and 5 × 10-6 dpa/s to a total dose of less than 1 dpa. Creep behavior was analyzed for parametric dependencies. The temperature dependence was found to be negligible between 400 °C and 500 °C, and the dose rate dependence was observed to be linear. Creep rate was proportional to stress at low stress values and varied with stress to the power 14 above 160 MPa. The large stress exponent of the proton irradiation creep experiments under high stress suggested that dislocation glide was driving both thermal and irradiation creep. Microstructure observations of anisotropic dislocation loops also contributed to the total creep strain. After subtracting the power law creep and anisotropic dislocation loop contributions, the remaining creep strain was accounted for by dislocation climb enabled by stress induced preferential absorption (SIPA) and preferential dislocation glide (PAG).

  18. Recovery behavior of high purity cubic SiC polycrystals by post-irradiation annealing up to 1673 K after low temperature neutron irradiation

    NASA Astrophysics Data System (ADS)

    Idris, Mohd Idzat; Yamazaki, Saishun; Yoshida, Katsumi; Yano, Toyohiko

    2015-10-01

    Two kinds of high purity cubic (β) SiC polycrystals, PureBeta-SiC and CVD-SiC, were irradiated in the BR2 reactor (Belgium) up to a fluence of 2.0-2.5 × 1024 (E > 0.1 MeV) at 333-363 K. Changes in macroscopic lengths were examined by post-irradiation thermal annealing using a precision dilatometer up to 1673 K with a step-heating method. The specimen was held at each temperature step for 6 h and the change in length of the specimen was recorded during each isothermal annealing step from 373 K to 1673 K with 50 K increments. The recovery curves were analyzed with the first order model, and rate constants at each annealing step were obtained. Recovery of defects, induced by neutron irradiation in high purity β-SiC, has four stages of different activation energies. At 373-573 K, the activation energy of PureBeta-SiC and CVD-SiC was in the range of 0.17-0.24 eV and 0.12-0.14 eV; 0.002-0.04 eV and 0.006-0.04 eV at 723-923 K; 0.20-0.27 eV and 0.26-0.31 eV at 923-1223 K; and 1.37-1.38 eV and 1.26-1.29 eV at 1323-1523 K, respectively. Below ∼1223 K the recombination occurred possibly for closely positioned C and Si Frenkel pairs, and no long range migration is deemed essential. Nearly three-fourths of recovery, induced by neutron irradiation, occur by this mechanism. In addition, at 1323-1523 K, recombination of slightly separated C Frenkel pairs and more long-range migration of Si interstitials may have occurred for PureBeta-SiC and CVD-SiC specimens. Migration of both vacancies may be restricted up to ∼1523 K. Comparing to hexagonal α-SiC, high purity β-SiC recovered more quickly in the lower annealing temperature range of less than 873 K, in particular less than 573 K.

  19. LISA PathFinder radiation monitor proton irradiation test results

    NASA Astrophysics Data System (ADS)

    Mateos, I.; Diaz-Aguiló, M.; Gibert, F.; Grimani, C.; Hollington, D.; Lloro, I.; Lobo, A.; Nofrarias, M.; Ramos-Castro, J.

    2012-06-01

    The design of the Radiation Monitor in the LISA Technology Package on board LISA Pathnder is based on two silicon PIN diodes, placed parallel to each other in a telescopic configuration. One of them is able to record spectral information of the particle hitting the diode. A test campaign for the flight model Radiation Monitor was done in the Paul Scherrer Institute Proton Irradiation Facility in September 2010. Its purpose was to check correct functionality of the Radiation Monitor under real high energy proton fluxes. Here we present the results of the experiments done and their assessment by means of a simulated flight model geometry using GEANT4 toolkit. No deviation from nominal RM performance was detected, which means the instrument is fully ready for flight.

  20. Ferromagnetism in proton irradiated 4H-SiC single crystal

    SciTech Connect

    Zhou, Ren-Wei; Wang, Hua-Jie; Chen, Wei-Bin; Li, Fei; Liu, Xue-Chao Zhuo, Shi-Yi; Shi, Er-Wei

    2015-04-15

    Room-temperature ferromagnetism is observed in proton irradiated 4H-SiC single crystal. An initial increase in proton dose leads to pronounced ferromagnetism, accompanying with obvious increase in vacancy concentration. Further increase in irradiation dose lowers the saturation magnetization with the decrease in total vacancy defects due to the defects recombination. It is found that divacancies are the mainly defects in proton irradiated 4H-SiC and responsible for the observed ferromagnetism.

  1. Proton irradiation effects on the thermoelectric properties in single-crystalline Bi nanowires

    SciTech Connect

    Chang, Taehoo; Kim, Jeongmin; Song, Min-Jung; Lee, Wooyoung

    2015-05-15

    The effects of proton irradiation on the thermoelectric properties of Bi nanowires (Bi-NWs) were investigated. Single crystalline Bi-NWs were grown by the on-film formation of nanowires method. The devices based on individual Bi-NWs were irradiated with protons at different energies. The total number of displaced atoms was estimated using the Kinchin-Pease displacement model. The electric conductivity and Seebeck coefficient in the Bi-NW devices were investigated before and after proton irradiation at different temperatures. Although the Seebeck coefficient remained stable at various irradiation energies, the electrical conductivity significantly declined with increasing proton energy up to 40 MeV.

  2. Optimized enzymatic dual functions of PaPrx protein by proton irradiation

    PubMed Central

    Park, Chul-Hong; Lee, Seung Sik; Kim, Kye Ryung; Jung, Myung Hwan; Lee, Sang Yeol; Cho, Eun Ju; Singh, Sudhir; Chung, Byung Yeoup

    2014-01-01

    We investigated the effects of proton irradiation on the function and structure of the Pseudomonas aeruginosa peroxiredoxin (PaPrx). Polyacrylamide gel demonstrated that PaPrx proteins exposed to proton irradiation at several doses exhibited simultaneous formation of high molecular weight (HMW) complexes and fragmentation. Size-exclusion chromatography (SEC) analysis revealed that the number of fragments and very low molecular weight (LMW) structures increased as the proton irradiation dose increased. The peroxidase activity of irradiated PaPrx was preserved, and its chaperone activity was significantly increased by increasing the proton irradiation dose. The chaperone activity increased about 3–4 fold after 2.5 kGy proton irradiation, compared with that of non-irradiated PaPrx, and increased to almost the maximum activity after 10 kGy proton irradiation. We previously obtained functional switching in PaPrx proteins, by using gamma rays and electron beams as radiation sources, and found that the proteins exhibited increased chaperone activity but decreased peroxidase activity. Interestingly, in this study we newly found that proton irradiation could enhance both peroxidase and chaperone activities. Therefore, we can suggest proton irradiation as a novel protocol for conserved 2-Cys protein engineering. PMID:23753570

  3. Deficiency in Homologous Recombination Renders Mammalian Cells More Sensitive to Proton Versus Photon Irradiation

    SciTech Connect

    Grosse, Nicole; Fontana, Andrea O.; Hug, Eugen B.; Lomax, Antony; Coray, Adolf; Augsburger, Marc; Paganetti, Harald; Sartori, Alessandro A.; Pruschy, Martin

    2014-01-01

    Purpose: To investigate the impact of the 2 major DNA repair machineries on cellular survival in response to irradiation with the 2 types of ionizing radiation. Methods and Materials: The DNA repair and cell survival endpoints in wild-type, homologous recombination (HR)-deficient, and nonhomologous end-joining-deficient cells were analyzed after irradiation with clinically relevant, low-linear energy transfer (LET) protons and 200-keV photons. Results: All cell lines were more sensitive to proton irradiation compared with photon irradiation, despite no differences in the induction of DNA breaks. Interestingly, HR-deficient cells and wild-type cells with small interfering RNA-down-regulated Rad51 were markedly hypersensitive to proton irradiation, resulting in an increased relative biological effectiveness in comparison with the relative biological effectiveness determined in wild-type cells. In contrast, lack of nonhomologous end-joining did not result in hypersensitivity toward proton irradiation. Repair kinetics of DNA damage in wild-type cells were equal after both types of irradiation, although proton irradiation resulted in more lethal chromosomal aberrations. Finally, repair kinetics in HR-deficient cells were significantly delayed after proton irradiation, with elevated amounts of residual γH2AX foci after irradiation. Conclusion: Our data indicate a differential quality of DNA damage by proton versus photon irradiation, with a specific requirement for homologous recombination for DNA repair and enhanced cell survival. This has potential relevance for clinical stratification of patients carrying mutations in the DNA damage response pathways.

  4. Delocalized Plastic Flow in Proton-Irradiated Monolithic Metallic Glasses

    PubMed Central

    Heo, Jaewon; Kim, Sunghwan; Ryu, Seunghwa; Jang, Dongchan

    2016-01-01

    Creating new materials with novel properties through structural modification is the Holy Grail of materials science. The range of targetable structures for amplification of mechanical properties in metallic glasses would include types of atomic short range orders at the smallest scale through compositions or morphologies of phases in composites. Even though the usefulness of the latter approach has been successfully demonstrated in the past decades, the feasibility of the former has been incompletely proved with only marginal property improvements reported within experimentally-accessible atomic-level structural changes. Here, we report the significant enhancement of deformability in Zr-based monolithic metallic glass only through the atomic disordering by proton irradiation without altering any other structural traits. Metallic glass nanopillars that originally failed catastrophically without any notable plasticity become capable of attaining more than 30% uniaxial plastic strain accommodated by homogeneous deformation when irradiated to ~1 displacement per atom (DPA). We discuss the atomistic origin of this improved plasticity in terms of density and spatial distributions of icosahedral short range order influenced by irradiation. PMID:26988265

  5. Proton irradiation of the CIS115 for the JUICE mission

    NASA Astrophysics Data System (ADS)

    Soman, M. R.; Allanwood, E. A. H.; Holland, A. D.; Winstone, G. P.; Gow, J. P. D.; Stefanov, K.; Leese, M.

    2015-09-01

    The CIS115 is one of the latest CMOS Imaging Sensors designed by e2v technologies, with 1504x2000 pixels on a 7 μm pitch. Each pixel in the array is a pinned photodiode with a 4T architecture, achieving an average dark current of 22 electrons pixel-1 s-1 at 21°C measured in a front-faced device. The sensor aims for high optical sensitivity by utilising e2v's back-thinning and processing capabilities, providing a sensitive silicon thickness approximately 9 μm to 12 μm thick with a tuned anti-reflective coating. The sensor operates in a rolling shutter mode incorporating reset level subtraction resulting in a mean pixel readout noise of 4.25 electrons rms. The full well has been measured to be 34000 electrons in a previous study, resulting in a dynamic range of up to 8000. These performance characteristics have led to the CIS115 being chosen for JANUS, the high-resolution and wide-angle optical camera on the JUpiter ICy moon Explorer (JUICE). The three year science phase of JUICE is in the harsh radiation environment of the Jovian magnetosphere, primarily studying Jupiter and its icy moons. Analysis of the expected radiation environment and shielding levels from the spacecraft and instrument design predict the End Of Life (EOL) displacement and ionising damage for the CIS115 to be equivalent to 1010 10 MeV protons cm-2 and 100 krad(Si) respectively. Dark current and image lag characterisation results following initial proton irradiations are presented, detailing the initial phase of space qualification of the CIS115. Results are compared to the pre-irradiation performance and the instrument specifications and further qualification plans are outlined.

  6. Microstructure evolution in proton-irradiated austenitic Fe-Cr-Ni alloys under LWR core conditions

    NASA Astrophysics Data System (ADS)

    Gan, Jian

    1999-11-01

    Irradiation-induced microstructure of austenitic stainless steel was investigated using proton irradiation. High-purity alloys of Fe-20Cr-9Ni (UHP 304 SS), Fe-20Cr-24Ni and Ni-18Cr-9Fe were irradiated using 3.2 MeV protons at a dose rate of 7 × 10-6 dpa/s between 300°C and 600°C. The irradiation produced a microstructure consisting of dislocation loops and voids. The dose and temperature dependence of the number density and size of dislocation loops and voids were investigated. The changes in yield strength due to irradiation were estimated from Vickers hardness measurements and compared to calculations using a dispersed-barrier hardening model. The dose and temperature dependence of microstructure and hardness change for proton irradiation follows the same trend as that for neutron irradiation at comparable irradiation conditions. Commercial purity alloys of CP 304 SS and CP 316 SS were irradiated at 360°C to doses between 0.3 and 3.0 dpa. The irradiated microstructure consists of dislocation loops. No voids were detected at doses up to 3.0 dpa. Loop size distributions are in close agreement with that in the same alloys neutron-irradiated in a LWR core. The loop density also agrees with neutron irradiation data. The yield strength as a function of dose in proton irradiated commercial purity alloys is consistent with the neutron- data trend. A fast-reactor microstructure model was adapted for light water reactor (LWR) irradiation conditions (275°C, 7 × 10 -8 dpa/s) and then applied to proton irradiation under conditions (360°C, 7 × 10-6 dpa/s) relevant to LWRs. The original model was modified by including in-cascade interstitial clustering and the loss of interstitial clusters to sinks by cluster diffusion. It was demonstrated that loop nucleation for both LWR irradiation condition and proton irradiation are driven by in-cascade interstitial clustering. One important result from this modeling work is that the difference in displacement cascade between

  7. Hematological and TGF-beta variations after whole-body proton irradiation

    NASA Technical Reports Server (NTRS)

    Kajioka, E. H.; Andres, M. L.; Mao, X. W.; Moyers, M. F.; Nelson, G. A.; Gridley, D. S.

    2000-01-01

    The acute effects of proton whole-body irradiation on five bone-marrow-derived cell types and transforming growth factor-beta 1 (TGF-beta 1) were examined and compared to the effects of photons (60Co). C57BL/6 mice were exposed to 3 Gy (0.4 Gy/min) protons at spread-out Bragg peak (SOBP), protons at entry (E), or 60Co and euthanized on days 0.5-17 thereafter. 60Co-irradiated animals had decreased erythrocytes, hemoglobin and hematocrit at 12 hours post-exposure; depression was not noted in proton (SOBP or E)-irradiated groups until day 4. Significantly decreased leukocyte counts were observed at this same time in all irradiated groups, with lymphocyte loss being greater than that of monocytes, and the depression was generally maintained. In contrast, the levels of neutrophils and thrombocytes fluctuated, especially during the first week; significant differences were noted among irradiated groups in neutrophil levels. Plasma TGF-beta 1 was elevated on day 7 in the 60Co, but not proton, irradiated mice. Collectively, the data show that dramatic and persistent changes occurred in all irradiated groups. However, few differences in assay results were seen between animals exposed to protons (SOBP or E) or photons, as well as between the groups irradiated with either of the two regions of the proton Bragg curve.

  8. Trapping of noble gases in proton-irradiated silicate smokes

    NASA Astrophysics Data System (ADS)

    Nichols, R. H., Jr.; Nuth, J. A., III; Hohenberg, C. M.; Olinger, C. T.; Moore, M. H.

    1992-12-01

    We have measured Ne, Ar, Kr, and Xe in Si2O3 'smokes' that were condensed on Al substrates, vapor-deposited with various mixtures of CH4, NH3, H2O3 and noble gases at 10 K and subsequently irradiated with 1 MeV protons to simulate conditions during grain mantle formation in interstellar clouds. Neither Ne nor Ar is retained by the samples upon warming to room temperature, but Xe is very efficiently trapped and retained. Kr is somewhat less effectively retained, typically depleted by factors of about 10-20 relative to Xe. Isotopic fractionation favoring the heavy isotopes of Xe and Kr of about 5-10-percent/amu is observed. Correlations between the specific chemistry of the vapor deposition and heavy noble gas retention are most likely the result of competition by the various species for irradiation-produced trapping sites. The concentration of Xe retained by some of these smokes exceeds that observed in phase Q of meteorites and, like phase Q, they do not seem to be carriers of the light noble gases.

  9. Trapping of noble gases in proton-irradiated silicate smokes

    NASA Technical Reports Server (NTRS)

    Nichols, R. H., Jr.; Nuth, J. A., III; Hohenberg, C. M.; Olinger, C. T.; Moore, M. H.

    1992-01-01

    We have measured Ne, Ar, Kr, and Xe in Si2O3 'smokes' that were condensed on Al substrates, vapor-deposited with various mixtures of CH4, NH3, H2O3 and noble gases at 10 K and subsequently irradiated with 1 MeV protons to simulate conditions during grain mantle formation in interstellar clouds. Neither Ne nor Ar is retained by the samples upon warming to room temperature, but Xe is very efficiently trapped and retained. Kr is somewhat less effectively retained, typically depleted by factors of about 10-20 relative to Xe. Isotopic fractionation favoring the heavy isotopes of Xe and Kr of about 5-10-percent/amu is observed. Correlations between the specific chemistry of the vapor deposition and heavy noble gas retention are most likely the result of competition by the various species for irradiation-produced trapping sites. The concentration of Xe retained by some of these smokes exceeds that observed in phase Q of meteorites and, like phase Q, they do not seem to be carriers of the light noble gases.

  10. Control of Refractive Index of Fluorinated Polyimide by Proton Beam Irradiation

    NASA Astrophysics Data System (ADS)

    Arai, Yukitaka; Ohki, Yoshimichi; Saito, Keisuke; Nishikawa, Hiroyuki

    2013-01-01

    To clarify the feasibility of controlling the refractive index of a polymer by proton beam irradiation, we irradiated 1.0 MeV protons to a fluorinated polyimide film. Before and after the proton irradiation at a fluence between 1×1014 and 7×1016 cm-2, the film surface was scanned by a profilometer. It was found that the depth of a dent, which increases with fluence, was induced by the irradiation. The refractive index of the ion-irradiated region was calculated using the Lorentz-Lorenz equation, substituting the depth of the dent and the projected range of the protons. When the fluorinated polyimide was irradiated at a fluence of 7×1016 cm-2, the refractive index increased by about 3.3%, which agrees with the increment in refractive index measured by spectroscopic ellipsometry. The increment in refractive index (0.21%) induced by the irradiation of protons at the fluence of 1×1015 cm-2 is comparable to the value (0.35%) observed when protons were irradiated to SiO2 glass at a similar fluence. Therefore, it is reasonable to assume that the ion irradiation to a polymer can be a good method for fabricating a high-performance polymer-based optical waveguide.

  11. Positron probing of phosphorus-vacancy complexes in silicon irradiated with 15 MeV protons

    NASA Astrophysics Data System (ADS)

    Arutyunov, N.; Emtsev, V.; Krause-Rehberg, R.; Elsayed, M.; Kessler, C.; Kozlovski, V.; Oganesyan, G.

    2015-06-01

    Defects in phosphorus-doped silicon samples of floating-zone material, n-FZ-Si(P), produced under irradiation with 15 MeV protons at room temperature are studied by positron annihilation lifetime spectroscopy over the temperature range of ∼ 30 K - 300 K and by low- temperature Hall effect measurements. After annealing of E-centersand divacancies, we detected for the first time high concentrations of positron traps which had not been observed earlier. These defects are isochronally annealed over the temperature interval of ∼ 320 °C - 700 °C they manifest themselves as electrically neutral deep donor centersin the material of n-type. A long-lived component of the positron lifetime, τ2(I2 < 60%) ∼ 280 ps, attributed to these centers, suggests a relaxed configuration involving two vacancies. The enthalpy and entropy of annealing of these centersare Ea ∼ 1.05(0.21) eV and ΔSm ≈ 3.1(0.6)kB, respectively. It is argued that the microstructure of the defect consists of two vacancies, VV, and one atom of phosphorus, P. The split configuration of the VPV complex is shortly discussed.

  12. Low Temperature Physics

    NASA Astrophysics Data System (ADS)

    Ruhemann, M.; Ruhemann, B.

    2014-05-01

    Part I. Phase Equilibrium: 1. Early methods of gas liquefaction; 2. Industrial air liquefaction; 3. The production of low temperatures; 4. The measurement of low temperatures; 5. Rectification in theory and practice; 6. Solid liquid equilibrium; Part II. The Solid State: 1. The crystal lattice; 2. The thermal energy of crystals; 3. Nernst's third law; Part III. Orbit and Spin: 1. Internal degrees of freedom; 2. Paramagnetism; 3. Magnetic cooling; Part IV. The 'Free' Electron: 1. Conductivity at low temperatures; 2. Supra-conductivity; Note added in proof; Bibliography; Addenda.

  13. Irradiation-induced effects of proton irradiation on zirconium carbides with different stoichiometries

    SciTech Connect

    Y. Huang; B.R. Maier; T.R. Allen

    2014-10-01

    Zirconium carbide (ZrC) is being considered for utilization in deep burn TRISO fuel particles for hightemperature, gas-cooled reactors. Zirconium carbide has a cubic B1 type crystal structure along with a very high melting point (3420 ?C), exceptional hardness and good thermal and electrical conductivities. Understanding the ZrC irradiation response is crucial for establishing ZrC as an alternative component in TRISO fuel. Until now, very few studies on irradiation effects on ZrC have been released and fundamental aspects of defect evolution and kinetics are not well understood although some atomistic simulations and phenomenological studies have been performed. This work was carried out to understand the damage evolution in float-zone refined ZrC with different stoichiometries. Proton irradiations at 800 ?C up to doses of 3 dpa were performed on ZrCx (where x ranges from 0.9 to 1.2) to investigate the damage evolution. The irradiation-induced defects, such as density of dislocation loops, at different stoichiometries and doses which were characterized by transmission electron microscopy (TEM) is presented and discussed.

  14. Silicon/HfO{sub 2} interface: Effects of proton irradiation

    SciTech Connect

    Maurya, Savita; Radhakrishna, M.

    2015-06-24

    Substrate oxide interfaces are of paramount importance in deciding the quality of the semiconductor devices. In this work we have studied how 200 keV proton irradiation affects the interface of a 13 nm thick, atomic layer deposited hafnium dioxide on silicon substrate. Pre- and post-irradiation electrical measurements are used to quantify the effect of proton irradiation for varying electrode geometries. Proton irradiation introduces positive charge in the oxide and at the interface of Si/HfO{sub 2} interface. The gate current is not very much affected under positive injection since the induced positive charge is compensated by the injected electrons. Current voltage characteristics under negative bias get affected by the proton irradiation.

  15. Layer-structured LiNi0.8Co0.2O2: A new triple (H+/O2-/e-) conducting cathode for low temperature proton conducting solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Fan, Liangdong; Su, Pei-Chen

    2016-02-01

    Solid oxide fuel cells with proton conducting electrolytes (H-SOFCs) show great potential for more efficient energy conversion over their oxygen ionic conducting counterparts at temperatures below 650 °C, providing a comparably high performance cathode material can be available. A brief review of current development of cathode materials shows that materials with triple (oxygen ionic, protonic, and electronic) conducting properties are most promising for H-SOFCs. In this work, a triple-conducting LiNi0.8Co0.2O2 (LNCO) with layered structure, allowing simultaneous conduction of intrinsic oxygen ion and electron as well as the extrinsic proton, is proposed as a cathode material for H-SOFC. The electrochemical impedance spectroscopy analysis of LNCO shows the good oxygen reduction reaction (ORR) activity with a considerably low activation energy of 0.88 eV, and an evident water uptake capability those facilitate the cathode reaction process. Fuel cells using LNCO cathode on a BaZr0.1Ce0.7Y0.2O3 proton-conducting electrolyte render a peak power density of 410 mW cm-2 at 650 °C under H2/air condition, which is higher than most of the typical cathode materials reported with similar cell configurations. This work also demonstrated a new series of simple and low cost cathode materials simultaneously possessing interesting triple-conduction and good ORR activities for low temperature H-SOFCs.

  16. {sup 55}Co separation from proton irradiated metallic nickel

    SciTech Connect

    Valdovinos, H. F. Graves, S. Barnhart, T. Nickles, R. J.

    2014-11-07

    {sup 55}Co with > 97% radionuclidic purity 24 hours after end of bombardment (EoB) was produced from the {sup 58}Ni(p,α) reaction using proton irradiations of 16 MeV on natural nickel. Two-hour irradiations with 25 μA on a 254 μm thick nickel foil generate 0.18 ± 0.01 GBq (n = 3) 24 hours after EoB. The separation of cobalt from the target material and other metallic contaminants present at trace levels is accomplished in HCl medium by two rounds of anion exchange chromatography (AG1-X8) using an automated module driven by a peristaltic pump. 80 ± 5 % (n = 3) of the activity generated at EoB is ready for labeling in 0.1 M HCl one hour after the start of separation. Using 99.999% pure Ni, the reactivity (decay corrected to EoB) with the bifunctional chelator (BFC) DOTA was 8.5 GBq/μmol; enough for radiolabeling BFC conjugated biomolecules at a nmol scale with > 90% yield. Using 99.9% pure Ni the reactivity with DOTA and NOTA was 0.19 +/− 0.09 GBq/μmol and 2.9 +/− 1.7 GBq/μmol (n = 2), respectively. Both cobalt complexes showed 100% in vitro stability in PBS and mouse serum over 41 hours at room temperature. MicroPET images of a miniature Derenzo phantom show excellent resolution where rods of 1.5 mm were separated by two times their diameter.

  17. 55Co separation from proton irradiated metallic nickel

    NASA Astrophysics Data System (ADS)

    Valdovinos, H. F.; Graves, S.; Barnhart, T.; Nickles, R. J.

    2014-11-01

    55Co with > 97% radionuclidic purity 24 hours after end of bombardment (EoB) was produced from the 58Ni ( p ,α) reaction using proton irradiations of 16 MeV on natural nickel. Two-hour irradiations with 25 μA on a 254 μm thick nickel foil generate 0.18 ± 0.01 GBq (n = 3) 24 hours after EoB. The separation of cobalt from the target material and other metallic contaminants present at trace levels is accomplished in HCl medium by two rounds of anion exchange chromatography (AG1-X8) using an automated module driven by a peristaltic pump. 80 ± 5 % (n = 3) of the activity generated at EoB is ready for labeling in 0.1 M HCl one hour after the start of separation. Using 99.999% pure Ni, the reactivity (decay corrected to EoB) with the bifunctional chelator (BFC) DOTA was 8.5 GBq/μmol; enough for radiolabeling BFC conjugated biomolecules at a nmol scale with > 90% yield. Using 99.9% pure Ni the reactivity with DOTA and NOTA was 0.19 +/- 0.09 GBq/μmol and 2.9 +/- 1.7 GBq/μmol (n = 2), respectively. Both cobalt complexes showed 100% in vitro stability in PBS and mouse serum over 41 hours at room temperature. MicroPET images of a miniature Derenzo phantom show excellent resolution where rods of 1.5 mm were separated by two times their diameter.

  18. Luminescence imaging of water during proton-beam irradiation for range estimation

    SciTech Connect

    Yamamoto, Seiichi Okumura, Satoshi; Komori, Masataka; Toshito, Toshiyuki

    2015-11-15

    Purpose: Proton therapy has the ability to selectively deliver a dose to the target tumor, so the dose distribution should be accurately measured by a precise and efficient method. The authors found that luminescence was emitted from water during proton irradiation and conjectured that this phenomenon could be used for estimating the dose distribution. Methods: To achieve more accurate dose distribution, the authors set water phantoms on a table with a spot scanning proton therapy system and measured the luminescence images of these phantoms with a high-sensitivity, cooled charge coupled device camera during proton-beam irradiation. The authors imaged the phantoms of pure water, fluorescein solution, and an acrylic block. Results: The luminescence images of water phantoms taken during proton-beam irradiation showed clear Bragg peaks, and the measured proton ranges from the images were almost the same as those obtained with an ionization chamber. Furthermore, the image of the pure-water phantom showed almost the same distribution as the tap-water phantom, indicating that the luminescence image was not related to impurities in the water. The luminescence image of the fluorescein solution had ∼3 times higher intensity than water, with the same proton range as that of water. The luminescence image of the acrylic phantom had a 14.5% shorter proton range than that of water; the proton range in the acrylic phantom generally matched the calculated value. The luminescence images of the tap-water phantom during proton irradiation could be obtained in less than 2 s. Conclusions: Luminescence imaging during proton-beam irradiation is promising as an effective method for range estimation in proton therapy.

  19. Improved normal tissue protection by proton and X-ray microchannels compared to homogeneous field irradiation.

    PubMed

    Girst, S; Marx, C; Bräuer-Krisch, E; Bravin, A; Bartzsch, S; Oelfke, U; Greubel, C; Reindl, J; Siebenwirth, C; Zlobinskaya, O; Multhoff, G; Dollinger, G; Schmid, T E; Wilkens, J J

    2015-09-01

    The risk of developing normal tissue injuries often limits the radiation dose that can be applied to the tumour in radiation therapy. Microbeam Radiation Therapy (MRT), a spatially fractionated photon radiotherapy is currently tested at the European Synchrotron Radiation Facility (ESRF) to improve normal tissue protection. MRT utilizes an array of microscopically thin and nearly parallel X-ray beams that are generated by a synchrotron. At the ion microprobe SNAKE in Munich focused proton microbeams ("proton microchannels") are studied to improve normal tissue protection. Here, we comparatively investigate microbeam/microchannel irradiations with sub-millimetre X-ray versus proton beams to minimize the risk of normal tissue damage in a human skin model, in vitro. Skin tissues were irradiated with a mean dose of 2 Gy over the irradiated area either with parallel synchrotron-generated X-ray beams at the ESRF or with 20 MeV protons at SNAKE using four different irradiation modes: homogeneous field, parallel lines and microchannel applications using two different channel sizes. Normal tissue viability as determined in an MTT test was significantly higher after proton or X-ray microchannel irradiation compared to a homogeneous field irradiation. In line with these findings genetic damage, as determined by the measurement of micronuclei in keratinocytes, was significantly reduced after proton or X-ray microchannel compared to a homogeneous field irradiation. Our data show that skin irradiation using either X-ray or proton microchannels maintain a higher cell viability and DNA integrity compared to a homogeneous irradiation, and thus might improve normal tissue protection after radiation therapy.

  20. Low temperature fluid blender

    NASA Technical Reports Server (NTRS)

    Repas, G. A.

    1971-01-01

    Blender supplies hydrogen at temperatures from 289 deg K to 367 deg K. Hydrogen temperature is controlled by using blender to combine flow from liquid hydrogen tank /276 deg K/ and gaseous hydrogen cylinder /550 deg K/. Blenders are applicable where flow of controlled low-temperature fluid is desired.

  1. Attaining Low Temperatures

    ERIC Educational Resources Information Center

    Wheatley, John D.; Van Till, Howard J.

    1970-01-01

    Discusses the definition of temperature and the concept of order in non-mathematical terms. Describes the cooling techniques necessary in low temperature physics research, including magnetic cooling, the use of the Pomeranchuk Effect, and dilution refrigeration. Outlines the types of phenomena observed in matter within various temperature ranges…

  2. Dynamics of modification of Ni/n-GaN Schottky barrier diodes irradiated at low temperature by 200 MeV Ag{sup 14+} ions

    SciTech Connect

    Kumar, Ashish; Kumar, Tanuj; Kanjilal, D.; Hähnel, A.; Singh, R.

    2014-01-20

    Ni/GaN Schottky barrier diodes were irradiated with 200 MeV Ag ions up to fluence of 1 × 10{sup 11} ions/cm{sup 2} at the substrate temperature of 80 K. Post-irradiation current-voltage measurements showed that the ideality factor, n increased and the reverse leakage current, I{sub R} decreased with increase in fluence. But Schottky barrier height, ϕ{sub b} increased only marginally with increase in ion fluence. In situ resistivity measurements showed orders of magnitude increase in resistivity of GaN epitaxial film with irradiation fluence. Cross-sectional transmission electron microscopy images revealed the presence of defect clusters in bulk GaN after irradiation.

  3. Investigation of microstructure and mechanical properties of proton irradiated Zircaloy 2

    NASA Astrophysics Data System (ADS)

    Sarkar, Apu; Kumar, Ajay; Mukherjee, S.; Sharma, S. K.; Dutta, D.; Pujari, P. K.; Agarwal, A.; Gupta, S. K.; Singh, P.; Chakravartty, J. K.

    2016-10-01

    Samples of Zircaloy 2 have been irradiated with 4 MeV protons to two different doses. Microstructures of the unirradiated and irradiated samples have been characterized by Electron Back Scatter Diffraction (EBSD), X-ray diffraction line profile analysis (XRDLPA), Positron Annihilation Lifetime Spectroscopy (PALS) and Coincident Doppler Broadening (CDB) Spectroscopy. Tensile tests and micro hardness measurements have been carried out at room temperature to assess the changes in mechanical properties of Zircaloy 2 due to proton irradiation. The correlation of dislocation density, grain size and yield stress of the irradiated samples indicated that an increase in dislocation density due to irradiation is responsible for the change in mechanical behavior of irradiated Zircaloy.

  4. High total dose proton irradiation effects on silicon NPN rf power transistors

    NASA Astrophysics Data System (ADS)

    Bharathi, M. N.; Praveen, K. C.; Pushpa, N.; Prakash, A. P. Gnana

    2014-04-01

    The effects of 3 MeV proton irradiation on the I-V characteristics of NPN rf power transistors were studied in the dose range of 100 Krad to 100 Mrad. The different electrical characteristics like Gummel, current gain and output characteristics were systematically studied before and after irradiation. The recovery in the I-V characteristics of irradiated NPN BJTs were studied by isochronal and isothermal annealing methods.

  5. Radiograaff, a proton irradiation facility for radiobiological studies at a 4 MV Van de Graaff accelerator

    NASA Astrophysics Data System (ADS)

    Constanzo, J.; Fallavier, M.; Alphonse, G.; Bernard, C.; Battiston-Montagne, P.; Rodriguez-Lafrasse, C.; Dauvergne, D.; Beuve, M.

    2014-09-01

    A horizontal beam facility for radiobiological experiments with low-energy protons has been set up at the 4 MV Van de Graaff accelerator of the Institut de Physique Nucléaire de Lyon. A homogeneous irradiation field with a suitable proton flux is obtained by means of two collimators and two Au-scattering foils. A monitoring chamber contains a movable Faraday cup, a movable quartz beam viewer for controlling the intensity and the position of the initial incident beam and four scintillating fibers for beam monitoring during the irradiation of the cell samples. The beam line is ended by a thin aluminized Mylar window (12 μm thick) for the beam extraction in air. The set-up was simulated by the GATE v6.1 Monte-Carlo platform. The measurement of the proton energy distribution, the evaluation of the fluence-homogeneity over the sample and the calibration of the monitoring system were performed using a silicon PIPS detector, placed in air in the same position as the biological samples to be irradiated. The irradiation proton fluence was found to be homogeneous to within ±2% over a circular field of 20 mm diameter. As preliminary biological experiment, two Human Head and Neck Squamous Carcinoma Cell lines (with different radiosensitivities) were irradiated with 2.9 MeV protons. The measured survival curves are compared to those obtained after X-ray irradiation, giving a Relative Biological Efficiency between 1.3 and 1.4.

  6. Proton irradiation suppresses angiogenic genes and impairs cell invasion and tumor growth.

    PubMed

    Girdhani, Swati; Lamont, Clare; Hahnfeldt, Philip; Abdollahi, Amir; Hlatky, Lynn

    2012-07-01

    The energy deposition characteristics of proton radiation have attracted considerable attention in light of its implications for carcinogenesis risk in space travel, as well for application to cancer treatment. In space, it is the principle component of the galactic cosmic radiation to which astronauts will be exposed. For treatment, an increasing number of proton facilities are being established to exploit the physical advantages of this radiation type. However, the possibility that there may also be biologically based advantages to proton exposure has not been considered in either context. We demonstrate here that high-energy proton irradiation can inhibit expression of major pro-angiogenic factors and multiple angiogenesis-associated processes, including invasion and endothelial cell proliferation, which is prominent in cancer progression. Dose-dependent suppression of angiogenic signaling was demonstrated for both cancer and nontransformed cells. Pan-genomic microarray analysis and RT-PCR revealed that post-irradiation (0.5, 1.0 and 2.0 Gy), critical pro-angiogenic signaling factors including: vascular endothelial growth factor (VEGF), interleukin 6 and 8 (IL-6, IL-8) and hypoxia-inducible factor-1 alpha (HIF-1A), were significantly downregulated. Co-culture studies demonstrated that endothelial cell proliferation and invasion were inhibited by culturing with irradiated cancer or fibroblast cells, which suggests that proton irradiation may, in addition to direct action, contribute to angiogenesis suppression through modulation of paracrine signalings from targeted cells. Addition of recombinant IL-8 or VEGF partially restored these functions in vitro, while in vivo, an attenuated tumor growth rate was demonstrated for proton-irradiated human lung cancer cells. Taken together, these findings provide novel pre-clinical evidence that proton irradiation may, in addition to its physical targeting advantages, have important biological ramifications that should be a

  7. Proton irradiation suppresses angiogenic genes and impairs cell invasion and tumor growth.

    PubMed

    Girdhani, Swati; Lamont, Clare; Hahnfeldt, Philip; Abdollahi, Amir; Hlatky, Lynn

    2012-07-01

    The energy deposition characteristics of proton radiation have attracted considerable attention in light of its implications for carcinogenesis risk in space travel, as well for application to cancer treatment. In space, it is the principle component of the galactic cosmic radiation to which astronauts will be exposed. For treatment, an increasing number of proton facilities are being established to exploit the physical advantages of this radiation type. However, the possibility that there may also be biologically based advantages to proton exposure has not been considered in either context. We demonstrate here that high-energy proton irradiation can inhibit expression of major pro-angiogenic factors and multiple angiogenesis-associated processes, including invasion and endothelial cell proliferation, which is prominent in cancer progression. Dose-dependent suppression of angiogenic signaling was demonstrated for both cancer and nontransformed cells. Pan-genomic microarray analysis and RT-PCR revealed that post-irradiation (0.5, 1.0 and 2.0 Gy), critical pro-angiogenic signaling factors including: vascular endothelial growth factor (VEGF), interleukin 6 and 8 (IL-6, IL-8) and hypoxia-inducible factor-1 alpha (HIF-1A), were significantly downregulated. Co-culture studies demonstrated that endothelial cell proliferation and invasion were inhibited by culturing with irradiated cancer or fibroblast cells, which suggests that proton irradiation may, in addition to direct action, contribute to angiogenesis suppression through modulation of paracrine signalings from targeted cells. Addition of recombinant IL-8 or VEGF partially restored these functions in vitro, while in vivo, an attenuated tumor growth rate was demonstrated for proton-irradiated human lung cancer cells. Taken together, these findings provide novel pre-clinical evidence that proton irradiation may, in addition to its physical targeting advantages, have important biological ramifications that should be a

  8. A local proton irradiation model for isotopic anomalies in the solar system

    NASA Technical Reports Server (NTRS)

    Lee, T.

    1978-01-01

    An attempt is made to explain the O-16 and Al-26 anomalies observed in solar-system bodies in the framework of a local irradiation model wherein a small amount of solar system matter of normal isotopic composition was irradiated by energetic protons from the primeval sun. Several isotopic constraints are summarized with which the model should be consistent, and a proton energy distribution and fluence and a target elemental composition are chosen such that the extraordinary component produced by irradiation satisfies the constraints. Detailed attention is given to the relevant oxygen reactions, Al-26 production, and effects of proton irradiation on isotopes of Mg, Ca, and Ba. A scenario is outlined which satisfies all the constraints. Consequences of the model are discussed with respect to the isotopic anomalies observed in Allende inclusions.

  9. Whole-Body Proton Irradiation Causes Long-Term Damage to Hematopoietic Stem Cells in Mice

    PubMed Central

    Chang, Jianhui; Feng, Wei; Wang, Yingying; Luo, Yi; Allen, Antiño R.; Koturbash, Igor; Turner, Jennifer; Stewart, Blair; Raber, Jacob; Hauer-Jensen, Martin; Zhou, Daohong; Shao, Lijian

    2016-01-01

    Space flight poses certain health risks to astronauts, including exposure to space radiation, with protons accounting for more than 80% of deep-space radiation. Proton radiation is also now being used with increasing frequency in the clinical setting to treat cancer. For these reasons, there is an urgent need to better understand the biological effects of proton radiation on the body. Such improved understanding could also lead to more accurate assessment of the potential health risks of proton radiation, as well as the development of improved strategies to prevent and mitigate its adverse effects. Previous studies have shown that exposure to low doses of protons is detrimental to mature leukocyte populations in peripheral blood, however, the underlying mechanisms are not known. Some of these detriments may be attributable to damage to hematopoietic stem cells (HSCs) that have the ability to self-renew, proliferate and differentiate into different lineages of blood cells through hematopoietic progenitor cells (HPCs). The goal of this study was to investigate the long-term effects of low-dose proton irradiation on HSCs. We exposed C57BL/6J mice to 1.0 Gy whole-body proton irradiation (150 MeV) and then studied the effects of proton radiation on HSCs and HPCs in the bone marrow (BM) 22 weeks after the exposure. The results showed that mice exposed to 1.0 Gy whole-body proton irradiation had a significant and persistent reduction of BM HSCs compared to unirradiated controls. In contrast, no significant changes were observed in BM HPCs after proton irradiation. Furthermore, irradiated HSCs and their progeny exhibited a significant impairment in clonogenic function, as revealed by the cobblestone area-forming cell (CAFC) and colony-forming cell assays, respectively. These long-term effects of proton irradiation on HSCs may be attributable to the induction of chronic oxidative stress in HSCs, because HSCs from irradiated mice exhibited a significant increase in NADPH

  10. Whole-body proton irradiation causes long-term damage to hematopoietic stem cells in mice.

    PubMed

    Chang, Jianhui; Feng, Wei; Wang, Yingying; Luo, Yi; Allen, Antiño R; Koturbash, Igor; Turner, Jennifer; Stewart, Blair; Raber, Jacob; Hauer-Jensen, Martin; Zhou, Daohong; Shao, Lijian

    2015-02-01

    Space flight poses certain health risks to astronauts, including exposure to space radiation, with protons accounting for more than 80% of deep-space radiation. Proton radiation is also now being used with increasing frequency in the clinical setting to treat cancer. For these reasons, there is an urgent need to better understand the biological effects of proton radiation on the body. Such improved understanding could also lead to more accurate assessment of the potential health risks of proton radiation, as well as the development of improved strategies to prevent and mitigate its adverse effects. Previous studies have shown that exposure to low doses of protons is detrimental to mature leukocyte populations in peripheral blood, however, the underlying mechanisms are not known. Some of these detriments may be attributable to damage to hematopoietic stem cells (HSCs) that have the ability to self-renew, proliferate and differentiate into different lineages of blood cells through hematopoietic progenitor cells (HPCs). The goal of this study was to investigate the long-term effects of low-dose proton irradiation on HSCs. We exposed C57BL/6J mice to 1.0 Gy whole-body proton irradiation (150 MeV) and then studied the effects of proton radiation on HSCs and HPCs in the bone marrow (BM) 22 weeks after the exposure. The results showed that mice exposed to 1.0 Gy whole-body proton irradiation had a significant and persistent reduction of BM HSCs compared to unirradiated controls. In contrast, no significant changes were observed in BM HPCs after proton irradiation. Furthermore, irradiated HSCs and their progeny exhibited a significant impairment in clonogenic function, as revealed by the cobblestone area-forming cell (CAFC) and colony-forming cell assays, respectively. These long-term effects of proton irradiation on HSCs may be attributable to the induction of chronic oxidative stress in HSCs, because HSCs from irradiated mice exhibited a significant increase in NADPH

  11. Whole-body proton irradiation causes long-term damage to hematopoietic stem cells in mice.

    PubMed

    Chang, Jianhui; Feng, Wei; Wang, Yingying; Luo, Yi; Allen, Antiño R; Koturbash, Igor; Turner, Jennifer; Stewart, Blair; Raber, Jacob; Hauer-Jensen, Martin; Zhou, Daohong; Shao, Lijian

    2015-02-01

    Space flight poses certain health risks to astronauts, including exposure to space radiation, with protons accounting for more than 80% of deep-space radiation. Proton radiation is also now being used with increasing frequency in the clinical setting to treat cancer. For these reasons, there is an urgent need to better understand the biological effects of proton radiation on the body. Such improved understanding could also lead to more accurate assessment of the potential health risks of proton radiation, as well as the development of improved strategies to prevent and mitigate its adverse effects. Previous studies have shown that exposure to low doses of protons is detrimental to mature leukocyte populations in peripheral blood, however, the underlying mechanisms are not known. Some of these detriments may be attributable to damage to hematopoietic stem cells (HSCs) that have the ability to self-renew, proliferate and differentiate into different lineages of blood cells through hematopoietic progenitor cells (HPCs). The goal of this study was to investigate the long-term effects of low-dose proton irradiation on HSCs. We exposed C57BL/6J mice to 1.0 Gy whole-body proton irradiation (150 MeV) and then studied the effects of proton radiation on HSCs and HPCs in the bone marrow (BM) 22 weeks after the exposure. The results showed that mice exposed to 1.0 Gy whole-body proton irradiation had a significant and persistent reduction of BM HSCs compared to unirradiated controls. In contrast, no significant changes were observed in BM HPCs after proton irradiation. Furthermore, irradiated HSCs and their progeny exhibited a significant impairment in clonogenic function, as revealed by the cobblestone area-forming cell (CAFC) and colony-forming cell assays, respectively. These long-term effects of proton irradiation on HSCs may be attributable to the induction of chronic oxidative stress in HSCs, because HSCs from irradiated mice exhibited a significant increase in NADPH

  12. Production of proton beams with narrow-band energy spectra from laser-irradiated ultrathin foils

    SciTech Connect

    Robinson, A. P. L; Gibbon, P.

    2007-01-15

    Three-dimensional gridless particle simulations of proton acceleration via irradiation of a very thin foil by a short-pulse, high-intensity laser have been performed to evaluate recently proposed microstructured target configurations. It is found that a pure proton microdot target does not by itself result in a quasimonoenergetic proton beam. Such a beam can only be produced with a very lightly doped target, in qualitative agreement with one-dimensional theory. The simulations suggest that beam quality in current experiments could be dramatically improved by choosing microdot compositions with a 5-10 times lower proton fraction.

  13. The effects of 800 MeV proton irradiation on the corrosion of tungsten, tantalum, stainless steel, and gold

    SciTech Connect

    Lillard, R.S.; Butt, D.P.; Kanner, G.; Daemen, L.

    1997-12-01

    Real time electrochemical data were acquired for tungsten, tantalum, stainless steel 304L, and gold targets during proton irradiation at the LANSCE Weapons Neutron Research Facility. The goal of this research was to establish a better understanding of the corrosion properties of materials as a function of proton irradiation and gain insight into the mechanism of the observed phenomena. The following electrochemical observations were made during proton irradiation of W, Ta, SS304, and Au: (1) the open circuit potential of all materials increased with increasing proton fluence; (2) the corrosion rate (at the OCP) of W and SS304 increased with increasing proton fluence; (3) the passive dissolution rate for SS304 and Ta decreased with increasing proton fluence; (4) the anodic dissolution rate for W increased with increasing proton fluence; (5) the pitting potential for SS304 increased with proton fluence, which is an indication that the material is less susceptible to pitting attack during irradiation.

  14. Random telegraph signals from proton-irradiated CCDS

    SciTech Connect

    Hopkins, I.H. ); Hopkinson, G.R. )

    1993-12-01

    Temporal fluctuations have recently been discovered in the dark current of proton-displacement-damaged CCDs. These fluctuations take the form of random telegraph signals with well defined amplitudes and time constants (for tile high and low dark current states). Temperature and annealing behavior have been studied, as has the dependence on proton fluence. A bistable defect mechanism is proposed.

  15. Pyrolytic carbon free-radical evolution and irradiation damage of polyimide under low-energy proton irradiation

    SciTech Connect

    Sun Chengyue; Wu Yiyong; Xiao Jingdong; Li Ruifeng; Yang Dezhuang; He Shiyu

    2011-12-15

    Ionization and displacement effects are basic phenomena in damage processes of materials under space-particle irradiation. In this paper, the damage behaviors were investigated on the polyimide under proton irradiation using electron paramagnetic resonance (EPR) spectra analysis and optical absorbance valuation. The results indicate that the proton irradiation induces the formation of pyrolytic carbon free-radical with a g value of 2.0025, and the population of free radicals increases with the irradiation fluence. The most important finding is that the irradiation-induced free-radical population increases linearly with the displacement damage dose, as does the optical degradation, whereas the ionization effect alone, during the irradiation, cannot induce the formation of pyrolytic carbon free radical. Furthermore, during the post storage, after irradiation, the free-radical population decreases following a sum of an exponential and a linear mode with the storage time. It is interesting that, during the post storage, the recovery of the degraded optical absorbance of the polyimide follows a similar mode to that of free radicals, and the characteristic time constant changes with the wavelength of the optical spectra.

  16. Effect of UV-C irradiation and low temperature storage on bioactive compounds, antioxidant enzymes and radical scavenging activity of papaya fruit.

    PubMed

    Rivera-Pastrana, Dulce M; Gardea, Alfonso A; Yahia, Elhadi M; Martínez-Téllez, Miguel A; González-Aguilar, Gustavo A

    2014-12-01

    Mature green 'Maradol' papaya fruits were exposed to ultraviolet (UV)-C irradiation (1.48 kJ·m(-2)) and stored at 5 or 14 °C. Changes in total phenols, total flavonoids, enzymatic activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), as well as the scavenging activity against 2,2-diphenyl-1picrylhydrazyl (DPPH) and 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radicals were investigated in peel and flesh tissues at 0, 5, 10 and 15 days of storage. UV-C irradiation increased significantly (P < 0.05) the flavonoid content (2.5 and 26 %) and ABTS radical scavenging activity (5.7 and 6 %) in flesh and peel at 14 °C respectively; and CAT activity (16.7 %) in flesh at 5 °C. Flavonoid contents, CAT and SOD activities were positively affected under low storage temperature (5 °C). DPPH and ABTS radical scavenging activities increased in both control and UV-C treated papaya peel during storage at 5 °C. UV-C irradiation effect on radical scavenging of papaya peel could be attributed to increased flavonoid content. Papaya antioxidant system was activated by UV-C and cold storage by increasing phenolic content and antioxidant enzymatic activities as a defense response against oxidative-stress. PMID:25477649

  17. Low temperature materials

    NASA Astrophysics Data System (ADS)

    Ballingall, J. M.; Ho, P.; Mazurowski, J.; Lester, L.; Hwang, K. C.

    1994-03-01

    In(x)Ga(l-x)As (x=025-0.35) grown at low temperature on GaAs by molecular beam epitaxy is characterized by Hall effect, transmission electron microscopy, and ultrafast optical testing. As with low temperature (LT) GaAs, the resistivity is generally higher after a brief anneal at 600 C. High-resolution transmission electron micrography shows all the as-grown epilayers grown directly on GaAs to be heavily dislocated due to the large lattice mismatch (2-3%). Annealed layers also show precipitate formation, in addition to the dislocations. Like LT GaAs, In(x)Ga(1-x)As lifetimes shorten as growth temperatures are reduced; and LT In(x)Ga(l-x)As lifetimes are generally shorter in as-grown samples than in annealed samples. The metal-semiconductor-metal photodetectors we fabricated on the material exhibit response times of 1-3 picoseconds, comparable to results reported on GaAs grown at low temperature, and the fastest ever reported in the wavelength range of 1.0-1.3 microns. To improve the crystalline quality and to distinguish detector speed and responsivity limitations due to dislocations versus defects induced by LT growth, we have grown 3 microns-thick graded layers of In(x)Al(l-x)As between the GaAs substrates and In(0.35)Ga(0.65)As films. The In(x)Al(l-x)As layers are heavily dislocated, with the dislocation density increasing with distance from the GaAs substrate, and abruptly terminating at or below the In(0.35)Ga(0.65)As layer.

  18. DNA double strand breaks and Hsp70 expression in proton irradiated living cells

    NASA Astrophysics Data System (ADS)

    Fiedler, Anja; Reinert, Tilo; Tanner, Judith; Butz, Tilman

    2007-07-01

    DNA double strand breaks (DSBs) in living cells can be directly provoked by ionising radiation. DSBs can be visualized by immunostaining the phosphorylated histone γH2AX. Our concern was to test the feasibility of γH2AX staining for a direct visualization of single proton hits. If single protons produce detectable foci, DNA DSBs could be used as "biological track detectors" for protons. Ionising radiation can also damage proteins indirectly by inducing free radicals. Heat shock proteins (Hsp) help to refold or even degrade the damaged proteins. The level of the most famous heat shock protein Hsp70 is increased by ionising radiation. We investigated the expression of γH2AX and Hsp70 after cross and line patterned irradiation with counted numbers of 2.25 MeV protons on primary human skin fibroblasts. The proton induced DSBs appear more delocalised than it was expected by the ion hit accuracy. Cooling the cells before the irradiation reduces the delocalisation of DNA DSBs, which is probably caused by the reduced diffusion of DNA damaging agents. Proton irradiation seems to provoke protein damages mainly in the cytoplasm indicated by cytoplasmic Hsp70 aggregates. On the contrary, in control heat shocked cells the Hsp70 was predominantly localized in the cell nucleus. However, the irradiated area could not be recognized, all cells on the Si 3N 4 window showed a homogenous Hsp70 expression pattern.

  19. High-energy proton irradiation of C57Bl6 mice under hindlimb unloading

    NASA Astrophysics Data System (ADS)

    Mendonca, Marc; Todd, Paul; Orschell, Christie; Chin-Sinex, Helen; Farr, Jonathan; Klein, Susan; Sokol, Paul

    2012-07-01

    Solar proton events (SPEs) pose substantial risk for crewmembers on deep space missions. It has been shown that low gravity and ionizing radiation both produce transient anemia and immunodeficiencies. We utilized the C57Bl/6 based hindlimb suspension model to investigate the consequences of hindlimb-unloading induced immune suppression on the sensitivity to whole body irradiation with modulated 208 MeV protons. Eight-week old C57Bl/6 female mice were conditioned by hindlimb-unloading. Serial CBC and hematocrit assays by HEMAVET were accumulated for the hindlimb-unloaded mice and parallel control animals subjected to identical conditions without unloading. One week of hindlimb-unloading resulted in a persistent, statistically significant 10% reduction in RBC count and a persistent, statistically significant 35% drop in lymphocyte count. This inhibition is consistent with published observations of low Earth orbit flown mice and with crewmember blood analyses. In our experiments the cell count suppression was sustained for the entire six-week period of observation and persisted for at least 7 days beyond the period of active hindlimb-unloading. C57Bl/6 mice were also irradiated with 208 MeV Spread Out Bragg Peak (SOBP) protons at the Midwest Proton Radiotherapy Institute at the Indiana University Cyclotron Facility. We found that at 8.5 Gy hindlimb-unloaded mice were significantly more radiation sensitive with 35 lethalities out of 51 mice versus 15 out of 45 control (non-suspended) mice within 30 days of receiving 8.5 Gy of SOBP protons (p =0.001). Both control and hindlimb-unloaded stocktickerCBC analyses of 8.5 Gy proton irradiated and control mice by HEMAVET demonstrated severe reductions in WBC counts (Lymphocytes and PMNs) by day 2 post-irradiation, followed a week to ten days later by reductions in platelets, and then reductions in RBCs about 2 weeks post-irradiation. Recovery of all blood components commenced by three weeks post-irradiation. CBC analyses of 8

  20. Anti-angiogenic activity in metastasis of human breast cancer cells irradiated by a proton beam

    NASA Astrophysics Data System (ADS)

    Lee, Kyu-Shik; Shin, Jin-Sun; Nam, Kyung-Soo; Shon, Yun-Hee

    2012-07-01

    Angiogenesis is an essential process of metastasis in human breast cancer. We investigated the effects of proton beam irradiation on angiogenic enzyme activities and their expressions in MCF-7 human breast cancer cells. The regulation of angiogenic regulating factors, of transforming growth factor- β (TGF- β) and of vesicular endothelial growth factor (VEGF) expression in breast cancer cells irradiated with a proton beam was studied. Aromatase activity and mRNA expression, which is correlated with metastasis, were significantly decreased by irradiation with a proton beam in a dose-dependent manner. TGF- β and VEGF transcriptions were also diminished by proton beam irradiation. In contrast, transcription of tissue inhibitors of matrix metalloproteinases (TIMPs), also known as biological inhibitors of matrix metalloproteinases (MMPs), was dose-dependently enhanced. Furthermore, an increase in the expression of TIMPs caused th MMP-9 activity to be diminished and the MMP-9 and the MMP-2 expressions to be decreased. These results suggest that inhibition of angiogenesis by proton beam irradiation in breast cancer cells is closely related to inhibitions of aromatase activity and transcription and to down-regulation of TGF- β and VEGF transcription.

  1. Magnetic properties of proton irradiated BiFeO{sub 3}

    SciTech Connect

    Han, Seungkyu; Jin Kim, Sam; Sung Kim, Chul

    2013-05-07

    The crystal structure and magnetic properties of BiFeO{sub 3} samples, proton-irradiated with 0, 10, and 20 pC/{mu}m{sup 2}, were investigated with x-ray diffraction (XRD), vibrating sample magnetometer, and Moessbauer spectroscopy measurements. From the Rietveld refinement analysis of the XRD patterns, the crystal structure of BiFeO{sub 3} is determined to be rhombohedral with the space group of R3c. We have observed the decrease in the lattice constant and oxygen occupancy with proton irradiation. The magnetization hysteresis (M-H) curves show the appearance of the weak ferromagnetic behavior in the proton irradiated BiFeO{sub 3} samples. The Moessbauer spectra of proton irradiated BiFeO{sub 3} samples at 295 K were analyzed with two-sextets (B{sub 1} and B{sub 2}) and doublet. From the isomer shift ({delta}) values, ionic states were determined to be Fe{sup 3+}. Compared to non-irradiated sample, having the antiferromagnetic area ratio (two-sextets) of 45.47, 54.53% the antiferromagnetic and paramagnetic area ratios (doublet) of 10 and 20 pC/{mu}m{sup 2} proton irradiated BiFeO{sub 3} samples are 41.36, 51.26, and 7.38% and 41.03, 50.90, and 8.07%, respectively. Our experimental observation suggests that the increase in the paramagnetic area ratio is due to the disappearance of superexchange interaction, resulted from the removal of the oxygen with proton irradiation. Also, the appearance of the weak ferromagnetic behavior is caused by the breaking of the antiferromagnetic coupling.

  2. Relative degradation of near infrared avalanche photodiodes from proton irradiation

    NASA Technical Reports Server (NTRS)

    Becker, Heidi; Johnston, Allan H.

    2004-01-01

    InGaAs and Ge avalanche photodiodes are compared for the effects of 63-MeV protons on dark current. Differences in displacement damage factors are discussed as they relate to structural differences between devices.

  3. Proton irradiation of stem cells: Radiation damage and chemical radioprotection

    NASA Technical Reports Server (NTRS)

    Riley, R. C.; Montour, J. L.; Gurney, C. W.

    1972-01-01

    Effects of high energy protons on erythropoietic stem cells and radioprotection by chemicals were investigated in NASA Space Radiation Effects Laboratory. The effects of a parallel beam of 600 MeV protons. The fluence, when converted to dose, were referenced to the synchrocyclotron beam monitors which were then used to administer radiation exposures. Mice were given graded doses to 300 rads to determine dose-response curve. Other mice received saline, AET, or 5-hydroxytryptamine 10 to 15 minutes before exposure.

  4. Single shot cell irradiations with laser-driven protons

    SciTech Connect

    Humble, N.; Schmid, T. E.; Zlobinskaya, O.; Wilkens, J. J.; Allinger, K.; Hilz, P.; Ma, W.; Reinhardt, S.; Bin, J.; Kiefer, D.; Schreiber, J.; Drexler, G. A.; Friedl, A.

    2013-07-26

    Ion beams are relevant for radiobiological studies in basic research and for application in tumor therapy. Here we present a method to generate nanosecond proton bunches with single shot doses of up to 7 Gray by a tabletop high-power laser. Although in their infancy, laser-ion accelerators allow studying fast radiobiological processes at small-scale laboratories as exemplarily demonstrated by measurements of the relative biological effectiveness of protons in human tumor cells.

  5. Correlation of electron and proton irradiation-induced damage in InP solar cells

    NASA Technical Reports Server (NTRS)

    Walters, Robert J.; Summers, Geoffrey P.; Messenger, Scott R.; Burke, Edward A.

    1996-01-01

    The measured degradation of epitaxial shallow homojunction n(+)/p InP solar cells under 1 MeV electron irradiation is correlated with that measured under 3 MeV proton irradiation based on 'displacement damage dose'. The measured data is analyzed as a function of displacement damage dose from which an electron to proton dose equivalency ratio is determined which enables the electron and proton degradation data to be described by a single degradation curve. It is discussed how this single curve can be used to predict the cell degradation under irradiation by any particle energy. The degradation curve is used to compare the radiation response of InP and GaAs/Ge cells on an absolute damage energy scale. The comparison shows InP to be inherently more resistant to displacement damage deposition than the GaAs/Ge.

  6. Scintillation imaging of air during proton and carbon-ion beam irradiations

    NASA Astrophysics Data System (ADS)

    Yamamoto, Seiichi; Toshito, Toshiyuki; Akagi, Takashi; Yamashita, Tomohiro; Komori, Masataka

    2016-10-01

    We previously reported that the luminescence imaging of water during proton or carbon-ion irradiation is possible using a charge-coupled device (CCD) camera, and these luminescence images can be used for the range estimations for these therapies. In the images during these irradiations to water phantoms, we observed scintillation images in the air parts. We conducted analysis of these images during proton and carbon-ion irradiations to use them for beam width estimations. We set profiles on the air part of the luminescence images of water during 100.2 MeV proton and 241.5 MeV/n carbon-ion irradiations. We estimated the widths of the beams from the scintillation images and compared them with those by simulation results. We also estimated the intensity and light spectrum of the scintillation of air and compared with those of the luminescence of water. The estimated widths of the proton and carbon-ion beams from the scintillation images of air were almost the same as those measured with simulations. The intensities of the scintillation of air were 3% and 5% of those of the luminescence of water for the proton and carbon-ion beams, respectively. The light spectrum of the scintillation of air peaked around 350-450 nm while those of luminescence of water showed wide distribution which peaked 450-550 nm. We confirmed that scintillation imaging of air during proton and carbon-ion beam irradiations were possible. The scintillation imaging of air could be used for the width estimations of proton and carbon-ion beams.

  7. Proton irradiation induced defects in GaN: Rutherford backscattering and thermally stimulated current studies

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Nishikata, N.; Kamioka, K.; Kuriyama, K.; Kushida, K.

    2016-03-01

    The proton irradiation induced defects in GaN are studied by combining elastic recoil detection analysis (ERDA), thermally stimulated current (TSC), and Rutherford backscattering spectroscopy (RBS) measurements. The proton irradiation (peak concentration: 1.0 × 1015 cm-2) into GaN films with a thickness of 3 μm is performed using a 500 keV implanter. The proton concentration by a TRIM simulation is maximum at 3600 nm in depth, which means that the proton beam almost passes through the GaN film. The carrier concentration decreases three orders of magnitude to 1015 cm-3 by the proton irradiation, suggesting the existence of the proton irradiation-induced defects. The ERDA measurements using the 1.5 MeV helium beam can evaluate hydrogen from the surface to ∼300 nm. The hydrogen concentration at ∼220 nm is ∼8.3 × 1013 cm-2 and ∼1.0 × 1014 cm-2 for un-irradiated and as-irradiated samples, respectively, suggesting that electrical properties are almost not affected by hydrogen. TSC measurements show a broad spectrum at around 110 K which can be divided into three traps, P1 (ionization energy 173 meV), P2 (251 meV), and P3 (330 meV). The peak intensity of P1 is much larger than that of P2 and P3. These traps are related to the N vacancy and/or complex involving N vacancy (P1), neutral Ga vacancy (VGa) (P2), and complex involving VGa (P3). The Ga displacement concentration evaluated by RBS measurements is 1.75 × 1019 cm-3 corresponding to 1/1000 of the Ga concentration in GaN. The observed Ga displacement may be origins of P2 and P3 traps.

  8. Triphasic low-dose response in zebrafish embryos irradiated by microbeam protons.

    PubMed

    Choi, Viann Wing Yan; Yum, Emily Hoi Wa; Konishi, Teruaki; Oikawa, Masakazu; Cheng, Shuk Han; Yu, Kwan Ngok

    2012-01-01

    The microbeam irradiation system (Single-Particle Irradiation System to Cell, acronym as SPICE) at the National Institute of Radiological Sciences (NIRS), Japan, was employed to irradiate dechorionated zebrafish embryos at the 2-cell stage at 0.75 h post fertilization (hpf) by microbeam protons. Either one or both of the cells of the embryos were irradiated with 10, 20, 40, 50, 80, 100, 160, 200, 300 and 2000 protons each with an energy of 3.37 MeV. The embryos were then returned back to the incubator until 24 hpf for analyses. The levels of apoptosis in zebrafish embryos at 25 hpf were quantified through terminal dUTP transferase-mediated nick end-labeling (TUNEL) assay, with the apoptotic signals captured by a confocal microscope. The results revealed a triphasic dose-response for zebrafish embryos with both cells irradiated at the 2-cell stage, namely, (1) increase in apoptotic signals for < 200 protons (< 30 mGy), (2) hormesis to reduce the apoptotic signals below the spontaneous number for 200-400 protons (at doses of 30-60 mGy), and (3) increase in apoptotic signals again for > 600 protons (at doses > 90 mGy). The dose response for zebrafish embryos with only one cell irradiated at the 2-cell stage was also likely a triphasic one, but the apoptotic signals in the first zone (< 200 protons or < 30 mGy) did not have significant differences from those of the background. At the same time, the experimental data were in line with induction of radiation-induced bystander effect as well as rescue effect in the zebrafish embryos, particular in those embryos with unirradiated cells.

  9. Low Temperature Sheet Forming

    NASA Astrophysics Data System (ADS)

    Voges-Schwieger, Kathrin; Hübner, Sven; Behrens, Bernd-Arno

    2011-05-01

    Metastable austenitic stainless steels change their lattice during forming operations by strain-induced alpha'-martensite formation. Temperatures below T = 20° C can accelerate the phase transformation while temperatures above T = 60° C may suppress the formation of martensite during the forming operation. In past investigations, the effect of high-strength martensitic regions in an austenitic ductile lattice was used in crash relevant parts for transportation vehicles. The local martensitic regions act as reinforcements leading to an increase in crash energy absorption. Moreover, they control the folding behavior as well as the force-distance-characteristic and increase the buckling resistance. This paper deals with a concerted thermomechanical drawing process to increase the local formation of alpha'-martensite caused by low temperatures.

  10. Low temperature latching solenoid

    NASA Technical Reports Server (NTRS)

    Wang, W. S. (Inventor)

    1981-01-01

    A magnetically latching solenoid includes a pull-in coil and a delatching coil. Each of the coils is constructed with a combination of wire materials, including material of low temperature coefficient of resistivity to enable the solenoid to be operated at cryogenic temperatures while maintaining sufficient coil resistance. An armature is spring-based toward a first position, that may extend beyond the field of force of a permanent magnet. When voltage is temporarily applied across the pull-in magnet, the induced electromagnetic forces overcome the spring force and pulls the armature to a second position within the field of the permanent magnet, which latches the armature in the pulled-in position. Application of voltage across the delatching coil induces electromagnetic force which at least partially temporarily nullifies the field of the permanent magnet at the armature, thereby delatching the armature and allowing the spring to move the armature to the first position.

  11. Tensile properties of vanadium-base alloys irradiated in the Fusion-1 low-temperature experiment in the BOR-60 reactor

    SciTech Connect

    Tsai, H.; Gazda, J.; Nowicki, L.J.; Billone, M.C.; Smith, D.L.

    1998-09-01

    The irradiation has been completed and the test specimens have been retrieved from the lithium-bonded capsule at the Research Institute of Atomic Reactors (RIAR) in Russia. During this reporting period, the Argonne National Laboratory (ANL) tensile specimens were received from RIAR and initial testing and examination of these specimens at ANL has been completed. The results, corroborating previous findings showed a significant loss of work hardening capability in the materials. There appears to be no significant difference in behavior among the various heats of vanadium-base alloys in the V-(4-5)Cr-(4-5)Ti composition range. The variations in the preirradiation annealing conditions also produced no notable differences.

  12. Redistribution of components in the niobium-silicon system under high-temperature proton irradiation

    SciTech Connect

    Afonin, N. N.; Logacheva, V. A. Khoviv, A. M.

    2011-12-15

    The redistribution of components in the niobium-silicon system during magnetron-assisted sputtering of niobium, vacuum annealing, and high-temperature proton irradiation is studied. It is established that, during magnetron-assisted sputtering followed by vacuum annealing, silicon penetrates through the metal film to the outer boundary of the film. Under high-temperature proton irradiation, the suppression of the diffusion of niobium into silicon is observed. This effect is attributed to the high concentration of radiation vacancies in the region of the Nb/Si interphase boundary.

  13. Impact of proton irradiation on deep level states in n-GaN

    SciTech Connect

    Zhang, Z.; Arehart, A. R.; Cinkilic, E.; Ringel, S. A.; Chen, J.; Zhang, E. X.; Fleetwood, D. M.; Schrimpf, R. D.; McSkimming, B.; Speck, J. S.

    2013-07-22

    Deep levels in 1.8 MeV proton irradiated n-type GaN were systematically characterized using deep level transient spectroscopies and deep level optical spectroscopies. The impacts of proton irradiation on the introduction and evolution of those deep states were revealed as a function of proton fluences up to 1.1 × 10{sup 13} cm{sup −2}. The proton irradiation introduced two traps with activation energies of E{sub C} - 0.13 eV and 0.16 eV, and a monotonic increase in the concentration for most of the pre-existing traps, though the increase rates were different for each trap, suggesting different physical sources and/or configurations for these states. Through lighted capacitance voltage measurements, the deep levels at E{sub C} - 1.25 eV, 2.50 eV, and 3.25 eV were identified as being the source of systematic carrier removal in proton-damaged n-GaN as a function of proton fluence.

  14. Scaling Laws for Proton Acceleration from the Rear Surface of Laser-Irradiated Thin Foils

    NASA Astrophysics Data System (ADS)

    Fuchs, J.; Antici, P.; d'Humières, E.; Lefebvre, E.; Borghesi, M.; Brambrink, E.; Cecchetti, C. A.; Kaluza, M.; Malka, V.; Manclossi, M.; Meyroneinc, S.; Mora, P.; Schreiber, J.; Toncian, T.; Pépin, H.; Audebert, P.

    2006-04-01

    In the last few years, intense research has been conducted on the topic of laser-accelerated ion sources and their applications. Ultra-bright beams of multi-MeV protons are produced by irradiating thin metallic foils with ultra-intense short laser pulses. These sources open new opportunities for ion beam generation and control, and could stimulate development of compact ion accelerators for many applications, in particular proton therapy of deep-seated tumours. Here we show that scaling laws deduced from fluid models reproduce well the acceleration of proton beams for a large range of laser and target parameters. These scaling laws show that, in our regime, there is an optimum in the laser pulse duration of ˜200 fs-1 ps, with a needed laser energy level of 30 to 100 J, in order to achieve e.g. 200 MeV energy protons necessary for proton therapy.

  15. The risk of developing a second cancer after receiving craniospinal proton irradiation

    PubMed Central

    Newhauser, Wayne D; Fontenot, Jonas D; Mahajan, Anita; Kornguth, David; Stovall, Marilyn; Zheng, Yuanshui; Taddei, Phillip J; Mirkovic, Dragan; Mohan, Radhe; Cox, James D; Woo, Shiao

    2014-01-01

    The purpose of this work was to compare the risk of developing a second cancer after craniospinal irradiation using photon versus proton radiotherapy by means of simulation studies designed to account for the effects of neutron exposures. Craniospinal irradiation of a male phantom was calculated for passively-scattered and scanned-beam proton treatment units. Organ doses were estimated from treatment plans; for the proton treatments, the amount of stray radiation was calculated separately using the Monte Carlo method. The organ doses were converted to risk of cancer incidence using a standard formalism developed for radiation protection purposes. The total lifetime risk of second cancer due exclusively to stray radiation was 1.5% for the passively scattered treatment versus 0.8% for the scanned proton beam treatment. Taking into account the therapeutic and stray radiation fields, the risk of second cancer from intensity-modulated radiation therapy and conventional radiotherapy photon treatments were 7 and 12 times higher than the risk associated with scanned-beam proton therapy, respectively, and 6 and 11 times higher than with passively scattered proton therapy, respectively. Simulations revealed that both passively scattered and scanned-beam proton therapies confer significantly lower risks of second cancers than 6MV conventional and intensity-modulated photon therapies. PMID:19305036

  16. Observations of defect structure evolution in proton and Ni ion irradiated Ni-Cr binary alloys

    NASA Astrophysics Data System (ADS)

    Briggs, Samuel A.; Barr, Christopher M.; Pakarinen, Janne; Mamivand, Mahmood; Hattar, Khalid; Morgan, Dane D.; Taheri, Mitra; Sridharan, Kumar

    2016-10-01

    Two binary Ni-Cr model alloys with 5 wt% Cr and 18 wt% Cr were irradiated using 2 MeV protons at 400 and 500 °C and 20 MeV Ni4+ ions at 500 °C to investigate microstructural evolution as a function of composition, irradiation temperature, and irradiating ion species. Transmission electron microscopy (TEM) was applied to study irradiation-induced void and faulted Frank loops microstructures. Irradiations at 500 °C were shown to generate decreased densities of larger defects, likely due to increased barriers to defect nucleation as compared to 400 °C irradiations. Heavy ion irradiation resulted in a larger density of smaller voids when compared to proton irradiations, indicating in-cascade clustering of point defects. Cluster dynamics simulations were in good agreement with the experimental findings, suggesting that increases in Cr content lead to an increase in interstitial binding energy, leading to higher densities of smaller dislocation loops in the Ni-18Cr alloy as compared to the Ni-5Cr alloy.

  17. Void swelling and precipitation in a titanium-modified austenitic stainless steel under proton irradiation

    NASA Astrophysics Data System (ADS)

    Kimoto, T.; Shiraishi, H.

    1985-07-01

    The correlation between void swelling and precipitation behavior in a 10% cold worked Fe-16.2Ni-14.6Cr-2.37Mo-1.79Mn-0.53Si-0.24Ti-0.06C alloy was examined with 200 keV proton irradiation. Swelling peak temperature after the proton irradiation to 10 dpa was about 823 K, and void swelling decreased steeply with increase in irradiation temperature from 823 to 923 K. Void swelling increased rapidly from 1.9 to 12.1% with increase in irradiation dose from 20 to 45 dpa at 873 K. Fine intragranular TiC precipitates, which were formed during initial stage of irradiation, dissolved gradually with increase in irradiation dose from 10 to 45 dpa at 873 K, while the amount of precipitation of needle-shaped Fe 2P phase containing titanium increased with increasing dose. The reduction of sink strength of the TiC precipitates due to the dissolution during irradiation was thought to cause the increase of swelling rate with increase in irradiation dose from 20 to 45 dpa at 873 K.

  18. Proton beam irradiation stimulates migration and invasion of human U87 malignant glioma cells

    PubMed Central

    Zaboronok, Alexander; Isobe, Tomonori; Yamamoto, Tetsuya; Sato, Eisuke; Takada, Kenta; Sakae, Takeji; Tsurushima, Hideo; Matsumura, Akira

    2014-01-01

    Migration and invasion of malignant glioma play a major role in tumor progression and can be increased by low doses of gamma or X-ray irradiation, especially when the migrated tumor cells are located at a distance from the main tumor mass or postoperative cavity and are irradiated in fractions. We studied the influence of proton beam irradiation on migration and invasion of human U87 malignant glioma (U87MG) cells. Irradiation at 4 and 8 Gy increased cell migration by 9.8% (±4, P = 0.032) and 11.6% (±6.6, P = 0.031) and invasion by 45.1% (±16.5, P = 0.04) and 40.5% (±12.7, P = 0.041), respectively. After irradiation at 2 and 16 Gy, cell motility did not differ from that at 0 Gy. We determined that an increase in proton beam irradiation dose to over 16 Gy might provide tumor growth control, although additional specific treatment might be necessary to prevent the potentially increased motility of glioma cells during proton beam therapy. PMID:24187331

  19. Comparison of proton microbeam and gamma irradiation for the radiation hardness testing of silicon PIN diodes

    NASA Astrophysics Data System (ADS)

    Jakšić, M.; Grilj, V.; Skukan, N.; Majer, M.; Jung, H. K.; Kim, J. Y.; Lee, N. H.

    2013-09-01

    Simple and cost-effective solutions using Si PIN diodes as detectors are presently utilized in various radiation-related applications in which excessive exposure to radiation degrades their charge transport properties. One of the conventional methods for the radiation hardness testing of such devices is time-consuming irradiation with electron beam or gamma-ray irradiation facilities, high-energy proton accelerators, or with neutrons from research reactors. Recently, for the purpose of radiation hardness testing, a much faster nuclear microprobe based approach utilizing proton irradiation has been developed. To compare the two different irradiation techniques, silicon PIN diodes have been irradiated with a Co-60 gamma radiation source and with a 6 MeV proton microbeam. The signal degradation in the silicon PIN diodes for both irradiation conditions has been probed by the IBIC (ion beam induced charge) technique, which can precisely monitor changes in charge collection efficiency. The results presented are reviewed on the basis of displacement damage calculations and NIEL (non-ionizing energy loss) concept.

  20. Cognitive effects of proton irradiation at differing energy levels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During exploratory class missions to space outside of the magnetic field of the Earth, astronauts will be exposed to various forms of radiation including solar particle events (SPE) which are predominantly composed of protons. As such it is important to characterize the cognitive effects of exposure...

  1. Low-Temperature Supercapacitors

    NASA Technical Reports Server (NTRS)

    Brandon, Erik J.; West, William C.; Smart, Marshall C.

    2008-01-01

    An effort to extend the low-temperature operational limit of supercapacitors is currently underway. At present, commercially available non-aqueous supercapacitors are rated for a minimum operating temperature of -40 C. A capability to operate at lower temperatures would be desirable for delivering power to systems that must operate in outer space or in the Polar Regions on Earth. Supercapacitors (also known as double-layer or electrochemical capacitors) offer a high power density (>1,000 W/kg) and moderate energy density (about 5 to 10 Wh/kg) technology for storing energy and delivering power. This combination of properties enables delivery of large currents for pulsed applications, or alternatively, smaller currents for low duty cycle applications. The mechanism of storage of electric charge in a supercapacitor -- at the electrical double-layer formed at a solid-electrode/liquid-electrolyte interface -- differs from that of a primary or secondary electrochemical cell (i.e., a battery) in such a manner as to impart a long cycle life (typically >10(exp 6) charge/discharge cycles).

  2. Low Temperature Oxidation Catalyst

    NASA Technical Reports Server (NTRS)

    1995-01-01

    One day soon homeowners everywhere may be protected from deadly carbon monoxide fumes, thanks to a device invented at NASA Langley Research Center in Hampton, Va. It uses a new class of low-temperature oxidation catalysts to convert carbon monoxide to non-toxic carbon dioxide at room temperature. It can also remove formaldehyde from the air. The catalysts initially were developed for research involving carbon dioxide lasers. Industry already has shown an interest. Rochester Gas and Electric Co., of Rochester, N.Y., has an agreement with NASA Langley to develop a product for habitable spaces such as homes, cars and aircraft. The Mantic Corp., of Salt Lake City, Utah, plans to use them in breathing apparatus, such as firefighter masks. The catalysts also have applications as trace-gas detectors, and in cold-engine emission control. To work, the catalysts - tin oxide and platinum - are applied to a surface. Air passing over the surface reacts with the catalysts, transforming carbon monoxide and formaldehyde. The device requires no energy for operation, doesn't need to be plugged in, has no moving parts and lasts a long time.

  3. Effects of proton and electron irradiation on the structural and tribological properties of MoS 2/polyimide

    NASA Astrophysics Data System (ADS)

    Liu, Baixing; Pei, Xianqiang; Wang, Qihua; Sun, Xiaojun; Wang, Tingmei

    2011-11-01

    To study the structural and tribological properties of MoS2/polyimide (MoS2/PI) composite under the irradiation environment of proton and electron, the MoS2/PI composites were investigated in a ground-based simulation facility, in which the energy of proton and electron was 25 keV and the flux was 2.5 × 1014 cm-2 s-1. The experimental results revealed that the simplex and combined irradiation of proton and electron induced bond break and cross-link, proton irradiation can break the PI bond easier than electron irradiation and then formed the graphite-like structure at surface area of the samples. Irradiation decreased the friction coefficient and wear rate remarkably of the composites comparing with the pristine one. The wear rate increased with the increasing of the proton and combined radiation time, and decreased with the electron radiation conditions.

  4. Effect of annealing on proton irradiated AlGaN/GaN based micro-Hall sensors

    SciTech Connect

    Abderrahmane, A.; Takahashi, H.; Tashiro, T.; Ko, P. J.; Okada, H.; Sandhu, A.; Sato, S.; Ohshima, T.

    2014-02-20

    The effect of annealing at 673 K on irradiated micro-Hall sensors irradiated with protons at 380keV and fluences of 10{sup 14}, 10{sup 15} and 10{sup 16} protons/cm{sup 2} is reported. Cathodoluminescence measurements were carried out at room temperature before and after annealing and showed improvement in the band edge band emission of the GaN layer. After annealing a sensor irradiated by 10{sup 15} protons/cm{sup 2} the device became operational with improvements in its magnetic sensitivity. All irradiated sensors showed improvement in their electrical characteristics after annealing.

  5. Microstructural changes of austenitic steels caused by proton irradiation under various conditions

    NASA Astrophysics Data System (ADS)

    Fukuda, T.; Sagisaka, M.; Isobe, Y.; Hasegawa, A.; Sato, M.; Abe, K.; Nishida, Y.; Kamada, T.; Kaneshima, Y.

    2000-12-01

    In austenitic steels used for light water reactors (LWRs), neutron irradiation induces many kinds of degradation. For example, irradiation assisted stress corrosion cracking (IASCC) and swelling are two forms of this degradation. Although there are a great number of studies on radiation induced segregation (RIS) and void swelling at high temperatures (>400° C) corresponding to fast and fusion reactor conditions, up to now there have been few irradiation studies at low temperatures. This paper presents microchemical and microstructural changes in type 347 and 310+Nb stainless steels due to light ion irradiation. These samples were implanted with He+ and irradiated with 2 MeV H2+ at 300°C, 350°C and 400°C. This simulated generation of transmutant He in a fusion environment. In addition, at 300°C test pieces stressed close to the yield stress were also irradiated with the same ions. The irradiation tests were carried out using the Dynamitron accelerator at Tohoku University.

  6. Detailed defect study in proton irradiated InP/Si solar cells

    NASA Astrophysics Data System (ADS)

    Walters, R. J.; Romero, M. J.; Araújo, D.; García, R.; Messenger, S. R.; Summers, G. P.

    1999-10-01

    A detailed study of the effects of proton irradiation-induced defects in heteroepitaxially grown InP/Si solar cells has been made through a combination of cathodoluminescence (CL), electron beam induced current (EBIC), and electrochemical capacitance versus voltage (ECV) carrier profiling measurements. The CL data indicate the distribution of nonradiative recombination centers both before and after proton irradiation, and temperature dependent and spectroscopic analysis of the CL signal give an estimate of the energies of the dominant defect levels. The EBIC data yield an estimate of the magnitude and spatial variation of the minority carrier diffusion length (L) in the base region. Values of L determined from EBIC measurements made on solar cells irradiated by protons ranging in energy from 0.1 up to 4.5 MeV follow a single curve when plotted versus displacement dose, Dd, allowing a single proton damage coefficient to be determined. The ECV measurements show the evolution of the carrier concentration profile in the cell under irradiation, as carrier removal first depletes and eventually type converts the base region. From an in-depth analysis of the combined data, the physical defects that give rise the radiation-induced energy levels are suggested, and a detailed understanding of the physical mechanisms causing the radiation response of InP/Si solar cells is developed.

  7. Doubling of the Critical Current Density of 2G-YBCO Coated Conductors through proton irradiation

    NASA Astrophysics Data System (ADS)

    Welp, Ulrich; Jia, Ying; Kwok, Wai-Kwong; Rupich, Marty; Fleshler, Steven; Kayani, Asfghar

    2013-03-01

    We report on magnetization and transport measurements of the critical current density of commercial 2G YBCO coated conductors before and after proton irradiation. The samples were irradiated along the c-axis with 4 MeV protons to a fluence of 1.5x1016 p/cm2. We find that at temperatures below 50 K, proton irradiation increases Jc by a factor of 2 in low fields and increases up to 2.5 in fields of 7 T. At 77 K, proton irradiation is less effective in enhancing the critical current. Doubling of Jc in fields of several Tesla and at temperatures below 50 K will be highly beneficial for applications of coated conductors in rotating machinery, generators and magnet coils. - Work supported by the US DoE-BES funded Energy Frontier Research Center (YJ), and by Department of Energy, Office of Science, Office of Basic Energy Sciences (UW, WKK), under Contract No. DE-AC02-06CH11357.

  8. A setup for soft proton irradiation of X-ray detectors for future astronomical space missions

    NASA Astrophysics Data System (ADS)

    Diebold, Sebastian; Azzarello, Philipp; Del Monte, Ettore; Feroci, Marco; Jochum, Josef; Kendziorra, Eckhard; Perinati, Emanuele; Rachevski, Alexandre; Santangelo, Andrea; Tenzer, Christoph; Vacchi, Andrea; Zampa, Gianluigi; Zampa, Nicola

    2013-09-01

    Protons that are trapped in the Earth's magnetic field are one of the main threats to astronomical X-ray observatories. Soft protons, in the range from tens of keV up to a few MeV, impinging on silicon X-ray detectors can lead to a significant degradation of the detector performance. Especially in low earth orbits an enhancement of the soft proton flux has been found. A setup to irradiate detectors with soft protons has been constructed at the Van-de-Graaff accelerator of the Physikalisches Institut of the University of Tübingen. Key advantages are a high flux uniformity over a large area, to enable irradiations of large detectors, and a monitoring system for the applied fluence, the beam uniformity, and the spectrum, that allows testing of detector prototypes in early development phases, when readout electronics are not yet available. Two irradiation campaigns have been performed so far with this setup. The irradiated detectors are silicon drift detectors, designated for the use on-board the LOFT space mission. This paper gives a description of the experimental setup and the associated monitoring system.

  9. Proton irradiation of conventional and lithium solar cells - 11-37 MeV

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Carter, J. R.

    1974-01-01

    Conventional n/p and lithium solar cells were irradiated with 11- to 37-MeV protons. The energy dependence of the solar cell degradation, calculated from electrical parameters and lifetime measurements, is shown to be very slight. Damage coefficients for the n/p cells are calculated. Annealing characteristics of both the lithium cells and the n/p cells are presented.

  10. High-temperature annealing of proton irradiated beryllium - A dilatometry-based study

    NASA Astrophysics Data System (ADS)

    Simos, Nikolaos; Elbakhshwan, Mohamed; Zhong, Zhong; Ghose, Sanjit; Savkliyildiz, Ilyas

    2016-08-01

    Ssbnd 200 F grade beryllium has been irradiated with 160 MeV protons up to 1.2 1020 cm-2 peak fluence and irradiation temperatures in the range of 100-200 °C. To address the effect of proton irradiation on dimensional stability, an important parameter in its consideration in fusion reactor applications, and to simulate high temperature irradiation conditions, multi-stage annealing using high precision dilatometry to temperatures up to 740 °C were conducted in air. X-ray diffraction studies were also performed to compliment the macroscopic thermal study and offer a microscopic view of the irradiation effects on the crystal lattice. The primary objective was to qualify the competing dimensional change processes occurring at elevated temperatures namely manufacturing defect annealing, lattice parameter recovery, transmutation 4He and 3H diffusion and swelling and oxidation kinetics. Further, quantification of the effect of irradiation dose and annealing temperature and duration on dimensional changes is sought. The study revealed the presence of manufacturing porosity in the beryllium grade, the oxidation acceleration effect of irradiation including the discontinuous character of oxidation advancement, the effect of annealing duration on the recovery of lattice parameters recovery and the triggering temperature for transmutation gas diffusion leading to swelling.

  11. Results of hybrid photodiode irradiation by 200 MeV protons

    SciTech Connect

    Baumbaugh A. et al.

    2001-12-03

    Hybrid Photodiodes (HPD, [1]) will be used as the photodetector for the Compact Muon Solenoid (CMS) Hadron Calorimeter (HCAL) readout [2]. The HPDs are required to operate in a high radiation environment, where the HCAL detector will receive a total ionizing dose of about 330 rads and a fluence of 4 x 10{sup 11} n/cm{sup 2} over a 10 year running period [3]. Effects of HPD irradiation by low energy neutrons were studied and reported previously [1]. In these studies, high energy protons are used to study possible effects of single event burnout [4], since high energy protons are more likely to induce large energy transfer within the HPD silicon. The HPDs were irradiated by 200 MeV protons at the Indiana University Cyclotron Facility [IUCF, 5]. The results of the study are presented.

  12. Response of 9Cr-ODS Steel to Proton Irradiation at 400 °C

    SciTech Connect

    Jianchao He; Farong Wan; Kumar Sridharan; Todd R. Allen; A. Certain; Y. Q. Wu

    2014-09-01

    The stability of Y–Ti–O nanoclusters, dislocation structure, and grain boundary segregation in 9Cr-ODS steels has been investigated following proton irradiation at 400 °C with damage levels up to 3.7 dpa. A slight coarsening and a decrease in number density of nanoclusters were observed as a result of irradiation. The composition of nanoclusters was also observed to change with a slight increase of Y and Cr concentration in the nanoclusters following irradiation. Size, density, and composition of the nanoclusters were investigated as a function of nanocluster size, specifically classified to three groups. In addition to the changes in nanoclusters, dislocation loops were observed after irradiation. Finally, radiation-induced enrichment of Cr and depletion of W were observed at grain boundaries after irradiation.

  13. Accumulation and annealing of radiation defects and the hydrogen effect thereon in an austenitic steel 16Cr15Ni3Mo1Ti upon low-temperature neutron and electron irradiation

    NASA Astrophysics Data System (ADS)

    Arbuzov, V. L.; Gothchitskii, B. N.; Danilov, S. E.; Zaluzhnyi, A. G.; Zuev, Yu. N.; Kar'kin, A. E.; Parkhomenko, V. D.; Sagaradze, V. V.

    2016-01-01

    The effect of hydrogen, accumulation and annealing of radiation defects on the physicomechanical properties of an austenitic Kh16N15M3T1 steel (16Cr15Ni3Mo1Ti) has been investigated upon low-temperature (77 K) neutron and electron irradiations. It has been shown that, when its concentration is about 300 at ppm, hydrogen reduces plasticity by 25%. The presence of helium (2.0-2.5 at ppm) introduced by the tritium-trick method exerts an effect on the yield strength and hardly affects embrittlement. Upon both electron and neutron irradiation, there is a linear relation between the increment of the yield strength and the square root of the increment of the residual electrical resistivity (the concentration of radiation defects). The annealing of vacancies occurs in the neighborhood of 300 K (energy for vacancy migration is 1.0-1.0 eV). Vacancy clusters dissociate near 480 K (energy for dissociation is 1.4-1.5 eV).

  14. Enhanced critical currents of commercial 2G superconducting coated conductors through proton irradiation

    NASA Astrophysics Data System (ADS)

    Welp, Ulrich; Leroux, M.; Kihlstrom, K. J.; Kwok, W.-K.; Koshelev, A. E.; Miller, D. J.; Rupich, M. W.; Fleshler, S.; Malozemoff, A. P.; Kayani, A.

    2015-03-01

    We report on magnetization and transport measurements of the critical current density, Jc, of commercial 2G YBCO coated conductors before and after proton irradiation. The samples were irradiated along the c-axis with 4 MeV protons. Proton irradiation produces a mixed pinning landscape composed of pre-existing rare earth particles and a uniform distribution of irradiation induced nm-sized defects. This pinning landscape strongly reduces the suppression of Jc in magnetic fields resulting in a doubling of Jc in a field of ~ 4T. The irradiation dose-dependence of Jc is characterized by a temperature and field dependent sweat spot that at 5 K and 6 T occurs around 20x1016 p/cm2. Large-scale time dependent Ginzburg-Landau simulations yield a good description of our results. This work supported by the Center for Emergent Superconductivity, an Energy Frontier Research Center funded by the U.S. D.O.E., Office of Science, Office of Basic Energy Sciences (KK, ML, AEK) and by the D.O.E, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 (UW, WKK).

  15. Effects of proton irradiation on nanocluster precipitation in ferritic steel containing fcc alloying additions

    SciTech Connect

    Zhang, Zhongwu; Liu, C T; Wang, Xun-Li; Miller, Michael K; Ma, Dong; Chen, Guang; Williams, J R; Chin, Bryan

    2012-01-01

    Newly-developed precipitate-strengthened ferritic steels with and without pre-existing nanoscale precipitates were irradiated with 4 MeV protons to a dose of ~5 mdpa at 50 C and subsequently examined by nanoindentation and atom probe tomography (APT). Irradiation-enhanced precipitation and coarsening of pre-existing nanoscale precipitates were observed. Copper partitions to the precipitate core along with a segregation of Ni, Al and Mn to the precipitate/matrix interface after both thermal aging and proton irradiation. Proton irradiation induces the precipitation reaction and coarsening of pre-existing nanoscale precipitates, and these results are similar to a thermal aging process. The precipitation and coarsening of nanoscale precipitates are responsible for the changes in hardness. The observation of the radiation-induced softening is essentially due to the coarsening of the pre-existing Cu-rich nanoscale precipitates. The implication of the precipitation on the embrittlement of reactor-pressure-vessel steels after irradiation is discussed.

  16. Defocusing beam line design for an irradiation facility at the TAEA SANAEM Proton Accelerator Facility

    NASA Astrophysics Data System (ADS)

    Gencer, A.; Demirköz, B.; Efthymiopoulos, I.; Yiğitoğlu, M.

    2016-07-01

    Electronic components must be tested to ensure reliable performance in high radiation environments such as Hi-Limu LHC and space. We propose a defocusing beam line to perform proton irradiation tests in Turkey. The Turkish Atomic Energy Authority SANAEM Proton Accelerator Facility was inaugurated in May 2012 for radioisotope production. The facility has also an R&D room for research purposes. The accelerator produces protons with 30 MeV kinetic energy and the beam current is variable between 10 μA and 1.2 mA. The beam kinetic energy is suitable for irradiation tests, however the beam current is high and therefore the flux must be lowered. We plan to build a defocusing beam line (DBL) in order to enlarge the beam size, reduce the flux to match the required specifications for the irradiation tests. Current design includes the beam transport and the final focusing magnets to blow up the beam. Scattering foils and a collimator is placed for the reduction of the beam flux. The DBL is designed to provide fluxes between 107 p /cm2 / s and 109 p /cm2 / s for performing irradiation tests in an area of 15.4 cm × 21.5 cm. The facility will be the first irradiation facility of its kind in Turkey.

  17. Proton irradiation of a swept charge device at cryogenic temperature and the subsequent annealing

    NASA Astrophysics Data System (ADS)

    Gow, J. P. D.; Smith, P. H.; Pool, P.; Hall, D. J.; Holland, A. D.; Murray, N. J.

    2015-01-01

    A number of studies have demonstrated that a room temperature proton irradiation may not be sufficient to provide an accurate estimation of the impact of the space radiation environment on detector performance. This is a result of the relationship between defect mobility and temperature, causing the performance to vary subject to the temperature history of the device from the point at which it was irradiated. Results measured using Charge Coupled Devices (CCD) irradiated at room temperature therefore tend to differ from those taken when the device was irradiated at a cryogenic temperature, more appropriate considering the operating conditions in space, impacting the prediction of in-flight performance. This paper describes the cryogenic irradiation, and subsequent annealing of an e2v technologies Swept Charge Device (SCD) CCD236 irradiated at -35.4°C with a 10 MeV equivalent proton fluence of 5.0 × 108 protons · cm-2. The CCD236 is a large area (4.4 cm2) X-ray detector that will be flown on-board the Chandrayaan-2 and Hard X-ray Modulation Telescope spacecraft, in the Chandrayaan-2 Large Area Soft X-ray Spectrometer and the Soft X-ray Detector respectively. The SCD is readout continually in order to benefit from intrinsic dither mode clocking, leading to suppression of the surface component of the dark current and allowing the detector to be operated at warmer temperatures than a conventional CCD. The SCD is therefore an excellent choice to test and demonstrate the variation in the impact of irradiation at cryogenic temperatures in comparison to a more typical room temperature irradiation.

  18. Controlled intensity emission from patterned porous silicon using focused proton beam irradiation

    SciTech Connect

    Teo, E.J.; Mangaiyarkarasi, D.; Breese, M.B.H.; Bettiol, A.A.; Blackwood, D.J.

    2004-11-08

    We have fabricated light emitting porous silicon micropatterns with controlled emission intensity. This has been achieved by direct write irradiation in heavily doped p-type silicon (0.02 {omega} cm) using a 2 MeV proton beam, focused to a spot size of 200 nm. After electrochemical etching in hydrofluoric acid, enhanced photoluminescence is observed from the irradiated regions. The intensity of light emission is proportional to the dose of the proton beam, so the PL intensity of the micropattern can be tuned and varied between adjacent regions on a single substrate. This behavior is in contrast to previous ion beam patterning of p-type silicon, as light is preferentially created as opposed to quenched at the irradiated regions.

  19. Persistent changes in neuronal structure and synaptic plasticity caused by proton irradiation

    PubMed Central

    Parihar, Vipan K.; Pasha, Junaid; Tran, Katherine K.; Craver, Brianna M.; Acharya, Munjal M.; Limoli, Charles L.

    2014-01-01

    Cranial radiotherapy is used routinely to control the growth of primary and secondary brain tumors, but often results in serious and debilitating cognitive dysfunction. In part due to the beneficial dose depth distributions that may spare normal tissue damage, the use of protons to treat CNS and other tumor types is rapidly gaining popularity. Astronauts exposed to lower doses of protons in the space radiation environment are also at risk for developing adverse CNS complications. To explore the consequences of whole body proton irradiation, mice were subjected to 0.1 and 1 Gy and analyzed for morphometric changes in hippocampal neurons 10 and 30 days following exposure. Significant dose-dependent reductions (~33%) in dendritic complexity were found, when dendritic length, branching and area were analyzed 30 days after exposure. At equivalent doses and times, significant reductions in the number (~30%) and density (50–75%) of dendritic spines along hippocampal neurons of the dentate gyrus were also observed. Immature spines (filopodia, long) exhibited the greatest sensitivity (1.5–3 fold) to irradiation, while more mature spines (mushroom) were more resistant to changes over a 1-month post-irradiation timeframe. Irradiated granule cell neurons spanning the subfields of the dentate gyrus showed significant and dose-responsive reductions in synaptophysin expression, while the expression of postsynaptic density protein (PSD-95) was increased significantly. These findings corroborate our past work using photon irradiation, and demonstrate for the first time, dose-responsive changes in dendritic complexity, spine density and morphology and synaptic protein levels following exposure to low dose whole body proton irradiation. PMID:24446074

  20. Proton irradiation damage of an annealed Alloy 718 beam window

    SciTech Connect

    Bach, H. T.; Anderoglu, O.; Saleh, T. A.; Romero, T. J.; Kelsey, C. T.; Olivas, E. R.; Sencer, B. H.; Dickerson, P. O.; Connors, M. A.; John, K. D.; Maloy, S. A.

    2015-04-01

    Mechanical testing and microstructural analysis was performed on an Alloy 718 window that was in use at the Los Alamos Neutron Science Center (LANSCE) Isotope Production Facility (IPF) for approximately 5 years. It was replaced as part of the IPF preventive maintenance program. The window was transported to the Wing 9 hot cells at the Chemical and Metallurgical Research (CMR) LANL facility, visually inspected and 3-mm diameter samples were trepanned from the window for mechanical testing and microstructural analysis. Shear punch testing and optical metallography was performed at the CMR hot cells. The 1-mm diameter shear punch disks were cut into smaller samples to further reduce radiation exposure dose rate using Focus Ion Beam (FIB) and microstructure changes were analyzed using a Transmission Electron Microscopy (TEM). Irradiation doses were determined to be ~0.2–0.7 dpa (edge) to 11.3 dpa (peak of beam intensity) using autoradiography and MCNPX calculations. The corresponding irradiation temperatures were calculated to be ~34–120 °C with short excursion to be ~47–220 °C using ANSYS. Mechanical properties and microstructure analysis results with respect to calculated dpa and temperatures show that significant work hardening occurs but useful ductility still remains. The hardening in the lowest dose region (~0.2–0.7 dpa) was the highest and attributed to the formation of γ" precipitates and irradiation defect clusters/bubbles whereas the hardening in the highest dose region (~11.3 dpa) was lower and attributed mainly to irradiation defect clusters and some thermal annealing.

  1. Proton irradiation damage of an annealed Alloy 718 beam window

    DOE PAGES

    Bach, H. T.; Anderoglu, O.; Saleh, T. A.; Romero, T. J.; Kelsey, C. T.; Olivas, E. R.; Sencer, B. H.; Dickerson, P. O.; Connors, M. A.; John, K. D.; et al

    2015-04-01

    Mechanical testing and microstructural analysis was performed on an Alloy 718 window that was in use at the Los Alamos Neutron Science Center (LANSCE) Isotope Production Facility (IPF) for approximately 5 years. It was replaced as part of the IPF preventive maintenance program. The window was transported to the Wing 9 hot cells at the Chemical and Metallurgical Research (CMR) LANL facility, visually inspected and 3-mm diameter samples were trepanned from the window for mechanical testing and microstructural analysis. Shear punch testing and optical metallography was performed at the CMR hot cells. The 1-mm diameter shear punch disks were cutmore » into smaller samples to further reduce radiation exposure dose rate using Focus Ion Beam (FIB) and microstructure changes were analyzed using a Transmission Electron Microscopy (TEM). Irradiation doses were determined to be ~0.2–0.7 dpa (edge) to 11.3 dpa (peak of beam intensity) using autoradiography and MCNPX calculations. The corresponding irradiation temperatures were calculated to be ~34–120 °C with short excursion to be ~47–220 °C using ANSYS. Mechanical properties and microstructure analysis results with respect to calculated dpa and temperatures show that significant work hardening occurs but useful ductility still remains. The hardening in the lowest dose region (~0.2–0.7 dpa) was the highest and attributed to the formation of γ" precipitates and irradiation defect clusters/bubbles whereas the hardening in the highest dose region (~11.3 dpa) was lower and attributed mainly to irradiation defect clusters and some thermal annealing.« less

  2. Proton irradiation damage of an annealed Alloy 718 beam window

    NASA Astrophysics Data System (ADS)

    Bach, H. T.; Anderoglu, O.; Saleh, T. A.; Romero, T. J.; Kelsey, C. T.; Olivas, E. R.; Sencer, B. H.; Dickerson, P. O.; Connors, M. A.; John, K. D.; Maloy, S. A.

    2015-04-01

    Mechanical testing and microstructural analysis was performed on an Alloy 718 window that was in use at the Los Alamos Neutron Science Center (LANSCE) Isotope Production Facility (IPF) for approximately 5 years. It was replaced as part of the IPF preventive maintenance program. The window was transported to the Wing 9 hot cells at the Chemical and Metallurgical Research (CMR) LANL facility, visually inspected and 3-mm diameter samples were trepanned from the window for mechanical testing and microstructural analysis. Shear punch testing and optical metallography was performed at the CMR hot cells. The 1-mm diameter shear punch disks were cut into smaller samples to further reduce radiation exposure dose rate using Focus Ion Beam (FIB) and microstructure changes were analyzed using a Transmission Electron Microscopy (TEM). Irradiation doses were determined to be ∼0.2-0.7 dpa (edge) to 11.3 dpa (peak of beam intensity) using autoradiography and MCNPX calculations. The corresponding irradiation temperatures were calculated to be ∼34-120 °C with short excursion to be ∼47-220 °C using ANSYS. Mechanical properties and microstructure analysis results with respect to calculated dpa and temperatures show that significant work hardening occurs but useful ductility still remains. The hardening in the lowest dose region (∼0.2-0.7 dpa) was the highest and attributed to the formation of γ″ precipitates and irradiation defect clusters/bubbles whereas the hardening in the highest dose region (∼11.3 dpa) was lower and attributed mainly to irradiation defect clusters and some thermal annealing.

  3. Studies of proton-irradiated cometary-type ice mixtures

    SciTech Connect

    Moore, M.H.; Donn, B.; Khanna, R.

    1983-06-01

    Cometary ice mixtures are studied in a laboratory experiment designed to simulate the temperature, pressure and radiation environments of the interstellar Oort cloud region, in order to test the hypothesized radiation synthesis mechanism for changing the characteristics of the outer few meters of a comet stored in the Oort cloud for 4.6 billion years. All experiments conducted confirm the synthesis of new molecular species in solid phase mixtures at 20 K. When CH4 is present in the irradiated ice mixture, long chained, voltaile hydrocarbon and CO2 are synthesized together with high molecular weight C compounds present in the room temperature residue. Due to radiation synthesis, about 1 percent of the ice was converted into a nonvolatile residue containing complicated C compounds not present in the blank samples. These results suggest that initial molecular abundances can be altered, and new species created, as a result of radiation synthesis. Irradiated mixtures exhibited thermoluminescence and pressure enhancements during warming, showing the synthesis of reactive species. Outbursts in new comets resulting from similar irradiation-induced exothermic activity would be expected to begin occurring at distances of the order of 100 AU. 40 references.

  4. Studies of proton-irradiated cometary-type ice mixtures

    NASA Astrophysics Data System (ADS)

    Moore, M. H.; Donn, B.; Khanna, R.; A'Hearn, M. F.

    1983-06-01

    Cometary ice mixtures are studied in a laboratory experiment designed to simulate the temperature, pressure and radiation environments of the interstellar Oort cloud region, in order to test the hypothesized radiation synthesis mechanism for changing the characteristics of the outer few meters of a comet stored in the Oort cloud for 4.6 billion years. All experiments conducted confirm the synthesis of new molecular species in solid phase mixtures at 20 K. When CH4 is present in the irradiated ice mixture, long chained, voltaile hydrocarbon and CO2 are synthesized together with high molecular weight C compounds present in the room temperature residue. Due to radiation synthesis, about 1 percent of the ice was converted into a nonvolatile residue containing complicated C compounds not present in the blank samples. These results suggest that initial molecular abundances can be altered, and new species created, as a result of radiation synthesis. Irradiated mixtures exhibited thermoluminescence and pressure enhancements during warming, showing the synthesis of reactive species. Outbursts in new comets resulting from similar irradiation-induced exothermic activity would be expected to begin occurring at distances of the order of 100 AU.

  5. Physiologic and Radiographic Evidence of the Distal Edge of the Proton Beam in Craniospinal Irradiation

    SciTech Connect

    Krejcarek, Stephanie C.; Grant, P. Ellen; Henson, John W.; Tarbell, Nancy J.; Yock, Torunn I. . E-mail: tyock@partners.org

    2007-07-01

    Purpose: Fatty replacement of bone marrow resulting from radiation therapy can be seen on T1-weighted magnetic resonance (MR) images. We evaluated the radiographic appearance of the vertebral bodies in children treated with proton craniospinal irradiation (CSI) to illustrate the distal edge effect of proton radiotherapy. Methods and Materials: The study cohort consisted of 13 adolescents aged 12-18 years who received CSI with proton radiotherapy at Massachusetts General Hospital. Ten of these patients had reached maximal or near-maximal growth. Proton beam radiation for these 10 patients was delivered to the thecal sac and exiting nerve roots only, whereas the remaining 3 patients had a target volume that included the thecal sac, exiting nerve roots, and entire vertebral bodies. Median CSI dose was 27 [range, 23.4-36] cobalt gray equivalent (CGE) given in 1.8-CGE fractions. Magnetic resonance images of the spine were obtained after completion of radiotherapy. Results: Magnetic resonance images of patients who received proton radiotherapy to the thecal sac only demonstrate a sharp demarcation of hyperintense T1-weighted signal in the posterior aspects of the vertebral bodies, consistent with radiation-associated fatty marrow replacement. Magnetic resonance images of the patients prescribed proton radiotherapy to the entire vertebral column had corresponding hyperintense T1-weighted signal involving the entire vertebral bodies. Conclusion: The sharp delineation of radiation-associated fatty marrow replacement in the vertebral bodies demonstrates the rapid decrease in energy at the edge of the proton beam. This provides evidence for a sharp fall-off in radiation dose and supports the premise that proton radiotherapy spares normal tissues unnecessary irradiation.

  6. External-Beam Accelerated Partial Breast Irradiation Using Multiple Proton Beam Configurations

    SciTech Connect

    Wang Xiaochun; Amos, Richard A.; Zhang Xiaodong; Taddei, Phillip J.; Woodward, Wendy A.; Hoffman, Karen E.; Yu, Tse Kuan; Tereffe, Welela; Oh, Julia; Perkins, George H.; Salehpour, Mohammad; Zhang, Sean X.; Sun, Tzou Liang; Gillin, Michael; Buchholz, Thomas A.; Strom, Eric A.

    2011-08-01

    Purpose: To explore multiple proton beam configurations for optimizing dosimetry and minimizing uncertainties for accelerated partial breast irradiation (APBI) and to compare the dosimetry of proton with that of photon radiotherapy for treatment of the same clinical volumes. Methods and Materials: Proton treatment plans were created for 11 sequential patients treated with three-dimensional radiotherapy (3DCRT) photon APBI using passive scattering proton beams (PSPB) and were compared with clinically treated 3DCRT photon plans. Monte Carlo calculations were used to verify the accuracy of the proton dose calculation from the treatment planning system. The impact of range, motion, and setup uncertainty was evaluated with tangential vs. en face beams. Results: Compared with 3DCRT photons, the absolute reduction of the mean of V100 (the volume receiving 100% of prescription dose), V90, V75, V50, and V20 for normal breast using protons are 3.4%, 8.6%, 11.8%, 17.9%, and 23.6%, respectively. For breast skin, with the similar V90 as 3DCRT photons, the proton plan significantly reduced V75, V50, V30, and V10. The proton plan also significantly reduced the dose to the lung and heart. Dose distributions from Monte Carlo simulations demonstrated minimal deviation from the treatment planning system. The tangential beam configuration showed significantly less dose fluctuation in the chest wall region but was more vulnerable to respiratory motion than that for the en face beams. Worst-case analysis demonstrated the robustness of designed proton beams with range and patient setup uncertainties. Conclusions: APBI using multiple proton beams spares significantly more normal tissue, including nontarget breast and breast skin, than 3DCRT using photons. It is robust, considering the range and patient setup uncertainties.

  7. Investigation on using high-energy proton beam for total body irradiation (TBI).

    PubMed

    Zhang, Miao; Qin, Nan; Jia, Xun; Zou, Wei J; Khan, Atif; Yue, Ning J

    2016-01-01

    This work investigated the possibility of using proton beam for total body irradia-tion (TBI). We hypothesized the broad-slow-rising entrance dose from a monoen-ergetic proton beam can deliver a uniform dose to patient with varied thickness. Comparing to photon-based TBI, it would not require any patient-specific com-pensator or beam spoiler. The hypothesis was first tested by simulating 250 MeV, 275 MeV, and 300 MeV protons irradiating a wedge-shaped water phantom in a paired opposing arrangement using Monte Carlo (MC) method. To allow ± 7.5% dose variation, the maximum water equivalent thickness (WET) of a treatable patient separation was 29 cm for 250 MeV proton, and > 40 cm for 275 MeV and 300 MeV proton. The compared 6 MV photon can only treat patients with up to 15.5 cm water-equivalent separation. In the second step, we simulated the dose deposition from the same beams on a patient's whole-body CT scan. The maximum patient separation in WET was 23 cm. The calculated whole-body dose variations were ± 8.9%, ± 9.0%, ± 9.6%, and ± 14% for 250 MeV proton, 275 MeV proton, 300 MeV proton, and 6 MV photon. At last, we tested the current machine capability to deliver a monoenergetic proton beam with a large uniform field. Experiments were performed on a compact double scattering single-gantry proton system. With its C-shaped gantry design, the source-to-surface distance (SSD) reached 7 m. The measured dose deposition curve had 22 cm relatively flat entrance region. The full width half maximum field size was measured 105 cm. The current scatter filter had to be redesigned to produce a uniform intensity at such treatment distance. In con-clusion, this work demonstrated the possibility of using proton beam for TBI. The current commercially available proton machines would soon be ready for such task. PMID:27685117

  8. In-situ proton irradiation and measurement of superconducting rf cavities under cryogenic conditions

    SciTech Connect

    Rusnak, B.; Haynes, W.B.; Chan, K.C.D.

    1997-08-01

    The Accelerator Production of Tritium (APT) Project is investigating using a superconducting linac for the high-energy portion of the accelerator. As this accelerator would be used to accelerate a high-current (100-mA) CW proton beam up to 1700 MeV, it is important to determine the effects of stray-beam impingement on the superconducting properties of a 700-MHz niobium cavity. To accomplish this, two 3000-MHz elliptical niobium cavities were placed in a cryostat, cooled to nominally 2 K in sub-atmospheric liquid helium, and irradiated with 798-MeV protons at up to 490 {pi}A average current. The elliptically shaped beam passed through the equatorial regions of both cavities in order to maximize sensitivity to any changes in the superconducting-surface resistance. Over the course of the experiment, 6x10{sup 16} protons were passed through the cavities. After irradiation, the cavities were warmed to 250 K, then recooled to investigate the effects of a room-temperature annealing cycle on the superconducting properties of the irradiated cavities. A detailed description of the experiment and the results shall be presented. These results are important to employing superconducting-rf technology to future high-intensity proton accelerators for use in research and transmutation technologies.

  9. Projecting EOL dark current distribution of proton irradiated CCDs

    NASA Astrophysics Data System (ADS)

    Flores, James S.

    2005-09-01

    Space instrument programs occasionally need an estimate of how dark current distribution of a silicon CCD changes versus proton radiation exposure and temperature. The task that is the subject of this article was started by adopting a relevant gamma distribution model produced by M.S. Robbins [1] and estimating its parameters, α and β, by using data acquired by Demara [2]. The fortuitous result was that α was found to depend solely on damage displacement dose and β was found to be practically equal to the native bulk dark current of silicon. These implications were tested with information from three published articles. In comparison with the published results, the model was found to be accurate within a factor of two.

  10. Proton irradiation effects on 2Gb flash memory

    SciTech Connect

    Wester, William; Nelson, Charles; Marriner, John

    2004-08-18

    The authors report total ionizing dose and single event effects on 2Gb Samsung flash memory devices after exposure to 200 MeV protons to various doses up to 83 krad(Si). They characterize observed failures and single event upsets on 22 devices from two different lots. Devices from both lots are robust to greater than 20 krad(Si) although they see evidence for lot-to-lot variation where only one lot appears robust up to about 50 krad(Si). Single event upsets are observed at a relatively low rate and are consistent with single isolated bit flips within registers that transfer bits to and from the flash memory cells.

  11. Further measurements of random telegraph signals in proton irradiated CCDs

    SciTech Connect

    Hopkins, I.H.

    1995-12-01

    The probability/incident proton for creation of a defect in a charge-coupled device (CCD) which shows dark current random telegraph signal (RTS) behavior has been measured for energies of 1.5, 10 and 46 MeV. The probability was found to be proportional to the non-ionizing energy loss (NIEL) for elastic collisions. Plots of RTS probability versus mean dark current indicate a correlation with the amount of field enhanced emission. If a pixel already has a defect showing field enhanced emission, it is more likely to show RTS effects. The amplitudes themselves are not correlated with the degree of field enhanced emission. An alternative to the bulk metastable defect model is proposed, based on the reorientation of the phosphorus-vacancy center in a high electric field.

  12. Energy from low temperature differences

    NASA Astrophysics Data System (ADS)

    Parsons, B. K.

    1985-05-01

    A number of energy conservation and alternative energy approaches utilize a low temperature heat source. Applications in this category include: solar ponds, ocean thermal energy conversion (OTEC), low temperature solar thermal, geothermal, and waste heat recovery and bottoming cycles. Low temperature power extraction techniques are presented and the differences between closed and open Rankine power cycles are discussed. Specific applications and technical areas of current research in OTEC along with a breakdown of plant operating conditions and a rough cost estimate illustrate how the use of low temperature power conversion technology can be cost effective.

  13. Creation of 3D microsculptures in PMMA by multiple angle proton irradiation

    NASA Astrophysics Data System (ADS)

    Andrea, T.; Rothermel, M.; Reinert, T.; Koal, T.; Butz, T.

    2011-10-01

    In recent years the technique of proton beam writing has established itself as a versatile method for the creation of microstructures in resist materials. While these structures can be almost arbitrary in two dimensions, the creation of genuine 3D structures remains a challenge. At the LIPSION accelerator facility a new approach has been developed which combines aspects of ion beam tomography, so far solely an analysis method, with proton beam writing. Key element is the targeted irradiation from multiple angles in order to obtain a much broader range of 3D microstructures than has hitherto been possible. PMMA columns with a diameter of ∼90 μm were used as raw material and placed in an upright position on top of a rotational axis. Using 2.25 MeV protons patterns corresponding to the silhouettes of the desired structures were written from two or more directions. In a subsequent step of chemical etching irradiated portions were dissolved, leaving behind the finished 3D sculpture. Various objects have been created. For the demonstration of the method a 70 μm high model of the Eiffel tower has been sculpted by irradiation from two angles. Using irradiation from three angles a 40 μm wide screw with right-handed thread could be crafted which might find applications in micromachining. Also, a cage structure with a pore size of ca. 20 μm was written with the intention to use it as a scaffold for the growth of biological cells.

  14. Recombination characteristics in 2-3 MeV protons irradiated FZ Si

    NASA Astrophysics Data System (ADS)

    Gaubas, E.; Čeponis, T.; Uleckas, A.; Vaitkus, J.; Raisanen, J.

    2010-01-01

    Combined analysis of the carrier recombination and generation lifetime as well as reverse recovery durations ( τ RR), dependent on proton irradiation fluence in the range of 7×10 12-7×10 14 p/cm 2, has been performed in FZ silicon PIN diodes and wafer structures. A δ-layer and triangle profiles of radiation induced defects were formed by varying energy of protons in the range 2-3 MeV. Carrier decay constituents and values of recombination lifetime have been evaluated by employing a microwave probed photoconductivity transient technique, while deep levels spectra ascribed to generation lifetime variations have been examined by exploiting capacitance deep-level transient (DLTS) spectroscopy. Recombination lifetime decreases from several μs to few ns, while DLTS spectra show an increase in the amplitude of a DLTS peak at 170 K with irradiation fluence. Transforms of DLTS spectra and a decrease in density of the majority carrier traps have been revealed after 24 h isochronal anneals in the range of temperatures of 80-420 °C. Inhomogeneous depth distribution of recombination lifetime in proton irradiated samples has been revealed from the cross-sectional scans of the excess carrier lifetime measured by MW-PC technique and compared for δ-layer and triangle profiles of radiation induced defects. After isochronal anneals, the τ RR changes its behaviour as a function of irradiation fluence.

  15. [DEMONSTRATION OF LIKELIHOOD OF THE NEGATIVE EFFECT OF PHYSICAL PROTECTION DURING TOTAL PROTON IRRADIATION OF MICE].

    PubMed

    Ivanov, A A; Bulynina, T M; Molokanov, A G; Vorozhtsova, S V; Utina, D M; Severyukhin, Yu S; Ushakov, I B

    2015-01-01

    The experiments were performed with outbred CD-1 male mice (SPF category). Total irradiation at 1.0; 2.5 and 5.0 Gy by protons with the average energy of 170 MeV was conducted in a level medical beam of the phasotron at the Joint Institute of Nuclear Investigations. Targets were 2 points of in-depth dose distribution, i.e. beam entrance of the object, and modified Bragg peak. As a physical protector, the comb filter increases linear energy transfer (LET) of 170 MeV entrance protons from 0.49 keV/μm to 1.6 keV/μm and, according to the bone marrow test, doubles the biological effectiveness of protons when comparing radiation doses that cause 37% inhibition of blood cell formation in the bone marrow. Physical protection increases dose rate from 0.37 Gy/min for entrance protons to 0.8 Gy/min for moderated protons which more than in thrice reduces time of irradiation needed to reach an equal radiobiological effect.

  16. [DEMONSTRATION OF LIKELIHOOD OF THE NEGATIVE EFFECT OF PHYSICAL PROTECTION DURING TOTAL PROTON IRRADIATION OF MICE].

    PubMed

    Ivanov, A A; Bulynina, T M; Molokanov, A G; Vorozhtsova, S V; Utina, D M; Severyukhin, Yu S; Ushakov, I B

    2015-01-01

    The experiments were performed with outbred CD-1 male mice (SPF category). Total irradiation at 1.0; 2.5 and 5.0 Gy by protons with the average energy of 170 MeV was conducted in a level medical beam of the phasotron at the Joint Institute of Nuclear Investigations. Targets were 2 points of in-depth dose distribution, i.e. beam entrance of the object, and modified Bragg peak. As a physical protector, the comb filter increases linear energy transfer (LET) of 170 MeV entrance protons from 0.49 keV/μm to 1.6 keV/μm and, according to the bone marrow test, doubles the biological effectiveness of protons when comparing radiation doses that cause 37% inhibition of blood cell formation in the bone marrow. Physical protection increases dose rate from 0.37 Gy/min for entrance protons to 0.8 Gy/min for moderated protons which more than in thrice reduces time of irradiation needed to reach an equal radiobiological effect. PMID:26554131

  17. Response of thyroid follicular cells to gamma irradiation compared to proton irradiation: II. The role of connexin 32

    NASA Technical Reports Server (NTRS)

    Green, L. M.; Tran, D. T.; Murray, D. K.; Rightnar, S. S.; Todd, S.; Nelson, G. A.

    2002-01-01

    The objective of this study was to determine whether connexin 32-type gap junctions contribute to the "contact effect" in follicular thyrocytes and whether the response is influenced by radiation quality. Our previous studies demonstrated that early-passage follicular cultures of Fischer rat thyroid cells express functional connexin 32 gap junctions, with later-passage cultures expressing a truncated nonfunctional form of the protein. This model allowed us to assess the role of connexin 32 in radiation responsiveness without relying solely on chemical manipulation of gap junctions. The survival curves generated after gamma irradiation revealed that early-passage follicular cultures had significantly lower values of alpha (0.04 Gy(-1)) than later-passage cultures (0.11 Gy(-1)) (P < 0.0001, n = 12). As an additional way to determine whether connexin 32 was contributing to the difference in survival, cultures were treated with heptanol, resulting in higher alpha values, with early-passage cultures (0.10 Gy(-1)) nearly equivalent to untreated late-passage cultures (0.11 Gy(-1)) (P > 0.1, n = 9). This strongly suggests that the presence of functional connexin 32-type gap junctions was contributing to radiation resistance in gamma-irradiated thyroid follicles. Survival curves from proton-irradiated cultures had alpha values that were not significantly different whether cells expressed functional connexin 32 (0.10 Gy(-1)), did not express connexin 32 (0.09 Gy(-1)), or were down-regulated (early-passage plus heptanol, 0.09 Gy(-1); late-passage plus heptanol, 0.12 Gy(-1)) (P > 0.1, n = 19). Thus, for proton irradiation, the presence of connexin 32-type gap junctional channels did not influence their radiosensitivity. Collectively, the data support the following conclusions. (1) The lower alpha values from the gamma-ray survival curves of the early-passage cultures suggest greater repair efficiency and/or enhanced resistance to radiation-induced damage, coincident with the

  18. Flux Pinning and Critical Current Densities in Proton Irradiated Single Crystal Yttrium Barium Copper Oxide.

    NASA Astrophysics Data System (ADS)

    Viswanathan, Hema Krishnan

    Radiation damage has been traditionally used to introduce artificial pinning centers into superconducting material in order to enhance their critical current densities. The objective of this study was to determine the effect of defects induced by irradiation with 3.5 MeV protons on the critical current densities and to investigate the structure of the defects using SQUID magnetization and magnetoresistive measurements. There are three general types of defects produced by proton irradiation at room temperature. They are (1) a relatively high concentration of point defects on all the sublattices, (2) clusters of point defects, and (3) the defect cascades. SQUID magnetization measurements suggest that the defect clusters and cascades are effective in pinning the vortices at 70 K for vec{rm H}|vec{rm c} axis. Additional contribution to pinning at 10 K for vec{rm H}|vec {rm c} axis comes from the vacancies formed upon irradiation with protons. The defect clusters seem to be the only contributors to pinning for vec{rm H}|vec{ rm ab} plane. The anisotropy of the critical current densities in detwinned crystals between field orientations parallel to the vec{ rm a} and vec{rm b} axes determined from magnetization measurements at 10 K consistently show that rm J_sp {c}{c}(vec H|vec b)>J_sp{c}{c}(vec H| vec a) at all fields after 2 irradiations and annealing for 2 and 4 weeks. The effect of proton irradiation on the resistive transition and the anisotropy of the defect structure was studied using angular dependence of the resistivity in rm YBa_2Cu_3O_{7 -delta} single crytals. The expected drop in resistivity when the field is aligned parallel to the vec{rm c} axis due to the alignment of the vortices with the defect cluster as observed in the case of the twin boundaries was absent.

  19. Synchrotron X-ray Microdiffraction Analysis of Proton Irradiated Polycrystalline Diamond Films

    NASA Technical Reports Server (NTRS)

    Newton, R. I.; Davidson, J. L.; Ice, G. E.; Liu, W.

    2004-01-01

    X-ray microdiffraction is a non-destructive technique that allows for depth-resolved, strain measurements with sub-micron spatial resolution. These capabilities make this technique promising for understanding the mechanical properties of MicroElectroMechanical Systems (MEMS). This investigation examined the local strain induced by irradiating a polycrystalline diamond thin film with a dose of 2x10(exp 17) H(+)per square centimeter protons. Preliminary results indicate that a measurable strain, on the order of 10(exp -3), was introduced into the film near the End of Range (EOR) region of the protons.

  20. Development of a Ne gas target for 22Na production by proton irradiation

    NASA Astrophysics Data System (ADS)

    Mandal, Bidhan Ch.; Barua, Luna; Das, Sujata Saha; Pal, Gautam

    2016-03-01

    The article presents the design and development of a neon gas target for the production of 22Na using a proton beam from the room temperature cyclotron in Variable Energy Cyclotron Centre, Kolkata. The target design is made to handle a beam power of 85 W (17 MeV, 5 μA). The design is based on simulation using the computer code FLUKA for the beam dump and CFD-CFX for target cooling. The target has been successfully used for the production of 22Na in a 6 day long 17 MeV, 5 μA proton irradiation run.

  1. Development of a Ne gas target for (22)Na production by proton irradiation.

    PubMed

    Mandal, Bidhan Ch; Barua, Luna; Das, Sujata Saha; Pal, Gautam

    2016-03-01

    The article presents the design and development of a neon gas target for the production of (22)Na using a proton beam from the room temperature cyclotron in Variable Energy Cyclotron Centre, Kolkata. The target design is made to handle a beam power of 85 W (17 MeV, 5 μA). The design is based on simulation using the computer code FLUKA for the beam dump and CFD-CFX for target cooling. The target has been successfully used for the production of (22)Na in a 6 day long 17 MeV, 5 μA proton irradiation run. PMID:27036769

  2. Compaction of poly(dimethylsiloxane) (PDMS) due to proton beam irradiation

    NASA Astrophysics Data System (ADS)

    Szilasi, Szabolcs Zoltan; Kokavecz, Janos; Huszank, Robert; Rajta, Istvan

    2011-03-01

    This work is about the detailed investigation of the changes of the surface topography, the degree of compaction/shrinkage and its relation to the irradiation fluence and the structure spacing in poly(dimethylsiloxane) (PDMS) patterned with 2 MeV proton microbeam. The irradiated periodic structures consisted of parallel lines with different widths and spacing. To achieve different degrees of compaction, each structure was irradiated with more different fluences. At the irradiated areas the surface topography, the adhesion, the wettability and the rigidity of the surface also changes due to the chemical/structural change of the basic poly(dimethylsiloxane) polymer. The surface topography, the phase modification of the surface, and the connection between them was revealed with using an atomic force microscope (AFM).

  3. RBE for late somatic effects in mice irradiated with 60 MeV protons relative to X-rays.

    NASA Technical Reports Server (NTRS)

    Darden, E. B., Jr.; Clapp, N. K.; Bender, R. S.; Jernigan, M. C.; Upton, A. C.

    1971-01-01

    Investigation of the relative biological effectiveness of energetic protons for the induction of somatic effects in a mammal (mice) following whole body irradiation. The proton energy used approximates the mean energy for proton spectra accompanying solar events. The effects on longevity and the incidence of major neoplastic diseases are summarized. The results obtained suggest that medium energy proton irradiation is no more effective, and on the whole, probably less effective, than conventional X radiation for the induction of late radiation effects in the mouse.

  4. The effects of oxide evolution on mechanical properties in proton- and neutron-irradiated Fe-9%Cr ODS steel

    NASA Astrophysics Data System (ADS)

    Swenson, M. J.; Dolph, C. K.; Wharry, J. P.

    2016-10-01

    The objective of this study is to evaluate the effect of irradiation on the strengthening mechanisms of a model Fe-9%Cr oxide dispersion strengthened steel. The alloy was irradiated with protons or neutrons to a dose of 3 displacements per atoms at 500 °C. Nanoindentation was used to measure strengthening due to irradiation, with neutron irradiation causing a greater increase in yield strength than proton irradiation. The irradiated microstructures were characterized using transmission electron microscopy and atom probe tomography (APT). Cluster analysis reveals solute migration from the Y-Ti-O-rich nanoclusters to the surrounding matrix after both irradiations, though the effect is more pronounced in the neutron-irradiated specimen. Because the dissolved oxygen atoms occupy interstitial sites in the iron matrix, they contribute significantly to solid solution strengthening. The dispersed barrier hardening model relates microstructure evolution to the change in yield strength, but is only accurate if solid solution contributions to strengthening are considered simultaneously.

  5. Diffusion length damage coefficient and annealing studies in proton-irradiated InP

    NASA Technical Reports Server (NTRS)

    Hakimzadeh, Roshanak; Vargas-Aburto, Carlos; Bailey, Sheila G.; Williams, Wendell

    1993-01-01

    We report on the measurement of the diffusion length damage coefficient (K(sub L)) and the annealing characteristics of the minority carrier diffusion length (L(sub n)) in Czochralski-grown zinc-doped indium phosphide (InP), with a carrier concentration of 1 x 10(exp l8) cm(exp -3). In measuring K(sub L) irradiations were made with 0.5 MeV protons with fluences ranging from 1 x 10(exp 11) to 3 x 10(exp 13) cm(exp -2). Pre- and post-irradiation electron-beam induced current (EBIC) measurements allowed for the extraction of L(sub n) from which K(sub L) was determined. In studying the annealing characteristics of L(sub n) irradiations were made with 2 MeV protons with fluence of 5 x 10(exp 13) cm(exp -2). Post-irradiation studies of L(sub n) with time at room temperature, and with minority carrier photoinjection and forward-bias injection were carried out. The results showed that recovery under Air Mass Zero (AMO) photoinjection was complete. L(sub n) was also found to recover under forward-bias injection, where recovery was found to depend on the value of the injection current. However, no recovery of L(sub n) after proton irradiation was observed with time at room temperature, in contrast to the behavior of 1 MeV electron-irradiated InP solar cells reported previously.

  6. Brainstem-sparing craniospinal irradiation delivered with pencil beam scanning proton therapy.

    PubMed

    Hill-Kayser, Christine; Kirk, Maura

    2015-04-01

    Delivery of craniospinal irradiation (CSI) is a curative approach to recurrent ependymoma, but is associated with risks from re-irradiation, particularly of the brainstem. Pencil beam scanning proton therapy allows delivery of CSI with sparing of normal tissues. Here, we describe a case of brainstem-sparing CSI that resulted in excellent coverage of the craniospinal axis with minimal radiation to brainstem. This is a novel concept that compares favorably to previously described methods using x-rays that may result in underdosing of surrounding tissues in effort to spare brainstem.

  7. Magnetism in MoS{sub 2} induced by proton irradiation

    SciTech Connect

    Mathew, S.; Gopinadhan, K.; Dhar, S.; Venkatesan, T.; Chan, T. K.; Yu, X. J.; Zhan, D.; Shen, Z. X.; Cao, L.; Rusydi, A.; Breese, M. B. H.; Thong, John T. L.

    2012-09-03

    Molybdenum disulphide, a diamagnetic layered dichalcogenide solid, is found to show magnetic ordering at room temperature when exposed to a 2 MeV proton beam. The temperature dependence of magnetization displays ferrimagnetic behavior with a Curie temperature of 895 K. A disorder mode corresponding to a zone-edge phonon and a Mo valence higher than +4 has been detected in the irradiated samples using Raman and x-ray photoelectron spectroscopy, respectively. The possible origins of long-range magnetic ordering in irradiated MoS{sub 2} samples are discussed.

  8. Brainstem-sparing craniospinal irradiation delivered with pencil beam scanning proton therapy.

    PubMed

    Hill-Kayser, Christine; Kirk, Maura

    2015-04-01

    Delivery of craniospinal irradiation (CSI) is a curative approach to recurrent ependymoma, but is associated with risks from re-irradiation, particularly of the brainstem. Pencil beam scanning proton therapy allows delivery of CSI with sparing of normal tissues. Here, we describe a case of brainstem-sparing CSI that resulted in excellent coverage of the craniospinal axis with minimal radiation to brainstem. This is a novel concept that compares favorably to previously described methods using x-rays that may result in underdosing of surrounding tissues in effort to spare brainstem. PMID:25557901

  9. Image analysis of single event transient effects on charge coupled devices irradiated by protons

    NASA Astrophysics Data System (ADS)

    Wang, Zujun; Xue, Yuanyuan; Liu, Jing; He, Baoping; Yao, Zhibin; Ma, Wuying

    2016-10-01

    The experiments of single event transient (SET) effects on charge coupled devices (CCDs) irradiated by protons are presented. The radiation experiments have been carried out at the accelerator protons with the energy of 200 MeV and 60 MeV.The incident angles of the protons are at 30°and 90° to the plane of the CCDs to obtain the images induced by the perpendicularity and incline incident angles. The experimental results show that the typical characteristics of the SET effects on a CCD induced by protons are the generation of a large number of dark signal spikes (hot pixels) which are randomly distributed in the "pepper" images. The characteristics of SET effects are investigated by observing the same imaging area at different time during proton radiation to verify the transient effects. The experiment results also show that the number of dark signal spikes increases with increasing integration time during proton radiation. The CCDs were tested at on-line and off-line to distinguish the radiation damage induced by the SET effects or DD effects. The mechanisms of the dark signal spike generation induced by the SET effects and the DD effects are demonstrated respectively.

  10. Proton Irradiation Response of CsI(Tl) Crystals for the GLAST Calorimeter

    SciTech Connect

    Bergenius, S.; Carius, S.; Carlson, P.; Grove, J.E.; Johansson, G.; Klamra, W.; Nilsson, L.; Pearce, M.; Metzler, S.D.

    2012-04-10

    The electromagnetic calorimeter of the Gamma-Ray Large Area Space Telescope (GLAST) consists of 16 towers of CsI(Tl) crystals. Each tower contains 8 layers of crystals (each 326.0 x 26.7 x 19.9 mm{sup 3}) arranged in a hodoscopic fashion. The crystals are read out at both ends with photodiodes. Crystals produced by Amcrys-H (Ukraine) are used. A full size crystal was irradiated with a 180 MeV proton beam and the radiation induced attenuation was measured. The induced radioactivity of the crystal was also studied. In this paper we will discuss the damage due to proton irradiation and compare this with the expected in-orbit background flux.

  11. Correlation of electron and proton irradiation-induced damage in InP solar cells

    NASA Technical Reports Server (NTRS)

    Walters, Robert J.; Summers, Geoffrey P.; Messenger, Scott R.; Burke, Edward A.

    1995-01-01

    When determining the best solar cell technology for a particular space flight mission, accurate prediction of solar cell performance in a space radiation environment is essential. The current methodology used to make such predictions requires extensive experimental data measured under both electron and proton irradiation. Due to the rising cost of accelerators and irradiation facilities, such extensive data sets are expensive to obtain. Moreover, with the rapid development of novel cell designs, the necessary data are often not available. Therefore, a method for predicting cell degradation based on limited data is needed. Such a method has been developed at the Naval Research Laboratory based on damage correlation using 'displacement damage dose' which is the product of the non-ionizing energy loss (NIEL) and the particle fluence. Displacement damage dose is a direct analog of the ionization dose used to correlate the effects of ionizing radiations. In this method, the performance of a solar cell in a complex radiation environment can be predicted from data on a single proton energy and two electron energies, or one proton energy, one electron energy, and Co(exp 60) gammas. This method has been used to accurately predict the extensive data set measured by Anspaugh on GaAs/Ge solar cells under a wide range of electron and proton energies. In this paper, the method is applied to InP solar cells using data measured under 1 MeV electron and 3 MeV proton irradiations, and the calculations are shown to agree well with the measured data. In addition to providing accurate damage predictions, this method also provides a basis for quantitative comparisons of the performance of different cell technologies. The performance of the present InP cells is compared to that published for GaAs/Ge cells. The results show InP to be inherently more resistant to displacement energy deposition than GaAs/Ge.

  12. Irradiation Effects of 22 and 240 MeV Protons on Several Transistors and Solar Cells

    NASA Technical Reports Server (NTRS)

    Hulten, W. C.; Honaker, W. C.; Patterson, John L.

    1961-01-01

    The work covered in this report has been directed toward the investigation of the irradiation effects of 22 and 240 MeV protons on several transistors, solar cells, resistors, and condensers to be used in the space radiation environment. The experimental data indicated definite detrimental effects on transistors and solar cells but no apparent effects on the types of resistors and condensers tested. The detrimental effects are of two distinct types: transient and permanent.

  13. InGaAs/GaAs Quantum Dots: Effects of Ensemble Interactions, Interdiffusion, Segregation and Proton Irradiation

    NASA Technical Reports Server (NTRS)

    Leon, R.

    2000-01-01

    A sumary or recent experimental findings on the effects of interdiffusion, segregation, strained ensemble interactions and proton irradiation on the optical properties of InGaAs/GaAs quantum dots (QDs) are presented.

  14. Contribution of indirect effects to clustered damage in DNA irradiated with protons.

    PubMed

    Pachnerová Brabcová, K; Štěpán, V; Karamitros, M; Karabín, M; Dostálek, P; Incerti, S; Davídková, M; Sihver, L

    2015-09-01

    Protons are the dominant particles both in galactic cosmic rays and in solar particle events and, furthermore, proton irradiation becomes increasingly used in tumour treatment. It is believed that complex DNA damage is the determining factor for the consequent cellular response to radiation. DNA plasmid pBR322 was irradiated at U120-M cyclotron with 30 MeV protons and treated with two Escherichia coli base excision repair enzymes. The yields of SSBs and DSBs were analysed using agarose gel electrophoresis. DNA has been irradiated in the presence of hydroxyl radical scavenger (coumarin-3-carboxylic acid) in order to distinguish between direct and indirect damage of the biological target. Pure scavenger solution was used as a probe for measurement of induced OH· radical yields. Experimental OH· radical yield kinetics was compared with predictions computed by two theoretical models-RADAMOL and Geant4-DNA. Both approaches use Geant4-DNA for description of physical stages of radiation action, and then each of them applies a distinct model for description of the pre-chemical and chemical stage.

  15. Radiosensitization by PARP inhibition to proton beam irradiation in cancer cells.

    PubMed

    Hirai, Takahisa; Saito, Soichiro; Fujimori, Hiroaki; Matsushita, Keiichiro; Nishio, Teiji; Okayasu, Ryuichi; Masutani, Mitsuko

    2016-09-01

    The poly(ADP-ribose) polymerase (PARP)-1 regulates DNA damage responses and promotes base excision repair. PARP inhibitors have been shown to enhance the cytotoxicity of ionizing radiation in various cancer cells and animal models. We have demonstrated that the PARP inhibitor (PARPi) AZD2281 is also an effective radiosensitizer for carbon-ion radiation; thus, we speculated that the PARPi could be applied to a wide therapeutic range of linear energy transfer (LET) radiation as a radiosensitizer. Institutes for biological experiments using proton beam are limited worldwide. This study was performed as a cooperative research at heavy ion medical accelerator in Chiba (HIMAC) in National Institute of Radiological Sciences. HIMAC can generate various ion beams; this enabled us to compare the radiosensitization effect of the PARPi on cells subjected to proton and carbon-ion beams from the same beam line. After physical optimization of proton beam irradiation, the radiosensitization effect of the PARPi was assessed in the human lung cancer cell line, A549, and the pancreatic cancer cell line, MIA PaCa-2. The effect of the PARPi, AZD2281, on radiosensitization to Bragg peak was more significant than that to entrance region. The PARPi increased the number of phosphorylated H2AX (γ-H2AX) foci and enhanced G2/M arrest after proton beam irradiation. This result supports our hypothesis that a PARPi could be applied to a wide therapeutic range of LET radiation by blocking the DNA repair response. PMID:27425251

  16. Proton or photon irradiation for hemangiomas of the choroid? A retrospective comparison

    SciTech Connect

    Hoecht, Stefan . E-mail: stefan.hoecht@charite.de; Wachtlin, Joachim; Bechrakis, Nikolaos E.; Schaefer, Christiane; Heufelder, Jens; Cordini, Dino; Kluge, Heinz; Foerster, Michael; Hinkelbein, Wolfgang

    2006-10-01

    Purpose: The aim of this study was to compare, on a retrospective basis, the results of therapy in patients with uveal hemangioma treated with photon or proton irradiation at a single center. Methods and Materials: From 1993 to 2002 a total of 44 patients were treated. Until 1998 radiotherapy was given with 6 MV photons in standard fractionation of 2.0 Gy 5 times per week. In 1998 proton therapy became available and was used since then. A dose of 20 to 22.5 Cobalt Gray Equivalent (CGE) 68 MeV protons was given on 4 consecutive days. Progressive symptoms or deterioration of vision were the indications for therapy. Results: Of the 44 patients treated, 36 had circumscribed choroidal hemangiomas and 8 had diffuse choroidal hemangiomas (DCH) and Sturge-Weber syndrome. Of the patients, 19 were treated with photons with a total dose in the range of 16 to 30 Gy. A total of 25 patients were irradiated with protons. All patients with DCH but 1 were treated with photons. Stabilization of visual acuity was achieved in 93.2% of all patients. Tumor thickness decreased in 95.4% and retinal detachment resolved in 92.9%. Late effects, although generally mild or moderate, were frequently detected. In all, 40.9% showed radiation-induced optic neuropathy, maximum Grade I. Retinopathy was found in 29.5% of cases, but only 1 patient experienced more than Grade II severity. Retinopathy and radiation-induced optic neuropathy were reversible in some of the patients and in some resolved completely. No differences could be detected between patients with circumscribed choroidal hemangiomas treated with protons and photons. Treatment was less effective in DCH patients (75%). Conclusions: Radiotherapy is effective in treating choroidal hemangiomas with respect to visual acuity and tumor thickness but a benefit of proton therapy could not be detected. Side effects are moderate but careful monitoring for side effects should be part of the follow-up procedures.

  17. Proton irradiation impacts age-driven modulations of cancer progression influenced by immune system transcriptome modifications from splenic tissue

    PubMed Central

    Wage, Justin; Ma, Lili; Peluso, Michael; Lamont, Clare; Evens, Andrew M.; Hahnfeldt, Philip; Hlatky, Lynn; Beheshti, Afshin

    2015-01-01

    Age plays a crucial role in the interplay between tumor and host, with additional impact due to irradiation. Proton irradiation of tumors induces biological modulations including inhibition of angiogenic and immune factors critical to ‘hallmark’ processes impacting tumor development. Proton irradiation has also provided promising results for proton therapy in cancer due to targeting advantages. Additionally, protons may contribute to the carcinogenesis risk from space travel (due to the high proportion of high-energy protons in space radiation). Through a systems biology approach, we investigated how host tissue (i.e. splenic tissue) of tumor-bearing mice was altered with age, with or without whole-body proton exposure. Transcriptome analysis was performed on splenic tissue from adolescent (68-day) versus old (736-day) C57BL/6 male mice injected with Lewis lung carcinoma cells with or without three fractionations of 0.5 Gy (1-GeV) proton irradiation. Global transcriptome analysis indicated that proton irradiation of adolescent hosts caused significant signaling changes within splenic tissues that support carcinogenesis within the mice, as compared with older subjects. Increases in cell cycling and immunosuppression in irradiated adolescent hosts with CDK2, MCM7, CD74 and RUVBL2 indicated these were the key genes involved in the regulatory changes in the host environment response (i.e. the spleen). Collectively, these results suggest that a significant biological component of proton irradiation is modulated by host age through promotion of carcinogenesis in adolescence and resistance to immunosuppression, carcinogenesis and genetic perturbation associated with advancing age. PMID:26253138

  18. Proton irradiation impacts age-driven modulations of cancer progression influenced by immune system transcriptome modifications from splenic tissue.

    PubMed

    Wage, Justin; Ma, Lili; Peluso, Michael; Lamont, Clare; Evens, Andrew M; Hahnfeldt, Philip; Hlatky, Lynn; Beheshti, Afshin

    2015-09-01

    Age plays a crucial role in the interplay between tumor and host, with additional impact due to irradiation. Proton irradiation of tumors induces biological modulations including inhibition of angiogenic and immune factors critical to 'hallmark' processes impacting tumor development. Proton irradiation has also provided promising results for proton therapy in cancer due to targeting advantages. Additionally, protons may contribute to the carcinogenesis risk from space travel (due to the high proportion of high-energy protons in space radiation). Through a systems biology approach, we investigated how host tissue (i.e. splenic tissue) of tumor-bearing mice was altered with age, with or without whole-body proton exposure. Transcriptome analysis was performed on splenic tissue from adolescent (68-day) versus old (736-day) C57BL/6 male mice injected with Lewis lung carcinoma cells with or without three fractionations of 0.5 Gy (1-GeV) proton irradiation. Global transcriptome analysis indicated that proton irradiation of adolescent hosts caused significant signaling changes within splenic tissues that support carcinogenesis within the mice, as compared with older subjects. Increases in cell cycling and immunosuppression in irradiated adolescent hosts with CDK2, MCM7, CD74 and RUVBL2 indicated these were the key genes involved in the regulatory changes in the host environment response (i.e. the spleen). Collectively, these results suggest that a significant biological component of proton irradiation is modulated by host age through promotion of carcinogenesis in adolescence and resistance to immunosuppression, carcinogenesis and genetic perturbation associated with advancing age.

  19. Ciliary body and choroidal melanomas treated by proton beam irradiation. Histopathologic study of eyes

    SciTech Connect

    Seddon, J.M.; Gragoudas, E.S.; Albert, D.M.

    1983-09-01

    Proton beam irradiation resulted in clinical and/or histopathological regression of large ciliary body and choroidal melanomas in three eyes. Enucleations were performed 6 1/2 weeks, five months, and 11 months after irradiation for angle-closure glaucoma from total retinal detachment, increase in retinal detachment, and neovascular glaucoma, respectively. A direct relationship was found between the length of the interval from irradiation to enucleation and the degree of histologic changes. Vascular changes in the tumors included endothelial cell swelling and decreased lumen size, basement membrane thickening, collapse of sinusoidal vessels, and thrombosis of vessels. Although apparently unaltered tumor cells remained, degenerative changes occurred in some melanoma cells, including lipid vacuoles in cytoplasm, pyknotic nuclei, and balloon cell formation. Patchy areas of necrosis and proteinaceous exudate were present. Pigment-laden macrophages were found near tumor vessels and all had a substantial chronic inflammatory infiltrate. The effect of proton beam irradiation on tumor vessels probably plays an important role in uveal melanoma regression.

  20. Initial results from a cryogenic proton irradiation of a p-channel CCD

    NASA Astrophysics Data System (ADS)

    Gow, J. P. D.; Wood, D.; Burt, D.; Hall, D. J.; Dryer, B.; Holland, A. D.; Murray, N. J.

    2015-08-01

    The displacement damage hardness that can be achieved using p-channel charge coupled devices (CCD) was originally demonstrated in 1997 and since then a number of other studies have demonstrated an improved tolerance to radiationinduced CTI when compared to n-channel CCDs. A number of recent studies have also shown that the temperature history of the device after the irradiation impacts the performance of the detector, linked to the mobility of defects at different temperatures. This study describes the initial results from an e2v technologies p-channel CCD204 irradiated at 153 K with a 10 MeV equivalent proton fluences of 1.24×109 and 1.24×1011 protons.cm-2. The number of defects identified using trap pumping, dark current and cosmetic quality immediately after irradiation and over a period of 150 hours after the irradiation with the device held at 153 K and then after different periods of time at room temperature are described. The device also exhibited a flatband voltage shift of around 30 mV per krad, determined by the reduction in full well capacity.

  1. Effects of combined irradiation of 500 keV protons and atomic oxygen on polyimide films

    NASA Astrophysics Data System (ADS)

    Novikov, Lev; Chernik, Vladimir; Zhilyakov, Lev; Voronina, Ekaterina; Chirskaia, Natalia

    2016-07-01

    Polyimide films are widely used on the spacecraft surface as thermal control coating, films in different constuctions, etc. However, the space ionizing radiation of different types can alter the mechanical, optical and electrical properties of polyimide films. For example, it is well known that 20-100 keV proton irradiation causes breaking of chemical bonds and destruction of the surface layer in polyimide, deterioration of its optical properties, etc. In low-Earth orbits serious danger for polymeric materials is atomic oxygen of the upper atmosphere of the Earth, which is the main component in the range of heights of 200-800 km. Due to the orbital spacecraft velocity, the collision energy of oxygen atoms with the surface ( 5 eV) enhances their reactivity and opens additional pathways of their reaction with near-surface layers of materials. Hyperthermal oxygen atom flow causes erosion of the polyimide surface by breaking chemical bonds and forming of volatiles products (primarily, CO and CO _{2}), which leads to mass losses and degradation of material properties. Combined effect of protons and oxygen plasma is expected to give rise to synergistic effects enhancing the destruction of polyimide surface layers. This paper describes experimental investigation of polyimide films sequential irradiation with protons and oxygen plasma. The samples were irradiated by 500 keV protons at fluences of 10 ^{14}-10 ^{16} cm ^{-2} produced with SINP cascade generator KG-500 and 5-20 eV neutral oxygen atoms at fluence of 10 ^{20} cm ^{-2} generated by SINP magnetoplasmodynamics accelerator. The proton bombardment causes the decrease in optical transmission coefficient of samples, but their transmittance recovers partially after the exposure to oxygen plasma. The results of the comparative analysis of polyimide optical transmission spectra, Raman and XPS spectra obtained at different stages of the irradiation of samples, data on mass loss of samples due to erosion of the surface are

  2. Radiation stability of ZrN under 2.6 MeV proton irradiation

    NASA Astrophysics Data System (ADS)

    Yang, Yong; Dickerson, Clayton A.; Allen, Todd R.

    2009-07-01

    Zirconium nitride is a promising alternative material for the use as an inert matrix for transuranic fuel, but the knowledge of the radiation tolerance of ZrN is very limited. We have studied the radiation stability of ZrN using a 2.6 MeV proton beam at 800 °C. The irradiated microstructure and hardening were investigated and compared with annealed samples. A high density of nano-sized defects was observed in samples irradiated to doses of 0.35 and 0.75 dpa. Some defects were identified as vacancy-type pyramidal dislocation loops using lattice resolution imaging and Fourier-filter image processing. A very slight lattice expansion was noted for the sample with a dose of 0.75 dpa. Hardening effects were found for samples irradiated to both 0.35 and 0.75 dpa using Knoop indentation.

  3. First-Principles Investigation of Electronic Excitation Dynamics in Water under Proton Irradiation

    NASA Astrophysics Data System (ADS)

    Reeves, Kyle; Kanai, Yosuke

    2015-03-01

    A predictive and quantitative understanding of electronic excitation dynamics in water under proton irradiation is of great importance in many technological areas ranging from utilizing proton beam therapy to preventing nuclear reactor damages. Despite its importance, an atomistic description of the excitation mechanism has yet to be fully understood. Identifying how a high-energy proton dissipates its kinetic energy into the electronic excitation is crucial for predicting atomistic damages, later resulting in the formation of different chemical species. In this work, we use our new, large-scale first-principles Ehrenfest dynamics method based on real-time time-dependent density functional theory to simulate the electronic response of bulk water to a fast-moving proton. In particular, we will discuss the topological nature of the electronic excitation as a function of the proton velocity. We will employ maximally-localized functions to bridge our quantitative findings from first-principles simulations to a conceptual understanding in the field of water radiolysis.

  4. Evaluation of the relative biological effectiveness of spot-scanning proton irradiation in vitro

    PubMed Central

    Maeda, Kenichiro; Yasui, Hironobu; Matsuura, Taeko; Yamamori, Tohru; Suzuki, Motofumi; Nagane, Masaki; Nam, Jin-Min; Inanami, Osamu; Shirato, Hiroki

    2016-01-01

    Variations in relative biological effectiveness (RBE) from a fixed value of 1.1 are critical in proton beam therapy. To date, studies estimating RBE at multiple positions relative to the spread-out Bragg peak (SOBP) have been predominantly performed using passive scattering methods, and limited data are available for spot-scanning beams. Thus, to investigate the RBE of spot-scanning beams, Chinese hamster fibroblast V79 cells were irradiated using the beam line at the Hokkaido University Hospital Proton Therapy Center. Cells were placed at six different depths, including the entrance of the proton beam and the proximal and distal part of the SOBP. Surviving cell fractions were analyzed using colony formation assay, and cell survival curves were obtained by the curve fitted using a linear–quadratic model. RBE10 and RBE37 were 1.15 and 1.21 at the center of the SOBP, respectively. In contrast, the distal region showed higher RBE values (1.50 for RBE10 and 1.85 for RBE37). These results are in line with those of previous studies conducted using passive scattering proton beams. Taken together, these data strongly suggest that variations in RBE should be considered during treatment planning for spot-scanning beams as well as for passive scattering proton beams. PMID:26838131

  5. Sensors for low temperature application

    DOEpatents

    Henderson, Timothy M.; Wuttke, Gilbert H.

    1977-01-01

    A method and apparatus for low temperature sensing which uses gas filled micro-size hollow glass spheres that are exposed in a confined observation area to a low temperature range (Kelvin) and observed microscopically to determine change of state, i.e., change from gaseous state of the contained gas to condensed state. By suitable indicia and classification of the spheres in the observation area, the temperature can be determined very accurately.

  6. Accelerated partial-breast irradiation using proton beams: Initial clinical experience

    SciTech Connect

    Kozak, Kevin R.; Smith, Barbara L.; Adams, Judith C.; Kornmehl, Ellen; Katz, Angela; Gadd, Michele; Specht, Michelle; Hughes, Kevin; Gioioso, Valeria; Lu, H.-M.; Braaten, Kristina; Recht, Abram; Powell, Simon N.; DeLaney, Thomas F.; Taghian, Alphonse G. . E-mail: ataghian@partners.org

    2006-11-01

    Purpose: We present our initial clinical experience with proton, three-dimensional, conformal, external beam, partial-breast irradiation (3D-CPBI). Methods and Materials: Twenty patients with Stage I breast cancer were treated with proton 3D-CPBI in a Phase I/II clinical trial. Patients were followed at 3 to 4 weeks, 6 to 8 weeks, 6 months, and every 6 months thereafter for recurrent disease, cosmetic outcome, toxicity, and patient satisfaction. Results: With a median follow-up of 12 months (range, 8-22 months), no recurrent disease has been detected. Global breast cosmesis was judged by physicians to be good or excellent in 89% and 100% of cases at 6 months and 12 months, respectively. Patients rated global breast cosmesis as good or excellent in 100% of cases at both 6 and 12 months. Proton 3D-CPBI produced significant acute skin toxicity with moderate to severe skin color changes in 79% of patients at 3 to 4 weeks and moderate to severe moist desquamation in 22% of patients at 6 to 8 weeks. Telangiectasia was noted in 3 patients. Three patients reported rib tenderness in the treated area, and one rib fracture was documented. At last follow-up, 95% of patients reported total satisfaction with proton 3D-CPBI. Conclusions: Based on our study results, proton 3D-CPBI offers good-to-excellent cosmetic outcomes in 89% to 100% of patients at 6-month and 12-month follow-up and nearly universal patient satisfaction. However, proton 3D-CPBI, as used in this study, does result in significant acute skin toxicity and may potentially be associated with late skin (telangiectasia) and rib toxicity. Because of the dosimetric advantages of proton 3D-CPBI, technique modifications are being explored to improve acute skin tolerance.

  7. Proton irradiation test to scintillator-directory-coupled CCD onboard FFAST

    NASA Astrophysics Data System (ADS)

    Nagino, Ryo; Nakajima, Hiroshi; Sadamoto, Masaaki; Sasaki, Masayuki; Tsunemi, Hiroshi; Hayashida, Kiyoshi; Anabuki, Naohisa; Kitamura, Hisashi; Uchihori, Yukio

    2013-09-01

    FFAST is a large area sky survey mission at hard X-ray region by using a spacecraft formation flying. It consists of two small satellites, a telescope satellite, carrying a multilayer super mirror, and a detector satellite, carrying scintillator-deposited CCDs (SD-CCDs). SD-CCD is the imaging device which realized sensitivity to 80 keV by pasting up a scintillator on CCD directly. Soft X-ray events are directly detected in the CCD. On the other hand, Hard X-ray events are converted to optical photons by the scintillator and then the CCD detects the photons. We have obtained the spectrum with 109Cd and successfully detected the events originated from the CsI. For a space use of a CCD, we have to understand aged deterioration of CCD in high radiative environments. In addition, in the case of SD-CCD, we must investigate the influence of radio-activation of a scintillator. We performed experiments of proton irradiation to the SD-CCD as space environmental tests of cosmic rays. The SD-CCD is irradiated with the protons with the energy of 100 MeV and neglected for about 150 hours. As a result, the derived CTI profile of SD-CCD is similarly to ones of XIS/Suzaku and NeXT4 CCD/ASTRO-H. In contrast, CTIs derived from the data within 4 hours after irradiation is 10 times or more larger than the ones after 150 hours. This may be due to influence of an annealing. We also report a performance study of SD-CCD, including the detection of scintillation events, before proton irradiation.

  8. Degradation modeling of InGaP/GaAs/Ge triple-junction solar cells irradiated by protons

    NASA Astrophysics Data System (ADS)

    Maximenko, S. I.; Lumb, M. P.; Messenger, S. R.; Hoheisel, R.; Affouda, C.; Scheiman, D.; Gonzalez, M.; Lorentzen, J.; Jenkins, P. P.; Walters, R. J.

    2014-03-01

    Experimental results on triple-junction solar cells irradiated by 3 MeV proton irradiation to very high damage levels are presented. The minority carrier transport properties were obtained through quantum efficiency and EBIC measurements and an analytical drift-diffusion solver was used in understanding the results for different degradation levels where multiple damage mechanisms are evident.

  9. Response of thyroid follicular cells to gamma irradiation compared to proton irradiation. I. Initial characterization of DNA damage, micronucleus formation, apoptosis, cell survival, and cell cycle phase redistribution

    NASA Technical Reports Server (NTRS)

    Green, L. M.; Murray, D. K.; Bant, A. M.; Kazarians, G.; Moyers, M. F.; Nelson, G. A.; Tran, D. T.

    2001-01-01

    The RBE of protons has been assumed to be equivalent to that of photons. The objective of this study was to determine whether radiation-induced DNA and chromosome damage, apoptosis, cell killing and cell cycling in organized epithelial cells was influenced by radiation quality. Thyroid-stimulating hormone-dependent Fischer rat thyroid cells, established as follicles, were exposed to gamma rays or proton beams delivered acutely over a range of physical doses. Gamma-irradiated cells were able to repair DNA damage relatively rapidly so that by 1 h postirradiation they had approximately 20% fewer exposed 3' ends than their counterparts that had been irradiated with proton beams. The persistence of free ends of DNA in the samples irradiated with the proton beam implies that either more initial breaks or a quantitatively different type of damage had occurred. These results were further supported by an increased frequency of chromosomal damage as measured by the presence of micronuclei. Proton-beam irradiation induced micronuclei at a rate of 2.4% per gray, which at 12 Gy translated to 40% more micronuclei than in comparable gamma-irradiated cultures. The higher rate of micronucleus formation and the presence of larger micronuclei in proton-irradiated cells was further evidence that a qualitatively more severe class of damage had been induced than was induced by gamma rays. Differences in the type of damage produced were detected in the apoptosis assay, wherein a significant lag in the induction of apoptosis occurred after gamma irradiation that did not occur with protons. The more immediate expression of apoptotic cells in the cultures irradiated with the proton beam suggests that the damage inflicted was more severe. Alternatively, the cell cycle checkpoint mechanisms required for recovery from such damage might not have been invoked. Differences based on radiation quality were also evident in the alpha components of cell survival curves (0.05 Gy(-1) for gamma rays, 0

  10. Effects of a granulocyte colony stimulating factor, Neulasta, in mini pigs exposed to total body proton irradiation

    NASA Astrophysics Data System (ADS)

    Sanzari, Jenine K.; Krigsfeld, Gabriel S.; Shuman, Anne L.; Diener, Antonia K.; Lin, Liyong; Mai, Wilfried; Kennedy, Ann R.

    2015-04-01

    Astronauts could be exposed to solar particle event (SPE) radiation, which is comprised mostly of proton radiation. Proton radiation is also a treatment option for certain cancers. Both astronauts and clinical patients exposed to ionizing radiation are at risk for loss of white blood cells (WBCs), which are the body's main defense against infection. In this report, the effect of Neulasta treatment, a granulocyte colony stimulating factor, after proton radiation exposure is discussed. Mini pigs exposed to total body proton irradiation at a dose of 2 Gy received 4 treatments of either Neulasta or saline injections. Peripheral blood cell counts and thromboelastography parameters were recorded up to 30 days post-irradiation. Neulasta significantly improved WBC loss, specifically neutrophils, in irradiated animals by approximately 60% three days after the first injection, compared to the saline treated, irradiated animals. Blood cell counts quickly decreased after the last Neulasta injection, suggesting a transient effect on WBC stimulation. Statistically significant changes in hemostasis parameters were observed after proton radiation exposure in both the saline and Neulasta treated irradiated groups, as well as internal organ complications such as pulmonary changes. In conclusion, Neulasta treatment temporarily alleviates proton radiation-induced WBC loss, but has no effect on altered hemostatic responses.

  11. Effects of a granulocyte colony stimulating factor, Neulasta, in mini pigs exposed to total body proton irradiation

    PubMed Central

    Sanzari, Jenine K.; Krigsfeld, Gabriel S.; Shuman, Anne L.; Diener, Antonia K.; Lin, Liyong; Mai, Wilfried; Kennedy, Ann R.

    2015-01-01

    Astronauts could be exposed to solar particle event (SPE) radiation, which is comprised mostly of proton radiation. Proton radiation is also a treatment option for certain cancers. Both astronauts and clinical patients exposed to ionizing radiation are at risk for white blood cell (WBC) loss, which are the body’s main defense against infection. In this report, the effect of Neulasta treatment, a granulocyte colony stimulating factor, after proton radiation exposure is discussed. Mini pigs exposed to total body proton irradiation at a dose of 2 Gy received 4 treatments of either Neulasta or saline injections. Peripheral blood cell counts and thromboelastography parameters were recorded up to 30 days post-irradiation. Neulasta significantly improved white blood cell (WBC), specifically neutrophil, loss in irradiated animals by approximately 60% three days after the first injection, compared to the saline treated irradiated animals. Blood cell counts quickly decreased after the last Neulasta injection, suggesting a transient effect on WBC stimulation. Statistically significant changes in hemostasis parameters were observed after proton radiation exposure in both the saline and Neulasta treated irradiated groups, as well internal organ complications such as pulmonary changes. In conclusion, Neulasta treatment temporarily alleviates proton radiation-induced WBC loss, but has no effect on altered hemostatic responses. PMID:25909052

  12. Neutron and Proton Radiation Damage and Isothermal Annealing of Irradiated SiC Schottky Power Diodes

    SciTech Connect

    Kulisek, Jonathan A.; Blue, Thomas E.

    2009-03-16

    NASA is exploring the potential use of nuclear reactors as power sources for future missions. These missions will require semiconductor switches to be placed in close vicinity to the reactor, in the midst of a high neutron and gamma radiation field. Cree SiC Schottky diodes, part number CSD10120A, rated at 10 A and 1200 V, were chosen as the test articles for this radiation-hardness study, since SiC is a wide bandgap semiconductor that has exhibited tolerance for such high radiation environments. As an extension of previous work regarding the degradation of SiC Schottky diodes in the presence of a neutron and gamma radiation field, isothermal annealing experiments were performed on these diodes after they were irradiated in The Ohio State University Research Reactor (OSURR). The experimental results demonstrate that even at an anneal temperature of only 175 C, a noticeable improvement in the electrical performance of the diodes, in the form of decreased series resistance, may be readily observed from I-V curve measurements. Also, since electrical components used for space applications will also be exposed to charged particle radiation from space, such as high energy protons in the Van Allen Radiation Belts surrounding earth, it is important that, in studying the effects of radiation-induced displacement damage, the effects of both neutron and charged particle radiation are considered. Therefore, the data obtained from this study were compared with the data obtained from previous 203 MeV proton irradiations, for which the same diode model was tested. To develop neutron-proton equivalencies which are relevant to the radiation electronics hardening community and the materials science community, comparisons of the degradation of the diodes for proton and neutron irradiation are made in two ways 1) on the basis of displacement damage dose, D{sub d} for protons and neutrons; and 2) on the basis of initially induced vacancies per atom (at a temperature of 0 K)(IIVPA0) for

  13. Spatial resolution and nature of defects produced by low-energy proton irradiation of GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Kachare, R.; Anspaugh, B. E.

    1986-01-01

    AlGaAs/GaAs solar cells with about 0.5-micron-thick Al(0.85)Ga(0.15)As window layers were irradiated using isotropic and normal incidence protons having energies between 50 and 500 keV with fluences up to 1 x 10 to the 12th protons/sq cm. Although the projected range for these protons varies from 0 to more than 4.5 microns, the recombination losses due to the irradiation-induced defects were observed to be maximum in the vicinity of the AlGaAs/GaAs interface and the space-charge region irrespective of the proton energy. This was found by analyzing spectral response measurements. The results are explained by using a model in which the interaction of as-grown dislocations with irradiation-induced point defects is considered.

  14. Strong hole-doping and robust resistance-decrease in proton-irradiated graphene

    PubMed Central

    Lee, Chul; Kim, Jiho; Kim, SangJin; Chang, Young Jun; Kim, Keun Soo; Hong, ByungHee; Choi, E. J.

    2016-01-01

    Great effort has been devoted in recent years to improve the electrical conductivity of graphene for use in practical applications. Here, we demonstrate the hole carrier density of CVD graphene on a SiO2/Si substrate increases by more than one order of magnitude to n = 3 × 1013 cm−2 after irradiation with a high energy 5 MeV proton beam. As a result, the dc-resistance (R) of graphene is reduced significantly by 60%. Only a negligible amount of defect is created by the irradiation. Also the hole-doped low resistance state of graphene remains robust against external perturbations. This carrier doping is achieved without requiring the bias-gate voltage as is the case for other field effect devices. We make two important observations, (i) occurrence of the doping after the irradiation is turned off (ii) indispensability of the SiO2-layer in the substrate, which leads to a purely electronic mechanism for the doping where electron-hole pair creation and interlayer Coulomb attraction play a major role. A flux-dependent study predicts that an ultrahigh doping may be obtained by longer irradiation. We expect the irradiation doping method could be applied to other atomically thin solids, facilitating the fundamental study and application of the 2d materials. PMID:26888197

  15. Chromothripsis-like chromosomal rearrangements induced by ionizing radiation using proton microbeam irradiation system

    PubMed Central

    Morishita, Maki; Muramatsu, Tomoki; Suto, Yumiko; Hirai, Momoki; Konishi, Teruaki; Hayashi, Shin; Shigemizu, Daichi; Tsunoda, Tatsuhiko; Moriyama, Keiji; Inazawa, Johji

    2016-01-01

    Chromothripsis is the massive but highly localized chromosomal rearrangement in response to a one-step catastrophic event, rather than an accumulation of a series of subsequent and random alterations. Chromothripsis occurs commonly in various human cancers and is thought to be associated with increased malignancy and carcinogenesis. However, the causes and consequences of chromothripsis remain unclear. Therefore, to identify the mechanism underlying the generation of chromothripsis, we investigated whether chromothripsis could be artificially induced by ionizing radiation. We first elicited DNA double-strand breaks in an oral squamous cell carcinoma cell line HOC313-P and its highly metastatic subline HOC313-LM, using Single Particle Irradiation system to Cell (SPICE), a focused vertical microbeam system designed to irradiate a spot within the nuclei of adhesive cells, and then established irradiated monoclonal sublines from them, respectively. SNP array analysis detected a number of chromosomal copy number alterations (CNAs) in these sublines, and one HOC313-LM-derived monoclonal subline irradiated with 200 protons by the microbeam displayed multiple CNAs involved locally in chromosome 7. Multi-color FISH showed a complex translocation of chromosome 7 involving chromosomes 11 and 12. Furthermore, whole genome sequencing analysis revealed multiple de novo complex chromosomal rearrangements localized in chromosomes 2, 5, 7, and 20, resembling chromothripsis. These findings suggested that localized ionizing irradiation within the nucleus may induce chromothripsis-like complex chromosomal alterations via local DNA damage in the nucleus. PMID:26862731

  16. Chromothripsis-like chromosomal rearrangements induced by ionizing radiation using proton microbeam irradiation system.

    PubMed

    Morishita, Maki; Muramatsu, Tomoki; Suto, Yumiko; Hirai, Momoki; Konishi, Teruaki; Hayashi, Shin; Shigemizu, Daichi; Tsunoda, Tatsuhiko; Moriyama, Keiji; Inazawa, Johji

    2016-03-01

    Chromothripsis is the massive but highly localized chromosomal rearrangement in response to a one-step catastrophic event, rather than an accumulation of a series of subsequent and random alterations. Chromothripsis occurs commonly in various human cancers and is thought to be associated with increased malignancy and carcinogenesis. However, the causes and consequences of chromothripsis remain unclear. Therefore, to identify the mechanism underlying the generation of chromothripsis, we investigated whether chromothripsis could be artificially induced by ionizing radiation. We first elicited DNA double-strand breaks in an oral squamous cell carcinoma cell line HOC313-P and its highly metastatic subline HOC313-LM, using Single Particle Irradiation system to Cell (SPICE), a focused vertical microbeam system designed to irradiate a spot within the nuclei of adhesive cells, and then established irradiated monoclonal sublines from them, respectively. SNP array analysis detected a number of chromosomal copy number alterations (CNAs) in these sublines, and one HOC313-LM-derived monoclonal subline irradiated with 200 protons by the microbeam displayed multiple CNAs involved locally in chromosome 7. Multi-color FISH showed a complex translocation of chromosome 7 involving chromosomes 11 and 12. Furthermore, whole genome sequencing analysis revealed multiple de novo complex chromosomal rearrangements localized in chromosomes 2, 5, 7, and 20, resembling chromothripsis. These findings suggested that localized ionizing irradiation within the nucleus may induce chromothripsis-like complex chromosomal alterations via local DNA damage in the nucleus. PMID:26862731

  17. Late cataractogenesis in rhesus monkeys irradiated with protons and radiogenic cataract in other species

    SciTech Connect

    Lett, J.T.; Lee, A.C.; Cox, A.B. )

    1991-05-01

    Rhesus monkeys (Macaca mulatta) which were irradiated at ca. 2 years of age with acute doses (less than or equal to 5 Gy) of protons (32-2300 MeV) are exhibiting the late progressive phase of radiation cataractogenesis 20-24 years after exposure, the period during which we have been monitoring the sequelae of irradiation of the lens. The median life span of the primate is approximately 24 years. Analogous late ocular changes also occur in a similar period of the lifetimes of New Zealand White (NZW) rabbits (Oryctolagus cuniculus) exposed at 8-10 weeks of age to 460-MeV {sup 56}Fe ions. In this experiment, which has been in progress for ca. 6 years, we are following the development of radiation-induced lenticular opacification (cataractogenic profiles) throughout the life span. The median life span of the lagomorph is 5-7 years. Cataractogenic profiles for NZW rabbits irradiated with {sup 20}Ne and {sup 40}Ar ions and {sup 60}Co gamma photons were obtained previously. Reference is also made to measurements of the cataractogenic profiles of a short-lived rodent, the Fischer 344 rat (Rattus norvegicus) during the first year after exposure at 8-10 weeks of age to spread-Bragg-peak protons of 55 MeV nominal energy. The median life span of the rodent is reported to be 2-3 years.

  18. Electrical properties of as-grown and proton-irradiated high purity silicon

    NASA Astrophysics Data System (ADS)

    Krupka, Jerzy; Karcz, Waldemar; Kamiński, Paweł; Jensen, Leif

    2016-08-01

    The complex permittivity of as-grown and proton-irradiated samples of high purity silicon obtained by the floating zone method was measured as a function of temperature at a few frequencies in microwave spectrum by employing the quasi TE011 and whispering gallery modes excited in the samples under test. The resistivity of the samples was determined from the measured imaginary part of the permittivity. The resistivity was additionally measured at RF frequencies employing capacitive spectroscopy as well as in a standard direct current experiment. The sample of as-grown material had the resistivity of ∼85 kΩ cm at room temperature. The sample irradiated with 23-MeV protons had the resistivity of ∼500 kΩ cm at 295 K and its behavior was typical of the intrinsic material at room and at elevated temperatures. For the irradiated sample, the extrinsic conductivity region is missing and at temperatures below 250 K hopping conductivity occurs. Thermal cycle hysteresis of the resistivity for the sample of as-grown material is observed. After heating and subsequent cooling of the sample, its resistivity decreases and then slowly (∼50 h) returns to the initial value.

  19. The risk of enucleation after proton beam irradiation of uveal melanoma

    SciTech Connect

    Egan, K.M.; Gragoudas, E.S.; Seddon, J.M.; Glynn, R.J.; Munzenreider, J.E.; Goitein, M.; Verhey, L.; Urie, M.; Koehler, A. )

    1989-09-01

    Enucleation after proton beam irradiation of uveal melanomas occurred in 64 (6.4%) of 994 eyes with a median follow-up time of 2.7 years. The median time between irradiation and enucleation in the 64 enucleated eyes was 13 months. The probability of retaining the eye was 95 and 90%, 2 and 5 years postirradiation, respectively. Three percent of eyes were enucleated during posttreatment year 1, and the yearly rate was 1% by the fourth year. No patient had enucleation later than 5 1/2 years posttreatment. The complication most likely to result in enucleation was neovascular glaucoma although this was frequently managed without enucleation. Other common reasons for enucleation were documented or suspected tumor growth and complete retinal detachment with associated loss of vision. The leading risk factors for enucleation were anterior tumor margin involving the ciliary body, tumor height greater than 8 mm, and proximity of the tumor to the fovea. Based on the presence or absence of these factors, 5-year eye retention rates were 99, 92, and 76% for low-, moderate-, and high-risk groups, respectively. Thus, the probability of eye retention after proton beam irradiation is high even among those at greatest risk of enucleation.

  20. Effect of front and rear incident proton irradiation on silicon solar cells

    NASA Technical Reports Server (NTRS)

    Anspaugh, Bruce; Kachare, Ram

    1987-01-01

    Four solar cell types of current manufacture were irradiated through the front and rear surfaces with protons in the energy range between 1 and 10 MeV. The solar cell parameters varied for this study were cell thickness and back surface field (BSF) vs. no BSF. Some cells were irradiated at normal incidence and an equal number were irradiated with simulated isotropic fluences. The solar cell electrical characteristics were measured under simulated AM0 illumination after each fluence. Using the normal incidence data, proton damage coefficients were computed for all four types of cells for both normal and omnidirectional radiation fields. These were found to compare well with the omnidirectional damage coefficients derived directly from the rear-incidence radiation data. Similarly, the rear-incidence omnidirectional radiation data were used to compute appropriate damage coefficients. A method for calculating the effect of a spectrum of energies is derived from these calculations. It is suitable for calculating the degradation of cells in space when they have minimal rear-surface shielding.

  1. Correlation of radiation-induced changes in mechanical properties and microstructural development of Alloy 718 irradiated with mixed spectra of high-energy protons and spallation neutrons

    NASA Astrophysics Data System (ADS)

    Sencer, B. H.; Bond, G. M.; Garner, F. A.; Hamilton, M. L.; Maloy, S. A.; Sommer, W. F.

    2001-07-01

    Alloy 718 is a γ '(Ni 3(Al,Ti))-γ″(Ni 3Nb) hardenable superalloy with attractive strength, and corrosion resistance. This alloy is a candidate material for use in accelerator production of tritium (APT) target and blanket applications, where it would have to withstand low-temperature irradiation by high-energy protons and spallation neutrons. The existing data base, relevant to such irradiation conditions, is very limited. Alloy 718 has therefore been exposed to a particle flux and spectrum at the Los Alamos Neutron Science Center (LANSCE), closely matching those expected in the APT target and blanket applications. The yield stress of Alloy 718 increases with increasing dose up to ˜0.5 dpa, and then decreases with further increase in dose. The uniform elongation, however, drastically decreases with increasing dose at very low doses (<0.5 dpa), and does not recover when the alloy later softens somewhat. Transmission electron microscopy (TEM) investigation of Alloy 718 shows that superlattice spots corresponding to the age-hardening precipitate phases γ ' and γ″ are lost from the diffraction patterns for Alloy 718 by only 0.6 dpa, the lowest proton-induced dose level achieved in this experiment. Examination of samples that were neutron irradiated to doses of only ˜0.1 dpa showed that precipitates are faintly visible in diffraction patterns but are rapidly becoming invisible. It is proposed that the γ ' and γ″ first become disordered (by <0.6 dpa), but remain as solute-rich aggregates that still contribute to the hardness at relatively low dpa levels, and then are gradually dispersed at higher doses.

  2. Proton and photon absorbed-dose conversion coefficients for embryo and foetus from top-down irradiation geometry.

    PubMed

    Chen, Jing

    2007-01-01

    Absorbed-dose conversion coefficients are calculated for the embryo of 8 weeks and the foetus of 3, 6 or 9 months when the mother's body is exposed to protons and photons from top-down (TOP) direction. It provides data sets in addition to other standard irradiation geometries published previously. The TOP-irradiation geometry is considered here, because high-energy particles are often peaked from the TOP direction onboard aircrafts. The results show that absorbed-doses from high-energy particles could be underestimated significantly if isotropic (ISO) irradiation geometry is assumed. For protons of 100 GeV, absorbed-doses from TOP irradiation are approximately 2.3-2.9 times higher than the doses from ISO irradiation for different foetal ages. For 10 GeV photons, foetal doses from TOP irradiation are approximately 6.8-12 times higher than the doses from ISO irradiation. The coefficients from TOP-irradiation geometry are given in wide energy ranges, from 100 MeV to 100 GeV for protons and from 50 keV to 10 GeV for photons. They can, therefore, be used in various applications whenever exposure from the TOP-irradiation direction is concerned.

  3. Development of a PET cyclotron based irradiation setup for proton radiobiology

    NASA Astrophysics Data System (ADS)

    Ghithan, Sharif; Crespo, Paulo; do Carmo, S. J. C.; Ferreira Marques, Rui; Fraga, F. A. F.; Simões, Hugo; Alves, Francisco; Rachinhas, P. J. B. M.

    2015-02-01

    An out-of-yoke irradiation setup using the proton beam from a cyclotron that ordinary produces radioisotopes for positron emission tomography (PET) has been developed, characterized, calibrated and validated. The current from a 20 μm thick aluminum transmission foil is readout by home-made transimpedance electronics, providing online dose information. The main monitoring variables, delivered in real-time, include beam current, integrated charge and dose rate. Hence the dose and integrated current delivered at a given instant to an experimental setup can be computer-controlled with a shutter. In this work, we report on experimental results and Geant4 simulations of a setup which exploits for the first time the 18 MeV proton beam from a PET cyclotron to irradiate a selected region of a target using the developed irradiation system. By using this system, we are able to deliver a homogeneous beam on targets with 18 mm diameter, allowing to achieve the controlled irradiation of cell cultures located in biological multi-well dishes of 16 mm diameter. We found that the magnetic field applied inside the cyclotron plays a major role for achieving the referred to homogeneity. The quasi-Gaussian curve obtained by scanning the magnet current and measuring the corresponding dose rate must be measured before any irradiation procedure, with the shutter closed. At the optimum magnet current, which corresponds to the center of the Gaussian, a homogenous dose is observed over the whole target area. Making use of a rotating disk with a slit of 0.5 mm at a radius of 150 mm, we could measure dose rates on target ranging from 500 mGy/s down to 5 mGy/s. For validating the developed irradiation setup, several Gafchromic® EBT2 films were exposed to different values of dose. The absolute dose in the irradiated films were assessed in the 2D film dosimetry system of the Department of Radiotherapy of Coimbra University Hospital Center with a precision better than 2%. In the future, we plan

  4. Proton irradiation effects on advanced digital and microwave III-V components

    NASA Astrophysics Data System (ADS)

    Hash, G. L.; Schwank, J. R.; Shaneyfelt, M. R.; Sandoval, C. E.; Connors, M. P.; Sheridan, T. J.; Sexton, F. W.; Slayton, E. M.; Heise, J. A.; Foster, C.

    1994-01-01

    A wide range of advanced III-V components suitable for use in high-speed satellite communication systems were evaluated for displacement damage and single-event effects in high-energy, high-fluence proton environments. Transistors and integrated circuits (both digital and MMIC) were irradiated with protons at energies from 41 to 197 MeV and at fluences from 10(exp 10) to 2 x 10(exp 14) protons/sq cm. Large soft-error rates were measured for digital GaAs MESFET (3 x 10(exp -5) errors/bit-day) and heterojunction bipolar circuits (10(exp -5) errors/bit-day). No transient signals were detected from MMIC circuits. The largest degradation in transistor response caused by displacement damage was observed for 1.0-(mu)m depletion- and enhancement-mode MESFET transistors. Shorter gate length MESFET transistors and HEMT transistors exhibited less displacement-induced damage. These results show that memory-intensive GaAs digital circuits may result in significant system degradation due to single-event upset in natural and man-made space environments. However, displacement damage effects should not be a limiting factor for fluence levels up to 10(exp 14) protons/sq cm (equivalent to total doses in excess of 10 Mrad(GaAs)).

  5. Early irradiation of matter in the solar system: magnesium (proton, neutron) scheme.

    PubMed

    Heymann, D; Dziczkaniec, M

    1976-01-01

    The occurrence of positive and negative (26)Mg anomalies in inclusions of the Allende meteorite is explained in terms of proton bombardment of a gas of solar composition. A significant fraction of (26)Mg in the irradiated gas is stored temporarily in the form of radioactive (26)Al by the reaction (26)Mg(p,n) (26)Al. Proton fluxes of 10(17) to 10(19) protons per square centimeter per year at l million electron volts are inferred. Aluminum-rich materials condensing from the gas phase have positive (26)Mg anomalies, whereas magnesium-rich materials have negative (26)Mg anomalies. The proton flux required to account for the observed magnesium anomalies is used to investigate possible isotopic anomalies in the elements from oxygen to argon. Detectable isotopic anomalies are predicted only for neon. The anomalous neon is virtually pure (22)Ne from (22)Na decay. The predicted amount of anomalous (22)Ne is about 10(-8) cubic centimeter (at standard temperature and pressure) per milligram of sodium.

  6. Early irradiation of matter in the solar system - Magnesium /proton, neutron/ scheme

    NASA Technical Reports Server (NTRS)

    Heymann, D.; Dziczkaniec, M.

    1976-01-01

    The occurrence of positive and negative Mg-26 anomalies in inclusions of the Allende meteorite is explained in terms of proton bombardment of a gas of solar composition. A significant fraction of Mg-26 in the irradiated gas is stored temporarily in the form of radioactive Al-26 by the reaction Mg-26(p, n)Al-26. Proton fluxes of 10 to the 17th power to 10 to the 19th power protons per square centimeter per year at 1 million electron volts are inferred. Aluminum-rich materials condensing from the gas phase have positive Mg-26 anomalies, whereas magnesium-rich materials have negative Mg-26 anomalies. The proton flux required to account for the observed magnesium anomalies is used to investigate possible isotopic anomalies in the elements from oxygen to argon. Detectable isotopic anomalies are predicted only for neon. The anomalous neon is virtually pure Ne-22 from Na-22 decay. The predicted amount of anomalous Ne-22 is about 10 to the -8th power cubic centimeter (at standard temperature and pressure) per milligram of sodium.

  7. Proton irradiation effects on advanced digital and microwave III-V components

    SciTech Connect

    Hash, G.L.; Schwank, J.R.; Shaneyfelt, M.R.; Sandoval, C.E.; Connors, M.P.; Sheridan, T.J.; Sexton, F.W.; Slayton, E.M.; Heise, J.A.; Foster, C.

    1994-09-01

    A wide range of advanced III-V components suitable for use in high-speed satellite communication systems were evaluated for displacement damage and single-event effects in high-energy, high-fluence proton environments. Transistors and integrated circuits (both digital and MMIC) were irradiated with protons at energies from 41 to 197 MeV and at fluences from 10{sup 10} to 2 {times} 10{sup 14} protons/cm{sup 2}. Large soft-error rates were measured for digital GaAs MESFET (3 {times} 10{sup {minus}5} errors/bit-day) and heterojunction bipolar circuits (10{sup {minus}5} errors/bit-day). No transient signals were detected from MMIC circuits. The largest degradation in transistor response caused by displacement damage was observed for 1.0-{mu}m depletion- and enhancement-mode MESFET transistors. Shorter gate length MESFET transistors and HEMT transistors exhibited less displacement-induced damage. These results show that memory-intensive GaAs digital circuits may result in significant system degradation due to single-event upset in natural and man-made space environments. However, displacement damage effects should not be a limiting factor for fluence levels up to 10{sup 14} protons/cm{sup 2} [equivalent to total doses in excess of 10 Mrad(GaAs)].

  8. LET-dependent radiosensitization effects of gold nanoparticles for proton irradiation

    NASA Astrophysics Data System (ADS)

    Li, Sha; Penninckx, Sébastien; Karmani, Linda; Heuskin, Anne-Catherine; Watillon, Kassandra; Marega, Riccardo; Zola, Jerome; Corvaglia, Valentina; Genard, Geraldine; Gallez, Bernard; Feron, Olivier; Martinive, Philippe; Bonifazi, Davide; Michiels, Carine; Lucas, Stéphane

    2016-11-01

    The development of new modalities and protocols is of major interest to improve the outcome of cancer treatment. Given the appealing physical properties of protons and the emerging evidence of biological relevance of the use of gold nanoparticles (GNPs), the radiosensitization effects of GNPs (5 or 10 nm) have been investigated in vitro in combination with a proton beam of different linear energy transfer (LET). After the incubation with GNPs for 24 h, nanoparticles were observed in the cytoplasm of A431 cells exposed to 10 nm GNPs, and in the cytoplasm as well as the nucleus of cells exposed to 5 nm GNPs. Cell uptake of 0.05 mg ml‑1 of GNPs led to 0.78 pg Au/cell and 0.30 pg Au/cell after 24 h incubation for 10 and 5 nm GNPs respectively. A marked radiosensitization effect of GNPs was observed with 25 keV μm‑1 protons, but not with 10 keV μm‑1 protons. This effect was more pronounced for 10 nm GNPs than for 5 nm GNPs. By using a radical scavenger, a major role of reactive oxygen species in the amplification of the death of irradiated cell was identified. All together, these results open up novel perspectives for using high-Z metallic NPs in protontherapy.

  9. Proton acceleration by irradiation of isolated spheres with an intense laser pulse

    NASA Astrophysics Data System (ADS)

    Ostermayr, T. M.; Haffa, D.; Hilz, P.; Pauw, V.; Allinger, K.; Bamberg, K.-U.; Böhl, P.; Bömer, C.; Bolton, P. R.; Deutschmann, F.; Ditmire, T.; Donovan, M. E.; Dyer, G.; Gaul, E.; Gordon, J.; Hegelich, B. M.; Kiefer, D.; Klier, C.; Kreuzer, C.; Martinez, M.; McCary, E.; Meadows, A. R.; Moschüring, N.; Rösch, T.; Ruhl, H.; Spinks, M.; Wagner, C.; Schreiber, J.

    2016-09-01

    We report on experiments irradiating isolated plastic spheres with a peak laser intensity of 2 -3 ×1020Wcm -2 . With a laser focal spot size of 10 μ m full width half maximum (FWHM) the sphere diameter was varied between 520 nm and 19.3 μ m . Maximum proton energies of ˜25 MeV are achieved for targets matching the focal spot size of 10 μ m in diameter or being slightly smaller. For smaller spheres the kinetic energy distributions of protons become nonmonotonic, indicating a change in the accelerating mechanism from ambipolar expansion towards a regime dominated by effects caused by Coulomb repulsion of ions. The energy conversion efficiency from laser energy to proton kinetic energy is optimized when the target diameter matches the laser focal spot size with efficiencies reaching the percent level. The change of proton acceleration efficiency with target size can be attributed to the reduced cross-sectional overlap of subfocus targets with the laser. Reported experimental observations are in line with 3D3V particle in cell simulations. They make use of well-defined targets and point out pathways for future applications and experiments.

  10. Acute effects of whole-body proton irradiation on the immune system of the mouse

    NASA Technical Reports Server (NTRS)

    Kajioka, E. H.; Andres, M. L.; Li, J.; Mao, X. W.; Moyers, M. F.; Nelson, G. A.; Slater, J. M.; Gridley, D. S.

    2000-01-01

    The acute effects of proton whole-body irradiation on the distribution and function of leukocyte populations in the spleen and blood were examined and compared to the effects of photons derived from a (60)Co gamma-ray source. Adult female C57BL/6 mice were exposed to a single dose (3 Gy at 0.4 Gy/min) of protons at spread-out Bragg peak (SOBP), protons at the distal entry (E) region, or gamma rays and killed humanely at six different times thereafter. Specific differences were noted in the results, thereby suggesting that the kinetics of the response may be variable. However, the lack of significant differences in most assays at most times suggests that the RBE for both entry and peak regions of the Bragg curve was essentially 1.0 under the conditions of this study. The greatest immunodepression was observed at 4 days postexposure. Flow cytometry and mitogenic stimulation analyses of the spleen and peripheral blood demonstrated that lymphocyte populations differ in radiosensitivity, with B (CD19(+)) cells being most sensitive, T (CD3(+)) cells being moderately sensitive, and natural killer (NK1.1(+)) cells being most resistant. B lymphocytes showed the most rapid recovery. Comparison of the T-lymphocyte subsets showed that CD4(+) T helper/inducer cells were more radiosensitive than the CD8(+) T cytotoxic/suppressor cells. These findings should have an impact on future studies designed to maximize protection of normal tissue during and after proton-radiation exposure.

  11. Subcritical power reactor with irradiation by a beam of accelerated protons

    SciTech Connect

    Ado, Yu.M.; Kryuchkov, V.P.; Lebedev, V.N.

    1995-04-01

    The physical and economic aspects of constructing a reactivity accident-free nuclear reactor are discussed. The approach described is based on uranium fission in a deeply subcritical reactor in which the chain reaction is initiated by an external source of neutrons, thus eliminating runaway. Protons are assumed to be the primary particles because the accelerator technology is best developed for this method of irradiation. A subcritical reactor and a high-power proton accelerator is determined to be sound in principle, and has the advantages of eliminating runaway accidents, decreasing fuel costs, higher efficiency due to increased intervals between fuel loadings, and controlling the reactor power and shielding by changing the beam current of the accelerator. 29 refs., 8 figs., 2 tabs.

  12. Delayed effects of proton irradiation in Macaca Mulatta (22-year summary)

    SciTech Connect

    Woods, D.H.; Hardy, K.A.; Cox, A.B.; Salmon, Y.L.; Yochmowitz, M.G.; Cordts, R.E. )

    1989-05-15

    Lifetime observations on a group of rhesus monkeys indicate that life expectancy loss from exposure to protons in the energy range encountered in the Van Allen belts and solar proton events can be correlated with the dose and energy of radiation. The primary cause of life shortening is nonleukemic cancers. Radiation also increased the rise of endometriosis (an abnormal proliferation of the lining of the uterus in females). Other effects associated with radiation exposures are lowered glucose tolerance and increased incidence of cataracts. Calculations of the relative risk of fatal cancers in the irradiated subjects reveal that the total body surface dose required to double the risk of death from cancer over a 20-year post exposure period varies with the linear energy transfer (LET) of the radiation. The ability to determine the integrated dose and LET spectrum in space radiation exposures of humans is, therefore, critical to the assessment of lifetime cancer risk.

  13. Delayed effects of proton irradiation in Macaca Mulatta (22-year summary)

    NASA Astrophysics Data System (ADS)

    Woods, D. H.; Hardy, K. A.; Cox, A. B.; Salmon, Y. L.; Yochmowitz, M. G.; Cordts, R. E.

    1989-05-01

    Lifetime observations on a group of rhesus monkeys indicate that life expectancy loss from exposure to protons in the energy range encountered in the Van Allen belts and solar proton events can be correlated with the dose and energy of radiation. The primary cause of life shortening is nonleukemic cancers. Radiation also increased the rise of endometriosis (an abnormal proliferation of the lining of the uterus in females). Other effects associated with radiation exposures are lowered glucose tolerance and increased incidence of cataracts. Calculations of the relative risk of fatal cancers in the irradiated subjects reveal that the total body surface dose required to double the risk of death from cancer over a 20-year post exposure period varies with the linear energy transfer (LET) of the radiation. The ability to determine the integrated dose and LET spectrum in space radiation exposures of humans is, therefore, critical to the assessment of lifetime cancer risk.

  14. Simulation and experimental verification of prompt gamma-ray emissions during proton irradiation

    NASA Astrophysics Data System (ADS)

    Schumann, A.; Petzoldt, J.; Dendooven, P.; Enghardt, W.; Golnik, C.; Hueso-González, F.; Kormoll, T.; Pausch, G.; Roemer, K.; Fiedler, F.

    2015-05-01

    Irradiation with protons and light ions offers new possibilities for tumor therapy but has a strong need for novel imaging modalities for treatment verification. The development of new detector systems, which can provide an in vivo range assessment or dosimetry, requires an accurate knowledge of the secondary radiation field and reliable Monte Carlo simulations. This paper presents multiple measurements to characterize the prompt γ-ray emissions during proton irradiation and benchmarks the latest Geant4 code against the experimental findings. Within the scope of this work, the total photon yield for different target materials, the energy spectra as well as the γ-ray depth profile were assessed. Experiments were performed at the superconducting AGOR cyclotron at KVI-CART, University of Groningen. Properties of the γ-ray emissions were experimentally determined. The prompt γ-ray emissions were measured utilizing a conventional HPGe detector system (Clover) and quantitatively compared to simulations. With the selected physics list QGSP_BIC_HP, Geant4 strongly overestimates the photon yield in most cases, sometimes up to 50%. The shape of the spectrum and qualitative occurrence of discrete γ lines is reproduced accurately. A sliced phantom was designed to determine the depth profile of the photons. The position of the distal fall-off in the simulations agrees with the measurements, albeit the peak height is also overestimated. Hence, Geant4 simulations of prompt γ-ray emissions from irradiation with protons are currently far less reliable as compared to simulations of the electromagnetic processes. Deviations from experimental findings were observed and quantified. Although there has been a constant improvement of Geant4 in the hadronic sector, there is still a gap to close.

  15. Low-temperature tracking detectors

    NASA Astrophysics Data System (ADS)

    Niinikoski, T. O.; Abreu, M.; Anbinderis, P.; Anbinderis, T.; D'Ambrosio, N.; de Boer, W.; Borchi, E.; Borer, K.; Bruzzi, M.; Buontempo, S.; Chen, W.; Cindro, V.; Dezillie, B.; Dierlamm, A.; Eremin, V.; Gaubas, E.; Gorbatenko, V.; Granata, V.; Grigoriev, E.; Grohmann, S.; Hauler, F.; Heijne, E.; Heising, S.; Hempel, O.; Herzog, R.; Härkönen, J.; Ilyashenko, I.; Janos, S.; Jungermann, L.; Kalesinskas, V.; Kapturauskas, J.; Laiho, R.; Li, Z.; Luukka, P.; Mandic, I.; De Masi, R.; Menichelli, D.; Mikuz, M.; Militaru, O.; Nuessle, G.; O'Shea, V.; Pagano, S.; Paul, S.; Perea Solano, B.; Piotrzkowski, K.; Pirollo, S.; Pretzl, K.; Rahman, M.; Rato Mendes, P.; Rouby, X.; Ruggiero, G.; Smith, K.; Sousa, P.; Tuominen, E.; Tuovinen, E.; Vaitkus, J.; Verbitskaya, E.; da Viá, C.; Vlasenko, L.; Vlasenko, M.; Wobst, E.; Zavrtanik, M.; CERN RD39 Collaboration

    2004-03-01

    RD39 collaboration develops new detector techniques for particle trackers, which have to withstand fluences up to 1016 cm-2 of high-energy particles. The work focuses on the optimization of silicon detectors and their readout electronics while keeping the temperature as a free parameter. Our results so far suggest that the best operating temperature is around 130 K. We shall also describe in this paper how the current-injected mode of operation reduces the polarization of the bulk silicon at low temperatures, and how the engineering and materials problems related with vacuum and low temperature can be solved.

  16. Nuclear excitation functions from 40 to 200 MeV proton irradiation of terbium

    NASA Astrophysics Data System (ADS)

    Engle, Jonathan W.; Mashnik, Stepan G.; Parker, Lauren A.; Jackman, Kevin R.; Bitteker, Leo J.; Ullmann, John L.; Gulley, Mark S.; Pillai, Chandra; John, Kevin D.; Birnbaum, Eva R.; Nortier, Francois M.

    2016-01-01

    Nuclear formation cross sections are reported for 26 radionuclides, measured with 40-200 MeV proton irradiations of terbium foils. These data provide the basis for the production of medically relevant radionuclides (e.g., 152Tb, 155Tb, 155Eu, and 156Eu) and 153Gd, a potential source used in ongoing efforts to characterize stellar nucleosynthesis routes. Computational predictions from the ALICE2011, CEM03.03, Bertini, and INCL + ABLA codes are compared with newly measured data to contribute to the ongoing process of code development, and yields are calculated for selected radionuclides using measured data.

  17. Production of organic molecules in the outer solar system by proton irradiation - Laboratory simulations

    NASA Technical Reports Server (NTRS)

    Scattergood, T.; Lesser, P.; Owen, T.

    1975-01-01

    Preliminary experiments to investigate the formation of colored polymers and other interesting molecules by the irradiation of gas mixtures with protons are discussed. As in previous experiments, colored polymers were produced. An important feature of the present work is the presence or absence of absorption at 5 microns in the different materials produced; Titan is quite dark at this wavelength and Io is fairly bright. Such features may provide criteria for accepting or rejecting various materials produced in these experiments as reasonable coloring agents for the outer solar system.

  18. Proton irradiation test on the flight model radiation monitor for LISA Pathfinder

    NASA Astrophysics Data System (ADS)

    Mateos, I.; Lobo, A.; Ramos-Castro, J.; Sanjuán, J.; Diaz-Aguiló, M.; Wass, P. J.; Grimani, C.

    2010-05-01

    The design of the Radiation Monitor in the LISA Technology Package on board LISA Pathfinder is based on two silicon PIN diodes, placed parallel to each other in a telescopic configuration. One of them will be able to record spectral information of the particle hitting the diode. A test campaign for the Flight Model Radiation Monitor is proposed to verify its performance. This paper shows the results obtained with a simulated flight model geometry using GEANT4, to be compared with the real data that will be obtained in a proton irradiation facility.

  19. Behavior of optical thin-film materials and coatings under proton and gamma irradiation.

    PubMed

    Di Sarcina, Ilaria; Grilli, Maria Luisa; Menchini, Francesca; Piegari, Angela; Scaglione, Salvatore; Sytchkova, Anna; Zola, Danilo

    2014-02-01

    Optical materials and coatings are exposed to the flux of energetic particles when used in either space applications or nuclear energy plants. The study of their behavior in such an environment is important to avoid failure of the optical components during their operation. The optical performance of several thin-film materials ((HfO2, Ta2O5, Nb2O5, TiO2, SiO2) and coatings, under irradiation with high-dose gamma rays (5.8 MGy) and exposure to low-energy (60 keV) protons, has been investigated. Some variations of optical properties have been detected in silicon oxide after irradiation, while the other materials are stable in such conditions.

  20. Response of nanoclusters in a 9Cr ODS steel to 1 dpa, 525 ?C proton irradiation

    SciTech Connect

    Certain, Alicia; Field, Kevin G; Allen, Todd R.; Sridharan, K.; Miller, Michael K; Bentley, James; Busby, Jeremy T

    2010-01-01

    Ferritic-martensitic (F/M) alloys are expected to play an important role as cladding or structural components in Generation IV and other advanced nuclear systems operating in the temperature range 350-700 C and to doses up to 200 displacements per atom (dpa). Oxide dispersion strengthened (ODS) F/M steels have been developed to operate at higher temperatures than traditional F/M steels. These steels contain nanometer-sized Y-Ti-O nanoclusters for additional strengthening. A proton irradiation to 1 dpa at 525 C has been performed on a 9Cr ODS steel to determine the nanocluster stability at low dose. The evolution of the nanocluster population and the composition at the nanocluster-matrix interface were studied using electron microscopy and atom probe tomography. The data from this study are contrasted to those from a previous study on heavy-ion irradiated 9Cr ODS steel.

  1. Gene Expression Changes in Mouse Intestinal Tissue Following Whole-Body Proton or Gamma-Irradiation

    NASA Technical Reports Server (NTRS)

    Purgason, Ashley; Zhang, Ye; Mangala, Lingegowda; Nie, Ying; Gridley, Daila; Hamilton, Stanley R.; Seidel, Derek V.; Wu, Honglu

    2014-01-01

    Crew members face potential consequences following exposure to the space radiation environment including acute radiation syndrome and cancer. The space radiation environment is ample with protons, and numerous studies have been devoted to the understanding of the health consequences of proton exposures. In this project, C57BL/6 mice underwent whole-body exposure to 250 MeV of protons at doses of 0, 0.1, 0.5, 2 and 6 Gy and the gastrointestinal (GI) tract of each animal was dissected four hours post-irradiation. Standard H&E staining methods to screen for morphologic changes in the tissue showed an increase in apoptotic lesions for even the lowest dose of 0.1 Gy, and the percentage of apoptotic cells increased with increasing dose. Results of gene expression changes showed consistent up- or down- regulation, up to 10 fold, of a number of genes across exposure doses that may play a role in proton-induced oxidative stress including Gpx2. A separate study in C57BL/6 mice using the same four hour time point but whole-body gamma-irradiation showed damage to the small intestine with lesions appearing at the smallest dose of 0.05 Gy and increasing with increasing absorbed dose. Expressions of genes associated with oxidative stress processes were analyzed at four hours and twenty-four hours after exposure to gamma rays. We saw a much greater number of genes with significant up- or down-regulation twenty-four hours post-exposure as compared to the four hour time point. At both four hours and twenty-four hours post-exposure, Duox1 and Mpo underwent up-regulation for the highest dose of 6 Gy. Both protons and gamma rays lead to significant variation in gene expressions and these changes may provide insight into the mechanism of injury seen in the GI tract following radiation exposure. We have also completed experiments using a BALB/c mouse model undergoing whole-body exposure to protons. Doses of 0, 0.1, 1 and 2 Gy were used and results will be compared to the work mentioned

  2. Dose and dose rate effects of whole-body proton-irradiation on lymphocyte blastogenesis and hematological variables: part II

    NASA Technical Reports Server (NTRS)

    Pecaut, Michael J.; Gridley, Daila S.; Smith, Anna L.; Nelson, Gregory A.

    2002-01-01

    The goal of part II of this study was to evaluate functional characteristics of leukocytes and circulating blood cell parameters after whole-body proton irradiation at varying doses and at low- and high-dose-rates (LDR and HDR, respectively). C57BL/6 mice (n=51) were irradiated and euthanized at 4 days post-exposure for assay. Significant radiation dose- (but not dose-rate-) dependent decreases were observed in splenocyte responses to T and B cell mitogens when compared to sham-irradiated controls (P<0.001). Spontaneous blastogenesis, also significantly dose-dependent, was increased in both blood and spleen (P<0.001). Red blood cell counts, hemoglobin concentration, and hematocrit were decreased in a dose-dependent manner (P<0.05), whereas thrombocyte numbers were only slightly affected. Comparison of proton- and gamma-irradiated groups (both receiving 3 Gy at HDR) showed a higher level of spontaneous blastogenesis in blood leukocytes and a lower splenocyte response to concanavalin A following proton irradiation (P<0.05). There were no dose rate effects. Collectively, the data demonstrate that the measurements in blood and spleen were largely dependent upon the total dose of proton radiation and that an 80-fold difference in the dose rate was not a significant factor. A difference, however, was found between protons and gamma-rays in the degree of change induced in some of the measurements.

  3. Measurement of characteristic prompt gamma rays emitted from oxygen and carbon in tissue-equivalent samples during proton beam irradiation

    NASA Astrophysics Data System (ADS)

    Polf, Jerimy C.; Panthi, Rajesh; Mackin, Dennis S.; McCleskey, Matt; Saastamoinen, Antti; Roeder, Brian T.; Beddar, Sam

    2013-09-01

    The purpose of this work was to characterize how prompt gamma (PG) emission from tissue changes as a function of carbon and oxygen concentration, and to assess the feasibility of determining elemental concentration in tissues irradiated with proton beams. For this study, four tissue-equivalent water-sucrose samples with differing densities and concentrations of carbon, hydrogen, and oxygen were irradiated with a 48 MeV proton pencil beam. The PG spectrum emitted from each sample was measured using a high-purity germanium detector, and the absolute detection efficiency of the detector, average beam current, and delivered dose distribution were also measured. Changes to the total PG emission from 12C (4.44 MeV) and 16O (6.13 MeV) per incident proton and per Gray of absorbed dose were characterized as a function of carbon and oxygen concentration in the sample. The intensity of the 4.44 MeV PG emission per incident proton was found to be nearly constant for all samples regardless of their carbon concentration. However, we found that the 6.13 MeV PG emission increased linearly with the total amount (in grams) of oxygen irradiated in the sample. From the measured PG data, we determined that 1.64 × 107 oxygen PGs were emitted per gram of oxygen irradiated per Gray of absorbed dose delivered with a 48 MeV proton beam. These results indicate that the 6.13 MeV PG emission from 16O is proportional to the concentration of oxygen in tissue irradiated with proton beams, showing that it is possible to determine the concentration of oxygen within tissues irradiated with proton beams by measuring 16O PG emission.

  4. Measurement of characteristic prompt gamma rays emitted from oxygen and carbon in tissue-equivalent samples during proton beam irradiation

    PubMed Central

    Polf, Jerimy C; Panthi, Rajesh; Mackin, Dennis S; McCleskey, Matt; Saastamoinen, Antti; Roeder, Brian T; Beddar, Sam

    2013-01-01

    The purpose of this work was to characterize how prompt gamma (PG) emission from tissue changes as a function of carbon and oxygen concentration, and to assess the feasibility of determining elemental concentration in tissues irradiated with proton beams. For this study, four tissue-equivalent water-sucrose samples with differing densities and concentrations of carbon, hydrogen, and oxygen were irradiated with a 48 MeV proton pencil beam. The PG spectrum emitted from each sample was measured using a high-purity germanium detector, and the absolute detection efficiency of the detector, average beam current, and delivered dose distribution were also measured. Changes to the total PG emission from 12C (4.44 MeV) and 16O (6.13 MeV) per incident proton and per Gray of absorbed dose were characterized as a function of carbon and oxygen concentration in the sample. The intensity of the 4.44 MeV PG emission per incident proton was found to be nearly constant for all samples regardless of their carbon concentration. However, we found that the 6.13 MeV PG emission increased linearly with the total amount (in grams) of oxygen irradiated in the sample. From the measured PG data, we determined that 1.64 × 107 oxygen PGs were emitted per gram of oxygen irradiated per Gray of absorbed dose delivered with a 48 MeV proton beam. These results indicate that the 6.13 MeV PG emission from 16O is proportional to the concentration of oxygen in tissue irradiated with proton beams, showing that it is possible to determine the concentration of oxygen within tissues irradiated with proton beams by measuring 16O PG emission. PMID:23920051

  5. Low-temperature magnetic refrigerator

    DOEpatents

    Barclay, J.A.

    1983-05-26

    The invention relates to magnetic refrigeration and more particularly to low temperature refrigeration between about 4 and about 20 K, with an apparatus and method utilizing a belt of magnetic material passed in and out of a magnetic field with heat exchangers within and outside the field operably disposed to accomplish refrigeration.

  6. Low-temperature magnetic refrigerator

    DOEpatents

    Barclay, John A.

    1985-01-01

    The disclosure is directed to a low temperature 4 to 20 K. refrigeration apparatus and method utilizing a ring of magnetic material moving through a magnetic field. Heat exchange is accomplished in and out of the magnetic field to appropriately utilize the device to execute Carnot and Stirling cycles.

  7. Catalysts for low temperature oxidation

    DOEpatents

    Toops, Todd J.; Parks, III, James E.; Bauer, John C.

    2016-03-01

    The invention provides a composite catalyst containing a first component and a second component. The first component contains nanosized gold particles. The second component contains nanosized platinum group metals. The composite catalyst is useful for catalyzing the oxidation of carbon monoxide, hydrocarbons, oxides of nitrogen, and other pollutants at low temperatures.

  8. WE-D-17A-04: Magnetically Focused Proton Irradiation of Small Volume Targets

    SciTech Connect

    McAuley, G; Slater, J; Wroe, A

    2014-06-15

    Purpose: To explore the advantages of magnetic focusing for small volume proton irradiations and the potential clinical benefits for radiosurgery targets. The primary goal is to create narrow elongated proton beams of elliptical cross section with superior dose delivery characteristics compared to current delivery modalities (eg, collimated beams). In addition, more general beam shapes are also under investigation. Methods: Two prototype magnets consisting of 24 segments of samarium-cobalt (Sm2Co17) permanent magnetic material adhered into hollow cylinders were manufactured for testing. A single focusing magnet was placed on a positioning track on our Gantry 1 treatment table and 15 mm diameter proton beams with energies and modulation relevant to clinical radiosurgery applications (127 to 186 MeV, and 0 to 30 mm modulation) were delivered to a terminal water tank. Beam dose distributions were measured using a PTW diode detector and Gafchromic EBT2 film. Longitudinal and transverse dose profiles were analyzed and compared to data from Monte Carlo simulations analogous to the experimental setup. Results: The narrow elongated focused beam spots showed high elliptical symmetry indicating high magnet quality. In addition, when compared to unfocused beams, peak-to-entrance depth dose ratios were 11 to 14% larger (depending on presence or extent of modulation), and minor axis penumbras were 11 to 20% smaller (again depending on modulation) for focused beams. These results suggest that the use of rare earth magnet assemblies is practical and could improve dose-sparing of normal tissue and organs at risk while delivering enhanced dose to small proton radiosurgery targets. Conclusion: Quadrapole rare earth magnetic assemblies are a promising and inexpensive method to counteract particle out scatter that tends to degrade the peak to entrance performance of small field proton beams. Knowledge gained from current experiments will inform the design of a prototype treatment

  9. MECHANICAL PROPERTIES AND MICROSTRUCTURE IN LOW ACTIVATION MARTENSITIC STEELS F82H AND OPTIMAX AFTER 800 MEV PROTON IRRADIATION

    SciTech Connect

    Y. DAI; ET AL

    1999-10-01

    Low-activation martensitic steels, F82H (mod.) and Optimax-A, have been irradiated with 800-MeV protons up to 5.9 dpa. The tensile properties and microstructure have been studied. The results show that radiation hardening increases continuously with irradiation dose. F82H has lesser irradiation hardening as compared to Optimax-A in the present work and DIN1.4926 from a previous study. The irradiation embrittlement effects are evident in the materials since the uniform elongation is reduced sharply to less than 2%. However, all the irradiated samples ruptured in a ductile-fracture mode. Defect clusters have been observed. The size and the density of defect clusters increase with the irradiation dose. Precipitates are amorphous after irradiation.

  10. Engineering of silicon/HfO{sub 2} interface by variable energy proton irradiation

    SciTech Connect

    Maurya, Savita Maringanti, Radhakrishna; Tribedi, L. C.

    2014-08-18

    Surfaces and interfaces between materials are of paramount importance for various phenomena, such as painting a house, catalyst driven chemical reactions, intricate life processes, corrosion of materials, and fabrication of various semiconductor devices. Interface of silicon or other such substrates with any of the oxides has profound effect on the performance of metal oxide field effect transistors and other similar devices. Since a surface is an abrupt termination of a periodic crystal, surface atoms will have some unsaturated valence electrons and these unsaturated bonds at the semiconductor surface make it chemically highly reactive. Other than annealing, there is not much that can be done to manage these unsaturated bonds. This study was initiated to explore the possibility of repairing these unsaturated dangling bonds that are formed at the silicon and oxide interface during the deposition of oxide layer above silicon, by the use of proton irradiation. In order to improve the interface characteristics, we present a method to modify the interface of silicon and hafnium dioxide after its fabrication, through proton irradiation. Results of the study are promising and probably this method might be used along with other methods such as annealing to modify the interface, after its fabrication.

  11. Production of radionuclides in artificial meteorites irradiated isotropically with 600 MeV protons

    NASA Technical Reports Server (NTRS)

    Michel, R.; Dragovitsch, P.; Englert, P.; Herpers, U.

    1986-01-01

    The understanding of the production of cosmogenic nuclides in small meteorites (R is less than 40 cm) still is not satisfactory. The existing models for the calculation of depth dependent production rates do not distinguish between the different types of nucleons reacting in a meteorite. They rather use general depth dependent particle fluxes to which cross sections have to be adjusted to fit the measured radionuclide concentrations. Some of these models can not even be extended to zero meteorite sizes without logical contradictions. Therefore, a series of three thick target irradiations was started at the 600 MeV proton beam of the CERN isochronuous cyclotron in order to study the interactions of small stony meteorites with galactic protons. The homogeneous 4 pi irradiation technique used provides a realistic meteorite model which allows a direct comparison of the measured depth profiles with those in real meteorites. Moreover, by the simultaneous measurement of thin target production cross sections one can differentiate between the contributions of primary and secondary nucleons over the entire volume of the artificial meteorite.

  12. Spherically shaped active transducer based on proton-irradiated vinylidene fluoride-trifluoroethylene 70/30 mol % copolymer

    SciTech Connect

    Lau, S.T.; Chan, H.L.W.; Choy, C.L.; Cheung, W.Y.; Wong, S.P.

    2006-05-15

    Spherically shaped active transducers using proton-irradiated vinylidene fluoride-trifluoroethylene 70/30 mol % copolymer films as the active elements are described. The copolymer films prepared by hot compression molding were irradiated with a high energy proton over a broad dose range (20-250 Mrad). The electrostrictive and piezoelectric responses of the copolymer have been characterized before subsequent transducer fabrication. The performances of the focused transducers constructed with a 4 mm aperture size and epoxy backing were evaluated under dc bias voltages. The transducers with focal lengths of 17.4-19.0 mm and a center frequency of 19 MHz display a broad bandwidth up to 94%. Besides, the transmitting output of the transducers increases with the dc bias voltage. For the copolymer active element irradiated at a proton dose of 107 Mrad, the transducer shows the highest transmitting voltage response of 1.34 kPa/V.

  13. SPICE-NIRS Microbeam: a focused vertical system for proton irradiation of a single cell for radiobiological research

    PubMed Central

    Konishi, Teruaki; Oikawa, Masakazu; Suya, Noriyoshi; Ishikawa, Takahiro; Maeda, Takeshi; Kobayashi, Alisa; Shiomi, Naoko; Kodama, Kumiko; Hamano, Tsuyoshi; Homma-Takeda, Shino; Isono, Mayu; Hieda, Kotaro; Uchihori, Yukio; Shirakawa, Yoshiyuki

    2013-01-01

    The Single Particle Irradiation system to Cell (SPICE) facility at the National Institute of Radiological Sciences (NIRS) is a focused vertical microbeam system designed to irradiate the nuclei of adhesive mammalian cells with a defined number of 3.4 MeV protons. The approximately 2-μm diameter proton beam is focused with a magnetic quadrupole triplet lens and traverses the cells contained in dishes from bottom to top. All procedures for irradiation, such as cell image capturing, cell recognition and position calculation, are automated. The most distinctive characteristic of the system is its stability and high throughput; i.e. 3000 cells in a 5 mm × 5 mm area in a single dish can be routinely irradiated by the 2-μm beam within 15 min (the maximum irradiation speed is 400 cells/min). The number of protons can be set as low as one, at a precision measured by CR-39 detectors to be 99.0%. A variety of targeting modes such as fractional population targeting mode, multi-position targeting mode for nucleus irradiation and cytoplasm targeting mode are available. As an example of multi-position targeting irradiation of mammalian cells, five fluorescent spots in a cell nucleus were demonstrated using the γ-H2AX immune-staining technique. The SPICE performance modes described in this paper are in routine use. SPICE is a joint-use research facility of NIRS and its beam times are distributed for collaborative research. PMID:23287773

  14. SPICE-NIRS microbeam: a focused vertical system for proton irradiation of a single cell for radiobiological research.

    PubMed

    Konishi, Teruaki; Oikawa, Masakazu; Suya, Noriyoshi; Ishikawa, Takahiro; Maeda, Takeshi; Kobayashi, Alisa; Shiomi, Naoko; Kodama, Kumiko; Hamano, Tsuyoshi; Homma-Takeda, Shino; Isono, Mayu; Hieda, Kotaro; Uchihori, Yukio; Shirakawa, Yoshiyuki

    2013-07-01

    The Single Particle Irradiation system to Cell (SPICE) facility at the National Institute of Radiological Sciences (NIRS) is a focused vertical microbeam system designed to irradiate the nuclei of adhesive mammalian cells with a defined number of 3.4 MeV protons. The approximately 2-μm diameter proton beam is focused with a magnetic quadrupole triplet lens and traverses the cells contained in dishes from bottom to top. All procedures for irradiation, such as cell image capturing, cell recognition and position calculation, are automated. The most distinctive characteristic of the system is its stability and high throughput; i.e. 3000 cells in a 5 mm × 5 mm area in a single dish can be routinely irradiated by the 2-μm beam within 15 min (the maximum irradiation speed is 400 cells/min). The number of protons can be set as low as one, at a precision measured by CR-39 detectors to be 99.0%. A variety of targeting modes such as fractional population targeting mode, multi-position targeting mode for nucleus irradiation and cytoplasm targeting mode are available. As an example of multi-position targeting irradiation of mammalian cells, five fluorescent spots in a cell nucleus were demonstrated using the γ-H2AX immune-staining technique. The SPICE performance modes described in this paper are in routine use. SPICE is a joint-use research facility of NIRS and its beam times are distributed for collaborative research. PMID:23287773

  15. Generation of a quasi-monoergetic proton beam from laser-irradiated sub-micron droplets

    SciTech Connect

    Ter-Avetisyan, S.; Ramakrishna, B.; Prasad, R.; Borghesi, M.; Nickles, P. V.; Steinke, S.; Schnuerer, M.; Popov, K. I.; Ramunno, L.; Zmitrenko, N. V.; Bychenkov, V. Yu.

    2012-07-15

    Proton bursts with a narrow spectrum at an energy of (2.8 {+-} 0.3 MeV) are accelerated from sub-micron water spray droplets irradiated by high-intensity ({approx}5 Multiplication-Sign 10{sup 19} W/cm{sup 2}), high-contrast ({approx}10{sup 10}), ultra-short (40 fs) laser pulses. The acceleration is preferentially in the laser propagation direction. The explosion dynamics is governed by a residual ps-scale laser pulse pedestal which 'mildly' preheats the droplet and changes its density profile before the arrival of the high intensity laser pulse peak. As a result, the energetic electrons extracted from the modified target by the high-intensity part of the laser pulse establish an anisotropic electrostatic field which results in anisotropic Coulomb explosion and proton acceleration predominantly in the forward direction. Hydrodynamic simulations of the target pre-expansion and 3D particle-in-cell simulations of the measured energy and anisotropy of the proton emission have confirmed the proposed acceleration scenario.

  16. Characterization of MeV proton acceleration from double pulse irradiation of foil targets

    NASA Astrophysics Data System (ADS)

    Kerr, S.; Mo, M. Z.; Masud, R.; Tiedje, H. F.; Tsui, Y.; Fedosejevs, R.; Link, A.; Patel, P.; McLean, H. S.; Hazi, A.; Chen, H.; Ceurvorst, L.; Norreys, P.

    2014-10-01

    We report on the experimental characterization of proton acceleration from double-pulse irradiation of um-scale foil targets. Temporally separated sub-picosecond pulses have been shown to increase the conversion efficiency of laser energy to MeV protons. Here, two 700 fs, 1 ω pulses were separated by 1 to 5 ps; total beam energy was 100 J, with 5-20% of the total energy contained within the first pulse. In contrast to the ultraclean beams used in previous experiments, prepulse energies on the order of 10 mJ were present in the current experiments which appear to have a moderating effect on the enhancement. Proton beam measurements were made with radiochromic film stacks, as well as magnetic spectrometers. The effect on electron generation was measured using Kα emission from buried Cu tracer layers, while specular light diagnostics (FROG, reflection spectralon) indicated the laser coupling efficiency into the target. The results obtained will be presented and compared to PIC simulations. Work by LLNL was performed under the auspices of U.S. DOE under contract DE-AC52-07NA27344.

  17. MeV single-ion beam irradiation of mammalian cells using the Surrey vertical nanobeam, compared with broad proton beam and X-ray irradiations

    NASA Astrophysics Data System (ADS)

    Prakrajang, K.; Jeynes, J. C. G.; Merchant, M. J.; Kirkby, K.; Kirkby, N.; Thopan, P.; Yu, L. D.

    2013-07-01

    As a part of a systematic study on mechanisms involved in physical cancer therapies, this work investigated response of mammalian cells to ultra-low-dose ion beam irradiation. The ion beam irradiation was performed using the recently completed nanobeam facility at the Surrey Ion Beam Centre. A scanning focused vertical ion nano-beam was applied to irradiate Chinese hamster V79 cells. The V79 cells were irradiated in two different beam modes, namely, focused single ion beam and defocused scanning broad ion beam of 3.8-MeV protons. The single ion beam was capable of irradiating a single cell with a precisely controlled number of the ions to extremely low doses. After irradiation and cell incubation, the number of surviving colonies as a function of the number of the irradiating ions was measured for the cell survival fraction curve. A lower survival for the single ion beam irradiation than that of the broad beam case implied the hypersensitivity and bystander effect. The ion-beam-induced cell survival curves were compared with that from 300-kV X-ray irradiation. Theoretical studies indicated that the cell death in single ion irradiation mainly occurred in the cell cycle phases of cell division and intervals between the cell division and the DNA replication. The success in the experiment demonstrated the Surrey vertical nanobeam successfully completed.

  18. Recovery of damage in rad-hard MOS devices during and after irradiation by electrons, protons, alphas, and gamma rays

    NASA Technical Reports Server (NTRS)

    Brucker, G. J.; Van Gunten, O.; Stassinopoulos, E. G.; Shapiro, P.; August, L. S.; Jordan, T. M.

    1983-01-01

    This paper reports on the recovery properties of rad-hard MOS devices during and after irradiation by electrons, protons, alphas, and gamma rays. The results indicated that complex recovery properties controlled the damage sensitivities of the tested parts. The results also indicated that damage sensitivities depended on dose rate, total dose, supply bias, gate bias, transistor type, radiation source, and particle energy. The complex nature of these dependencies make interpretation of LSI device performance in space (exposure to entire electron and proton spectra) difficult, if not impossible, without respective ground tests and analyses. Complete recovery of n-channel shifts was observed, in some cases within hours after irradiation, with equilibrium values of threshold voltages greater than their pre-irradiation values. This effect depended on total dose, radiation source, and gate bias during exposure. In contrast, the p-channel shifts recovered only 20 percent within 30 days after irradiation.

  19. Strain hardening and plastic instability properties of austenitic stainless steels after proton and neutron irradiation

    NASA Astrophysics Data System (ADS)

    Byun, T. S.; Farrell, K.; Lee, E. H.; Hunn, J. D.; Mansur, L. K.

    2001-10-01

    Strain hardening and plastic instability properties were analyzed for EC316LN, HTUPS316, and AL6XN austenitic stainless steels after combined 800 MeV proton and spallation neutron irradiation to doses up to 10.7 dpa. The steels retained good strain-hardening rates after irradiation, which resulted in significant uniform strains. It was found that the instability stress, the stress at the onset of necking, had little dependence on the irradiation dose. Tensile fracture stress and strain were calculated from the stress-strain curve data and were used to estimate fracture toughness using an existing model. The doses to plastic instability and fracture, the accumulated doses at which the yield stress reaches instability stress or fracture stress, were predicted by extrapolation of the yield stress, instability stress, and fracture stress to higher dose. The EC316LN alloy required the highest doses for plastic instability and fracture. Plastic deformation mechanisms are discussed in relation to the strain-hardening properties of the austenitic stainless steels.

  20. The comparison of microstructure and nanocluster evolution in proton and neutron irradiated Fe-9%Cr ODS steel to 3 dpa at 500 °C

    NASA Astrophysics Data System (ADS)

    Swenson, M. J.; Wharry, J. P.

    2015-12-01

    A model Fe-9%Cr oxide dispersion strengthened (ODS) steel was irradiated with protons or neutrons to a dose of 3 displacements per atom (dpa) at a temperature of 500 °C, enabling a direct comparison of ion to neutron irradiation effects at otherwise fixed irradiation conditions. The irradiated microstructures were characterized using transmission electron microscopy and atom probe tomography including cluster analysis. Both proton and neutron irradiations produced a comparable void and dislocation loop microstructure. However, the irradiation response of the Ti-Y-O oxide nanoclusters varied. Oxides remained stable under proton irradiation, but exhibited dissolution and an increase in Y:Ti composition ratio under neutron irradiation. Both proton and neutron irradiation also induced varying extents of Si, Ni, and Mn clustering at existing oxide nanoclusters. Protons are able to reproduce the void and loop microstructure of neutron irradiation carried out to the same dose and temperature. However, since nanocluster evolution is controlled by both diffusion and ballistic impacts, protons are rendered unable to reproduce the nanocluster evolution of neutron irradiation at the same dose and temperature.

  1. Diffusion length variation in 0.5- and 3-MeV-proton-irradiated, heteroepitaxial indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Weinberg, Irving; Flood, Dennis J.

    1993-01-01

    Indium phosphide (InP) solar cells are more radiation resistant than gallium arsenide (GaAs) and silicon (Si) solar cells, and their growth by heteroepitaxy offers additional advantages leading to the development of light weight, mechanically strong, and cost-effective cells. Changes in heteroepitaxial InP cell efficiency under 0.5- and 3-MeV proton irradiations have been explained by the variation in the minority-carrier diffusion length. The base diffusion length versus proton fluence was calculated by simulating the cell performance. The diffusion length damage coefficient, K(sub L), was also plotted as a function of proton fluence.

  2. Total Dose Effects on Bipolar Integrated Circuits at Low Temperature

    NASA Technical Reports Server (NTRS)

    Johnston, A. H.; Swimm, R. T.; Thorbourn, D. O.

    2012-01-01

    Total dose damage in bipolar integrated circuits is investigated at low temperature, along with the temperature dependence of the electrical parameters of internal transistors. Bandgap narrowing causes the gain of npn transistors to decrease far more at low temperature compared to pnp transistors, due to the large difference in emitter doping concentration. When irradiations are done at temperatures of -140 deg C, no damage occurs until devices are warmed to temperatures above -50 deg C. After warm-up, subsequent cooling shows that damage is then present at low temperature. This can be explained by the very strong temperature dependence of dispersive transport in the continuous-time-random-walk model for hole transport. For linear integrated circuits, low temperature operation is affected by the strong temperature dependence of npn transistors along with the higher sensitivity of lateral and substrate pnp transistors to radiation damage.

  3. Dose and dose rate effects of whole-body proton irradiation on leukocyte populations and lymphoid organs: part I

    NASA Technical Reports Server (NTRS)

    Gridley, Daila S.; Pecaut, Michael J.; Dutta-Roy, Radha; Nelson, Gregory A.

    2002-01-01

    The goal of part I of this study was to evaluate the effects of whole-body proton irradiation on lymphoid organs and specific leukocyte populations. C57BL/6 mice were exposed to the entry region of the proton Bragg curve to total doses of 0.5 gray (Gy), 1.5 Gy, and 3.0 Gy, each delivered at a low dose rate (LDR) of 1 cGy/min and high dose rate (HDR) of 80 cGy/min. Non-irradiated and 3 Gy HDR gamma-irradiated groups were included as controls. At 4 days post-irradiation, highly significant radiation dose-dependent reductions were observed in the mass of both lymphoid organs and the numbers of leukocytes and T (CD3(+)), T helper (CD3(+)/CD4(+)), T cytotoxic (CD3(+)/CD8(+)), and B (CD19(+)) cells in both blood and spleen. A less pronounced dose effect was noted for natural killer (NK1.1(+) NK) cells in spleen. Monocyte, but not granulocyte, counts in blood were highly dose-dependent. The numbers for each population generally tended to be lower with HDR than with LDR radiation; a significant dose rate effect was found in the percentages of T and B cells, monocytes, and granulocytes and in CD4(+):CD8(+) ratios. These data indicate that mononuclear cell response to the entry region of the proton Bragg curve is highly dependent upon the total dose and that dose rate effects are evident with some cell types. Results from gamma- and proton-irradiated groups (both at 3 Gy HDR) were similar, although proton-irradiation gave consistently lower values in some measurements.

  4. Ferroelectric domain freezing and charge conduction in proton-irradiated K(H0.36D0.64)2PO4

    NASA Astrophysics Data System (ADS)

    Kim, Se-Hun; Oh, B. H.; Lee, Cheol Eui

    2016-08-01

    We have studied the effects of proton irradiation in K(H0.36D0.64)2PO4 single crystals by employing impedance spectroscopy. Frequency-dependent dielectric loss measurements allowed us to investigate changes in the domain wall dynamics of a proton-irradiated crystal with a ferroelectric phase transition temperature raised by 5 K. Thus, the increase caused by proton irradiation in the activation energy of the domain freezing in the direction of the hydrogen bonds was found to be significantly greater than in the case of KH2PO4. Furthermore, the temperature dependence of the power-law exponent n in the frequency-dependent electrical conductivity in the proton-conducting systems manifested changes arising from the proton irradiation in the interactions between the mobile ionic (proton) charges and their environments.

  5. Low Temperature Waste Immobilization Testing Vol. I

    SciTech Connect

    Russell, Renee L.; Schweiger, Michael J.; Westsik, Joseph H.; Hrma, Pavel R.; Smith, D. E.; Gallegos, Autumn B.; Telander, Monty R.; Pitman, Stan G.

    2006-09-14

    The Pacific Northwest National Laboratory (PNNL) is evaluating low-temperature technologies to immobilize mixed radioactive and hazardous waste. Three waste forms—alkali-aluminosilicate hydroceramic cement, “Ceramicrete” phosphate-bonded ceramic, and “DuraLith” alkali-aluminosilicate geopolymer—were selected through a competitive solicitation for fabrication and characterization of waste-form properties. The three contractors prepared their respective waste forms using simulants of a Hanford secondary waste and Idaho sodium bearing waste provided by PNNL and characterized their waste forms with respect to the Toxicity Characteristic Leaching Procedure (TCLP) and compressive strength. The contractors sent specimens to PNNL, and PNNL then conducted durability (American National Standards Institute/American Nuclear Society [ANSI/ANS] 16.1 Leachability Index [LI] and modified Product Consistency Test [PCT]) and compressive strength testing (both irradiated and as-received samples). This report presents the results of these characterization tests.

  6. Ultra-low temperature MAS-DNP

    NASA Astrophysics Data System (ADS)

    Lee, Daniel; Bouleau, Eric; Saint-Bonnet, Pierre; Hediger, Sabine; De Paëpe, Gaël

    2016-03-01

    Since the infancy of NMR spectroscopy, sensitivity and resolution have been the limiting factors of the technique. Regular essential developments on this front have led to the widely applicable, versatile, and powerful spectroscopy that we know today. However, the Holy Grail of ultimate sensitivity and resolution is not yet reached, and technical improvements are still ongoing. Hence, high-field dynamic nuclear polarization (DNP) making use of high-frequency, high-power microwave irradiation of electron spins has become very promising in combination with magic angle sample spinning (MAS) solid-state NMR experiments. This is because it leads to a transfer of the much larger polarization of these electron spins under suitable irradiation to surrounding nuclei, greatly increasing NMR sensitivity. Currently, this boom in MAS-DNP is mainly performed at minimum sample temperatures of about 100 K, using cold nitrogen gas to pneumatically spin and cool the sample. This Perspective deals with the desire to improve further the sensitivity and resolution by providing "ultra"-low temperatures for MAS-DNP, using cryogenic helium gas. Different designs on how this technological challenge has been overcome are described. It is shown that stable and fast spinning can be attained for sample temperatures down to 30 K using a large cryostat developed in our laboratory. Using this cryostat to cool a closed-loop of helium gas brings the additional advantage of sample spinning frequencies that can greatly surpass those achievable with nitrogen gas, due to the differing fluidic properties of these two gases. It is shown that using ultra-low temperatures for MAS-DNP results in substantial experimental sensitivity enhancements and according time-savings. Access to this temperature range is demonstrated to be both viable and highly pertinent.

  7. In-growth of an electrically active defect in high-purity silicon after proton irradiation

    SciTech Connect

    Nylandsted Larsen, A.; Juul Pedersen, H.; Christian Petersen, M.; Privitera, V.; Gurimskaya, Y.; Mesli, A.

    2013-12-14

    Defect-related energy levels in the lower half of the band gap of silicon have been studied with transient-capacitance techniques in high-purity, carbon and oxygen lean, plasma-enhanced chemical-vapor deposition grown, n-and p-type silicon layers after 2-MeV proton irradiations at temperatures at or just below room temperature. The in-growth of a distinct line in deep-level transient spectroscopy spectra, corresponding to a level in the band gap at E{sub V} + 0.357 eV where E{sub V} is the energy of the valence band edge, takes place for anneal temperatures at around room temperature with an activation energy of 0.95 ± 0.08 eV. The line disappears at an anneal temperature of around 450 K. The corresponding defect is demonstrated not to contain boron, carbon, oxygen, or phosphorus. Possible defect candidates are discussed.

  8. Influence of Proton Irradiation on Angular Dependence of Second Generation (2G)HTS

    SciTech Connect

    Shiroyanagi, Y.; Greene, G.; Gupta, R.; Sampson, W.

    2011-05-01

    In the Facility for Rare Isotope Beams (FRIB) the quadrupoles in the fragment separator are exposed to very high radiation and heat loads. High Temperature Superconductors (HTS) are a good candidate for these magnets because they can be used at {approx}30-50 K and tolerate higher heat generation than Nb-Ti magnets. Radiation damage studies of HTS wires are crucial to ensure that they will survive in a high radiation environment. HTS wires from two vendors were studied. Samples of 2G HTS wires from SuperPower and American Superconductor (ASC) were irradiated with a 42 {mu}A, 142 MeV proton beam from the Brookhaven Linac Isotope Producer (BLIP). The angular dependence of the critical current was measured in magnetic fields at 77K.

  9. Use of the point defect model to interpret the iron oxidation kinetics under proton irradiation

    SciTech Connect

    Lapuerta, S.; Moncoffre, N.; Jaffrezic, H.; Millard-Pinard, N.; Bererd, N.; Esnouf, C.; Crusset, D.

    2007-03-15

    This article concerns the study of iron corrosion in wet air under mega-electron-volt proton irradiation for different fluxes at room temperature and with a relative humidity fixed to 45%. Oxidized iron sample surfaces are characterized by ion beam analysis (Rutherford backscattering spectrometry and elastic recoil detection analysis), for the elemental analysis. The structural and physicochemical characterization is performed using the x-ray photoelectron spectroscopy and transmission electron microscopy techniques. We have also measured the iron oxidation kinetics. Radiation enhanced diffusion and transport processes have been evidenced. The modeling of the experimental data shows that the apparent oxygen diffusion coefficient increases whereas the oxygen transport velocity decreases as function of flux. Finally, the point defect model has been used to determine the electric field value in the samples. Results have shown that the transport process can be attributed to the presence of an electrical potential gradient.

  10. Hot cell purification of strontium-82, 85 and other isotopes from proton irradiated molybdenum

    DOEpatents

    Bentley, Glenn E.; Barnes, John W.

    1981-01-01

    A process suitable for producing curie quantities of quite pure Sr-82,85 is given. After a Mo target is irradiated with energetic protons having energies greater than about 200 MeV, thus producing a large number of radioactive species, the particular species of Sr-82,85 are substantially separated from the other products by a 6-step process. The process comprises dissolution of the target in H.sub.2 O.sub.2, followed by use of several ion exchange resins, extraction with an organophosphorus compound, and several adjustments of pH values. Other embodiments include processes for producing relatively pure long-lived Rb isotopes, Y-88, and Zr-88.

  11. Hot cell purification of strontium-82, 85 and other isotopes from proton irradiated molybdenum

    DOEpatents

    Bentley, G.E.; Barnes, J.W.

    1979-10-17

    A process suitable for producing curie quantities of quite pure Sr-82,85 is given. After a Mo target is irradiated with energetic protons having energies greater than about 200 MeV, thus producing a large number of radioactive species, the particular species of Sr-82,85 are substantially separated from the other products by a 6-step process. The process comprises dissolution of the target in H/sub 2/O/sub 2/, followed by use of several ion exchange resins, extraction with an organophosphorus compound, and several adjustments of pH values. Other embodiments include processes for producing relatively pure long-lived Rb isotopes, Y-88, and Zr-88.

  12. Meteorite-catalyzed syntheses of nucleosides and of other prebiotic compounds from formamide under proton irradiation

    PubMed Central

    Saladino, Raffaele; Carota, Eleonora; Botta, Giorgia; Kapralov, Mikhail; Timoshenko, Gennady N.; Rozanov, Alexei Y.; Krasavin, Eugene; Di Mauro, Ernesto

    2015-01-01

    Liquid formamide has been irradiated by high-energy proton beams in the presence of powdered meteorites, and the products of the catalyzed resulting syntheses were analyzed by mass spectrometry. Relative to the controls (no radiation, or no formamide, or no catalyst), an extremely rich, variegate, and prebiotically relevant panel of compounds was observed. The meteorites tested were representative of the four major classes: iron, stony iron, chondrites, and achondrites. The products obtained were amino acids, carboxylic acids, nucleobases, sugars, and, most notably, four nucleosides: cytidine, uridine, adenosine, and thymidine. In accordance with theoretical studies, the detection of HCN oligomers suggests the occurrence of mechanisms based on the generation of radical cyanide species (CN·) for the synthesis of nucleobases. Given that many of the compounds obtained are key components of extant organisms, these observations contribute to outline plausible exogenous high-energy–based prebiotic scenarios and their possible boundary conditions, as discussed. PMID:25870268

  13. Measurement of temperature-dependent defect diffusion in proton-irradiated GaN(Mg, H)

    SciTech Connect

    Fleming, R. M.; Myers, S. M.

    2006-08-15

    Deuterated p-type GaN(Mg,{sup 2}H) films were irradiated at room temperature with 1 MeV protons to create native point defects with a concentration approximately equal to the Mg doping (5x10{sup 19} cm{sup -3}). The samples were then annealed isothermally at a succession of temperatures while monitoring the infrared absorption due to the H local mode of the MgH defect. As the samples were annealed, the MgH absorption signal decreased and a new mode at slightly higher frequency appeared, which has been associated with the approach of a mobile nitrogen interstitial. We used the time dependence of the MgH absorption to obtain a diffusion barrier of the nitrogen interstitial in p-type GaN of 1.99 eV. This is in good agreement with theoretical calculations of nitrogen interstitial motion in GaN.

  14. Experimental study of pyrolytic boron nitride at high temperature with and without proton and VUV irradiations

    NASA Astrophysics Data System (ADS)

    Balat-Pichelin, M.; Eck, J.; Heurtault, S.; Glénat, H.

    2014-09-01

    In the frame of future exploration missions such as Solar Probe Plus (NASA) and PHOIBOS (ESA), research was carried out to study pyrolytic BN material envisaged as coating for their heat shields. The physico-chemical behavior of CVD pBN at very high temperature with or without hydrogen ions and VUV (Vacuum Ultra-Violet) irradiations was studied in high vacuum together with the in situ measurement of the thermal radiative properties conditioning the thermal equilibrium of the heat shield. Experimental results obtained on massive pBN samples are presented through in situ mass spectrometry and mass loss rate, and post-test microstructural characterization by XRD, SEM, AFM and nano-indentation techniques, some of them leading to mechanical properties. It could be concluded that synergistic effect of high temperature, protons and VUV radiation has an impact on the emission of gaseous species, the mass loss rate and the mechanical properties of the material.

  15. Real-Time Time-Dependent DFT Study of Electronic Stopping in Semiconductors under Proton Irradiation

    NASA Astrophysics Data System (ADS)

    Yost, Dillon C.; Reeves, Kyle G.; Kanai, Yosuke

    Understanding the detailed mechanisms of how highly energetic charged particles transfer their kinetic energy to electronic excitations in materials has become an important topic in various technologies ranging from nuclear energy applications to integrated circuits for space missions. In this work, we use our new large-scale real-time time-dependent density functional theory simulation to investigate details of the ion-velocity-dependent dynamics of electronic excitations in the electronic stopping process. In particular, we will discuss how point defects in semiconductor materials influence the electronic stopping process under proton irradiation, using silicon carbide (3C-SiC) as a representative material due to its great technological importance. Additionally, we will provide atomistic insights into existing analytical models that are based on the plane-wave Born approximation by examining velocity-dependence of the projectile charge from first-principles simulations.

  16. Measurement of temperature-dependent defect diffusion in proton-irradiated GaN(Mg, H).

    SciTech Connect

    Myers, Samuel Maxwell, Jr.; Fleming, Robert M.

    2005-06-01

    Deuterated p-type GaN(Mg,{sup 2}H) films were irradiated at room temperature with 1 MeV protons to create native point defects with a concentration approximately equal to the Mg doping (5 x 10{sup 19} cm{sup -3}). The samples were then annealed isothermally at a succession of temperatures while monitoring the infrared absorption due to the H local mode of the MgH defect. As the samples were annealed, the MgH absorption signal decreased and a new mode at slightly higher frequency appeared, which has been associated with the approach of a mobile nitrogen interstitial. We used the time dependence of the MgH absorption to obtain a diffusion barrier of the nitrogen interstitial in p-type GaN of 1.99 eV. This is in good agreement with theoretical calculations of nitrogen interstitial motion in GaN.

  17. Interaction of defects and H in proton-irradiated GaN(Mg, H)

    SciTech Connect

    Myers, S.M.; Seager, C.H.

    2005-05-01

    Magnesium-doped, p-type GaN containing H was irradiated with MeV protons at room temperature and then annealed at a succession of increasing temperatures, with the behavior of defects and H in the material being followed through infrared absorption spectroscopy, nuclear-reaction analysis of the H, and photoluminescence. The results support the annihilation of Ga Frenkel pairs near room temperature, leaving the N interstitial and N vacancy to influence the elevated-temperature behavior. Multiple changes are observed with increasing temperature, ending with thermal release of the H above 700 deg. C. These effects are interpreted in terms of a succession of complexes involving Mg, the point defects, and H.

  18. Meteorite-catalyzed syntheses of nucleosides and of other prebiotic compounds from formamide under proton irradiation.

    PubMed

    Saladino, Raffaele; Carota, Eleonora; Botta, Giorgia; Kapralov, Mikhail; Timoshenko, Gennady N; Rozanov, Alexei Y; Krasavin, Eugene; Di Mauro, Ernesto

    2015-05-26

    Liquid formamide has been irradiated by high-energy proton beams in the presence of powdered meteorites, and the products of the catalyzed resulting syntheses were analyzed by mass spectrometry. Relative to the controls (no radiation, or no formamide, or no catalyst), an extremely rich, variegate, and prebiotically relevant panel of compounds was observed. The meteorites tested were representative of the four major classes: iron, stony iron, chondrites, and achondrites. The products obtained were amino acids, carboxylic acids, nucleobases, sugars, and, most notably, four nucleosides: cytidine, uridine, adenosine, and thymidine. In accordance with theoretical studies, the detection of HCN oligomers suggests the occurrence of mechanisms based on the generation of radical cyanide species (CN·) for the synthesis of nucleobases. Given that many of the compounds obtained are key components of extant organisms, these observations contribute to outline plausible exogenous high-energy-based prebiotic scenarios and their possible boundary conditions, as discussed. PMID:25870268

  19. Meteorite-catalyzed syntheses of nucleosides and of other prebiotic compounds from formamide under proton irradiation.

    PubMed

    Saladino, Raffaele; Carota, Eleonora; Botta, Giorgia; Kapralov, Mikhail; Timoshenko, Gennady N; Rozanov, Alexei Y; Krasavin, Eugene; Di Mauro, Ernesto

    2015-05-26

    Liquid formamide has been irradiated by high-energy proton beams in the presence of powdered meteorites, and the products of the catalyzed resulting syntheses were analyzed by mass spectrometry. Relative to the controls (no radiation, or no formamide, or no catalyst), an extremely rich, variegate, and prebiotically relevant panel of compounds was observed. The meteorites tested were representative of the four major classes: iron, stony iron, chondrites, and achondrites. The products obtained were amino acids, carboxylic acids, nucleobases, sugars, and, most notably, four nucleosides: cytidine, uridine, adenosine, and thymidine. In accordance with theoretical studies, the detection of HCN oligomers suggests the occurrence of mechanisms based on the generation of radical cyanide species (CN·) for the synthesis of nucleobases. Given that many of the compounds obtained are key components of extant organisms, these observations contribute to outline plausible exogenous high-energy-based prebiotic scenarios and their possible boundary conditions, as discussed.

  20. Dosimetric Characteristics of a Two-Dimensional Diode Array Detector Irradiated with Passively Scattered Proton Beams

    PubMed Central

    Liengsawangwong, Praimakorn; Sahoo, Nanayan; Ding, Xiaoning; Lii, MingFwu; Gillin, Michale T.; Zhu, Xiaorong Ronald

    2015-01-01

    Purpose: To evaluate the dosimetric characteristics of a two-dimensional (2D) diode array detector irradiated with passively scattered proton beams. Materials and Methods: A diode array detector, MapCHECK (Model 1175, Sun Nuclear, Melbourne, FL, USA) was characterized in passive-scattered proton beams. The relative sensitivity of the diodes and absolute dose calibration were determined using a 250 MeV beam. The pristine Bragg curves (PBCs) measured by MapCHECK diodes were compared with those of an ion chamber using a range shift method. The water-equivalent thickness (WET) of the diode array detector’s intrinsic buildup also was determined. The inverse square dependence, linearity, and other proton dosimetric quantities measured by MapCHECK were also compared with those of the ion chambers. The change in the absolute dose response of the MapCHECK as a function of accumulated radiation dose was used as an indicator of radiation damage to the diodes. 2D dose distribution with and without the compensator were measured and compared with the treatment planning system (TPS) calculations. Results: The WET of the MapCHECK diode’s buildup was determined to be 1.7 cm. The MapCHECK-measured PBC were virtually identical to those measured by a parallel-plate ion chamber for 160, 180, and 250 MeV proton beams. The inverse square results of the MapCHECK were within ±0.4% of the ion chamber results. The linearity of MapCHECK results was within 1% of those from the ion chamber as measured in the range between 10 and 300 MU. All other dosimetric quantities were within 1.3% of the ion chamber results. The 2D dose distributions for non-clinical fields without compensator and the patient treatment fields with the compensator were consistent with the TPS results. The absolute dose response of the MapCHECK was changed by 7.4% after an accumulated dose increased by 170 Gy. Conclusions: The MapCHECK is a convenient and useful tool for 2D dose distribution measurements using passively

  1. A proton irradiation test facility for space research in Ankara, Turkey

    NASA Astrophysics Data System (ADS)

    Gencer, Ayşenur; Yiǧitoǧlu, Merve; Bilge Demirköz, Melahat; Efthymiopoulos, Ilias

    2016-07-01

    Space radiation often affects the electronic components' performance during the mission duration. In order to ensure reliable performance, the components must be tested to at least the expected dose that will be received in space, before the mission. Accelerator facilities are widely used for such irradiation tests around the world. Turkish Atomic Energy Authority (TAEA) has a 15MeV to 30MeV variable proton cyclotron in Ankara and the facility's main purpose is to produce radioisotopes in three different rooms for different target systems. There is also an R&D room which can be used for research purposes. This paper will detail the design and current state of the construction of a beamline to perform Single Event Effect (SEE) tests in Ankara for the first time. ESA ESCC No.25100 Standard Single Event Effect Test Method and Guidelines is being considered for these SEE tests. The proton beam kinetic energy must be between 20MeV and 200MeV according to the standard. While the proton energy is suitable for SEE tests, the beam size must be 15.40cm x 21.55cm and the flux must be between 10 ^{5} p/cm ^{2}/s to at least 10 ^{8} p/cm ^{2}/s according to the standard. The beam size at the entrance of the R&D room is mm-sized and the current is variable between 10μA and 1.2mA. Therefore, a defocusing beam line has been designed to enlarge the beam size and reduce the flux value. The beam line has quadrupole magnets to enlarge the beam size and the collimators and scattering foils are used for flux reduction. This facility will provide proton fluxes between 10 ^{7} p/cm ^{2}/s and 10 ^{10} p/cm ^{2}/s for the area defined in the standard when completed. Also for testing solar cells developed for space, the proton beam energy will be lowered below 10MeV. This project has been funded by Ministry of Development in Turkey and the beam line construction will finish in two years and SEE tests will be performed for the first time in Turkey.

  2. Hydrogen release from 800 MeV proton-irradiated tungsten

    NASA Astrophysics Data System (ADS)

    Oliver, B. M.; Venhaus, T. J.; Causey, R. A.; Garner, F. A.; Maloy, S. A.

    2002-12-01

    Tungsten irradiated in spallation neutron sources, such as those proposed for the accelerator production of tritium (APT) project, will contain large quantities of generated helium and hydrogen gas. Tungsten used in proposed fusion reactors will also be exposed to neutrons, and the generated protium will be accompanied by deuterium and tritium diffusing in from the plasma-facing surface. The release kinetics of these gases during various off-normal scenarios involving loss of coolant and after heat-induced rises in temperature are of particular interest for both applications. To determine the release kinetics of hydrogen from tungsten, tungsten rods irradiated with 800 MeV protons in the Los Alamos Neutron Science Center (LANSCE) to high exposures as part of the APT project have been examined. Hydrogen evolution from the tungsten has been measured using a dedicated mass-spectrometer system by subjecting the specimens to an essentially linear temperature ramp from ˜300 to ˜1500 K. Release profiles are compared with predictions obtained using the Tritium Migration Analysis Program (TMAP4). The measurements show that for high proton doses, the majority of the hydrogen is released gradually, starting at about 900 K and reaching a maximum at about 1400 K, where it drops fairly rapidly. Comparisons with TMAP show quite reasonable agreement using a trap energy of 1.4 eV and a trap density of ˜7%. There is a small additional release fraction occurring at ˜550 K, which is believed to be associated with low-energy trapping at or near the surface, and, therefore, was not included in the bulk TMAP model.

  3. Changes in luminescence emission induced by proton irradiation: InGaAs/GaAs quantum wells and quantum dots

    NASA Technical Reports Server (NTRS)

    Leon, R.; Swift, G. M.; Magness, B.; Taylor, W. A.; Tang, Y. S.; Wang, K. L.; Dowd, P.; Zhang, Y. H.

    2000-01-01

    The photoluminescence emission from InGaAs/GaAs quantum-well and quantum-dot (QD) structures are compared after controlled irradiation with 1.5 MeV proton fluxes. Results presented here show a significant enhancement in radiation tolerance with three-dimensional quantum confinement.

  4. A Comparison of Model Calculation and Measurement of Absorbed Dose for Proton Irradiation. Chapter 5

    NASA Technical Reports Server (NTRS)

    Zapp, N.; Semones, E.; Saganti, P.; Cucinotta, F.

    2003-01-01

    With the increase in the amount of time spent EVA that is necessary to complete the construction and subsequent maintenance of ISS, it will become increasingly important for ground support personnel to accurately characterize the radiation exposures incurred by EVA crewmembers. Since exposure measurements cannot be taken within the organs of interest, it is necessary to estimate these exposures by calculation. To validate the methods and tools used to develop these estimates, it is necessary to model experiments performed in a controlled environment. This work is such an effort. A human phantom was outfitted with detector equipment and then placed in American EMU and Orlan-M EVA space suits. The suited phantom was irradiated at the LLUPTF with proton beams of known energies. Absorbed dose measurements were made by the spaceflight operational dosimetrist from JSC at multiple sites in the skin, eye, brain, stomach, and small intestine locations in the phantom. These exposures are then modeled using the BRYNTRN radiation transport code developed at the NASA Langley Research Center, and the CAM (computerized anatomical male) human geometry model of Billings and Yucker. Comparisons of absorbed dose calculations with measurements show excellent agreement. This suggests that there is reason to be confident in the ability of both the transport code and the human body model to estimate proton exposure in ground-based laboratory experiments.

  5. The formation of shallow-donor distribution profiles in proton irradiation of silicon

    NASA Astrophysics Data System (ADS)

    Grekhov, I. V.; Kostina, L. S.; Lomasov, V. N.; Yusupova, Sh. A.; Belyakova, E. I.

    2014-12-01

    A study of the formation of shallow hydrogen-containing donors (hydrogen-related shallow thermal donors, STD(H)) in silicon under proton irradiation followed by annealing in a temperature range of 300-500°C is reported. The effect of postimplantation annealing regimes on the concentration distribution of shallow donors at various proton energies and fluences is examined. It is shown that the shape of the concentration profiles strongly varies with temperature and annealing duration when a fixed concentration of radiation defects is introduced and equally with energy and dose at a given annealing temperature. It is also shown that the process in which hydrogen-containing shallow donors are formed is accompanied by the appearance in n-type silicon of H-induced buried n'-layers, the formation of which near the pn junction in the high-resistivity n-base of diode structures allows the breakdown voltage of high-voltage pn junctions to be controlled. In the general case, this makes it possible to improve the characteristics of power silicon devices of various purposes.

  6. SU-D-304-02: Magnetically Focused Proton Irradiation of Small Field Targets

    SciTech Connect

    McAuley, GA; Slater, JM; Slater, JD; Wroe, AJ

    2015-06-15

    Purpose: To investigate the use of magnetic focusing for small field proton irradiations. It is hypothesized that magnetic focusing will provide significant dose distribution benefits over standard collimated beams for fields less than 10 mm diameter. Methods: Magnets consisting of 24 segments of radiation hard samarium-cobalt adhered into hollow cylinders were designed and manufactured. Two focusing magnets were placed on a positioning track on our Gantry 1 treatment table. Proton beams with energies of 127 and 157 MeV, 15 and 30 mm modulation, and 8 mm initial diameters were delivered to a water tank using single-stage scattering. Depth dose distributions were measured using a PTW PR60020 diode detector and transverse profiles were measured with Gafchromic EBT3 film. Monte Carlo simulations were also performed - both for comparison with experimental data and to further explore the potential of magnetic focusing in silica. For example, beam spot areas (based on the 90% dose contour) were matched at Bragg depth between simulated 100 MeV collimated beams and simulated beams focused by two 400 T/m gradient magnets. Results: Preliminary experimental results show 23% higher peak to entrance dose ratios and flatter spread out Bragg peak plateaus for 8 mm focused beams compared with uncollimated beams. Monte Carlo simulations showed 21% larger peak to entrance ratios and a ∼9 fold more efficient dose to target delivery compared to spot-sized matched collimated beams. Our latest results will be presented. Conclusion: Our results suggest that rare earth focusing magnet assemblies could reduce skin dose and beam number while delivering dose to nominally spherical radiosurgery targets over a much shorter time compared to unfocused beams. Immediate clinical applications include those associated with proton radiosurgery and functional radiosurgery of the brain and spine, however expanded treatment sites can be also envisaged.

  7. Proton Irradiation Sensitizes Radioresistant Non-small Cell Lung Cancer Cells by Modulating Epidermal Growth Factor Receptor-mediated DNA Repair.

    PubMed

    Park, Hyung Ju; Oh, Jeong Su; Chang, Jong Wook; Hwang, Sang-Gu; Kim, Jae-Sung

    2016-01-01

    Although proton radiotherapy is effective in treating various types of cancer, little is known on the biological responses triggered by proton irradiation. In the present study, we investigated protein profiles following proton irradiation of non-small cell lung cancer (NSCLC) cells and defined the role of proton-induced epidermal growth factor receptor (EGFR) expression in NSCLC cells. We found that proton irradiation more effectively sensitized NSCLC cells than gamma irradiation did. The expression profiles of radiosensitive and radioresistant NSCLC cells following proton and gamma irradiation were examined using antibody arrays. With regard to proteins, expression of EGFR was the most highly induced by proton irradiation. In addition, we found that EGFR inhibition with gefinitib significantly increased the radiosensitivity of NSCLC cells, and that increased radiosensitivity due to gefinitib was mediated by the suppression of DNA repair in radioresistant NSCLC cells. Thus, our data provide the first evidence that proton irradiation sensitizes radioresistant NSCLC cancer cells by modulating EGFR-mediated DNA repair.

  8. Near monochromatic 20 Me V proton acceleration using fs laser irradiating Au foils in target normal sheath acceleration regime

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Cutroneo, M.; Ceccio, G.; Cannavò, A.; Batani, D.; Boutoux, G.; Jakubowska, K.; Ducret, J. E.

    2016-04-01

    A 200 mJ laser pulse energy, 39 fs-pulse duration, 10 μm focal spot, p-polarized radiation has been employed to irradiate thin Au foils to produce proton acceleration in the forward direction. Gold foils were employed to produce high density relativistic electrons emission in the forward direction to generate a high electric field driving the ion acceleration. Measurements were performed by changing the focal position in respect of the target surface. Proton acceleration was monitored using fast SiC detectors in time-of-flight configuration. A high proton energy, up to about 20 Me V, with a narrow energy distribution, was obtained in particular conditions depending on the laser parameters, the irradiation conditions, and a target optimization.

  9. [Effect of proton irradiation of the hypophysis on its gonadotropic and thyrotropic functions in patients with prolactinoma].

    PubMed

    Isakov, A V; Konnov, B A; Potin, V V; Svechnikova, F A; Tkachenko, N N

    1988-01-01

    In order to study the effect of proton beam irradiation on prolactinoma cells and hypophyseal intact cells tests with i.v. administration of TRH (200 micrograms) and LH-RH (100 micrograms) were performed in 16 women with prolactin-secreting adenomas before and in 2 mos.-2 years after irradiation of the pituitary body with a high energy narrow proton beam (1000 MeV) at a dose of 40-120 Gy. A curative therapeutic effect of proton therapy which was low with respect to reproductive function recovery, was combined with lowered functional reserves of hypophyseal thyrotrophs and gonadotrophs. The informative value of the tests with the releasing hormones was shown for the determination of damage of hypophyseal intact cells. The results suggest refractivity of adenomatous lactotrophs to radiation exposure and the hypothalamic level of disorder of ovarian function regulation in this pathology.

  10. The temperature dependence of void and bubble formation and growth in aluminium during 600 MeV proton irradiation

    NASA Astrophysics Data System (ADS)

    Victoria, M.; Green, W. V.; Singh, B. N.; Leffers, T.

    1984-05-01

    As a part of a continuing program, we report in the present paper results obtained from irradiating pure aluminium samples in the PIREX facility installed in the 600 MeV proton beam of the accelerator at the Swiss Institute for Nuclear Research (SIN). The aluminium foils have been irradiated at 8 different temperatures in the range from 130°-430°C, to displacement doses of up to 5 dpa and helium contents of over 1000 appm. The TEM examinations have shown that at all irradiation temperatures and displacement doses, helium bubbles are formed uniformly through the whole grain interior. No voids are observed at temperatures above 160° C. At all temperatures, irradiation induced dislocations have been observed, most of them linked to bubbles. At higher temperatures and doses, clear evidence of irradiation induced precipitation has been observed; the precipitates are normally decorated with helium bubbles.

  11. Axillary irradiation omitting axillary dissection in breast cancer: is there a role for shoulder-sparing proton therapy?

    PubMed Central

    Deidda, M A; Amichetti, M

    2015-01-01

    The recent EORTC 10981-22023 AMAROS trial showed that axillary radiotherapy and axillary lymph node dissection provide comparable local control and reduced lymphoedema in the irradiated group. However, no significant differences between the two groups in range of motion and quality of life were reported. It has been acknowledged that axillary irradiation could have induced some toxicity, particularly shoulder function impairment. In fact, conventional breast irradiation by tangential beams has to be modified to achieve full-dose coverage of the axillary nodes, including in the treatment field a larger portion of the shoulder structures. In this scenario, alternative irradiation techniques were discussed. Compared with modern photon techniques, axillary irradiation by proton therapy has the potential for sparing the shoulder without detrimental increase of the medium-to-low doses to the other normal tissues. PMID:26153903

  12. Axillary irradiation omitting axillary dissection in breast cancer: is there a role for shoulder-sparing proton therapy?

    PubMed

    Farace, P; Deidda, M A; Amichetti, M

    2015-10-01

    The recent EORTC 10981-22023 AMAROS trial showed that axillary radiotherapy and axillary lymph node dissection provide comparable local control and reduced lymphoedema in the irradiated group. However, no significant differences between the two groups in range of motion and quality of life were reported. It has been acknowledged that axillary irradiation could have induced some toxicity, particularly shoulder function impairment. In fact, conventional breast irradiation by tangential beams has to be modified to achieve full-dose coverage of the axillary nodes, including in the treatment field a larger portion of the shoulder structures. In this scenario, alternative irradiation techniques were discussed. Compared with modern photon techniques, axillary irradiation by proton therapy has the potential for sparing the shoulder without detrimental increase of the medium-to-low doses to the other normal tissues. PMID:26153903

  13. Results of 1 MeV proton irradiation of front and back surfaces of silicon solar cells

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Kachare, R.; Weizer, V. G.

    1987-01-01

    Several silicon solar cells with and without back surface fields (BSF), having thicknesses of 200 microns and 63 microns were irradiated with 1 MeV protons having fluences between 1 times 10 to the 10th power and 1 times 10 to the 12th power p/square cm. The irradiation was performed using both normal and isotropic incidence on the front as well as back surfaces of the solar cells. The results of the back surface irradiations are analyzed using a model in which irradiation induced defects across the high-low (BSF) junction are considered. It is concluded that degradation of the high-low junction is responsible for the severe performance loss in thinner cells when irradiated from the rear.

  14. Study of crosslinking onset and hydrogen annealing of ultra-high molecular weight polyethylene irradiated with high-energy protons

    NASA Astrophysics Data System (ADS)

    Wilson, John Ford

    1997-09-01

    Ultra high molecular weight polyethylene (UHMW-PE) is used extensively in hip and knee endoprostheses. Radiation damage from the sterilization of these endoprostheses prior to surgical insertion results in polymer crosslinking and decreased oxidative stability. The motivation for this study was to determine if UHMW-PE could be crosslinked by low dose proton irradiation with minimal radiation damage and its subsequent deleterious effects. I found that low dose proton irradiation and post irradiation hydrogen annealing did crosslink UHMW-PE and limit post irradiation oxidation. Crosslinking onset was investigated for UHMW-PE irradiated with 2.6 and 30 MeV H+ ions at low doses from 5.7 × 1011-2.3 × 1014 ions/cm2. Crosslinking was determined from gel permeation chromatography (GPC) of 1,2,4 trichlorobenzene sol fractions and increased with dose. Fourier transform infrared spectroscopy (FTIR) showed irradiation resulted in increased free radicals confirmed from increased carbonyl groups. Radiation damage, especially at the highest doses observed, also showed up in carbon double bonds and increased methyl end groups. Hydrogen annealing after ion irradiation resulted in 40- 50% decrease in FTIR absorption associated with carbonyl. The hydrogen annealing prevented further oxidation after aging for 1024 hours at 80oC. Hydrogen annealing was successful in healing radiation damage through reacting with the free radicals generated during proton irradiation. Polyethylenes, polyesters, and polyamides are used in diverse applications by the medical profession in the treatment of orthopedic impairments and cardiovascular disease and for neural implants. These artificial implants are sterilized with gamma irradiation prior to surgery and the resulting radiation damage can lead to accelerated deterioration of the implant properties. The findings in this study will greatly impact the continued use of these materials through the elimination of many problems associated with radiation

  15. Production of 230U/226Th for targeted alpha therapy via proton irradiation of 231Pa.

    PubMed

    Morgenstern, Alfred; Lebeda, Ondrej; Stursa, Jan; Bruchertseifer, Frank; Capote, Roberto; McGinley, John; Rasmussen, Gert; Sin, Mihaela; Zielinska, Barbara; Apostolidis, Christos

    2008-11-15

    (230)U and its daughter nuclide (226)Th are novel therapeutic nuclides for application in targeted alpha-therapy of cancer. We have investigated the feasibility of producing (230)U/(226)Th via proton irradiation of (231)Pa according to the reaction (231)Pa(p,2n)(230)U. The experimental excitation function for this reaction is reported for the first time. Cross sections were measured using thin targets of (231)Pa prepared by electrodeposition and (230)U yields were analyzed using alpha-spectrometry. Beam parameters (energy and intensity) were determined both by calculation using a mathematical model based on measured beam orbits and beam current integrator and by parallel monitor reactions on copper foils using high-resolution gamma-spectrometry and IAEA recommended cross-section data. The measured cross sections are in good agreement with model calculations using the EMPIRE-II code and are sufficiently high for the production of (230)U/(226)Th in clinically relevant amounts. A highly effective separation process was developed to isolate clinical grade (230)U from irradiated protactinium oxide targets. Product purity was assessed using alpha- and gamma-spectrometry as well as ICPMS.

  16. Production of 230U/226Th for targeted alpha therapy via proton irradiation of 231Pa.

    PubMed

    Morgenstern, Alfred; Lebeda, Ondrej; Stursa, Jan; Bruchertseifer, Frank; Capote, Roberto; McGinley, John; Rasmussen, Gert; Sin, Mihaela; Zielinska, Barbara; Apostolidis, Christos

    2008-11-15

    (230)U and its daughter nuclide (226)Th are novel therapeutic nuclides for application in targeted alpha-therapy of cancer. We have investigated the feasibility of producing (230)U/(226)Th via proton irradiation of (231)Pa according to the reaction (231)Pa(p,2n)(230)U. The experimental excitation function for this reaction is reported for the first time. Cross sections were measured using thin targets of (231)Pa prepared by electrodeposition and (230)U yields were analyzed using alpha-spectrometry. Beam parameters (energy and intensity) were determined both by calculation using a mathematical model based on measured beam orbits and beam current integrator and by parallel monitor reactions on copper foils using high-resolution gamma-spectrometry and IAEA recommended cross-section data. The measured cross sections are in good agreement with model calculations using the EMPIRE-II code and are sufficiently high for the production of (230)U/(226)Th in clinically relevant amounts. A highly effective separation process was developed to isolate clinical grade (230)U from irradiated protactinium oxide targets. Product purity was assessed using alpha- and gamma-spectrometry as well as ICPMS. PMID:18925748

  17. Proton-associated alpha-irradiation in the early solar system - A possible K-41 anomaly

    NASA Technical Reports Server (NTRS)

    Dwek, E.

    1978-01-01

    It is shown that alpha-particle fluences associated with proton fluences sufficiently high to produce the Al-correlated excess of Mg-26 found in the Allende meteorite produce equally significant amounts of Ca-41. The Ca-41 is produced by Ar-38(alpha,n)Ca-41 reactions occurring in the gas and condenses into the Ca-Al-rich grains forming at that time. After the decay of Ca-41, these grains will have a Ca-correlated excess of K-41. The question is considered whether the proposed scheme is capable of producing an observable excess of K-41. A calculation is conducted of the magnitude of the K-41 excess expected to be found in Ca-Al-rich grains for various ratios of Ca/K by developing an irradiation-condensation model. It is shown that on the basis of the currently available data it is not possible to come to firm conclusions regarding the validity of the irradiation model.

  18. Energy related germination and survival rates of water-imbibed Arabidopsis seeds irradiated with protons

    NASA Astrophysics Data System (ADS)

    Qin, H. L.; Xue, J. M.; Lai, J. N.; Wang, J. Y.; Zhang, W. M.; Miao, Q.; Yan, S.; Zhao, W. J.; He, F.; Gu, H. Y.; Wang, Y. G.

    2006-04-01

    In order to investigate the influence of ion energy on the germination and survival rates, water-imbibed Arabidopsis seeds were irradiated with protons in atmosphere. The ion fluence used in this experiment was in the range of 4 × 109-1 × 1014 ions/cm2. The ion energy is from 1.1 MeV to 6.5 MeV. According to the structure of the seed and TRIM simulation, the ions with the energy of 6.5 MeV can irradiate the shoot apical meristem directly whereas the ions with the energy of 1.1 MeV cannot. The results showed that both the germination and survival rates decrease while increasing the ion fluence, and the fluence-respond curve for each energy has different character. Besides the shoot apical meristem (SAM), which is generally considered as the main radiobiological target, the existence of a secondary target around SAM is proposed in this paper.

  19. Dosimetric comparison of proton and photon three-dimensional, conformal, external beam accelerated partial breast irradiation techniques

    SciTech Connect

    Kozak, Kevin R.; Katz, Angela; Adams, Judith C.; Crowley, Elizabeth M.; Nyamwanda, Jacqueline A.C.; Feng, Jennifer K.C.; Doppke, Karen P.; DeLaney, Thomas F.; Taghian, Alphonse G. . E-mail: ataghian@partners.org

    2006-08-01

    Purpose: To compare the dosimetry of proton and photon-electron three-dimensional, conformal, external beam accelerated partial breast irradiation (3D-CPBI). Methods and Materials: Twenty-four patients with fully excised, Stage I breast cancer treated with adjuvant proton 3D-CPBI had treatment plans generated using the mixed-modality, photon-electron 3D-CPBI technique. To facilitate dosimetric comparisons, planning target volumes (PTVs; lumpectomy site plus 1.5-2.0 cm margin) and prescribed dose (32 Gy) were held constant. Plans were optimized for PTV coverage and normal tissue sparing. Results: Proton and mixed-modality plans both provided acceptable PTV coverage with 95% of the PTV receiving 90% of the prescribed dose in all cases. Both techniques also provided excellent dose homogeneity with a dose maximum exceeding 110% of the prescribed dose in only one case. Proton 3D-CPBI reduced the volume of nontarget breast tissue receiving 50% of the prescribed dose by an average of 36%. Statistically significant reductions in the volume of total ipsilateral breast receiving 100%, 75%, 50%, and 25% of the prescribed dose were also observed. The use of protons resulted in small, but statistically significant, reductions in the radiation dose delivered to 5%, 10%, and 20% of ipsilateral and contralateral lung and heart. The nontarget breast tissue dosimetric advantages of proton 3D-CPBI were not dependent on tumor location, breast size, PTV size, or the ratio of PTV to breast volume. Conclusions: Compared to photon-electron 3D-CPBI, proton 3D-CPBI significantly reduces the volume of irradiated nontarget breast tissue. Both approaches to accelerated partial breast irradiation offer exceptional lung and heart sparing.

  20. Use of primary cell cultures to measure the late effects in the skins of rhesus monkeys irradiated with protons

    NASA Astrophysics Data System (ADS)

    Cox, A. B.; Wood, D. H.; Lett, J. T.

    Previous pilot investigations of the uses of primary cell cultures to study late damage in stem cells of the skin of the New Zealand white (NZW) rabbit and the rhesus monkey /1-3/, have been extended to individual monkeys exposed to 55 MeV protons. Protons of this energy have a larger range in tissue of (~2.6 cm) than the 32 MeV protons (~0.9 cm) to which the animals in our earlier studies had been exposed. Although the primary emphases in the current studies were improvement and simplification in the techniques and logistics of transportation of biopsies to a central analytical facility, comparison of the quantitative measurements obtained thus far for survival of stem cells in the skins from animals irradiated 21 years ago reveals that the effects of both proton energies are similar.

  1. A priming dose of protons alters the early cardiac cellular and molecular response to 56Fe irradiation

    NASA Astrophysics Data System (ADS)

    Ramadan, Samy S.; Sridharan, Vijayalakshmi; Koturbash, Igor; Miousse, Isabelle R.; Hauer-Jensen, Martin; Nelson, Gregory A.; Boerma, Marjan

    2016-02-01

    Purpose: Recent evidence suggests that the heart may be injured by ionizing radiation at lower doses than was previously thought. This raises concerns about the cardiovascular risks from exposure to radiation during space travel. Since space travel is associated with exposure to both protons from solar particle events and heavy ions from galactic cosmic rays, we here examined the effects of a "priming" dose of protons on the cardiac cellular and molecular response to a "challenge" dose of 56Fe in a mouse model. Methods: Male C57BL/6 mice at 10 weeks of age were exposed to sham-irradiation, 0.1 Gy of protons (150 MeV), 0.5 Gy of 56Fe (600 MeV/n), or 0.1 Gy of protons 24 hours prior to 0.5 Gy of 56Fe. Hearts were obtained at 7 days post-irradiation and western-blots were used to determine protein markers of cardiac remodeling, inflammatory infiltration, and cell death. Results: Exposure to 56Fe caused an increase in expression of α-smooth muscle cell actin, collagen type III, the inflammatory cell markers mast cell tryptase, CD2 and CD68, the endothelial glycoprotein thrombomodulin, and cleaved caspase 3. Of all proteins investigated, protons at a dose of 0.1 Gy induced a small increase only in cleaved caspase 3 levels. On the other hand, exposure to protons 24 hours before 56Fe prevented all of the responses to 56Fe. Conclusions: This study shows that a low dose of protons may prime the heart to respond differently to a subsequent challenge dose of heavy ions. Further investigation is required to identify responses at additional time points, consequences for cardiac function, threshold dose levels, and mechanisms by which a proton priming dose may alter the response to heavy ions.

  2. The Low Temperature Microgravity Physics Facility Project

    NASA Technical Reports Server (NTRS)

    Chui, T.; Holmes, W.; Lai, A.; Croonquist, A.; Eraker, J.; Abbott, R.; Mills, G.; Mohl, J.; Craig, J.; Balachandra, B.; Gannon, J.

    2000-01-01

    We describe the design and development of the Low Temperature Microgravity Physics Facility, which is intended to provide a unique environment of low temperature and microgravity for the scientists to perform breakthrough investigations on board the International Space Station.

  3. Frequency of Early and Late Chromosome Aberrations in Different Types of Cells After Proton and Fe Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Lu, Tao; Wu, Honglu; Zhang, Ye; Yeshitla, Samrawit; Kadhim, Munira; Wilson, Bobby; Bowler, Deborah

    2016-07-01

    DNA damages induced by space radiation, consisting of protons and high-LET charged particles, can be complex in nature, which are often left unrepaired and cause chromosomal aberrations. Increased level of genomic instability is attributed to tumorigenesis and increased cancer risks. To investigate genomic instability induced by charged particles, human lymphocytes ex vivo, human fibroblasts, and human mammary epithelial cells, as well as mouse bone marrow stem cells isolated from CBA/CaH and C57BL/6 strains were exposed to high energy protons and Fe ions. Metaphase chromosome spreads at different cell divisions after radiation exposure were collected and, chromosome aberrations were analyzed with fluorescence in situ hybridization with whole chromosome-specific probes for human cells. With proton irradiation, levels of chromosome aberrations decreased by about 50% in both lymphocytes and epithelial cells after multiple cell divisions, compared to initial chromosome aberrations at 48 hours post irradiation in both cell types. With Fe ion irradiation, however, the frequency of chromosome aberrations in lymphocytes after multiple cell divisions was significantly lower than that in epithelial cells at comparable cell divisions, while their initial chromosome aberrations were at similar levels. Similar to the human cells, after Fe ion irradiation, the frequency of late chromosome aberrations was similar to that of the early damages for radio-sensitive CBA cells, but different for radio-resistant C57 cells. Our results suggest that relative biological effectiveness (RBE) values are dependent not only on radiation sources, but also on cell types and cell divisions.

  4. Frequency of Early and Late Chromosome Aberrations in Different Types of Cells After Proton and Fe Ion Irradiation

    NASA Technical Reports Server (NTRS)

    Lu, Tao; Zhang, Ye; Yeshitla, Samrawit; Bowler, Deborah; Kadhim, Munira; Wilson, Bobby; Wu, Honglu

    2016-01-01

    DNA damages induced by space radiation, consisting of protons and high-LET charged particles, can be complex in nature, which are often left unrepaired and cause chromosomal aberrations. Increased level of genomic instability is attributed to tumorigenesis and increased cancer risks. To investigate genomic instability induced by charged particles, human lymphocytes ex vivo, human fibroblasts, and human mammary epithelial cells, as well as mouse bone marrow stem cells isolated from CBA/CaH and C57BL/6 strains were exposed to high energy protons and Fe ions. Metaphase chromosome spreads at different cell divisions after radiation exposure were collected and, chromosome aberrations were analyzed with fluorescence in situ hybridization with whole chromosome-specific probes for human cells. With proton irradiation, levels of chromosome aberrations decreased by about 50% in both lymphocytes and epithelial cells after multiple cell divisions, compared to initial chromosome aberrations at 48 hours post irradiation in both cell types. With Fe ion irradiation, however, the frequency of chromosome aberrations in lymphocytes after multiple cell divisions was significantly lower than that in epithelial cells at comparable cell divisions, while their initial chromosome aberrations were at similar levels. Similar to the human cells, after Fe ion irradiation, the frequency of late chromosome aberrations was similar to that of the early damages for radio-sensitive CBA cells, but different for radio-resistant C57 cells. Our results suggest that relative biological effectiveness (RBE) values are dependent not only on radiation sources, but also on cell types and cell divisions.

  5. Repair rates of DNA double-strand breaks under different doses of proton and γ-ray irradiation

    NASA Astrophysics Data System (ADS)

    Wu, Jingwen; Fu, Qibin; Quan, Yi; Wang, Weikang; Mei, Tao; Li, Jia; Yang, Gen; Ren, Xiaotang; Xue, Jianming; Wang, Yugang

    2012-04-01

    It is known that DNA double-strand breaks (DSBs), which can be induced by a variety of treatments including ionizing radiation (IR), can cause most deleterious consequences among all kinds of DNA lesions. However, it is still under debate about whether DSBs repair is equally efficient after low and high-LET radiation, especially the basic biological responses after exposure to high-LET particles. In present study, synchronous fibroblast normal Human lung fibroblast (NHLF) cells were irradiated with graded doses of proton and γ-ray. Then γ-H2AX foci assay was used to monitor DSBs induction and repair at 0.5, 1, 2, 4, and 18 h post irradiation. The results showed that the γ-ray irradiation could produce more γ-H2AX foci than proton irradiation at the same dose. However, compared to low LET radiation with γ-ray, the results also showed a much slower DSBs repair rate after high LET radiation with protons, suggesting that the cellular ability to eliminate DSBs after low and high-LET ionizing radiation is quite different.

  6. Electron decoherence at low temperatures

    NASA Astrophysics Data System (ADS)

    Mohanty, Pritiraj

    2001-03-01

    Electron decoherence is fundamental to condensed matter physics. Our understanding of metals and insulators in the Fermi-liquid framework relies entirely on a diverging decoherence rate 1/τ_φ at low temperatures, which is expected to vanish at T=0. However, recent experiments find that 1/τ_φ saturates at low temperatures [1-2]. We review these measurements on a variety of mesoscopic systems (in 0D, 1D, 2D and 3D) as well as the control experiments used to check for various artifacts [1-3]. We emphasize the connection between the temperature-independent decoherence rate and persistent current in normal metals [4]. We briefly discuss decoherence induced by dynamic defects or two-level systems [5,6], including its relevance--or lack thereof---to the experiments on metallic wires [2]. Saturation of decohrence rate is argued to be present in---and relevant to---the following phenomena: metal-insulator transition in 2D [7,8], superconductor-insulator transition in 2D [9], quantum-Hall-insulator transition [10], transport through superconductor/normal-metal hybrid junctions [11], normal-state resistivity of high Tc superconductors [12], persistent current in normal metals [4], and energy relaxation in normal metals [13]. [1] P. Mohanty, Physica B 280, 446 (2000). [2] P. Mohanty, E.M.Q. Jariwala, R. Webb, PRL 78, 3366 (1997); PRB 55, R13542 (1997). [3] P. Mohanty, R. Webb, PRL 84, 4481 (2000). [4] P. Mohanty, Ann. Phys. 8, 549 (1999). [5] P. Mohanty, M.L. Roukes (to be published). [6] K. Ahn, P. Mohanty, cond-mat/ 0011139. [7] S. Kravchenko et al. PRB 50, 8039 (1994). [8] G. Brunthaler, A. Prinz, G. Bauer, V. Pudalov, cond-mat/0007230. [9] A. Kapitulnik, N. Mason, S. Kivelson, S. Chakravarty, cond-mat/0008005. [10] D. Shahar, D. Tsui, M. Shayegan, J. Cunningham, E. Shimsoni, S. Sondhi, SSC. 102, 817 (1997). [11] A. Vaknin, A. Frydman, Z. Ovadyahu, PRB 61, 13037 (2000). [12] P. Fournier et al., PRB 62, R11993 (2000). [13] A. Gougam, F. Pierre, H. Pothier, D. Esteve, N

  7. SU-E-T-533: LET Dependence Correction of Radiochromic Films for Application in Low Energy Proton Irradiation

    SciTech Connect

    Reinhardt, S; Wuerl, M; Assmann, W; Parodi, K; Greubel, C; Wilkens, J; Hillbrand, M; Mairani, A

    2015-06-15

    Purpose: Many cell irradiation experiments with low-energy laser-driven ions rely on radiochromic films (RCF), because of their dose-rate independent response and superior spatial resolution. RCF dosimetry in low-energy ion beams requires a correction of the LET dependent film response. The relative efficiency (RE), the ratio of photon to proton dose that yields the same film darkening, is a measure for the film’s LET dependence. A direct way of RE determination is RCF irradiation with low-energy mono-energetic protons and hence, well-defined LET. However, RE is usually determined using high energy proton depth dose measurements where RE corrections require knowledge of the average LET in each depth, which can be either track (tLET) or dose (dLET) averaged. The appropriate LET concept has to be applied to allow a proper film response correction. Methods: Radiochromic EBT2 and EBT3 films were irradiated in clinical photon and proton beams. For each depth of the 200 MeV proton depth dose curve, tLET and dLET were calculated by special user routines from the Monte Carlo code FLUKA. Additional irradiations with mono-energetic low energy protons (4–20 MeV) serve as reference for the RE determination. Results: The difference of dLET and tLET increases with depth, with the dLET being almost twice as large as the tLET for the maximum depth. The comparison with mono-energetic measurements shows a good agreement of the RE for the dLET concept, while a considerably steeper drop in RE is observed when applying the tLET. Conclusion: RCF can be used as reference dosimeter for biomedical experiments with low-energy proton beams if appropriate LET corrections are applied. When using depth dose measurements from clinical proton accelerators for these corrections, the concept of dLET has to be applied. Acknowledgement: This work was funded by the DFG Cluster of Excellence ‘Munich-Centre for Advanced Photonics’ (MAP). This work was funded by the DFG Cluster of Excellence

  8. Accelerated partial-breast irradiation using intensity-modulated proton radiotherapy: do uncertainties outweigh potential benefits?

    PubMed Central

    Wang, X; Zhang, X; Li, X; Amos, R A; Shaitelman, S F; Hoffman, K; Howell, R; Salehpour, M; Zhang, S X; Sun, T L; Smith, B; Tereffe, W; Perkins, G H; Buchholz, T A; Strom, E A

    2013-01-01

    Objective: Passive scattering proton beam (PSPB) radiotherapy for accelerated partial-breast irradiation (APBI) provides superior dosimetry for APBI three-dimensional conformal photon radiotherapy (3DCRT). Here we examine the potential incremental benefit of intensity-modulated proton radiotherapy (IMPT) for APBI and compare its dosimetry with PSPB and 3DCRT. Methods: Two theoretical IMPT plans, TANGENT_PAIR and TANGENT_ENFACE, were created for 11 patients previously treated with 3DCRT APBI and were compared with PSPB and 3DCRT plans for the same CT data sets. The impact of range, motion and set-up uncertainties as well as scanned spot mismatching between fields of IMPT plans was evaluated. Results: IMPT plans for APBI were significantly better regarding breast skin sparing (p<0.005) and other normal tissue sparing than 3DCRT plans (p<0.01) with comparable target coverage (p=ns). IMPT plans were statistically better than PSPB plans regarding breast skin (p<0.002) and non-target breast (p<0.007) in higher dose regions but worse or comparable in lower dose regions. IMPT plans using TANGENT_ENFACE were superior to that using TANGENT_PAIR in terms of target coverage (p<0.003) and normal tissue sparing (p<0.05) in low-dose regions. IMPT uncertainties were demonstrated for multiple causes. Qualitative comparison of dose–volume histogram confidence intervals for IMPT suggests that numeric gains may be offset by IMPT uncertainties. Conclusion: Using current clinical dosimetry, PSPB provides excellent dosimetry compared with 3DCRT with fewer uncertainties compared with IMPT. Advances in knowledge: As currently delivered in the clinic, PSPB planning for APBI provides as good or better dosimetry than IMPT with less uncertainty. PMID:23728947

  9. SU-E-T-337: Treatment Planning Study of Craniospinal Irradiation with Spot Scanning Proton Therapy

    SciTech Connect

    Tasson, A; Beltran, C; Laack, N; Childs, S; Tryggestad, E; Whitaker, T

    2014-06-01

    Purpose: To develop a treatment planning technique that achieves optimal robustness against systematic position and range uncertainties, and interfield position errors for craniospinal irradiation (CSI) using spot scanning proton radiotherapy. Methods: Eighteen CSI patients who had previously been treated using photon radiation were used for this study. Eight patients were less than 10 years old. The prescription dose was 23.4Gy in 1.8Gy fractions. Two different field arrangement types were investigated: 1 posterior field per isocenter and 2 posterior oblique fields per isocenter. For each field type, two delivery configurations were used: 5cm bolus attached to the treatment table and a 4.5cm range shifter located inside the nozzle. The target for each plan was the whole brain and thecal sac. For children under the age of 10, all plan types were repeated with an additional dose of 21Gy prescribed to the vertebral bodies. Treatment fields were matched by stepping down the dose in 10% increments over 9cm. Robustness against 3% and 3mm uncertainties, as well as a 3mm inter-field error was analyzed. Dose coverage of the target and critical structure sparing for each plan type will be considered. Ease of planning and treatment delivery was also considered for each plan type. Results: The mean dose volume histograms show that the bolus plan with posterior beams gave the best overall plan, and all proton plans were comparable to or better than the photon plans. The plan type that was the most robust against the imposed uncertainties was also the bolus plan with posterior beams. This is also the plan configuration that is the easiest to deliver and plan. Conclusion: The bolus plan with posterior beams achieved optimal robustness against systematic position and range uncertainties, as well as inter-field position errors.

  10. Effects of proton irradiation on single-stranded DNA studied by using X-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, E.; Lee, Cheol Eui; Han, J. H.

    2016-08-01

    X-ray photoelectron spectroscopy (XPS) has been employed in order to study the effects of proton irradiation on herring sperm single-stranded DNA. Systematic changes of the chemical shifts in the C, N, O, and P XPS line components as functions of the irradiation dose were observed, indicative of the bonding configurations in the DNA system. While the C 1 s XPS lines showed weak blueshifts, the N 1 s, O 1 s, and P 2 p XPS lines showed blueshifts with a marked dependence on the irradiation dose in a prominent manner. Our results show that linear energy transfer by charged particles and photons may have distinct molecular-level effects as the C 1 s, N 1 s, O 1 s, and P 2 p XPS lines showed redshifts in our previous study of effects of the γ-ray irradiation on the same system.

  11. Effects of very low fluences of high-energy protons or iron ions on irradiated and bystander cells.

    PubMed

    Yang, H; Magpayo, N; Rusek, A; Chiang, I-H; Sivertz, M; Held, K D

    2011-12-01

    In space, astronauts are exposed to radiation fields consisting of energetic protons and high atomic number, high-energy (HZE) particles at very low dose rates or fluences. Under these conditions, it is likely that, in addition to cells in an astronaut's body being traversed by ionizing radiation particles, unirradiated cells can also receive intercellular bystander signals from irradiated cells. Thus this study was designed to determine the dependence of DNA damage induction on dose at very low fluences of charged particles. Novel techniques to quantify particle fluence have been developed at the NASA Space Radiation Biology Laboratory (NSRL) at Brookhaven National Laboratory (BNL). The approach uses a large ionization chamber to visualize the radiation beam coupled with a scintillation counter to measure fluence. This development has allowed us to irradiate cells with 1 GeV/nucleon protons and iron ions at particle fluences as low as 200 particles/cm(2) and quantify biological responses. Our results show an increased fraction of cells with DNA damage in both the irradiated population and bystander cells sharing medium with irradiated cells after low fluences. The fraction of cells with damage, manifest as micronucleus formation and 53BP1 focus induction, is about 2-fold higher than background at doses as low as ∼0.47 mGy iron ions (∼0.02 iron ions/cell) or ∼70 μGy protons (∼2 protons/cell). In the irradiated population, irrespective of radiation type, the fraction of damaged cells is constant from the lowest damaging fluence to about 1 cGy, above which the fraction of damaged cells increases with dose. In the bystander population, the level of damage is the same as in the irradiated population up to 1 cGy, but it does not increase above that plateau level with increasing dose. The data suggest that at fluences of high-energy protons or iron ions less than about 5 cGy, the response in irradiated cell populations may be dominated by the bystander response.

  12. A Comparison of Molecular and Histopathological Changes in Mouse Intestinal Tissue Following Whole-Body Proton- or Gamma-Irradiation

    NASA Technical Reports Server (NTRS)

    Purgason, Ashley; Mangala, Lingegowda; Zhang, Ye; Hamilton, Stanley; Wu, Honglu

    2010-01-01

    There are many consequences following exposure to the space radiation environment which can adversely affect the health of a crew member. Acute radiation syndrome (ARS) involving nausea and vomiting, damage to radio-sensitive tissue such as the blood forming organs and gastrointestinal tract, and cancer are some of these negative effects. The space radiation environment is ample with protons and contains gamma rays as well. Little knowledge exists to this point, however, regarding the effects of protons on mammalian systems; conversely several studies have been performed observing the effects of gamma rays on different animal models. For the research presented here, we wish to compare our previous work looking at whole-body exposure to protons using a mouse model to our studies of mice experiencing whole-body exposure to gamma rays as part of the radio-adaptive response. Radio-adaptation is a well-documented phenomenon in which cells exposed to a priming low dose of radiation prior to a higher dose display a reduction in endpoints like chromosomal aberrations, cell death, micronucleus formation, and more when compared to their counterparts receiving high dose-irradiation only. Our group has recently completed a radio-adaptive experiment with C57BL/6 mice. For both this study and the preceding proton research, the gastrointestinal tract of each animal was dissected four hours post-irradiation and the isolated small intestinal tissue was fixed in formalin for histopathological examination or snap-frozen in liquid nitrogen for RNA isolation. Histopathologic observation of the tissue using standard H&E staining methods to screen for morphologic changes showed an increase in apoptotic lesions for even the lowest doses of 0.1 Gy of protons and 0.05 Gy of gamma rays, and the percentage of apoptotic cells increased with increasing dose. A smaller percentage of crypts showed 3 or more apoptotic lesions in animals that received 6 Gy of gamma-irradiation compared to mice

  13. Craniospinal Irradiation Techniques: A Dosimetric Comparison of Proton Beams With Standard and Advanced Photon Radiotherapy

    SciTech Connect

    Yoon, Myonggeun; Shin, Dong Ho; Kim, Jinsung; Kim, Jong Won; Kim, Dae Woong; Park, Sung Yong; Lee, Se Byeong; Kim, Joo Young; Park, Hyeon-Jin; Park, Byung Kiu; Shin, Sang Hoon

    2011-11-01

    Purpose: To evaluate the dosimetric benefits of advanced radiotherapy techniques for craniospinal irradiation in cancer in children. Methods and Materials: Craniospinal irradiation (CSI) using three-dimensional conformal radiotherapy (3D-CRT), tomotherapy (TOMO), and proton beam treatment (PBT) in the scattering mode was planned for each of 10 patients at our institution. Dosimetric benefits and organ-specific radiation-induced cancer risks were based on comparisons of dose-volume histograms (DVHs) and on the application of organ equivalent doses (OEDs), respectively. Results: When we analyzed the organ-at-risk volumes that received 30%, 60%, and 90% of the prescribed dose (PD), we found that PBT was superior to TOMO and 3D-CRT. On average, the doses delivered by PBT to the esophagus, stomach, liver, lung, pancreas, and kidney were 19.4 Gy, 0.6 Gy, 0.3 Gy, 2.5 Gy, 0.2 Gy, and 2.2 Gy for the PD of 36 Gy, respectively, which were significantly lower than the doses delivered by TOMO (22.9 Gy, 4.5 Gy, 6.1 Gy, 4.0 Gy, 13.3 Gy, and 4.9 Gy, respectively) and 3D-CRT (34.6 Gy, 3.6 Gy, 8.0 Gy, 4.6 Gy, 22.9 Gy, and 4.3 Gy, respectively). Although the average doses delivered by PBT to the chest and abdomen were significantly lower than those of 3D-CRT or TOMO, these differences were reduced in the head-and-neck region. OED calculations showed that the risk of secondary cancers in organs such as the stomach, lungs, thyroid, and pancreas was much higher when 3D-CRT or TOMO was used than when PBT was used. Conclusions: Compared with photon techniques, PBT showed improvements in most dosimetric parameters for CSI patients, with lower OEDs to organs at risk.

  14. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    SciTech Connect

    Harlan U. Anderson

    2000-03-31

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and Testing of Planar Single Cells. During this time period substantial progress has been made in developing low temperature deposition techniques to produce dense, nanocrystalline yttrium-stabilized zirconia films on both dense oxide and polymer substrates. Progress has been made in the preparation and characterization of thin electrolytes and porous LSM substrates. Both of these tasks are essentially on or ahead of schedule. In our proposal, we suggested that the ZrO{sub 2}/Sc system needed to be considered as a candidate as a thin electrolyte. This was because microcrystalline ZrO{sub 2}/Sc has a significantly higher ionic conductivity than YSZ, particularly at the lower temperatures. As a result, some 0.5 micron thick film of ZrO{sub 2}/16% Sc on an alumina substrate (grain size 20nm) was prepared and the electrical conductivity measured as a function of temperature and oxygen activity. The Sc doped ZrO{sub 2} certainly has a higher conductivity that either 20nm or 2400nm YSZ, however, electronic conductivity dominates the conductivity for oxygen activities below 10{sup -15}. Whereas for YSZ, electronic conductivity is not a problem until the oxygen activity decreases below 10{sup -25}. These initial results show that the ionic conductivity of 20nm YSZ and 20nm ZrO{sub 2}/16% Sc are essentially the same and the enhanced conductivity which is observed for Sc doping in microcrystalline specimens is not observed for the same composition when it is nanocrystalline. In addition they show that the electronic conductivity of Sc doped ZrO{sub 2} is at least two orders of magnitude higher than that observed for YSZ. The conclusion one reaches is that for 0.5 to 1 micron thick nanocrystalline films, Sc doping of ZrO{sub 2} has no benefits compared to YSZ. As a result, electrolyte films of ZrO{sub 2}/Sc should not be considered as candidates

  15. Comparison of risk of radiogenic second cancer following photon and proton craniospinal irradiation for a pediatric medulloblastoma patient

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Howell, Rebecca M.; Giebeler, Annelise; Taddei, Phillip J.; Mahajan, Anita; Newhauser, Wayne D.

    2013-02-01

    Pediatric patients who received radiation therapy are at risk of developing side effects such as radiogenic second cancer. We compared proton and photon therapies in terms of the predicted risk of second cancers for a 4 year old medulloblastoma patient receiving craniospinal irradiation (CSI). Two CSI treatment plans with 23.4 Gy or Gy (RBE) prescribed dose were computed: a three-field 6 MV photon therapy plan and a four-field proton therapy plan. The primary doses for both plans were determined using a commercial treatment planning system. Stray radiation doses for proton therapy were determined from Monte Carlo simulations, and stray radiation doses for photon therapy were determined from measured data. Dose-risk models based on the Biological Effects of Ionization Radiation VII report were used to estimate the risk of second cancer in eight tissues/organs. Baseline predictions of the relative risk for each organ were always less for proton CSI than for photon CSI at all attained ages. The total lifetime attributable risk of the incidence of second cancer considered after proton CSI was much lower than that after photon CSI, and the ratio of lifetime risk was 0.18. Uncertainty analysis revealed that the qualitative findings of this study were insensitive to any plausible changes of dose-risk models and mean radiation weighting factor for neutrons. Proton therapy confers lower predicted risk of second cancer than photon therapy for the pediatric medulloblastoma patient.

  16. Comparison of risk of radiogenic second cancer following photon and proton craniospinal irradiation for a pediatric medulloblastoma patient

    PubMed Central

    Zhang, Rui; Howell, Rebecca M; Giebeler, Annelise; Taddei, Phillip J; Mahajan, Anita; Newhauser, Wayne D

    2013-01-01

    Pediatric patients who received radiation therapy are at risk of developing side effects like radiogenic second cancer. We compared proton and photon therapies in terms of the predicted risk of second cancers for a 4-year-old medulloblastoma patient receiving craniospinal irradiation (CSI). Two CSI treatment plans with 23.4 Gy or Gy (RBE) prescribed dose were computed: a three-field 6-MV photon therapy plan and a four-field proton therapy plan. The primary doses for both plans were determined using a commercial treatment planning system. Stray radiation doses for proton therapy were determined from Monte Carlo simulations, and stray radiation doses for photon therapy were determined from measured data. Dose-risk models based on the Biological Effects of Ionization Radiation VII report were used to estimate risk of second cancer in eight tissues/organs. Baseline predictions of the relative risk for each organ were always less for proton CSI than for photon CSI at all attained ages. The total lifetime attributable risks of the incidence of second cancer considered after proton CSI and photon CSI were 7.7% and 92%, respectively, and the ratio of lifetime risk was 0.083. Uncertainty analysis revealed that the qualitative findings of this study were insensitive to any plausible changes of dose-risk models and mean radiation weighting factor for neutrons. Proton therapy confers lower predicted risk of second cancer than photon therapy for the pediatric medulloblastoma patient. PMID:23322160

  17. Long-term follow-up of proton irradiated malignant melanoma by glucose-fructose enhanced magnetic resonance imaging.

    PubMed

    Thuomas, K A; Naeser, P

    1997-02-01

    MR imaging is frequently used to diagnose uveal melanomas due to the characteristic short T2 relaxation time. T2 may be significantly prolonged within 2 h after ingestion of glucose and fructose due to changed water distribution in the melanoma. This method is used to follow melanomas for up to 6 years after proton beam irradiation. In the tumours, T2 was shortened in parallel in all the lesions during the first 9 months. After this, T2 increased only in tumours which showed recurrence. T2 determination and histopathological examination revealed no signs of recurrence in eyes which were enucleated due to neovascular glaucoma. It is concluded that MR imaging performed with carbohydrate loading, registers metabolic changes induced in the tumour, giving this method great validity in the follow-up of choroidal malignant melanoma after irradiation. Eighteen patients treated with proton beam for uveal melanoma at the cyclotron in Uppsala, Sweden, were followed.

  18. Effects of high energy x ray and proton irradiation on lead zirconate titanate thin films' dielectric and piezoelectric response

    SciTech Connect

    Bastani, Y.; Cortes-Pena, A. Y.; Wilson, A. D.; Gerardin, S.; Bagatin, M.; Paccagnella, A.; Bassiri-Gharb, N.

    2013-05-13

    The effects of irradiation by X rays and protons on the dielectric and piezoelectric response of highly (100)-textured polycrystalline Pb(Zr{sub x}Ti{sub 1-x})O{sub 3} (PZT) thin films have been studied. Low-field dielectric permittivity, remanent polarization, and piezoelectric d{sub 33,f} response all degraded with exposure to radiation, for doses higher than 300 krad. At first approximation, the degradation increased at higher radiation doses, and was stronger in samples exposed to X rays, compared to the proton-irradiated ones. Nonlinear and high-field dielectric characterization suggest a radiation-induced reduction of the extrinsic contributions to the response, attributed to increased pinning of the domain walls by the radiation-induced point defects.

  19. Uveal melanomas near the optic disc or fovea. Visual results after proton beam irradiation

    SciTech Connect

    Seddon, J.M.; Gragoudas, E.S.; Egan, K.M.; Glynn, R.J.; Munzenrider, J.E.; Austin-Seymour, M.; Goitein, M.; Verhey, L.; Urie, M.; Koehler, A.

    1987-04-01

    Proximity to the disc and fovea is a risk factor for visual loss after proton beam irradiation of uveal melanomas. Of 562 eyes treated over a 10-year period with pretreatment visual acuity of 20/200 or better, 363 (64.6%) contained tumors within 2 disc diameters (DD) of the disc or fovea. Rates of visual loss after treatment to worse than 20/200 and causes of visual decline were evaluated using Kaplan-Meier analysis. Cumulative rates of visual loss among subjects with tumors near the disc or fovea were 33 and 47% 1 and 2 years after treatment compared to 17 and 28%, respectively, for subjects with tumors located farther from both structures. The leading cause of visual loss in the first year among eyes with tumors near the disc or fovea was retinal detachment. Controlling for other predictors of visual loss to worse than 20/200, location near the disc or fovea was independently related to visual loss primarily due to retinal detachment, cataract, and radiation retinopathy. Despite the unfavorable location of these tumors, over half of patients with 20/200 or better pretreatment visual acuity had useful vision 2 years after treatment.

  20. Room temperature preparation of Pt-decorated MWCNTs by using proton beam irradiation

    NASA Astrophysics Data System (ADS)

    Kim, Yeong-Joon; Lee, Yoon Ji; Song, Jae Hee

    2016-09-01

    We present a facile one-pot preparation route for the production of multiwalled carbon nanotube (MWCNT)-Pt nanoparticle composites in an aqueous solution at room temperature by using proton beam irradiation process without the addition of any reducing reagents. We utilized hexade-cyltrimethylammonium bromide (CTAB)-stabilized pristine and thiol-functionalized MWCNTs for the synthesis of MWCNT-Pt nanoparticle composites and compared the deposition trends of the platinum nanoparticles onto the surfaces of pristine MWCNTs and surface-modified MWCNTs, respectively. Thiolated MWCNTs were densely and uniformly decorated with Pt nanoparticles while pristine MWCNTs were not. The Pt nanostructures on the surfaces of MWCNTs were spherical, and the average diameter was in the range of ~2 nm. Also, two different metal precursors, H2PtCl6 and Na2PtCl6, were used to find any distinguishable decoration patterns on the surface-modified MWCNTs; however, the deposition patterns were observed to be not very different.

  1. Study of radiation induced deep-level defects in proton irradiated AlGaAs-GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Li, S. S.

    1980-01-01

    Radiation induced deep-level defects (both electron and hole traps) in proton irradiated AlGaAs-GaAs p-n junction solar cells are investigated along with the correlation between the measured defect parameters and the solar cell performance parameters. The range of proton energies studied was from 50 KeV to 10 MeV and the proton fluence was varied from 10 to the 10th power to 10 to the 13th power P/sq cm. Experimental tools employed include deep-level transient spectroscopy, capacitance-voltage, current voltage, and SEM-EBIC methods. Defect and recombination parameters such as defect density and energy level, capture cross section, carrier lifetimes and effective hole diffusion lengths in n-GaAs LPE layers were determined from these measurements.

  2. Optically stimulated luminescence from Al 2O 3:C irradiated with 10-60 MeV protons

    NASA Astrophysics Data System (ADS)

    Edmund, J. M.; Andersen, C. E.; Greilich, S.; Sawakuchi, G. O.; Yukihara, E. G.; Jain, M.; Hajdas, W.; Mattsson, S.

    2007-09-01

    We investigated the potential use of Al 2O 3:C for medical proton dosimetry. Detector crystals coupled to fiber-optic cables were irradiated in proton beams with energies from 10 to 60 MeV. The key finding is that the initial intensity of the optically stimulated luminescence (OSL) signal is energy independent for small detectors (<0.5 mm) and relatively small doses (<0.3 Gy). This feature is related to the supralinearity of the detectors dose-response to low linear energy transfer (LET) radiation. The results show that our system can be used in medical proton dosimetry without LET-dependent correction factors in the dose and energy interval investigated.

  3. Measurement of prompt gamma profiles in inhomogeneous targets with a knife-edge slit camera during proton irradiation

    NASA Astrophysics Data System (ADS)

    Priegnitz, M.; Helmbrecht, S.; Janssens, G.; Perali, I.; Smeets, J.; Vander Stappen, F.; Sterpin, E.; Fiedler, F.

    2015-06-01

    Proton and ion beam therapies become increasingly relevant in radiation therapy. To fully exploit the potential of this irradiation technique and to achieve maximum target volume conformality, the verification of particle ranges is highly desirable. Many research activities focus on the measurement of the spatial distributions of prompt gamma rays emitted during irradiation. A passively collimating knife-edge slit camera is a promising option to perform such measurements. In former publications, the feasibility of accurate detection of proton range shifts in homogeneous targets could be shown with such a camera. We present slit camera measurements of prompt gamma depth profiles in inhomogeneous targets. From real treatment plans and their underlying CTs, representative beam paths are selected and assembled as one-dimensional inhomogeneous targets built from tissue equivalent materials. These phantoms have been irradiated with monoenergetic proton pencil beams. The accuracy of range deviation estimation as well as the detectability of range shifts is investigated in different scenarios. In most cases, range deviations can be detected within less than 2 mm. In close vicinity to low-density regions, range detection is challenging. In particular, a minimum beam penetration depth of 7 mm beyond a cavity is required for reliable detection of a cavity filling with the present setup. Dedicated data post-processing methods may be capable of overcoming this limitation.

  4. Synchrotron FTIR shows evidence of DNA damage and lipid accumulation in prostate adenocarcinoma PC-3 cells following proton irradiation

    NASA Astrophysics Data System (ADS)

    Lipiec, Ewelina; Bambery, Keith R.; Heraud, Phil; Hirschmugl, Carol; Lekki, Janusz; Kwiatek, Wojciech M.; Tobin, Mark J.; Vogel, Christian; Whelan, Donna; Wood, Bayden R.

    2014-09-01

    Synchrotron Radiation Fourier Transform Infrared (SR-FTIR) spectra of single human prostate adenocarcinoma PC-3 cells, irradiated with a defined number of 2 MeV protons generated by a proton microbeam along with non-irradiated control cells, were analysed using multivariate methods. A number of different Principal Component Analysis (PCA) models were tested and the spectral ranges associated with nucleic acids, proteins and lipids were analysed separately. The results show a dose dependent shift of the Osbnd Psbnd O asymmetric stretching mode from 1234 cm-1 to 1237 cm-1, consistent with local disorder in the B-DNA conformation along with a change in intensity of the Osbnd Psbnd O symmetric stretching band at 1083 cm-1 indicative of chromatin fragmentation - the natural consequence of a high number of DNA Double Strand Breaks (DSBs). 2D mapping of characteristic functional groups at the diffraction limit shows evidence of lipid deposition and chromatin condensation in cells exposed to protons indicative of cell apoptosis following irradiation. These studies lay the foundation for understanding the macromolecular changes that occur to cells in response to radiation therapy, which has important implications in the treatment of tumours.

  5. Measurement of prompt gamma profiles in inhomogeneous targets with a knife-edge slit camera during proton irradiation.

    PubMed

    Priegnitz, M; Helmbrecht, S; Janssens, G; Perali, I; Smeets, J; Vander Stappen, F; Sterpin, E; Fiedler, F

    2015-06-21

    Proton and ion beam therapies become increasingly relevant in radiation therapy. To fully exploit the potential of this irradiation technique and to achieve maximum target volume conformality, the verification of particle ranges is highly desirable. Many research activities focus on the measurement of the spatial distributions of prompt gamma rays emitted during irradiation. A passively collimating knife-edge slit camera is a promising option to perform such measurements. In former publications, the feasibility of accurate detection of proton range shifts in homogeneous targets could be shown with such a camera. We present slit camera measurements of prompt gamma depth profiles in inhomogeneous targets. From real treatment plans and their underlying CTs, representative beam paths are selected and assembled as one-dimensional inhomogeneous targets built from tissue equivalent materials. These phantoms have been irradiated with monoenergetic proton pencil beams. The accuracy of range deviation estimation as well as the detectability of range shifts is investigated in different scenarios. In most cases, range deviations can be detected within less than 2 mm. In close vicinity to low-density regions, range detection is challenging. In particular, a minimum beam penetration depth of 7 mm beyond a cavity is required for reliable detection of a cavity filling with the present setup. Dedicated data post-processing methods may be capable of overcoming this limitation.

  6. Dominant front-side acceleration of energetic proton beams from plastic targets irradiated by an ultraintense laser pulse

    SciTech Connect

    Lee, K.; Park, S. H.; Cha, Y.-H.; Lee, Y. W.; Jeong, Y. U.; Lee, J. Y.; Kim, K. N.

    2011-01-15

    An experimental observation has been made by using aluminum-coated Mylar foils, which strongly supports that in the case of plastic target, the energetic part of the proton beam originates from the front-side of the target. When a 30 fs laser pulse with an intensity of 1.6x10{sup 19} W/cm{sup 2} was irradiated on the 12.5-{mu}m-thick Mylar side of the aluminum-coated Mylar foil, the maximum proton energy was reduced by a factor 5.5 as compared to that of 3.3 MeV observed from the single layer of the Mylar foil. With the help of a two-dimensional particle-in-cell simulation, these observations can be interpreted that in the case of plastic target, the energetic proton beam originates from the front-side of the target. In the case of an aluminum-coated 6-{mu}m-thick Mylar foil, more energetic proton beams of 4.7 MeV were also observed when the laser pulse was irradiated on the aluminum side as compared to those of 3.4 MeV from the single Mylar foil.

  7. Experimental investigation of stress effect on swelling and microstructure of Fe-16Cr-15Ni-3Mo-Nb austenitic stainless steel under low-temperature irradiation up to high damage dose in the BOR-60 reactor

    NASA Astrophysics Data System (ADS)

    Neustroev, V. S.; Ostrovsky, Z. E.; Shamardin, V. K.

    2004-08-01

    The present paper was devoted to investigation of the stress effect on swelling and microstructure evolution of the Fe-15.8Cr-15.3Ni-2.8Mo-0.6Nb steel irradiated in the BOR-60 reactor at temperatures from 395 to 410 °C and damage doses from 79 to 98 dpa. Was found out that the stress increase leads to an increase of swelling, that can be associated with a decrease in incubation period with a practically constant swelling rate. Voids concentration increases at the first stage of irradiation when the void sizes are practically constant, and then the concentration reaches some saturation and swelling increase is caused by void growth.

  8. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    SciTech Connect

    Harlan U. Anderson; Wayne Huebner; Igor Kosacki

    2000-09-30

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. During this time period substantial progress has been made in developing low temperature deposition techniques to produce dense, nanocrystalline yttrium-stabilized zirconia films on both dense oxide and polymer substrates. Microstructural changes in unsupported nanocrystalline yttrium stabilized zirconia (ZrO{sub 2}:16%Y, or YSZ) thin films were examined as a function of temperature and annealing time in order to determine the grain growth exponent and the mechanisms of pinhole formation. Grain growth and pinhole formation were measured using high resolution transmission electron microscopy (HRTEM), normal imaging mode transmission electron microscopy (TEM), electron diffraction, and energy dispersive X-ray microanalysis (EDS). Grain growth was found to vary with a time exponent of about one half before pinhole formation and about one third after. Pinhole formation in 70 nm thick films occurred at temperatures near 600 C, corresponding to a grain size of about 15 nm, or a grain size to film thickness ration of approximately 0.25. The deposition of films on porous substrates is hampered by the penetration of the polymer precursor solution into the substrate whose pores as > 0.2 {micro}m, therefore much attention has to be paid to the development of porous colloidal oxide films onto surfaces. Thus during this line period we have been studying these films. Optical properties have proven to be an excellent way to study the quality of these nanoporous films. The influence of porosity and densification on optical properties of films on sapphire substrates that were prepared from water colloidal suspensions of small ({approx}5nm) particles of ceria was investigated. The colloidal ceria films have initially very porous structure (porosity about 50%) and densification starts at about 600 C accompanied by

  9. Investigations of ultrafast charge dynamics in laser-irradiated targets by a self probing technique employing laser driven protons

    NASA Astrophysics Data System (ADS)

    Ahmed, H.; Kar, S.; Cantono, G.; Nersisyan, G.; Brauckmann, S.; Doria, D.; Gwynne, D.; Macchi, A.; Naughton, K.; Willi, O.; Lewis, C. L. S.; Borghesi, M.

    2016-09-01

    The divergent and broadband proton beams produced by the target normal sheath acceleration mechanism provide the unique opportunity to probe, in a point-projection imaging scheme, the dynamics of the transient electric and magnetic fields produced during laser-plasma interactions. Commonly such experimental setup entails two intense laser beams, where the interaction produced by one beam is probed with the protons produced by the second. We present here experimental studies of the ultra-fast charge dynamics along a wire connected to laser irradiated target carried out by employing a 'self' proton probing arrangement - i.e. by connecting the wire to the target generating the probe protons. The experimental data shows that an electromagnetic pulse carrying a significant amount of charge is launched along the wire, which travels as a unified pulse of 10s of ps duration with a velocity close to speed of light. The experimental capabilities and the analysis procedure of this specific type of proton probing technique are discussed.

  10. Intermediate-to-low temperature protonic ceramic membrane fuel cells with Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3-δ-BaZr 0.1Ce 0.7Y 0.2O 3-δ composite cathode

    NASA Astrophysics Data System (ADS)

    Lin, Bin; Ding, Hanping; Dong, Yingchao; Wang, Songlin; Zhang, Xiaozhen; Fang, Daru; Meng, Guangyao

    The perovskite-type Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3-δ-BaZr 0.1Ce 0.7Y 0.2O 3-δ (BSCF-BZCY) composite oxides were synthesized by a modified Pechini method and examined as a novel composite cathode for intermediate-to-low temperature protonic ceramic membrane fuel cells (ILT-PCMFCs). Thin proton-conducting BaZr 0.1Ce 0.7Y 0.2O 3-δ (BZCY) electrolyte and NiO-BaZr 0.1Ce 0.7Y 0.2O 3-δ (NiO-BZCY) anode functional layer were prepared over porous anode substrates composed of NiO-BaZr 0.1Ce 0.7Y 0.2O 3-δ by a one-step dry-pressing/co-firing process. A laboratory-sized quad-layer cell of NiO-BZCY/NiO-BZCY(∼50 μm)/BZCY(∼20 μm)/BSCF-BZCY(∼50 μm) was operated from 550 to 700 °C with humidified hydrogen (∼3% H 2O) as fuel and the static air as oxidant. A high open-circuit potential of 1.009 V, a maximum power density of 418 mW cm -2, and a low polarization resistance of the electrodes of 0.10 Ω cm 2 was achieved at 700 °C. These investigations have indicated that proton-conducting BZCY electrolyte with BSCF perovskite cathode is a promising material system for the next generation solid oxide fuel cells (SOFCs).

  11. Proton Beam Craniospinal Irradiation Reduces Acute Toxicity for Adults With Medulloblastoma

    SciTech Connect

    Brown, Aaron P.; Barney, Christian L.; Grosshans, David R.; McAleer, Mary Frances; Groot, John F. de; Puduvalli, Vinay K.; Tucker, Susan L.; Crawford, Cody N.; Khan, Meena; Khatua, Soumen; Gilbert, Mark R.; Brown, Paul D.; Mahajan, Anita

    2013-06-01

    Purpose: Efficacy and acute toxicity of proton craniospinal irradiation (p-CSI) were compared with conventional photon CSI (x-CSI) for adults with medulloblastoma. Methods and Materials: Forty adult medulloblastoma patients treated with x-CSI (n=21) or p-CSI (n=19) at the University of Texas MD Anderson Cancer Center from 2003 to 2011 were retrospectively reviewed. Median CSI and total doses were 30.6 and 54 Gy, respectively. The median follow-up was 57 months (range 4-103) for x-CSI patients and 26 months (range 11-63) for p-CSI. Results: p-CSI patients lost less weight than x-CSI patients (1.2% vs 5.8%; P=.004), and less p-CSI patients had >5% weight loss compared with x-CSI (16% vs 64%; P=.004). p-CSI patients experienced less grade 2 nausea and vomiting compared with x-CSI (26% vs 71%; P=.004). Patients treated with x-CSI were more likely to have medical management of esophagitis than p-CSI patients (57% vs 5%, P<.001). p-CSI patients had a smaller reduction in peripheral white blood cells, hemoglobin, and platelets compared with x-CSI (white blood cells 46% vs 55%, P=.04; hemoglobin 88% vs 97%, P=.009; platelets 48% vs 65%, P=.05). Mean vertebral doses were significantly associated with reductions in blood counts. Conclusions: This report is the first analysis of clinical outcomes for adult medulloblastoma patients treated with p-CSI. Patients treated with p-CSI experienced less treatment-related morbidity including fewer acute gastrointestinal and hematologic toxicities.

  12. NSBRI Radiation Effects: Carcinogenesis in Sprague-Dawley Rats Irradiated with Iron Ions, Protons, or Photons

    NASA Technical Reports Server (NTRS)

    Dicello, J. F.; Cucinotta, F. A.; Gridley, D. S.; Howard, S. P.; Novak, G. R.; Ricart-Arbona, R.; Strandberg, J. D.; Vazquez, M. E.; Williams, J. R.; Zhang, Y.; Zhou, H.; Huso, D. L.

    1999-01-01

    Our ability to confidently develop appropriate countermeasures for radiations in space in terms of shielding and design of a spacecraft, the mission scenario, or chemoprevention is severely limited by the uncertainties in both the risk itself and the change in that risk with intervention. Despite the fact that the risk of carcinogenesis from exposures of personnel to radiations on long-term missions is considered one of the worst hazards in space, only a limited amount of in-vivo data exist for tumor induction from exposures to protons or energetic heavy ions (HZEs) at lower doses. The most extensive work remains the landmark study. for tumor development in the harderian gland of the mouse. The objective of this study is to characterize the level of risk for tumor induction in another relevant animal model. Subsequent experiments are designed to test the hypothesis that the level of risk can be reduced by pharmaceutical intervention in the promoting and progressing stages of the disease rather than in the initiating stage. The work presented here results from a cooperative effort on the part of investigators from two projects of the Radiation-Effects Team of the National Space Biomedical Research Institute (NSBRI). The collaborating projects are the Core Project which is investigating the risk of carcinogenesis in Sprague-Dawley rats and the Chemoprevention Project which is investigating the ability of Tamoxifen to reduce the number of malignant tumors in the irradiated animals. Research at the cellular and subcellular levels is being conducted in two other projects of the Radiation-Effects Team, Cytogenetics with J. R. Williams as Principal Investigator and Mutations from Repeated DNA Sequences. Results for these other projects also are being presented at this Workshop.

  13. Effects of proton irradiation on the performance of InP/GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, Irving; Swartz, C. K.; Brinker, David J.; Wilt, D. M.

    1991-01-01

    InP solar cells are known to be more radiation resistant than either GaAs or Si. In addition, AMO total area efficiencies approaching 19 percent were attained for InP. However, the present high substrate cost presents a barrier to the eventual widespread use of InP cells in space. In addition, if cell thinning becomes desirable, their relative fragility presents a problem. For these reasons, the NASA Lewis Research Center has initiated a program, aimed at producing thin InP cells, by heteroepitaxial deposition of InP on cheaper, more durable substrates. To date, a short term feasibility study as Spire has resulted in cells processed from InP heteroepitaxially deposited on Si substrates with an intervening thin GaAs layer (InP/GaAs/Si) and cells produced from InP deposited on GaAs (InP/GaAs). As a result of this short study efficiencies of over 7 and 9 percent were achieved for InP/GaAs/Si and InP/GaAs respectively. Although these efficiencies are low, they represent a modest and encouraging starting point for a more intensive program. Obviously, when considering economy and mechanical strength, cells processed on silicon substrates are preferred. However, although the InP/GaAs cells are not the final desirable products of this program, their properties serve to highlight several roadblocks to be overcome in producing cells with the more desirable cost and strength properties. Hence, in the present case, the properties of the InP/GaAs cells before and after irradiation by 10 MeV protons are examined. A similar study of InP/GaAs/Si cells will be reported on at a later date.

  14. Deuteration of pentacene in benzoic acid: Monitoring the reaction kinetics via low-temperature optical spectroscopy

    SciTech Connect

    Corval, A.; Casalegno, R.; Astilean, S.; Trommsdorff, H.P.

    1992-06-25

    In the deuteration of pentacene in benzoic acid, this reaction is monitored via low-temperature optical spectroscopy to observe the proton-deuterium rate of exchange between the solvent and solute molecules. Of the 14 pentacene protons, 6 have an exchange rate 2 orders of magnitude greater than the remaining 8. 20 refs., 3 figs.

  15. Temperature Effects on the Mechanical Properties of Candidate SNS Target Container Materials after Proton and Neutron Irradiation

    SciTech Connect

    Byun, T.S.

    2001-11-09

    This report presents the tensile properties of EC316LN austenitic stainless steel and 9Cr-2WVTa ferritic/martensitic steel after 800 MeV proton and spallation neutron irradiation to doses in the range 0.54 to 2.53 dpa. Irradiation temperatures were in the range 30 to 100 C. Tensile testing was performed at room temperature (20 C) and 164 C to study the effects of test temperature on the tensile properties. Test materials displayed significant radiation-induced hardening and loss of ductility due to irradiation. The EC316LN stainless steel maintained notable strain-hardening capability after irradiation, while the 9Cr-2WVTa ferritic/martensitic steel posted negative strain hardening. In the EC316LN stainless steel, increasing the test temperature from 20 C to 164 C decreased the strength by 13 to 18% and the ductility by 8 to 36%. The tensile data for the EC316LN stainless steel irradiated in spallation conditions were in line with the values in a database for 316 stainless steels for doses up to 1 dpa irradiated in fission reactors at temperatures below 200 C. However, extra strengthening induced by helium and hydrogen contents is evident in some specimens irradiated to above about 1 dpa. The effect of test temperature for the 9Cr-2WVTa ferritic/martensitic steel was less significant than for the EC316LN stainless steel. In addition, strain-hardening behaviors were analyzed for EC316LN and 316L stainless steels. The strain-hardening rate of the 316 stainless steels was largely dependent on test temperature. It was estimated that the 316 stainless steels would retain more than 1% true stains to necking at 164 C after irradiation to 5 dpa. A calculation using reduction of area (RA) measurements and stress-strain data predicted positive strain hardening during plastic instability.

  16. Changes in the structural and thermal properties of poly(vinylidene fluoride-chlorotrifluoroethylene) irradiated with 4 MeV protons

    NASA Astrophysics Data System (ADS)

    Singh, Arjun; Kishore, Prateek; Singh, Manjit; Srivastava, Alok

    2015-10-01

    The radiation effects on semicrystalline poly(vinylidene fluoride-chlorotrifluoroethylene) copolymer [poly(VDF-CTFE)] induced by proton beam irradiation were investigated. The poly(VDF-CTFE) films were exposed to 4 MeV protons at different fluence in the range of 2.7 × 1013 to 65.0 × 1013 protons/cm2. Changes in the chemical structural and thermal properties of pristine films as well as irradiated samples were studied using Fourier Transform Infrared (FTIR) and thermal analytical techniques, namely Thermogravimetric Analysis and Differential Scanning Calorimetry (DSC), respectively. FTIR spectroscopic data revealed two new bands at 1650 and 1747 cm-1 for irradiated samples whose intensities gradually increased with increasing ion fluence from 2.7 × 1013 to 27.0 × 1013 protons/cm2 due to the formation of carbon-carbon double bonds. The thermal stability was found to decrease after proton irradiation due to chain-scission. DSC data revealed that the proton irradiation was found to change in heat of fusion and crystallinity depending upon the applied dose.

  17. Low Temperature Thermometry Using Inexpensive Silicon Diodes.

    ERIC Educational Resources Information Center

    Waltham, N. R.; And Others

    1981-01-01

    Describes the use of silicon diodes for low temperature thermometry in the teaching laboratory. A simple and inexpensive circuit for display of the diode forward voltage under constant current conditions is described, and its application in the evaluation of low cost silicon diodes as low temperature thermometers is presented. (SK)

  18. Comparison of cell repair mechanisms by means of chromosomal aberration induced by proton and gamma irradiation - preliminary results

    NASA Astrophysics Data System (ADS)

    Kowalska, A.; Czerski, K.; Kaczmarski, M.; Lewocki, M.; Masojć, B.; Łukowiak, A.

    2015-03-01

    DNA damage of peripheral blood lymphocytes exposed to gamma and proton irradiation is studied by means of chromosome aberrations to validate the efficiency of the repair mechanisms of individual cells. A new method based on an observed deviation from the Poisson statistics of the chromosome aberration number is applied for estimation of a repair factor ( RF) defined as a ratio between originally damaged cells to the amount of finally observed aberrations. The repair factors are evaluated by studying the variance of individual damage factors in a collective of healthy persons at a given dose as well as by using the chi-square analysis for the dose-effect curves. The blood samples from fifteen donors have been irradiated by Co60 gamma rays and from nine persons by 150 MeV protons with different doses up to 2 Gy. A standard extraction of lymphocyte has been used whereby dicentrics, acentrics and rings have been scored under a microscope. The RF values determined for the proton radiation are slightly larger than for gamma rays, indicating that up to 70% DNA double strand breaks can be repaired.

  19. Performances of miniature microstrip detectors made on oxygen enriched p-type substrates after very high proton irradiation

    NASA Astrophysics Data System (ADS)

    Casse, G.; Allport, P. P.; Martí i Garcia, S.; Lozano, M.; Turner, P. R.

    2004-12-01

    Silicon microstrip detectors with n-type implant read-out strips on FZ p-type bulk (n-in-p) show superior charge collection properties, after heavy irradiation, to the more standard p-strips in n-type silicon (p-in-n). It is also well established that oxygen-enriched n-type silicon substrates show better performance, in terms of degradation of the full depletion voltage after charged hadron irradiation, than the standard FZ silicon used for high energy physics detectors. Silicon microstrip detectors combining both the advantages of oxygenation and of n-strip read-out (n-in-n) have achieved high radiation tolerance to charged hadrons. The manufacturing of n-in-n detectors though requires double-sided processing, resulting in more complicated and expensive devices than standard p-in-n. A cheaper single-sided option, that still combines these advantages, is to use n-in-p devices. P-type FZ wafers have been oxygen-enriched by high temperature diffusion from an oxide layer and succesfully used to process miniature (1×1 cm 2) microstrip detectors. These detectors have been irradiated with 24 GeV/c protons in the CERN/PS T7 irradiation area up to ˜7.5×10 15 cm -2. We report results with these irradiated detectors in terms of the charge collection efficiency as a function of the applied bias voltage.

  20. Spacecraft Charging in Low Temperature Environments

    NASA Technical Reports Server (NTRS)

    Parker, Linda N.

    2007-01-01

    Spacecraft charging in plasma and radiation environments is a temperature dependent phenomenon due to the reduction of electrical conductivity in dielectric materials at low temperatures. Charging time constants are proportional to l/conductivity may become very large (on the order of days to years) at low temperatures and accumulation of charge densities in insulators in charging environments traditionally considered benign at ambient temperatures may be sufficient to produce charge densities and electric fields of concern in insulators at low temperatures. Low temperature charging is of interest because a number of spacecraft-primarily infrared astronomy and microwave cosmology observatories-are currently being design, built, and or operated at very cold temperatures on the order of 40K to 100K. This paper reviews the temperature dependence of spacecraft charging processes and material parameters important to charging as a function of temperature with an emphasis on low temperatures regimes.

  1. Thermal conductivity profile determination in proton-irradiated ZrC by spatial and frequency scanning thermal wave methods

    SciTech Connect

    Jensen, C.; Chirtoc, M.; Horny, N.; Antoniow, J. S.; Pron, H.; Ban, H.

    2013-10-07

    Using complementary thermal wave methods, the irradiation damaged region of zirconium carbide (ZrC) is characterized by quantifiably profiling the thermophysical property degradation. The ZrC sample was irradiated by a 2.6 MeV proton beam at 600 °C to a dose of 1.75 displacements per atom. Spatial scanning techniques including scanning thermal microscopy (SThM), lock-in infrared thermography (lock-in IRT), and photothermal radiometry (PTR) were used to directly map the in-depth profile of thermal conductivity on a cross section of the ZrC sample. The advantages and limitations of each system are discussed and compared, finding consistent results from all techniques. SThM provides the best resolution finding a very uniform thermal conductivity envelope in the damaged region measuring ∼52 ± 2 μm deep. Frequency-based scanning PTR provides quantification of the thermal parameters of the sample using the SThM measured profile to provide validation of a heating model. Measured irradiated and virgin thermal conductivities are found to be 11.9 ± 0.5 W m{sup −1} K{sup −1} and 26.7 ±1 W m{sup −1} K{sup −1}, respectively. A thermal resistance evidenced in the frequency spectra of the PTR results was calculated to be (1.58 ± 0.1) × 10{sup −6} m{sup 2} K W{sup −1}. The measured thermal conductivity values compare well with the thermal conductivity extracted from the SThM calibrated signal and the spatially scanned PTR. Combined spatial and frequency scanning techniques are shown to provide a valuable, complementary combination for thermal property characterization of proton-irradiated ZrC. Such methodology could be useful for other studies of ion-irradiated materials.

  2. Low-temperature NMR studies on inosine wobble base pairs.

    PubMed

    Janke, Eline M Basílio; Riechert-Krause, Fanny; Weisz, Klaus

    2011-07-01

    Base pairs formed by the inosine nucleoside (I) play an important role in many physiological processes as well as in various DNA technologies. Relative stabilities and favored base pair geometries of free inosine wobble base pairs in aprotic solvents have been determined through (1)H NMR measurements at room temperature and at very low temperatures in a freonic solvent. As indicated by its significantly deshielded imino proton, the Watson-Crick-type I·C base pair forms a remarkably strong NHN hydrogen bond. For the thermodynamically less stable I·A wobble base pair, two configurations of similar population coexist at 133 K in the slow hydrogen bond exchange regime, namely a Watson-Crick(I)-Watson-Crick(A) geometry and a Watson-Crick(I)-Hoogsteen(A) geometry. I·U base pairs are stabilized by two rather weak hydrogen bonds and are significantly disfavored over inosine self-associates in a low-temperature Freon solution. PMID:21644523

  3. An effective route for size- and morphology-controlled synthesis of Pt nanomaterials in aqueous solutions via proton beam irradiation

    NASA Astrophysics Data System (ADS)

    Kim, Yeong-Joon; Lee, Yoon Ji; Song, Jae Hee

    2015-02-01

    We present a facile one-pot synthetic route for the production of Pt nanomaterials via a simple proton beam irradiation process at room temperature. Size- and shape-controlled Pt nanostructures were prepared in an aqueous phase-based solution without the addition of any harsh reductants. We observed that the sizes and the morphologies of the resulting Pt nanoparticles were easily varied by changing the proton beam current and duration time. We also observed that the addition of isopropyl alcohol to the reaction mixture played a vital role in the morphology-controlled synthesis of Pt nanomaterials. We found that the size of the prepared Pt nanoparticles increased as the beam irradiation time was increased under the same beam current. When the beam irradiation time was set the same, the average particle size decreased as the beam current was increased. We also observed that the average size of the Pt nanocrystals generally increased as the concentration of isopropyl alcohol was increased, and more importantly, a gradual morphology change of the Pt nanocrystals was observed.

  4. The affect of erbium hydride on the conversion efficience to accelerated protons from ultra-shsort pulse laser irradiated foils

    SciTech Connect

    Offermann, Dustin Theodore

    2008-01-01

    This thesis work explores, experimentally, the potential gains in the conversion efficiency from ultra-intense laser light to proton beams using erbium hydride coatings. For years, it has been known that contaminants at the rear surface of an ultra-intense laser irradiated thin foil will be accelerated to multi-MeV. Inertial Confinement Fusion fast ignition using proton beams as the igniter source requires of about 1016 protons with an average energy of about 3MeV. This is far more than the 1012 protons available in the contaminant layer. Target designs must include some form of a hydrogen rich coating that can be made thick enough to support the beam requirements of fast ignition. Work with computer simulations of thin foils suggest the atomic mass of the non-hydrogen atoms in the surface layer has a strong affect on the conversion efficiency to protons. For example, the 167amu erbium atoms will take less energy away from the proton beam than a coating using carbon with a mass of 12amu. A pure hydrogen coating would be ideal, but technologically is not feasible at this time. In the experiments performed for my thesis, ErH3 coatings on 5 μm gold foils are compared with typical contaminants which are approximately equivalent to CH1.7. It will be shown that there was a factor of 1.25 ± 0.19 improvement in the conversion efficiency for protons above 3MeV using erbium hydride using the Callisto laser. Callisto is a 10J per pulse, 800nm wavelength laser with a pulse duration of 200fs and can be focused to a peak intensity of about 5 x 1019W/cm2. The total number of protons from either target type was on the order of 1010. Furthermore, the same experiment was performed on the Titan laser, which has a 500fs pulse duration, 150J of energy and can be focused to about 3 x 1020 W/cm2. In this experiment 1012 protons were seen from both erbium hydride and

  5. The Accumulation and Annealing of Radiation-Induced Defects and the Effect of Hydrogen on the Physicomechanical Properties of the V-4Ti-4Cr and V-10Ti-5Cr Vanadium-Based Alloys under Low-Temperature (at 77 K) Neutron Irradiation

    NASA Astrophysics Data System (ADS)

    Arbuzov, V. L.; Goshchitskii, B. N.; Sagaradze, V. V.; Danilov, S. E.; Zuev, Yu. N.; Kar'kin, A. E.; Parkhomenko, V. D.; Kozlov, A. V.; Chernov, V. M.

    2016-03-01

    The processes of the accumulation and annealing of radiation-induced defects that occur under low-temperature (at 77 K) irradiation (with an energy E > 0.1 MeV) of V-4Ti-4Cr and V-10Ti-5Cr bcc alloys both nonmodified and modified with hydrogen isotopes in a concentration of 200 ppm, as well as the effect of these processes on the physicomechanical properties of these alloys, have been studied. It has been found that the saturation of these alloys with hydrogen leads to slight changes in their strength and ductility characteristics. The irradiation of the alloys at the temperature of 77 K results in a substantial increase in their yield stress and ultimate strength, as well as a decrease in their ductility. In the course of the postradiation annealing of the alloys at a temperature of 130 K, the stage related to the migration of interstitial atoms is observed. At temperatures of 290-320 K, the recovery stage occurs due to the formation of vacancy clusters. The stage that occurs at a temperature of 470 K can be attributed to the formation of impurity-vacancy clusters. Possible mechanisms of the radiation-induced strengthening of the alloys during irradiation and subsequent annealing have been discussed.

  6. Measurement and modelling of radionuclide production in thick spherical targets irradiated isotropically with 1600 MeV protons

    SciTech Connect

    Michel, R.; Lange, H.J.; Leya, I.; Luepke, M.; Herpers, U.; Meltzow, B.; Roesel, R.; Filges, D.; Cloth, P.; Dragovitsch, P.

    1994-12-31

    Two thick spherical targets made of gabbro and of steel with radii of 25 and 10 cm, respectively, were isotropically irradiated with 1.6 GeV protons at the Saturne accelerator at Laboratoire National Saturne/Saclay in order to simulate the interactions of galactic cosmic ray (GCR) protons with stony and iron meteoroids. The artificial meteoroids contained large numbers of individual small targets of up to 27 elements, in which the depth-dependent production of residual nuclides was measured by {gamma}-, accelerator and conventional mass spectrometry. Theoretical production depth profiles were derived by folding depth-dependent spectra of primary and secondary particles calculated by the HERMES code system with experimental and theoretical production rates shortcomings of the cross section data base can be distinguished and medium-energy neutron cross sections can be improved.

  7. Effects of proton irradiation on luminescence and carrier dynamics of self-assembled III-V quatum dots

    NASA Technical Reports Server (NTRS)

    Leon, R.; Marcinkevicius, S.; Siegert, J.; Magness, B.; Taylor, W.; Lobo, C.

    2002-01-01

    The effects of proton irradiation (1.5 MeV) on photoluminescence intensities and carrier dynamics were compared between III-V quantum dots and similar quantum well structures. A significant enhancement in radiation tolerance is seen with three-dimensional quantum confinement. Measurements were carried out in different quantum dot (QD) structures, varying in material (InGaAs/GaAs and InAlAs/AlGaAs), QD surface density (4x10^8 to 3x10'^10 cm^-2), and substrate orientation [(100) and (311) B]. Similar trends were observed for all QD samples. A slight increase in PL emission after low to intermediate proton doses, are also observed in InGaAs/GaAs (100) QD structures. The latter is explained in terms of more efficient carrier transfer from the wetting layer via radiation-induced defects.

  8. Proton Irradiation Alters Expression of FGF-2 In Human Lens Epithelial Cells

    NASA Technical Reports Server (NTRS)

    Blakely, E. A.; Bjornstad, K. A.; Chang, P. Y.; McNamara, M. P.; Chang, E.

    1999-01-01

    We are investigating a role for proton radiation-induced changes in FGF-2 gene expression as part of the mechanism(s) underlying lens cell injury. Radiation injury to the human lens is associated with the induction of cataract following exposure to protons.

  9. Low-Temperature Power Electronics Program

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Dickman, John E.; Hammoud, Ahmad; Gerber, Scott

    1997-01-01

    Many space and some terrestrial applications would benefit from the availability of low-temperature electronics. Exploration missions to the outer planets, Earth-orbiting and deep-space probes, and communications satellites are examples of space applications which operate in low-temperature environments. Space probes deployed near Pluto must operate in temperatures as low as -229 C. Figure 1 depicts the average temperature of a space probe warmed by the sun for various locations throughout the solar system. Terrestrial applications where components and systems must operate in low-temperature environments include cryogenic instrumentation, superconducting magnetic energy storage, magnetic levitation transportation system, and arctic exploration. The development of electrical power systems capable of extremely low-temperature operation represents a key element of some advanced space power systems. The Low-Temperature Power Electronics Program at NASA Lewis Research Center focuses on the design, fabrication, and characterization of low-temperature power systems and the development of supporting technologies for low-temperature operations such as dielectric and insulating materials, power components, optoelectronic components, and packaging and integration of devices, components, and systems.

  10. Low Dose Gamma Irradiation Potentiates Secondary Exposure to Gamma Rays or Protons in Thyroid Tissue Analogs

    SciTech Connect

    Green, Lora M

    2006-05-25

    We have utilized our unique bioreactor model to produce three-dimensional thyroid tissue analogs that we believe better represent the effects of radiation in vivo than two-dimensional cultures. Our thyroid model has been characterized at multiple levels, including: cell-cell exchanges (bystander), signal transduction, functional changes and modulation of gene expression. We have significant preliminary data on structural, functional, signal transduction and gene expression responses from acute exposures at high doses (50-1000 rads) of gamma, protons and iron (Green et al., 2001a; 2001b; 2002a; 2002b; 2005). More recently, we used our DOE funding (ending Feb 06) to characterize the pattern of radiation modulated gene expression in rat thyroid tissue analogs using low-dose/low-dose rate radiation, plus/minus acute challenge exposures. Findings from these studies show that the low-dose/low-dose rate “priming” exposures to radiation invoked changes in gene expression profiles that varied with dose and time. The thyrocytes transitioned to a “primed” state, so that when the tissue analogs were challenged with an acute exposure to radiation they had a muted response (or an increased resistance) to cytopathological changes relative to “un-primed” cells. We measured dramatic differences in the primed tissue analogs, showing that our original hypothesis was correct: that low dose gamma irradiation will potentiate the repair/adaptation response to a secondary exposure. Implications from these findings are that risk assessments based on classical in vitro tissue culture assays will overestimate risk, and that low dose rate priming results in a reduced response in gene expression to a secondary challenge exposure, which implies that a priming dose provides enhanced protection to thyroid cells grown as tissue analogs. If we can determine that the effects of radiation on our tissue analogs more closely resemble the effects of radiation in vivo, then we can better

  11. Io's surface composition based on reflectance spectra of sulfur/salt mixtures and proton-irradiation experiments

    NASA Technical Reports Server (NTRS)

    Nash, D. B.; Fanale, F. P.

    1977-01-01

    Available full-disk reflectance spectra of Io in the range 0.3 to 2.5 microns have been used to determine a surface compositional model for Io that is consistent with Io's other known chemical and physical properties. Results indicate that the surface of Io contains abundant dehydrated salts of high Na, Mg, and Fe(3+) content such as bloedite and ferrous iron sulfate. Experiments were performed studying the irradiation damage effects from low-energy proton bombardment, since Io is immersed in Jupiter's magnetosphere.

  12. [Low temperature plasma technology for biomass refinery].

    PubMed

    Fu, Xiaoguo; Chen, Hongzhang

    2014-05-01

    Biorefinery that utilizes renewable biomass for production of fuels, chemicals and bio-materials has become more and more important in chemical industry. Recently, steam explosion technology, acid and alkali treatment are the main biorefinery treatment technologies. Meanwhile, low temperature plasma technology has attracted extensive attention in biomass refining process due to its unique chemical activity and high energy. We systemically summarize the research progress of low temperature plasma technology for pretreatment, sugar platflow, selective modification, liquefaction and gasification in biomass refinery. Moreover, the mechanism of low temperature plasma in biorefinery and its further development were also discussed.

  13. Improved Low Temperature Performance of Supercapacitors

    NASA Technical Reports Server (NTRS)

    Brandon, Erik J.; West, William C.; Smart, Marshall C.; Gnanaraj, Joe

    2013-01-01

    Low temperature double-layer capacitor operation enabled by: - Base acetonitrile / TEATFB salt formulation - Addition of low melting point formates, esters and cyclic ethers center dot Key electrolyte design factors: - Volume of co-solvent - Concentration of salt center dot Capacity increased through higher capacity electrodes: - Zeolite templated carbons - Asymmetric cell designs center dot Continuing efforts - Improve asymmetric cell performance at low temperature - Cycle life testing Motivation center dot Benchmark performance of commercial cells center dot Approaches for designing low temperature systems - Symmetric cells (activated carbon electrodes) - Symmetric cells (zeolite templated carbon electrodes) - Asymmetric cells (lithium titanate/activated carbon electrodes) center dot Experimental results center dot Summary

  14. Conductivity compensation in p-6H-SiC in irradiation with 8-MeV protons

    SciTech Connect

    Lebedev, A. A.; Kozlovski, V. V.; Belov, S. V.; Bogdanova, E. V.; Oganesyan, G. A.

    2011-09-15

    Carrier removal rate (V{sub d}) in p-6H-SiC in its irradiation with 8-MeV protons has been studied. The p-6H-SiC samples were produced by sublimation in vacuum. V{sub d} was determined by analysis of capacitance-voltage characteristics and from results of Hall effect measurements. It was found that complete compensation of samples with initial value of N{sub a} - N{sub d} Almost-Equal-To 1.5 Multiplication-Sign 10{sup 18} cm{sup -3} occurs at an irradiation dose of {approx}1.1 Multiplication-Sign 10{sup 16} cm{sup -2}. In this case, the carrier removal rate was {approx}130 cm{sup -1}.

  15. Investigation of the radiation resistance of triple-junction a-Si:H alloy solar cells irradiated with 1.00 MeV protons

    NASA Technical Reports Server (NTRS)

    Lord, Kenneth R., II; Walters, Michael R.; Woodyard, James R.

    1993-01-01

    The effect of 1.00 MeV proton irradiation on hydrogenated amorphous silicon alloy triple-junction solar cells is reported for the first time. The cells were designed for radiation resistance studies and included 0.35 cm(sup 2) active areas on 1.0 by 2.0 cm(sup 2) glass superstrates. Three cells were irradiated through the bottom contact at each of six fluences between 5.10E12 and 1.46E15 cm(sup -2). The effect of the irradiations was determined with light current-voltage measurements. Proton irradiation degraded the cell power densities from 8.0 to 98 percent for the fluences investigated. Annealing irradiated cells at 200 C for two hours restored the power densities to better than 90 percent. The cells exhibited radiation resistances which are superior to cells reported in the literature for fluences less than 1E14 cm(sup -2).

  16. Microwave-induced resistance oscillations at low temperatures

    NASA Astrophysics Data System (ADS)

    Martin, Peter; Zudov, Michael; Watson, John; Manfra, Michael; Reno, John; Pfeiffer, Loren; West, Kenneth

    2013-03-01

    At low temperatures, the amplitude of microwave-induced resistance oscillations in two dimensional electron systems is predicted to scale as 1 /T2 . In contrast to this prediction, our experiments shows that the amplitude tends to saturate at low temperatures, even in the regime of very low microwave intensities. In this talk we will discuss radiation-induced heating as a possible source of the observed saturation and ways to estimate actual temperature of irradiated 2D electrons. The work at Minnesota and Purdue was supported by the NSF Grant No. DMR-0548014 and DOE Grant No. DE-SC0006671, respectively. The work at Princeton was partially funded by the Gordon and Betty Moore Foundation and the NSF MRSEC Program.

  17. Solution-phase synthesis of nanomaterials at low temperature

    NASA Astrophysics Data System (ADS)

    Zhu, Yongchun; Qian, Yitai

    2009-01-01

    This paper reviews the solution-phase synthesis of nanoparticles via some routes at low temperatures, such as room temperature route, wave-assisted synthesis (γ-irradiation route and sonochemical route), directly heating at low temperatures, and hydrothermal/solvothermal methods. A number of strategies were developed to control the shape, the size, as well as the dispersion of nanostructures. Using diethylamine or n-butylamine as solvent, semiconductor nanorods were yielded. By the hydrothermal treatment of amorphous colloids, Bi2S3 nanorods and Se nanowires were obtained. CdS nanowires were prepared in the presence of polyacrylamide. ZnS nanowires were obtained using liquid crystal. The polymer poly (vinyl acetate) tubule acted as both nanoreactor and template for the CdSe nanowire growth. Assisted by the surfactant of sodium dodecyl benzenesulfonate (SDBS), nickel nanobelts were synthesized. In addition, Ag nanowires, Te nanotubes and ZnO nanorod arrays could be prepared without adding any additives or templates.

  18. Performance, Defect Behavior and Carrier Enhancement in Low Energy, Proton Irradiated p(+)nn(+) InP Solar Cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Rybicki, G. C.; Vargas-Aburto, C.; Jain, R. K.; Scheiman, D.

    1994-01-01

    InP p(+)nn(+) cells, processed by MOCVD, were irradiated by 0.2 MeV protons and their performance and defect behavior observed to a maximum fluence of 10(exp 13)/sq cm. Their radiation induced degradation, over this fluence range, was considerably+less than observed for similarly irradiated, diffused junction n p InP cells. Significant degradation occurred in both the cell's emitter and base regions the least degradation occurring in the depletion region. A significant increase in series resistance occurs at the highest fluenc.e. Two majority carrier defect levels, E7 and E10, are observed by DLTS with activation energies at (E(sub C) - 0.39)eV and (E(sub C) - 0.74)eV respectively. The relative concentration of these defects differs considerably from that observed after 1 MeV electron irradiation. An increased carrier concentration in the cell's n-region was observed at the highest proton fluence, the change in carrier concentration being insignificant at the lower fluences. In agreement with previous results, for 1 and 1.5 MeV electron irradiated InP p(+)n junctions, the defect level E10 is attributed to a complex between zinc, diffused into the n-region from the zinc doped emitter, and a radiation induced defect. The latter is assumed to be either a phosphorus vacancy or interstitial. The increased, or enhanced carrier concentration is attributed to this complex acting as a donor.

  19. Thermal stability of deep level defects induced by high energy proton irradiation in n-type GaN

    SciTech Connect

    Zhang, Z.; Farzana, E.; Sun, W. Y.; Arehart, A. R.; Ringel, S. A.; Chen, J.; Zhang, E. X.; Fleetwood, D. M.; Schrimpf, R. D.; McSkimming, B.; Kyle, E. C. H.; Speck, J. S.

    2015-10-21

    The impact of annealing of proton irradiation-induced defects in n-type GaN devices has been systematically investigated using deep level transient and optical spectroscopies. Moderate temperature annealing (>200–250 °C) causes significant reduction in the concentration of nearly all irradiation-induced traps. While the decreased concentration of previously identified N and Ga vacancy related levels at E{sub C} − 0.13 eV, 0.16 eV, and 2.50 eV generally followed a first-order reaction model with activation energies matching theoretical values for N{sub I} and V{sub Ga} diffusion, irradiation-induced traps at E{sub C} − 0.72 eV, 1.25 eV, and 3.28 eV all decrease in concentration in a gradual manner, suggesting a more complex reduction mechanism. Slight increases in concentration are observed for the N-vacancy related levels at E{sub C} − 0.20 eV and 0.25 eV, which may be due to the reconfiguration of other N-vacancy related defects. Finally, the observed reduction in concentrations of the states at E{sub C} − 1.25 and E{sub C} − 3.28 eV as a function of annealing temperature closely tracks the detailed recovery behavior of the background carrier concentration as a function of annealing temperature. As a result, it is suggested that these two levels are likely to be responsible for the underlying carrier compensation effect that causes the observation of carrier removal in proton-irradiated n-GaN.

  20. Proton beam irradiation induced synthesis of Size- and morphology-controlled Pt nanomaterials in an aqueous solution

    NASA Astrophysics Data System (ADS)

    Kim, Yeong-Joon; Lee, Yoon Ji; Song, Jae Hee

    2015-10-01

    We present a facile one-pot preparation route for the production of Pt nanomaterials by using a simple proton beam irradiation process at room temperature. Size- and shape-controlled Pt nanoparticles were prepared in an aqueous solution without the addition of any harsh reducing agents. The morphology of the Pt nanoparticles was easily tuned by varying the average beam current and duration time. The addition of isopropyl alcohol to the reaction mixture was observed to have played a vital role in the synthesis of Pt cubes. We found that the shape of the prepared Pt nanoparticles without the addition of isopropyl alcohol was ~99% spheres while Pt nanoparticles synthesized with the addition of isopropyl alcohol under the same reaction conditions was over 70% cubes. The beam irradiation time was also an important factor for optimizing the morphologycontrolled preparation condition for Pt cubes. As the beam irradiation time was increased from 20 min to 120 min, the percentage of cubes increased from 7% to 70%; however, for extended irradiation time, the percentage of cubes fell off.

  1. Proton-induced coloring of multicomponent glasses. [absorption saturation due to irradiation in space environment simulation

    NASA Technical Reports Server (NTRS)

    Bartusiak, M. F.; Becher, J.

    1979-01-01

    The paper describes the coloring induced by 85-MeV protons in three Schott glasses representative of glass types used as focusing elements in the International Ultraviolet Explorer Fine Error Sensor. It is shown that the absorption (i.e., coloring) induced in each glass by the radiation can be resolved into three optical absorption bands in the near UV-visible range. It is also discussed how that absorption grows with increasing dosages of protons, thus providing the means to predict degradation in any of the three glasses for a particular fluence of proton radiation.

  2. Degradation of poly(methylmethacrylate) by deep ultraviolet, x-ray, electron beam, and proton beam irradiations

    SciTech Connect

    Choi, J.O.; Moore, J.A.; Corelli, J.C.; Silverman, J.P.; Bakhru, H.

    1988-11-01

    The chemical changes in poly(methylmethacrylate) (PMMA) caused by irradiation with deep ultraviolet (UV), x-ray, electron, and proton beams were studied by gel permeation chromatography, Fourier-transform infrared, and UV spectroscopy. The quantitative analysis of spectroscopic changes (Beer's law) demonstrated a 1:1 correspondence between the disappearance of ester groups and the generation of double bonds in the polymer chain by all types of radiation. The ratio of main chain scission to changes in the number of ester groups and unsaturated bonds was compared to determine the characteristics of degradation of PMMA by the different types of radiation. This ratio for deep UV data was very close to the quantum yield of main chain scission of PMMA as reported in the literature. High-energy radiation was /similar to/0 x more efficient than deep UV in causing main chain scission with removal of fewer ester groups. Protons induced more main chain scission than electrons. X-ray irradiation was the most efficient at causing main chain scission of the four different types of radiation.

  3. Supine Craniospinal Irradiation Using a Proton Pencil Beam Scanning Technique Without Match Line Changes for Field Junctions

    SciTech Connect

    Lin, Haibo Ding, Xuanfeng; Kirk, Maura; Liu, Haoyang; Zhai, Huifang; Hill-Kayser, Christine E.; Lustig, Robert A.; Tochner, Zelig; Both, Stefan; McDonough, James

    2014-09-01

    Purpose: To propose and validate a craniospinal irradiation approach using a proton pencil beam scanning technique that overcomes the complexity of the planning associated with feathering match lines. Methods and Materials: Ten craniospinal irradiation patients had treatment planned with gradient dose optimization using the proton pencil beam scanning technique. The robustness of the plans was evaluated by shifting the isocenter of each treatment field by ±3 mm in the longitudinal direction and was compared with the original nonshifted plan with metrics of conformity number, homogeneity index, and maximal cord doses. An anthropomorphic phantom study using film measurements was carried out on a plan with 5-cm junction length. To mimic setup errors in the phantom study, fields were recalculated with isocenter shifts of 1, 3, 5, and 10 mm longitudinally, and compared with the original plans and measurements. Results: Uniform dose coverage to the entire target volumes was achieved using the gradient optimization approach with averaged junction lengths of 6.7 ± 0.5 cm. The average conformity number and homogeneity index equaled 0.78 ± 0.03 and 1.09 ± 0.01, respectively. Setup errors of 3 mm per field (6 mm in worst-case scenario) caused on average 4.6% lower conformity number 2.5% higher homogeneity index and maximal cord dose of 4216.1 ± 98.2 cGy. When the junction length was 5 cm or longer, setup errors of 6 mm resulted in up to 12% dosimetric deviation. Consistent results were reached between film measurements and planned dose profiles in the junction area. Conclusions: Longitudinal setup errors directly reduce the dosimetric accuracy of the proton craniospinal irradiation treatment with matched proton pencil beam scanning fields. The reported technique creates a slow dose gradient in the junction area, which makes the treatment more robust to longitudinal setup errors compared to conventional feathering methods.

  4. Estimating the effectiveness of human-cell irradiation by protons of a therapeutic beam of the joint institute for nuclear research phasotron using cytogenetic methods

    NASA Astrophysics Data System (ADS)

    Zaytseva, E. M.; Govorun, R. D.; Mitsin, G. V.; Molokanov, A. G.

    2011-11-01

    The effectiveness of the impact of therapeutic proton beams in human cells with respect to the criterion of formation of chromosome aberrations in human-blood lymphocytes is estimated. The physical characteristics of radiation (proton LET at the input of the object and in the region of the modified Bragg peak) and the role of the biological factor (the differences in the radiosensitivity of nondividing cells corresponding to the irradiation of normal tissues along the proton-beam path and tumor tissues) are taken into account. The relative biological effectiveness of protons is ˜1 at the beam input of the object and ˜1.2 in the Bragg peak region. Taking into account the higher radiosensitivity of dividing cells in the G 2 phase of the cell cycle, the irradiation effectiveness increases to ˜1.4.

  5. Proton emission from thin hydrogenated targets irradiated by laser pulses at 10{sup 16} W/cm{sup 2}

    SciTech Connect

    Torrisi, L.; Giuffrida, L.; Cirrone, P.; Cutroneo, M.; Picciotto, A.; Krasa, J.; Margarone, D.; Velyhan, A.; Laska, L.; Ullschmied, J.; Wolowski, J.; Badziak, J.; Rosinski, M.

    2012-02-15

    The iodine laser at PALS Laboratory in Prague, operating at 1315 nm fundamental harmonics and at 300 ps FWHM pulse length, is employed to irradiate thin hydrogenated targets placed in vacuum at intensities on the order of 10{sup 16} W/cm{sup 2}. The laser-generated plasma is investigated in terms of proton and ion emission in the forward and backward directions. The time-of-flight technique, using ion collectors and semiconductor detectors, is used to measure the ion currents and the corresponding velocities and energies. Thomson parabola spectrometer is employed to separate the contribution of the ion emission from single laser shots. A particular attention is given to the proton production in terms of the maximum energy, emission yield, and angular distribution as a function of the laser energy, focal position, target thickness, and composition. Metallic and polymeric targets allow to generate protons with large energy range and different yield, depending on the laser, target composition, and target geometry properties.

  6. Low-temperature volumetric receiver concept

    NASA Astrophysics Data System (ADS)

    Drost, M. K.

    1988-09-01

    This document describes an alternative solar central receiver concept that offers the potential for a substantial reduction in the cost of electrical energy. The concept consists of a low temperature volumetric receiver which supplies 1100 F air to a Kalina cycle heat engine. Hot air can also be supplied to a packed bed of Dresser basalt where the hot air is used to heat the bed. The thermal energy stored in the bed can be extracted and supplied to the Kalina cycle during periods of low insolation. Previous investigations of the volumetric receiver concentrated on high temperature applications. The results showed that the volumetric concept could be very efficient, but the receiver was expensive and there were significant technical problems. Areas of technical uncertainty included fiber durability, the feasibility of inducing a preswirl and cost effective applications. The use of the volumetric receiver to produce low temperature will avoid the problems identified in the high temperature studies. The attractiveness of the low temperature concept is enhanced by the availability of the Kalina cycle. This heat engine was developed as a bottoming cycle for Brayton and Rankine cycle power plants. The key feature of the Kalina cycle is its ability to efficiently utilize the energy in a relatively low temperature heat source. The combination of the low temperature volumetric receiver and the Kalina cycle is particularly interesting.

  7. Low-temperature volumetric receiver concept

    SciTech Connect

    Drost, M.K.

    1988-09-01

    This document describes an alternative solar central receiver concept that offers the potential for a substantial reduction in the cost of electrical energy. The concept consists of a low temperature volumetric receiver which supplies 1100/degree/F air to a Kalina cycle heat engine. Hot air can also be supplied to a packed bed of Dresser basalt where the hot air is used to heat the bed. The thermal energy stored in the bed can be extracted and supplied to the Kalina cycle during periods of low insolation. Previous investigations of the volumetric receiver concentrated on high temperature applications. The results showed that the volumetric concept could be very efficient, but the receiver was expensive and there were significant technical problems. Areas of technical uncertainty included fiber durability, the feasibility of inducing a preswirl and cost effective applications. The use of the volumetric receiver to produce low temperature will avoid the problems identified in the high temperature studies. The attractiveness of the low temperature concept is enhanced by the availability of the Kalina cycle. This heat engine was developed as a bottoming cycle for Brayton and Rankine cycle power plants. The key feature of the Kalina cycle is its ability to efficiently utilize the energy in a relatively low temperature heat source. The combination of the low temperature volumetric receiver and the Kalina cycle is particularly interesting. 7 refs., 2 figs., 3 tabs.

  8. PIN photodiodes irradiated with 40- and 85-MeV protons

    NASA Technical Reports Server (NTRS)

    Reft, C. S.; Becher, J.; Kernell, R. L.

    1985-01-01

    PIN photodiodes were bombarded with 40- and 85-MeV protons to a fluence of 1.5 x 10 to the 11th p/sq cm, and the resulting change in spectral response in the near infrared was determined. The photocurrent, dark current, and pulse amplitude were measured as a function of proton fluence. Changes in these three measured properties are discussed in terms of changes in the diode's spectral response, minority carrier diffusion length, and depletion width. A simple model of induced radiation effects is presented which is in good agreement with the experimental results. The model assumes that incident protons produce charged defects within the depletion region simulating donor type impurities.

  9. Service life of metals at low temperatures

    NASA Technical Reports Server (NTRS)

    Verkin, B. I.; Lyubarskiy, I. M.; Grinberg, N. M.; Yakovenko, L. F.

    1974-01-01

    Current concepts of the nature of fatigue failure at low temperatures are presented on the basis of experimental results of various investigators. The fundamental approach to the technique for studying low-temperature fatigue is examined. The necessity for using the same medium at different fatigue test temperatures and also the necessity for taking into account the magnitude of the plastic deformation amplitude are confirmed. Experimental data from a study of the influence of low temperatures (down to liquid nitrogen temperatures) on the fatigue life of copper and armco-iron in dry air, over a wide range of deformations, are presented. These results are compared with microscopic and electron microscopic pictures of the surface of the deformed specimens.

  10. Photochemistry of cyclopentadiene isolated in low-temperature argon matrices

    NASA Astrophysics Data System (ADS)

    Miyazaki, Jun; Yamada, Yasuhiro

    2004-04-01

    The photochemistry of cyclopentadiene isolated in low-temperature argon matrices was studied by means of IR and UV/VIS spectroscopy. Bicyclo[2.1.0]pent-2-ene was formed by the irradiation of matrix-isolated cyclopentadiene using a super-high-pressure mercury lamp. When the matrix-isolated cyclopentadiene was irradiated with shorter wavelength using a low-pressure mercury lamp, further reactions of bicyclo[2.1.0]pent-2-ene were found to produce allylacetylene and vinylallene. While the photochemistry of cyclopentadiene to form bicyclo[2.1.0]pent-2-ene is known in a solution system, the production of allylacetylene and vinylallene in a matrix-isolated system has never been previously reported. The assignments of the species and the determination of the reaction mechanisms were performed using molecular orbital calculations.

  11. Low temperature monitoring system for subsurface barriers

    SciTech Connect

    Vinegar, Harold J.; McKinzie, II. Billy John

    2009-08-18

    A system for monitoring temperature of a subsurface low temperature zone is described. The system includes a plurality of freeze wells configured to form the low temperature zone, one or more lasers, and a fiber optic cable coupled to at least one laser. A portion of the fiber optic cable is positioned in at least one freeze well. At least one laser is configured to transmit light pulses into a first end of the fiber optic cable. An analyzer is coupled to the fiber optic cable. The analyzer is configured to receive return signals from the light pulses.

  12. Aluminium Sheet Metal Forming at Low Temperatures

    NASA Astrophysics Data System (ADS)

    Schneider, R.; Heine, B.; Grant, R. J.; Zouaoui, Z.

    2015-02-01

    Low-temperature forming technology offers a new potential for forming operations of aluminium wrought alloys which show a limited formability at ambient temperatures. This paper indicates the mechanical behaviour of the commercial aluminium alloys EN AW-5182 and EN AW-6016 at low temperatures. Stress-strain relationships at different temperatures were investigated through tensile testing experiments. Flow curves were extrapolated using an adapted mathematical constitutive relationship of flow stress and strain. A device which allows cupping tests at sub-zero temperatures was specially designed and a limiting dome height was determined.

  13. Photocarrier radiometry for predicting the degradation of electrical parameters of monocrystalline silicon (c-Si) solar cell irradiated by 100 KeV proton beams

    NASA Astrophysics Data System (ADS)

    Song, P.; Liu, J. Y.; Yuan, H. M.; Oliullah, Md.; Wang, F.; Wang, Y.

    2016-09-01

    In this study, the monocrystalline silicon (c-Si) solar cell irradiated by 100 KeV proton beams at various fluences is investigated. A one-dimensional two-layer carrier density wave model has been developed to estimate the minority carrier lifetime of n-region and p-region of the non-irradiated c-Si solar cell by best fitting with the experimental photocarrier radiometry (PCR) signal (the amplitude and the phase). Furthermore, the lifetime is used to determine the initial defect density of the quasi-neutral region (QNR) of the solar cell to predict its I-V characteristics. The theoretically predicted short-circuit current density (Jsc), and open-circuit voltage (Voc) of the non-irradiated samples are in good agreement with experiment. Then a three-region defect distribution model for the c-Si solar cell irradiated by proton beams is carried out to describe the defect density distribution according to Monte Carlo simulation results and the initial defect density of the non-irradiated sample. Finally, we find that the electrical measurements of Jsc and Voc of the solar cells irradiated at different fluences using 100 KeV proton beams are consistent with the PCR predicting results.

  14. SU-E-J-121: Measuring Prompt Gamma Emission Profiles with a Multi-Stage Compton Camera During Proton Beam Irradiation: Initial Studies

    SciTech Connect

    Polf, J; McCleskey, M; Brown, S; Mann, J; He, Z; Mackin, D; Beddar, S; Zheng, Y

    2014-06-01

    Purpose: Recent studies have suggested that the characteristics of prompt gammas (PG) emitted during proton beam irradiation are advantageous for determining beam range during treatment delivery. The purpose of this work was to determine the feasibility of determining the proton beam range from PG data measured with a prototype Compton camera (CC) during proton beam irradiation. Methods: Using a prototype multi-stage CC the PG emission from a water phantom was measured during irradiation with clinical proton therapy beams. The measured PG emission data was used to reconstruct an image of the PG emission using a backprojection reconstruction algorithm. One dimensional (1D) profiles extracted from the PG images were compared to: 1) PG emission data measured at fixed depths using collimated high purity Germanium and Lanthanum Bromide detectors, and 2) the measured depth dose profiles of the proton beams. Results: Comparisons showed that the PG emission profiles reconstructed from CC measurements agreed very well with the measurements of PG emission as a function of depth made with the collimated detectors. The distal falloff of the measured PG profile was between 1 mm to 4 mm proximal to the distal edge of the Bragg peak for proton beam ranges from 4 cm to 16 cm in water. Doses of at least 5 Gy were needed for the CC to measure sufficient data to image the PG profile and localize the distal PG falloff. Conclusion: Initial tests of a prototype CC for imaging PG emission during proton beam irradiation indicated that measurement and reconstruction of the PG profile was possible. However, due to limitations of the operational parameters (energy range and count rate) of the current CC prototype, doses of greater than a typical treatment dose (∼2 Gy) were needed to measure adequate PG signal to reconstruct viable images. Funding support for this project provided by a grant from DoD.

  15. Low temperature synthesis of methyl formate

    DOEpatents

    Mahajan, Devinder; Slegeir, William A.; Sapienza, Richard S.; O'Hare, Thomas E.

    1986-01-01

    A gas reaction process for the preferential production of methyl formate over the co-production of methanol wherein the reactant ratio of CO/H.sub.2 is upgraded and this reaction takes place at low temperatures of 50.degree.-150.degree. C. and moderate pressures of .gtoreq.100 psi.

  16. Industrial Applications of Low Temperature Plasmas

    SciTech Connect

    Bardsley, J N

    2001-03-15

    The use of low temperature plasmas in industry is illustrated by the discussion of four applications, to lighting, displays, semiconductor manufacturing and pollution control. The type of plasma required for each application is described and typical materials are identified. The need to understand radical formation, ionization and metastable excitation within the discharge and the importance of surface reactions are stressed.

  17. Fuzzy Logic Controller for Low Temperature Application

    NASA Technical Reports Server (NTRS)

    Hahn, Inseob; Gonzalez, A.; Barmatz, M.

    1996-01-01

    The most common temperature controller used in low temperature experiments is the proportional-integral-derivative (PID) controller due to its simplicity and robustness. However, the performance of temperature regulation using the PID controller depends on initial parameter setup, which often requires operator's expert knowledge on the system. In this paper, we present a computer-assisted temperature controller based on the well known.

  18. Structural changes in InP/Si solar cells following irradiation with protons to very high fluences

    NASA Astrophysics Data System (ADS)

    Messenger, S. R.; Jackson, E. M.; Burke, E. A.; Walters, R. J.; Xapsos, M. A.; Summers, G. P.

    1999-08-01

    Precisely how the short circuit current (JSC) is produced in a proton irradiated n+p InP/Si solar cell at very high fluence levels has been determined from combined measurements of the cell structure using electrochemical capacitance-voltage profiling and detailed analysis of the spectral quantum efficiency. Type conversion in the base region of the cell is shown to occur before an anomalous peak in the degradation curve for JSC is reached at high damage levels. The short circuit current, and hence the cell efficiency, ultimately collapse because the high absorption coefficient of InP eventually prevents the generation of electron-hole pairs close enough to the effective cell junction from being collected.

  19. Fabrication of low-loss silicon-on-oxidized-porous-silicon strip waveguide using focused proton-beam irradiation.

    PubMed

    Teo, E J; Bettiol, A A; Yang, P; Breese, M B H; Xiong, B Q; Mashanovich, G Z; Headley, W R; Reed, G T

    2009-03-01

    We have successfully fabricated low-loss silicon-on-oxidized-porous-silicon (SOPS) strip waveguides with high-index contrast using focused proton-beam irradiation and electrochemical etching. Smooth surface quality with rms roughness of 3.1 nm is achieved for a fluence of 1x10(15)/cm(2) after postoxidation treatment. Optical characterization at a wavelength of 1550 nm shows a loss of 1.1+/-0.4 dB/cm and 1.2+/-0.4 dB/cm in TE and TM polarization respectively, which we believe is the lowest reported loss for SOPS waveguides. This opens up new opportunities for all-silicon-based optoelectronics applications.

  20. Performance and temperature dependencies of proton irradiated n/p GaAs and n/p silicon cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.

    1985-01-01

    The n/p homojunction GaAs cell is found to be more radiation resistant than p/nheteroface GaAs under 10 MeV proton irradiation. Both GaAs cell types outperform conventional silicon n/p cells under the same conditions. An increase temperature dependency of maximum power for the GaAs n/p cells is attributed largely to differences in Voc between the two GaAs cell types. These results and diffusion length considerations are consistent with the conclusion that p-type GaAs is more radiation resistant than n-type and therefore that the n/p configuration is possibly favored for use in the space radiation environment. However, it is concluded that additional work is required in order to choose between the two GaAs cell configurations.

  1. SU-E-J-247: A Simulation of X-Ray Emission with Gold Nanoparticle Irradiated by Energetic Proton Beam

    SciTech Connect

    Newpower, M; Ahmad, S; Chen, Y

    2014-06-01

    Purpose: To investigate the proton induced X-ray emissions in gold-water mixture materials. Methods: In this study a Monte Carlo simulation was created using the GEANT4 toolkit (version 4.9.6). The geometry in this setup includes a 2 cm × 2 cm × 2 cm target, a scoring sphere (radius = 10 cm) and a 65 MeV planar proton source (2 cm × 2 cm). Four concentrations of a gold-water solution were irradiated with 5×10{sup 5} incident protons at a distance of 0.5 cm perpendicular to the surface of the target. The solutions of gold-water mixture had 10%, 5%, 1% and 0.5% of gold by mass, respectively. The number of photon emitting for the target was counted in the scoring sphere for the energy range of 0-86.0 keV in 0.1 keV bins. For this study the reference physics list PhysListEmStandard was used together with the x-ray fluorescence, Auger electron and PIXE (particle induced xray emission) options enabled. The range cuts for photons and electrons were set at 0.5 mm and 1.0 mm, respectively. Results: In the energy spectra of emitting X-ray fluorescence, peaks from gold K shell characteristic x-rays (68.8 and 66.9 keV) were observed. The number of counts under the peaks of Ka1 and Ka2 was found to increase with the increasing of the gold concentrations in the mixture materials. The X-ray yields (for both Ka1 and Ka2) when fitted with least-square method as a function of gold concentration demonstrate a linear dependency with R{sup 2} > 0.96. The Ka1yield per incident proton was found to be 0.0016 for 10% gold-water mixture solutions. Conclusion: This preliminary study with PIXE technique with gold nanoparticle has demonstrated potentials for its utilization in the development of range and dose verification methodology that is currently of great interest in the field of proton radiation therapy.

  2. Theoretical study of interactions between 2,2-Bis (ethylferrocenyl) propane and ammonium perchlorate at low temperature

    NASA Astrophysics Data System (ADS)

    Zhou, Junhong; Zhang, Wei; Yang, Jun; Jiang, Benzheng; Chen, Weiming

    2016-05-01

    In order to explore the interaction mechanism between 2,2-Bis (ethylferrocenyl) propane (GFP) and ammonium perchlorate (AP) at low temperature (below 250 °C), all the possible intermolecular interactions between GFP and AP were calculated. The calculations were performed in single molecule, cluster and slab models. The calculation results show that the interactions between GFP and AP at low temperature mainly come from GFP-H+ and GFP-NH4+ pair interactions. We speculate that the interaction mechanism between GFP and AP at low temperature is that GFP/H+ or GFP/NH4+ interactions cause GFP to be protonated, and then protonated GFP is to further oxidized.

  3. Ranibizumab for the Prevention of Radiation Complications in Patients Treated With Proton Beam Irradiation for Choroidal Melanoma

    PubMed Central

    Kim, Ivana K.; Lane, Anne Marie; Jain, Purva; Awh, Caroline; Gragoudas, Evangelos S.

    2016-01-01

    Purpose: To investigate the safety and potential efficacy of ranibizumab for prevention of radiation complications in patients treated with proton irradiation for choroidal melanoma Methods: Forty patients with tumors located within 2 disc diameters of the optic nerve and/or macula were enrolled in this open-label study. Participants received ranibizumab 0.5 mg or 1.0 mg at tumor localization and every 2 months thereafter for the study duration of 24 months. The incidence of adverse events, visual acuity, and other measures of ocular morbidity related to radiation complications were assessed. Historical controls with similar follow-up meeting the eligibility criteria for tumor size, location, and baseline visual acuity were assembled for comparison. Results: Fifteen patients with large tumors and 25 patients with small/medium tumors were enrolled. Thirty-two patients completed the month 24 visit. No serious ocular or systemic adverse events related to ranibizumab were observed. At 24 months, the proportion of patients with visual acuity ≥ 20/200 was 30/31 (97%) in the study group versus 92/205 (45%) in historical controls (P < .001). The proportion of patients with visual acuity ≥20/40 was 24/31 (77%) in the study group versus 46/205 (22%) in controls at 24 months (P<.001). Clinical evidence of radiation maculopathy at month 24 was seen in 8/24 (33%) patients with small/medium tumors versus 42/62 (68%) of controls (P = .004). Three patients with large tumors developed metastases. Conclusions: In this small pilot study, prophylactic ranibizumab appears generally safe in patients treated with proton irradiation for choroidal melanoma. High rates of visual acuity retention were observed through 2 years.

  4. TH-C-BRD-12: Robust Intensity Modulated Proton Therapy Plan Can Eliminate Junction Shifts for Craniospinal Irradiation

    SciTech Connect

    Liao, L; Jiang, S; Li, Y; Wang, X; Li, H; Zhu, X; Sahoo, N; Gillin, M; Mahajan, A; Grosshans, D; Zhang, X; Lim, G

    2014-06-15

    Purpose: The passive scattering proton therapy (PSPT) technique is the commonly used radiotherapy technique for craniospinal irradiation (CSI). However, PSPT involves many numbers of junction shifts applied over the course of treatment to reduce the cold and hot regions caused by field mismatching. In this work, we introduced a robust planning approach to develop an optimal and clinical efficient techniques for CSI using intensity modulated proton therapy (IMPT) so that junction shifts can essentially be eliminated. Methods: The intra-fractional uncertainty, in which two overlapping fields shift in the opposite directions along the craniospinal axis, are incorporated into the robust optimization algorithm. Treatment plans with junction sizes 3,5,10,15,20,25 cm were designed and compared with the plan designed using the non-robust optimization. Robustness of the plans were evaluated based on dose profiles along the craniospinal axis for the plans applying 3 mm intra-fractional shift. The dose intra-fraction variations (DIV) at the junction are used to evaluate the robustness of the plans. Results: The DIVs are 7.9%, 6.3%, 5.0%, 3.8%, 2.8% and 2.2%, for the robustly optimized plans with junction sizes 3,5,10,15,20,25 cm. The DIV are 10% for the non-robustly optimized plans with junction size 25 cm. The dose profiles along the craniospinal axis exhibit gradual and tapered dose distribution. Using DIVs less than 5% as maximum acceptable intrafractional variation, the overlapping region can be reduced to 10 cm, leading to potential reduced number of the fields. The DIVs are less than 5% for 5 mm intra-fractional shifts with junction size 25 cm, leading to potential no-junction-shift for CSI using IMPT. Conclusion: This work is the first report of the robust optimization on CSI based on IMPT. We demonstrate that robust optimization can lead to much efficient carniospinal irradiation by eliminating the junction shifts.

  5. A comparison of 4 MeV Proton and Co-60 gamma irradiation induced degradation in the electrical characteristics of N-channel MOSFETs

    NASA Astrophysics Data System (ADS)

    Anjum, Arshiya; Vinayakprasanna, N. H.; Pradeep, T. M.; Pushpa, N.; Krishna, J. B. M.; Gnana Prakash, A. P.

    2016-07-01

    N-channel depletion MOSFETs were irradiated with 4 MeV Proton and Co-60 gamma radiation in the dose range of 100 krad(Si) to 100 Mrad(Si). The electrical characteristics of MOSFET such as threshold voltage (Vth), density of interface trapped charges (ΔNit), density of oxide trapped charges (ΔNot), transconductance (gm), mobility (μ), leakage current (IL) and drain saturation current (ID Sat) were studied as a function of dose. A considerable increase in ΔNit and ΔNot and decrease in Vth,gm, μ, and ID Sat was observed after irradiation. The results of 4 MeV Proton irradiation were compared with that of Co-60 gamma radiation and it is found that the degradation is more for the devices irradiated with 4 MeV Protons when compared with the Co-60 gamma radiation. This indicates that Protons induce more trapped charges in the field oxide region when compared to the gamma radiation.

  6. Chemical isolation of .sup.82 Sr from proton-irradiated Mo targets

    DOEpatents

    Grant, Patrick M.; Kahn, Milton; O'Brien, Jr., Harold A.

    1976-01-01

    Spallation reactions are induced in Mo targets with 200-800 MeV protons to produce microcurie to millicurie amounts of a variety of radionuclides. A six-step radiochemical procedure, incorporating precipitation, solvent extractions, and ion exchange techniques, has been developed for the separation and purification of Sr radioactivities from other spallation products and the bulk target material. Radiostrontium can be quantitatively recovered in a sufficiently decontaminated state for use in biomedical generator development.

  7. Degradation mechanisms of 2 MeV proton irradiated AlGaN/GaN HEMTs

    SciTech Connect

    Greenlee, Jordan D. Anderson, Travis J.; Koehler, Andrew D.; Weaver, Bradley D.; Kub, Francis J.; Hobart, Karl D.; Specht, Petra; Dubon, Oscar D.; Luysberg, Martina; Weatherford, Todd R.

    2015-08-24

    Proton-induced damage in AlGaN/GaN HEMTs was investigated using energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM), and simulated using a Monte Carlo technique. The results were correlated to electrical degradation using Hall measurements. It was determined by EDS that the interface between GaN and AlGaN in the irradiated HEMT was broadened by 2.2 nm, as estimated by the width of the Al EDS signal compared to the as-grown interface. The simulation results show a similar Al broadening effect. The extent of interfacial roughening was examined using high resolution TEM. At a 2 MeV proton fluence of 6 × 10{sup 14} H{sup +}/cm{sup 2}, the electrical effects associated with the Al broadening and surface roughening include a degradation of the ON-resistance and a decrease in the electron mobility and 2DEG sheet carrier density by 28.9% and 12.1%, respectively.

  8. Effects of proton irradiation and temperature on 1 ohm-cm and 10 ohm-cm silicon solar cells

    NASA Technical Reports Server (NTRS)

    Nicoletta, C. A.

    1973-01-01

    The 1 ohm-cm and 10 ohm-cm silicon solar cells were exposed to 1.0 MeV protons at a fixed flux of 10 to the 9th power P/sq cm-sec and fluences of 10 to the 10th power, 10 to the 11th power, 10 to the 12th power and 3 X 10 to the 12th power P/sq cm. I-V curves of the cells were made at room temperature, 65 C and 165 C after each irradiation. A value of 139.5 mw/sq cm was taken as AMO incident energy rate per unit area. Degradation occurred for both uncovered 1 ohm-cm and 10 ohm-cm cells. Efficiencies are generally higher than those of comparable U.S. cells tested earlier. Damage (loss in maximum power efficiency) with proton fluence is somewhat higher for 10 ohm-cm cells, measured at the three temperatures, for fluences above 2 X 10 to the 11th power P/sq cm. Cell efficiency, as expected, changes drastically with temperature.

  9. Functional outcome of patients with benign meningioma treated by 3D conformal irradiation with a combination of photons and protons

    SciTech Connect

    Noel, Georges . E-mail: noel@ipno.in2p3.fr; Bollet, Marc A.; Calugaru, Valentin; Feuvret, Loic; Haie-Meder, Christine; Dhermain, Frederic; Ferrand, Regis; Boisserie, Gilbert; Beaudre, Anne; Mazeron, Jean-Jacques; Habrand, Jean-Louis

    2005-08-01

    Purpose: To evaluate efficacy and tolerance of external fractionated combination of photon and proton radiation therapy (RT) for intracranial benign meningiomas. Methods and Materials: Between 1994 and 2002, 51 patients with intracranial meningiomas of the base of the skull were treated with a combination of photon and proton RT. Median total dose was 60.6 cobalt Gy equivalent (54-64). One hundred eight eye-related symptoms were collected; 80 other symptoms were noted and followed up. Results: Mean follow-up was 25.4 months. Acute tolerance was excellent. Out of the 108 eye-related symptoms, 106 (96%) were evaluated. Improvements were reported for 73 (68.8%) of them. Out of the 88 other miscellaneous symptoms, 81 (92%) were evaluated. Improvements were reported in 54 cases (67%). Median time to improvement ranged from 1 to 24 months after completion of the radiotherapy, depending on the symptom. We did not observe any worsening of primary clinical signs. Radiologically, 1 patient relapsed 4 months after the end of irradiation. Pathology revealed a malignant (Grade 3) transformation of the initial Grade 1 meningioma. Four-year local control and overall survival rates were, respectively, 98% and 100%. Stabilization of the tumor was observed in 38 cases (72%), volume reduction in 10 cases (20%), and intratumor necrosis in 3 cases. Two patients complained of Grade 3 side effects: 1 unilateral hearing loss requiring aid and 1 case of complete pituitary deficiency. Conclusion: These results stressed the clinical efficacy of fractionated-associated photon-proton RT in the treatment of meningiomas, especially on cranial nerve palsies, without severe toxicity in almost all patients.

  10. Stepped-anneal and total helium/hydrogen measurements in high-energy proton-irradiated tungsten

    SciTech Connect

    Oliver, B.M.; Hamilton, M.L.; Garner, F.A.; Sommer, W.F.; Maloy, S.A.; Ferguson, P.D.

    1998-12-31

    To provide structural material design data for the Accelerator Production of Tritium (APT) project, a 1 mA, 800 MeV proton beam at the Los Alamos Neutron Science Center (LANSCE) was used to irradiate a large number of metal samples, including a tungsten target similar to that being considered as the neutron source for the tritium production. The maximum proton fluence to the tungsten target was {approximately} 10{sup 21} protons/cm{sup 2}. An unavoidable byproduct of spallation reactions is the formation of large amounts of hydrogen and helium. Postulated accident scenarios for APT involving the use of tungsten rods clad with Alloy 718, raise concerns as to the amount and rate of release of these gases due to temperatures increases from afterheat accumulation, with the major concern being pressurizing and possibly failure of the cladding. To address these issues, portions of the LANSCE tungsten rods were subjected to temperature histories calculated as likely to occur, and the time-dependent evolution of helium and hydrogen gases was measured. Stepped-anneal and total helium/hydrogen measurements were conducted on multiple samples of the tungsten material. Helium measurements were conducted at Pacific Northwest National Laboratory (PNNL) using a high-sensitivity magnetic-sector isotope-dilution helium analysis system. Stepped-anneal measurements were conducted at temperatures from {approximately} 25 C to {approximately} 1,600 C in {approximately} 100 C steps. Total helium measurements were conducted by rapid vaporization after completion of the stepped-anneal process, and are compared with Monte Carlo calculations performed at Los Alamos National Laboratory (LANL) using the LAHET code system. Hydrogen measurements were conducted between {approximately} 750 C and {approximately} 1,200 C using a high-temperature furnace that had been extensively modified for the application. Hydrogen detection was accomplished by periodic sampling of the furnace gas using a separate

  11. Recombinant human manganese superoxide dismutase (rMnSOD): a positive effect on the immunohematological state of mice irradiated with protons

    NASA Astrophysics Data System (ADS)

    Ambesi-Impiombato, Francesco Saverio; Belov, Oleg; Bulinina, Taisia; Ivanov, Alexander; Mancini, Aldo; Borrelli, Antonella; Krasavin, Eugene A.

    Protons represent the largest component of space radiation. In this regard screening of radioprotective drugs capable of increasing radioresistance of astronauts obligatory includes studying these compounds using proton radiation injury models. The recombinant human manganese superoxide dismutase (rMnSOD) had previously demonstrated its efficacy on an in vivo X-ray induced injury model, when multiple intraperitoneal treatments allowed the survival of mice irradiated with doses which were lethal for the control animals (Borrelli A et al. “A recombinant MnSOD is radioprotective for normal cells and radiosensitizing for tumor cells”. Free Radic Biol Med. 2009, 46, 110-6). Using the model of sublethal whole-body irradiation with protons available at Phasotron of Joint Institute for Nuclear Research (Dubna, Russia), we reconstruct the bone-marrow form of the acute radiation sickness to test the radioprotective effect of rMnSOD. Male (CBAxC57Bl6) F1 hybrid SPF mice weighting approximately 24 g were exposed to 171 MeV protons at the dose of 4 Gy. After irradiation, the sixfold daily subcutaneous treatment with rMnSOD has provided a statistically significant acceleration of the recovery of thymus and spleen mass and of the number of leukocytes in mice peripheral blood. In the control, untreated and irradiated mice, these positive effects were not observed even on day 7 after exposure. The number of karyocytes in bone marrow of irradiated mice has even exceeded its basal level in the control group 7 days after irradiation. The rMnSOD-treated group has thus demonstrated a significant hyper-restoration of this characteristic. In the presentation, several possibilities of using of rMnSOD in space medicine will be discussed, taking into account various biomedically relevant effects of this enzyme.

  12. Metabolic responses to low temperature in fish muscle.

    PubMed

    Guderley, Helga

    2004-05-01

    rates of mitochondrial respiration which would in turn enhance the formation of reactive oxygen species (ROS), increase proton leak and favour peroxidation of these membranes. Minimisation of mitochondrial oxidative capacities in organisms living at low temperatures would reduce such damage. PMID:15191230

  13. Metabolic responses to low temperature in fish muscle.

    PubMed

    Guderley, Helga

    2004-05-01

    rates of mitochondrial respiration which would in turn enhance the formation of reactive oxygen species (ROS), increase proton leak and favour peroxidation of these membranes. Minimisation of mitochondrial oxidative capacities in organisms living at low temperatures would reduce such damage.

  14. Manufacturing Demonstration Facility: Low Temperature Materials Synthesis

    SciTech Connect

    Graham, David E.; Moon, Ji-Won; Armstrong, Beth L.; Datskos, Panos G.; Duty, Chad E.; Gresback, Ryan; Ivanov, Ilia N.; Jacobs, Christopher B.; Jellison, Gerald Earle; Jang, Gyoung Gug; Joshi, Pooran C.; Jung, Hyunsung; Meyer, III, Harry M.; Phelps, Tommy

    2015-06-30

    The Manufacturing Demonstration Facility (MDF) low temperature materials synthesis project was established to demonstrate a scalable and sustainable process to produce nanoparticles (NPs) for advanced manufacturing. Previous methods to chemically synthesize NPs typically required expensive, high-purity inorganic chemical reagents, organic solvents and high temperatures. These processes were typically applied at small laboratory scales at yields sufficient for NP characterization, but insufficient to support roll-to-roll processing efforts or device fabrication. The new NanoFermentation processes described here operated at a low temperature (~60 C) in low-cost, aqueous media using bacteria that produce extracellular NPs with controlled size and elemental stoichiometry. Up-scaling activities successfully demonstrated high NP yields and quality in a 900-L pilot-scale reactor, establishing this NanoFermentation process as a competitive biomanufacturing strategy to produce NPs for advanced manufacturing of power electronics, solid-state lighting and sensors.

  15. Cyclic and low temperature effects on microcircuits

    NASA Technical Reports Server (NTRS)

    Weissflug, V. A.; Sisul, E. V.

    1977-01-01

    Cyclic temperature and low temperature operating life tests, and pre-/post-life device evaluations were used to determine the degrading effects of thermal environments on microcircuit reliability. Low power transistor-transistor-logic gates and linear devices were included in each test group. Device metallization systems included aluminum metallization/aluminum wire, aluminum metallization/gold wire, and gold metallization/gold wire. Fewer than 2% electrical failures were observed during the cyclic and low temperature life tests and the post-life evaluations revealed approximately 2% bond pull failures. Reconstruction of aluminum die metallization was observed in all devices and the severity of the reconstruction appeared to be directly related to the magnitude of the temperature excursion. All types of bonds except the gold/gold bonds were weakened by exposure to repeated cyclic temperature stress.

  16. Dark Current Degradation of Near Infrared Avalanche Photodiodes from Proton Irradiation

    NASA Technical Reports Server (NTRS)

    Becker, Heidi N.; Johnston, Allan H.

    2004-01-01

    InGaAs and Ge avalanche photodiodes (APDs) are examined for the effects of 63-MeV protons on dark current. Dark current increases were large and similar to prior results for silicon APDs, despite the smaller size of InGaAs and Ge devices. Bulk dark current increases from displacement damage in the depletion regions appeared to be the dominant contributor to overall dark current degradation. Differences in displacement damage factors are discussed as they relate to structural and material differences between devices.

  17. Thermodynamic power stations at low temperatures

    NASA Astrophysics Data System (ADS)

    Malherbe, J.; Ployart, R.; Alleau, T.; Bandelier, P.; Lauro, F.

    The development of low-temperature thermodynamic power stations using solar energy is considered, with special attention given to the choice of the thermodynamic cycle (Rankine), working fluids (frigorific halogen compounds), and heat exchangers. Thermomechanical conversion machines, such as ac motors and rotating volumetric motors are discussed. A system is recommended for the use of solar energy for irrigation and pumping in remote areas. Other applications include the production of cold of fresh water from brackish waters, and energy recovery from hot springs.

  18. Low-Temperature Spacecraft: Challenges/Opportunities

    NASA Astrophysics Data System (ADS)

    Dickman, J. E.; Patterson, R. L.; Overton, E.; Hammoud, A. N.; Gerber, S. S.

    2001-01-01

    Imagine sending a spacecraft into deep space that operates at the ambient temperature of its environment rather than hundreds of degrees Kelvin warmer. The average temperature of a spacecraft warmed only by the sun drops from 279 K near the Earth's orbit to 90 K near the orbit of Saturn, and to 44 K near Pluto's orbit. At present, deep space probes struggle to maintain an operating temperature near 300 K for the onboard electronics. To warm the electronics without consuming vast amounts of electrical energy, radioisotope heater units (RHUs) are used in vast numbers. Unfortunately, since RHU are always 'on', an active thermal management system is required to reject the excess heat. A spacecraft designed to operate at cryogenic temperatures and shielded from the sun by a large communication dish or solar cell array could be less complex, lighter, and cheaper than current deep space probes. Before a complete low-temperature spacecraft becomes a reality, there are several challenges to be met. Reliable cryogenic power electronics is one of the major challenges. The Low-Temperature Power Electronics Research Group at NASA Glenn Research Center (GRC) has demonstrated the ability of some commercial off the shelf power electronic components to operate at temperatures approaching that of liquid nitrogen (77 K). Below 77 K, there exists an opportunity for the development of reliable semiconductor power switching technologies other than bulk silicon CMOS. This paper will report on the results of NASA GRC's Low-Temperature Power Electronics Program and discuss the challenges to (opportunities for) the creation of a low-temperature spacecraft.

  19. Low-Temperature Hydrothermal Resource Potential

    DOE Data Explorer

    Katherine Young

    2016-06-30

    Compilation of data (spreadsheet and shapefiles) for several low-temperature resource types, including isolated springs and wells, delineated area convection systems, sedimentary basins and coastal plains sedimentary systems. For each system, we include estimates of the accessible resource base, mean extractable resource and beneficial heat. Data compiled from USGS and other sources. The paper (submitted to GRC 2016) describing the methodology and analysis is also included.

  20. Low-Temperature Hydrothermal Resource Potential Estimate

    DOE Data Explorer

    Katherine Young

    2016-06-30

    Compilation of data (spreadsheet and shapefiles) for several low-temperature resource types, including isolated springs and wells, delineated area convection systems, sedimentary basins and coastal plains sedimentary systems. For each system, we include estimates of the accessible resource base, mean extractable resource and beneficial heat. Data compiled from USGS and other sources. The paper (submitted to GRC 2016) describing the methodology and analysis is also included.

  1. Dynamical States of Low Temperature Cirrus

    NASA Technical Reports Server (NTRS)

    Barahona, D.; Nenes, A.

    2011-01-01

    Low ice crystal concentration and sustained in-cloud supersaturation, commonly found in cloud observations at low temperature, challenge our understanding of cirrus formation. Heterogeneous freezing from effloresced ammonium sulfate, glassy aerosol, dust and black carbon are proposed to cause these phenomena; this requires low updrafts for cirrus characteristics to agree with observations and is at odds with the gravity wave spectrum in the upper troposphere. Background temperature fluctuations however can establish a dynamical equilibrium between ice production and sedimentation loss (as opposed to ice crystal formation during the first stages of cloud evolution and subsequent slow cloud decay) that explains low temperature cirrus properties. This newly-discovered state is favored at low temperatures and does not require heterogeneous nucleation to occur (the presence of ice nuclei can however facilitate its onset). Our understanding of cirrus clouds and their role in anthropogenic climate change is reshaped, as the type of dynamical forcing will set these clouds in one of two preferred microphysical regimes with very different susceptibility to aerosol.

  2. Induction and Rejoining of DNA Double Strand Breaks Assessed by H2AX Phosphorylation in Melanoma Cells Irradiated with Proton and Lithium Beams

    SciTech Connect

    Ibanez, Irene L.; Bracalente, Candelaria; Molinari, Beatriz L.; Palmieri, Monica A.; Policastro, Lucia; Kreiner, Andres J.; Burlon, Alejandro A.; Valda, Alejandro; Navalesi, Daniela; Davidson, Jorge; Davidson, Miguel; Vazquez, Monica; Ozafran, Mabel; Duran, Hebe

    2009-07-15

    Purpose: The aim of this study was to evaluate the induction and rejoining of DNA double strand breaks (DSBs) in melanoma cells exposed to low and high linear energy transfer (LET) radiation. Methods and Materials: DSBs and survival were determined as a function of dose in melanoma cells (B16-F0) irradiated with monoenergetic proton and lithium beams and with a gamma source. Survival curves were obtained by clonogenic assay and fitted to the linear-quadratic model. DSBs were evaluated by the detection of phosphorylated histone H2AX ({gamma}H2AX) foci at 30 min and 6 h post-irradiation. Results: Survival curves showed the increasing effectiveness of radiation as a function of LET. {gamma}H2AX labeling showed an increase in the number of foci vs. dose for all the radiations evaluated. A decrease in the number of foci was found at 6 h post-irradiation for low LET radiation, revealing the repair capacity of DSBs. An increase in the size of {gamma}H2AX foci in cells irradiated with lithium beams was found, as compared with gamma and proton irradiations, which could be attributed to the clusters of DSBs induced by high LET radiation. Foci size increased at 6 h post-irradiation for lithium and proton irradiations in relation with persistent DSBs, showing a correlation with surviving fraction. Conclusions: Our results showed the response of B16-F0 cells to charged particle beams evaluated by the detection of {gamma}H2AX foci. We conclude that {gamma}H2AX foci size is an accurate parameter to correlate the rejoining of DSBs induced by different LET radiations and radiosensitivity.

  3. Calculations of the displacement damage and short-circuit current degradation in proton irradiated (AlGa)As-GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Yeh, C. S.; Li, S. S.; Loo, R. Y.

    1987-01-01

    A theoretical model for computing the displacement damage defect density and the short-circuit current (I sub sc) degradation in proton-irradiated (AlGa)As-GaAs p-n junction solar cells is presented. Assumptions were made with justification that the radiation induced displacement defects form an effective recombination center which controls the electron and hole lifetimes in the junction space charge region and in the n-GaAs active layer of the irradiated GaAs p-n junction cells. The degradation of I sub sc in the (AlGa)As layer was found to be negligible compared to the total degradation. In order to determine the I sub sc degradation, the displacement defect density, path length, range, reduced energy after penetrating a distance x, and the average number of displacements formed by one proton scattering event were first calculated. The I sub sc degradation was calculated by using the electron capture cross section in the p-diffused layer and the hole capture cross section in the n-base layer as well as the wavelength dependent absorption coefficients. Excellent agreement was found between the researchers calculated values and the measured I sub sc in the proton irradiated GaAs solar cells for proton energies of 100 KeV to 10 MeV and fluences from 10 to the 10th power p/square cm to 10 to the 12th power p/square cm.

  4. The Role of Non-Targeted Effects as Mediators in the Biological Effects of Proton Irradiation

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Dicello, John F.

    2006-01-01

    In recent years, the hypothesis that non-DNA targets are primary initiators and mediators of the biological effects of ionizing radiation, such as proton beams and heavy ions, has gained much interest. These phenomena have been denoted as non-targeted or bystander effects to distinguish them from the more traditionally studied model that focuses on direct damage to DNA causing chromosomal rearrangements and mutations as causative of most biological endpoints such as cell killing, tissue damage, and cancer. We review cellular and extra-cellular structures and signal transduction pathways that have been implemented in these recent studies. Non-targeted effects of interest include oxidative damage to the cytoplasm and mitochondria, disruption of the extra-cellular matrix, and modification of cytokine signaling including TGF-beta, and gap junction communication. We present an introduction to these targets and pathways, and contrast there role with DNA damage pathways.

  5. Critical current density of Nb3Sn wires after irradiation with 65MeV and 24GeV protons

    NASA Astrophysics Data System (ADS)

    Spina, T.; Scheuerlein, C.; Richter, D.; Bottura, L.; Ballarino, A.; Flükiger, R.

    2014-05-01

    Industrial Nb3Sn wires with Ti and Ta additives (RRP process) and with Ta additives (PIT process) with a diameter of 1 mm have been irradiated at room temperature with protons of 65 MeV and of 24 GeV at various fluences up to 1×1021 p/m2. A steady increase of Jc vs. fluence was observed for all the wires up to the highest fluence. The observed increase of Jc at 4.2K in all wires was quite similar in spite of the very different proton energies. With increasing fluence. the radiation induced pinning force was found to increase. the enhancement Jc/Jco after 5.04×1020 p/m2 reaching 1.4 for Ta and 1.8 for Ti alloyed wires at 10T. The present results were quantitatively analysed by assuming a radiation induced point pinning mechanism in addition to grain boundary pinning. The results are compared with those of an ongoing neutron irradiation study undertaken on the same Nb3Sn wires in collaboration with the Atominstitut Vienna. Proton irradiation was found to produce considerably higher damage than neutron irradiation.

  6. Effects of proton irradiation on a gas phase in which condensation takes place. I Negative Mg-26 anomalies and Al-26. [applied to solar and meteoritic composition

    NASA Technical Reports Server (NTRS)

    Heymann, D.; Dziczkaniec, M.; Walker, A.; Huss, G.; Morgan, J. A.

    1978-01-01

    In the present paper, isotopic effects in magnesium generated in a proton-irradiated gas phase are examined, taking only (p,n), (p,d), and (p, alpha) reactions in magnesium, aluminum, and silicon into consideration. In the presence of proton radiation, the three elements are 'removed' from the gas phase by condensation. It is required that a value of Al-26/Al-27 greater than 6 times 10 to the -5th must be reached, consistent with the value deduced by Lee Papanastassiou, and Wasserburg (1976) from their studies of the Allende meteorite. The calculations show that fast aluminum condensation reduces the required proton fluence substantially, that a significant fraction of aluminum remains uncondensed when the above value of the Al-26/Al-27 ratio is reached, that a detectable MG-24 excess is very likely to occur, that detectable negative MG-28 anomalies can be generated, and that proton fluxes and irradiation times can be varied simultaneously, and over a wide range of values, without significant changes in the required proton fluence.

  7. Power change in amorphous silicon technology by low temperature annealing

    NASA Astrophysics Data System (ADS)

    Mittal, Ankit; Rennhofer, Marcus; Dangel, Angelika; Duman, Bogdan; Schlosser, Victor

    2015-07-01

    Amorphous silicon (a-Si) is one of the best established thin-film solar-cell technologies. Despite its long history of research, it still has many critical issues because of its defect rich material and its susceptibility to degrade under light also called as Staebler-Wronski effect (SWE). This leads to an increase in the defect density of a-Si, but as a metastable effect it can be completely healed at temperatures above 170 °C. Our study is focused on investigating the behavior of annealing of different a-Si modules under low temperature conditions below 80 °C indicated by successive change of module power. These conditions reflect the environmental temperature impact of the modules in the field, or integrated in buildings as well. The power changes were followed by STC power rating and investigation of module-power evolution under low irradiance conditions at 50 W/m2. Our samples were recovered close to their initial state of power, reaching as high as 99% from its degraded value. This shows the influence of low temperature annealing and light on metastable module behavior in a-Si thin-film modules.

  8. SU-E-T-621: Analysis of Robustness of Proton Pencil Beam Scanning Technique for Delivery of Craniospinal Irradiation

    SciTech Connect

    Lin, H; Kirk, M; Zhai, H; Ding, X; Liu, H; Hill-Kayser, C; Lustig, R; Tochner, Z; McDonough, J; Both, S

    2014-06-15

    Purpose: To investigate the robustness and safety of craniospinal irradiation (CSI) planned with a proton pencil beam scanning (PBS) technique which overcomes the complexity of the planning associated with feathering match lines. Methods: Six CSI patients were planned with gradient-dose matching using PBS technique. Uniform dose coverage to the entire target volumes was achieved with averaged junction lengths of 6.9±0.3 cm. Robustness of the plans was evaluated by shifting the isocenter of each treatment field by ±3 mm in longitudinal direction and compared with the original non-shifted plan with metrics of conformity number (CN) and homogeneity index (HI). An anthropomorphic phantom study using film measurements was also carried out on a plan with 5 cm junction length. Results: For a given junction length, the dose errors were directly proportional to the setup errors. Setup errors of 3 mm from each field caused on average 3.5% lower CN and 2.1% higher HI. Minimal D95% to PTV and D98% to CTV were reduced by 2.2%±1.5% and 2.8%±1.7% respectively. A drop of maximal 6.8%±5.5% on the minimal dose to the cribriform plate was also observed. When the junction length was 5cm or longer, these 3mm setup errors from each field resulted in up to 12% dose errors. Consistent results were reached between film measurements and planned dose profiles in the junction area. Due to near-zero exit doses beyond the target volume, sparing of anterior organs such as heart, liver, lung and kidney were observed. Conclusions: Longitudinal setup errors directly reduce the dosimetric accuracy of the CSI treatment with matched proton fields. The reported technique creates a slow dose gradient in the junction area, which makes the treatment more robust and safe to longitudinal setup errors compared to conventional feathering methods.

  9. Vapor pressures of acetylene at low temperatures

    NASA Technical Reports Server (NTRS)

    Masterson, C. M.; Allen, John E., Jr.; Kraus, G. F.; Khanna, R. K.

    1990-01-01

    The atmospheres of many of the outer planets and their satellites contain a large number of hydrocarbon species. In particular, acetylene (C2H2) has been identified at Jupiter, Saturn and its satellite Titan, Uranus and Neptune. In the lower atmospheres of these planets, where colder temperatures prevail, the condensation and/or freezing of acetylene is probable. In order to obtain accurate models of the acetylene in these atmospheres, it is necessary to have a complete understanding of its vapor pressures at low temperatures. Vapor pressures at low temperatures for acetylene are being determined. The vapor pressures are measured with two different techniques in order to cover a wide range of temperatures and pressures. In the first, the acetylene is placed in a sample tube which is immersed in a low temperature solvent/liquid nitrogen slush bath whose temperature is measured with a thermocouple. The vapor pressure is then measured directly with a capacitance manometer. For lower pressures, a second technique which was called the thin-film infrared method (TFIR) was developed. It involves measuring the disappearance rate of a thin film of acetylene at a particular temperature. The spectra are then analyzed using previously determined extinction coefficient values, to determine the disappearance rate R (where R = delta n/delta t, the number of molecules that disappear per unit time). This can be related to the vapor pressure directly. This technique facilitates measurement of the lower temperatures and pressures. Both techniques have been calibrated using CO2, and have shown good agreement with the existing literature data.

  10. Production and segregation of transmutation elements Ca, Ti, Sc in the F82H steel under mixed spectrum irradiation of high energy protons and spallation neutrons

    NASA Astrophysics Data System (ADS)

    Kuksenko, Viacheslav; Pareige, Cristelle; Pareige, Philippe; Dai, Yong

    2014-04-01

    Ferritic/martensitic steel F82H was irradiated at 345 °C in a mixed proton-neutron spectrum in the Swiss spallation neutron source up to 20.3 dpa. Nanoscale investigations using the atom probe tomography (APT) technique were performed in order to study the atomic scale evolution of the microstructure of the F82H steel under irradiation. Spallation products Ca, Ti and Sc have been detected. The irradiation led to the production of about 370 appm of Ca, 90 appm of Sc and 800 appm of Ti. APT experiments revealed that regardless their low bulk concentrations, the spallation products extensively participate in the evolution of the microstructure: formation of radiation-induced clusters, segregation at the dislocation loops and alteration of the microchemistry of carbides. In this paper, a quantitative description of the observed features is presented and results are compared with TEM data of the literature obtained on the same steel and under similar irradiation conditions.

  11. Low temperature phonon anomalies in cuprates

    SciTech Connect

    Egami, T.; Petrov, Y.; McQueeney, R.J.; Shirane, G.; Endoh, Y.

    1998-08-01

    The inelastic neutron scattering measurement on La{sub 1.85}Sr{sub .15}CuO{sub 4} single crystals shows that the in-plane LO phonon dispersion at low temperature is incompatible with the current view on the dynamic charge stripes, which for this composition should have the periodicity of 4a. Instead the results are consistent with the dynamic stripes with the periodicity of 2a, half of what is expected and a quarter of the magnetic periodicity. Calculations with the two-band t-t{prime}-J model suggest that such 2a stripe charge ordering may help hole pairing.

  12. Low temperature waste form process intensification

    SciTech Connect

    Fox, K. M.; Cozzi, A. D.; Hansen, E. K.; Hill, K. A.

    2015-09-30

    This study successfully demonstrated process intensification of low temperature waste form production. Modifications were made to the dry blend composition to enable a 50% increase in waste concentration, thus allowing for a significant reduction in disposal volume and associated costs. Properties measurements showed that the advanced waste form can be produced using existing equipment and processes. Performance of the waste form was equivalent or better than the current baseline, with approximately double the amount of waste incorporation. The results demonstrate the feasibility of significantly accelerating low level waste immobilization missions across the DOE complex and at environmental remediation sites worldwide.

  13. Low temperature photoresponse of monolayer tungsten disulphide

    SciTech Connect

    Cao, Bingchen; Shen, Xiaonan; Shang, Jingzhi; Cong, Chunxiao; Yang, Weihuang; Eginligil, Mustafa E-mail: meginligil@ntu.edu.sg; Yu, Ting E-mail: meginligil@ntu.edu.sg

    2014-11-01

    High photoresponse can be achieved in monolayers of transition metal dichalcogenides. However, the response times are inconveniently limited by defects. Here, we report low temperature photoresponse of monolayer tungsten disulphide prepared by exfoliation and chemical vapour deposition (CVD) method. The exfoliated device exhibits n-type behaviour; while the CVD device exhibits intrinsic behaviour. In off state, the CVD device has four times larger ratio of photoresponse for laser on/off and photoresponse decay–rise times are 0.1 s (limited by our setup), while the exfoliated device has few seconds. These findings are discussed in terms of charge trapping and localization.

  14. Investigations of Low Temperature Time Dependent Cracking

    SciTech Connect

    Van der Sluys, W A; Robitz, E S; Young, B A; Bloom, J

    2002-09-30

    The objective of this project was to investigate metallurgical and mechanical phenomena associated with time dependent cracking of cold bent carbon steel piping at temperatures between 327 C and 360 C. Boiler piping failures have demonstrated that understanding the fundamental metallurgical and mechanical parameters controlling these failures is insufficient to eliminate it from the field. The results of the project consisted of the development of a testing methodology to reproduce low temperature time dependent cracking in laboratory specimens. This methodology was used to evaluate the cracking resistance of candidate heats in order to identify the factors that enhance cracking sensitivity. The resultant data was integrated into current available life prediction tools.

  15. The development of low temperature curing adhesives

    NASA Technical Reports Server (NTRS)

    Green, H. E.; Sutherland, J. D.; Hom, J. M.; Sheppard, C. H.

    1975-01-01

    An approach for the development of a practical low temperature (293 K-311 K/68 F-100 F) curing adhesive system based on a family of amide/ester resins was studied and demonstrated. The work was conducted on resin optimization and adhesive compounding studies. An improved preparative method was demonstrated which involved the reaction of an amine-alcohol precursor, in a DMF solution with acid chloride. Experimental studies indicated that an adhesive formulation containing aluminum powder provided the best performance when used in conjunction with a commercial primer.

  16. Proton decoupling and recoupling under double-nutation irradiation in solid-state NMR

    SciTech Connect

    Takeda, Kazuyuki Wakisaka, Asato; Takegoshi, K.

    2014-12-14

    The effect of {sup 1}H decoupling in magic-angle spinning solid-state NMR is studied under radiofrequency irradiation causing simultaneous nutations around a pair of orthogonal axes. Double-nutation with an arbitrary pair of nutation frequencies is implemented through modulation of the amplitude, phase, and frequency of the transmitting pulses. Similarity and difference of double-nutation decoupling and two-pulse phase-modulation decoupling schemes [A. E. Bennett, C. M. Rienstra, M. Auger, K. V. Lakshmi, and R. G. Griffin, J. Chem. Phys. 103, 6951–6958 (1995) and I. Scholz, P. Hodgkinson, B. H. Meier, and M. Ernst, J. Chem. Phys. 130, 114510 (2009)] are discussed. The structure of recoupling bands caused by interference of the {sup 1}H spin nutation with sample spinning is studied by both experiments and numerical simulations.

  17. SU-E-T-557: Measuring Neutron Activation of Cardiac Devices Irradiated During Proton Therapy Using Indium Foils

    SciTech Connect

    Avery, S; Christodouleas, J; Delaney, K; Diffenderfer, E; Brown, K

    2014-06-01

    Purpose: Measuring Neutron Activation of Cardiac devices Irradiated during Proton Therapy using Indium Foils Methods: The foils had dimensions of 25mm x 25mm x 1mm. After being activated, the foils were placed in a Canberra Industries well chamber utilizing a NaI(Tl) scintillation detector. The resulting gamma spectrum was acquired and analyzed using Genie 2000 spectroscopy software. One activation foil was placed over the upper, left chest of RANDO where a pacemaker would be. The rest of the foils were placed over the midline of the patient at different distances, providing a spatial distribution over the phantom. Using lasers and BBs to align the patient, 200 MU square fields were delivered to various treatment sites: the brain, the pancreas, and the prostate. Each field was shot at least a day apart, giving more than enough time for activity of the foil to decay (t1=2 = 54.12 min). Results: The net counts (minus background) of the three aforementioned peaks were used for our measurements. These counts were adjusted to account for detector efficiency, relative photon yields from decay, and the natural abundance of 115-In. The average neutron flux for the closed multi-leaf collimator irradiation was measured to be 1.62 x 106 - 0.18 x 106 cm2 s-1. An order of magnitude estimate of the flux for neutrons up to 1 keV from Diffenderfer et al. gives 3 x 106 cm2 s-1 which does agree on the order of magnitude. Conclusion: Lower energy neutrons have higher interaction cross-sections and are more likely to damage pacemakers. The thermal/slow neutron component may be enough to estimate the overall risk. The true test of the applicability of activation foils is whether or not measurements are capable of predicting cardiac device malfunction. For that, additional studies are needed to provide clinical evidence one way or the other.

  18. Electronics for Low Temperature Space Exploration Missions

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammoud, Ahmad; Elbuluk, Malik

    2007-01-01

    Exploration missions to outer planets and deep space require spacecraft, probes, and on-board data and communication systems to operate reliably and efficiently under severe harsh conditions. On-board electronics, in particular those in direct exposures to the space environment without any shielding or protection, will encounter extreme low temperature and thermal cycling in their service cycle in most of NASA s upcoming exploration missions. For example, Venus atmosphere, Jupiter atmosphere, Moon surface, Pluto orbiter, Mars, comets, Titan, Europa, and James Webb Space Telescope all involve low-temperature surroundings. Therefore, electronics for space exploration missions need to be designed for operation under such environmental conditions. There are ongoing efforts at the NASA Glenn Research Center (GRC) to establish a database on the operation and reliability of electronic devices and circuits under extreme temperature operation for space applications. This work is being performed under the Extreme Temperature Electronics Program with collaboration and support of the NASA Electronic Parts and Packaging (NEPP) Program. The results of these investigations will be used to establish safe operating areas and to identify degradation and failure modes, and the information will be disseminated to mission planners and system designers for use as tools for proper part selection and in risk mitigation. An overview of this program along with experimental data will be presented.

  19. Low temperature properties of holographic condensates

    NASA Astrophysics Data System (ADS)

    Basu, Pallab

    2011-03-01

    In the current work we study various models of holographic superconductors at low temperature. Generically the zero temperature limit of those models are solitonic solution with a zero sized horizon. Here we generalized simple version of those zero temperature solutions to small but non-zero temperature T. We confine ourselves to cases where near horizon geometry is AdS 4. At a non-zero temperature a small horizon would form deep inside this AdS 4 which does not disturb the UV physics. The resulting geometry may be matched with the zero temperature solution at an intermediate length scale. We understand this matching from separation of scales by setting up a perturbative expansion in gauge potential. We have a better analytic control in abelian case and quantities may be expressed in terms of hypergeometric function. From this we calculate low temperature behavior of various quatities like entropy, charge density and specific heat etc. We also calculate various energy gaps associated with p-wave holographic superconductor to understand the underlying pairing mechanism. The result deviates significantly from the corresponding weak coupling BCS counterpart.

  20. Antimisting kerosene: Low temperature degradation and blending

    NASA Technical Reports Server (NTRS)

    Yavrouian, A.; Parikh, P.; Sarohia, V.

    1988-01-01

    The inline filtration characteristics of freshly blended and degraded antimisting fuels (AMK) at low temperature are examined. A needle valve degrader was modified to include partial recirculation of degraded fuel and heat addition in the bypass loop. A pressure drop across the needle valve of up to 4,000 psi was used. The pressure drop across a 325 mesh filter screen placed inline with the degrader and directly downstream of the needle valve was measured as a function of time for different values of pressure drop across the needle valve. A volume flux of 1 gpm/sq in was employed based on the frontal area of the screen. It was found that, at ambient temperatures, freshly blended AMK fuel could be degraded using a single pass degradation at 4,000 psi pressure drop across the needle valve to give acceptable filterability performance. At fuel temperatures below -20 C, degradation becomes increasingly difficult and a single pass technique results in unacceptable filtration performance. Recirculation of a fraction of the degraded fuel and heat addition in the bypass loop improved low temperature degradation performance. The problem is addressed of blending the AMK additive with Jet A at various base fuel temperatures.

  1. Low Temperature Spin Structure of Gadolinium Titanate

    NASA Astrophysics Data System (ADS)

    Javanparast, Behnam; McClarty, Paul; Gingras, Michel

    2012-02-01

    Many rare earth pyrochlore oxides exhibit exotic spin configurations at low temperatures due to frustration. The nearest neighbor coupling between spins on the corner-sharing tetrahedral network generate geometrical magnetic frustration. Among these materials, gadolinium titanate (Gd2Ti2O7) is of particular interest. Its low temperature ordered phases are not yet understood theoretically. Bulk thermal measurements such as specific heat and magnetic susceptibility measurements find two phase transitions in zero external field, in agreement with simple mean field calculations. However, recent neutron scattering experiments suggest a so-called 4-k spin structure for intermediate phase and a so called canted 4-k structure for lower temperature phase that does not agree with either mean-field theory or Monte Carlo simulation which find the 1-k state and Palmer-Chalker state respectively as the lowest free energy configuration for those phases. In our work, we study the 4-k structure in detail and present a new phase diagram for dipolar Heisenberg spins on a pyrochlore lattice, certain portions of which describe gadolinium titanate.

  2. Low Temperature Reflectance Spectra of Titan Tholins

    NASA Technical Reports Server (NTRS)

    Roush, T. L.; Dalton, J. B.; Fonda, Mark (Technical Monitor)

    2001-01-01

    Compositional interpretation of remotely obtained reflectance spectra of outer solar system surfaces is achieved by a variety of methods. These include matching spectral curves, matching spectral features, quantitative spectral interpretation, and theoretical modeling of spectra. All of these approaches rely upon laboratory measurements of one kind or another. The bulk of these laboratory measurements are obtained with the sample of interest at ambient temperatures and pressures. However, surface temperatures of planets, satellites, and asteroids in the outer solar system are significantly cooler than ambient laboratory conditions on Earth. The infrared spectra of many materials change as a function of temperature. As has been recently demonstrated it is important to assess what effects colder temperatures have on spectral properties and hence, compositional interpretations. Titan tholin is a solid residue created by energetic processing of H-, C-, and N-bearing gases. Such residues can also be created by energetic processing if the gases are condensed into ices. Titan tholin has been suggested as a coloring agent for several surfaces in the outer solar system. Here we report laboratory measurements of Titan tholin at a temperature of 100 K and compare these to measurements of the same sample near room temperature. At low temperature the absorption features beyond 1 micrometer narrow slightly. At wavelengths greater than approx. 0.8 micrometer the overall reflectance of the sample decreases slightly making the sample less red at low temperatures. We will discuss the implications of the laboratory measurements for interpretation of cold outer solar system surfaces.

  3. Low Temperature Decomposition Rates for Tetraphenylborate Ion

    SciTech Connect

    Walker, D.D.

    1998-11-18

    Previous studies indicated that palladium is catalyzes rapid decomposition of alkaline tetraphenylborate slurries. Additional evidence suggest that Pd(II) reduces to Pd(0) during catalyst activation. Further use of tetraphenylborate ion in the decontamination of radioactive waste may require removal of the catalyst or cooling to temperatures at which the decomposition reaction proceeds slowly and does not adversely affect processing. Recent tests showed that tetraphenylborate did not react appreciably at 25 degrees Celsius over six months suggesting the potential to avoid the decomposition at low temperatures. The lack of reaction at low temperature could reflect very slow kinetics at the lower temperature, or may indicate a catalyst ''deactivation'' process. Previous tests in the temperature range 35 to 70 degrees Celsius provided a low precision estimate of the activation energy of the reaction with which to predict the rate of reaction at 25 percent Celsius. To understand the observations at 25 degrees Celsius, experiments must separate the catalyst activation step and the subsequent reaction with TPB. Tests described in this report represent an initial attempt to separate the two steps and determine the rate and activation energy of the reaction between active catalyst and TPB. The results of these tests indicate that the absence of reaction at 25 degrees Celsius was caused by failure to activate the catalyst or the presence of a deactivating mechanism. In the presence of activated catalyst, the decomposition reaction rate is significant.

  4. Low temperature alteration processes affecting ultramafic bodies

    USGS Publications Warehouse

    Nesbitt, H.W.; Bricker, O.P.

    1978-01-01

    At low temperatures, in the presence of an aqueous solution, olivine and orthopyroxene are not stable relative to the hydrous phases brucite, serpentine and talc. Alteration of dunite and peridotite to serpentine or steatite bodies must therefore proceed via non-equilibrium processes. The compositions of natural solutions emanating from dunites and peridotites demonstrate that the dissolution of forsterite and/or enstatite is rapid compared with the precipitation of the hydrous phases; consequently, dissolution of anhydrous minerals controls the chemistry of such solutions. In the presence of an aqueous phase, precipitation of hydrous minerals is the rate-controlling step. Brucite-bearing and -deficient serpentinites alter at low temperature by non-equilibrium processes, as evidenced by the composition of natural solutions from these bodies. The solutions approach equilibrium with the least stable hydrous phase and, as a consequence, are supersaturated with other hydrous phases. Dissolution of the least stable phase is rapid compared to precipitation of other phases, so that the dissolving mineral controls the solution chemistry. Non-equilibrium alteration of anhydrous ultramafic bodies continues until at least one anhydrous phase equilibrates with brucite, chrysotile or talc. The lowest temperature (at a given pressure) at which this happens is defined by the reaction: 3H2O + 2Mg2SiO4 ??? Mg3Si2O5(OH)4 + Mg(OH)2 (Johannes, 1968, Contrib. Mineral. Petrol. 19, 309-315) so that non-equilibrium alteration may occur well into greenschist facies metamorphic conditions. ?? 1978.

  5. The effects of electron and proton radiation on GaSb infrared solar cells

    NASA Technical Reports Server (NTRS)

    Gruenbaum, P. E.; Avery, J. E.; Fraas, L. M.

    1991-01-01

    Gallium antimonide (GaSb) infrared solar cells were exposed to 1 MeV electrons and protons up to fluences of 1 times 10(exp 15) cm (-2) and 1 times 10(exp 12) cm (-2) respectively. In between exposures, current voltage and spectral response curves were taken. The GaSb cells were found to degrade slightly less than typical GaAs cells under electron irradiation, and calculations from spectral response curves showed that the damage coefficient for the minority carrier diffusion length was 3.5 times 10(exp 8). The cells degraded faster than GaAs cells under proton irradiation. However, researchers expect the top cell and coverglass to protect the GaSb cell from most damaging protons. Some annealing of proton damage was observed at low temperatures (80 to 160 C).

  6. Oxidation of SO2 and formation of water droplets under irradiation of 20 MeV protons in N2/H2O/SO2

    NASA Astrophysics Data System (ADS)

    Tomita, Shigeo; Nakai, Yoichi; Funada, Shuhei; Tanikawa, Hideomi; Harayama, Isao; Kobara, Hitomi; Sasa, Kimikazu; Pedersen, Jens Olaf Pepke; Hvelplund, Preben

    2015-12-01

    We have performed an experiment on charged droplet formation in a humidified N2 gas with trace SO2 concentration and induced by 20 MeV proton irradiation. It is thought that SO2 reacts with the chemical species, such as OH radicals, generated through the reactions triggered by N2+ production. Both droplet number and droplet size increased with SO2 consumption for the proton irradiation. The total charged droplet numbers entering the differential mobility analyzer per unit time were proportional to the 0.68 power of the SO2 consumption. These two findings suggest that coagulation among the small droplets contributes to the formation of the droplets. The charged droplet volume detected per unit time is proportional to the SO2 consumption, which indicates that a constant amount of sulfur atoms is contained in a unit volume of droplet, regardless of different droplet-size distributions depending on the SO2 consumption.

  7. Investigation of the double exponential in the current-voltage characteristics of silicon solar cells. [proton irradiation effects on ATS 1 cells

    NASA Technical Reports Server (NTRS)

    Wolf, M.; Noel, G. T.; Stirn, R. J.

    1977-01-01

    Difficulties in relating observed current-voltage characteristics of individual silicon solar cells to their physical and material parameters were underscored by the unexpected large changes in the current-voltage characteristics telemetered back from solar cells on the ATS-1 spacecraft during their first year in synchronous orbit. Depletion region recombination was studied in cells exhibiting a clear double-exponential dark characteristic by subjecting the cells to proton irradiation. A significant change in the saturation current, an effect included in the Sah, Noyce, Shockley formulation of diode current resulting from recombination in the depletion region, was caused by the introduction of shallow levels in the depletion region by the proton irradiation. This saturation current is not attributable only to diffusion current from outside the depletion region and only its temperature dependence can clarify its origin. The current associated with the introduction of deep-lying levels did not change significantly in these experiments.

  8. Experimental study of fusion neutron and proton yields produced by petawatt-laser-irradiated D2-3He or CD4-3He clustering gases

    NASA Astrophysics Data System (ADS)

    Bang, W.; Barbui, M.; Bonasera, A.; Quevedo, H. J.; Dyer, G.; Bernstein, A. C.; Hagel, K.; Schmidt, K.; Gaul, E.; Donovan, M. E.; Consoli, F.; De Angelis, R.; Andreoli, P.; Barbarino, M.; Kimura, S.; Mazzocco, M.; Natowitz, J. B.; Ditmire, T.

    2013-09-01

    We report on experiments in which the Texas Petawatt laser irradiated a mixture of deuterium or deuterated methane clusters and helium-3 gas, generating three types of nuclear fusion reactions: D(d,3He)n, D(d,t)p, and 3He(d,p)4He. We measured the yields of fusion neutrons and protons from these reactions and found them to agree with yields based on a simple cylindrical plasma model using known cross sections and measured plasma parameters. Within our measurement errors, the fusion products were isotropically distributed. Plasma temperatures, important for the cross sections, were determined by two independent methods: (1) deuterium ion time of flight and (2) utilizing the ratio of neutron yield to proton yield from D(d,3He)n and 3He(d,p)4He reactions, respectively. This experiment produced the highest ion temperature ever achieved with laser-irradiated deuterium clusters.

  9. Trapping in proton irradiated p+-n-n+ silicon sensors at fluences anticipated at the HL-LHC outer tracker

    NASA Astrophysics Data System (ADS)

    Adam, W.; Bergauer, T.; Dragicevic, M.; Friedl, M.; Fruehwirth, R.; Hoch, M.; Hrubec, J.; Krammer, M.; Treberspurg, W.; Waltenberger, W.; Alderweireldt, S.; Beaumont, W.; Janssen, X.; Luyckx, S.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Barria, P.; Caillol, C.; Clerbaux, B.; De Lentdecker, G.; Dobur, D.; Favart, L.; Grebenyuk, A.; Lenzi, Th.; Léonard, A.; Maerschalk, Th.; Mohammadi, A.; Perniè, L.; Randle-Conde, A.; Reis, T.; Seva, T.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Wang, J.; Zenoni, F.; Abu Zeid, S.; Blekman, F.; De Bruyn, I.; D'Hondt, J.; Daci, N.; Deroover, K.; Heracleous, N.; Keaveney, J.; Lowette, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Tavernier, S.; Van Mulders, P.; Van Onsem, G.; Van Parijs, I.; Strom, D. A.; Basegmez, S.; Bruno, G.; Castello, R.; Caudron, A.; Ceard, L.; De Callatay, B.; Delaere, C.; Du Pree, T.; Forthomme, L.; Giammanco, A.; Hollar, J.; Jez, P.; Michotte, D.; Nuttens, C.; Perrini, L.; Pagano, D.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Härkönen, J.; Lampén, T.; Luukka, P.-R.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuovinen, E.; Eerola, P.; Tuuva, T.; Beaulieu, G.; Boudoul, G.; Combaret, C.; Contardo, D.; Gallbit, G.; Lumb, N.; Mathez, H.; Mirabito, L.; Perries, S.; Sabes, D.; Vander Donckt, M.; Verdier, P.; Viret, S.; Zoccarato, Y.; Agram, J.-L.; Conte, E.; Fontaine, J.-Ch.; Andrea, J.; Bloch, D.; Bonnin, C.; Brom, J.-M.; Chabert, E.; Charles, L.; Goetzmann, Ch.; Gross, L.; Hosselet, J.; Mathieu, C.; Richer, M.; Skovpen, K.; Pistone, C.; Fluegge, G.; Kuensken, A.; Geisler, M.; Pooth, O.; Stahl, A.; Autermann, C.; Edelhoff, M.; Esser, H.; Feld, L.; Karpinski, W.; Klein, K.; Lipinski, M.; Ostapchuk, A.; Pierschel, G.; Preuten, M.; Raupach, F.; Sammet, J.; Schael, S.; Schwering, G.; Wittmer, B.; Wlochal, M.; Zhukov, V.; Bartosik, N.; Behr, J.; Burgmeier, A.; Calligaris, L.; Dolinska, G.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Fluke, G.; Garay Garcia, J.; Gizhko, A.; Hansen, K.; Harb, A.; Hauk, J.; Kalogeropoulos, A.; Kleinwort, C.; Korol, I.; Lange, W.; Lohmann, W.; Mankel, R.; Maser, H.; Mittag, G.; Muhl, C.; Mussgiller, A.; Nayak, A.; Ntomari, E.; Perrey, H.; Pitzl, D.; Schroeder, M.; Seitz, C.; Spannagel, S.; Zuber, A.; Biskop, H.; Blobel, V.; Buhmann, P.; Centis-Vignali, M.; Draeger, A.-R.; Erfle, J.; Garutti, E.; Haller, J.; Hoffmann, M.; Junkes, A.; Lapsien, T.; Mättig, S.; Matysek, M.; Perieanu, A.; Poehlsen, J.; Poehlsen, T.; Scharf, Ch.; Schleper, P.; Schmidt, A.; Sola, V.; Steinbrück, G.; Wellhausen, J.; Barvich, T.; Barth, Ch.; Boegelspacher, F.; De Boer, W.; Butz, E.; Casele, M.; Colombo, F.; Dierlamm, A.; Eber, R.; Freund, B.; Hartmann, F.; Hauth, Th.; Heindl, S.; Hoffmann, K.-H.; Husemann, U.; Kornmeyer, A.; Mallows, S.; Muller, Th.; Nuernberg, A.; Printz, M.; Simonis, H. J.; Steck, P.; Weber, M.; Weiler, Th.; Bhardwaj, A.; Kumar, A.; Kumar, A.; Ranjan, K.; Bakhshiansohl, H.; Behnamian, H.; Khakzad, M.; Naseri, M.; Cariola, P.; De Robertis, G.; Fiore, L.; Franco, M.; Loddo, F.; Sala, G.; Silvestris, L.; Creanza, D.; De Palma, M.; Maggi, G.; My, S.; Selvaggi, G.; Albergo, S.; Cappello, G.; Chiorboli, M.; Costa, S.; Giordano, F.; Di Mattia, A.; Potenza, R.; Saizu, M. A.; Tricomi, A.; Tuvè, C.; Barbagli, G.; Brianzi, M.; Ciaranfi, R.; Civinini, C.; Gallo, E.; Meschini, M.; Paoletti, S.; Sguazzoni, G.; Ciulli, V.; D'Alessandro, R.; Gonzi, S.; Gori, V.; Focardi, E.; Lenzi, P.; Scarlini, E.; Tropiano, A.; Viliani, L.; Ferro, F.; Robutti, E.; Lo Vetere, M.; Gennai, S.; Malvezzi, S.; Menasce, D.; Moroni, L.; Pedrini, D.; Dinardo, M.; Fiorendi, S.; Manzoni, R. A.; Azzi, P.; Bacchetta, N.; Bisello, D.; Dall'Osso, M.; Dorigo, T.; Giubilato, P.; Pozzobon, N.; Tosi, M.; Zucchetta, A.; De Canio, F.; Gaioni, L.; Manghisoni, M.; Nodari, B.; Re, V.; Traversi, G.; Comotti, D.; Ratti, L.; Bilei, G. M.; Bissi, L.; Checcucci, B.; Magalotti, D.; Menichelli, M.; Saha, A.; Servoli, L.; Storchi, L.; Biasini, M.; Conti, E.; Ciangottini, D.; Fanò, L.; Lariccia, P.; Mantovani, G.; Passeri, D.; Placidi, P.; Salvatore, M.; Santocchia, A.; Solestizi, L. A.; Spiezia, A.; Androsov, K.; Azzurri, P.; Arezzini, S.; Bagliesi, G.; Basti, A.; Boccali, T.; Bosi, F.; Castaldi, R.; Ciampa, A.; Ciocci, M. A.; Dell'Orso, R.; Fedi, G.; Giassi, A.; Grippo, M. T.; Lomtadze, T.; Magazzu, G.; Mazzoni, E.; Minuti, M.; Moggi, A.; Moon, C. S.; Morsani, F.; Palla, F.; Palmonari, F.; Raffaelli, F.; Savoy-Navarro, A.; Serban, A. T.; Spagnolo, P.; Tenchini, R.; Venturi, A.; Verdini, P. G.; Martini, L.; Messineo, A.; Rizzi, A.; Tonelli, G.; Calzolari, F.; Donato, S.; Fiori, F.; Ligabue, F.; Vernieri, C.; Demaria, N.; Rivetti, A.; Bellan, R.; Casasso, S.; Costa, M.; Covarelli, R.; Migliore, E.; Monteil, E.; Musich, M.; Pacher, L.; Ravera, F.; Romero, A.; Solano, A.; Trapani, P.; Jaramillo Echeverria, R.; Fernandez, M.; Gomez, G.; Moya, D.; Gonzalez Sanchez, F. J.; Munoz Sanchez, F. J.; Vila, I.; Virto, A. L.; Abbaneo, D.; Ahmed, I.; Albert, E.; Auzinger, G.; Berruti, G.; Bianchi, G.; Blanchot, G.; Breuker, H.; Ceresa, D.; Christiansen, J.; Cichy, K.; Daguin, J.; D'Alfonso, M.; D'Auria, A.; Detraz, S.; De Visscher, S.; Deyrail, D.; Faccio, F.; Felici, D.; Frank, N.; Gill, K.; Giordano, D.; Harris, P.; Honma, A.; Kaplon, J.; Kornmayer, A.; Kottelat, L.; Kovacs, M.; Mannelli, M.; Marchioro, A.; Marconi, S.; Martina, S.; Mersi, S.; Michelis, S.; Moll, M.; Onnela, A.; Pakulski, T.; Pavis, S.; Peisert, A.; Pernot, J.-F.; Petagna, P.; Petrucciani, G.; Postema, H.; Rose, P.; Rzonca, M.; Stoye, M.; Tropea, P.; Troska, J.; Tsirou, A.; Vasey, F.; Vichoudis, P.; Verlaat, B.; Zwalinski, L.; Bachmair, F.; Becker, R.; Bäni, L.; di Calafiori, D.; Casal, B.; Djambazov, L.; Donega, M.; Dünser, M.; Eller, P.; Grab, C.; Hits, D.; Horisberger, U.; Hoss, J.; Kasieczka, G.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Perrozzi, L.; Roeser, U.; Rossini, M.; Starodumov, A.; Takahashi, M.; Wallny, R.; Amsler, C.; Bösiger, K.; Caminada, L.; Canelli, F.; Chiochia, V.; de Cosa, A.; Galloni, C.; Hreus, T.; Kilminster, B.; Lange, C.; Maier, R.; Ngadiuba, J.; Pinna, D.; Robmann, P.; Taroni, S.; Yang, Y.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Kaestli, H.-C.; Kotlinski, D.; Langenegger, U.; Meier, B.; Rohe, T.; Streuli, S.; Chen, P.-H.; Dietz, C.; Grundler, U.; Hou, W.-S.; Lu, R.-S.; Moya, M.; Wilken, R.; Cussans, D.; Flacher, H.; Goldstein, J.; Grimes, M.; Jacob, J.; Seif El Nasr-Storey, S.; Cole, J.; Hobson, P.; Leggat, D.; Reid, I. D.; Teodorescu, L.; Bainbridge, R.; Dauncey, P.; Fulcher, J.; Hall, G.; Magnan, A.-M.; Pesaresi, M.; Raymond, D. M.; Uchida, K.; Coughlan, J. A.; Harder, K.; Ilic, J.; Tomalin, I. R.; Garabedian, A.; Heintz, U.; Narain, M.; Nelson, J.; Sagir, S.; Speer, T.; Swanson, J.; Tersegno, D.; Watson-Daniels, J.; Chertok, M.; Conway, J.; Conway, R.; Flores, C.; Lander, R.; Pellett, D.; Ricci-Tam, F.; Squires, M.; Thomson, J.; Burt, K.; Ellison, J.; Hanson, G.; Malberti, M.; Olmedo, M.; Cerati, G.; Sharma, V.; Vartak, A.; Yagil, A.; Zevi Della Porta, G.; Dutta, V.; Gouskos, L.; Incandela, J.; Kyre, S.; McColl, N.; Mullin, S.; White, D.; Cumalat, J. P.; Ford, W. T.; Gaz, A.; Krohn, M.; Stenson, K.; Wagner, S. R.; Baldin, B.; Bolla, G.; Burkett, K.; Butler, J.; Cheung, H.; Chramowicz, J.; Christian, D.; Cooper, W. E.; Deptuch, G.; Derylo, G.; Gingu, C.; Gruenendahl, S.; Hasegawa, S.; Hoff, J.; Howell, J.; Hrycyk, M.; Jindariani, S.; Johnson, M.; Jung, A.; Joshi, U.; Kahlid, F.; Lei, C. M.; Lipton, R.; Liu, T.; Los, S.; Matulik, M.; Merkel, P.; Nahn, S.; Prosser, A.; Rivera, R.; Shenai, A.; Spiegel, L.; Tran, N.; Uplegger, L.; Voirin, E.; Yin, H.; Adams, M. R.; Berry, D. R.; Evdokimov, A.; Evdokimov, O.; Gerber, C. E.; Hofman, D. J.; Kapustka, B. K.; O'Brien, C.; Sandoval Gonzalez, D. I.; Trauger, H.; Turner, P.; Parashar, N.; Stupak, J.; Bortoletto, D.; Bubna, M.; Hinton, N.; Jones, M.; Miller, D. H.; Shi, X.; Tan, P.; Baringer, P.; Bean, A.; Benelli, G.; Gray, J.; Majumder, D.; Noonan, D.; Sanders, S.; Stringer, R.; Ivanov, A.; Makouski, M.; Skhirtladze, N.; Taylor, R.; Anderson, I.; Fehling, D.; Gritsan, A.; Maksimovic, P.; Martin, C.; Nash, K.; Osherson, M.; Swartz, M.; Xiao, M.; Acosta, J. G.; Cremaldi, L. M.; Oliveros, S.; Perera, L.; Summers, D.; Bloom, K.; Bose, S.; Claes, D. R.; Dominguez, A.; Fangmeier, C.; Gonzalez Suarez, R.; Meier, F.; Monroy, J.; Hahn, K.; Sevova, S.; Sung, K.; Trovato, M.; Bartz, E.; Duggan, D.; Halkiadakis, E.; Lath, A.; Park, M.; Schnetzer, S.; Stone, R.; Walker, M.; Malik, S.; Mendez, H.; Ramirez Vargas, J. E.; Alyari, M.; Dolen, J.; George, J.; Godshalk, A.; Iashvili, I.; Kaisen, J.; Kharchilava, A.; Kumar, A.; Rappoccio, S.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; Kaufman, G.; Mirman, N.; Ryd, A.; Salvati, E.; Skinnari, L.; Thom, J.; Thompson, J.; Tucker, J.; Winstrom, L.; Akgün, B.; Ecklund, K. M.; Nussbaum, T.; Zabel, J.; Betchart, B.; Covarelli, R.; Demina, R.; Hindrichs, O.; Petrillo, G.; Eusebi, R.; Osipenkov, I.; Perloff, A.; Ulmer, K. A.; Delannoy, A. G.; D'Angelo, P.; Johns, W.

    2016-04-01

    The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200 μm thick n-type silicon sensors are irradiated with protons of different energies to fluences of up to 3 · 1015 neq/cm2. Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determine the charge collection efficiencies separately for electrons and holes drifting through the sensor. The effective trapping rates are extracted by comparing the results to simulation. The electric field is simulated using Synopsys device simulation assuming two effective defects. The generation and drift of charge carriers are simulated in an independent simulation based on PixelAV. The effective trapping rates are determined from the measured charge collection efficiencies and the simulated and measured time-resolved current pulses are compared. The effective trapping rates determined for both electrons and holes are about 50% smaller than those obtained using standard extrapolations of studies at low fluences and suggest an improved tracker performance over initial expectations.

  10. Enhancement of the high-magnetic-field critical current density of superconducting MgB2 by proton irradiation.

    PubMed

    Bugoslavsky, Y; Cohen, L F; Perkins, G K; Polichetti, M; Tate, T J; Gwilliam, R; Caplin, A D

    2001-05-31

    Magnesium diboride, MgB2, has a relatively high superconducting transition temperature, placing it between the families of low- and high-temperature (copper oxide based) superconductors. Supercurrent flow in MgB2 is unhindered by grain boundaries, making it potentially attractive for technological applications in the temperature range 20-30 K. But in the bulk material, the critical current density (Jc) drops rapidly with increasing magnetic field strength. The magnitude and field dependence of the critical current are related to the presence of structural defects that can 'pin' the quantized magnetic vortices that permeate the material, and a lack of natural defects in MgB2 may be responsible for the rapid decline of Jc with increasing field strength. Here we show that modest levels of atomic disorder induced by proton irradiation enhance the pinning of vortices, thereby significantly increasing Jc at high field strengths. We anticipate that either chemical doping or mechanical processing should generate similar levels of disorder, and so achieve performance that is technologically attractive in an economically viable way.

  11. Far infrared spectra of amorphous and crystalline water ice and changes in these phases as the result of proton irradiation

    NASA Technical Reports Server (NTRS)

    Hudson, Reggie L.; Moore, Marla H.

    1992-01-01

    Far infrared spectra from 20 microns (500 cm(sup -1)) to 100 microns (100 cm(sup -1)) of water ice were measured. Amorphous ice deposited at 13 K has one absorption band at 45 microns (220 cm(sup -1)). Amorphous ice evolves into a crystalline form with absorptions at 44 microns (229 cm(sup -1)) and 62 microns (162 cm(sup -1)) as the temperature is increased to 155 K. Spectra documenting this phase change are presented as well as spectra of crystalline ice at temperatures between 13 K and 155 K. Far infrared spectra of amorphous and crystalline water ice before and after proton irradiation are also presented. Changes in these two forms are discussed in relation to ices in comets, grains, and planetary satellites in various radiation environments. Observations of non-terrestrial clathrate hydrates are still lacking despite the fact that clathrates first were suggested to exist in cometary and interstellar ices over forty years ago. Spectroscopy, the most direct method of astronomical detection, has been hampered by the similarity of clathrate hydrate spectra to those of unenclathrated guest molecules and solid H2O. A methanol (CH3OH) clathrate hydrate, using a recently published procedure, was prepared and its far-IR spectrum investigated. The spectrum is quite differenct from that of either unenclathrated CH3OH or solid H2O and so should be of value in astronomical searches for this clathrate.

  12. The Low Temperature Microgravity Physics Experiments Project

    NASA Technical Reports Server (NTRS)

    Holmes, Warren; Lai, Anthony; Croonquist, Arvid; Chui, Talso; Eraker, J. H.; Abbott, Randy; Mills, Gary; Mohl, James; Craig, James; Balachandra, Balu; Gannon, Jade

    2000-01-01

    The Low Temperature Microgravity Physics Facility (LTMPF) is being developed by NASA to provide long duration low temperature and microgravity environment on the International Space Station (ISS) for performing fundamental physics investigations. Currently, six experiments have been selected for flight definition studies. More will be selected in a two-year cycle, through NASA Research Announcement. This program is managed under the Low Temperature Microgravity Physics Experiments Project Office at the Jet Propulsion Laboratory. The facility is being designed to launch and returned to earth on a variety of vehicles including the HII-A and the space shuttle. On orbit, the facility will be connected to the Exposed Facility on the Japanese Experiment Module, Kibo. Features of the facility include a cryostat capable of maintaining super-fluid helium at a temperature of 1.4 K for 5 months, resistance thermometer bridges, multi-stage thermal isolation system, thermometers capable of pico-Kelvin resolution, DC SQUID magnetometers, passive vibration isolation, and magnetic shields with a shielding factor of 80dB. The electronics and software architecture incorporates two VME buses run using the VxWorks operating system. Technically challenging areas in the design effort include the following: 1) A long cryogen life that survives several launch and test cycles without the need to replace support straps for the helium tank. 2) The minimization of heat generation in the sample stage caused by launch vibration 3) The design of compact and lightweight DC SQUID electronics. 4) The minimization of RF interference for the measurement of heat at pico-Watt level. 5) Light weighting of the magnetic shields. 6) Implementation of a modular and flexible electronics and software architecture. The first launch is scheduled for mid-2003, on an H-IIA Rocket Transfer Vehicle, out of the Tanegashima Space Center of Japan. Two identical facilities will be built. While one facility is onboard

  13. Radically Different Kinetics at Low Temperatures

    NASA Astrophysics Data System (ADS)

    Sims, Ian

    2014-06-01

    The use of the CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme, or Reaction Kinetics in Uniform Supersonic Flow) technique coupled with pulsed laser photochemical kinetics methods has shown that reactions involving radicals can be very rapid at temperatures down to 10 K or below. The results have had a major impact in astrochemistry and planetology, as well as proving an exacting test for theory. The technique has also been applied to the formation of transient complexes of interest both in atmospheric chemistry and combustion. Until now, all of the chemical reactions studied in this way have taken place on attractive potential energy surfaces with no overall barrier to reaction. The F + H2 {→} HF + H reaction does possess a substantial energetic barrier ({\\cong} 800 K), and might therefore be expected to slow to a negligible rate at very low temperatures. In fact, this H-atom abstraction reaction does take place efficiently at low temperatures due entirely to tunneling. I will report direct experimental measurements of the rate of this reaction down to a temperature of 11 K, in remarkable agreement with state-of-the-art quantum reactive scattering calculations by François Lique (Université du Havre) and Millard Alexander (University of Maryland). It is thought that long chain cyanopolyyne molecules H(C2)nCN may play an important role in the formation of the orange haze layer in Titan's atmosphere. The longest carbon chain molecule observed in interstellar space, HC11N, is also a member of this series. I will present new results, obtained in collaboration with Jean-Claude Guillemin (Ecole de Chimie de Rennes) and Stephen Klippenstein (Argonne National Labs), on reactions of C2H, CN and C3N radicals (using a new LIF scheme by Hoshina and Endo which contribute to the low temperature formation of (cyano)polyynes. H. Sabbah, L. Biennier, I. R. Sims, Y. Georgievskii, S. J. Klippenstein, I. W. M. Smith, Science 317, 102 (2007). S. D. Le Picard, M

  14. Recovery of the chemical ordering in L1{sub 0} MnAl epitaxial thin films irradiated by 2 MeV protons

    SciTech Connect

    Anuniwat, Nattawut; Cui, Yishen; Wolf, Stuart A.; Lu, Jiwei; Weaver, Bradley D.

    2013-03-11

    Epitaxial MnAl films with a high chemical ordering were synthesized and characterized during a series of irradiations by 2 MeV protons (H{sup +}). The chemical ordering was first reduced to a minimum at a total fluence (TF) of 1 Multiplication-Sign 10{sup 15} H{sup +}/cm{sup 2}, and consequently was recovered at the final total fluence of 2 Multiplication-Sign 10{sup 15} H{sup +}/cm{sup 2}. We attributed the recovery of chemical ordering to thermal effects and the enhanced diffusion caused by the high energy protons. In addition, the damages by the protons have little effect on the magnetic scattering processing in MnAl characterized by the anomalous Hall effect.

  15. Database in low temperature plasma modeling

    NASA Astrophysics Data System (ADS)

    Sakai, Y.

    2002-05-01

    This article is composed of recommended sets of electron collision cross-sections and reaction cross-sections of excited species assessed by a swam method and of information on transport coefficients and reaction rates (cross-sections) of ions, which are needed in low temperature plasma modeling. These data have been piled up by the Investigation Committee on "Discharge Plasma Electron Collision Cross-sections", IEE Japan, and the author's laboratory. The gases taken for the assessment in this work are rare gases, Hg, N 2, O 2, CO 2, CF 4, CH 4, GeH 4, SiH 4, SF 6, C 2H 6, Si 2H 6, c-C 4F 8 and CCl 2F 2.

  16. Low Temperature SQUID for NDE Applications

    NASA Technical Reports Server (NTRS)

    Wincheski, Buzz (Technical Monitor); Selim, Raouf

    2003-01-01

    We have developed a low temperature SuperConducting Quantum Interference Device - SQUID measurement system for detection of defects deep under the surface of aluminum structures using eddy current techniques. The system uses a two dimensional planar inducer with two different excitation frequencies to induce a current in the sample. We have developed a data analysis software program that enabled us to distinguish between round defects (holes), straight defects (slots) and slots close to holes simulating cracks starting from rivets in aluminum structures. We were able to detect defects that are 8mm below the surface. We have also measured the change in phase of the detected signal as a function of depth of the defect. This relationship can be used to determine the depth of hidden flaws. Using this analysis software with the high temperature SQUID system at NASA Langley we were able to detect slots close to holes in layered aluminum sample.

  17. Low temperature catalyst system for methanol production

    DOEpatents

    Sapienza, R.S.; Slegeir, W.A.; O'Hare, T.E.

    1984-04-20

    This patent discloses a catalyst and process useful at low temperatures (150/sup 0/C) and preferably in the range 80 to 120/sup 0/C used in the production of methanol from carbon monoxide and hydrogen. The catalyst components are used in slurry form and comprise (1) a complex reducing agent derived from the component structure NaH-ROH-M(OAc)/sub 2/ where M is selected from the group consisting of Ni, Pd, and Co and R is a lower alkyl group containing 1 to 6 carbon atoms and (2) a metal carbonyl of a group VI (Mo, Cr, W) metal. For the first component, Nic is preferred (where M = Ni and R = tertiary amyl). For the second component, Mo(CO)/sub 6/ is preferred. The mixture is subjected to a conditioning or activating step under temperature and pressure, similar to the parameters given above, to afford the active catalyst.

  18. Low temperature catalysts for methanol production

    DOEpatents

    Sapienza, R.S.; Slegeir, W.A.; O'Hare, T.E.; Mahajan, D.

    1986-09-30

    A catalyst and process useful at low temperatures (below about 160 C) and preferably in the range 80--120 C used in the production of methanol from carbon monoxide and hydrogen are disclosed. The catalyst is used in slurry form and comprises a complex reducing agent derived from the component structure NaH--RONa-M(OAc)[sub 2] where M is selected from the group consisting of Ni, Pd, and Co and R is a lower alkyl group containing 1--6 carbon atoms. This catalyst is preferably used alone but is also effective in combination with a metal carbonyl of a group VI (Mo, Cr, W) metal. The preferred catalyst precursor is Nic (where M = Ni and R = tertiary amyl). Mo(CO)[sub 6] is the preferred metal carbonyl if such component is used. The catalyst is subjected to a conditioning or activating step under temperature and pressure, similar to the parameters given above, to afford the active catalyst.

  19. Magnetic refrigeration for low-temperature applications

    NASA Technical Reports Server (NTRS)

    Barclay, J. A.

    1985-01-01

    The application of refrigeration at low temperatures ranging from production of liquid helium for medical imaging systems to cooling of infrared sensors on surveillance satellites is discussed. Cooling below about 15 K with regenerative refrigerators is difficult because of the decreasing thermal mass of the regenerator compared to that of the working material. In order to overcome this difficulty with helium gas as the working material, a heat exchanger plus a Joule-Thomson or other exponder is used. Regenerative magnetic refrigerators with magnetic solids as the working material have the same regenerator problem as gas refrigerators. This problem provides motivation for the development of nonregenerative magnetic refrigerators that span approximately 1 K to approximately 0 K. Particular emphasis is placed on high reliability and high efficiency. Calculations indicate considerable promise in this area. The principles, the potential, the problems, and the progress towards development of successful 4 to 20 K magnetic refrigerators are discussed.

  20. Coal desulfurization by low-temperature chlorinolysis

    NASA Technical Reports Server (NTRS)

    Hsu, G. C.; Kalvinskas, J. J.; Ganguli, P. S.; Gavalas, G. R.

    1977-01-01

    Among the three principal methods for precombustion desulfurization of coal, which include physical depyriting, chemical desulfurization, and coal conversion to low-sulfur liquid and gaseous fuels, the potential of chemical methods looks promising in terms of both total sulfur removal and processing cost. The principal chemical methods for coal desulfurization involve treatment with either oxidizing agents or basic media at elevated temperature and pressure. A description is given of some recent experimental results which show the feasibility of removing sulfur, particularly organic sulfur, from high-sulfur coals by a simple method of low-temperature chlorinolysis followed by hydrolysis and dechlorination. The chemical feasibility of sulfur removal by chlorinolysis rather than the detailed engineering process is emphasized.

  1. Low-temperature geothermal resources of Washington

    SciTech Connect

    Schuster, J.E.; Bloomquist, R.G.

    1994-06-01

    This report presents information on the location, physical characteristics, and water chemistry of low-temperature geothermal resources in Washington. The database includes 941 thermal (>20C or 68F) wells, 34 thermal springs, lakes, and fumaroles, and 238 chemical analyses. Most thermal springs occur in the Cascade Range, and many are associated with stratovolcanoes. In contrast, 97 percent of thermal wells are located in the Columbia Basin of southeastern Washington. Some 83.5 percent are located in Adams, Benton, Franklin, Grant, Walla Walla, and Yakima Counties. Yakima County, with 259 thermal wells, has the most. Thermal wells do not seem to owe their origin to local sources of heat, such as cooling magma in the Earth`s upper crust, but to moderate to deep circulation of ground water in extensive aquifers of the Columbia River Basalt Group and interflow sedimentary deposits, under the influence of a moderately elevated (41C/km) average geothermal gradient.

  2. Evaluation of Low Temperature CO Removal Catalysts

    NASA Technical Reports Server (NTRS)

    Monje, Oscar

    2015-01-01

    CO removal from spacecraft gas streams was evaluated for three commercial, low temperature oxidation catalysts: Carulite 300, Sofnocat 423, and Hamilton Sundstrand Pt1. The catalysts were challenged with CO concentrations (1-100 ppm) under dry and wet (50% humidity) conditions using 2-3 % O2. CO removal and CO2 concentration were measured at constant feed composition using a FTIR. Water vapor affected the CO conversion of each catalyst differently. An initial screening found that Caulite 300 could not operate in humid conditions. The presence of water vapor affected CO conversion of Sofnocat 423 for challenge concentrations below 40 ppm. The conversion of CO by Sofnocat 423 was 80% at CO concentrations greater than 40 ppm under both dry and moist conditions. The HS Pt1 catalyst exhibited CO conversion levels of 100% under both dry and moist conditions.

  3. Automotive fuels at low temperatures. Technical digest

    SciTech Connect

    Diemand, D.

    1991-03-01

    Problems with fuels at extremely low temperatures are largely due to wax formation, increased viscosity, decreased volatility and contamination by water. This is especially true of diesel fuels, but even gasoline suffers from these problems to some extent. Some difficulties may begin to appear at temperatures above 0 deg. C. The majority of fuels are derived from petroleum crude oil. In addition, secondary processing of the crude procedures further fuel stocks from other fractions that could not otherwise be used as fuel. Cracking reduces large molecules from light gases or from the lighter products of the cracking process; polymerization is similar to alkylation but results in products with a lower octane rating; reforming catalytically alters certain low-octane substances, resulting in a high-octane product. The four basic molecular structures in petroleum oil products are aromatics, naphthenes, olefins and paraffins.

  4. Low temperature double-layer capacitors

    NASA Technical Reports Server (NTRS)

    Brandon, Erik J. (Inventor); Smart, Marshall C. (Inventor); West, William C. (Inventor)

    2011-01-01

    Double-layer capacitors capable of operating at extremely low temperatures (e.g., as low as -75.degree. C.) are disclosed. Electrolyte solutions combining a base solvent (e.g., acetonitrile) and a cosolvent are employed to lower the melting point of the base electrolyte. Example cosolvents include methyl formate, ethyl acetate, methyl acetate, propionitrile, butyronitrile, and 1,3-dioxolane. An optimized concentration (e.g., 0.10 M to 0.75 M) of salt, such as tetraethylammonium tetrafluoroborate, is dissolved into the electrolyte solution. In some cases (e.g., 1,3-dioxolane cosolvent) additives, such as 2% by volume triethylamine, may be included in the solvent mixture to prevent polymerization of the solution. Conventional device form factors and structural elements (e.g., porous carbon electrodes and a polyethylene separator) may be employed.

  5. REFRIGERATION ESPECIALLY FOR VERY LOW TEMPERATURES

    DOEpatents

    Kennedy, P.B.; Smith, H.R. Jr.

    1960-09-13

    A refrigeration system for producing very low temperatures is described. The system of the invention employs a binary mixture refrigerant in a closed constant volume, e.g., Freon and ethylene. Such mixture is compressed in the gaseous state and is then separated in a fractionating column element of the system. Thenceforth, the first liquid to separate is employed stagewise to cool and liq uefy successive portions of the refrigerant at successively lower temperatures by means of heat exchangers coupled between the successive stages. When shut down, all of the volumes of the system are interconnected and a portion of the refrigerant remains liquid at ambient temperatures so that no dangerous overpressures develop. The system is therefore rugged, simple and dependable in operation.

  6. Preparation of silver nanoparticles at low temperature

    NASA Astrophysics Data System (ADS)

    Mishra, Mini; Chauhan, Pratima

    2016-04-01

    Silver from ancient time is used as antimicrobial agent in the bulk form but now with the advancement in nanotechnology silver in the form of nanoparticles shown potential effect against microbes which make us easy to fight with many diseases plants and animals. In this work silver nanoparticles were synthesized by chemical routes using sodium borohydride as reducing agent at low temperature. The particles were characterized through UV-Visible spectroscopy as well as X-Ray Diffraction. The UV-visible spectra of silver nanoparticles exhibited absorption at 425 cm; the crystallite size of the particles is between 19nm to 39nm. EDAX graph shows two peaks of silver and oxygen. Water absorbed by silver nanoparticles was removed by the calcinations.

  7. Low-temperature thermodynamics with quantum coherence

    PubMed Central

    Narasimhachar, Varun; Gour, Gilad

    2015-01-01

    Thermal operations are an operational model of non-equilibrium quantum thermodynamics. In the absence of coherence between energy levels, exact state transition conditions under thermal operations are known in terms of a mathematical relation called thermo-majorization. But incorporating coherence has turned out to be challenging, even under the relatively tractable model wherein all Gibbs state-preserving quantum channels are included. Here we find a mathematical generalization of thermal operations at low temperatures, ‘cooling maps', for which we derive the necessary and sufficient state transition condition. Cooling maps that saturate recently discovered bounds on coherence transfer are realizable as thermal operations, motivating us to conjecture that all cooling maps are thermal operations. Cooling maps, though a less-conservative generalization to thermal operations, are more tractable than Gibbs-preserving operations, suggesting that cooling map-like models at general temperatures could be of use in gaining insight about thermal operations. PMID:26138621

  8. A symmetrical low temperature pressure transducer

    NASA Astrophysics Data System (ADS)

    Helvensteijn, B. P. M.; VanSciver, S. W.

    1990-03-01

    The design and operating characteristics of a fully differential pressure transducer are described. The device is intended for use with He II heat transfer experiments where it operates in vacuum and at low temperatures (T<4.2 K). A movable electrode is attached to two sets of miniature bellows such that the electrode position is determined by the differential pressure across the device. The movable electrode is located between two fixed electrodes, thus forming a pair of variable capacitors. A dedicated charge amplifier is used to convert the pressure induced capacitance change to an ac output voltage. The sensitivity is roughly 5 μV/Pa. For the present application, the capacitor and electronics have acceptable performance, with a mean noise level of ±5 Pa.

  9. Ion Prostate Irradiation (IPI) – a pilot study to establish the safety and feasibility of primary hypofractionated irradiation of the prostate with protons and carbon ions in a raster scan technique

    PubMed Central

    2014-01-01

    Background Due to physical characteristics, ions like protons or carbon ions can administer the dose to the target volume more efficiently than photons since the dose can be lowered at the surrounding normal tissue. Radiation biological considerations are based on the assumption that the α/β value for prostate cancer cells is 1.5 Gy, so that a biologically more effective dose could be administered due to hypofractionation without increasing risks of late effects of bladder (α/β = 4.0) and rectum (α/β = 3.9). Methods/Design The IPI study is a prospective randomized phase II study exploring the safety and feasibility of primary hypofractionated irradiation of the prostate with protons and carbon ions in a raster scan technique. The study is designed to enroll 92 patients with localized prostate cancer. Primary aim is the assessment of the safety and feasibility of the study treatment on the basis of incidence grade III and IV NCI-CTC-AE (v. 4.02) toxicity and/or the dropout of the patient from the planned therapy due to any reason. Secondary endpoints are PSA-progression free survival (PSA-PFS), overall survival (OS) and quality-of-life (QoL). Discussion This pilot study aims at the evaluation of the safety and feasibility of hypofractionated irradiation of the prostate with protons and carbon ions in prostate cancer patients in an active beam technique. Additionally, the safety results will be compared with Japanese results recently published for carbon ion irradiation. Due to the missing data of protons in this hypofractionated scheme, an in depth evaluation of the toxicity will be created to gain basic data for a following comparison study with carbon ion irradiation. Trial registration Clinical Trial Identifier: NCT01641185 (clinicaltrials.gov) PMID:24641841

  10. EUV induced low temperature SF6-based plasma

    NASA Astrophysics Data System (ADS)

    Bartnik, A.; Wachulak, P.; Fiedorowicz, H.; Skrzeczanowski, W.; Jarocki, R.; Fok, T.; Węgrzyński, Ł.

    2016-03-01

    In this work spectral investigations of low temperature F-rich photoionized plasmas were performed. The photoionized plasmas were created by irradiation of SF6 gas with intense EUV (extreme ultraviolet) radiation pulses. Two laser plasma EUV sources of different parameters used in the experiments were based on 0.8 J /4ns and 10 J/ 10 ns Nd:YAG lasers respectively. Both sources operated at 10 Hz repetition rate. The EUV radiation was focused using a dedicated reflective collector onto the gas stream, injected into a vacuum chamber synchronously with the EUV pulses. Irradiation of the SF6 gas resulted in dissociative ionization of the molecules, leading to creation of SFn+ ions and fluorine atoms. Further photo- or electron impact ionization and excitation processes allow for formation of photoionized plasmas emitting radiation in the wide spectral range. Emission spectra were measured in the EUV and optical ranges. The EUV spectra contained multiple spectral lines, originating from F II, F III and S II ions. The UV/VIS spectra were composed of spectral lines corresponding to radiative transitions in F II, F I and S II species. A computer simulation of the F II spectrum was performed using a collisional-radiative PrismSPECT code. Parameters of the photoionized plasmas were estimated by fitting the spectrum obtained from the simulations to the experimental one. Apart from that, the electron temperature was estimated employing Boltzmann plots based on the UV/VIS spectrum.

  11. The effect of low temperature cryocoolers on the development of low temperature superconducting magnets

    SciTech Connect

    Green, Michael A.

    2000-08-05

    The commercial development of reliable 4 K cryocoolers improves the future prospects for magnets made from low temperature superconductors (LTS). The hope of the developers of high temperature superconductors (HTS) has been to replace liquid helium cooled LTS magnets with HTS magnets that operate at or near liquid nitrogen temperature. There has been limited success in this endeavor, but continued problems with HTS conductors have greatly slowed progress toward this goal. The development of cryocoolers that reliably operate below 4 K will allow magnets made from LTS conductor to remain very competitive for many years to come. A key enabling technology for the use of low temperature cryocoolers on LTS magnets has been the development of HTS leads. This report describes the characteristics of LTS magnets that can be successfully melded to low-temperature cryocoolers. This report will also show when it is not appropriate to consider the use of low-temperature cryocoolers to cool magnets made with LTS conductor. A couple of specific examples of LTS magnets where cryocoolers can be used are given.

  12. Effect of proton and gamma irradiation on human lung carcinoma cells: Gene expression, cell cycle, cell death, epithelial-mesenchymal transition and cancer-stem cell trait as biological end points.

    PubMed

    Narang, Himanshi; Kumar, Amit; Bhat, Nagesh; Pandey, Badri N; Ghosh, Anu

    2015-10-01

    Proton beam therapy is a cutting edge modality over conventional gamma radiotherapy because of its physical dose deposition advantage. However, not much is known about its biological effects vis-a-vis gamma irradiation. Here we investigated the effect of proton- and gamma- irradiation on cell cycle, death, epithelial-mesenchymal transition (EMT) and "stemness" in human non-small cell lung carcinoma cells (A549). Proton beam (3MeV) was two times more cytotoxic than gamma radiation and induced higher and longer cell cycle arrest. At equivalent doses, numbers of genes responsive to proton irradiation were ten times higher than those responsive to gamma irradiation. At equitoxic doses, the proton-irradiated cells had reduced cell adhesion and migration ability as compared to the gamma-irradiated cells. It was also more effective in reducing population of Cancer Stem Cell (CSC) like cells as revealed by aldehyde dehydrogenase activity and surface phenotyping by CD44(+), a CSC marker. These results can have significant implications for proton therapy in the context of suppression of molecular and cellular processes that are fundamental to tumor expansion.

  13. Organ and effective dose conversion coefficients for a sitting female hybrid computational phantom exposed to monoenergetic protons in idealized irradiation geometries

    NASA Astrophysics Data System (ADS)

    Alves, M. C.; Santos, W. S.; Lee, Choonsik; Bolch, Wesley E.; Hunt, John G.; Carvalho Júnior, A. B.

    2014-12-01

    The conversion coefficients (CCs) relate protection quantities, mean absorbed dose (DT) and effective dose (E), with physical radiation field quantities, such as fluence (Φ). The calculation of CCs through Monte Carlo simulations is useful for estimating the dose in individuals exposed to radiation. The aim of this work was the calculation of conversion coefficients for absorbed and effective doses per fluence (DT/ Φ and E/Φ) using a sitting and standing female hybrid phantom (UFH/NCI) exposure to monoenergetic protons with energy ranging from 2 MeV to 10 GeV. The radiation transport code MCNPX was used to develop exposure scenarios implementing the female UFH/NCI phantom in sitting and standing postures. Whole-body irradiations were performed using the recommended irradiation geometries by ICRP publication 116 (AP, PA, RLAT, LLAT, ROT and ISO). In most organs, the conversion coefficients DT/Φ were similar for both postures. However, relative differences were significant for organs located in the abdominal region, such as ovaries, uterus and urinary bladder, especially in the AP, RLAT and LLAT geometries. Anatomical differences caused by changing the posture of the female UFH/NCI phantom led an attenuation of incident protons with energies below 150 MeV by the thigh of the phantom in the sitting posture, for the front-to-back irradiation, and by the arms and hands of the phantom in the standing posture, for the lateral irradiation.

  14. Organ and effective dose conversion coefficients for a sitting female hybrid computational phantom exposed to monoenergetic protons in idealized irradiation geometries.

    PubMed

    Alves, M C; Santos, W S; Lee, Choonsik; Bolch, Wesley E; Hunt, John G; Carvalho Júnior, A B

    2014-12-21

    The conversion coefficients (CCs) relate protection quantities, mean absorbed dose (DT) and effective dose (E), with physical radiation field quantities, such as fluence (Φ). The calculation of CCs through Monte Carlo simulations is useful for estimating the dose in individuals exposed to radiation. The aim of this work was the calculation of conversion coefficients for absorbed and effective doses per fluence (DT/ Φ and E/Φ) using a sitting and standing female hybrid phantom (UFH/NCI) exposure to monoenergetic protons with energy ranging from 2 MeV to 10 GeV. The radiation transport code MCNPX was used to develop exposure scenarios implementing the female UFH/NCI phantom in sitting and standing postures. Whole-body irradiations were performed using the recommended irradiation geometries by ICRP publication 116 (AP, PA, RLAT, LLAT, ROT and ISO). In most organs, the conversion coefficients DT/Φ were similar for both postures. However, relative differences were significant for organs located in the abdominal region, such as ovaries, uterus and urinary bladder, especially in the AP, RLAT and LLAT geometries. Anatomical differences caused by changing the posture of the female UFH/NCI phantom led an attenuation of incident protons with energies below 150 MeV by the thigh of the phantom in the sitting posture, for the front-to-back irradiation, and by the arms and hands of the phantom in the standing posture, for the lateral irradiation.

  15. Intensity Modulated Proton Therapy for Craniospinal Irradiation: Organ-at-Risk Exposure and a Low-Gradient Junctioning Technique

    SciTech Connect

    Stoker, Joshua B.; Grant, Jonathan; Zhu, X. Ronald; Pidikiti, Rajesh; Mahajan, Anita; Grosshans, David R.

    2014-11-01

    Purpose: To compare field junction robustness and sparing of organs at risk (OARs) during craniospinal irradiation (CSI) using intensity modulated proton therapy (IMPT) to conventional passively scattered proton therapy (PSPT). Methods and Materials: Ten patients, 5 adult and 5 pediatric patients, previously treated with PSPT-based CSI were selected for comparison. Anterior oblique cranial fields, using a superior couch rotation, and posterior spinal fields were used for IMPT planning. To facilitate low-gradient field junctioning along the spine, the inverse-planning IMPT technique was divided into 3 stages. Dose indices describing target coverage and normal tissue dose, in silico error modeling, and film dosimetry were used to assess plan quality. Results: Field junction robustness along the spine was improved using the staged IMPT planning technique, reducing the worst case impact of a 4-mm setup error from 25% in PSPT to <5% of prescription dose. This was verified by film dosimetry for clinical delivery. Exclusive of thyroid dose in adult patients, IMPT plans demonstrated sparing of organs at risk as good or better than PSPT. Coverage of the cribriform plate for pediatric (V95% [percentage of volume of the target receiving at least 95% of the prescribed dose]; 87 ± 11 vs 92 ± 7) and adult (V95%; 94 ± 7 vs 100 ± 1) patients and the clinical target in pediatric (V95%; 98 ± 2 vs 100 ± 1) and adult (V95%; 100 ± 1 vs 100 ± 1) patients for PSPT and IMPT plans, respectively, were comparable or improved. For adult patients, IMPT target dose inhomogeneity was increased, as determined by heterogeneity index (HI) and inhomogeneity coefficient (IC). IMPT lowered maximum spinal cord dose, improved spinal dose homogeneity, and reduced exposure to other OARs. Conclusions: IMPT has the potential to improve CSI plan quality and the homogeneity of intrafractional dose at match lines. The IMPT approach developed may also simplify treatments and reduce

  16. A low-temperature ZnO nanowire ethanol gas sensor prepared on plastic substrate

    NASA Astrophysics Data System (ADS)

    Lin, Chih-Hung; Chang, Shoou-Jinn; Hsueh, Ting-Jen

    2016-09-01

    In this work, a low-temperature ZnO nanowire ethanol gas sensor was prepared on plastic substrate. The operating temperature of the ZnO nanowire ethanol gas sensor was reduced to room temperature using ultraviolet illumination. The experimental results indicate a favorable sensor response at low temperature, with the best response at 60 °C. The results also reveal that the ZnO nanowire ethanol gas sensor can be easily integrated into portable products, whose waste heat can improve sensor response and achieve energy savings, while energy consumption can be further reduced by solar irradiation.

  17. Inter-Institutional Comparison of Personalized Risk Assessments for Second Malignant Neoplasms for a 13-Year-Old Girl Receiving Proton versus Photon Craniospinal Irradiation

    PubMed Central

    Taddei, Phillip J.; Khater, Nabil; Zhang, Rui; Geara, Fady B.; Mahajan, Anita; Jalbout, Wassim; Pérez-Andújar, Angélica; Youssef, Bassem; Newhauser, Wayne D.

    2015-01-01

    Children receiving radiotherapy face the probability of a subsequent malignant neoplasm (SMN). In some cases, the predicted SMN risk can be reduced by proton therapy. The purpose of this study was to apply the most comprehensive dose assessment methods to estimate the reduction in SMN risk after proton therapy vs. photon therapy for a 13-year-old girl requiring craniospinal irradiation (CSI). We reconstructed the equivalent dose throughout the patient’s body from therapeutic and stray radiation and applied SMN incidence and mortality risk models for each modality. Excluding skin cancer, the risk of incidence after proton CSI was a third of that of photon CSI. The predicted absolute SMN risks were high. For photon CSI, the SMN incidence rates greater than 10% were for thyroid, non-melanoma skin, lung, colon, stomach, and other solid cancers, and for proton CSI they were non-melanoma skin, lung, and other solid cancers. In each setting, lung cancer accounted for half the risk of mortality. In conclusion, the predicted SMN risk for a 13-year-old girl undergoing proton CSI was reduced vs. photon CSI. This study demonstrates the feasibility of inter-institutional whole-body dose and risk assessments and also serves as a model for including risk estimation in personalized cancer care. PMID:25763928

  18. Inter-Institutional Comparison of Personalized Risk Assessments for Second Malignant Neoplasms for a 13-Year-Old Girl Receiving Proton versus Photon Craniospinal Irradiation.

    PubMed

    Taddei, Phillip J; Khater, Nabil; Zhang, Rui; Geara, Fady B; Mahajan, Anita; Jalbout, Wassim; Pérez-Andújar, Angélica; Youssef, Bassem; Newhauser, Wayne D

    2015-01-01

    Children receiving radiotherapy face the probability of a subsequent malignant neoplasm (SMN). In some cases, the predicted SMN risk can be reduced by proton therapy. The purpose of this study was to apply the most comprehensive dose assessment methods to estimate the reduction in SMN risk after proton therapy vs. photon therapy for a 13-year-old girl requiring craniospinal irradiation (CSI). We reconstructed the equivalent dose throughout the patient's body from therapeutic and stray radiation and applied SMN incidence and mortality risk models for each modality. Excluding skin cancer, the risk of incidence after proton CSI was a third of that of photon CSI. The predicted absolute SMN risks were high. For photon CSI, the SMN incidence rates greater than 10% were for thyroid, non-melanoma skin, lung, colon, stomach, and other solid cancers, and for proton CSI they were non-melanoma skin, lung, and other solid cancers. In each setting, lung cancer accounted for half the risk of mortality. In conclusion, the predicted SMN risk for a 13-year-old girl undergoing proton CSI was reduced vs. photon CSI. This study demonstrates the feasibility of inter-institutional whole-body dose and risk assessments and also serves as a model for including risk estimation in personalized cancer care. PMID:25763928

  19. Modeling Low-temperature Geochemical Processes

    NASA Astrophysics Data System (ADS)

    Nordstrom, D. K.

    2003-12-01

    Geochemical modeling has become a popular and useful tool for a wide number of applications from research on the fundamental processes of water-rock interactions to regulatory requirements and decisions regarding permits for industrial and hazardous wastes. In low-temperature environments, generally thought of as those in the temperature range of 0-100 °C and close to atmospheric pressure (1 atm=1.01325 bar=101,325 Pa), complex hydrobiogeochemical reactions participate in an array of interconnected processes that affect us, and that, in turn, we affect. Understanding these complex processes often requires tools that are sufficiently sophisticated to portray multicomponent, multiphase chemical reactions yet transparent enough to reveal the main driving forces. Geochemical models are such tools. The major processes that they are required to model include mineral dissolution and precipitation; aqueous inorganic speciation and complexation; solute adsorption and desorption; ion exchange; oxidation-reduction; or redox; transformations; gas uptake or production; organic matter speciation and complexation; evaporation; dilution; water mixing; reaction during fluid flow; reaction involving biotic interactions; and photoreaction. These processes occur in rain, snow, fog, dry atmosphere, soils, bedrock weathering, streams, rivers, lakes, groundwaters, estuaries, brines, and diagenetic environments. Geochemical modeling attempts to understand the redistribution of elements and compounds, through anthropogenic and natural means, for a large range of scale from nanometer to global. "Aqueous geochemistry" and "environmental geochemistry" are often used interchangeably with "low-temperature geochemistry" to emphasize hydrologic or environmental objectives.Recognition of the strategy or philosophy behind the use of geochemical modeling is not often discussed or explicitly described. Plummer (1984, 1992) and Parkhurst and Plummer (1993) compare and contrast two approaches for

  20. Effect of proton irradiation dose on InAlN/GaN metal-oxide semiconductor high electron mobility transistors with Al2O3 gate oxide

    DOE PAGES

    Ahn, Shihyun; Kim, Byung -Jae; Lin, Yi -Hsuan; Ren, Fan; Pearton, Stephen J.; Yang, Gwangseok; Kim, Jihyun; Kravchenko, Ivan I.

    2016-07-26

    The effects of proton irradiation on the dc performance of InAlN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) with Al2O3 as the gate oxide were investigated. The InAlN/GaN MOSHEMTs were irradiated with doses ranging from 1×1013 to 1×1015cm–2 at a fixed energy of 5MeV. There was minimal damage induced in the two dimensional electron gas at the lowest irradiation dose with no measurable increase in sheet resistance, whereas a 9.7% increase of the sheet resistance was observed at the highest irradiation dose. By sharp contrast, all irradiation doses created more severe degradation in the Ohmic metal contacts, with increases of specificmore » contact resistance from 54% to 114% over the range of doses investigated. These resulted in source-drain current–voltage decreases ranging from 96 to 242 mA/mm over this dose range. The trap density determined from temperature dependent drain current subthreshold swing measurements increased from 1.6 × 1013 cm–2 V–1 for the reference MOSHEMTs to 6.7 × 1013 cm–2 V–1 for devices irradiated with the highest dose. In conclusion, the carrier removal rate was 1287 ± 64 cm–1, higher than the authors previously observed in AlGaN/GaN MOSHEMTs for the same proton energy and consistent with the lower average bond energy of the InAlN.« less