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Sample records for xe ion irradiation

  1. Interface mixing and phase transformations in Xe-ion-irradiated Co/Fe bilayers

    NASA Astrophysics Data System (ADS)

    Zhang, K.; Gupta, R.; Müller, G. A.; Schaaf, P.; Lieb, K. P.

    2004-05-01

    Bilayers of polycrystalline Co(37 nm)/Fe(37 nm) were deposited onto Si wafers via electron-gun evaporation and irradiated at room temperature with 200 keV Xe+ ions to fluences of 5×1014-1×1016/cm2. The magneto-optical Kerr effect, Rutherford backscattering spectroscopy and x-ray diffraction were used to characterize the magnetization and microstructure of the films. Xe fluences of up to 5×1015 ions/cm2 were found to induce a four-fold magnetic anisotropy in the originally isotropic films, as a consequence of the phase transformation of hexagonal Co to face-centered-cubic Co caused by ion irradiation. Xe fluences exceeding 7×1015 ions/cm2 produced a uniaxial magnetic texture, which is explained by strong Co/Fe interface mixing and possibly ion-induced formation of CoFe grains at the interface.

  2. Effect of Xe ion (167 MeV) irradiation on polycrystalline SiC implanted with Kr and Xe at room temperature

    NASA Astrophysics Data System (ADS)

    Hlatshwayo, T. T.; O’Connell, J. H.; Skuratov, V. A.; Msimanga, M.; Kuhudzai, R. J.; Njoroge, E. G.; Malherbe, J. B.

    2015-11-01

    The effect of swift heavy ion (Xe 167 MeV) irradiation on polycrystalline SiC individually implanted with 360 keV Kr and Xe ions at room temperature to fluences of 2??×??1016 cm?2 and 1??×??1016 cm?2 respectively, was investigated using transmission electron microscopy (TEM), Raman spectroscopy and Rutherford backscattering spectrometry (RBS). Implanted specimens were each irradiated with 167 MeV Xe+26 ions to a fluence of 8.3??×??1014 cm?2 at room temperature. It was observed that implantation of 360 keV Kr and Xe ions individually at room temperature amorphized the SiC from the surface up to a depth of 186 and 219?nm respectively. Swift heavy ion (SHI) irradiation reduced the amorphous layer by about 27?nm and 30?nm for the Kr and Xe samples respectively. Interestingly, the reduction in the amorphous layer was accompanied by the appearance of randomly oriented nanocrystals in the former amorphous layers after SHI irradiation in both samples. Previously, no similar nanocrystals were observed after SHI irradiations at electron stopping powers of 33 keV nm?1 and 20 keV nm?1 to fluences below 1014 cm?2. Therefore, our results suggest a fluence threshold for the formation of nanocrystals in the initial amorphous SiC after SHI irradiation. Raman results also indicated some annealing of radiation damage after swift heavy ion irradiation and the subsequent formation of small SiC crystals in the amorphous layers. No diffusion of implanted Kr and Xe was observed after swift heavy ion irradiation.

  3. Stress-induced magnetic anisotropy in Xe-ion-irradiated Ni thin films

    NASA Astrophysics Data System (ADS)

    Zhang, Kun

    2006-01-01

    Samples consisting of 75 nm Ni films deposited on Si substrates were bent mechanically and irradiated with 200 keV Xe-ions at a dose of 4 × 1014 ions/cm2. Magneto-optical Kerr effect, Rutherford backscattering spectrometry and X-ray diffraction were used to investigate the changes in the magnetic and microstructural properties. Perfect uniaxial magnetic anisotropy was found in the Ni films after irradiation and removal of the samples from the target holder. The magnetic behavior is shown to be very sensitive to the external stress produced in the films. With increasing curvature of the bent samples (?2 m-1), the easy axis of the magnetic anisotropy rotated in the direction perpendicular to the bending axis, indicating a compressive stress in the films after irradiation and relaxation.

  4. Quasi-two-dimensional Ag nanoparticle formation in silica by Xe ion irradiation and subsequent Ag ion implantation

    SciTech Connect

    Wang, Jun; Jia, Guangyi; Mu, Xiaoyu; Liu, Changlong; Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Institute of Advanced Materials Physics Faculty of Science, Tianjin 300072

    2013-04-01

    Ag nanoparticles were fabricated in silica by Xe ion irradiation and subsequent Ag ion implantation, which distributed in a depth range from 4.8 to 14.3 nm, rather than dispersed from surface to a depth of 24.7 nm when no irradiation was made in advance. In addition, the suppression of Ag implants' sputtering loss was also evidenced by a greatly increased Ag content in the prepared sample. These results are mainly due to the defect-enhanced in-beam particle growth. Further, formation of polycrystalline Ag nanoparticles was revealed, whose effect on optical absorption was discussed according to the electron mean-free-path mode.

  5. 200 keV Xe+ ions irradiation effects on Zr-Ti binary films

    NASA Astrophysics Data System (ADS)

    Wang, Weipeng; Chai, Maosheng; Feng, Wei; Li, Zhengcao; Zhang, Zhengjun

    2015-05-01

    200 keV Xenon irradiation experiments were performed on magnetron sputtered Zr-Ti films under different doses up to 9 * 1015 ions/cm2. XRD, FE-SEM, AFM, HRTEM, nano-indentation and white light interferometer characterizations were applied to study the structural and mechanical properties modification introduced by the bombardment. Upon Xenon irradiation, structure of film matrix kept stable while the crystallinity of the top surface degraded significantly. Meanwhile, properties of irradiated films such as hardness, modulus and sheet resistance evolved with the same tendency, i.e. increased firstly and decrease with further increasing the irradiation dose. By selective area irradiation, competition between the surface sputtering and swelling was revealed, by which surface defects evolution was highlighted. The micro-defects evolution during Xenon irradiation was believed to be responsible for the macro-properties' modification.

  6. Energy loss effect on color center creation in LiF crystals under irradiation with 12C, 14N, 40Ar, 84Kr, and 130Xe ions

    NASA Astrophysics Data System (ADS)

    Dauletbekova, A.; Schwartz, K.; Sorokin, M. V.; Baizhumanov, M.; Akilbekov, A.; Zdorovets, M.

    2015-09-01

    Color center creation in LiF crystals irradiated with 12C, 14N, 40Ar, 84Kr, and 130Xe MeV ions were studied as a function of the absorbed energy (fluence). For light ions (12C, 14N) the saturation of single F centers takes place at higher absorbed energy (5 × 1023 eV/cm3) than that for 40Ar, 84Kr and 130Xe ions (?1023 eV/cm3). The saturation concentration of F centers for 12C and 14N (2 × 1019 cm-3) is twice of that for the heavier ions. Further irradiation with light ions decreases concentration of F centers, presumably due to aggregation, whereas for heavy ions the saturation concentration remains approximately the same that can be explained by much stronger recombination losses within single tracks.

  7. The studies of irradiation assisted stress corrosion cracking on reactor internals stainless steel under Xe irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Rong-shan; Xu, Chao-liang; Liu, Xiang-bing; Huang, Ping; Chen, Yu

    2015-02-01

    Specimens of Chinese domestic reactor internals stainless steel were irradiated with 6 MeV Xe ions for three peak displacement damage of 2, 7 and 15 dpa at room temperature. The slow strain rate tests (SSRT), grazing incidence X-ray diffraction (GIXRD) and nano-indentation tests were carried out to study the IASCC properties, phase transition and nano-hardness variations. The SSRT results indicate that the IASCC susceptibility increases with irradiation damage. Ion irradiation accelerates the stress corrosion cracking (SCC). A new ferrite phase diffraction peak of ?(1 1 0) after irradiated to 7 dpa and another two ? phase of ?(2 0 0) and ?(2 1 1) after irradiated to 15 dpa were observed by GIXRD, which may be due to localized deformation. A similar trend of irradiation hardening and IASCC susceptibility was observed, which suggests an essential connection between them.

  8. Sputtering yields exceeding 1000 by 80 keV Xe irradiation of Au nanorods

    NASA Astrophysics Data System (ADS)

    Ilinov, A.; Kuronen, A.; Nordlund, K.; Greaves, G.; Hinks, J. A.; Busby, P.; Mellors, N. J.; Donnelly, S. E.

    2014-12-01

    Using experiments and computer simulations, we find that 80 keV Xe ion irradiation of Au nanorods can produce sputtering yields exceeding 1000, which to our knowledge are the highest yields reported for sputtering by single ions in the nuclear collision regime. This value is enhanced by more than an order of magnitude compared to the same irradiation of flat Au surfaces. Using MD simulations, we show that the very high yield can be understood as a combination of enhanced yields due to low incoming angles at the sides of the nanowire, as well as the high surface-to-volume ratio causing enhanced explosive sputtering from heat spikes. We also find, both in experiments and simulations, that channeling has a strong effect on the sputtering yield: if the incoming beam happens to be aligned with a crystal axis of the nanorod, the yield can decrease to about 100.

  9. Microstructure evolution in Xe-irradiated UO2 at room temperature

    SciTech Connect

    L.F. He; J. Pakarinen; M.A. Kirk; J. Gan; A.T. Nelson; X.-M. Bai; A. El-Azab; T.R. Allen

    2014-07-01

    In situ Transmission Electron Microscopy was conducted for single crystal UO2 to understand the microstructure evolution during 300 keV Xe irradiation at room temperature. The dislocation microstructure evolution was shown to occur as nucleation and growth of dislocation loops at low irradiation doses, followed by transformation to extended dislocation segments and tangles at higher doses. Xe bubbles with dimensions of 1-2 nm were observed after room-temperature irradiation. Electron Energy Loss Spectroscopy indicated that UO2 remained stoichiometric under room temperature Xe irradiation.

  10. Microstructure and nanoindentation of the CLAM steel with nanocrystalline grains under Xe irradiation

    NASA Astrophysics Data System (ADS)

    Chang, Yongqin; Zhang, Jing; Li, Xiaolin; Guo, Qiang; Wan, Farong; Long, Yi

    2014-12-01

    This work presents an early look at irradiation effects on China low activation martensitic (CLAM) steel with nanocrystalline grains (NC-CLAM steels) under 500 keV Xe-ion bombardment at room temperature to doses up to 5.3 displacements per atom (dpa). The microstructure in the topmost region of the steel is composed of nanocrystalline grains with an average diameter of 13 nm. As the samples were implanted at low dose, the nanocrystalline grains had martensite lath structure, and many dislocations and high density bubbles were introduced into the NC-CLAM steels. As the irradiation dose up to 5.3 dpa, a tangled dislocation network exists in the lath region, and the size of the bubbles increases. X-ray diffraction results show that the crystal quality decreases after irradiation, although the nanocrystals obviously coarsen. Grain growth under irradiation may be ascribed to the direct impact of the thermal spike on grain boundaries in the NC-CLAM steels. In irradiated samples, a compressive stress exists in the surface layer because of grain growth and irradiation-introduced defects, while the irradiation introduced grain-size coarsening and defects gradients from the surface to matrix result in a tensile stress in the irradiated NC-CLAM steels. Nanoindentation was used to estimate changes in mechanical properties during irradiation, and the results show that the hardness of the NC-CLAM steels increases with increasing irradiation dose, which was ascribed to the competition between the grain boundaries and the irradiation-introduced defects.

  11. I-Xe dating - Intercomparisons of neutron irradiations and reproducibility of the Bjurbole standard

    NASA Technical Reports Server (NTRS)

    Hohenberg, C. M.; Kennedy, B. M.

    1981-01-01

    Previously unpublished data from the stepwise heating analysis of the Valecitos 1 (V1) Bjurbole standard are presented together with the results of an isotopic dilution measurement of a KI monitor included in the V1 irradiation package. The results of these analyses are compared with the values observed in other irradiations. Apparent I-Xe 'formation' ages are reproducible for three different samples of Bjurbole, suggesting isotopic homogeneity for initial iodine in the bulk material. The systematics of neutron capture in Xe-135 (produced from U-235 neutron fission) are examined and verified in irradiated BCR-1.

  12. Calculation of Ion Charge State Distributions After Inner-Shell Ionization in Xe Atom

    SciTech Connect

    Mohammedein, Adel M.; Ghoneim, Adel A.; Kandil, Kandil M.; Kadad, Ibrahim M.

    2010-01-05

    The vacancy cascades following initial inner-shell vacancies in single and multi-ionized atoms often lead to highly charged residual ions. The inner-shell vacancy produced by ionization processes may decay by either a radiative or non-radiative transition. In addition to the vacancy filling processes, there is an electron shake off process due to the change of core potential of the atom. In the calculation of vacancy cascades, the radiative (x-ray) and non-radiative (Auger and Coster-Kronig) branching ratios give valuable information on the de-excitation dynamics of an atom with inner-shell vacancy. The production of multi-charged ions yield by the Auger cascades following inner shell ionization of an atom has been studied both experimentally and theoretically. Multi-charged Xe ions following de-excitation of K-, L{sub 1}-, L{sub 2,3}-, M{sub 1}-, M{sub 2,3}- and M{sub 4,5} subshell vacancies are calculated using Monte-Carlo algorithm to simulate the vacancy cascade development. Fluorescence yield (radiative) and Auger, Coster- Kronig yield (non- radiative) are evaluated. The decay of K hole state through radiative transitions is found to be more probable than non-radiative transitions in the first step of de-excitation. On the other hand, the decay of L, M vacancies through non-radiative transitions are more probable. The K shell ionization in Xe atom mainly yields Xe{sup 7+}, Xe{sup 8+}, Xe{sup 9+} and Xe{sup 10+} ions, and the charged X{sup 8+} ions are the highest. The main product from the L{sub 1}- shell ionization is found to be Xe{sup 8+}, Xe{sup 9+} ions, while the charged Xe{sup 8+} ions predominate at L{sub 2,3} hole states. The charged Xe{sup 6+}, Xe{sup 7+} and Xe{sup 8+} ions mainly yield from 3s{sub 1/2} and 3p{sub 1/2,3/2} ionization, while Xe in 3d{sub 3/2,5/2} hole states mainly turns into Xe{sup 4+} and Xe{sup 5+} ions. The present results are found to agree well with the experimental data.

  13. Response of GaN to energetic ion irradiation: conditions for ion track formation

    NASA Astrophysics Data System (ADS)

    Karluši?, M.; Kozubek, R.; Lebius, H.; Ban-d'Etat, B.; Wilhelm, R. A.; Buljan, M.; Siketi?, Z.; Scholz, F.; Meisch, T.; Jakši?, M.; Bernstorff, S.; Schleberger, M.; Šanti?, B.

    2015-08-01

    We investigated the response of wurzite GaN thin films to energetic ion irradiation. Both swift heavy ions (92?MeV Xe23+, 23?MeV I6+) and highly charged ions (100?keV Xe40+) were used. After irradiation, the samples were investigated using atomic force microscopy, grazing incidence small angle x-ray scattering, Rutherford backscattering spectroscopy in channelling orientation and time of flight elastic recoil detection analysis. Only grazing incidence swift heavy ion irradiation induced changes on the surface of the GaN, when the appearance of nanoholes is accompanied by a notable loss of nitrogen. The results are discussed in the framework of the thermal spike model.

  14. Influence of Xe{sub 2}{sup +} ions on the micro-hollow cathode discharge driven by thermionic emission

    SciTech Connect

    Levko, D.; Bliokh, Y. P.; Krasik, Ya. E.

    2014-04-15

    The influence of Xe{sub 2}{sup +} dimer ions and excited Xe* atoms on the hollow cathode discharge driven by electron thermionic emission is studied using two-dimensional Particle-in-Cell Monte Carlo Collisions modeling. A comparison with the results of two-component (electrons and Xe{sup +} ions) plasma modeling showed that the presence of the Xe{sub 2}{sup +} dimer ions and excited Xe* atoms in the plasma affects the plasma parameters (density, potential, and ion fluxes toward the cathode). The influence of Xe{sub 2}{sup +} ions and Xe* atoms on the plasma sheath parameters, such as thickness and the ion velocity at the sheath edge, is analyzed.

  15. Observation of hyperfine mixing in measurements of a magnetic octupole decay in isotopically pure nickel-like 129Xe and 132Xe ions

    SciTech Connect

    Trabert, E; Beiersdorfer, P; Brown, G V

    2006-12-21

    We present measurements of high statistical significance of the rate of the magnetic octupole (M3) decay in nickel-like ions of isotopically pure {sup 129}Xe and {sup 132}Xe. On {sup 132}Xe, an isotope with zero nuclear spin and therefore without hyperfine structure, the lifetime of the metastable level was established as (15.06 {+-} 0.24) ms. On {sup 129}Xe, an additional fast (2.7 {+-} 0.1 ms) decay component was established that represents hyperfine mixing with a level that decays by electric quadrupole (E2) radiation.

  16. Track lengths of energetic 132Xe ions in CR-39 detectors

    NASA Astrophysics Data System (ADS)

    Ghosh, S.; Raju, J.; Dwivedi, K. K.

    1994-06-01

    Studies of particle tracks in solids have wide ranging applications in many diverse fields of science and technology. Most of these studies require a precise knowledge of heavy ion track lengths or ranges in various knowledge of heavy ion track lengths or ranges in various commonly used solid dielectrics. We have measured the maximum etchable track lengths of 132Xe at 12 different energies ranging from 5.8 MeV/u to 17.0 MeV/u in CR-39 (Homalite). The ion beam with an initial energy of 17.0 MeV/u was degraded by aluminium foils of different thickness. The detectors were irradiated at an angle of 45° to the beam direction and were etched for a period of 2?6 hrs in 6N NaOH at 55°C to reveal the tracks. The track lengths were measured using an optical microscope and the maximum etchable track lengths were determined. The standard deviations have been evaluated and the experimental results are compared with theoretical values obtained from computer codes ?RANGE? and ?TRIM? and the program of Henke and Benton.

  17. Radiolysis and sputtering of carbon dioxide ice induced by swift Ti, Ni, and Xe ions

    NASA Astrophysics Data System (ADS)

    Mejía, C.; Bender, M.; Severin, D.; Trautmann, C.; Boduch, Ph.; Bordalo, V.; Domaracka, A.; Lv, X. Y.; Martinez, R.; Rothard, H.

    2015-12-01

    Solid carbon dioxide (CO2) is found in several bodies of the solar system, the interstellar medium (ISM) and young stellar objects, where it is exposed to cosmic and stellar wind radiation. Here, the chemical and physical modifications induced by heavy ion irradiation of pure solid CO2 at low temperature (T = 15-30 K) are analyzed. The experiments were performed with Ti (550 MeV) and Xe (630 MeV) ions at the UNILAC of GSI/Darmstadt and with Ni ions (46 and 52 MeV) at IRRSUD of GANIL/Caen. The evolution of the thin CO2 ice films (deposited on a CsI window) was monitored by mid-infrared absorption spectroscopy (FTIR). The dissociation rate of CO2, determined from the fluence dependence of the IR absorption peak intensity, is found to be proportional to the electronic stopping power Se. We also confirm that the sputtering yield shows a quadric increase with electronic stopping power. Furthermore, the production rates of daughter molecules such as CO, CO3 and O3 were found to be linear in Se.

  18. Optima XE Single Wafer High Energy Ion Implanter

    SciTech Connect

    Satoh, Shu; Ferrara, Joseph; Bell, Edward; Patel, Shital; Sieradzki, Manny

    2008-11-03

    The Optima XE is the first production worthy single wafer high energy implanter. The new system combines a state-of-art single wafer endstation capable of throughputs in excess of 400 wafers/hour with a production-proven RF linear accelerator technology. Axcelis has been evolving and refining RF Linac technology since the introduction of the NV1000 in 1986. The Optima XE provides production worthy beam currents up to energies of 1.2 MeV for P{sup +}, 2.9 MeV for P{sup ++}, and 1.5 MeV for B{sup +}. Energies as low as 10 keV and tilt angles as high as 45 degrees are also available., allowing the implanter to be used for a wide variety of traditional medium current implants to ensure high equipment utilization. The single wafer endstation provides precise implant angle control across wafer and wafer to wafer. In addition, Optima XE's unique dose control system allows compensation of photoresist outgassing effects without relying on traditional pressure-based methods. We describe the specific features, angle control and dosimetry of the Optima XE and their applications in addressing the ever-tightening demands for more precise process controls and higher productivity.

  19. Ion-ion neutralization of iodine in radio-frequency inductive discharges of Xe and I2 mixtures

    E-print Network

    Kushner, Mark

    Ion-ion neutralization of iodine in radio-frequency inductive discharges of Xe and I2 mixtures Paul. We found that in time modulated discharges, the emissions from excited states of atomic iodine decays sources using a xenon/iodine gas mixture are being investigated as a multiwavelength UV lighting source

  20. Simultaneous imaging electron- and ion-feature Thomson scattering measurements of radiatively heated Xe

    SciTech Connect

    Pollock, B. B.; Meinecke, J.; Kuschel, S.; Ross, J. S.; Divol, L.; Glenzer, S. H.; Shaw, J. L.; Stoafer, C.; Tynan, G. R.

    2012-10-15

    Uniform density and temperature Xe plasmas have been produced over >4 mm scale-lengths using x-rays generated in a cylindrical Pb cavity. The cavity is 750 {mu}m in depth and diameter, and is heated by a 300 J, 2 ns square, 1054 nm laser pulse focused to a spot size of 200 {mu}m at the cavity entrance. The plasma is characterized by simultaneous imaging Thomson scattering measurements from both the electron and ion scattering features. The electron feature measurement determines the spatial electron density and temperature profile, and using these parameters as constraints in the ion feature analysis allows an accurate determination of the charge state of the Xe ions. The Thomson scattering probe beam is 40 J, 200 ps, and 527 nm, and is focused to a 100 {mu}m spot size at the entrance of the Pb cavity. Each system has a spatial resolution of 25 {mu}m, a temporal resolution of 200 ps (as determined by the probe duration), and a spectral resolution of 2 nm for the electron feature system and 0.025 nm for the ion feature system. The experiment is performed in a Xe filled target chamber at a neutral pressure of 3-10 Torr, and the x-rays produced in the Pb ionize and heat the Xe to a charge state of 20{+-}4 at up to 200 eV electron temperatures.

  1. On the preparation of fluorine-18 labelled XeF(2) and chemical exchange between fluoride ion and XeF(2).

    PubMed

    Vasdev, Neil; Pointner, Bernard E; Chirakal, Raman; Schrobilgen, Gary J

    2002-10-30

    A recent report claims to have prepared [18F]XeF2 by exchange between a large stoichiometric excess of XeF2 and no-carrier-added 18F-, as salts of the [2,2,2-crypt-M+] (M = K or Cs) cations, in CH2Cl2 or CHCl3 solvents at room temperature. Attempts to repeat this work have proven unsuccessful and have led to a critical reinvestigation of chemical exchange between fluoride ion, in the form of anhydrous [N(CH3)4][F] and [2,2,2-crypt-K][F], and XeF2 in dry CH2Cl2 and CH3CN solvents. It was shown, by use of 19F and 1H NMR spectroscopies, that [2,2,2-crypt-K][F] rapidly reacts with CH3CN solvent to form HF2-, and with CH2Cl2 solvent to form HF2-, CH2ClF, and CH2F2 at room temperature. Moreover, XeF2 rapidly oxidizes 2,2,2-crypt in CH2Cl2 solvent at room temperature to form HF and HF2-. Thus, the exchange between XeF2 and no-carrier-added 18F- reported in the prior work arises from exchange between XeF2 and HF/HF2-, and does not involve fluoride ion. However, naked fluoride ion has been shown to undergo exchange with XeF2 under rigorously anhydrous and HF-free conditions. A two-dimensional 19F-19F EXSY NMR study demonstrated that [N(CH3)4][F] exchanges with XeF2 in CH3CN solvent, but exchange of HF2- with either XeF2 or F- is not detectable under these conditions. The exchange between XeF2 and F- is postulated to proceed by the formation of XeF3- as the exchange intermediate. PMID:12392433

  2. An attempt to reproduce high burn-up structure by ion irradiation of SIMFUEL

    NASA Astrophysics Data System (ADS)

    Baranov, V. G.; Lunev, A. V.; Reutov, V. F.; Tenishev, A. V.; Isaenkova, M. G.; Khlunov, A. V.

    2014-09-01

    Experiments in IC-100 and U-400 cyclotrons were conducted with SIMFUEL pellets (11.47 wt.% of fission products simulators) to reproduce some aspects of the long-term irradiation conditions in epithermal reactors. Pellets were irradiated with Xe16+, Xe24+ and He+ at energies ranging from 20 keV (He+) to 320 keV (Xe16+) and 1-90 MeV (Xe24+). Some samples were subsequently annealed to obtain larger grain sizes and to study defects recovery. The major microstructural changes consisted in grain sub-division observed on SEM and AFM images and change in composition registered by EPMA (pellets irradiated with 1-90 MeV Xe24+ ions at fluence of 5 × 1015 cm-2). Lattice distortion and increase in dislocation density is also noted according to X-ray data. At low energies and high fluences formation of bubbles (20 keV He+ at 5.5 × 1017 cm-2) was observed. Grain sub-division exhibits full coverage of the grain body and preservation of former grain boundaries. The size of sub-grains depends on local dislocation density and changes from 200 nm to 400 nm along the irradiated surface. Beneath it the size ranges from 150 to 600 nm. Sub-grains are not observed in samples irradiated by low-energy ions even at high dislocation densities.

  3. Ion-Pair XeO Emission from a Microwave Discharge

    NASA Astrophysics Data System (ADS)

    Cekic, M.; Frank, J.; Popovic, S.

    1998-10-01

    Molecular structure of the low lying excited states of XeO was studied in more detail in relation of excimer lasers. Rare gas halide excimer lasers established themselves as more efficient ultraviolet sources, and the remaining problems related with molecular structure of XeO were set aside and forgotten. Hence very little information is still available about ion pair and Rydberg states of XeO. Apart of a vague statement about an extended continuum, peaking at 237 nm, and a tentative assignment for a dozen of ion pair states, little is known about their complex structure. In our continuing search for high-intensity, narrow-band ultraviolet light sources as candidates for substituting high intensity mercury lamps in various applications, we performed experiments with high pressure, microwave-excited mixtures of Xe with O2 and N_2O. Dominant feature in the spectrum is the 237-nm band extending probably rather deep below 200 nm with the characteristic narrow peak near the band's head. Width of the band indicates a very deep potential energy minimum with many vibrational levels, characteristic for the ion-pair upper excited state. Contrary to the previous description of the band, there is a visible structure, showing a probable overlap of two or more different states.

  4. Measurement of a magnetic-dipole transition probability in Xe32+ using an electron-beam ion trap 

    E-print Network

    Serpa, F. G.; Morgan, C. A.; Meyer, E. S.; Gillaspy, J. D.; Trabert, E.; Church, David A.; Takacs, E.

    1997-01-01

    The transition probability for the 3d(4) D-5(2) <-- D-5(3) magnetic-dipole transition in Ti-like Xe (Xe32+) has been measured using an electron-beam ion trap. The unusually weak dependence of the transition energy on nuclear charge Z, and the fact...

  5. Ion-irradiation effect on high-temperature behaviors of advanced SiC fibers

    NASA Astrophysics Data System (ADS)

    Shimoda, K.; Colin, C.; Kishimoto, H.; Doriota, S.

    2011-10-01

    Heavy ion beam irradiation is usually chosen to simulate neutron irradiation damages in materials. However, there has the difficulty to study macro-properties of irradiated materials due to the very small affected depth. In this study, we have explored macro-properties of the ion-irradiated materials, owing to very fine diameter of Tyranno™-SA SiC fibers. The fibers were irradiated at a National Large Accelerator of Heavy Ions facility, GANIL (Caen, France), under 95 MeV Xe ions at room-temperature. To prevent the damage gradient in fiber, the fibers were irradiated on two sides with two fluence levels. According to TRIM-code calculation, the irradiation damages in the fibers affected the entire volume of the fibers with estimations of 0.05 and 0.2 dpa. The high-temperature behaviors of the ion-irradiated fibers from room temperature to 1200 °C were investigated by a specific tensile test device of single fiber, named MacaSiC. The thermo-elastic modulus of the ion-irradiated fibers showed the recovering, which started from 600 °C during heating. The thermo-electrical conductivity of the ion-irradiated fibers gradually increased until 900 °C and then saturated during heating and gradually decreased during cooling. The normalized value of electrical conductivity for 0.05 dpa irradiated fibers had higher than that of 0.02 dpa irradiated fibers after heating and cooling.

  6. Ion-ion neutralization of iodine in radio-frequency inductive discharges of Xe and I{sub 2} mixtures

    SciTech Connect

    Barnes, P.N.; Kushner, M.J.

    1997-09-01

    Xe/I{sub 2} low-pressure electric discharges are being developed as efficient, long-lived ultraviolet lighting sources. In this work the kinetics of low pressure, 0.5{endash}5 Torr, radio-frequency inductively excited discharges sustained in Xe and I{sub 2} were investigated to determine the source of radiating states. The diagnostics applied in this study include optical absorption and emission spectroscopy, microwave interferometry, and microwave absorption. We found that in time modulated discharges, the emissions from excited states of atomic iodine decays with time constants of hundreds of microseconds. These observations are consistent with those states being populated by ion-ion neutralization. Electron-ion recombination leading to excited states appears not to be an important source of emission.

  7. Photoionization cross section calculations for the halogen-like ions Kr$^+$ and Xe$^+$

    E-print Network

    McLaughlin, B M

    2012-01-01

    Photoionization cross sections calculations on the halogen-like ions; Kr$^+$ and Xe$^+$ have been performed for a photon energy range from each ion threshold to 15 eV, using large-scale close-coupling calculations within the Dirac-Coulomb R-matrix approximation. The results from our theoretical work are compared with recent measurements made at the ASTRID merged-beam set-up at the University of Aarhus in Denmark and from the Fourier transform ion cyclotron resonance (FT-ICR) trap method at the SOLEIL synchrotron radiation facility in Saint-Aubin, France and the Advanced Light Soure (ALS). For each of these complex ions our theoretical cross section results over the photon energy range investigated are seen to be in excellent agreement with experiment. Resonance energy positions and quantum defects of the prominent Rydberg resonances series identified in the spectra are compared with experiment for these complex halogen like-ions.

  8. 1 MeV electron irradiation of solid Xe nanoclusters in Al : an in-situ HRTEM study.

    SciTech Connect

    Donnelly, S. E.; Furuya, K.; Song, M.; Birtcher, R. C.; Allen, C. W.

    1997-12-05

    Thin film samples of a simple embedded nanocluster system consisting of solid Xe precipitates in Al have been subjected to 1 MeV electron irradiation in a high-voltage electron microscope. High-resolution images have been recorded on videotape in order to monitor the changes to the system resulting from the passage of electrons through the film. Inspection of the video recordings (in some cases frame-by-frame) reveals that complex, rapid processes occur under the electron beam. These include, movement of small clusters, coalescence of neighboring clusters, shape changes, the apparent melting and resolidification of the Xe, and the creation and annealing of extended defects within the Xe lattice. A tentative interpretation of some of the observations is presented in terms of the electron-induced displacement processes at the surface of the clusters.

  9. Study on ion-irradiation-induced ferromagnetism in FeRh intermetallic compound by means of magnetic Compton scattering

    SciTech Connect

    Kosugi, S.; Matsui, T.; Aikoh, K.; Shimizu, K.; Tahara, Y.; Hori, F.; Iwase, A.; Ishikawa, N.; Itou, M.; Sakurai, Y.

    2011-04-01

    The magnetic Compton profiles of Fe-50 at. % Rh intermetallic compound were measured to study the ferromagnetism induced by 200 MeV Xe ion irradiation. The magnetic effect at 50 K increases with increasing the ion-fluence. The analysis of the experimental result revealed that the values of spin moment induced by the irradiation were close to the values of magnetization obtained by a superconducting quantum interference device magnetometer, suggesting that the ion irradiation mainly induces the spin magnetic moment. The difference in magnetic Compton profiles between the irradiation-induced ferromagnetism and the intrinsic ferromagnetism in pure Fe is also discussed.

  10. XeF4 as a ligand for a metal ion.

    PubMed

    Tavcar, Gasper; Zemva, Boris

    2009-01-01

    Noble molecule: [Mg(XeF(2))(XeF(4))](AsF(6))(2) is the first coordination compound in which XeF(4) acts as a ligand to a metal center. It is also the first known compound, in which XeF(2) and XeF(4) are simultaneously coordinated to the same metal center (see structure; purple Xe, green F, gray Mg, yellow As). PMID:19140146

  11. Zn nanoparticles irradiated with swift heavy ions at low fluences: Optically-detected shape elongation induced by nonoverlapping ion tracks

    SciTech Connect

    Amekura, H.; Mitsuishi, K.; Nakayama, Y.; Kishimoto, N.; Ishikawa, N.; Okubo, N.; Ridgway, M. C.; Giulian, R.; Buchal, Ch.; Mantl, S.

    2011-05-15

    Elongation of metal nanoparticles (NPs) embedded in silica (SiO{sub 2}) induced by swift heavy-ion (SHI) irradiation, from spheres to spheroids, has been evaluated mainly by transmission electron microscopy (TEM) at high fluences, where tens to thousands of ion tracks were overlapped each other. It is important to clarify whether the high fluences, i.e., track overlaps, are essential for the elongation. In this study the elongation of metal NPs was evaluated at low fluences by linearly polarized optical absorption spectroscopy. Zn NPs embedded in silica were irradiated with 200-MeV Xe{sup 14+} ions with an incident angle of 45 deg. The fluence ranged from 1.0x10{sup 11} to 5.0x10{sup 13} Xe/cm{sup 2}, which corresponds to the track coverage ratio (CR) of 0.050 to 25 by ion tracks. A small but certain dichroism was observed down to 5.0x10{sup 11} Xe/cm{sup 2} (CR = 0.25). The comparison with numerical simulation suggested that the elongation of Zn NPs was induced by nonoverlapping ion tracks. After further irradiation each NP experienced multiple SHI impacts, which resulted in further elongation. TEM observation showed the elongated NPs whose aspect ratio (AR) ranged from 1.2 to 1.7 at 5.0x10{sup 13} Xe/cm{sup 2}. Under almost the same irradiation conditions, Co NPs with the same initial mean radius showed more prominent elongation with AR of {approx}4 at the same fluence, while the melting point (m.p.) of Co is much higher than that of Zn. Less efficient elongation of Zn NPs while lower m.p. is discussed.

  12. Fast luminescence in vacuum ultraviolet region in heavy-ion-irradiated ?-Al2O3

    NASA Astrophysics Data System (ADS)

    Koshimizu, Masanori; Kimura, Kazuie; Fujimoto, Yutaka; Asai, Keisuke

    2015-12-01

    We analyzed the time-resolved luminescence properties of ?-Al2O3 under heavy ion irradiations in the vacuum ultraviolet (VUV) wavelength region. A luminescence band at approximately 170 nm, at which a luminescence band was observed under VUV irradiation and was ascribed to self-shrunk excitons. The decay rate increased with the linear energy transfer (LET). The luminescence efficiency of the band increased sharply with the LET for the case of Xe irradiation, whose LET was estimated to be higher than the threshold LET for track formation. The fast decay rate and high luminescence intensity for Xe irradiation was explained according to the enhanced radiative rate caused by close interactions among excited states.

  13. A guided-ion beam study of the reactions of Xe{sup +} and Xe{sup 2+} with NH{sub 3} at hyperthermal collision energies

    SciTech Connect

    Levandier, Dale J.; Chiu, Yu-Hui

    2010-10-21

    We have measured the absolute cross sections for reactions of Xe{sup +} and Xe{sup 2+} with NH{sub 3} at collision energies in the range from near-thermal to {approx}34 and {approx}69 eV, respectively. For Xe{sup +}, the cross section for charge transfer, the only exothermic channel, decreases from {approx}200 A{sup 2} below 0.1 eV to {approx}12 A{sup 2} at the highest energies studied. The production of NH{sub 3}{sup +} is the only channel observed below 5 eV, above which a small amount of NH{sub 2}{sup +} is also formed. In Xe{sup 2+} reactions, the main products observed are NH{sub 3}{sup +} and NH{sub 2}{sup +}. The charge transfer cross section decreases monotonically from {approx}80 to {approx}6 A{sup 2} over the studied energy range. The NH{sub 2}{sup +} cross section is similar to the charge transfer cross section at the lowest energies, and exhibits a second component above 0.4 eV, with a maximum of 65 A{sup 2} at 0.7 eV, above which the cross section decreases to {approx}30 A{sup 2} at the highest energies studied. At energies above 10 eV, a small amount of NH{sup +} is also observed in Xe{sup 2+} collisions. Product recoil velocity distributions were determined at selected collision energies, using guided-ion beam time-of-flight methods.

  14. Dose Control System in the Optima XE Single Wafer High Energy Ion Implanter

    SciTech Connect

    Satoh, Shu; Yoon, Jongyoon; David, Jonathan

    2011-01-07

    Photoresist outgassing can significantly compromise accurate dosimetry of high energy implants. High energy implant even at a modest beam current produces high beam powers which create significantly worse outgassing than low and medium energy implants and the outgassing continues throughout the implant due to the low dose in typical high energy implant recipes. In the previous generation of high energy implanters, dose correction by monitoring of process chamber pressure during photoresist outgassing has been used. However, as applications diversify and requirements change, the need arises for a more versatile photoresist correction system to match the versatility of a single wafer high energy ion implanter. We have successfully developed a new dosimetry system for the Optima XE single wafer high energy ion implanter which does not require any form of compensation due to the implant conditions. This paper describes the principles and performance of this new dose system.

  15. Relativistic Many-body Moller-Plesset Perturbation Theory Calculations of the Energy Levels and Transition Probabilities in Na- to P-like Xe Ions

    SciTech Connect

    Vilkas, M J; Ishikawa, Y; Trabert, E

    2007-03-27

    Relativistic multireference many-body perturbation theory calculations have been performed on Xe{sup 43+}-Xe{sup 39+} ions, resulting in energy levels, electric dipole transition probabilities, and level lifetimes. The second-order many-body perturbation theory calculation of energy levels included mass shifts, frequency-dependent Breit correction and Lamb shifts. The calculated transition energies and E1 transition rates are used to present synthetic spectra in the extreme ultraviolet range for some of the Xe ions.

  16. Ion charge-resolved branching in decay of inner shell holes in Xe up to 1200 eV

    NASA Astrophysics Data System (ADS)

    Eland, J. H. D.; Slater, C.; Zagorodskikh, S.; Singh, R.; Andersson, J.; Hult-Roos, A.; Lauer, A.; Squibb, R. J.; Feifel, R.

    2015-10-01

    Using a new multi-electron multi-ion coincidence apparatus and soft x-ray synchrotron radiation we have determined branching ratios to final Xe n+ states with 2 < n < 9 from the 4d-1, 4p-1, 4s-1, 3d-1 and 3p-1 Xe+ hole states. The coincident electron spectra give information on the Auger cascade pathways. We show that by judicious choice of coincident electrons, almost pure single charge states of the final ions can be selected.

  17. Tracing electron-ion recombination in nanoplasmas produced by extreme-ultraviolet irradiation of rare-gas clusters.

    PubMed

    Schütte, B; Campi, F; Arbeiter, M; Fennel, Th; Vrakking, M J J; Rouzée, A

    2014-06-27

    We investigate electron-ion recombination in nanoplasmas produced by the ionization of rare-gas clusters with intense femtosecond extreme-ultraviolet (XUV) pulses. The relaxation dynamics following XUV irradiation is studied using time-delayed 790-nm pulses, revealing the generation of a large number of excited atoms resulting from electron-ion recombination. In medium-sized Ar-Xe clusters, these atoms are preferentially created in the Xe core within 10 ps after the cluster ionization. The ionization of excited atoms serves as a sensitive probe for monitoring the cluster expansion dynamics up to the ns time scale. PMID:25014813

  18. Production of highly charged ion beams Kr32+, Xe44+, Au54+ with Electron String Ion Source (ESIS) Krion-2 and corresponding basic and applied studies

    NASA Astrophysics Data System (ADS)

    Donets, D. E.; Donets, E. D.; Donets, E. E.; Salnikov, V. V.; Shutov, V. B.

    2010-09-01

    Electron String Ion Source (ESIS) Krion-2 (JINR, Dubna) was used for basic and applied research in various aspects of multiply charged heavy ions production. Energy recuperation mode in ESIS has been proofed first and used for production of highly charged ions 84Kr28+÷84Kr32+, 124Xe40÷124Xe44 and Au51+÷ Au54+. Krion-2 ESIS was mounted on high voltage (HV) platform of LU-20 Linac and used as an injector of highly charged ions during Nuclotron run N° 41. Krion-2 ESIS has produced 3.0.107 124Xe42+ ions per pulse of 7 ?s duration. This ion beam was injected into LU-20 and Nuclotron, accelerated up to energy of 186 GeV and the extracted Xe beam was used for physics experiments. Electron String Ion Source Krion-2 demonstrated the high reliability and stability running during 30 days on HV platform. We believe that it is due to an extremely low electron beam power, provided by using the electron string mode of operation: 50 W pulse power and about 10 W average power. Other possible application of ESIS could be its use in injection complexes of synchrotrons and cyclotrons for cancer therapy. Slow and fast extraction of C4+ and C6+ beams from Krion-2 ESIS were preliminary studied towards ESIS optimization for medical accelerators requirements.

  19. Heavy Ion Irradiated Ferromagnetic Films: The Cases of Cobalt and Iron

    NASA Astrophysics Data System (ADS)

    Lieb, K. P.; Zhang, K.; Müller, G. A.; Gupta, R.; Schaaf, P.

    2005-01-01

    Polycrystalline, e-gun deposited Co, Fe and Co/Fe films, tens of nanometers thick, have been irradiated with Ne, Kr, Xe and/or Fe ions to fluences of up to 5 × 1016 ions/cm2. Changes in the magnetic texture induced by the implanted ions have been measured by means of hyperfine methods, such as Magnetic Orientation Mössbauer Spectroscopy (Fe), and by Magneto-Optical Kerr Effect and Vibrating Sample Magnetometry. In Co and CoFe an hcp ? fcc phase transition has been observed under the influence of Xe-ion implantation. For 1016 Xe-ions/cm2, ion beam mixing in the Co/Fe system produces a soft magnetic material with uniaxial anisotropy. The effects have been correlated with changes in the microstructure as determined via X-ray diffraction. The influences of internal and external strain fields, an external magnetic field and pre-magnetization have been studied. A comprehensive understanding of the various effects and underlying physical reasons for the modifications appears to emerge from these investigations.

  20. Swift heavy ion irradiation of ZnO nanoparticles embedded in silica: Radiation-induced deoxidation and shape elongation

    SciTech Connect

    Amekura, H.; Tsuya, D.; Mitsuishi, K.; Nakayama, Y.; Okubo, N.; Ishikawa, N.; Singh, U. B.; Khan, S. A.; Avasthi, D. K.; Mohapatra, S.

    2013-11-11

    ZnO nanoparticles (NPs) embedded in amorphous SiO{sub 2} were irradiated with 200 MeV Xe{sup 14+} swift heavy ions (SHIs) to a fluence of 5.0 × 10{sup 13} ions/cm{sup 2}. Optical linear dichroism was induced in the samples by the irradiation, indicating shape transformation of the NPs from spheres to anisotropic ones. Transmission electron microscopy observations revealed that some NPs were elongated to prolate shapes; the elongated NPs consisted not of ZnO but of Zn metal. The SHI irradiation induced deoxidation of small ZnO NPs and successive shape elongation of the deoxidized metal NPs.

  1. Xenon-nitrogen chemistry: gas-phase generation and theoretical investigation of the xenon-difluoronitrenium ion F2N-Xe+.

    PubMed

    Operti, Lorenza; Rabezzana, Roberto; Turco, Francesca; Borocci, Stefano; Giordani, Maria; Grandinetti, Felice

    2011-09-12

    The xenon-difluoronitrenium ion F(2)N-Xe(+) , a novel xenon-nitrogen species, was obtained in the gas phase by the nucleophilic displacement of HF from protonated NF(3) by Xe. According to Møller-Plesset (MP2) and CCSD(T) theoretical calculations, the enthalpy and Gibbs energy changes (?H and ?G) of this process are predicted to be -3 kcal mol(-1) . The conceivable alternative formation of the inserted isomers FN-XeF(+) is instead endothermic by approximately 40-60 kcal mol(-1) and is not attainable under the employed ion-trap mass spectrometric conditions. F(2)N-Xe(+) is theoretically characterized as a weak electrostatic complex between NF(2)(+) and Xe, with a Xe-N bond length of 2.4-2.5 Å, and a dissociation enthalpy and free energy into its constituting fragments of 15 and 8 kcal mol(-1), respectively. F(2)N-Xe(+) is more fragile than the xenon-nitrenium ions (FO(2)S)(2)NXe(+), F(5)SN(H)Xe(+), and F(5)TeN(H)Xe(+) observed in the condensed phase, but it is still stable enough to be observed in the gas phase. Other otherwise elusive xenon-nitrogen species could be obtained under these experimental conditions. PMID:21826753

  2. Differential electron emission in the ionization of Ne and Xe atoms under fast bare carbon ion impact

    NASA Astrophysics Data System (ADS)

    Biswas, Shubhadeep; Monti, J. M.; Tachino, C. A.; Rivarola, R. D.; Tribedi, L. C.

    2015-06-01

    Measurement of the energy and angular distributions of the double differential cross section (DDCS) of electron emission from Ne and Xe atoms in collision with 5 MeV u-1 bare carbon ions is reported. This study aimed to investigate the electron emission processes in the case of multi-electronic systems. In general, several clear differences between the electron emission spectra of Ne and Xe are found, which indicate the influence of the increasing number of electrons. For instance, the sharp peak due to the binary nature of collision is almost absent in the case of Xe, unlike Ne, which could be understood due to the increasing contribution from the strongly bound inner shell (such as 4d) electrons for the Xe atom. The forward-backward angular asymmetry has also been derived from the angular distributions. For Xe, the qualitative behaviour of the asymmetry parameter is seen to be quite different since it reveals structures due to Auger contributions. It is, in general, different and much lower than that for Ne, which shows the smooth behaviour that one finds for other lighter atoms like He. The single differential and total cross sections are also derived. The theoretical calculations based on the prior form of the continuum distorted wave-eikonal initial state (CDW-EIS) approximation have been provided for both the targets. Overall, it gives a very good agreement with the energy and the angular distributions of DDCS for Ne. For Xe, the agreement is not as good as for Ne. We also provide a detailed discussion on the DDCS obtained from different sub-shell ionization, estimated in this framework.

  3. Heavy ion irradiation of crystalline water ice

    E-print Network

    Dartois, E; Boduch, P; Brunetto, R; Chabot, M; Domaracka, A; Ding, J J; Kamalou, O; Lv, X Y; Rothard, H; da Silveira, E F; Thomas, J C

    2015-01-01

    Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic ...

  4. In situ ion irradiation of zirconium carbide

    NASA Astrophysics Data System (ADS)

    Ulmer, Christopher J.; Motta, Arthur T.; Kirk, Mark A.

    2015-11-01

    Zirconium carbide (ZrC) is a candidate material for use in one of the layers of TRISO coated fuel particles to be used in the Generation IV high-temperature, gas-cooled reactor, and thus it is necessary to study the effects of radiation damage on its structure. The microstructural evolution of ZrCx under irradiation was studied in situ using the Intermediate Voltage Electron Microscope (IVEM) at Argonne National Laboratory. Samples of nominal stoichiometries ZrC0.8 and ZrC0.9 were irradiated in situ using 1 MeV Kr2+ ions at various irradiation temperatures (T = 20 K-1073 K). In situ experiments made it possible to continuously follow the evolution of the microstructure during irradiation using diffraction contrast imaging. Images and diffraction patterns were systematically recorded at selected dose points. After a threshold dose during irradiations conducted at room temperature and below, black-dot defects were observed which accumulated until saturation. Once created, the defect clusters did not move or get destroyed during irradiation so that at the final dose the low temperature microstructure consisted only of a saturation density of small defect clusters. No long-range migration of the visible defects or dynamic defect creation and elimination were observed during irradiation, but some coarsening of the microstructure with the formation of dislocation loops was observed at higher temperatures. The irradiated microstructure was found to be only weakly dependent on the stoichiometry.

  5. Deformation behavior of ion-irradiated polyimide

    SciTech Connect

    Kucheyev, S.O.; Felter, T.E.; Anthamatten, M.; Bradby, J.E.

    2004-08-02

    We study nanoindentation hardness, Young's modulus, and tensile strength of polyimide (Kapton H) films bombarded with MeV light ions in the predominantly electronic stopping power regime. Results show that, for all the ion irradiation conditions studied, bombardment increases the hardness and Young's modulus and decreases the tensile strength. These changes depend close to linearly on ion fluence and superlinearly (with a power-law exponent factor of {approx}1.5) on electronic energy loss. Physical mechanisms of radiation-induced changes to mechanical properties of polyimide are discussed.

  6. Ion irradiation effects in natural garnets: Comparison with zircon

    E-print Network

    Utsunomiya, Satoshi

    Ion irradiation effects in natural garnets: Comparison with zircon S. Utsunomiya, L.M. Wang, R ; Z ¼ 8) under ion-beam irradiation was investigated in order to compare its radiation susceptibility during the ion irradiation at high temperature. This behavior may be related to the phase relations

  7. Cadmium Nanowire Formation Induced by Ion Irradiation

    SciTech Connect

    Jiang, Weilin; Weber, William J.; Wang, Chong M.; Young, James S.; Boatner, Lynn A.; Lian, Jie; Wang, Lumin; Ewing, Rodney C.

    2005-07-04

    One-dimensional nanostructures, such as nanowires, of semiconductors and metals are of great technological interest due to their potential for many advanced technology applications. Utilization of these materials versus their bulk counterparts will not only allow for device miniaturisation, but also may improve device performance or create new functions. Here we report a novel method for the synthesis of crystalline Cd-nanowires without involving either templates or a “seeded” structure. Ion irradiation at low temperatures (? 295 K) has been used to induce material decomposition and phase segregation in a cadmium niobate pyrochlore (Cd2Nb2O7) wafer. During the formation and rupture of the gas-filled blisters in the material, soft metallic Cd is extruded/extracted as nanowires through pores in the exfoliated layer. The entire process may be readily controlled by changing the ion irradiation conditions (e.g., ion species, dose and energy) with minimal thermal constraints.

  8. Mutation induced with ion beam irradiation in rose

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Nagatomi, S.; Morishita, T.; Degi, K.; Tanaka, A.; Shikazono, N.; Hase, Y.

    2003-05-01

    The effects of mutation induction by ion beam irradiation on axillary buds in rose were investigated. Axillary buds were irradiated with carbon and helium ion beams, and the solid mutants emerged after irradiation by repeated cutting back. In helium ion irradiation, mutations were observed in plants derived from 9 buds among 56 irradiated buds in 'Orange Rosamini' and in plants derived from 10 buds among 61 irradiated buds in 'Red Minimo'. In carbon ion, mutations were observed in plants derived from 12 buds among 88 irradiated buds in 'Orange Rosamini'. Mutations were induced not only in higher doses but also in lower doses, with which physiological effect by irradiation was hardly observed. Irradiation with both ion beams induced mutants in the number of petals, in flower size, in flower shape and in flower color in each cultivar.

  9. Irradiation of nuclear track emulsions with thermal neutrons, heavy ions, and muons

    NASA Astrophysics Data System (ADS)

    Artemenkov, D. A.; Bradnova, V.; Zaitsev, A. A.; Zarubin, P. I.; Zarubina, I. G.; Kattabekov, R. R.; Mamatkulov, K. Z.; Rusakova, V. V.

    2015-07-01

    Exposures of test samples of nuclear track emulsion were analyzed. Angular and energy correlations of products originating from the thermal-neutron-induced reaction n th +10 B ? 7 Li + (?)+ ? were studied in nuclear track emulsions enriched in boron. Nuclear track emulsions were also irradiated with 86Kr+17 and 124Xe+26 ions of energy about 1.2 MeV per nucleon. Measurements of ranges of heavy ions in nuclear track emulsionsmade it possible to determine their energies on the basis of the SRIM model. The formation of high-multiplicity nuclear stars was observed upon irradiating nuclear track emulsions with ultrarelativistic muons. Kinematical features studied in this exposure of nuclear track emulsions for events of the muon-induced splitting of carbon nuclei to three alpha particles are indicative of the nucleardiffraction interaction mechanism.

  10. Chromosomal instability induced by heavy ion irradiation

    NASA Technical Reports Server (NTRS)

    Limoli, C. L.; Ponnaiya, B.; Corcoran, J. J.; Giedzinski, E.; Morgan, W. F.

    2000-01-01

    PURPOSE: To establish the dose-response relationship for the induction of chromosomal instability in GM10115 cells exposed to high-energy iron ions (1 GeV/nucleon, mean LET 146 keV/microm) and gold ions (11 GeV/nucleon, mean LET 1450 keV/microm). Past work has established that sparsely ionizing X-rays can induce a long-lived destabilization of chromosomes in a dose-dependent manner at an incidence of approximately 3% per gray. The present investigation assesses the capacity of High-Z and High-energy (HZE) particles to elicit this same endpoint. MATERIALS AND METHODS: Clonal populations derived from single progenitor cells surviving heavy-ion irradiation were analyzed cytogenetically to identify those clones showing a persistent destablization of chromosomes. RESULTS: Dose-response data, with a particular emphasis at low dose (< 1.0 Gy), indicate a frequency of approximately 4% per gray for the induction of chromosomal instability in clones derived from single progenitor cells surviving exposure to iron ions. The induction of chromosomal instability by gold ions was, however, less responsive to applied dose, as the observed incidence of this phenotype varied from 0 to 10% over 1-8 Gy. Both iron and gold ions gave dose-dependent increases in the yield of chromosomal aberrations (both chromosome- and chromatid-type) measured at the first mitosis following irradiation, as well as shoulderless survival curves having D0=0.87 and 1.1 Gy respectively. CONCLUSIONS: Based on the present dose-response data, the relative biological effectiveness of iron ions is 1.3 for the induction of chromosomal instability, and this indicates that heavy ions are only slightly more efficient than X-rays at eliciting this delayed phenotype.

  11. Surface and interface modification of Zr/SiC interface by swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Njoroge, E. G.; Theron, C. C.; Malherbe, J. B.; van der Berg, N. G.; Hlatshwayo, T. T.; Skuratov, V. A.

    2015-07-01

    In this study thin Zr films (135 nm) were deposited on 6H-SiC substrate at room temperature by sputter deposition. The Zr/SiC couples were irradiated by 167 MeV Xe26+ ions at room temperature at fluences of 5.0 × 1012, 1.0 × 1013, 5.0 × 1013, 2.0 × 1014, 3.1 × 1014 and 6.3 × 1014 ions/cm2. The samples were analysed before and after irradiation using Rutherford backscattering spectroscopy (RBS), atomic force microscopy (AFM) and secondary electron microscopy (SEM). The surface morphology from SEM analysis revealed a homogeneous Zr surface which did not vary with increasing fluences of irradiation. AFM analysis revealed that the Rrms surface roughness did increase from the as-deposited value of 1.6 nm and then decrease at higher SHI irradiation fluences to 1.4 nm. RBS results indicate that interface mixing between Zr and SiC interface occurred and varied linearly with irradiation ion fluence. The value obtained for diffusivity of Zr shows that the mixing was due to interdiffusion across the interface during a transient melt phase according to the thermal spike model.

  12. A laser spectroscopic study on Xe+ ion transport phenomena in the E×B discharge of a Hall effect thruster

    NASA Astrophysics Data System (ADS)

    Mazouffre, S.; Gawron, D.; Kulaev, V.; Luna, J. Pérez; Sadeghi, N.

    2008-03-01

    The Velocity Distribution Function (VDF) of metastable Xe+ ions was measured along the channel axis of the 5 kW-class PPS®X000 Hall effect thruster by means of Laser Induced Fluorescence spectroscopy at 834.72 nm for various voltages, magnetic fields and mass flow rates. Axial velocity and dispersion profiles are compared to on-axis profiles obtained with the 1.5 kW-class PPS100 thruster. Outcomes of the comparison are threefold. (i) The broadening of the FDV across the region of strong magnetic field is a general feature for Hall thrusters. It originates in the overlap between ionization and acceleration layers. The velocity dispersion increases with the discharge voltage; it reaches up to 200 eV in unit of kinetic energy at 700 V. (ii) Most of the acceleration potential (?70%) is localized outside the thruster channel whatever the thruster size and operating conditions. The electric field moves upstream when the applied voltage is ramped up; in other words the fraction of potential inside the channel increases with the voltage; (iii) A non negligible amount of very slow and very fast (kinetic energy higher than the applied potential) Xe+ ions are always observed. Such ions may find their origin in space and temporal oscillations of the electric field as suggested by numerical simulations carried out with a hybrid model.

  13. Fabrication of micro/nano-structures using focused ion beam implantation and XeF2 gas-assisted etching

    NASA Astrophysics Data System (ADS)

    Xu, Z. W.; Fang, F. Z.; Fu, Y. Q.; Zhang, S. J.; Han, T.; Li, J. M.

    2009-05-01

    A micro/nano-structure fabrication method is developed using focused ion beam implantation (FIBI) and FIB XeF2 gas-assisted etching (FIB-GAE). Firstly, the FIB parameters' influence on the FIBI depth is studied by SEM observation of the FIBI cross-section cutting by FIB. Nanoparticles with 10-15 nm diameter are found to be evenly distributed in the FIBI layer, which can serve as a XeF2-assisted etching mask when the ion dose is larger than 1.4 × 1017 ions cm-2. The FIBI layers being used as the etching mask for the subsequent FIB-GAE process are explored to create different micro/nano-structures such as nano-gratings, nano-electrode and sinusoidal microstructures. It is found that the method of combining FIBI with subsequent FIB-GAE is efficient and flexible in micro/nano-structuring, and it can effectively remove the redeposition effect compared with the FIB milling method.

  14. Observation of sputtering of yttrium from Y2O3 ceramics by low-energy Ar, Kr, and Xe ion bombardment in microwave-excited plasma

    NASA Astrophysics Data System (ADS)

    Goto, Tetsuya; Sugawa, Shigetoshi

    2015-12-01

    Y2O3 ceramics were immersed in microwave-excited Ar, Kr, and Xe plasmas, and the sputtering of yttrium atoms from Y2O3 ceramics as a result of low-energy (range of approximately 10 eV) Ar, Kr, and Xe ion bombardment was observed. The amount of sputtered yttrium atoms well correlated with the ion bombardment energy estimated by Langmuir probe measurement. The estimated sputtering yield was 10?5 or less for such a low ion bombardment condition.

  15. Irradiation effect of yttria-stabilized zirconia by high dose dual ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Wen; Wang, Xu; Liu, Shi-Yi; Tang, Mei-Xiong; Zhao, Zi-Qiang; Zhang, Peng; Wang, Bao-Yi; Cao, Xing-Zhong

    2014-06-01

    Yttria-stabilized zirconia (YSZ) is irradiated with 2.0-MeV Au2+ ions and 30-keV He+ ions. Three types of He, Au, Au + He (successively) ion irradiation are performed. The maximum damage level of a sequential dual ion beam implanted sample is smaller than single Au ion implanted sample. A comparable volume swelling is found in a sequential dual ion beam irradiated sample and it is also found in a single Au ion implanted sample. Both effects can be explained by the partial reorganization of the dislocation network into weakly damaged regions in the dual ion beam implanted YSZ. A vacancy-assisted helium trapping/diffusion mechanism in the dual ion beam irradiated condition is discussed. No phase transformation or amorphization behavior happens in all types of ion irradiated YSZ.

  16. On-line Raman spectroscopy of calcite and malachite during irradiation with swift heavy ions

    NASA Astrophysics Data System (ADS)

    Dedera, Sebastian; Burchard, Michael; Glasmacher, Ulrich A.; Schöppner, Nicole; Trautmann, Christina; Severin, Daniel; Romanenko, Anton; Hubert, Christian

    2015-12-01

    A new on-line Raman System, which was installed at the M3-beamline at the UNILAC, GSI Helmholtzzentrum für Schwerionenforschung Darmstadt was used for first "in situ" spectroscopic measurements. Calcite and malachite samples were irradiated in steps between 1 × 109 and 1 × 1012 ions/cm2 with Au ions (calcite) and Xe ions (malachite) at an energy of 4.8 MeV/u. After irradiation, calcite revealed a new Raman band at 437 cm-1 and change of the full width at half maximum for the 1087 cm-1 Raman band. The Raman bands of malachite change significantly with increasing fluence. Up to a fluence of 7 × 1010 ions/cm2, all existing bands decrease in intensity. Between 8 × 1010 and 1 × 1011 ions/cm2 a broad Cu2O band between 110 and 220 cm-1 occurs, which superimposes the pre-existing Raman bands. Additionally, a new broad band between 1000 and 1750 cm-1 is formed, which is interpreted as a carbon coating. In contrast to the Cu2O band, the carbon band vanished when further irradiating the sample. The installations as well as first in situ measurements at room temperature are presented.

  17. Local brain heavy ion irradiation induced Immunosuppression

    NASA Astrophysics Data System (ADS)

    Lei, Runhong; Deng, Yulin; Huiyang Zhu, Bitlife.; Zhao, Tuo; Wang, Hailong; Yu, Yingqi; Ma, Hong; Wang, Xiao; Zhuang, Fengyuan; Qing, Hong

    Purpose: To investigate the long term effect of acute local brain heavy ion irradiation on the peripheral immune system in rat model. Methodology: Only the brain of adult male Wistar rats were radiated by heavy ions at the dose of 15 Gy. One, two and three months after irradiation, thymus and spleen were analyzed by four ways. Tunel assay was performed to evaluate the percentage of apoptotic cells in thymus and spleen, level of Inflammatory cytokines (IL-2, IL-6, SSAO, and TNF-?) was detected by ELISA assay, the differentiation of thymus T lymphocyte subsets were measured by flow cytometry and the relative expression levels of genes related to thymus immune cell development were measured by using quantitative real-time PCR. Results: Thymus and spleen showed significant atrophy from one month to three months after irradiation. A high level of apoptosis in thymus and spleen were obtained and the latter was more vulnerable, also, high level of inflammatory cytokines were found. Genes (c-kit, Rag1, Rag2 and Sca1) related to thymus lymphocytes’ development were down-regulated. Conclusion: Local area radiation in the rat brain would cause the immunosuppression, especially, the losing of cell-mediated immune functions. In this model, radiation caused inflammation and then induced apoptosis of cells in the immune organs, which contributed to immunosuppression.

  18. Comparative study of the usefulness of low energy Cs(+), Xe(+), and O(2)(+) ions for depth profiling amino-acid and sugar films.

    PubMed

    Wehbe, Nimer; Houssiau, Laurent

    2010-12-15

    This work reports a comparative study on the capability of low energy primary ion beams for depth profiling nonpolymeric molecules including amino-acid and sugar layers. Due to their different behavior regarding depth profiling, phenylalanine and trehalose molecules are chosen as reference systems. Each molecule was dissolved in suitable solvent prior to spin-coating on clean silicon wafer. The film thicknesses were in the order of 70 and 100 nm for phenylalanine and trehalose respectively. Depth profiling feasibility were assessed first using Cs(+) as reactive sputtering ion at various energies. The results obtained under Cs(+) sputtering ions are compared afterward to those obtained under Xe(+) sputtering ions which are inert and have a mass very similar to Cs(+). In order to investigate the effect of oxygen, depth profiling are also performed using either Xe(+) under oxygen flooding or O(2)(+) as sputtering ions. While phenylalanine could be depth profiled successfully using Cs(+) ions, Xe(+) and O(2)(+) ions failed to retain any characteristic signal. The sputtering yields measured as a function of the ion beam energies were higher using Cs(+), in particular at low energies. The chemical reactivity of the cesium atoms being implanted during the sputtering process helps to prevent the loss of the molecular phenylalanine signal. In contrast, depth profiling of trehalose was more successful upon Xe(+) and O(2)(+) compared to Cs(+). In this case the sputtering yields were higher if Xe(+) primary ion is employed instead of Cs(+). The different trends observed in this study are interpreted using arguments involving the reactivity of the sputtering ions. PMID:21073169

  19. Space Weathering on Primitive Asteroids: Ion Irradiation of Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Lantz, C.; Brunetto, R.; Barucci, M. A.

    2015-11-01

    We simulate space weathering processes on primitive bodies using ion implantation as a simulation of solar wind irradiation. The laboratory analogs we irradiate and analyze with visible to mid-infrared spectroscopy are carbonaceous chondrites.

  20. Materials Modification Under Ion Irradiation: JANNUS Project

    SciTech Connect

    Serruys, Y.; Trocellier, P.; Trouslard, Ph.

    2004-12-01

    JANNUS (Joint Accelerators for Nano-Science and Nuclear Simulation) is a project designed to study the modification of materials using multiple ion beams and in-situ TEM observation. It will be a unique facility in Europe for the study of irradiation effects, the simulation of material damage due to irradiation and in particular of combined effects. The project is also intended to bring together experimental and modelling teams for a mutual fertilisation of their activities. It will also contribute to the teaching of particle-matter interactions and their applications. JANNUS will be composed of three accelerators with a common experimental chamber and of two accelerators coupled to a 200 kV TEM.

  1. Electron irradiation effect on bubble formation and growth in a sodium borosilicate glass

    SciTech Connect

    Chen, X.; Birtcher, R. C.; Donnelly, S. E.

    2000-02-08

    In this study, the authors studied simultaneous and intermittent electron irradiation effects on bubble growth in a simple sodium borosilicate glass during Xe ion implantation at 200 C. Simultaneous electron irradiation increases the average bubble size in the glass. This enhanced diffusion is also shown by the migration of Xe from bubbles into the matrix when the sample is irradiated by an electron beam after the Xe implantation.

  2. Effects of swift heavy ions irradiation parameters on optical properties of muscovite mica

    E-print Network

    Zhang, Sheng-Xia; Zeng, Jian; Song, Yin; Mo, Dan; Yao, Hui-Jun; Duan, Jing-Lai; Sun, You-Mei; Hou, Ming-Dong

    2014-01-01

    Muscovite mica sheets with a thickness of 25 {\\mu}m were irradiated by various kinds of swift heavy ions (Sn, Xe and Bi) in HIRFL. The fluences ranged from 1$\\times$10^{10} ions/cm^2 to 8$\\times$10^{11} ions/cm^2. The electronic energy loss (dE/dx)_e was increased from 14.7 keV/nm to 31.2 keV/nm. The band gap and Urbach energy of pristine and irradiated mica were analyzed by ultraviolet- visible spectroscopy. Periodic fringes in long wave length of the absorption spectra caused by interference phenomenon, were disturbed as the (dE/dx)_e increased. It was suggested that the chemical bonds between Tetrahedral-Octohedral-Tetrahedral (TOT) layers of mica were destroyed. Thus the smooth surface was cleaved after irradiation. The band gap was narrowed down with the increasing (dE/dx)_e and fluences. The values of Urbach energy were increased as the (dE/dx)_e and fluences gradually increased. It was indicated that the amount of defects and the proportion of amorphous structure were increased in mica irradiated under...

  3. Amorphization and dynamic annealing of hexagonal SiC upon heavy-ion irradiation: Effects on swelling and mechanical properties

    SciTech Connect

    Kerbiriou, Xavier; Costantini, Jean-Marc; Sauzay, Maxime; Sorieul, Stephanie; Thome, Lionel

    2009-04-01

    Structural, mechanical, and dimensional evolutions of silicon carbide (SiC) induced by heavy-ion irradiations are studied by means of Rutherford backscattering spectrometry and channeling (RBS/C), nanoindentation, and surface profilometry measurements. 4H- and 6H-SiC single crystals were irradiated with 4 MeV Au{sup 2+} and 4 MeV Xe{sup +} ions at room temperature (RT) or 400 deg. C. Using a Monte Carlo program to simulate the RBS/C spectra (MCCHASY code), we find that Au ion irradiation at RT induces a total silicon sublattice disorder related to full amorphization at a dose of about 0.4 displacement per atom (dpa). A two-step damage process is found on the basis of the disordered fractions deduced from RBS/C data. Complete amorphization cannot be reached upon both Au and Xe ion irradiations at 400 deg. C up to about 26 dpa because of the dynamic annealing of defects. When complete amorphization is reached at RT, the Young's modulus and Berkovich hardness of irradiated 6H-SiC samples are lower by, respectively, 40% and 45% than those of the virgin crystals. The out-of-plane expansion measured by surface profilometry increases versus irradiation dose and the saturation value measured in the completely amorphous layer (normalized to the ion projected range) is close to 25%. We show that the modifications of the macroscopic properties are mainly due to the amorphization of the material. The macroscopic elasticity constants and dimensional properties are predicted for a composite material made of crystalline matrix containing dispersed amorphous inclusions using simple analytical homogenization models. Voigt's model seems to give the best approximation for disordered fractions larger than 20% in the second step of the damage process.

  4. Irradiation of Nuclear Track Emulsions with Thermal Neutrons, Heavy Ions, and Muons

    E-print Network

    D. A. Artemenkov; V. Bradnova; A. A. Zaitsev; P. I. Zarubin; I. G. Zarubina; R. R. Kattabekov; K. Z. Mamatkulov; V. V. Rusakova

    2015-08-11

    Exposures of test samples of nuclear track emulsion were analyzed. Angular and energy correlations of products originating from the thermal-neutron-induced reaction n$_{th} + ^{10}$B $\\rightarrow ^{7}$Li $+ (\\gamma) + \\alpha$ were studied in nuclear tack emulsions enriched in boron. Nuclear track emulsions were also irradiated with $^{86}$Kr$^{+17}$ and $^{132}$Xe$^{+26}$ of energy about 1.2 MeV per nucleon. Measurements of ranges of heavy ions in nuclear track emulsions made it possible to determine their energies on the basis of the SRIM model. The formation of high-multiplicity nuclear stars was observed upon irradiating nuclear track emulsions with ultrarelativistic muons. Kinematical features studied in this exposure of nuclear track emulsions for events of the muon-induced splitting of carbon nuclei to three alpha particles are indicative of the nuclear-diffraction interaction mechanism.

  5. Colloidal assemblies modied by ion irradiation E. Snoeks a

    E-print Network

    Polman, Albert

    for free-stand- ing thin ®lms composed of a metallic glass irradi- ated at energies of several 100 MeV [2,3], causes the irradiated region to expand in the direction perpendicular to the ion beam, and to shrinkV/nm) and low directional straggle in the ion trajectory that cause a cylindrically shaped narrow thermal spike

  6. A comparative study of track registration characteristics of Makrofol-(KG, KL & N) polycarbonate to 136Xe ions

    NASA Astrophysics Data System (ADS)

    Kumar, Ashavani; Prasad, Rajendra

    2000-07-01

    Solid state nuclear track detectors (SSNTDs) are widely used detectors for low as well as high-energy ionography. In the present work a comparative study of track registration characteristics of 136Xe ions in different types of Makrofol polycarbonates viz. Makrofol-KG, KL & N have been done. The etched track parameters viz. bulk etch rate, track etch rate, etch rate ratio, cone angle and etching efficiency were calculated. The variations of etching rates with temperature were found to be exponential and follow the Arrhenius equation. The values of activation energy for bulk and track etching were also calculated. Maximum etchable track length/range were also obtained and compared with the theoretical values obtained from computer program RANGE (DEDXH). From the results it is found that the polycarbonates having same chemical composition manufactured by different chemical processes have slightly different etching behavior.

  7. Fabrication of Step-and-Flash Imprint Lithography (S-FIL) templates using XeF2 enhanced focused ion-beam etching

    NASA Astrophysics Data System (ADS)

    Kettle, J.; Hoyle, R. T.; Dimov, S.

    2009-09-01

    The fabrication of Step-and-Flash Imprint Lithography (S-FIL) templates with line widths of 50 nm is described in this work. The structures have been patterned using a Ga+ focused ion beam (FIB) in a quartz template. FIB milling is generally accompanied with re-deposition effects, which represent a hindrance to densely patterned nanostructures required in most NIL applications. To reduce these re-deposition effects, in this research, xenon difluoride (XeF2) enhanced FIB etching was applied that also increases the material removal rates in comparison to pure kinetic ion sputtering. To optimise the process when using XeF2 gas the following ion scanning parameters have been examined: ion dose, beam current, dwell time and beam overlap (step size). It has been found that the assisting gases at very low doses do not bring significant etching enhancements whilst the sputtering rates have increased at high doses. Using the XeF2 gas-assisted etching, FIB structuring has been used to fabricate <100 nm structures onto quartz S-FIL templates. The presence of XeF2 considerably enhances the etching rate of quartz without any significant negative effects on the spatial resolution of the FIB lithographic process and reduces the template processing time.

  8. Concurrent in situ ion irradiation transmission electron microscope

    DOE PAGESBeta

    Hattar, K.; Bufford, D. C.; Buller, D. L.

    2014-08-29

    An in situ ion irradiation transmission electron microscope has been developed and is operational at Sandia National Laboratories. This facility permits high spatial resolution, real time observation of electron transparent samples under ion irradiation, implantation, mechanical loading, corrosive environments, and combinations thereof. This includes the simultaneous implantation of low-energy gas ions (0.8–30 keV) during high-energy heavy ion irradiation (0.8–48 MeV). In addition, initial results in polycrystalline gold foils are provided to demonstrate the range of capabilities.

  9. Emulation of reactor irradiation damage using ion beams

    SciTech Connect

    Was, G. S.; Jiao, Z.; Getto, E.; Sun, K.; Monterrosa, A. M.; Maloy, S. A.; Anderoglu, O.; Sencer, B. H.; Hackett, M.

    2014-06-14

    The continued operation of existing light water nuclear reactors and the development of advanced nuclear reactor depend heavily on understanding how damage by radiation to levels degrades materials that serve as the structural components in reactor cores. The first high dose ion irradiation experiments on a ferritic-martensitic steel showing that ion irradiation closely emulates the full radiation damage microstructure created in-reactor are described. Ferritic-martensitic alloy HT9 (heat 84425) in the form of a hexagonal fuel bundle duct (ACO-3) accumulated 155 dpa at an average temperature of 443°C in the Fast Flux Test Facility (FFTF). Using invariance theory as a guide, irradiation of the same heat was conducted using self-ions (Fe++) at 5 MeV at a temperature of 460°C and to a dose of 188 displacements per atom. The void swelling was nearly identical between the two irradiation and the size and density of precipitates and loops following ion irradiation are within a factor of two of those for neutron irradiation. The level of agreement across all of the principal microstructure changes between ion and reactor irradiation establishes the capability of tailoring ion irradiation to emulate the reactor-irradiated microstructure.

  10. Emulation of reactor irradiation damage using ion beams

    DOE PAGESBeta

    Was, G. S.; Jiao, Z.; Getto, E.; Sun, K.; Monterrosa, A. M.; Maloy, S. A.; Anderoglu, O.; Sencer, B. H.; Hackett, M.

    2014-06-14

    The continued operation of existing light water nuclear reactors and the development of advanced nuclear reactor depend heavily on understanding how damage by radiation to levels degrades materials that serve as the structural components in reactor cores. The first high dose ion irradiation experiments on a ferritic-martensitic steel showing that ion irradiation closely emulates the full radiation damage microstructure created in-reactor are described. Ferritic-martensitic alloy HT9 (heat 84425) in the form of a hexagonal fuel bundle duct (ACO-3) accumulated 155 dpa at an average temperature of 443°C in the Fast Flux Test Facility (FFTF). Using invariance theory as a guide,more »irradiation of the same heat was conducted using self-ions (Fe++) at 5 MeV at a temperature of 460°C and to a dose of 188 displacements per atom. The void swelling was nearly identical between the two irradiation and the size and density of precipitates and loops following ion irradiation are within a factor of two of those for neutron irradiation. The level of agreement across all of the principal microstructure changes between ion and reactor irradiation establishes the capability of tailoring ion irradiation to emulate the reactor-irradiated microstructure.« less

  11. Theoretical investigation of HNgNH{sub 3}{sup +} ions (Ng = He, Ne, Ar, Kr, and Xe)

    SciTech Connect

    Gao, Kunqi; Sheng, Li

    2015-04-14

    The equilibrium geometries, harmonic frequencies, and dissociation energies of HNgNH{sub 3}{sup +} ions (Ng = He, Ne, Ar, Kr, and Xe) were investigated using the following method: Becke-3-parameter-Lee-Yang-Parr (B3LYP), Boese-Matrin for Kinetics (BMK), second-order Møller-Plesset perturbation theory (MP2), and coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)). The results indicate that HHeNH{sub 3}{sup +}, HArNH{sub 3}{sup +}, HKrNH{sub 3}{sup +}, and HXeNH{sub 3}{sup +} ions are metastable species that are protected from decomposition by high energy barriers, whereas the HNeNH{sub 3}{sup +} ion is unstable because of its relatively small energy barrier for decomposition. The bonding nature of noble-gas atoms in HNgNH{sub 3}{sup +} was also analyzed using the atoms in molecules approach, natural energy decomposition analysis, and natural bond orbital analysis.

  12. I-Xe systematics in LL chondrites

    NASA Technical Reports Server (NTRS)

    Bernatowicz, T. J.; Podosek, F. A.; Swindle, T. D.; Honda, M.

    1988-01-01

    A stepwise heating analysis of Ar and Xe data from five neutron-irradiated whole rock LL chondrites (Soko Banja, Alta Ameen, Tuxtuac, Guidder, and Olivenza) is presented, emphasizing the complicated thermal history of ordinary chondrites. None of the present meteorites show a well-defined (Ar-40)-(Ar-39) apparent age plateau comprised of more than two release fractions. Most of the samples are found to yield well-defined high-temperature correlations between Xe-129/Xe-130 and Xe-128/Xe-130, and thus determinations of I-129/I-127 and Xe-129/Xe-130 at the time of isotopic closure for Xe. As in the case of other ordinary chondrites, the I-Xe systematics for LL chondrites correlate neither with a metamorphic grade nor with chronologies based opon other methods.

  13. Influence of irradiation with swift heavy ions on multilayer Si/SiO{sub 2} heterostructures

    SciTech Connect

    Kachurin, G. A. Cherkova, S. G.; Marin, D. V.; Volodin, V. A.; Cherkov, A. G.; Antonenko, A. Kh.; Kamaev, G. N.; Skuratov, V. A.

    2013-03-15

    The influence of Xe ions with an energy of 167 MeV and a dose in the range 10{sup 12}-3 Multiplication-Sign 10{sup 13} cm{sup -2} on heterostructures consisting of six pairs of Si/SiO{sub 2} layers with the thicknesses {approx}8 and {approx}10 nm, correspondingly, is studied. As follows from electron microscopy data, the irradiation breaks down the integrity of the layers. At the same time, Raman studies give evidence for the enhancement of scattering in amorphous silicon. In addition, a yellow-orange band inherent to small-size Si clusters released from SiO{sub 2} appears in the photoluminescence spectra. Annealing at 800 Degree-Sign C recovers the SiO{sub 2} network, whereas annealing at 1100 Degree-Sign C brings about the appearance of a more intense photoluminescence peak at {approx}780 nm typical of Si nanocrystals. The 780-nm-peak intensity increases, as the irradiation dose is increased. It is thought that irradiation produces nuclei, which promote Si-nanocrystal formation upon subsequent annealing. The processes occur within the tracks due to strong heating because of ionization losses of the ions.

  14. Enhanced electrochemical etching of ion irradiated silicon by localized amorphization

    SciTech Connect

    Dang, Z. Y.; Breese, M. B. H.; Lin, Y.; Tok, E. S.; Vittone, E.

    2014-05-12

    A tailored distribution of ion induced defects in p-type silicon allows subsequent electrochemical anodization to be modified in various ways. Here we describe how a low level of lattice amorphization induced by ion irradiation influences anodization. First, it superposes a chemical etching effect, which is observable at high fluences as a reduced height of a micromachined component. Second, at lower fluences, it greatly enhances electrochemical anodization by allowing a hole diffusion current to flow to the exposed surface. We present an anodization model, which explains all observed effects produced by light ions such as helium and heavy ions such as cesium over a wide range of fluences and irradiation geometries.

  15. Ion irradiation testing of Improved Accident Tolerant Cladding Materials

    SciTech Connect

    Anderoglu, Osman; Tesmer, Joseph R.; Maloy, Stuart A.

    2014-01-14

    This report summarizes the results of ion irradiations conducted on two FeCrAl alloys (named as ORNL A&B) for improving the accident tolerance of LWR nuclear fuel cladding. After irradiation with 1.5 MeV protons to ~0.5 to ~1 dpa and 300°C nanoindentations were performed on the cross-sections along the ion range. An increase in hardness was observed in both alloys. Microstructural analysis shows radiation induced defects.

  16. Heavy-ion irradiation induced diamond formation in carbonaceous materials.

    SciTech Connect

    Daulton, T. L.

    1999-01-08

    The basic mechanisms of metastable phase formation produced under highly non-equilibrium thermodynamic conditions within high-energy particle tracks are investigated. In particular, the possible formation of diamond by heavy-ion irradiation of graphite at ambient temperature is examined. This work was motivated, in part, by earlier studies which discovered nanometer-grain polycrystalline diamond aggregates of submicron-size in uranium-rich carbonaceous mineral assemblages of Precambrian age. It was proposed that the radioactive decay of uranium formed diamond in the fission particle tracks produced in the carbonaceous minerals. To test the hypothesis that nanodiamonds can form by ion irradiation, fine-grain polycrystalline graphite sheets were irradiated with 400 MeV Kr ions. The ion irradiated graphite (and unirradiated graphite control) were then subjected to acid dissolution treatments to remove the graphite and isolate any diamonds that were produced. The acid residues were then characterized by analytical and high-resolution transmission electron microscopy. The acid residues of the ion-irradiated graphite were found to contain ppm concentrations of nanodiamonds, suggesting that ion irradiation of bulk graphite at ambient temperature can produce diamond.

  17. The effects of swift heavy-ion irradiation on helium-ion-implanted silicon

    NASA Astrophysics Data System (ADS)

    Li, B. S.; Du, Y. Y.; Wang, Z. G.; Shen, T. L.; Li, Y. F.; Yao, C. F.; Sun, J. R.; Cui, M. H.; Wei, K. F.; Zhang, H. P.; Shen, Y. B.; Zhu, Y. B.; Pang, L. L.

    2014-10-01

    Cross-sectional transmission electron microscopy (XTEM) was used to study the effects of irradiation with swift heavy ions on helium-implanted silicon. <1 0 0>-oriented silicon wafers were implanted with 30 keV helium to a dose of 3 × 1016 He+/cm2 at 600 K. Subsequently, the helium-implanted Si wafers were irradiated with 792 MeV argon ions. The He bubbles and extended defects in the wafers were examined via XTEM analysis. The results reveal that the mean diameter of the He bubbles increases upon Ar-ion irradiation, while the number density of the He bubbles decreases. The microstructure of the He bubbles observed after Ar-ion irradiation is comparable to that observed after annealing at 1073 K for 30 min. Similarly, the mean size of the extended defects, i.e., Frank loops, increases after Ar-ion irradiation. Possible mechanisms are discussed.

  18. The interactions of high-energy, highly charged Xe ions with buckyballs

    SciTech Connect

    Ali, R.; Berry, H.G.; Cheng, S.

    1994-12-31

    Ionization and fragmentation have been measured for C{sub 60} molecules bombarded by highly charged (up to 35+) xenon ions with energies ranging up to 625 MeV. The observed mass distribution of positively charged fragments is explained in terms of a theoretical model indicating that the total interaction cross section contains roughly equal contributions from (a) excitation of the giant plasmon resonance, and (b) large-energy-transfer processes that lead to multiple fragmentation of the molecule. Preliminary results of measurements on VUV photons emitted in these interactions are also presented.

  19. Anomalous Plastic Deformation and Sputtering of Ion Irradiated Silicon Nanowires

    PubMed Central

    2015-01-01

    Silicon nanowires of various diameters were irradiated with 100 keV and 300 keV Ar+ ions on a rotatable and heatable stage. Irradiation at elevated temperatures above 300 °C retains the geometry of the nanostructure and sputtering can be gauged accurately. The diameter dependence of the sputtering shows a maximum if the ion range matches the nanowire diameter, which is in good agreement with Monte Carlo simulations based on binary collisions. Nanowires irradiated at room temperature, however, amorphize and deform plastically. So far, plastic deformation has not been observed in bulk silicon at such low ion energies. The magnitude and direction of the deformation is independent of the ion-beam direction and cannot be explained with mass-transport in a binary collision cascade but only by collective movement of atoms in the collision cascade with the given boundary conditions of a high surface to volume ratio. PMID:25951108

  20. Anomalous Plastic Deformation and Sputtering of Ion Irradiated Silicon Nanowires.

    PubMed

    Johannes, Andreas; Noack, Stefan; Wesch, Werner; Glaser, Markus; Lugstein, Alois; Ronning, Carsten

    2015-06-10

    Silicon nanowires of various diameters were irradiated with 100 keV and 300 keV Ar(+) ions on a rotatable and heatable stage. Irradiation at elevated temperatures above 300 °C retains the geometry of the nanostructure and sputtering can be gauged accurately. The diameter dependence of the sputtering shows a maximum if the ion range matches the nanowire diameter, which is in good agreement with Monte Carlo simulations based on binary collisions. Nanowires irradiated at room temperature, however, amorphize and deform plastically. So far, plastic deformation has not been observed in bulk silicon at such low ion energies. The magnitude and direction of the deformation is independent of the ion-beam direction and cannot be explained with mass-transport in a binary collision cascade but only by collective movement of atoms in the collision cascade with the given boundary conditions of a high surface to volume ratio. PMID:25951108

  1. Characterization of swift heavy ion irradiation damage in ceria

    SciTech Connect

    Yablinsky, Clarissa; Devanathan, Ram; Pakarinen, Janne; Gan, Jian; Severin, Daniel; Trautmann, Christina; Allen, T. R.

    2015-05-14

    We have examined microstructural evolution in irradiated ceria (CeO2) using swift heavy ion irradiation, electron microscopy, and atomistic simulation. CeO2, a UO2 fuel surrogate, was irradiated with gold ions at an energy of 1 GeV to fluences up to 1x1014 ions/cm2. Transmission electron microscopy accompanied by electron energy loss spectroscopy showed that the ion tracks were of similar size at all fluences, and that there was no chemical change in the ion track core. Classical molecular dynamics simulations of thermal spikes in CeO2 with energy deposition of 12 and 36 keV/nm show damage consisting of isolated point defects at the lower energy and defect clusters at 36 keV/nm, with no amorphization at either energy. Inferences are drawn from modeling about density changes in the ion track and the formation of interstitial loops that shed light on features observed by electron microscopy of swift heavy ion irradiated ceria.

  2. University of Wisconsin Ion Beam Laboratory: A facility for irradiated materials and ion beam analysis

    SciTech Connect

    Field, K. G.; Wetteland, C. J.; Cao, G.; Maier, B. R.; Gerczak, T. J.; Kriewaldt, K.; Sridharan, K.; Allen, T. R.; Dickerson, C.; Field, C. R.

    2013-04-19

    The University of Wisconsin Ion Beam Laboratory (UW-IBL) has recently undergone significant infrastructure upgrades to facilitate graduate level research in irradiated materials phenomena and ion beam analysis. A National Electrostatics Corp. (NEC) Torodial Volume Ion Source (TORVIS), the keystone upgrade for the facility, can produce currents of hydrogen ions and helium ions up to {approx}200 {mu}A and {approx}5 {mu}A, respectively. Recent upgrades also include RBS analysis packages, end station developments for irradiation of relevant material systems, and the development of an in-house touch screen based graphical user interface for ion beam monitoring. Key research facilitated by these upgrades includes irradiation of nuclear fuels, studies of interfacial phenomena under irradiation, and clustering dynamics of irradiated oxide dispersion strengthened steels. The UW-IBL has also partnered with the Advanced Test Reactor National Scientific User Facility (ATR-NSUF) to provide access to the irradiation facilities housed at the UW-IBL as well as access to post irradiation facilities housed at the UW Characterization Laboratory for Irradiated Materials (CLIM) and other ATR-NSUF partner facilities. Partnering allows for rapid turnaround from proposed research to finalized results through the ATR-NSUF rapid turnaround proposal system. An overview of the UW-IBL including CLIM and relevant research is summarized.

  3. University of Wisconsin Ion Beam Laboratory: A facility for irradiated materials and ion beam analysis

    NASA Astrophysics Data System (ADS)

    Field, K. G.; Wetteland, C. J.; Cao, G.; Maier, B. R.; Dickerson, C.; Gerczak, T. J.; Field, C. R.; Kriewaldt, K.; Sridharan, K.; Allen, T. R.

    2013-04-01

    The University of Wisconsin Ion Beam Laboratory (UW-IBL) has recently undergone significant infrastructure upgrades to facilitate graduate level research in irradiated materials phenomena and ion beam analysis. A National Electrostatics Corp. (NEC) Torodial Volume Ion Source (TORVIS), the keystone upgrade for the facility, can produce currents of hydrogen ions and helium ions up to ˜200 ?A and ˜5 ?A, respectively. Recent upgrades also include RBS analysis packages, end station developments for irradiation of relevant material systems, and the development of an in-house touch screen based graphical user interface for ion beam monitoring. Key research facilitated by these upgrades includes irradiation of nuclear fuels, studies of interfacial phenomena under irradiation, and clustering dynamics of irradiated oxide dispersion strengthened steels. The UW-IBL has also partnered with the Advanced Test Reactor National Scientific User Facility (ATR-NSUF) to provide access to the irradiation facilities housed at the UW-IBL as well as access to post irradiation facilities housed at the UW Characterization Laboratory for Irradiated Materials (CLIM) and other ATR-NSUF partner facilities. Partnering allows for rapid turnaround from proposed research to finalized results through the ATR-NSUF rapid turnaround proposal system. An overview of the UW-IBL including CLIM and relevant research is summarized.

  4. Studies of the radial distribution of Pu, Xe and Cs in irradiated thermal-reactor UO 2 fuel, using an electron probe microanalyser

    NASA Astrophysics Data System (ADS)

    Pearce, J. H.; Sumerling, R.; Hargreaves, R.

    1983-05-01

    An electron probe microanalyser (EPMA) has been used to measure the radial distribution of plutonium, xenon and caesium in irradiated AGR and water reactor UO 2 fuel pellets, with burn-ups in the range 4 to 35 GWd/t. In the cooler parts of the fuel (at 0.8 pellet radius) there was generally good agreement between measured and estimated values for the concentrations of retained fission products. In both types of fuel enhanced concentrations of plutonium and fission products were present in a narrow zone at the pellet surface, due to epithermal neutron capture effects. In the more highly rated fuel at ~35 W/g the central hotter region of fuel was depleted in xenon and to a lesser extent in caesium. This zone of Xe and Cs depletion corresponds to the region in which fission gas diffuses to grain boundaries to form bubbles which grow and interlink to allow gas release from the fuel.

  5. Forsterite Amorphisation by Ion Irradiation: Monitoring by Infrared Spectroscopy

    E-print Network

    J. R. Brucato; G. Strazzulla; G. Baratta; L. Colangeli

    2003-07-23

    We present experimental results on crystal--amorphous transition of forsterite (Mg2SiO4) silicate under ion irradiation. The aim of this work is to study the structural evolution of one of the most abundant crystalline silicates observed in space driven by ion irradiation. To this aim, forsterite films have been sythesised in laboratory and irradiated with low energy (30--60 keV) ion beams. Structural changes during irradiation with H+, He+, C+, and Ar++ have been observed and monitored by infrared spectroscopy. The fraction of crystalline forsterite converted into amorphous is a function of the energy deposited by nuclear collision by ions in the target. Laboratory results indicate that ion irradiation is a mechanism potentially active in space for the amorphisation of silicates. Physical properties obtained in this work can be used to model the evolution of silicate grains during their life cycle from evolved stars, through different interstellar environments and up to be incorporated in Solar System objects.

  6. Ion and neutral energy flux distributions to the cathode in glow discharges in Ar/Ne and Xe/Ne mixtures

    NASA Astrophysics Data System (ADS)

    Capdeville, H.; Pédoussat, C.; Pitchford, L. C.

    2002-02-01

    The work presented in the article is a study of the heavy particle (ion and neutral) energy flux distributions to the cathode in conditions typical of discharges used for luminous signs for advertising ("neon" signs). The purpose of this work is to evaluate the effect of the gas mixture on the sputtering of the cathode. We have combined two models for this study: a hybrid model of the electrical properties of the cathode region of a glow discharge and a Monte Carlo simulation of the heavy particle trajectories. Using known sputtering yields for Ne, Ar, and Xe on iron cathodes, we estimate the sputtered atom flux for mixtures of Ar/Ne and Xe/Ne as a function of the percent neon in the mixture.

  7. Inner-shell photoionization and core-hole decay of Xe and XeF2

    NASA Astrophysics Data System (ADS)

    Southworth, Stephen H.; Wehlitz, Ralf; Picón, Antonio; Lehmann, C. Stefan; Cheng, Lan; Stanton, John F.

    2015-06-01

    Photoionization cross sections and partial ion yields of Xe and XeF2 from Xe 3d5/2, Xe 3d3/2, and F 1s subshells in the 660-740 eV range are compared to explore effects of the F ligands. The Xe 3d-?f continuum shape resonances dominate the photoionization cross sections of both the atom and molecule, but prominent resonances appear in the XeF2 cross section due to nominal excitation of Xe 3d and F 1s electrons to the lowest unoccupied molecular orbital (LUMO), a delocalized anti-bonding MO. Comparisons of the ion products from the atom and molecule following Xe 3d photoionization show that the charge-state distribution of Xe ions is shifted to lower charge states in the molecule along with production of energetic F+ and F2+ ions. This suggests that, in decay of a Xe 3d core hole, charge is redistributed to the F ligands and the system dissociates due to Coulomb repulsion. The ion products from excitation of the F 1s-LUMO resonance are different and show strong increases in the yields of Xe+ and F+ ions. The subshell ionization thresholds, the LUMO resonance energies, and their oscillator strengths are calculated by relativistic coupled-cluster methods and agree well with measurements.

  8. Inner-shell photoionization and core-hole decay of Xe and XeF2.

    PubMed

    Southworth, Stephen H; Wehlitz, Ralf; Picón, Antonio; Lehmann, C Stefan; Cheng, Lan; Stanton, John F

    2015-06-14

    Photoionization cross sections and partial ion yields of Xe and XeF2 from Xe 3d(5/2), Xe 3d(3/2), and F 1s subshells in the 660-740 eV range are compared to explore effects of the F ligands. The Xe 3d-?f continuum shape resonances dominate the photoionization cross sections of both the atom and molecule, but prominent resonances appear in the XeF2 cross section due to nominal excitation of Xe 3d and F 1s electrons to the lowest unoccupied molecular orbital (LUMO), a delocalized anti-bonding MO. Comparisons of the ion products from the atom and molecule following Xe 3d photoionization show that the charge-state distribution of Xe ions is shifted to lower charge states in the molecule along with production of energetic F(+) and F(2+) ions. This suggests that, in decay of a Xe 3d core hole, charge is redistributed to the F ligands and the system dissociates due to Coulomb repulsion. The ion products from excitation of the F 1s-LUMO resonance are different and show strong increases in the yields of Xe(+) and F(+) ions. The subshell ionization thresholds, the LUMO resonance energies, and their oscillator strengths are calculated by relativistic coupled-cluster methods and agree well with measurements. PMID:26071705

  9. Raman measurements in silica glasses irradiated with energetic ions

    SciTech Connect

    Saavedra, R. Martin, P.; Vila, R.; León, M.; Jiménez-Rey, D.; Girard, S.; Boukenter, A.; Ouerdane, Y.

    2014-10-21

    Ion irradiation with energetic He{sup +} (2.5 MeV), O{sup 4+} (13.5 MeV), Si{sup 4+} (24.4 MeV) and Cu{sup 7+} (32.6 MeV) species at several fluences (from 5 × 10{sup 12} to 1.65 × 10{sup 15} ion/cm{sup 2}) were performed in three types of SiO{sub 2} glasses with different OH content (KU1, KS-4V and Infrasil 301). After ion implantation the Raman spectra were measured and compared with the spectra of unirradiated samples. Irradiated samples of the three fused silica grades exhibit changes in the broad and asymmetric R-band (?{sub 1} around 445 cm{sup ?1}), in D{sub 1} (490 cm?1) and D{sub 2} (605 cm{sup ?1}) bands associated to small-membered rings. The D{sub 2} band shows an increase with increasing fluences for different ions, indicating structural changes. Raman spectra of ion-irradiated samples were compared with the spectra of neutron irradiated samples at fluences 10{sup 17} n/cm{sup 2} and 1018 n/cm{sup 2}. Macroscopic surface cracking was detected, mainly at fluences corresponding to deposited energies between 10{sup 23} eV/cm{sup 3} and 10{sup 24} eV/cm{sup 3} (after ion beam shutdown)

  10. Atomistic simulation of damage production by atomic and molecular ion irradiation in GaN

    E-print Network

    Nordlund, Kai

    . Related Articles Fabricating high-density magnetic storage elements by low-dose ion beam irradiation ApplAtomistic simulation of damage production by atomic and molecular ion irradiation in GaN M. W of nano-clusters by ion-beam irradiation Appl. Phys. Lett. 101, 103112 (2012) Universal mechanism for ion

  11. Swift heavy ion irradiation of zirconium phosphate of various forms

    NASA Astrophysics Data System (ADS)

    Szirtes, L.; Megyeri, J.; Kuzmann, E.; Havancsák, K.

    2003-06-01

    The zirconium phosphate and its various derivatives have good resistance against ionization radiation, as it was found earlier during the irradiation of them with ?-rays of high energy. Continuing these experiments amorphous and crystalline (both ?- and ?-forms) zirconium phosphate, its monosodium, and propylamine intercalated forms were irradiated with a fluence of 10 11-10 14 ion cm -2 with swift heavy ions of 203Bi and 84Kr. The irradiation was also performed with Si containing zirconium phosphate. The structure of the materials was characterized by XRD method. The comparison of the powder diffraction patterns reveals that the irradiation has practically no effect on the ?-zirconium phosphate, while the other materials more or less destroyed and some of them became amorphous. The propylamine intercalate form of zirconium phosphate is decomposed on ?-ZrP and organic radical.

  12. Influence of substrate and ion irradiation on the magnetic properties of laser-deposited CoFe films

    NASA Astrophysics Data System (ADS)

    Gupta, Ratnesh; Lieb, K. P.; Müller, G. A.; Weisheit, M.; Zhang, K.

    2006-05-01

    Highly textured FeCo thin films have been prepared by pulsed laser deposition on Si(1 0 0) and MgO(1 0 0) single crystals. The influence of the microstructure on the magnetic properties has been studied using the magneto-optical Kerr effect and vibrating sample magnetometry. The in-plane coercivity of the films deposited on Si and MgO was 28 Oe and 12 Oe, respectively. A fourfold in-plane magnetic anisotropy has been observed for a film deposited on MgO(1 0 0), in contrast to the isotropic pattern of the film deposited on Si. The films have then been irradiated under an in-plane magnetic field of 104 Oe by 40-keV Ne- and 200-keV Xe-ions, at a fluence of 1 × 10 15 ions/cm 2. For Xe-ions, the film deposited on Si(1 0 0) developed a twofold magnetic anisotropy, while the film on MgO exhibited only slight changes of the fourfold anisotropy.

  13. Response of Strontium Titanate to Ion and Electron Irradiation

    SciTech Connect

    Zhang, Yanwen; Lian, Jie; Zhu, Zihua; Bennett, Wendy D.; Saraf, Laxmikant V.; Rausch, Julie L.; Hendricks, Catherine A.; Ewing, R. C.; Weber, William J.

    2009-04-20

    Response of strontium titanate (SrTiO3) to ion and electron irradiation is studied at room temperature. For an accurate energy to depth conversion and a better determination of ion-induced disorder profile from Rutherford backscattering spectrometry measurement, a detailed iterative procedure is described and applied to ion channeling spectra to determine the dechanneling yield and the disorder profiles for the Sr and Ti sublattices. The result shows a large underestimation in disorder depth, ~ 40% at the damage peak, which indicates a large overestimation of the electronic stopping power for 1.0 MeV Au ions in SrTiO3 predicted by the SRIM (Stopping and Range of Ions in Matter) code. Overestimation of heavy ion stopping power may lead to an overestimation of the critical dose for amorphization. The current study also demonstrates possible ionization effects in SrTiO3 under ion and electron irradiation. Pre-amorphized SrTiO3 exhibits strong ionization-induced epitaxial recovery at the amorphous/crystalline interface under electron irradiation.

  14. Surface modification of multilayer graphene using Ga ion irradiation

    SciTech Connect

    Wang, Quan; Shao, Ying; Ge, Daohan; Ren, Naifei; Yang, Qizhi

    2015-04-28

    The effect of Ga ion irradiation intensity on the surface of multilayer graphene was examined. Using Raman spectroscopy, we determined that the irradiation caused defects in the crystal structure of graphene. The density of defects increased with the increase in dwell times. Furthermore, the strain induced by the irradiation changed the crystallite size and the distance between defects. These defects had the effect of doping the multilayer graphene and increasing its work function. The increase in work function was determined using contact potential difference measurements. The surface morphology of the multilayer graphene changed following irradiation as determined by atomic force microscopy. Additionally, the adhesion between the atomic force microscopy tip and sample increased further indicating that the irradiation had caused surface modification, important for devices that incorporate graphene.

  15. Sputtering of metals at ion-electron irradiation

    NASA Astrophysics Data System (ADS)

    Martynenko, Yu. V.; Korshunov, S. N.; Skorlupkin, I. D.

    2014-02-01

    It has been found that, in contrast to the commonly accepted opinion, simultaneous irradiation by 15-keV Ar+ ions and 2.5-keV electrons at temperatures above 0.5 T m ( T m is the melting temperature) induces much larger sputtering of metallic copper, nickel, and steel than irradiation only by Ar+ ions. The effect increases with the temperature. At T = 0.7 T m, the sputtering coefficients in the case of ion-electron irradiation are more than twice as large as the sputtering coefficients in the case of irradiation by Ar+ ions. The experiments on the sublimation of copper show that the sublimation rate in the case of the heating of a sample by an electron beam is higher than that in the case of heating in an electric vacuum oven. The revealed effects are explained by the electron-induced excitation of adatoms (atoms stuck over the surface, which appear owing to ion bombardment). Excited adatoms have a smaller binding energy with the surface and are sputtered more easily.

  16. Structure alterations in microporous (Mg,Fe) 2Al 4Si 5O 18 crystals induced by energetic heavy-ion irradiation

    NASA Astrophysics Data System (ADS)

    Miletich, Ronald; Diego Gatta, G.; Redhammer, Günther J.; Burchard, Michael; Meyer, Hans-Peter; Weikusat, Christian; Rotiroti, Nicola; Glasmacher, Ulrich A.; Trautmann, Christina; Neumann, Reinhard

    2010-10-01

    The microporous framework structure of (Mg 1- xFe x) 2Al 4Si 5O 18 (=cordierite) has been subject to a comparative study on the effect of structural alterations originating from exposure to high-energy heavy ions. Oriented samples (with x=0.061, 0.122, and 0.170) were irradiated with swift 124Xe, 197Au and 96Ru ions with 11.1 MeV per nucleon energy and fluences of 1×10 12 and 1×10 13 ions/cm 2. Irradiated and non-irradiated samples were investigated by means of X-ray diffraction, Mössbauer spectroscopy and optical absorption spectroscopy. Structural investigations reveal an essentially unchanged Al,Si ordering, which appears to be unaffected by irradiation. The most remarkable macroscopic change is the ion-beam induced colouration, which could be assigned to electronic charge transfer transitions involving the Fe cations. Mössbauer spectra indicate an increased amount of [4]Fe 3+ for the irradiated sample. The most noticeable structural alteration concerns irradiation-induced dehydration of extra-framework H 2O, which is accompanied by a reduction in the molar volume by ˜0.2 vol%.

  17. Ion beam irradiation of Langmuir--Blodgett polydiacetylene films

    SciTech Connect

    Elman, B.S.; Blackburn, G.F.; Samuelson, L.A.; Kenneson, D.G.

    1986-09-08

    Effects of ion beam irradiation of approx. =100-nm-thick Langmuir--Blodgett polydiacetylene films have been investigated in the low-energy regime E-italic<200 keV. Optical absorption and electrical resistivity measurements have been performed to characterize the modified materials. The results show that changes in optical and electrical properties associated with structural modifications are strongly correlated.

  18. Effects of Ga ion-beam irradiation on monolayer graphene

    SciTech Connect

    Wang, Quan; Mao, Wei; Zhang, Yanmin; Shao, Ying; Ren, Naifei; Ge, Daohan; State Key Laboratory of Transducer Technology, Chinese Academy of Sciences, Shanghai 200050

    2013-08-12

    The effects of Ga ion on the single layer graphene (SLG) have been studied by Raman spectroscopy (RS), SEM, and field-effect characterization. Under vacuum conditions, Ga ion-irradiation can induce disorders and cause red shift of 2D band of RS, rather than lattice damage in high quality SLG. The compressive strain induced by Ga ion decreases the crystalline size in SLG, which is responsible for the variation of Raman scattering and electrical properties. Nonlinear out-put characteristic and resistance increased are also found in the I-V measurement. The results have important implications during CVD graphene characterization and related device fabrication.

  19. Ion irradiation effects on the exchange bias in IrMn/Co films

    SciTech Connect

    Schafer, D.; Grande, P. L.; Pereira, L. G.; Geshev, J.

    2011-01-15

    The present work reports on the influence of ion irradiation in exchange-coupled bilayers. Magnetron-sputtered IrMn{sub 4}/Co films were irradiated with 40 keV He{sup +} ions and the dependence of their magnetic properties was studied as function of ion fluence and current used during the irradiations. The effects of ion damage and electronic excitation were also studied through additional irradiations with H{sup +} and Ne{sup +} ions. The results show a clear dependence of the exchange-bias field on the defects caused by the ion bombardment. No correlations with other irradiation effects were observed.

  20. Ion Irradiation Effects in Synthetic Garnets Incorporating Actinides Satoshi Utsunomiya1

    E-print Network

    Utsunomiya, Satoshi

    Ion Irradiation Effects in Synthetic Garnets Incorporating Actinides Satoshi Utsunomiya1 , Lu the long term radiation effects due to radioactive decay can be simulated in short term with heavy ion-irradiation[3], many irradiation experiments using heavy ions have been completed in the potential ceramics

  1. Effects on focused ion beam irradiation on MOS transistors

    SciTech Connect

    Campbell, A.N.; Peterson, K.A.; Fleetwood, D.M.; Soden, J.M.

    1997-04-01

    The effects of irradiation from a focused ion beam (FIB) system on MOS transistors are reported systematically for the first time. Three MOS transistor technologies, with 0.5, 1, and 3 {mu}m minimum feature sizes and with gate oxide thicknesses ranging from 11 to 50 nm, were analyzed. Significant shifts in transistor parameters (such as threshold voltage, transconductance, and mobility) were observed following irradiation with a 30 keV Ga{sup +} focused ion beam with ion doses varying by over 5 orders of magnitude. The apparent damage mechanism (which involved the creation of interface traps, oxide trapped charge, or both) and extent of damage were different for each of the three technologies investigated.

  2. Ion emission from fused silica under 157-nm irradiation

    NASA Astrophysics Data System (ADS)

    John, Sharon R.; Leraas, J. A.; Langford, S. C.; Dickinson, J. T.

    2007-04-01

    We present a summary of initial work on the etching of silica at 157 nm. At fluences well below the threshold for plasma formation, we have characterized the direct desorption of atomic ions from fused silica surfaces during 157-nm irradiation. The ion identities and kinetic energies were determined by time-resolved mass spectroscopy. The principal ions are Si+ and O+. The emission intensities are dramatically increased by treatments that are expected to increase the density of surfaces defects. Molecular dynamics simulations of the silica surface suggest that silicon ions bound at surface oxygen vacancies (analogous to E' centers) provide suitable configurations for emission. We propose that emission is best understood in terms of a hybrid mechanism involving both antibonding chemical forces (Menzel-Gomer-Redhead model) and repulsive electrostatic forces on the adsorbed ion after laser excitation of the underlying defect.

  3. In-situ high temperature irradiation setup for temperature dependent structural studies of materials under swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Kulriya, P. K.; Kumari, Renu; Kumar, Rajesh; Grover, V.; Shukla, R.; Tyagi, A. K.; Avasthi, D. K.

    2015-01-01

    An in-situ high temperature (1000 K) setup is designed and installed in the materials science beam line of superconducting linear accelerator at the Inter-University Accelerator Centre (IUAC) for temperature dependent ion irradiation studies on the materials exposed with swift heavy ion (SHI) irradiation. The Gd2Ti2O7 pyrochlore is irradiated using 120 MeV Au ion at 1000 K using the high temperature irradiation facility and characterized by ex-situ X-ray diffraction (XRD). Another set of Gd2Ti2O7 samples are irradiated with the same ion beam parameter at 300 K and simultaneously characterized using in-situ XRD available in same beam line. The XRD studies along with the Raman spectroscopic investigations reveal that the structural modification induced by the ion irradiation is strongly dependent on the temperature of the sample. The Gd2Ti2O7 is readily amorphized at an ion fluence 6 × 1012 ions/cm2 on irradiation at 300 K, whereas it is transformed to a radiation-resistant anion-deficient fluorite structure on high temperature irradiation, that amorphized at ion fluence higher than 1 × 1013 ions/cm2. The temperature dependent ion irradiation studies showed that the ion fluence required to cause amorphization at 1000 K irradiation is significantly higher than that required at room temperature irradiation. In addition to testing the efficiency of the in-situ high temperature irradiation facility, the present study establishes that the radiation stability of the pyrochlore is enhanced at higher temperatures.

  4. Ion beam irradiated optical channel waveguides

    NASA Astrophysics Data System (ADS)

    Bányász, I.; Rajta, I.; Nagy, G. U. L.; Zolnai, Z.; Havranek, V.; Pelli, S.; Veres, M.; Himics, L.; Berneschi, S.; Nunzi-Conti, G.; Righini, G. C.

    2014-03-01

    Nowadays, in the modern optical communications systems, channel waveguides represent the core of many active and passive integrated devices, such as amplifiers, lasers, couplers and splitters. Different materials and fabrication processes were investigated in order to achieve the aforementioned optoelectronic circuits with low costs and high performance and reproducibility. Nevertheless, the 2D guiding structures fabrication continues to be a challenging task in some of optical materials due to their susceptibility to mechanical and/or chemical damages which can occur during the different steps of the fabrication process. Here we report on channel waveguides demonstration in erbium doped Tungsten - Tellurite (Er3+:TeO2-WO3) glasses and BGO crystals by means of a masked ion beam and/or direct writing processes performed at different energy MeV and ions species. The evidence of the waveguides formation was investigated by microscopy techniques and micro Raman spectroscopy.

  5. Comparison of Deuterium Retention for Ion-irradiated and Neutron-irradiated Tungsten

    SciTech Connect

    Yasuhisa Oya; Masashi Shimada; Makoto Kobayashi; Takuji Oda; Masanori Hara; Hideo Watanabe; Yuji Hatano; Pattrick Calderoni; Kenji Okuno

    2011-12-01

    The behavior of D retention for Fe{sup 2+}-irradiated tungsten with a damage of 0.025-3 dpa was compared with that for neutron-irradiated tungsten with 0.025 dpa. The D{sub 2} thermal desorption spectroscopy (TDS) spectra for Fe{sup 2+}-irradiated tungsten consisted of two desorption stages at 450 and 550 K, while that for neutron-irradiated tungsten was composed of three stages and an addition desorption stage was found at 750 K. The desorption rate of the major desorption stage at 550K increased as the displacement damage increased due to Fe{sup 2+} irradiation increasing. In addition, the first desorption stage at 450K was found only for damaged samples. Therefore, the second stage would be based on intrinsic defects or vacancy produced by Fe{sup 2+} irradiation, and the first stage should be the accumulation of D in mono-vacancy and the activation energy would be relatively reduced, where the dislocation loop and vacancy is produced. The third one was found only for neutron irradiation, showing the D trapping by a void or vacancy cluster, and the diffusion effect is also contributed to by the high full-width at half-maximum of the TDS spectrum. Therefore, it can be said that the D{sub 2} TDS spectra for Fe{sup 2+}-irradiated tungsten cannot represent that for the neutron-irradiated one, indicating that the deuterium trapping and desorption mechanism for neutron-irradiated tungsten is different from that for the ion-irradiated one.

  6. Improvement of Specimen Preparation Process for Bulge Test Using the Combination of XeF2 and Deep Reactive Ion Etching

    NASA Astrophysics Data System (ADS)

    Wu, Chung-Lin; Yip, Ming-Chuen; Fang, Weileun

    2009-06-01

    The bulge test is a convenient approach to determine the thin film mechanical properties. This study presents a fabrication process to prepare the circular membrane made of metal as well as dielectric films for bulge test. The process successfully combines the dry etching of deep reactive ion etching (DRIE) and XeF2 to release the test metal films. The Si3N4 film is used to protect the metal layers during the release process. Thus, the ion bombardment of the test metal films by DRIE is prevented. In addition, this process is also designed to prevent the pre-deformation of the Si3N4 and the metal films before release. By changing the recipe of XeF2 etching, the circular Si3N4 test membrane can also be fabricated. In applications, the circular membranes of Al, Au, and Si3N4 films were successfully prepared using the presented approach. This study also performed the bulge test by using these specimens to determine the thin film elastic modulus.

  7. Kr Ion Irradiation Study of the Depleted-Uranium Alloys

    SciTech Connect

    J. Gan; D. Keiser; B. Miller; M. Kirk; J. Rest; T. Allen; D. Wachs

    2010-12-01

    Fuel development for the Reduced Enrichment Research and Test Reactor program is tasked with the development of new low-enriched uranium nuclear fuels that can be employed to replace existing highly enriched uranium fuels currently used in some research reactors throughout the world. For dispersion-type fuels, radiation stability of the fuel/cladding interaction product has a strong impact on fuel performance. Three depleted uranium alloys are cast for the radiation stability studies of the fuel/cladding interaction product using Kr ion irradiation to investigate radiation damage from fission products. SEM analysis indicates the presence of the phases of interest: U(Si, Al)3, (U, Mo)(Si, Al)3, UMo2Al20, U6Mo4Al43, and UAl4. Irradiations of TEM disc samples were conducted with 500 keV Kr ions at 200ºC to ion doses up to 2.5 × 1015 ions/cm2 (~ 10 dpa) with an Kr ion flux of 1012 ions/cm2-sec (~ 4.0 × 10-3 dpa/sec). Microstructural evolution of the phases relevant to fuel-cladding interaction products was investigated using transmission electron microscopy.

  8. Characterization of swift heavy ion irradiation damage in ceria

    SciTech Connect

    Yablinsky, Clarissa A.; Devanathan, Ram; Pakarinen, Janne; Gan, Jian; Severin, Daniel; Trautmann, Christina; Allen, Todd R.

    2015-03-04

    Swift heavy ion induced radiation damage is investigated for ceria (CeO2), which serves as a UO2 fuel surrogate. Microstructural changes resulting from an irradiation with 940 MeV gold ions of 42 keV/nm electronic energy loss are investigated by means of electron microscopy accompanied by electron energy loss spectroscopy showing that there exists a small density reduction in the ion track core. While chemical changes in the ion track are not precluded, evidence of them was not observed. Classical molecular dynamics simulations of thermal spikes in CeO2 with an energy deposition of 12 and 36 keV/nm show damage consisting of isolated point defects at 12 keV/nm, and defect clusters at 36 keV/nm, with no amorphization at either energy. Inferences are drawn from modeling about density changes in the ion track and the formation of interstitial loops that shed light on features observed by electron microscopy of swift heavy ion irradiated ceria.

  9. Magnetic properties of graphite irradiated with MeV ions

    SciTech Connect

    Ramos, M. A.; Munoz-Martin, A.; Climent-Font, A.; Barzola-Quiquia, J.; Esquinazi, P.; Garcia-Hernandez, M.

    2010-06-01

    We have studied the change in the magnetic properties produced on highly oriented pyrolytic graphite samples by irradiation of H, C, and N ions in the mega-electron-volt energy range. The use of specially made sample holders for the magnetic measurements provided high reproducibility allowing us to obtain directly the irradiation effects without any corrections or subtractions. Our results show that three magnetic phenomena are triggered by the defects produced by the irradiation, namely, Curie-type paramagnetism, ferromagnetism and an anomalous paramagnetic state that appears as precursor of the magnetic ordered state. Using SRIM simulations to estimate the amount of vacancies produced by the irradiation, the Curie-type paramagnetic response indicates an effective Bohr magneton number per nominally produced vacancy p=0.27+-0.02mu{sub B}. Direct measurements of the surface sample temperature during irradiation and the decrease in the (as-received) paramagnetic as well as ferromagnetic contributions after irradiation indicate that self-heating is one of the causes for small yield of ferromagnetism. Taking into account the hydrogen distribution in the virgin samples, the obtained results indicate that the induced ferromagnetism appears when the average vacancy distance is {approx}2 nm in the near surface region.

  10. Sputtering of amorphous silicon nitride irradiated with energetic C60 ions: Preferential sputtering and synergy effect between electronic and collisional sputtering

    NASA Astrophysics Data System (ADS)

    Kitayama, T.; Morita, Y.; Nakajima, K.; Narumi, K.; Saitoh, Y.; Matsuda, M.; Sataka, M.; Toulemonde, M.; Kimura, K.

    2015-12-01

    Amorphous silicon nitride films (thickness 30 nm) deposited on Si(0 0 1) were irradiated with 30-1080 keV C60 and 100 MeV Xe ions to fluences ranging from 2 × 1011 to 1 × 1014 ions/cm2. The composition depth profiles of the irradiated samples were measured using high-resolution Rutherford backscattering spectrometry. The sputtering yields were estimated from the derived composition profiles. Pronounced preferential sputtering of nitrogen was observed in the electronic energy loss regime. In addition, a large synergy effect between the electronic and collisional sputtering was also observed. The sputtering yields were calculated using the unified thermal spike model to understand the observed results. Although the calculated results reproduced the observed total sputtering yields with a lowered sublimation energy, the observed preferential sputtering of nitrogen could not be explained. The present results suggest an additional sputtering mechanism related to the electronic energy loss.

  11. Metastable hydronium ions in UV-irradiated ice

    SciTech Connect

    Moon, Eui-Seong; Kang, Heon

    2012-11-28

    We show that the irradiation of UV light (10-11 eV) onto an ice film produces metastable hydronium (H{sub 3}O{sup +}) ions in the ice at low temperatures (53-140 K). Evidence of the presence of metastable hydronium ions was obtained by experiments involving adsorption of methylamine onto UV-irradiated ice films and hydrogen-deuterium (H/D) isotopic exchange reaction. The methylamine adsorption experiments showed that photogenerated H{sub 3}O{sup +} species transferred a proton to the methylamine arriving at the ice surface, thus producing the methyl ammonium ion, which was detected by low energy sputtering method. The H{sub 3}O{sup +} species induced the H/D exchange of water, which was monitored through the detection of water isotopomers on the surface by using the Cs{sup +} reactive ion scattering method. Thermal and temporal stabilities of H{sub 3}O{sup +} and its proton migration activity were examined. The lifetime of the hydronium ions in the amorphized ice was greater than 1 h at {approx}53 K and decreased to {approx}5 min at 140 K. Interestingly, a small portion of hydronium ions survived for an extraordinarily long time in the ice, even at 140 K. The average migration distance of protons released from H{sub 3}O{sup +} in the ice was estimated to be about two water molecules at {approx}54 K and about six molecules at 100 K. These results indicate that UV-generated hydronium ions can be efficiently stabilized in low-temperature ice. Such metastable hydronium ions may play a significant role in the acid-base chemistry of ice particles in interstellar clouds.

  12. Mutagenic effects of heavy ion irradiation on rice seeds

    NASA Astrophysics Data System (ADS)

    Xu, Xue; Liu, Binmei; Zhang, Lili; Wu, Yuejin

    2012-11-01

    Three varieties of rice seeds were subjected to irradiation using low-energy and medium-energy ions. The damage and mutations induced by the ions were examined. In addition, genetic analysis and gene mapping of spotted leaf (spl) mutants were performed. Low-energy ions had no significant influence on germination, survival or seedling height, except for the survival of Nipponbare. Medium-energy ions had a significant influence on germination and survival but had no significant effect on seedling height. In the low-energy group, among 60,000 M2 plants, 2823 putative morphological mutants were found, and the mutation frequency was approximately 4.71%. In the medium-energy group, 3132 putative morphological mutants were found, and the mutation frequency was approximately 5.22%. Five spl mutants (spl29-spl33) were obtained by ion irradiation, and the heredity of the spl mutants was stable. The characteristics of the spl mutants were found, by genetic analysis and preliminary mapping, to be controlled by a single recessive gene, and spl30 and spl33 were found to be new lesion-mimic mutants.

  13. He ion irradiation damage to Al/Nb multilayers

    SciTech Connect

    Misra, Amit; Li, Nan; Martin, M S; Anderoglu, Osman; Shao, L; Wang, H; Zhang, X

    2009-01-01

    We investigated the evolution of microstructure and mechanical properties of sputter-deposited Al/Nb multilayers with individual layer thickness, h, of 1-200 nm, subjected to helium ion irradiations: 100 keV He{sup +} ions with a dose of 6 x 10{sup 16}/cm{sup 2}. Helium bubbles, 1-2 nm in diameter, were observed. When h is greater than 25 nm, hardnesses of irradiated multilayers barely change, whereas radiation hardening is more significant at smaller h. Transmission electron microscopy and scanning transmission electron microscopy studies reveal the formation of a thin layer of Nb{sub 3}Al intermetallic along the Al/Nb interface as a consequence of radiation induced intermixing. The dependence of radiation hardening on h is interpreted by using a composite model considering the formation of the hard Nb{sub 3}Al intermetallic layer.

  14. He ion irradiation damage in Al /Nb multilayers

    NASA Astrophysics Data System (ADS)

    Li, Nan; Martin, M. S.; Anderoglu, O.; Misra, A.; Shao, L.; Wang, H.; Zhang, X.

    2009-06-01

    We investigate the evolution of microstructure and mechanical properties of sputter-deposited Al /Nb multilayers with miscible fcc/bcc type interface and individual layer thickness, h, of 1-200nm, subjected to helium ion irradiations: 100keV He+ ions and a fluence of 6×1016/cm2. Helium bubbles, 1-2nm in diameter, are observed. When h is greater than 25nm, hardnesses of irradiated multilayers barely change, whereas radiation hardening is more significant at smaller h. Transmission electron microscopy and scanning transmission electron microscopy studies reveal the formation of a thin layer of Nb3Al intermetallic phase along the Al /Nb interface as a consequence of radiation induced intermixing. The dependence of radiation hardening on h is interpreted by using a composite model considering the formation of the hard Nb3Al intermetallic layer.

  15. Slowing down of fast electrons as probe for charging and decharging dynamics of ion-irradiated insulators

    SciTech Connect

    De Filippo, E.; Lanzano, G.; Amorini, F.; Geraci, E.; Grassi, L.; Politi, G.; La Guidara, E.; Lombardo, I.; Rizzo, F.; Russotto, P.; Volant, C.; Rothard, H.

    2011-06-15

    The slowing down of fast electrons emitted from insulators [Mylar, polypropylene (PP)] irradiated with swift ion beams (C, O, Kr, Ag, Xe; 20-64 MeV/u) was measured by the time-of-flight method at LNS, Catania and GANIL, Caen. The charge buildup, deduced from both convoy- and binary-encounter electron peak shifts, leads to target material-dependent potentials (6.0 kV for Mylar, 2.8 kV for PP). The number of projectiles needed for charging up (charging-up time constant) is inversely proportional to the electronic energy loss. After a certain time, a sudden decharging occurs. For low beam currents, charging-up time, energy shift corresponding to maximum charge buildup, and time of decharging are regular. For high beam currents, the time intervals become irregular (chaotic).

  16. Track Structure in DNA Irradiated with Heavy Ions

    SciTech Connect

    Bowman, Michael K.; Becker, David; Sevilla, Michael D.; Zimbrick, John D.

    2005-04-01

    The spatial properties of trapped radicals produced in heavy ion-irradiated solid DNA at 77 K have been probed using pulsed Electron Paramagnetic Double Resonance (PELDOR or DEER) techniques. Salmon testes DNA hydrated to twelve water molecules per nucleotide was irradiated with 40Ar ions of energy 100 MeV/nucleon and LET ranging from 300 to 400 keV/?. Irradiated samples were maintained at cryogenic temperature at all times. PELDOR measurements were made using a refocused echo detection sequence that allows dipolar interaction between trapped radicals to be observed. The EPR spectrum is attributed to electron loss/gain DNA base radicals and neutral carbon-centered radicals that likely arise from sugar damage. We find a radical concentration of 13.5*1018 cm-3 in the tracks and a track radius of 6.79 nm. The cross section of these tracks is 144 nm2 yielding a lineal radical density of 2.6 radicals/nm. Based upon the yields previously determined for particles having calculated LET values of 300-400 keV/mm and our measured lineal density, we obtain an LET of 270 keV/mm, which is in good agreement with the calculated range of values. These measurements of radical density and spatial extent provide the first direct experimental determination of track characteristics in irradiated DNA.

  17. Manipulation of the graphene surface potential by ion irradiation

    SciTech Connect

    Ochedowski, O.; Kleine Bussmann, B.; Schleberger, M.; Ban d'Etat, B.; Lebius, H.

    2013-04-15

    We show that the work function of exfoliated single layer graphene can be modified by irradiation with swift (E{sub kin}=92 MeV) heavy ions under glancing angles of incidence. Upon ion impact individual surface tracks are created in graphene on silicon carbide. Due to the very localized energy deposition characteristic for ions in this energy range, the surface area which is structurally altered is limited to Almost-Equal-To 0.01 {mu}m{sup 2} per track. Kelvin probe force microscopy reveals that those surface tracks consist of electronically modified material and that a few tracks suffice to shift the surface potential of the whole single layer flake by Almost-Equal-To 400 meV. Thus, the irradiation turns the initially n-doped graphene into p-doped graphene with a hole density of 8.5 Multiplication-Sign 10{sup 12} holes/cm{sup 2}. This doping effect persists even after heating the irradiated samples to 500 Degree-Sign C. Therefore, this charge transfer is not due to adsorbates but must instead be attributed to implanted atoms. The method presented here opens up a way to efficiently manipulate the charge carrier concentration of graphene.

  18. Effect of Ion Irradiation in Cadmium Niobate Pyrochlores

    SciTech Connect

    Jiang, Weilin; Weber, William J.; Thevuthasan, Suntharampillai; Boatner, Lynn A.

    2003-05-16

    Irradiation experiments have been performed for cadmium niobate pyrochlore (CdNb2O) single crystals at both 150 and 300 K using 1.0 MeV Au ions over fluences ranging from 0.01 to 0.10 ions/nm. In-situ 3.0 MeV He Rutherford backscattering spectrometry along the <100>-axial channeling direction (RBS/C) has been applied to study the damage states ranging from small defect concentrations to a fully amorphous state. Results show that the crystal can be readily amorphized under the irradiation conditions. Room-temperature recovery of the defects produced at 150 K has been observed, while the defects produced at 300 K are thermally stable at room temperature. Results also indicate that the RBS/C analysis used in this study induced negligible damage in the near-surface regime. In addition, irradiation at and below room temperature using He and C3 ions leads to surface exfoliation at the corresponding damage peaks.

  19. Structure alterations in microporous (Mg,Fe){sub 2}Al{sub 4}Si{sub 5}O{sub 18} crystals induced by energetic heavy-ion irradiation

    SciTech Connect

    Miletich, Ronald; Diego Gatta, G.; Redhammer, Guenther J.; Burchard, Michael; Meyer, Hans-Peter; Weikusat, Christian; Rotiroti, Nicola; Glasmacher, Ulrich A.; Trautmann, Christina; Neumann, Reinhard

    2010-10-15

    The microporous framework structure of (Mg{sub 1-x}Fe{sub x}){sub 2}Al{sub 4}Si{sub 5}O{sub 18} (=cordierite) has been subject to a comparative study on the effect of structural alterations originating from exposure to high-energy heavy ions. Oriented samples (with x=0.061, 0.122, and 0.170) were irradiated with swift {sup 124}Xe, {sup 197}Au and {sup 96}Ru ions with 11.1 MeV per nucleon energy and fluences of 1x10{sup 12} and 1x10{sup 13} ions/cm{sup 2}. Irradiated and non-irradiated samples were investigated by means of X-ray diffraction, Moessbauer spectroscopy and optical absorption spectroscopy. Structural investigations reveal an essentially unchanged Al,Si ordering, which appears to be unaffected by irradiation. The most remarkable macroscopic change is the ion-beam induced colouration, which could be assigned to electronic charge transfer transitions involving the Fe cations. Moessbauer spectra indicate an increased amount of {sup [4]}Fe{sup 3+} for the irradiated sample. The most noticeable structural alteration concerns irradiation-induced dehydration of extra-framework H{sub 2}O, which is accompanied by a reduction in the molar volume by {approx}0.2 vol%. - Graphical abstract: Cordierite single-crystal specimen showing the color change from pale blue (unirradiated) to a yellowish brown layer (irradiated) after exposure to relativistic {sup 124}Xe ions at a fluence of 1x10{sup 12} ions per cm{sup 2}.

  20. Synthesis of embedded Au nanostructures by ion irradiation: influence of ion induced viscous flow and sputtering.

    PubMed

    Singh, Udai B; Agarwal, D C; Khan, S A; Mohapatra, S; Amekura, H; Datta, D P; Kumar, Ajay; Choudhury, R K; Chan, T K; Osipowicz, Thomas; Avasthi, D K

    2014-01-01

    The ion-irradiation induced synthesis of embedded Au nanoparticles (NPs) into glass from islands of Au on a glass substrate is studied in the context of recoiling atoms, sputtering and viscous flow. Cross sectional transmission electron microscopy studies revealed the formation of Au NPs embedded in the glass substrates by the 50 keV Si(-) ion irradiation of irregularly shaped Au nanostructures on the glass surfaces at a fluence of 3 × 10(16) ions/cm(2). The depth profiles of Au in the samples were obtained from high-resolution Rutherford backscattering spectrometry studies. The results from TRIDYN simulation reveal the role of various ion-induced processes during the synthesis of the embedded Au NPs, viz. sputtering and recoiling atoms. Simulation and experimental results suggest that the viscous flow is one of the major factors that are responsible for the embedding of Au nanoparticles into the glass substrate. PMID:24605276

  1. Light ion irradiation for unfavorable soft tissue sarcoma

    SciTech Connect

    Linstadt, D.; Castro, J.R.; Phillips, T.L.; Petti, P.L.; Collier, J.M.; Daftari, I.; Schoethaler, R.; Rayner, A.

    1990-09-01

    Between 1978 and 1989, 32 patients with unfavorable soft tissue sarcoma underwent light ion (helium, neon) irradiation with curative intent at Lawrence Berkeley Laboratory. The tumors were located in the trunk in 22 patients and head and neck in 10. Macroscopic tumor was present in 22 at the time of irradiation. Two patients had tumors apparently induced by previous therapeutic irradiation. Follow-up times for surviving patients ranged from 4 to 121 months (median 27 months). The overall 3-year actuarial local control rate was 62%; the corresponding survival rate was 50%. The 3-year actuarial control rate for patients irradiated with macroscopic tumors was 48%, while none of the patients with microscopic disease developed local recurrence (100%). The corresponding 3-year actuarial survival rates were 40% (macroscopic) and 78% (microscopic). Patients with retroperitoneal sarcoma did notably well; the local control rate and survival rate were 64% and 62%, respectively. Complications were acceptable; there were no radiation related deaths, while two patients (6%) required operations to correct significant radiation-related injuries. These results appear promising compared to those achieved by low -LET irradiation, and suggest that this technique merits further investigation.

  2. Origins of ion irradiation-induced Ga nanoparticle motion on GaAs surfaces

    SciTech Connect

    Kang, M.; Wu, J. H.; Chen, H. Y.; Thornton, K.; Goldman, R. S.; Sofferman, D. L.; Department of Physics, Adelphi University, Garden City, New York 11530-0701 ; Beskin, I.

    2013-08-12

    We have examined the origins of ion irradiation-induced nanoparticle (NP) motion. Focused-ion-beam irradiation of GaAs surfaces induces random walks of Ga NPs, which are biased in the direction opposite to that of ion beam scanning. Although the instantaneous NP velocities are constant, the NP drift velocities are dependent on the off-normal irradiation angle, likely due to a difference in surface non-stoichiometry induced by the irradiation angle dependence of the sputtering yield. It is hypothesized that the random walks are initiated by ion irradiation-induced thermal fluctuations, with biasing driven by anisotropic mass transport.

  3. Characterization of polymeric films subjected to lithium ion beam irradiation

    SciTech Connect

    Gary S. Groenewold; W. Roger Cannon; Paul A. Lessing; Recep Avci; Muhammedin Deliorman; Mark Wolfenden; Doug W. Akers; J. Keith Jewell

    2013-02-01

    Two different polymeric materials that are candidate materials for use as binders for mixed uranium–plutonium oxide nuclear fuel pellets were subjected to Li ion beam irradiation, in order to simulate intense alpha irradiation. The materials (a polyethylene glycol 8000 and a microcrystalline wax) were then analyzed using a combination of mass spectrometry (MS) approaches and X-ray photoelectron spectroscopy (XPS). Samples of the irradiated PEG materials were dissolved in H2O and then analyzed using electrospray ionization-MS, which showed the formation of a series of small oligomers in addition to intact large PEG oligomers. The small oligomers were likely formed by radiation-induced homolytic scissions of the C–O and C–C bonds, which furnish radical intermediates that react by radical recombination with Hradical dot and OHradical dot. Surface analysis using SIMS revealed a heterogeneous surface that contained not only PEG-derived polymers, but also hydrocarbon-based entities that are likely surface contaminants. XPS of the irradiated PEG samples indicated the emergence of different carbon species, with peak shifts suggesting the presence of sp2 carbon atoms. Analysis of the paraffinic film using XPS showed the emergence of oxygen on the surface of the sample, and also a broadening and shifting of the C1s peak, demonstrating a change in the chemistry on the surface. The paraffinic film did not dissolve in either H2O or a H2O–methanol solution, and hence the bulk of the material could not be analyzed using electrospray. However a series of oligomers was leached from the bulk material that produced ion series in the ESI-MS analyses that were identified octylphenyl ethoxylate oligomers. Upon Li ion bombardment, these shifted to a lower average molecular weight, but more importantly showed the emergence of three new ion series that are being formed as a result of radiation damage. Surface analysis of the paraffinic polymers using SIMS produced spectra that were wholly dominated by hydrocarbon ion series, and no difference was observed between unirradiated and irradiated samples. The studies demonstrate that for the PEG-based polymers, direct evidence for radiolytic scission can be observed using ESI-MS, and suggests that both radiolytic pathways and efficiencies as a function of dose should be measurable by calibrating instrument response to the small oligomeric degradation products.

  4. Characterization of polymeric films subjected to lithium ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Groenewold, Gary S.; Cannon, W. Roger; Lessing, Paul A.; Avci, Recep; Deliorman, Muhammedin; Wolfenden, Mark; Akers, Doug W.; Jewell, J. Keith; Zuck, Larry D.

    2013-02-01

    Two different polymeric materials that are candidate materials for use as binders for mixed uranium-plutonium oxide nuclear fuel pellets were subjected to Li ion beam irradiation, in order to simulate intense alpha irradiation. The materials (a polyethylene glycol 8000 and a microcrystalline wax) were then analyzed using a combination of mass spectrometry (MS) approaches and X-ray photoelectron spectroscopy (XPS). Samples of the irradiated PEG materials were dissolved in H2O and then analyzed using electrospray ionization-MS, which showed the formation of a series of small oligomers in addition to intact large PEG oligomers. The small oligomers were likely formed by radiation-induced homolytic scissions of the C-O and C-C bonds, which furnish radical intermediates that react by radical recombination with Hrad and OHrad . Surface analysis using SIMS revealed a heterogeneous surface that contained not only PEG-derived polymers, but also hydrocarbon-based entities that are likely surface contaminants. XPS of the irradiated PEG samples indicated the emergence of different carbon species, with peak shifts suggesting the presence of sp2 carbon atoms. Analysis of the paraffinic film using XPS showed the emergence of oxygen on the surface of the sample, and also a broadening and shifting of the C1s peak, demonstrating a change in the chemistry on the surface. The paraffinic film did not dissolve in either H2O or a H2O-methanol solution, and hence the bulk of the material could not be analyzed using electrospray. However a series of oligomers was leached from the bulk material that produced ion series in the ESI-MS analyses that were identified octylphenyl ethoxylate oligomers. Upon Li ion bombardment, these shifted to a lower average molecular weight, but more importantly showed the emergence of three new ion series that are being formed as a result of radiation damage. Surface analysis of the paraffinic polymers using SIMS produced spectra that were wholly dominated by hydrocarbon ion series, and no difference was observed between unirradiated and irradiated samples. The studies demonstrate that for the PEG-based polymers, direct evidence for radiolytic scission can be observed using ESI-MS, and suggests that both radiolytic pathways and efficiencies as a function of dose should be measurable by calibrating instrument response to the small oligomeric degradation products.

  5. Ion irradiation damage in ilmenite at 100 K

    USGS Publications Warehouse

    Mitchell, J.N.; Yu, N.; Devanathan, R.; Sickafus, K.E.; Nastasi, M.A.; Nord, G.L., Jr.

    1997-01-01

    A natural single crystal of ilmenite (FeTiO3) was irradiated at 100 K with 200 keV Ar2+. Rutherford backscattering spectroscopy and ion channeling with 2 MeV He+ ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 ?? 1015 Ar2+/cm2, considerable near-surface He+ ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 nm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO3) and spinel (MgAl2O4) to explore factors that may influence radiation damage response in oxides.

  6. Investigations of heavy ion irradiation of gallium nitride nanowires and nanocircuits

    E-print Network

    Ayres, Virginia

    Investigations of heavy ion irradiation of gallium nitride nanowires and nanocircuits V.M. Ayres a online 7 February 2006 Abstract Results of a first investigation of the response of gallium nitride nanowires to high-Z heavy ion irradiation are reported. Pre-irradiation characterization of the gallium

  7. Shrinkage effects of polyimide film under ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Xu, X. L.; Yuehui, Yu; Zixin, Lin; Lizhi, Chen; Fang, Fang; Zuyao, Zhou; Shichang, Zou; Gendi, Du; Guanqun, Xia

    1991-07-01

    Ion beam induced electrical conduction of ion implanted polyimide film could find potential applications for encapsulation of microelectronic devices and gate-transistor fabrication. One of the important problems to be solved is the shrinkage effect of polyimide film under ion beam irradiation. In this work the shrinkage effects of B +-implanted polyimide film under different implantation conditions were investigated by using different techniques (IR reflection interference spectra, surface profile measuring system, and automatic spreading resistance measurements). According to the previous results of ASR measurement a multilayer model of the implanted polyimide film was proposed for the computer simulation of infrared reflection interference spectra. The shrinkage and depth profile of the refraction index of the implanted polyimide films will be discussed.

  8. Study of ion-irradiated tungsten in deuterium plasma

    NASA Astrophysics Data System (ADS)

    Khripunov, B. I.; Gureev, V. M.; Koidan, V. S.; Kornienko, S. N.; Latushkin, S. T.; Petrov, V. B.; Ryazanov, A. I.; Semenov, E. V.; Stolyarova, V. G.; Danelyan, L. S.; Kulikauskas, V. S.; Zatekin, V. V.; Unezhev, V. N.

    2013-07-01

    Experimental study aimed at investigation of neutron induced damage influence on fusion reactor plasma facing materials is reported. Displacement damage was produced in tungsten by high-energy helium and carbon ions at 3-10 MeV. The reached level of displacement damage ranged from several dpa to 600 dpa. The properties of the irradiated tungsten were studied in steady-state deuterium plasma on the LENTA linear divertor simulator. Plasma exposures were made at 250 eV of ion energy to fluence 1021-1022 ion/?m2. Erosion dynamics of the damaged layer and deuterium retention were observed. Surface microstructure modifications and important damage of the 5 ?m layer shown. Deuterium retention in helium-damaged tungsten (ERD) showed its complex behavior (increase or decrease) depending on implanted helium quantity and the structure of the surface layer.

  9. Swift heavy ion irradiation of Pt nanocrystals: I. shape transformation and dissolution

    SciTech Connect

    Giulian, R.; Araujo, L.L.; Kluth, P.; Sprouster, D.J.; Schnohr, C.S.; Byrne, A.P.; Ridgway, M.C.

    2014-09-24

    We report on the effects of swift heavy ion irradiation of embedded Pt nanocrystals (NCs), which change from spheres to prolate spheroids to rods upon irradiation. Using a broad range of ion irradiation energies and NC mean sizes we demonstrate that the elongation and dissolution processes are energy and size dependent, attaining comparable levels of shape transformation and dissolution upon a given energy density deposited in the matrix. The NC shape transformation remains operative despite discontinuous ion tracks in the matrix and exhibits a constant threshold size for elongation. In contrast, for ion irradiations in which the ion tracks are continuous, the threshold size for elongation is clearly energy dependent.

  10. Observation of K-shell resonances in Xe and XeF2

    NASA Astrophysics Data System (ADS)

    Southworth, Steve; Dunford, Robert; Ray, Dipanwita; Kanter, Elliot; Krässig, Bertold; Young, Linda; Walko, Don

    2013-05-01

    We recently reported on the ion charge states and fragmentation channels of Xe and XeF2 following K-shell x-ray absorption by the Xe atom. The ion spectra reveal effects of resonant excitations despite the 11.49-eV lifetime width of the vacancy states. Due to the high electronegativity of the F ligands, Xe forms stable molecules such as XeF2. With 10 valence electrons, XeF2 is a prime example of a hypervalent molecule and its structure has attracted interest since its discovery in the 1960s. A strong pre-edge resonance is observed in the x-ray absorption spectrum that we attribute to the antibonding 7?u orbital. Excitation of the 7?u resonance selects a spatially aligned ensemble of molecules as observed in our ion fragmentation spectra. Analysis of the x-ray absorption spectrum also yields a measurement of the chemical shift of the Xe 1s ionization energy resulting from the F ligands. Results of new measurements on Xe and XeF2 with an improved x-ray/ion coincidence instrument will also be reported. This work was supported by the Chemical Sciences, Geosciences, and Biosciences Division and the Advanced Photon Source by the Office of Basic Energy Sciences, Office of Science, US Dept of Energy, Contract DE-AC02-06CH11357.

  11. Heavy ion irradiation effects of brannerite-type ceramics

    NASA Astrophysics Data System (ADS)

    Lian, J.; Wang, L. M.; Lumpkin, G. R.; Ewing, R. C.

    2002-05-01

    Brannerite, UTi 2O 6, occurs in polyphase Ti-based, crystalline ceramics that are under development for plutonium immobilization. In order to investigate radiation effects caused by ?-decay events of Pu, a 1 MeV Kr + irradiation on UTi 2O 6, ThTi 2O 6, CeTi 2O 6 and a more complex material, composed of Ca-containing brannerite and pyrochlore, was performed over a temperature range of 25-1020 K. The ion irradiation-induced crystalline-to-amorphous transformation was observed in all brannerite samples. The critical amorphization temperatures of the different brannerite compositions are: 970 K, UTi 2O 6; 990 K, ThTi 2O 6; 1020 K, CeTi 2O 6. The systematic increase in radiation resistance from Ce-, Th- to U-brannerite is related to the difference of mean atomic mass of A-site cation in the structure. As compared with the pyrochlore structure-type, brannerite phases are more susceptible to ion irradiation-induced amorphization. The effects of structure and chemical compositions on radiation resistance of brannerite-type and pyrochlore-type ceramics are discussed.

  12. Ion irradiation-induced amorphization and nano-crystal formation in garnets

    E-print Network

    Utsunomiya, Satoshi

    Ion irradiation-induced amorphization and nano-crystal formation in garnets S. Utsunomiya a , L ion irradiation of the G3 garnet at a temperature of 1023 K near the Tc, nano-crystals were produced, particularly yttrium aluminum garnet (YAG), Y3Al5O12, and YAG doped by other ions for use in laser systems

  13. Defect recovery and damage reduction in borosilicate glasses under double ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Mir, A. H.; Peuget, S.; Toulemonde, M.; Bulot, P.; Jegou, C.; Miro, S.; Bouffard, S.

    2015-11-01

    A sodium borosilicate glass was irradiated sequentially and simultaneously with alpha particles and gold ions. Alpha particles induced partial recovery of the network damage and mechanical properties in the gold pre-irradiated glass, while no such recovery effect was observed during gold irradiation of the alpha pre-irradiated glass. The damage capacity of the gold ions was significantly reduced during simultaneous irradiation with alpha particles and gold ions. These results highlight that the irradiation sequence of the ions plays an important role in controlling the final damage level; and if properly employed, irradiation can be employed to induce defect recovery. Such results are of paramount importance to understand the radiation damage in nuclear reactor components and in nuclear waste glass matrices which are subjected to multiple particle irradiations.

  14. Systematic Ion Irradiation Experiments to Olivine: Comparison with Space Weathered Rims of Itokawa Regolith Particles

    NASA Astrophysics Data System (ADS)

    Matsumoto, T.; Tsuchiyama, A.; Watanabe, N.; Yasuda, K.; Miyake, A.; Nakauchi, Y.; Okada, T.; Abe, M.; Yada, T.; Uesugi, M.; Karouji, Y.; Nakato, A.; Hashiguschi, M.; Kumagai, K.

    2015-11-01

    We performed H and He ion irradiation experiments using olivine fragments, in order to reveal formation time-scales of space weathered rims and formation processes of blisters by solar wind irradiation.

  15. Dose response of alanine detectors irradiated with carbon ion beams

    SciTech Connect

    Herrmann, Rochus; Jaekel, Oliver; Palmans, Hugo; Sharpe, Peter; Bassler, Niels

    2011-04-15

    Purpose: The dose response of the alanine detector shows a dependence on particle energy and type when irradiated with ion beams. The purpose of this study is to investigate the response behavior of the alanine detector in clinical carbon ion beams and compare the results to model predictions. Methods: Alanine detectors have been irradiated with carbon ions with an energy range of 89-400 MeV/u. The relative effectiveness of alanine has been measured in this regime. Pristine and spread out Bragg peak depth-dose curves have been measured with alanine dosimeters. The track structure based alanine response model developed by Hansen and Olsen has been implemented in the Monte Carlo code FLUKA and calculations were compared to experimental results. Results: Calculations of the relative effectiveness deviate less than 5% from the measured values for monoenergetic beams. Measured depth-dose curves deviate from predictions in the peak region, most pronounced at the distal edge of the peak. Conclusions: The used model and its implementation show a good overall agreement for quasimonoenergetic measurements. Deviations in depth-dose measurements are mainly attributed to uncertainties of the detector geometry implemented in the Monte Carlo simulations.

  16. Carbon Nanomaterials Under Highly Energetic Heavy Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Callahan, J. M.; Jacobs, B. W.; McElroy, K.; Crimp, M. A.; Ronningen, R. M.; Zeller, A. F.; Shaw, H. C.

    2009-03-01

    The radiation performance of carbon nanomaterials: carbon onions and single-walled carbon nanotubes under highly energetic heavy ion irradiation was investigated, with highly oriented pyrolytic graphite (HOPG) used as the control. Samples were irradiated with a krypton-86 beam at 142 MeV/nucleon, a krypton-78 beam at 140 MeV/nucleon, and a calcium-48 beam at 140 MeV/nucleon and 70 MeV/nucleon at the National Superconducting Cyclotron Laboratory at Michigan State University. Fundamental structural and chemical modifications were investigated using Micro Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM). Results indicated that the radiation resiliency of the single-walled carbon nanotubes exceeded that of highly oriented pyrolytic graphite, while the carbon onions showed structural modifications of the outer onion layers in the form of faceting and onion fusion.

  17. Radiation stability of iron nanoparticles irradiated with accelerated iron ions

    NASA Astrophysics Data System (ADS)

    Uglov, V. V.; Remnev, G. E.; Kvasov, N. T.; Safronov, I. V.; Shymanski, V. I.

    2015-07-01

    In the present work the dynamic processes occurring in a nanoscale iron particle exposed to irradiation with iron ions of different energies are studied in detailed. It is shown that the elastic and thermoelastic crystal lattice responses to irradiation form force factors affecting the evolution of defect-impurity system, which, in turn, leads to a decrease in the number of structural defects. Quantitative estimations of the spatial distribution of defects resulting in their migration to the surface were obtained. Such self-organization of nanoparticles exposed to ionizing radiation can be used as a basis for the production of radiation-resistant nanostructured materials capable of sustaining a long-term radiation influence.

  18. Inner-shell photoionization and core-hole decay of Xe and XeF$_2$

    E-print Network

    Southworth, Stephen H; Picón, Antonio; Lehmann, C Stefan; Cheng, Lan; Stanton, John F

    2015-01-01

    Photoionization cross sections and partial ion yields of Xe and XeF$_2$ from Xe 3d$_{5/2}$, Xe 3d$_{3/2}$, and F 1s subshells in the 660--740 eV range are compared to explore effects of the F ligands. The Xe 3d - $\\epsilon$f continuum shape resonances dominate the photoionization cross sections of both the atom and molecule, but prominent resonances appear in the XeF$_2$ cross section due to nominal excitation of Xe 3d and F 1s electrons to the lowest unoccupied molecular orbital (LUMO), a delocalized anti-bonding MO. The subshell ionization thresholds, the LUMO resonance energies and their oscillator strengths are calculated by relativistic coupled-cluster methods. Several charge states and fragment ions are produced from the atom and molecule due to alternative decay pathways from the inner-shell holes. Total and partial ion yields vary in response to the shape resonances and LUMO resonances. Previous calculations and measurements of atomic Xe 3d core-hole decay channels and our calculated results for XeF$_...

  19. The influence of carbon ion irradiation on sweet sorghum seeds

    NASA Astrophysics Data System (ADS)

    Dong, X. C.; Li, W. J.; Liu, Q. F.; He, J. Y.; Yu, L. X.; Zhou, L. B.; Qu, Y.; Xie, H. M.

    2008-01-01

    The aim of this study is to investigate the effects of different doses of 100 MeV/u carbon ions on sweet sorghum seeds in order to improve crop yields and their sugar content. After irradiation, seeds were germinated and grown to 30 days, and others were sown in the field. At the end of harvesting season all planted seeds were picked separately and M2 generations obtained. The differences among the treatments were examined using the RAPD procedure. In the study done by using 38 primers; according to the amplification results, the differences among the various doses treatment were shown.

  20. The change of microstructure and thermal properties in ion irradiated carbon nanotube mats as a function of ion penetration depth

    SciTech Connect

    Aitkaliyeva, A.; Shao, L.; Department of Nuclear Engineering, Texas A and M University, College Station, Texas 77843

    2013-02-11

    A stack of three carbon nanotube (CNT) mats was irradiated with 3 MeV He ions. The change in structural and thermal properties of individual mats as a function of ion penetration depth was characterized using electron microscopy and laser flash techniques. Ion irradiation can enhance thermal conductivity of the mats by introducing inter-tube displacements, which improve phonon transport across adjacent nanotubes. The enhancement, however, is reduced at higher damage levels due to the increasing phonon-defect scattering within the tubes. This study demonstrates the feasibility of using ion irradiation to manipulate thermal transport in carbon nanotubes.

  1. The change of microstructure and thermal properties in ion irradiated carbon nanotube mats as a function of ion penetration depth

    NASA Astrophysics Data System (ADS)

    Aitkaliyeva, A.; Shao, L.

    2013-02-01

    A stack of three carbon nanotube (CNT) mats was irradiated with 3 MeV He ions. The change in structural and thermal properties of individual mats as a function of ion penetration depth was characterized using electron microscopy and laser flash techniques. Ion irradiation can enhance thermal conductivity of the mats by introducing inter-tube displacements, which improve phonon transport across adjacent nanotubes. The enhancement, however, is reduced at higher damage levels due to the increasing phonon-defect scattering within the tubes. This study demonstrates the feasibility of using ion irradiation to manipulate thermal transport in carbon nanotubes.

  2. Uniform behavior of insulators irradiated by swift heavy ions

    NASA Astrophysics Data System (ADS)

    Szenes, G.

    2015-07-01

    Ion induced Re track radii are derived from a universal relation ?(r) without involving any materials parameter apart from the melting point Tm. The effect is related to the formation of identical ion-induced temperature distributions in track forming insulators for =Se / N = constant, where Se, and N are the electronic stopping power and the atomic density. Based on ?(r), an Re2 - / (Tm -Tir) plot is applied where the experimental curves coincide for various insulators without adjustable parameters (Tir - temperature of irradiation). The analysis extends to all track-forming insulators studied up until now. The application of the equilibrium value of Tm is justified in thermal spike calculations. The physical meaning of the condition =Se / N = constant is discussed. ?(r) may be valid in those insulators as well in which tracks are not induced. The Fourier equation is not valid under spike conditions.

  3. Ultrafast reconstruction of graphite by irradiating with highly charged ions

    SciTech Connect

    Miyamoto, Yoshiyuki

    2007-09-10

    Irradiating with highly charged Ar ions (Ar{sup 8+}) causes an unanticipated structural reconstruction of graphite [T. Meguro et al., Appl. Phys. Lett. 79, 3866 (2001)] with a particular incidence energy of 400 eV. To analyze this result, it is necessary to take into account charge transfer dynamics and ion dynamics simultaneously, which is not included in conventional first-principles scheme. An application of the time-dependent density functional theory coupled with molecular dynamics showed a variety of reconstructions (single vacancies, interlayer bridges, and sp{sup 3}-like bonds) depending on Ar{sup 8+} incidence energies and should stimulate further research over a wide range of the incident energies.

  4. Neovascular glaucoma after helium ion irradiation for uveal melanoma

    SciTech Connect

    Kim, M.K.; Char, D.H.; Castro, J.L.; Saunders, W.M.; Chen, G.T.; Stone, R.D.

    1986-02-01

    Neovascular glaucoma developed in 22 of 169 uveal melanoma patients treated with helium ion irradiation. Most patients had large melanomas; no eyes containing small melanomas developed anterior segment neovascularization. The mean onset of glaucoma was 14.1 months (range, 7-31 months). The incidence of anterior segment neovascularization increased with radiation dosage; there was an approximately three-fold increase at 80 GyE versus 60 GyE of helium ion radiation (23% vs. 8.5%) (P less than 0.05). Neovascular glaucoma occurred more commonly in larger tumors; the incidence was not affected by tumor location, presence of subretinal fluid, nor rate of tumor regression. Fifty-three percent of patients had some response with intraocular pressures of 21 mmHg or less to a combination of antiglaucoma treatments.

  5. Vacuum ultraviolet absorption and ion track effects in LiF crystals irradiated with swift ions

    NASA Astrophysics Data System (ADS)

    Davidson, A. T.; Schwartz, K.; Comins, J. D.; Kozakiewicz, A. G.; Toulemonde, M.; Trautmann, C.

    2002-12-01

    LiF crystals were irradiated with various light and heavy ions (Ni, Zn, Au, Pb, Bi, and U) of MeV to GeV energy. The radiation damage was studied by optical spectroscopy from the vacuum ultraviolet to the visible spectral region and by small angle x-ray scattering, in combination with optical bleaching and thermal annealing. In addition to the well-known electron centers (F and F2 centers) and the hole centers responsible for the previously observed band at 114 nm, a new absorption band was observed at 121 nm. The new band appears prominently in crystals irradiated with the heaviest projectiles (Au, Pb, Bi, U), is small for Zn ions, insignificant for the lighter Ni ion and absent in case of gamma irradiation. Under optical bleaching, F- and 114-nm centers are destroyed whereas the 121-nm band is relatively stable. The decay of the 121-nm band on thermal annealing coincides with the reduction of the small-angle x-ray scattering signal. It is considered that the 121-nm band is directly linked to hole-center clusters complementary to the electron-center aggregates in the core region of ion tracks. Evidence is presented to associate an absorption band at 275 nm formed after thermal annealing with the formation of small quasi-colloidal aggregates.

  6. TOPICAL REVIEW: Single-ion irradiation: physics, technology and applications

    NASA Astrophysics Data System (ADS)

    Ohdomari, Iwao

    2008-02-01

    Among the various radiation effects which involve the study of radiation environments, responses of materials and devices to radiation, radiation testing and radiation hardening of devices and equipment, this review mainly considers the radiation effects induced by alpha particles and other ions used in semiconductor technology on Si crystals and Si devices. We first describe the single-ion microprobe that enables the study of the site dependence of radiation hardness in a semiconductor device. Next, we describe single-ion implantation as a tool for suppressing fluctuation in device function induced by the discrete number and random position of dopant atoms. Finally, we describe the common features associated with both 'probing' and 'modification' in terms of the nature and behaviour of defect clusters induced by single-ion irradiation. A special feature of the review is that the radiation effects discussed here are induced by 'single' particles, and not by particle beams. Although there is a great amount of accumulated data on radiation effects, they are discussed in the conventional terms of 'dose' or 'fluence,' whose unit is cm-2. Therefore, this review provides complementary information on radiation effects.

  7. Translational energy dependence of reaction mechanism: Xe++CH4?XeH++CH3

    E-print Network

    Miller, G. D.; Strattan, L. W.; Cole, C. L.; Hierl, Peter M.

    1981-01-01

    The dynamics of the exoergic ion–molecule reaction Xe+(CH4,CH3)XeH+ were studied by chemical accelerator techniques over the relative translational energy range 0.2 to 8 eV. Results of the kinematicmeasurements are reported as scattering intensity...

  8. One and two-electron investigation of electronic structure for Ba(+)Xe and BaXe van der Waals molecules in a pseudopotential approach.

    PubMed

    Abdessalem, Kawther; Mejrissi, Leila; Issaoui, Noureddine; Oujia, Brahim; Gadéa, Florent Xavier

    2013-09-12

    The potential energy curves, vibrational energy levels, spectroscopic constants, and dipole moment curves for the ground and excited states of BaXe and its ion Ba(+)Xe molecules are calculated with an ab initio method using pseudopotential techniques and core polarization potentials. The molecules are treated as two (BaXe) or one (Ba(+)Xe) active electrons systems taking benefit of the zero pseudopotential approach for Xe. The vibrational levels and their energy spacing have been also determined for ?(+), ?, and ? states. The permanent and transition dipole moment curves are investigated for the (1,3)?(+) states of the BaXe neutral molecule and (2)?(+) states of the Ba(+)Xe ion. The analysis of these numerous results shows interesting behavior in potential energy curves imprinted by the strong repulsive interactions between electron and Xe and also indicates an intense transition dipole moment for both Ba(+)Xe and BaXe. PMID:23987477

  9. by swift heavy ion irradiation: anomalous photorefractive damage behavior

    NASA Astrophysics Data System (ADS)

    Jubera, M.; Garcia-Cabañes, A.; Carrascosa, M.; Olivares, J.

    2014-08-01

    Using swift heavy fluorine ion irradiation, we have successfully fabricated optical waveguides in Mg-doped LiNbO3 substrates. A systematic characterization of these structures has been carried out including refractive index profiles, propagation losses, nonlinear coefficients, and, specially, photorefractive optical damage. Step-like refractive index profiles with ?n e ? 0.1 and ?n o ? 0.2, propagation losses lower than 0.5 dB/cm and high nonlinear optical coefficients similar to those of the substrate have been obtained. Unexpectedly, the photorefractive damage is only moderately reduced with regard to the one presented in congruent LiNbO3 waveguides. Specifically, light intensity damage thresholds I th are only a factor 2 higher at RT and a factor 4 at 90 °C with regard to undoped waveguides. At this latter temperature, a remarkably high I th = 30.000 W/cm2 is reached. A final discussion on the observed anomalous optical damage behavior induced by swift heavy ion irradiation is also included.

  10. Reliability studies on NPN RF power transistors under swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Pushpa, N.; Praveen, K. C.; Gnana Prakash, A. P.; Naik, P. S.; Cressler, John D.; Gupta, S. K.; Revannasiddaiah, D.

    2012-02-01

    NPN RF power transistors were irradiated with 140 MeV Si 10+ ions, 100 MeV F 8+ ions, 50 MeV Li 3+ ions and Co-60 gamma radiation in the dose range from 100 krad to 100 Mrad. The transistor characteristics are studied before and after irradiation from which the parameters such as Gummel characteristics, excess base current (? IB = IBpost - IBpre), dc current gain ( hFE), transconductance ( gm) and collector-saturation current ( ICSat) are determined. The degradation observed in the electrical characteristics is almost the same for different types of ion irradiated NPN RF power transistors with similar total doses although there is a large difference in the linear energy transfer (LET) of the ions. Further, it was observed more degradation in DC I- V characteristics of ion irradiated devices than the Co-60 gamma irradiated devices for higher doses.

  11. Inner-shell photoionization and core-hole decay of Xe and XeF2

    NASA Astrophysics Data System (ADS)

    Southworth, Stephen; Picón, Antonio; Lehmann, C. Stefan; Wehlitz, Ralf; Cheng, Lan; Stanton, John F.

    2015-03-01

    Molecular effects on inner-shell photoionization and core-hole decay are explored by comparing cross sections and partial ion yields of Xe and XeF2 from Xe 3d and F 1s subshells in the 660-740 eV range. The Xe 3d- ?f continuum shape resonances dominate the total cross sections, but prominent resonances appear in the XeF2 cross section due to excitation of Xe 3d and F 1s electrons to the lowest unoccupied molecular orbital (LUMO), a delocalized anti-bonding MO. Relativistic coupled-cluster calculations were performed to identify the subshell ionization thresholds, the LUMO resonances and their oscillator strengths. Comparison of the Xe charge state distributions of the atom and molecule show a general shift to lower charge states in XeF2. The measurements support a model of core-hole decay in which charge is redistributed from Xe to the F ligands and energetic F ions are produced by Coulombic fragmentation. Supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, US Dept of Energy, Contract DE-AC02-06CH11357.

  12. Net sputtering rate due to hot ions in a Ne-Xe discharge gas bombarding an MgO layer

    SciTech Connect

    Ho, S.; Tamakoshi, T.; Ikeda, M.; Mikami, Y.; Suzuki, K.

    2011-04-15

    An analytical method is developed for determining net sputtering rate for an MgO layer under hot ions with low energy (<100 eV) in a neon-xenon discharge gas at near-atmospheric pressure. The primary sputtering rate is analyzed according to spatial and energy distributions of the hot ions with average energy, E{sup h}{sub i}, above a threshold energy of sputtering, E{sub th,i}, multiplied by a yield coefficient. The threshold energy of sputtering is determined from dissociation energy required to remove an atom from MgO surface multiplied by an energy-transfer coefficient. The re-deposition rate of the sputtered atoms is calculated by a diffusion simulation using a hybridized probabilistic and analytical method. These calculation methods are combined to analyze the net sputtering rate. Maximum net sputtering rate due to the hot neon ions increases above the partial pressure of 4% xenon as E{sup h}{sub Ne} becomes higher and decreases near the partial pressure of 20% xenon as ion flux of neon decreases. The dependence due to the hot neon ions on partial pressure and applied voltage agrees well with experimental results, but the dependence due to the hot xenon ions deviates considerably. This result shows that the net sputtering rate is dominated by the hot neon ions. Maximum E{sup h}{sub Ne} (E{sup h}{sub Ne,max} = 5.3 - 10.3 eV) is lower than E{sub th,Ne} (19.5 eV) for the MgO layer; therefore, weak sputtering due to the hot neon ions takes place. One hot neon ion sputters each magnesium and each oxygen atom on the surface and distorts around a vacancy. The ratio of the maximum net sputtering rate is approximately determined by number of the ions at E{sup h}{sub i,max} multiplied by an exponential factor of -E{sub th,i}/E{sup h}{sub i,max}.

  13. A molecular dynamics study of damage accumulation in GaN during ion beam irradiation

    E-print Network

    Nordlund, Kai

    A molecular dynamics study of damage accumulation in GaN during ion beam irradiation J. Nord, K beam irradiation of GaN. First we analyzed individual recoils between 200 eV and 10 keV. We found also observe that nitrogen gas is produced during prolonged irradiation, in agreement with experimental

  14. 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.

  15. In-situ observation of atomic self-organization processes in Xe nanocrystals embedded in Al.

    SciTech Connect

    Mitsuishi, K.; Song, M.; Furuya, K.; Birtcher, R. C.; Allen, C. W.; Donnelly, S. E.

    1998-03-10

    Self-organization processes in Xe nanocrystals embedded in Al are observed with in-situ high-resolution electron microscopy. Under electron irradiation, stacking fault type defects are produced in Xe nanocrystals. The defects recover in a layer by layer manner. Detailed analysis of the video reveals that the displacement of Xe atoms in the stacking fault was rather small for the Xe atoms at boundary between Xe and Al, suggesting the possibility of the stacking fault in Xe precipitate originating inside of precipitate, not at the Al/Xe interface.

  16. Concurrent in situ ion irradiation transmission electron microscope

    SciTech Connect

    Hattar, K.; Bufford, D. C.; Buller, D. L.

    2014-08-29

    An in situ ion irradiation transmission electron microscope has been developed and is operational at Sandia National Laboratories. This facility permits high spatial resolution, real time observation of electron transparent samples under ion irradiation, implantation, mechanical loading, corrosive environments, and combinations thereof. This includes the simultaneous implantation of low-energy gas ions (0.8–30 keV) during high-energy heavy ion irradiation (0.8–48 MeV). In addition, initial results in polycrystalline gold foils are provided to demonstrate the range of capabilities.

  17. Defect studies in ion irradiated AlGaN

    SciTech Connect

    Jagielski, Jacek; Thome, Lionel; Zhang, Yanwen; Wang, Chong M.; Turos, Andrzej; Nowicki, L.; Pagowska, K.; Jozwik, I.

    2010-06-01

    Defects created in Al0.4Ga0.6N crystals by 320 keV Ar ion irradiation were studied by using RBS/C and TEM techniques. One of the main aims of the work was to use a new version of McChasy, a Monte – Carlo simulation code of backscattering spectra, for the analysis of experimental results obtained for a dislocations-containing crystal. Transmission Electron Microscopy technique was used to get a better insight into dislocation and dislocation loop geometries in order to restrict the range of parameters used in simulations. RBS/C analysis was performed in a 1.5 MeV – 3 MeV energy range in order to check if MC simulations correctly reproduce backscattering spectra at different energies.

  18. Sympathetic ophthalmia complicating helium ion irradiation of a choroidal melanoma

    SciTech Connect

    Fries, P.D.; Char, D.H.; Crawford, J.B.; Waterhouse, W.

    1987-11-01

    Sympathetic ophthalmia was diagnosed 49 months after helium ion irradiation of a left choroidal melanoma. The patient maintained good vision until 18 months after therapy, when she developed neovascular glaucoma. This complication required multiple therapeutic procedures, including topical anti-inflammatory and antiglaucomatous drops, 360 degrees peripheral panretinal cryoblation, and a single 180 degrees application of inferior cyclocryotherapy over a 2 1/2-year period. Four weeks after the cyclocryotherapy, inflammation was noted in both eyes, and, one month later, enucleation of the left sympathogenic eye was performed. Serial histopathologic sections showed a full-thickness, fibrovascular, scleral scar and tantalum marker ring suture without uveal incarceration. Penetrating surgical trauma, a uveal melanoma, and multiple nonpenetrating treatments resulted in the development of sympathetic ophthalmia.

  19. Response of nanostructured ferritic alloys to high-dose heavy ion irradiation

    SciTech Connect

    Parish, Chad M.; White, Ryan M.; LeBeau, James M.; Miller, Michael K.

    2014-02-01

    A latest-generation aberration-corrected scanning/transmission electron microscope (STEM) is used to study heavy-ion-irradiated nanostructured ferritic alloys (NFAs). Results are presented for STEM X-ray mapping of NFA 14YWT irradiated with 10 MeV Pt to 16 or 160 dpa at -100°C and 750°C, as well as pre-irradiation reference material. Irradiation at -100°C results in ballistic destruction of the beneficial microstructural features present in the pre-irradiated reference material, such as Ti-Y-O nanoclusters (NCs) and grain boundary (GB) segregation. Irradiation at 750°C retains these beneficial features, but indicates some coarsening of the NCs, diffusion of Al to the NCs, and a reduction of the Cr-W GB segregation (or solute excess) content. Ion irradiation combined with the latest-generation STEM hardware allows for rapid screening of fusion candidate materials and improved understanding of irradiation-induced microstructural changes in NFAs.

  20. Formation of TiO{sub 2} nanorods by ion irradiation

    SciTech Connect

    Zheng, X. D.; Ren, F. Cai, G. X.; Hong, M. Q.; Xiao, X. H.; Wu, W.; Liu, Y. C.; Li, W. Q.; Ying, J. J.; Jiang, C. Z.

    2014-05-14

    Ion beam irradiation is a powerful method to fabricate and tailor the nanostructured surface of materials. Nanorods on the surface of single crystal rutile TiO{sub 2} were formed by N{sup +} ion irradiation. The dependence of nanorod morphology on ion fluence and energy was elaborated. With increasing ion fluence, nanopores grow in one direction perpendicular to the surface and burst finally to form nanorods. The length of nanorods increases with increasing ion energy under same fluence. The development of the nanorod structure is originated from the formation of the nanopores while N{sub 2} bubbles and aggregation of vacancies were responsible for the formation of nanopores and nanorods. Combining C{sup +} ion irradiation and post-irradiation annealing experiments, two qualitative models are proposed to explain the formation mechanism of these nanorods.

  1. Structural modifications of low-energy heavy-ion irradiated germanium

    SciTech Connect

    Steinbach, T.; Wernecke, J.; Wesch, W.; Kluth, P.; Ridgway, M. C.

    2011-09-01

    Heavy-ion irradiation of crystalline germanium (c-Ge) results in the formation of a homogeneous amorphous germanium (a-Ge) layer at the surface. This a-Ge layer undergoes structural modification such as a strong volume expansion accompanied by drastic surface blackening with further ion irradiation. In the present paper we investigate the mechanism of this ion-induced structural modification in a-Ge basically for the irradiation with I ions (3 and 9 MeV) at room and low temperature as a function of ion fluence for the ion incidence angles of {Theta}=7 deg. and {Theta}=45 deg. For comparison, Ag- and Au-ion irradiations were performed at room temperature as a function of the ion fluence. At fluences two orders of magnitude above the amorphization threshold, morphological changes were observed for all irradiation conditions used. Over a wide range of ion fluences we demonstrate that the volume expansion is caused by the formation of voids at the surface and in the depth of the projected ion range. At high ion fluences the amorphous layer transforms into a porous structure as established by cross section and plan view electron microscopy investigations. However, the formation depth of the surface and buried voids as well as the shape and the dimension of the final porous structure depend on the ion fluence, ion species, and irradiation temperature and will be discussed in detail. The rate of the volume expansion (i.e., porous layer formation) depends linearly on the value of {epsilon}{sub n}. This clearly demonstrates that the structural changes are determined solely by the nuclear energy deposited within the amorphous phase. In addition, at high ion fluences all perpendicular ion irradiations lead to a formation of a microstructure at the surface, whereas for nonperpendicular ion irradiations a nonsaturating irreversible plastic deformation (ion hammering) without a microstructure formation is observed. For the irradiation with ion energies of several MeV, the effect of plastic deformation shows a linear dependence on the ion fluence. Based on these results, we provide an explanation for the differences in surface morphology observed for different angles of incidence of the ion beam will be discussed in detail.

  2. Superlattice-like stacking fault array in ion-irradiated GaN

    SciTech Connect

    Ishimaru, Dr. Manabu; Usov, Igor Olegovich; Zhang, Yanwen; Weber, William J

    2012-01-01

    Controlling defects in crystalline solids is of technological importance for realizing desirable materials properties. Irradiation with energetic particles is useful for designing the spatial distribution and concentration of defects in materials. Here, we performed ion irradiation into hexagonal GaN with the wurtzite structure and demonstrated the spontaneous formation of superlattice-like stacking fault arrays. It was found that the modulation period can be controlled by irradiation conditions and post-irradiation heat treatments.

  3. Behaviour of P, Si, Ni impurities and Cr in self ion irradiated Fe-Cr alloys - Comparison to neutron irradiation

    NASA Astrophysics Data System (ADS)

    Pareige, C.; Kuksenko, V.; Pareige, P.

    2015-01-01

    This paper presents an atom probe tomography study of phase transformation and solute segregation in Fe-Cr alloys of low purity under self-ion irradiation. Fe-9%Cr and Fe-12%Cr were irradiated at 100 °C, 300 °C and 420 °C at a dose of 0.5 dpa. Homogeneously distributed clusters enriched in Cr, P, Si and Ni are shown to form at 300 °C and 420 °C but not at 100 °C. Study of the evolution of the segregation intensities of Cr, Si and P in the clusters with temperature under ion irradiation indicates that they form by a radiation induced mechanism. No ?? clusters were observed whatever the irradiation temperature whereas they were observed in the same alloys after neutron irradiation at 300 °C at 0.6 dpa. Comparison of the solute cluster composition after ion irradiation and neutron irradiation, suggests that P atoms could play an important role in the appearance of the solute clusters by stabilizing point defect clusters that could later be enriched in Ni, Si and Cr.

  4. Secondary particle tracks generated by ion beam irradiation

    NASA Astrophysics Data System (ADS)

    García, Gustavo

    2015-05-01

    The Low Energy Particle Track Simulation (LEPTS) procedure is a powerful complementary tool to include the effect of low energy electrons and positrons in medical applications of radiation. In particular, for ion-beam cancer treatments provides a detailed description of the role of the secondary electrons abundantly generated around the Bragg peak as well as the possibility of using transmuted positron emitters (C11, O15) as a complement for ion-beam dosimetry. In this study we present interaction probability data derived from IAM-SCAR corrective factors for liquid environments. Using these data, single electron and positron tracks in liquid water and pyrimidine have been simulated providing information about energy deposition as well as the number and type of interactions taking place in any selected ``nanovolume'' of the irradiated area. In collaboration with Francisco Blanco, Universidad Complutense de Madrid; Antonio Mu noz, Centro de Investigaciones Energéticas Medioambientales y Tecnológicas and Diogo Almeida, Filipe Ferreira da Silva, Paulo Lim ao-Vieira, Universidade Nova de Lisboa. Supported by the Spanish and Portuguese governments.

  5. Evaluation of irradiation hardening of ion-irradiated V-4Cr-4Ti and V-4Cr-4Ti-0.15Y alloys by nanoindentation techniques

    NASA Astrophysics Data System (ADS)

    Miyazawa, Takeshi; Nagasaka, Takuya; Kasada, Ryuta; Hishinuma, Yoshimitsu; Muroga, Takeo; Watanabe, Hideo; Yamamoto, Takuya; Nogami, Shuhei; Hatakeyama, Masahiko

    2014-12-01

    Irradiation hardening behavior of V-4Cr-4Ti and V-4Cr-4Ti-0.15Y alloys after Cu-ion beam irradiation were investigated with a combination between nanoindentation techniques and finite element method (FEM) analysis. The ion-irradiation experiments were conducted at 473 K with 2.4 MeV Cu2+ ions up to 7.6 dpa. For the unirradiated materials, the increase in nanoindentation hardness with decreasing indentation depth, so-called indentation size effect (ISE), was clearly observed. After irradiation, irradiation hardening in the measured depth was identified. Hardening behavior of bulk-equivalent hardness for V-4Cr-4Ti-0.15Y alloy was similar to that for V-4Cr-4Ti alloy. Y addition has little effect on irradiation hardening at 473 K. Adding the concept of geometrically necessary dislocations (GNDs) to constitutive equation of V-4Cr-4Ti alloy, the ISE was simulated. A constant value of ? = 0.5 was derived as an optimal value to simulate nanoindentation test for ion-irradiated V-4Cr-4Ti alloy. Adding the term of irradiation hardening ??irrad. to constitutive equation with ? = 0.5, FEM analyses for irradiated surface of V-4Cr-4Ti alloy were carried out. The analytic data of FEM analyses based on neutron-irradiation hardening equivalent to 3.0 dpa agreed with the experimental data to 0.76 dpa. The comparison indicates that irradiation hardening by heavy ion-irradiation is larger than that by neutron-irradiation at the same displacement damage level. Possible mechanisms for extra hardening by heavy ion-irradiation are the processes that the injected Cu ions could effectively produce irradiation defects such as interstitials compared with neutrons, and that higher damage rate of ion-irradiation enhanced nucleation of irradiation defects and hence increased the number density of the defects compared with neutron-irradiation.

  6. Structural damage in InGaN induced by MeV heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, L. M.; Fadanelli, R. C.; Hu, P.; Zhao, J. T.; Wang, T. S.; Zhang, C. H.

    2015-08-01

    In0.18Ga0.82N films were irradiated with 4 MeV 84Kr and 8.9 MeV 209Bi ions to various fluences at room temperature. The irradiated films were analyzed by means of Rutherford backscattering/channeling (RBS/C) and high resolution X-ray diffraction (HRXRD). The RBS/C measurements show that under the irradiation conditions, the relative lattice disorder in the films, obtained from the normalized backscattering yield, exhibits a rapid increase in the range from ?2% to 68%. There is also an increasing lattice expansion of the films with increasing ion fluence, as determined by the HRXRD measurements. At a comparable level of lattice disorder, the Kr irradiation leads to a more pronounced lattice expansion than the Bi irradiation. This may be attributed to a larger portion of the single interstitials in the films produced by the lighter Kr ion irradiation.

  7. Area-selective formation of Si nanocrystals by assisted ion-beam irradiation during dual-ion-beam deposition

    SciTech Connect

    Kim, Jae Kwon; Cha, Kyu Man; Kang, Jung Hyun; Kim, Yong; Yi, Jae-Yel; Chung, Tae Hun; Bark, Hong Jun

    2004-08-30

    We investigate the effect of Ar-ion-beam irradiation during the deposition of SiO{sub x} films by dual-ion-beam deposition system. Ion-beam irradiation effectively increases the oxygen content, x, in SiO{sub x} films indicative of the preferential sputtering of Si phase as compared to SiO{sub 2} phase in SiO{sub x} films. We observe the intense photoluminescence from nonirradiated sample after postdeposition annealing at 1100 deg. C indicating the formation of Si nanocrystals as shown by a cross-sectional transmission electron microscope. However, the increased oxygen content in ion-beam-irradiated sample results in small optical volume of small Si nanocrystals not sufficient for yielding appreciable photoluminescence intensity after postdeposition annealing. The property is utilized for achieving the area-selective formation of Si nanocrytals by inserting a shadow mask in assist ion beam during deposition.

  8. Nanohole pattern formation on germanium induced by focused ion beam and broad beam Ga{sup +} irradiation

    SciTech Connect

    Fritzsche, Monika; Muecklich, Arndt; Facsko, Stefan

    2012-05-28

    Hexagonally ordered nanohole patterns were produced on Ge(100) surfaces by focused Ga{sup +} ion beam and broad Ga{sup +} ion beam irradiations with 5 keV energy under normal incidence. Identical patterns were obtained by irradiations with a scanning focused ion beam under different irradiation conditions and with a broad Ga{sup +} beam without scanning and five orders of magnitude smaller ion flux. Thus, we could demonstrate that nanohole pattern formation is independent of ion flux over several orders of magnitude and scanning of a focused ion beam under appropriate conditions is identical to broad ion beam irradiation.

  9. Difference of Irradiation Effects between Ar Cluster Ion and Ar+ for DLC film formation

    SciTech Connect

    Kitagawa, T.; Miyauchi, K.; Kanda, K.; Matsui, S.; Toyoda, N.; Tsubakino, H.; Matsuo, J.; Yamada, I.

    2003-08-26

    In order to study the influences of Ar monomer ion (Ar+) on carbon film properties induced by ion beams assisted deposition, Ar cluster ion, Ar+, and their mixed ions (Ar cluster ion and Ar+) irradiated surface during evaporation and deposition of C60. From Near Edge X-ray Absorption Fine Structure (NEXAFS) and Raman spectroscopy measurements, lower sp2 content in carbon films was obtained via Ar cluster ion beam bombardment in comparison with bombardment by Ar+ and mixed ion beams. Furthermore higher hardness and smoothness of surface were demonstrated via Ar cluster ion bombardments. Thus, it was important to irradiate using higher fraction Ar cluster ions in the beam, in order to obtain hard DLC films with flat surface.

  10. Microstructural stability of a self-ion irradiated lanthana-bearing nanostructured ferritic steel

    NASA Astrophysics Data System (ADS)

    Pasebani, Somayeh; Charit, Indrajit; Burns, Jatuporn; Alsagabi, Sultan; Butt, Darryl P.; Cole, James I.; Price, Lloyd M.; Shao, Lin

    2015-07-01

    Thermally stable nanofeatures with high number density are expected to impart excellent high temperature strength and irradiation stability in nanostructured ferritic steels (NFSs) which have potential applications in advanced nuclear reactors. A lanthana-bearing NFS (14LMT) developed via mechanical alloying and spark plasma sintering was used in this study. The sintered samples were irradiated by Fe2+ ions to 10, 50 and 100 dpa at 30 °C and 500 °C. Microstructural and mechanical characteristics of the irradiated samples were studied using different microscopy techniques and nanoindentation, respectively. Overall morphology and number density of the nanofeatures remained unchanged after irradiation. Average radius of nanofeatures in the irradiated sample (100 dpa at 500 °C) was slightly reduced. A notable level of irradiation hardening and enhanced dislocation activity occurred after ion irradiation except at 30 °C and ?50 dpa. Other microstructural features like grain boundaries and high density of dislocations also provided defect sinks to assist in defect removal.

  11. Effect of ion irradiation on the surface, structural and mechanical properties of brass

    NASA Astrophysics Data System (ADS)

    Ahmad, Shahbaz; Bashir, Shazia; Ali, Nisar; Umm-i-Kalsoom; Yousaf, Daniel; Faizan-ul-Haq; Naeem, Athar; Ahmad, Riaz; Khlaeeq-ur-Rahman, M.

    2014-04-01

    Modifications to the surface, structural and mechanical properties of brass after ion irradiation have been investigated. Brass targets were bombarded by carbon ions of 2 MeV energy from a Pelletron linear accelerator for various fluences ranging from 56 × 1012 to 26 × 1013 ions/cm2. A scanning electron microscope and X-ray diffractometer were utilized to analyze the surface morphology and crystallographic structure respectively. To explore the mechanical properties e.g., yield stress, ultimate tensile strength and microhardness of irradiated brass, an universal tensile testing machine and Vickers microhardness tester were used. Scanning electron microscopy results revealed an irregular and randomly distributed sputter morphology for a lower ion fluence. With increasing ion fluence, the incoherently shaped structures were transformed into dendritic structures. Nano/micro sized craters and voids, along with the appearance of pits, were observed at the maximum ion fluence. From X-ray diffraction results, no new phases were observed to be formed in the brass upon irradiation. However, a change in the peak intensity and higher and lower angle shifting were observed, which represents the generation of ion-induced defects and stresses. Analyses confirmed modifications in the mechanical properties of irradiated brass. The yield stress, ultimate tensile strength and hardness initially decreased and then increased with increasing ion fluence. The changes in the mechanical properties of irradiated brass are well correlated with surface and crystallographic modifications and are attributed to the generation, augmentation, recombination and annihilation of the ion-induced defects.

  12. Microstructural evolution in nickel alloy C-276 after Ar-ion irradiation at elevated temperature

    SciTech Connect

    Jin, Shuoxue; He, Xinfu; Li, Tiecheng; Ma, Shuli; Tang, Rui; Guo, Liping

    2012-10-15

    In present work, the irradiation damage in nickel-base alloy C-276 irradiated with Ar-ions was studied. Specimens of C-276 alloy were subjected to an irradiation of Ar-ions (with 120 keV) to dose levels of 6 and 10 dpa at 300 and 550 Degree-Sign C, respectively. The size distributions and densities of dislocation loops caused by irradiation were investigated with transmission electron microscopy. Irradiation hardening due to the formation of the loops was calculated using the dispersed barrier-hardening model, showing that irradiation hardening was greatest at 300 Degree-Sign C/6 dpa. The microstructure evolution induced by Ar-ion irradiation (0-10 dpa) in nickel-base alloy C-276 has been studied using a multi-scale modeling code Radieff constructed based on rate theory, and the size of dislocation loops simulated by Radieff was in good agreement with the experiment. - Highlights: Black-Right-Pointing-Pointer High density of dislocation loops appeared after Ar ions irradiation. Black-Right-Pointing-Pointer Irradiation hardening due to the formation of loops was calculated by the DBH model. Black-Right-Pointing-Pointer Size of loops simulated by Radieff was in good agreement with the experiment.

  13. Comparison of UV and high-energy ion irradiation of methanol:ammonia ice

    E-print Network

    Caro, G M Munoz; Boduch, P; Rothard, H; Domaracka, A; Jimenez-Escobar, A

    2014-01-01

    The main goal of this work is to compare the effects induced in ices of astrophysical relevance by high-energy ions, simulating cosmic rays, and by vacuum ultraviolet (UV) photons. This comparison relies on in situ infrared spectroscopy of irradiated CH3OH:NH3 ice. Swift heavy ions were provided by the GANIL accelerator. The source of UV was a microwave-stimulated hydrogen flow discharge lamp. The deposited energy doses were similar for ion beams and UV photons to allow a direct comparison. A variety of organic species was detected during irradiation and later during ice warm-up. These products are common to ion and UV irradiation for doses up to a few tens of eV per molecule. Only the relative abundance of the CO product, after ice irradiation, was clearly higher in the ion irradiation experiments. For some ice mixture compositions, the irradiation products formed depend only weakly on the type of irradiation, swift heavy ions, or UV photons. This simplifies the chemical modeling of energetic ice processing ...

  14. Effect of gigaelectron volt Au-ion irradiation on the characteristics of ultrananocrystalline diamond films

    SciTech Connect

    Chen, Huang-Chin; Teng, Kuang-Yau; Tang, Chen-Yau; Lin, I-Nan; Sundaravel, Balakrishnan; Amirthapandian, Sankarakumar

    2010-12-15

    The effect of 2.245 GeV Au-ion irradiation/postannealing processes on the electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films was investigated. Au-ion irradiation with a fluence of around 8.4x10{sup 13} ions/cm{sup 2} is required to induce a large improvement in the EFE properties of the UNCD films. Postannealing the Au-ion irradiated films at 1000 deg. C for 1 h slightly degraded the EFE properties of the films but the resulting EFE behavior was still markedly superior to that of pristine UNCD films. Transmission electron microscopy examinations revealed that the EFE properties of the UNCD films are primarily improved by Au-ion irradiation/postannealing processes because of the formation of nanographites along the trajectory of the irradiating ions, which results in an interconnected path for electron transport. In contrast, the induction of grain growth process due to Au-ion irradiation in UNCD films is presumed to insignificantly degrade the EFE properties for the films as the aggregates are scarcely distributed and do not block the electron conducting path.

  15. Nano-porosity in GaSb induced by swift heavy ion irradiation

    SciTech Connect

    Kluth, P. Schnohr, C. S.; Giulian, R.; Araujo, L. L.; Lei, W.; Rodriguez, M. D.; Afra, B.; Bierschenk, T.; Ridgway, M. C.; Sullivan, J.; Weed, R.; Li, W.; Ewing, R. C.

    2014-01-13

    Nano-porous structures form in GaSb after ion irradiation with 185 MeV Au ions. The porous layer formation is governed by the dominant electronic energy loss at this energy regime. The porous layer morphology differs significantly from that previously reported for low-energy, ion-irradiated GaSb. Prior to the onset of porosity, positron annihilation lifetime spectroscopy indicates the formation of small vacancy clusters in single ion impacts, while transmission electron microscopy reveals fragmentation of the GaSb into nanocrystallites embedded in an amorphous matrix. Following this fragmentation process, macroscopic porosity forms, presumably within the amorphous phase.

  16. Effect of 100MeV oxygen ion irradiation on silicon NPN power transistor

    SciTech Connect

    Kumar, M. Vinay; Krishnakumar, K. S.; Dinesh, C. M.; Krishnaveni, S.; Ramani

    2012-06-05

    The radiation response of npn Bipolar junction transistor (BJT) has been examined for 100 MeV O{sup 7+} ion. Key electrical properties like Gummel characteristics, dc current gain and capacitance-voltage of 100MeV O{sup 7+} ion irradiated transistor were studied before and after irradiation. The device was decapped and the electrical characterizations were performed at room temperature. Base current is observed to be more sensitive than collector current and gain appears to be degraded with ion fluence, also considerable degradation in C-V characteristics is observed and doping concentration is found to be increased along with the increase in ion fluence.

  17. Investigation of Current Spike Phenomena During Heavy Ion Irradiation of NAND Flash Memories

    NASA Technical Reports Server (NTRS)

    Oldham, Timothy R.; Berg, Melanie; Friendlich, Mark; Wilcox, Ted; Seidleck, Christina; LaBel, Kenneth A.; Irom, Farokh; Buchner, Steven P.; McMorrow, Dale; Mavis, David G.; Eaton, Paul H.; Castillo, James

    2011-01-01

    A series of heavy ion and laser irradiations were performed to investigate previously reported current spikes in flash memories. High current events were observed, however, none matches the previously reported spikes. Plausible mechanisms are discussed.

  18. Ion Irradiation-induced nano-crystallization metallic glasses (amorphous metal) 

    E-print Network

    Tran, Minh Hong

    2013-02-28

    This project idea is proposed in order to develop the understanding of the mechanisms responsible for Nano-crystal phase formation when metallic glasses (amorphous) is exposed under the high energy ion irradiation and is quantified the resulting...

  19. Investigation of heat release in the targets during irradiation by ion beams

    E-print Network

    O. D. Dalkarov; M. A. Negodaev; A. S. Rusetskii

    2015-07-31

    The DD-reaction is investigated and the heat emission off the targets during their irradiation with ion beams is studied at the HELIS ion accelerator at LPI. The heat emission is observed to be significantly higher in the case of irradiation of the Ti/TiO2:Dx-targets by a D+ beam, as compared to the H+ and Ne+ beams. Furthermore, it depends on the concentration of deuterium in the target and current density of the deuteron beam.

  20. n-Selective Single Capture Following Xe18+ And Xe54+ Impact On Na(3s) And Na*(3p)

    NASA Astrophysics Data System (ADS)

    Otranto, S.; Olson, R. E.; Hasan, V. G.; Hoekstra, R.

    2011-06-01

    State selective single charge exchange n-level cross sections are calculated for collisions of Xe18+ and Xe54+ ions with Na(3s) and Na*(3p) over the energy range of 0.1 to 10.0 keV/amu. The CTMC method is used which includes all two-body interactions. Experimental state-selective cross sections and their corresponding transverse momentum spectra for Xe18+ are found to be in reasonable accord with the calculations.

  1. Oxide shell reduction and magnetic property changes in core-shell Fe nanoclusters under ion irradiation

    SciTech Connect

    Sundararajan, Jennifer A.; Kaur, Maninder; Qiang, You; Jiang, Weilin; McCloy, John S.

    2014-05-07

    Ion irradiation effects are studied on the Fe-based core-shell nanocluster (NC) films with core as Fe and shell as Fe{sub 3}O{sub 4}/Fe{sub 3}N. These NC films were deposited on Si substrates to thickness of ?0.5 ?m using a NC deposition system. The films were irradiated at room temperature with 5.5?MeV Si{sup 2+} ions to ion fluences of 10{sup 15} and 10{sup 16} ions/cm{sup 2}. It is found that the irradiation induces grain growth, Fe valence reduction in the shell, and crystallization or growth of Fe{sub 3}N. The film retained its Fe-core and its ferromagnetic properties after irradiation. The nature and mechanism of oxide shell reduction and composition dependence after irradiation were studied by synthesizing additional NC films of Fe{sub 3}O{sub 4} and FeO?+?Fe{sub 3}N and irradiating them under the same conditions. The presence of nanocrystalline Fe is found to be a major factor for the oxide shell reduction. The surface morphologies of these films show dramatic changes in the microstructures due to cluster growth and agglomeration as a result of ion irradiation.

  2. Carbon nanotubes as masks against ion irradiation: An insight from atomistic simulations

    E-print Network

    Krasheninnikov, Arkady V.

    material allows one to estimate the theoretical limit on the minimum width of the wire which can be made irradiation-induced carbon nanotube welding,2 and cross linking,3 just to mention a few. Experiments also show multiwalled nanotubes MWNTs as masks.4 By irradiating with 300 eV Ar ions, a Au/Ti wire about 10 nm in width

  3. The change in the surface topography of magnesium under high-flux C ion irradiation

    NASA Astrophysics Data System (ADS)

    Potyomkin, G. V.; Ligachev, A. E.; Zhidkov, M. V.; Kolobov, Y. R.; Remnev, G. E.; Y Gazizova, M.; Bozhko, S. A.; Pavlov, S. K.

    2015-11-01

    The topography of the surface of the magnesium sample after irradiation by the high-intensity pulsed ion beam of a TEMP-4M accelerator was studied. The irradiation causes the formation of a regular comb structure and the creation of craters, their depth reaches 1-1.5 ?m.

  4. Simulations of Xe and U diffusion in UO2

    SciTech Connect

    Andersson, Anders D.; Vyas, Shyam; Tonks, Michael R.; Casillas, Luis; Uberuaga, Blas P.; Millett, Paul

    2012-09-10

    Diffusion of xenon (Xe) and uranium (U) in UO{sub 2} is controlled by vacancy mechanisms and under irradiation the formation of mobile vacancy clusters is important. Based on the vacancy and cluster diffusion mechanisms established from density functional theory (DFT) calculations, we derive continuum thermodynamic and diffusion models for Xe and U in UO{sub 2}. In order to capture the effects of irradiation, vacancies (Va) are explicitly coupled to the Xe and U dynamics. Segregation of defects to grain boundaries in UO{sub 2} is described by combining the bulk diffusion model with models of the interaction between Xe atoms and vacancies with grain boundaries, which were derived from atomistic calculations. The diffusion and segregation models were implemented in the MOOSE-Bison-Marmot (MBM) finite element (FEM) framework and the Xe/U redistribution was simulated for a few simple microstructures.

  5. Ion-irradiation of complex hydrocarbons: implications for small Solar System bodies

    NASA Astrophysics Data System (ADS)

    Moroz, L.; Baratta, G.; Distefano, E.; Strazzulla, G.; Dotto, E.; Barucci, M.; Arnold, G.

    2003-04-01

    Trans-Neptunian Objects (TNOs) and cometary nuclei show remarkable color variations. In the visual and near-infrared spectral regions their colors may range from red to gray or bluish. This probably indicates that surface alteration processes such as space weathering and impact resurfacing plays an essential role in the color diversity of such bodies. In particular, some previous laboratory ion-irradiation experiments demonstrated a transformation of surface colors of ices from gray to red and further to gray. Additional possibility is a transformation of originally red dark refractory organic surface components into a gray carbonized material as a result of ion irradiation. We simulated such an "ageing" effect by an irradiation of a natural dark red organic samples (asphaltite and kerite). The samples were irradiated by 30-60 keV H+, N+ and Ar++ ions and their reflectance spectra were measured before and after irradiation. The results indicate that initially red spectra of organics progressively flatten with increasing ion fluences. The laboratory spectra have been compared with astronomical spectra of TNOs. We demonstrate that an observed variety of TNO’ spectral slopes can be reproduced by our laboratory spectra corresponding to different ion fluences. If we assume that fresh surfaces of some TNOs are red due to their refractory organic components, then their irradiation by ion populations in the Solar System in combination with collisional evolution exposing these fresh surfaces could have produced a variety of colors.

  6. Conduction mechanisms in ion-irradiated InGaAs layers

    SciTech Connect

    Joulaud, L.; Mangeney, J.; Chimot, N.; Crozat, P.; Fishman, G.; Bourgoin, J.C.

    2005-03-15

    The electrical and optical properties of H{sup +}- and Au{sup +}-irradiated InGaAs layers were studied using Hall-effect, van der Pauw, and relaxation-time measurements. Comparing the different results allows us to obtain information on the nature of the defects created by these two irradiations. Proton irradiation introduces donor-acceptor paired defects. Gold-ion irradiation creates neutral defect clusters and ionized point defects. The carrier mobilities in all of the irradiated materials are degraded, decreasing with increasing irradiation dose. A scattering model taking into account the paired defects is developed and the mobility evolution calculated from this model agrees with the experimental data of both annealed and unannealed samples. The photocurrent spectra reveal a metallic conduction in the band gap in the case of light-ion irradiation, while such type of conduction does not appear for heavy-ion irradiation. This metallic conduction is a consequence of band tailing induced by shallow defects and vanishes when the material is annealed at 400 deg. C. The proton irradiation-induced defects appear to be related to the EL-2-like defects.

  7. Characterization of selective etching and patterning by sequential light- and heavy-ion irradiation of LiNbO3

    NASA Astrophysics Data System (ADS)

    Huang, Hsu-Cheng; Malladi, Girish; Zhang, Lihua; Dadap, Jerry I.; Kisslinger, Kim; Bakhru, Hassaram; Osgood, Richard M.

    2015-08-01

    The induced selective etching properties of LiNbO3 in a sample subjected to ion processing using sequential light- and heavy-ion irradiation are investigated and discussed. Through the use of TEM and SEM, the lattice structure at the amorphous-crystalline interface is examined after heavy ion exposure and it is found that single-energy amorphizing irradiation results in undercut etching at the interface, while multiple-energy irradiation yields sharper features. Such sequential-irradiation process based on both light- and heavy-ion irradiation enables ready fabrication of concomitant high-resolution patterning and exfoliation of structured freestanding thin films.

  8. Production of defects in supported carbon nanotubes under ion irradiation A. V. Krasheninnikov, K. Nordlund, and J. Keinonen

    E-print Network

    Nordlund, Kai

    .g., the coalescence2 and welding3 of nanotubes under electron irradiation, ion irradiation-induced changes as masks.10 By irradiating with 300-eV Ar ions, a Au/Ti wire a few nanometers in width has been formed just

  9. Anisotropic dislocation loop nucleation in ion-irradiated MgAl sub 2 O sub 4

    SciTech Connect

    Zinkle, S.J.

    1991-01-01

    Polycrystalline disks of stoichiometric magnesium aluminate spinel (MgAl{sub 2}O{sub 4}) were irradiated with 2 MeV Al{sup +} ions at 650{degrees}C and subsequently analyzed in cross-section using transmission electron microscopy (TEM). Interstitial dislocation loops were observed on 110 and 11 habit planes. The population of loops on both sets of habit planes was strongly dependent on their orientation with respect to the ion beam direction. The density of loops with habit plane normals nearly perpendicular to the ion beam direction much higher than loops with habit plane normals nearly parallel to the ion beam direction. On the other hand, the loop size was nearly independent of habit plane orientation. This anisotropic loop nucleation does not occur in ion-irradiated metals such as copper. An additional anomaly associated with ion-irradiated spinel is that the loops on 111 planes were partially unfaulted with a Burgers vector of b = a/4<110>. Previous neutron irradiation studies have never reported unfaulted loops in stoichiometric spinel. Possible cause of the unusual response of spinel to ion irradiation are discussed. 12 refs., 14 figs.

  10. Ordered arrangement of irradiation-induced defects of polycrystalline tungsten irradiated with low-energy hydrogen ions

    NASA Astrophysics Data System (ADS)

    Ni, Weiyuan; Yang, Qi; Fan, Hongyu; Liu, Lu; Berthold, Tobias; Benstetter, Günther; Liu, Dongping

    2015-09-01

    Low-energy (20-520 eV) hydrogen ion irradiations were performed at W surface temperature of 373-1073 K and a fluence ranging from 5.0 × 1023 to 1.0 × 1025/m2. Conductive atomic force microscopy (CAFM) as a nondestructive analytical technique was successfully used to detect irradiation-induced defects in polycrystalline W. The size and density of these nanometer-sized defects were strongly dependent on the fluence of hydrogen ions. Both ion energy (E) and temperature (T) play a crucial role in determining the ordering of nanometer-sized defects. Ordered arrangements were formed at relatively high E and T. This can be attributed to the stress-driven ripple effect of defect growth at crystal grains, resulting in the movement of W lattice along one certain crystal planes.

  11. Magnetic patterning using ion irradiation for highly ordered CoPt alloys with perpendicular anisotropy

    SciTech Connect

    Abes, M.; Venuat, J.; Muller, D.; Carvalho, A.; Schmerber, G.; Beaurepaire, E.; Dinia, A.; Pierron-Bohnes, V.

    2004-12-15

    We used a combination of ion irradiation and e-beam lithography to magnetically pattern an ordered CoPt alloy with strong perpendicular magnetic anisotropy. Ion irradiation disorders the alloy and strongly reduces the magnetic anisotropy. Magnetic force microscopy showed a regular array of 1 {mu}m{sup 2} square dots with perpendicular anisotropy separated by 1 {mu}m large ranges with in-plane anisotropy. This is further confirmed by magnetic measurements, which showed that arrays protected by a 200 nm Pt layer present the same coercive field and the same perpendicular anisotropy as before irradiation. This is promising for applications in magnetic recording technologies.

  12. Modifying the morphology and magnetic properties of magnetite nanoparticles using swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Gokhale, Shubha; Lamba, Subhalakshmi; Kumari, Neha; Singh, Bhupendra; Avasthi, D. K.; Kulkarni, S. K.

    2014-08-01

    Magnetite (Fe3O4) nanospheres of ˜8-11 nm diameter synthesized using a chemical co-precipitation method were deposited as thin films on different substrates using spin coating. The thin films were irradiated with Ag ions at 100 MeV energy. Comparison of unirradiated, as synthesized Fe3O4 nanoparticulate thin film and ion irradiated film shows that irradiation causes dramatic changes in the morphology, structure and magnetic properties. Monte Carlo simulations carried out on this system indicate that the origin of the changes in the magnetic properties lies in the enhanced magnetic anisotropy energy density and reorientation of magnetic easy axis.

  13. Silver ion beam irradiation effects on poly(lactide-co-glycolide) (PLGA)/clay nanocomposites

    NASA Astrophysics Data System (ADS)

    Kaur, Manpreet; Singh, Surinder; Mehta, Rajeev

    2014-12-01

    Swift heavy ions induced modification of thin films of blends of poly(lactide-co-glycolide) (PLGA) (50:50) with organically modified nanoclay (Cloisite® 30B) has been studied, using optical, structural and surface morphological analysis. Presence of nanoclay is found to enhance the properties of this degradable copolymer by reducing the rate of degradation even at high irradiation fluence. Optical and structural analysis of the polymer nanocomposites suggests that both the cross-linking and chain scission phenomenon are caused by swift heavy ion irradiation. XRD measurements show intercalation of PLGA in the clay galleries. Surface morphology of a nanocomposite indicates significant changes after irradiation at various fluences.

  14. Electronic spectroscopy of I2-Xe complexes in solid Krypton

    NASA Astrophysics Data System (ADS)

    Hulkko, Eero; Ahokas, Jussi; Lindgren, Johan; Myllyperkiö, Pasi; Pettersson, Mika

    2012-05-01

    In the present work, we have studied ion-pair states of matrix-isolated I2 with vacuum-UV absorption and UV-vis-NIR emission, where the matrix environment is systematically changed by mixing Kr with Xe, from pure Kr to a more polarizable Xe host. Particular emphasis is put on low doping levels of Xe that yield a binary complex I2-Xe, as verified by coherent anti-Stokes Raman scattering (CARS) measurements. Associated with interaction of I2 with Xe we can observe strong new absorption in vacuum-UV, redshifted 2400 cm-1 from the X ? D transition of I2. Observed redshift can be explained by symmetry breaking of ion-pair states within the I2-Xe complex. Systematic Xe doping of Kr matrices shows that at low doping levels, positions of I2 ion-pair emissions are not significantly affected by complexation with Xe, but simultaneous increase of emissions from doubly spin-excited states indicates non-radiative relaxation to valence states. At intermediate doping levels ion-pair emissions shift systematically to red due to change in the average polarizability of the environment. We have conducted spectrally resolved ultrafast pump-probe ion-pair emission studies with pure and Xe doped Kr matrices, in order to reveal the influence of Xe to I2 dynamics in solid Kr. Strikingly, relaxed emission from the ion-pair states shows no indication of complex presence. It further indicates that the complex escapes detection due to a non-radiative relaxation.

  15. Tuning the conductivity of vanadium dioxide films on silicon by swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Hofsäss, H.; Ehrhardt, P.; Gehrke, H.-G.; Brötzmann, M.; Vetter, U.; Zhang, K.; Krauser, J.; Trautmann, C.; Ko, C.; Ramanathan, S.

    2011-09-01

    We demonstrate the generation of a persistent conductivity increase in vanadium dioxide thin films grown on single crystal silicon by irradiation with 1 GeV 238U swift heavy ions at room temperature. VO2 undergoes a temperature driven metal-insulator-transition (MIT) at 67 °C. After room temperature ion irradiation with high electronic energy loss of 50 keV/nm the conductivity of the films below the transition temperature is strongly increased proportional to the ion fluence of 5.109 U/cm2 and 1.1010 U/cm2. At high temperatures the conductivity decreases slightly. The ion irradiation slightly reduces the MIT temperature. This observed conductivity change is persistent and remains after heating the samples above the transition temperature and subsequent cooling. Low temperature measurements down to 15 K show no further MIT below room temperature. Although the conductivity increase after irradiation at such low fluences is due to single ion track effects, atomic force microscopy (AFM) measurements do not show surface hillocks, which are characteristic for ion tracks in other materials. Conductive AFM gives no evidence for conducting ion tracks but rather suggests the existence of conducting regions around poorly conducting ion tracks, possible due to stress generation. Another explanation of the persistent conductivity change could be the ion-induced modification of a high resistivity interface layer formed during film growth between the vanadium dioxide film and the n-Silicon substrate. The swift heavy ions may generate conducting filaments through this layer, thus increasing the effective contact area. Swift heavy ion irradiation can thus be used to tune the conductivity of VO2 films on silicon substrates.

  16. Study of thickness dependent sputtering in gold thin films by swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Dash, P.; Sahoo, P. K.; Solanki, V.; Singh, U. B.; Avasthi, D. K.; Mishra, N. C.

    2015-12-01

    Gold thin films of varying thickness (10-100 nm) grown on silica substrates by e-beam evaporation method were irradiated by 120 MeV Au ions at 3 × 1012 and 1 × 1013 ions cm-2 fluences. Irradiation induced modifications of these films were probed by glancing angle X-ray diffraction (GAXRD), atomic force microscopy (AFM), Rutherford backscattering spectrometry (RBS) and surface enhanced Raman scattering (SERS). Irradiation didn't affect the structure, the lattice parameter or the crystallite size, but modified the texturing of grains from [1 1 1] to [2 2 0]. RBS indicated thickness dependent sputtering on irradiation. The sputtering yield was found to decrease with increasing thickness. AFM indicated increase of roughness with increasing irradiation fluence for films of all thickness. In agreement with the AFM observation, the gold nanostructures on the surface of 20 nm thick film were found to increase the SERS signal of acridine orange dye attached to these structures. The SERS peaks were amplified by many fold with increasing ion fluence. The effect of 120 MeV Au ion irradiation on the grain texture, surface morphology and SERS activity in addition to the thickness dependent sputtering in gold thin films are explained by the thermal spike model of ion-matter interaction.

  17. Photo-stimulated luminescence of KCl:Eu under X-ray and ion irradiation

    NASA Astrophysics Data System (ADS)

    Hashima, M.; Koshimizu, M.; Asai, K.

    2009-12-01

    We compared the photo-stimulated luminescence (PSL) process of storage phosphor KCl:Eu under the irradiation of X-ray, 2.0 MeV H + ions and 2.0 MeV He + ions. The purpose of the irradiation of H + and He + ions was to mimic the irradiation effects of neutrons. In each case, it was revealed that F-centers were involved in the PSL process. We observed an entirely different fluence-dependent PSL behavior between the X-ray and the ion irradiation, whereas the behavior of the F-center absorption was quite similar. This difference was due to the different yields of the trapping sites for the electrons liberated from the F-centers, and the difference in the yield was ascribed to the difference in the excitation density. This result clearly indicated a marked difference in the PSL process under X-ray and neutron irradiations and indicated that the analysis of the PSL process under ion irradiation is highly important for the application of PSL phosphors to neutron radiography.

  18. Oxide Shell Reduction and Magnetic Property Changes in Core-Shell Fe Nanoclusters under Ion Irradiation

    SciTech Connect

    Sundararajan, Jennifer A.; Kaur, Maninder; Jiang, Weilin; McCloy, John S.; Qiang, You

    2014-02-12

    Ion irradiation effects are studied on the Fe-based core-shell nanocluster (NC) films with core as Fe and shell as Fe3O4/FeO. These NC films were were deposited on Si substrates to thickness of ~0.5 micrometers using a NC deposition system. The films were irradiated at room temperature with 5.5 MeV Si2+ ions to ion fluences of 1015 and 1016 ions/cm2. It is found that the irradiation induces grain growth, Fe valence reduction in the shell, and crystallization of Fe3N. The nature and mechanism of oxide shell reduction and composition dependence after irradiation were studied by synthesizing additional NC films of Fe3O4 and FeO+Fe3N and irradiating them under the same conditions. The presence of nanocrystalline Fe is found to be a major factor for the oxide shell reduction. The surface morphologies of these films show dramatic changes in the microstructures due to cluster growth and agglomeration as a result of ion irradiation.

  19. Ion microbeam irradiation for radiobiology and radical chemistry: status and prospect

    NASA Astrophysics Data System (ADS)

    Khodja, H.

    2011-01-01

    Ion microbeams are commonly used to study local irradiation effects in living cells, as it has been established that ion beam irradiations can lead to deleterious changes in cells that are not struck directly by the microbeam. Such changes, which take place over distances long compared to the size of the irradiation spot and for times long compared to the time of irradiation, are collectively termed radiation-induced bystander effect or RIBE. Free-radical chemistry is frequently invoked to explain the RIBE but no unified model is available at present. Ion microbeams when coupled with advanced methods for observing free radicals are the tools of choice for investigating the chemistry and biological processes governing RIBE.

  20. Defects in 700 keV oxygen ion irradiated ZnO

    NASA Astrophysics Data System (ADS)

    Pal, S.; Sarkar, A.; Chattopadhyay, S.; Chakrabarti, Mahuya; Sanyal, D.; Kumar, P.; Kanjilal, D.; Rakshit, T.; Ray, S. K.; Jana, D.

    2013-09-01

    It is well known that energetic oxygen ions induce heavy crystalline disorder in ZnO, however, systematic study on this regard is very much limited. Here, we present photoluminescence (PL), optical absorption and sheet resistance measurements on poly and single crystalline ZnO samples irradiated with 700 keV O ions. Results have been compared with the effects of 1.2 MeV Ar irradiation on similar ZnO target. Colour change of the samples with increasing O irradiation fluence has also been noted. Non-monotonic variation of room temperature sheet resistance with the increase of fluence has been observed for polycrystalline ZnO. Such an outcome has been understood as point defects transforming to bigger size clusters. Near band edge (NBE) PL emission is largely reduced due to O ion irradiation. However, at 10 K NBE emission can be observed for irradiated polycrystalline samples. Irradiated ZnO single crystal does not show any band to band transition even at 10 K. It is evident that dynamic recovery of defects is more effective in polycrystalline samples. Ultraviolet-visible absorption spectrum of the irradiated ZnO crystal show pronounced sub-band gap absorption. Oxygen irradiation generated new absorption band in ZnO is at 3.05 eV. In the light of earlier reports, this particular band can be ascribed to absorption by neutral oxygen vacancy defects.

  1. Enhancement of impact-induced mechanoluminescence by swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Zhan, T. Z.; Xu, C. N.; Yamada, H.; Terasawa, Y.; Zhang, L.; Iwase, H.; Kawai, M.

    2012-01-01

    In this Letter, we report a strategy using swift heavy ion (SHI) irradiation to enhance the impact-induced mechanoluminescence (ML) in ML materials. The impact-induced ML intensity of CaSrAl2Si2O8:Eu2+ was enhanced by about one order of magnitude by using SHI irradiation. Furthermore, the enhancement was found to depend on electronic stopping power and irradiation fluence. The density of traps of a type suitable for impact-induced ML is considered to be increased by the SHI irradiation, resulting in the impact-induced ML enhancement.

  2. Irradiation effects of intense pulsed ion beam on the surface of Ni 3Al alloy

    NASA Astrophysics Data System (ADS)

    Liu, Zhi-Jian; Le, Xiao-Yun; Yan, Sha; Zhao, Wei-Jiang; Jiang, Xing-Liu

    2005-06-01

    Ni 3Al base alloy was irradiated by intense pulsed ion beam (IPIB) with 250 kV acceleration voltage, 100-200 A/cm 2 current density and 60 ns pulse duration. The surface morphology and the cross-section microstructures were observed with SEM, and the compositions were characterized by XEDS. The results showed that the appearance of craters induced by irradiation is one of the major factors affecting the irradiated surface roughness; irradiation leads to composition changes on the surface of IC6 alloy and may improve mechanical properties of IC6 alloy.

  3. Fabrication of Pt nanoparticle incorporated polymer nanowires by high energy ion and electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Tsukuda, Satoshi; Takahasi, Ryouta; Seki, Shu; Sugimoto, Masaki; Idesaki, Akira; Yoshikawa, Masahito; Tanaka, Shun-Ichiro

    2016-01-01

    Polyvinylpyrrolidone (PVP)-Pt nanoparticles (NPs) hybrid nanowires were fabricated by high energy ion beam irradiation to PVP thin films including H2PtCl6. Single ion hitting caused crosslinking reactions of PVP and reduction of Pt ions within local cylindrical area along an ion trajectory (ion track); therefore, the PVP nanowires including Pt NPs were formed and isolated on Si substrate after wet-development procedure. The number of Pt NPs was easily controlled by the mixed ratio of PVP and H2PtCl6. However, increasing the amount of H2PtCl6 led to decreasing the radial size and separation of the hybrid nanowires during the wet-development. Additional electron beam irradiation after ion beam improved separation of the nanowires and controlled radial sizes due to an increase in the density of crosslinking points inner the nanowires.

  4. Optimal ion acceleration from ultrathin foils irradiated by a profiled laser pulse of relativistic intensity

    SciTech Connect

    Andreev, A. A.; Steinke, S.; Sokollik, T.; Schnuerer, M.; Nickles, P. V.; Avetsiyan, S. Ter; Platonov, K. Yu.

    2009-01-15

    Recent investigations of relativistic laser plasmas have shown that the energy transfer from the laser field to the kinetic ion energy and therefore the attainable maximum energy of the ions increases when ultrathin targets are irradiated by laser pulse without prepulse. In this paper, the influence of the target thickness and laser pulse contrast on the energy of the accelerated ions has been studied theoretically as well as experimentally. An optimum target was searched if a real laser pulse with a certain prepulse irradiates the target.

  5. Mechanism of the Defect Formation in Supported Graphene by Energetic Heavy Ion Irradiation: the Substrate Effect

    PubMed Central

    Li, Weisen; Wang, Xinwei; Zhang, Xitong; Zhao, Shijun; Duan, Huiling; Xue, Jianming

    2015-01-01

    Although ion beam technology has frequently been used for introducing defects in graphene, the associated key mechanism of the defect formation under ion irradiation is still largely unclear. We report a systematic study of the ion irradiation experiments on SiO2-supported graphene, and quantitatively compare the experimental results with molecular dynamic simulations. We find that the substrate is, in fact, of great importance in the defect formation process, as the defects in graphene are mostly generated through an indirect process by the sputtered atoms from the substrate. PMID:25927476

  6. Ion-irradiation-induced densification of zirconia sol-gel thin films

    SciTech Connect

    Levine, T.E.; Giannelis, E.P.; Kodali, P.; Tesmer, J.; Nastasi, M.; Mayer, J.W.

    1994-02-01

    We have investigated the densification behavior of sol-gel zirconia films resulting from ion irradiation. Three sets of films were implanted with neon, krypton, or xenon. The ion energies were chosen to yield approximately constant energy loss through the film and the doses were chosen to yield similar nuclear energy deposition. Ion irradiation of the sol-gel films resulted in carbon and hydrogen loss as indicated by Rutherford backscattering spectrometry and forward recoil energy spectroscopy. Although the densification was hypothesized to result from target atom displacement, the observed densification exhibits a stronger dependence on electronic energy deposition.

  7. 84 MeV C-ions irradiation effects on Zr-45Ti-5Al-3V alloy

    NASA Astrophysics Data System (ADS)

    Wang, Weipeng; Li, Zhengcao; Zhang, Zhengjun; Zhang, Chonghong

    2014-09-01

    Newly developed Zr-45Ti-5Al-3V alloy were irradiated by 84 MeV carbon ions with doses of 4 * 1015 ions/cm2 and 12 * 1015 ions/cm2, respectively. XRD, SEM, TEM, SAD and tensile tests were performed to study the microstructural evolution and mechanical properties modification upon high energy carbon ion irradiation. XRD patterns show no phase change while the diffraction peak position and intensity vary with irradiation doses. Tensile tests verify monotonic change of alloy strengths and elongations upon irradiation. Microstructure observations of the irradiated samples reveal the irradiation-induced precipitation of (Zr,Ti)3C2, which was believed contributing to the alloy hardening. Superlattice was discovered by the SAD patterns of original and irradiated samples and the high energy C-ions implantation was demonstrated to promote the disorder-order transition by introducing lattice defects.

  8. Evidence for interatomic Coulombic decay in Xe K-shell-vacancy decay of XeF2

    NASA Astrophysics Data System (ADS)

    Dunford, R. W.; Southworth, S. H.; Ray, D.; Kanter, E. P.; Krässig, B.; Young, L.; Arms, D. A.; Dufresne, E. M.; Walko, D. A.; Vendrell, O.; Son, S.-K.; Santra, R.

    2012-09-01

    Charge production, charge redistribution, and ion fragmentation are explored in the decay of a Xe K-shell vacancy in XeF2. Coincidence measurements of all ionic fragments in XeF2 provide evidence that an interatomic-Coulombic-decay-like (ICD-like) process plays a role in the cascade decay. The signature of the ICD-like process is an enhancement of the total number of electrons ejected as compared to the case of atomic Xe. The results indicate that the F atoms participate in the decay cascade within the first few femtoseconds after core-hole formation and that fragmentation begins during the decay process.

  9. Strain-dependent Damage in Mouse Lung After Carbon Ion Irradiation

    SciTech Connect

    Moritake, Takashi; Proton Medical Research Center, University of Tsukuba, Tsukuba ; Fujita, Hidetoshi; Yanagisawa, Mitsuru; Nakawatari, Miyako; Imadome, Kaori; Nakamura, Etsuko; Iwakawa, Mayumi; Imai, Takashi

    2012-09-01

    Purpose: To examine whether inherent factors produce differences in lung morbidity in response to carbon ion (C-ion) irradiation, and to identify the molecules that have a key role in strain-dependent adverse effects in the lung. Methods and Materials: Three strains of female mice (C3H/He Slc, C57BL/6J Jms Slc, and A/J Jms Slc) were locally irradiated in the thorax with either C-ion beams (290 MeV/n, in 6 cm spread-out Bragg peak) or with {sup 137}Cs {gamma}-rays as a reference beam. We performed survival assays and histologic examination of the lung with hematoxylin-eosin and Masson's trichrome staining. In addition, we performed immunohistochemical staining for hyaluronic acid (HA), CD44, and Mac3 and assayed for gene expression. Results: The survival data in mice showed a between-strain variance after C-ion irradiation with 10 Gy. The median survival time of C3H/He was significantly shortened after C-ion irradiation at the higher dose of 12.5 Gy. Histologic examination revealed early-phase hemorrhagic pneumonitis in C3H/He and late-phase focal fibrotic lesions in C57BL/6J after C-ion irradiation with 10 Gy. Pleural effusion was apparent in C57BL/6J and A/J mice, 168 days after C-ion irradiation with 10 Gy. Microarray analysis of irradiated lung tissue in the three mouse strains identified differential expression changes in growth differentiation factor 15 (Gdf15), which regulates macrophage function, and hyaluronan synthase 1 (Has1), which plays a role in HA metabolism. Immunohistochemistry showed that the number of CD44-positive cells, a surrogate marker for HA accumulation, and Mac3-positive cells, a marker for macrophage infiltration in irradiated lung, varied significantly among the three mouse strains during the early phase. Conclusions: This study demonstrated a strain-dependent differential response in mice to C-ion thoracic irradiation. Our findings identified candidate molecules that could be implicated in the between-strain variance to early hemorrhagic pneumonitis after C-ion irradiation.

  10. Enhancement of SPHK1 in vitro by carbon ion irradiation in oral squamous cell carcinoma

    SciTech Connect

    Higo, Morihiro; Uzawa, Katsuhiro . E-mail: uzawak@faculty.chiba-u.jp; Kawata, Tetsuya; Kato, Yoshikuni; Kouzu, Yukinao; Yamamoto, Nobuharu; Shibahara, Takahiko; Mizoe, Jun-etsu; Ito, Hisao; Tsujii, Hirohiko; Tanzawa, Hideki

    2006-07-01

    Purpose The purpose of this study was to assess the gene expression changes in oral squamous cell carcinoma (OSCC) cells after carbon ion irradiation. Methods and Materials Three OSCC cell lines (HSC2, Ca9-22, and HSC3) were irradiated with accelerated carbon ion beams or X-rays using three different doses. The cellular sensitivities were determined by clonogenic survival assay. To identify genes the expression of which is influenced by carbon ion irradiation in a dose-dependent manner, we performed Affymetrix GeneChip analysis with HG-U133 plus 2.0 arrays containing 54,675 probe sets. The identified genes were analyzed using the Ingenuity Pathway Analysis Tool to investigate the functional network and gene ontology. Changes in mRNA expression in the genes were assessed by real-time reverse transcriptase-polymerase chain reaction. Results We identified 98 genes with expression levels that were altered significantly at least twofold in each of the three carbon-irradiated OSCC cell lines at all dose points compared with nonirradiated control cells. Among these, SPHK1, the expression of which was significantly upregulated by carbon ion irradiation, was modulated little by X-rays. The function of SPHK1 related to cellular growth and proliferation had the highest p value (p = 9.25e-7 to 2.19e-2). Real-time reverse transcriptase-polymerase chain reaction analysis showed significantly elevated SPHK1 expression levels after carbon ion irradiation (p < 0.05), consistent with microarray data. Clonogenic survival assay indicated that carbon ion irradiation could induce cell death in Ca9-22 cells more effectively than X-rays. Conclusions Our findings suggest that SPHK1 helps to elucidate the molecular mechanisms and processes underlying the biologic response to carbon ion beams in OSCC.

  11. New Ion Beam Materials Laboratory for Materials Modification and Irradiation Effects Research

    SciTech Connect

    Zhang, Yanwen; Crespillo, Miguel L; Xue, Haizhou; Jin, Ke; Chen, Chien-Hung; Fontana, Cristiano L; Graham, Dr. Joseph T.; Weber, William J

    2014-11-01

    A new multifunctional ion beam materials laboratory (IBML) has been established at the University of Tennessee, in partnership with Oak Ridge National Laboratory. The IBML is currently equipped with two ion sources, a 3 MV tandem accelerator, three beamlines and three endstations. The IBML is primarily dedicated to fundamental research on ion-solid interaction, ion beam analysis, ion beam modification, and other basic and applied research on irradiation effects in a wide range of materials. An overview of the IBML facility is provided, and experimental results are reported to demonstrate the specific capabilities.

  12. Depth-dependent phase change in Gd2O3 epitaxial layers under ion irradiation

    NASA Astrophysics Data System (ADS)

    Mejai, N.; Debelle, A.; Thomé, L.; Sattonnay, G.; Gosset, D.; Boulle, A.; Dargis, R.; Clark, A.

    2015-09-01

    Epitaxial Gd2O3 thin layers with the cubic structure were irradiated with 4-MeV Au2+ ions in the 1013-1015 cm-2 fluence range. X-ray diffraction indicates that ion irradiation induces a cubic to monoclinic phase change. Strikingly, although the energy-deposition profile of the Au2+ ions is constant over the layer thickness, this phase transformation is depth-dependent, as revealed by a combined X-ray diffraction and ion channeling analysis. In fact, the transition initiates very close to the surface and propagates inwards, which can be explained by an assisted migration process of irradiation-induced defects. This result is promising for developing a method to control the thickness of the rare-earth oxide crystalline phases.

  13. Pattern-induced magnetic anisotropy in FePt thin films by ion irradiation

    SciTech Connect

    Jaafar, M.; Sanz, R.; McCord, J.; Jensen, J.; Schaefer, R.; Vazquez, M.; Asenjo, A.

    2011-03-01

    The magnetic properties of FePt thin films have been modified by exposing the samples to irradiation of 4 MeV Cl{sup 2+} ions. Patterned magnetic films, without modified topographical profile, were fabricated by irradiating the films through a shadowing micrometric mask. The structural changes, ascribed to the ion-beam-induced amorphization of the thin films, promote the modification of the magnetic anisotropy. In particular, the out-of-plane component of the magnetization decreases simultaneously with an enhancement of in-plane anisotropy by increasing ion fluence. Moreover, the nonirradiated regions present unexpected anisotropic behavior owing to the stray field of the irradiated regions. The control of this effect, which can have unwished consequences for the patterning of magnetic properties by ion bombardment, needs to be suitably addressed.

  14. Ion irradiation of carbonaceous chondrites as a simulation of space weathering on C-complex asteroids

    NASA Astrophysics Data System (ADS)

    Lantz, C.; Brunetto, R.; Barucci, M. A.; Bachelet, C.; Baklouti, D.; Bourçois, J.; Dartois, E.; Duprat, J.; Duret, P.; Engrand, C.; Godard, M.; Ledu, D.; Mivumbi, O.; Fornasier, S.

    2015-10-01

    We are investigating the effects of space weathering on primitive asteroids using ion irradiation on their meteoritic analogs. To do so, we exposed several carbonaceous chondrites (CV Allende, COs Lancé and Frontier Mountain 95002, CM Mighei, CI Alais, and ungrouped Tagish Lake) to 40 keV He+ ions as a simulation of solar wind irradiation using fluences up to 6.1016 ions/cm2 (implantation platform IRMA at CSNSM Orsay). As a test for our new experimental setup, we also studied samples of olivine and diopside. We confirm the reddening and darkening trends on S-type objects, but carbonaceous chondrites present a continuum of behaviors after ion irradiation as a function of the initial albedo and carbon content: from red to blue and from dark to bright.

  15. Three-stage structural modification of carbon nanotubes by swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Jeet, Kiran; Jindal, V. K.; Bharadwaj, L. M.; Bhandari, Rajiv; Dharamvir, Keya

    2012-08-01

    A study on the structural evolution of carbon nanotubes (CNTs) under irradiation by swift heavy ions (SHIs) of widely varying electronic energy loss (Se) values is presented. The control over Se is exercised through the choice of ion species used for irradiation. The ion beams used are those of nickel and gold with energies 60 and 120 MeV, respectively. Structural changes in CNTs were investigated qualitatively using Raman spectroscopy. Results of irradiation indicate that the structural modifications of CNTs can be broadly divided in three stages. At very low fluences the process of healing occurs; at intermediate fluences damage to the surface of CNTs predominates and nano-graphitic formations are seen; at very high fluences, of the order of 1 × 1014 ions/cm2, the system becomes amorphous. The stable nature of single walled carbon nanotubes compared to multiwalled carbon nanotubes, is also established from the Raman spectroscopy results.

  16. Etch-free Formation of Porous Silicon by High-energy Ion Irradiation

    SciTech Connect

    Perez-Bergquist, Alejandro G.; Naab, Fabian U.; Zhang, Yanwen; Wang, Lumin M.

    2011-03-15

    In this study, porous silicon was fabricated without any chemical etching by self-ion implantation of crystalline Si performed at high temperature and at high fluences. The irradiated silicon samples, which remained crystalline under high temperature ion irradiation, exhibited an increased porous fraction with increasing sample temperature at a given fluence, up to the maximum tested temperature of 650º C. Extremely high ion fluences of at least 2 x 10¹? ions/cm² were necessary to produce significant void growth. Comparisons between the porous silicon structures and irradiation-induced porous networks in Ge, GaSb, and InSb are made, and differences in the formation conditions for these porous networks are discussed.

  17. Etch-free formation of porous silicon by high-energy ion irradiation

    SciTech Connect

    Perez-Bergquist, Dr. Alejandro G.; Naab, Fabian U.; Zhang, Yanwen; Wang, Prof. Lumin

    2011-01-01

    In this study, porous silicon was fabricated without any chemical etching by self-ion implantation of crystalline Si performed at high temperature and at high fluences. The irradiated silicon samples, which remained crystalline under high temperature ion irradiation, exhibited an increased porous fraction with increasing sample temperature at a given fluence, up to the maximum tested temperature of 650 C. Extremely high ion fluences of at least 2 1018 ions/cm2 were necessary to produce significant void growth. Comparisons between the porous silicon structures and irradiation-induced porous networks in Ge, GaSb, and InSb are made, and differences in the formation conditions for these porous networks are discussed.

  18. Xe 4d photoionization in Xe@C60, Xe@C240, and Xe@C60@C240

    NASA Astrophysics Data System (ADS)

    Dolmatov, V. K.; Keating, D. A.

    2012-11-01

    Re-evaluated parameters for the square-well potential model for photoionization of endo-fullerenes are proposed and employed to reveal the spectacular modifications in the Xe 4d photoionization giant resonance along the path from Xe@C60 to Xe@C240 to multi-walled Xe@C60@C240.

  19. MeV Au ion irradiation in silicon and nanocrystalline zirconia film deposited on silicon substrate

    NASA Astrophysics Data System (ADS)

    Chang, Yongqin; Zhang, Yanwen; Zhu, Zihua; Edmondson, Philip D.; Weber, William J.

    2012-09-01

    Nanocrystalline zirconia (ZrO2) film with thickness of 305 nm deposited on a silicon substrate was irradiated with 2 MeV Au ions to different fluences at different temperatures. The implanted ion profiles were measured by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and simulated using the stopping and range of ions in matter (SRIM) code, respectively. The experimental results show that a large fraction of the incident Au ions penetrates through the ZrO2 film and are deposited into the Si substrate. At the interface of ZrO2 and Si, a sudden decrease of Au concentration is observed due to the much larger scattering cross section of Au in ZrO2 than in Si. The depth profile of the Au ions is measured in both the ZrO2 films and the Si substrates, and the results show that the Au distribution profiles do not exhibit a dependence on irradiation temperature. The local Au concentration increases proportionally with the irradiation fluence, suggesting that no thermal or irradiation-induced redistribution of the implanted Au ions. However, the Au concentration in the ZrO2 films, as determined by SIMS, is considerably lower than that predicted by the SRIM results, and the penetration depth from the SIMS measurements is much deeper than that from the SRIM predictions. These observations can be explained by an overestimation of the electronic stopping power, used in the SRIM program, for heavy incident ions in light targets. Overestimation of the heavy-ion electronic stopping power may lead to errors in local dose calculation and underestimation of the projected range of slow heavy ions in targets that contain light elements. A quick estimate based on a reduced target density may be used to compensate the overestimation of the electronic stopping power in the SRIM program to provide better ion profile prediction.

  20. Buried amorphous layers by electronic excitation in ion-beam irradiated lithium niobate: Structure and kinetics

    NASA Astrophysics Data System (ADS)

    Olivares, J.; García-Navarro, A.; García, G.; Agulló-López, F.; Agulló-Rueda, F.; García-Cabañes, A.; Carrascosa, M.

    2007-02-01

    The formation of buried heavily damaged and amorphous layers by a variety of swift-ion irradiations (F at 22MeV, O at 20MeV, and Mg at 28MeV) on congruent LiNbO3 has been investigated. These irradiations assure that the electronic stopping power Se(z ) is dominant over the nuclear stopping Sn(z) and reaches a maximum value inside the crystal. The structural profile of the irradiated layers has been characterized in detail by a variety of spectroscopic techniques including dark-mode propagation, micro-Raman scattering, second-harmonic generation, and Rutherford backscattering spectroscopy/channeling. The growth of the damage on increasing irradiation fluence presents two differentiated stages with an abrupt structural transition between them. The heavily damaged layer reached as a final stage is optically isotropic (refractive index n =2.10, independent of bombarding ion) and has an amorphous structure. Moreover, it has sharp profiles and its thickness progressively increases with irradiation fluence. The dynamics under irradiation of the amorphous-crystalline boundaries has been associated with a reduction of the effective amorphization threshold due to the defects created by prior irradiation (cumulative damage). The kinetics of the two boundaries of the buried layer is quite different, suggesting that other mechanisms aside from the electronic stopping power should play a role on ion-beam damage.

  1. Buried amorphous layers by electronic excitation in ion-beam irradiated lithium niobate: Structure and kinetics

    SciTech Connect

    Olivares, J.; Garcia-Navarro, A.; Garcia, G.; Agullo-Lopez, F.; Agullo-Rueda, F.; Garcia-Cabanes, A.; Carrascosa, M.

    2007-02-01

    The formation of buried heavily damaged and amorphous layers by a variety of swift-ion irradiations (F at 22 MeV, O at 20 MeV, and Mg at 28 MeV) on congruent LiNbO{sub 3} has been investigated. These irradiations assure that the electronic stopping power S{sub e}(z) is dominant over the nuclear stopping S{sub n}(z) and reaches a maximum value inside the crystal. The structural profile of the irradiated layers has been characterized in detail by a variety of spectroscopic techniques including dark-mode propagation, micro-Raman scattering, second-harmonic generation, and Rutherford backscattering spectroscopy/channeling. The growth of the damage on increasing irradiation fluence presents two differentiated stages with an abrupt structural transition between them. The heavily damaged layer reached as a final stage is optically isotropic (refractive index n=2.10, independent of bombarding ion) and has an amorphous structure. Moreover, it has sharp profiles and its thickness progressively increases with irradiation fluence. The dynamics under irradiation of the amorphous-crystalline boundaries has been associated with a reduction of the effective amorphization threshold due to the defects created by prior irradiation (cumulative damage). The kinetics of the two boundaries of the buried layer is quite different, suggesting that other mechanisms aside from the electronic stopping power should play a role on ion-beam damage.

  2. Morphological and biochemical responses of Oryza sativa L. (cultivar MR219) to ion beam irradiation*

    PubMed Central

    Ling, Anna Pick Kiong; Ung, Ying Chian; Hussein, Sobri; Harun, Abdul Rahim; Tanaka, Atsushi; Yoshihiro, Hase

    2013-01-01

    Objective: Heavy ion beam, which has emerged as a new mutagen in the mutation breeding of crops and ornamental plants, is expected to result in the induction of novel mutations. This study investigates the morphological and biochemical responses of Oryza sativa toward different doses of carbon ion beam irradiation. Methods: In this study, the dry seeds of O. sativa were irradiated at 0, 20, 40, 60, 80, 100, and 120 Gy, followed by in-vitro germination under controlled conditions. Morphological and biochemical studies were conducted to investigate the morphological and physiological responses of O. sativa towards ion beam irradiation. Results: The study demonstrated that low doses (10 Gy) of ion beam have a stimulating effect on the height, root length, and fresh weight of the plantlets but not on the number of leaves. Meanwhile, doses higher than 10 Gy caused reductions in all the morphological parameters studied as compared to the control samples. The highest total soluble protein content [(2.11±0.47) mg/g FW] was observed in plantlets irradiated at 20 Gy. All irradiated plantlets were found to have 0.85% to 58.32% higher specific activity of peroxidase as compared to the control samples. The present study also revealed that low doses of ion beam (10 and 20 Gy) had negligible effect on the total chlorophyll content of O. sativa plantlets while 40 Gy had a stimulating effect on the chlorophyll content. Plantlets irradiated between 40 to 120 Gy were shown to be 0.38% to 9.98% higher in total soluble nitrogen content which, however, was not significantly different from the control samples. Conclusions: Carbon ion beam irradiation administered at low to moderate doses of 10 to 40 Gy may induce O. sativa mutants with superior characteristics. PMID:24302713

  3. Effect of irradiation parameters on defect aggregation during thermal annealing of LiF irradiated with swift ions and electrons

    SciTech Connect

    Schwartz, K.; Neumann, R.; Trautmann, C.; Volkov, A. E.; Sorokin, M. V.

    2010-10-01

    Absorption spectroscopy were performed to study the effects of thermal annealing on the aggregation of color centers in LiF crystals irradiated with different ions between carbon and uranium of megaelectron volt-gigaelectron volt energy. The beam parameters such as energy, energy loss, and fluence have a pronounced influence on the initial defect composition and concentration as well as their evolution upon thermal annealing. A distinct phenomenon was observed, viz., the enhancement of F{sub n} centers for annealing temperatures between 500 and 700 K, followed by Li colloid formation above 700 K. The phenomenon requires specific irradiation conditions whereas the formation of Mg colloids from Mg impurities occurs in all irradiated crystals. The mechanisms of annealing and colloid formation are discussed.

  4. Fragmentation of biomolecules using slow highly charged ions

    SciTech Connect

    Ruehlicke, C.; Schneider, D.; Balhorn, R.; DuBois, R.

    1996-11-01

    We present first results of biomolecular fragmentation studies with slow highly charged ions (HCI). A layer of the tripeptide RVA was deposited on gold targets and irradiated with slow (few 100 keV) ions, e.g. Xe{sup 50+} and Xe{sup 15+}, extracted from the LLNL EBIT (electron beam ion trap). The secondary ions released upon ion impact were mass analyzed via Time-Of-Flight Secondary-Ion-Mass-Spectrometry (TOF-SIMS). The results show a strong dependence of the positive and negative ion yields on the charge state of the incident ion. We also found that incident ions with high charge states cause the ejection of fragments with a wide mass range as well as the intact molecule (345 amu). The underlying mechanisms are not yet understood but electron depletion of the target due to the high incident charge is likely to cause a variety of fragmentation processes. 6 refs., 2 figs.

  5. Space Plasma Ion Processing of Ilmenite in the Lunar Soil: Insights from In-Situ TEM Ion Irradiation Experiments

    NASA Technical Reports Server (NTRS)

    Christoffersen, R.; Keller, L. P.

    2007-01-01

    Space weathering on the moon and asteroids results largely from the alteration of the outer surfaces of regolith grains by the combined effects of solar ion irradiation and other processes that include deposition of impact or sputter-derived vapors. Although no longer considered the sole driver of space weathering, solar ion irradiation remains a key part of the space weathering puzzle, and quantitative data on its effects on regolith minerals are still in short supply. For the lunar regolith, previous transmission electron microscope (TEM) studies performed by ourselves and others have uncovered altered rims on ilmenite (FeTiO3) grains that point to this phase as a unique "witness plate" for unraveling nanoscale space weathering processes. Most notably, the radiation processed portions of these ilmenite rims consistently have a crystalline structure, in contrast to radiation damaged rims on regolith silicates that are characteristically amorphous. While this has tended to support informal designation of ilmenite as a "radiation resistant" regolith mineral, there are to date no experimental data that directly and quantitatively compare ilmenite s response to ion radiation relative to lunar silicates. Such data are needed because the radiation processed rims on ilmenite grains, although crystalline, are microstructurally and chemically complex, and exhibit changes linked to the formation of nanophase Fe metal, a key space weathering process. We report here the first ion radiation processing study of ilmenite performed by in-situ means using the Intermediate Voltage Electron Microscope- Tandem Irradiation facility (IVEM-Tandem) at Argonne National Laboratory. The capability of this facility for performing real time TEM observations of samples concurrent with ion irradiation makes it uniquely suited for studying the dose-dependence of amorphization and other changes in irradiated samples.

  6. Drastic structure changes in pre-damaged GaAs crystals irradiated with swift heavy ions

    NASA Astrophysics Data System (ADS)

    Komarov, F.; Uglov, V.; Vlasukova, L.; Didyk, A.; Zlotski, S.; Yuvchenko, V.

    2015-10-01

    We have studied structural transformations in pre-damaged GaAs crystals irradiated with high-energy Bi ions (710 MeV, 4.3 × 1012 cm-2). The pre-damage has been created via irradiation with swift electrons (4 MeV, 4 × 1017 cm-2). A structural disorder in irradiated samples has been investigated by means of selective chemical etching (SCE) and X-ray diffraction (XRD) in combination with the material layer-by-layer removal. Character of lattice deformation in the double-irradiated sample gives an evidence of subsurface region's swelling. Strong lattice distortion has been found in the region of Bi ion ranges at the depth of about 30 ?m. The nature of this effect is discussed.

  7. Biodamage via shock waves initiated by irradiation with ions

    PubMed Central

    Surdutovich, Eugene; Yakubovich, Alexander V.; Solov'yov, Andrey V.

    2013-01-01

    Radiation damage following the ionising radiation of tissue has different scenarios and mechanisms depending on the projectiles or radiation modality. We investigate the radiation damage effects due to shock waves produced by ions. We analyse the strength of the shock wave capable of directly producing DNA strand breaks and, depending on the ion's linear energy transfer, estimate the radius from the ion's path, within which DNA damage by the shock wave mechanism is dominant. At much smaller values of linear energy transfer, the shock waves turn out to be instrumental in propagating reactive species formed close to the ion's path to large distances, successfully competing with diffusion. PMID:23411473

  8. Manipulation of transport hysteresis on graphene field effect transistors with Ga ion irradiation

    SciTech Connect

    Wang, Quan; Liu, Shuai; Ren, Naifei

    2014-09-29

    We have studied the effect of Ga ion irradiation on the controllable hysteretic behavior of graphene field effect transistors fabricated on Si/SO{sub 2} substrates. The various densities of defects in graphene were monitored by Raman spectrum. It was found that the Dirac point shifted to the positive gate voltage constantly, while the hysteretic behavior was enhanced first and then weakened, with the dose of ion irradiation increasing. By contrasting the trap charges density induced by dopant and the total density of effective trap charges, it demonstrated that adsorbate doping was not the decisive factor that induced the hysteretic behavior. The tunneling between the defect sites induced by ion irradiation was also an important cause for the hysteresis.

  9. Automatic system for single ion/single cell irradiation based on Cracow microprobe

    NASA Astrophysics Data System (ADS)

    Veselov, O.; Polak, W.; Lekki, J.; Stachura, Z.; Lebed, K.; Stycze?, J.; Ugenskiene, R.

    2006-05-01

    Recently, the Cracow ion microprobe has found its new application as a single ion hit facility (SIHF), allowing precise irradiations of living cells by a controlled number of ions. The instrument enables a broad field of research, such as survival studies, adaptive response investigations, bystander effect, inverse dose-rate effect, low-dose hypersensitivity, etc. This work presents principles of construction and operation of the SIHF based on the Cracow microprobe. We discuss some crucial features of optical, positioning, and blanking systems, including self-developed software responsible for semiautomatic cell recognition, for precise positioning of cells, and for controlling the irradiation process. We also show some tests carried out to determine the efficiency of the whole system and of its segments. In addition, we present results of the first irradiation measurements performed with living cells.

  10. First tests of the ion irradiation and implantation beamline at the CMAM

    NASA Astrophysics Data System (ADS)

    Jiménez-Rey, D.; Benedicto, M.; Muñoz-Martín, A.; Bachiller-Perea, D.; Olivares, J.; Climent-Font, A.; Gómez-Ferrer, B.; Rodríguez, A.; Narros, J.; Maira, A.; Álvarez, J.; Nakbi, A.; Zucchiatti, A.; de Aragón, F.; García, J. M.; Vila, R.

    2014-07-01

    The implantation and irradiation beamline of the Tandem ion accelerator of the Centro de Micro Análisis de Materiales (CMAM), in Madrid, has been recently completed with a beam sweep and monitoring system, and a cryostat/furnace. These new implementations convert the beamline into a versatile tool to implant ions, between H and Au2, in different materials with precise control of the sample temperature, which may be varied between -180 °C and 600 °C. The size of the swept area on target may be as large as 10 × 10 cm2. The implantation chamber also allows carrying out in situ or/and on line analyses during the irradiations by means of advanced optical measurements, as well as ion beam analyses (IBA). These advancements can be employed in novel applications such as the fabrication of optical waveguides and irradiation tests of structural and functional materials for future fusion reactors. The results of beam tests and first experiments are shown.

  11. Localized dose delivering by ion beam irradiation for experimental trial of establishing brain necrosis model.

    PubMed

    Takata, Takushi; Kondo, Natsuko; Sakurai, Yoshinori; Tanaka, Hiroki; Hasegawa, Takashi; Kume, Kyo; Suzuki, Minoru

    2015-11-01

    Localized dose delivery techniques to establish a brain radiation necrosis model are described. An irradiation field was designed by using accelerated protons or helium ions with a spread-out Bragg peak. Measurement of the designed field confirmed that a high dose can be confined to a local volume of an animal brain. The irradiation techniques described here are very useful for establishing a necrosis model without existence of extraneous complications. PMID:26454176

  12. Nitric oxide-mediated bystander signal transduction induced by heavy-ion microbeam irradiation.

    PubMed

    Tomita, Masanori; Matsumoto, Hideki; Funayama, Tomoo; Yokota, Yuichiro; Otsuka, Kensuke; Maeda, Munetoshi; Kobayashi, Yasuhiko

    2015-07-01

    In general, a radiation-induced bystander response is known to be a cellular response induced in non-irradiated cells after receiving bystander signaling factors released from directly irradiated cells within a cell population. Bystander responses induced by high-linear energy transfer (LET) heavy ions at low fluence are an important health problem for astronauts in space. Bystander responses are mediated via physical cell-cell contact, such as gap-junction intercellular communication (GJIC) and/or diffusive factors released into the medium in cell culture conditions. Nitric oxide (NO) is a well-known major initiator/mediator of intercellular signaling within culture medium during bystander responses. In this study, we investigated the NO-mediated bystander signal transduction induced by high-LET argon (Ar)-ion microbeam irradiation of normal human fibroblasts. Foci formation by DNA double-strand break repair proteins was induced in non-irradiated cells, which were co-cultured with those irradiated by high-LET Ar-ion microbeams in the same culture plate. Foci formation was suppressed significantly by pretreatment with an NO scavenger. Furthermore, NO-mediated reproductive cell death was also induced in bystander cells. Phosphorylation of NF-?B and Akt were induced during NO-mediated bystander signaling in the irradiated and bystander cells. However, the activation of these proteins depended on the incubation time after irradiation. The accumulation of cyclooxygenase-2 (COX-2), a downstream target of NO and NF-?B, was observed in the bystander cells 6 h after irradiation but not in the directly irradiated cells. Our findings suggest that Akt- and NF-?B-dependent signaling pathways involving COX-2 play important roles in NO-mediated high-LET heavy-ion-induced bystander responses. In addition, COX-2 may be used as a molecular marker of high-LET heavy-ion-induced bystander cells to distinguish them from directly irradiated cells, although this may depend on the time after irradiation. PMID:26256626

  13. Combined High Pressure and Heavy-Ion Irradiation: a Novel Approach

    SciTech Connect

    Lang, M.; Zhang, F; Lian, J; Trautmann, C; Neumann, R; Ewing, R

    2009-01-01

    Swift heavy-ion irradiations of a wide variety of materials have been used to modify and manipulate the properties of solids at the nanoscale. Recently, these high-energy irradiations have been successfully combined with high-pressure experiments. Based on results obtained for zircon (ZrSiO{sub 4}), this paper introduces this new experimental approach involving diamond anvil cells and large ion-accelerator facilities. This technique provides a wide spectrum of geoscience applications from nanoscale simulations of fission-track formation under crustal conditions to phase transitions of radiation-damaged minerals resulting from meteorite impact.

  14. Depth distribution of displacement damage in. cap alpha. -iron under triple beam ion irradiation

    SciTech Connect

    Horton, L.L.; Bentley, J.; Jesser, W.A.

    1981-01-01

    The depth dependence of the defect structures was determined for iron irradiated at 850/sup 0/K with 4 MeV Fe/sup 2 +/ and energetic helium and deuteron ions to 10 dpa and fusion levels of helium and deuterium. From the damage profiles, a sectioning depth of 0.9 ..mu..m was selected for studies of iron and bcc iron alloys, such as ferritic steels, utilizing similar irradiation parameters. A comparison of the experimental damage profile to the deposited energy and deposited ion profiles calculated by E-DEP-1 indicated a possible overestimate of the LSS stopping power of at least 22%.

  15. Enhancement of ferromagnetism in Pd nanoparticle by swift heavy ion irradiation

    SciTech Connect

    Kulriya, P. K.; Mehta, B. R.; Avasthi, D. K.; Agarwal, D. C.; Thakur, P.; Brookes, N. B.; Chawla, A. K.; Chandra, R.

    2010-02-01

    In this study, the effect of swift heavy ion irradiation on the magnetic properties of the Pd nanoparticles has been investigated. Structural investigations along with superconducting quantum interface device measurements show that ferromagnetic properties of the Pd nanoparticles are due to the deviation of their electronic structure from that of bulk. The electronic structure is further modified due to the creation of defects on ion irradiation, which results in 20 times increase in the saturation magnetization. The present study establishes that the defect induced modification of Pd 4d electronic structure is responsible for the ferromagnetic properties of the Pd nanoparticles.

  16. Optical waveguides in Yb:SBN crystals fabricated by swift C3+ ion irradiation

    NASA Astrophysics Data System (ADS)

    Liu, Guiyuan; Dong, Ningning; Wang, Jun; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng

    2016-01-01

    We report on the fabrication of optical planar waveguides supporting both the TE and TM confinements in Yb:SBN crystal by swift C3+ ions irradiation. A combination of the micro-photoluminescence and micro-Raman investigations have evidenced the presence of lattice distortion, damage and disordering of the SBN network along the ion irradiation path, with these effects being at the basis of the refractive index modification. The enhanced micro-photoluminescence and micro-Raman intensity in the waveguide volumes show the potential application of the obtained waveguides as active laser gain media.

  17. Photoinduced currents in pristine and ion irradiated kapton-H polyimide

    SciTech Connect

    Sharma, Anu Sridharbabu, Y. Quamara, J. K.

    2014-10-15

    The photoinduced currents in pristine and ion irradiated kapton-H polyimide have been investigated for different applied electric fields at 200°C. Particularly the effect of illumination intensity on the maximum current obtained as a result of photoinduced polarization has been studied. Samples were irradiated by using PELLETRON facility, IUAC, New Delhi. The photo-carrier charge generation depends directly on intensity of illumination. The samples irradiated at higher fluence show a decrease in the peak current with intensity of illumination. The secondary radiation induced crystallinity (SRIC) is responsible for the increase in maximum photoinduced currents generated with intensity of illumination.

  18. Ion irradiation induced enhancement of out-of-plane magnetic anisotropy in ultrathin Co films

    SciTech Connect

    Mazalski, P.; Kurant, Z.; Maziewski, A.; Liedke, M. O.; Fassbender, J.; Baczewski, L. T.; Wawro, A.

    2013-05-07

    Ga{sup +} or He{sup +} irradiated MBE grown ultrathin films of sapphire/Pt/Co(d{sub Co})/Pt(d{sub Pt}) were studied using polar Kerr effect in wide ranges of both cobalt d{sub Co} and platinum d{sub Pt} thicknesses as well as ion fluences F. Two branches of increased magnetic anisotropy and enhanced Kerr rotation angle induced by Ga{sup +} or He{sup +} irradiation are clearly visible in two-dimensional (d{sub Co}, LogF) diagrams. Only Ga{sup +} irradiation induces two branches of out-of-plane magnetization state.

  19. Evaluation of surface damage on organic materials irradiated with Ar cluster ion beam

    SciTech Connect

    Yamamoto, Y.; Ichiki, K.; Ninomiya, S.; Matsuo, J.; Seki, T.; Aoki, T.

    2011-01-07

    The sputtering yields of organic materials under large cluster ion bombardment are much higher than those under conventional monomer ion bombardment. The sputtering rate of arginine remains constant with fluence for an Ar cluster ion beam, but decreases with fluence for Ar monomer. Additionally, because Ar cluster etching induces little damage, Ar cluster ion can be used to achieve molecular depth profiling of organic materials. In this study, we evaluated the damage to poly methyl methacrylate (PMMA) and arginine samples irradiated with Ar atomic and Ar cluster ion beams. Arginine samples were analyzed by secondary ion mass spectrometry (SIMS) and PMMA samples were analyzed by X-ray photoelectron spectroscopy (XPS). The chemical structure of organic materials remained unchanged after Ar cluster irradiation, but was seriously damaged. These results indicated that bombardment with Ar cluster ions induced less surface damage than bombardment with Ar atomic ion. The damage layer thickness with 5 keV Ar cluster ion bombardment was less than 1 nm.

  20. Damage Profiles and Ion Distribution in Pt-irradiated SiC

    SciTech Connect

    Xue, Haizhou; Zhang, Yanwen; Zhu, Zihua; Zhang, Weiming; Bae, Dr. In-Tae; Weber, William J

    2012-01-01

    Single crystalline 6H-SiC samples were irradiated at 150 K using 2MeV Pt ions. Local volume swelling is determined by electron energy loss spectroscopy (EELS), a nearly sigmoidal dependence with irradiation dose is observed. The disorder profiles and ion distribution are determined by Rutherford backscattering spectrometry (RBS), transmission electron microscopy and secondary ion mass spectrum. Since the volume swelling reaches 12% over the damage region under high ion fluence, lattice expansion is considered and corrected during the data analysis of RBS spectra to obtain depth profiles. Projectile and damage profiles are estimated by SRIM (Stopping and Range of Ions in Matter). Comparing with the measured profiles, SRIM code significantly overestimates the electronic stopping power for the slow heavy Pt ions, and large derivations are observed in the predicted ion distribution and the damage profiles. Utilizing the reciprocity method that is based on the invariance of the inelastic excitation in ion atom collisions against interchange of projectile and target, much lower electronic stopping is deduced. A simple approach based on reducing the density of SiC target in SRIM simulation is proposed to compensate the overestimated SRIM electronic stopping power values. Better damage profile and ion range are predicted.

  1. Damage Profiles and Ion Distribution in Pt-irradiated SiC

    SciTech Connect

    Xue, Haizhou; Zhang, Yanwen; Zhu, Zihua; Zhang, Weiming; Bae, In-Tae; Weber, William J.

    2012-09-01

    Single crystalline 6H-SiC samples were irradiated at 150 K with 2 MeV Pt ions. The local volume swelling was determined by electron energy loss spectroscopy (EELS), and a nearly sigmoidal dependence on irradiation dose is observed. The disorder profiles and ion distribution were determined by Rutherford backscattering spectrometry (RBS), transmission electron microscopy, and secondary ion mass spectrometry. Since the volume swelling reaches 12% over the damage region at high ion fluence, the effect of lattice expansion is considered and corrected for in the analysis of RBS spectra to obtain depth profiles. Projectile and damage profiles are estimated by SRIM (Stopping and Range of Ions in Matter).When compared with the measured profiles, the SRIM code predictions of ion distribution and the damage profiles are underestimated due to significant overestimation of the electronic stopping power for the slow heavy Pt ions. By utilizing the reciprocity method, which is based on the invariance of the inelastic energy loss in ion-solid collisions against interchange of projectile and target atom, a much lower electronic stopping power is deduced. A simple approach, based on reducing the density of SiC target in SRIM simulation, is proposed to compensate the overestimated SRIM electronic stopping power values, which results in improved agreement between predicted and measured damage profiles and ion ranges.

  2. Mutation induction in bacteria after heavy ion irradiation

    NASA Technical Reports Server (NTRS)

    Horneck, G.; Kozubek, S.

    1994-01-01

    From a compilation of experimental data on the mutagenic effects of heavy ions in bacteria, main conclusions have been drawn as follows: (1) The mutagenic efficacy of heavy ions in bacteria depends on physical and biological variables. Physical variables are the radiation dose, energy and charge of the ion; the biological variables are the bacterial strain, the repair genotype of bacteria, and the endpoint investigated (type of mutation, induction of enzymes related to mutagenesis); (2) The responses on dose or fluence are mainly linear or linear quadratic. The quadratic component, if found for low LET radiation, is gradually reduced with increasing LET; (3) At low values of Z and LET the cross section of mutation induction sigma m (as well as SOS response, sigma sos. and lambda phage induction, sigma lambda versus LET curves can be quite consistently described by a common function which increases up to approximately 100 keV/mu m. For higher LET values, the sigma(m) versus LET curves show the so-called 'hooks' observed also for other endpoints; (4) For light ions (Z is less than or equal to 4), the cross sections mostly decrease with increasing ion energy, which is probably related to the decrease of the specific energy departed by the ion inside the sensitive volume (cell). For ions in the range of Z = 10, sigma(m) is nearly independent on the ion energy. For heavier ions (Z is greater than or equal to 16), sigma(m) increases with the energy up to a maximum or saturation around 10 MeV/u. The increment becomes steeper with increasing atomic number of the ion. It correlates with the increasing track radius of the heavy ion; (5) The mutagenic efficiency per lethal event changes slightly with ion energy, if Z is small indicating a rough correlation between cellular lethality and mutation induction, only. For ions of higher Z this relation increases with energy, indicating a change in the 'mode' of radiation action from 'killing-prone' to 'mutation-prone'; and (6) Repair genotype substantially influences the radiation induced mutagenesis. Different mechanisms of mutation induction and/or different types of biologically significant lesions in wild type cells compared to repair deficient strains are a likely explanation.

  3. Erosion and deuterium retention in ion-irradiated tungsten under plasma exposure

    NASA Astrophysics Data System (ADS)

    Khripunov, B.; Gureev, V.; Koidan, V.; Kornienko, S.; Latushkin, S.; Petrov, V.; Ryazanov, A.; Semenov, E.; Stolyarova, V.; Danelyan, L.; Kulikauskas, V.; Zatekin, V.; Unezhev, V.

    2015-08-01

    Effect of radiation damage on tungsten response to plasma exposure is examined. Samples of tungsten W 99.95 wt% were irradiated with fast 12C3+ ions at 10 MeV to fluence of (1-2) × 1017 ion/cm2 to produce damage in the range 1-40 dpa relevant to the level of interest for fusion research. Exposure of the irradiated tungsten to deuterium plasma on linear simulator in erosion condition provided D-ion total fluence (1-3) × 1021 D+/cm2 at ion energy 250 eV. Swelling effect has been observed, and important changes in the structure of the irradiated material have been found (SEM). Erosion of the damaged layer was evaluated at Yd-w ? (3-5) ? 10-3 at/ion. The retained deuterium profiles have been taken by ERDA, maximal deuterium concentration reached 6-8 at.% in the layer ?30 nm deep corresponding to 2-3 dpa. Comparison of D-retention was made for C- and He-irradiated tungsten for this level of damage.

  4. Amorphization of nanocrystalline monoclinic ZrO2 by swift heavy ion irradiation.

    PubMed

    Lu, Fengyuan; Wang, Jianwei; Lang, Maik; Toulemonde, Marcel; Namavar, Fereydoon; Trautmann, Christina; Zhang, Jiaming; Ewing, Rodney C; Lian, Jie

    2012-09-21

    Bulk ZrO(2) polymorphs generally have an extremely high amorphization tolerance upon low energy ion and swift heavy ion irradiation in which ballistic interaction and ionization radiation dominate the ion-solid interaction, respectively. However, under very high-energy irradiation by 1.33 GeV U-238, nanocrystalline (40-50 nm) monoclinic ZrO(2) can be amorphized. A computational simulation based on a thermal spike model reveals that the strong ionizing radiation from swift heavy ions with a very high electronic energy loss of 52.2 keV nm(-1) can induce transient zones with temperatures well above the ZrO(2) melting point. The extreme electronic energy loss, coupled with the high energy state of the nanostructured materials and a high thermal confinement due to the less effective heat transport within the transient hot zone, may eventually be responsible for the ionizing radiation-induced amorphization without transforming to the tetragonal polymorph. The amorphization of nanocrystalline zirconia was also confirmed by 1.69 GeV Au ion irradiation with the electronic energy loss of 40 keV nm(-1). These results suggest that highly radiation tolerant materials in bulk forms, such as ZrO(2), may be radiation sensitive with the reduced length scale down to the nano-metered regime upon irradiation above a threshold value of electronic energy loss. PMID:22858872

  5. Simulation of neutron-induced damage in tungsten by irradiation with energetic self-ions

    NASA Astrophysics Data System (ADS)

    Ogorodnikova, O. V.; Gann, V.

    2015-05-01

    A direct comparison of the deuterium (D) decoration of radiation-induced damage in polycrystalline tungsten irradiated with self-ions [present work] and neutrons in the high-flux isotope reactor (HFIR) (Hatano et al., 2013) shows a reasonably good agreement at least up to 0.3 displacement per atom indicating that MeV heavy ions can be a good proxy to simulate neutron-produced damage at room temperature and low dpa. The coefficient of similarity between two kinds of irradiation was obtained experimentally to be Kexp ? 0.65 ± 0.1 in the case of the deuterium decoration of both kinds of radiation-induced defects with low and high de-trapping energies for deuterium. We introduced the theoretical estimation for coefficient of similarity between neutron- and self-ion-irradiations, which is a fraction of common area under the curves of two overlapping damage energy spectra of primary knock-on atom (PKA) produced in tungsten by these two types of irradiation. In other words, Ksim is a part of displaced atoms produced in the similar conditions under two different types of irradiation. The theoretical values of Ksim = 0.34 and Ksim = 0.29 were obtained for tungsten target irradiated with 20 MeV self-ions in comparison to irradiation with neutrons in HFIR reactor (>0.1 MeV) and 14 MeV neutrons, respectively. The theoretical value of Ksim = 0.34 is about two times less than the experimental value of Kexp = 0.65. It means that high energy PKAs can play more important role in the production of similar damage structure by irradiation with self-ions and neutrons which is responsible for deuterium retention. The model assuming that all cascades with an energy higher than Tc = 150 keV split into identical sub-cascades gives the value of Ksim = 0.64 ± 0.01 for the coefficient of similarity between HFIR-neutron and 20 MeV self-ion irradiations that is in an agreement with experimental value of Kexp = 0.65 ± 0.1. Consequently, splitting of high-energy part of cascades might take place in W that results in a reduction of the effective PKA spectrum and a change of types and density of post-radiation defects.

  6. Irradiation effects of graphene and thin layer graphite induced by swift heavy ions

    NASA Astrophysics Data System (ADS)

    Zeng, Jian; Liu, Jie; Zhang, Sheng-Xia; Zhai, Peng-Fei; Yao, Hui-Jun; Duan, Jing-Lai; Guo, Hang; Hou, Ming-Dong; Sun, You-Mei

    2015-08-01

    Graphene and thin graphite films deposited on SiO2/Si are irradiated by swift heavy ions (209Bi, 9.5 MeV/u) with the fluences in a range of 1011 ions/cm2-1012 ions/cm2 at room temperature. Both pristine and irradiated samples are investigated by Raman spectroscopy. For pristine graphite films, the “blue shift” of 2D bond and the “red shift” of G bond with the decrease of thickness are found in the Raman spectra. For both irradiated graphene and thin graphite films, the disorder-induced D peak and D? peak are detected at the fluence above a threshold ?th. The thinner the film, the lower the ?th is. In this work, the graphite films thicker than 60 nm reveal defect free via the absence of a D bond signal under the swift heavy ion irradiation till the fluence of 2.6 × 1012 ions/cm2. For graphite films thinner than 6 nm, the area ratios between D peak and G peak increase sharply with reducing film thickness. It concludes that it is much easier to induce defects in thinner films than in thicker ones by swift heavy ions. The intensities of the D peak and D? peak increase with increasing ion fluence, which predicts the continuous impacting of swift heavy ions can lead to the increasing of defects in samples. Different defect types are detected in graphite films of different thickness values. The main defect types are discussed via the various intensity ratios between the D peak and D? peak (HD/HD?). Project supported by the National Natural Science Foundation of China (Grant Nos. 11179003, 10975164, 10805062, 11005134, and 11275237).

  7. The Influence of High-Energy Lithium Ion Irradiation on Electrical Characteristics of Silicon and GaAs Solar Cells

    E-print Network

    B. Jayashree; Ramani; M. C. Radhakrishna; Anil Agrawal; Saif Ahmad Khan; A. Meulenberg

    2006-10-22

    Space-grade Si and GaAs solar cells were irradiated with 15 & 40 MeV Li ions. Illuminated (AM0 condition) and unilluminated I-V curves reveal that the effect of high-energy Li ion irradiation has produced similar effects to that of proton irradiation. However, an additional, and different, defect mechanism is suggested to dominate in the heavier-ion results. Comparison is made with proton-irradiated solar-cell work and with non-ionizing energy-loss (NIEL) radiation-damage models.

  8. Formation of nanoparticles by ion beam irradiation of thin films.

    PubMed

    Baji, Z; Szanyo, A; Molnár, G; Tóth, A L; Peto, G; Frey, K; Kotai, E; Kaptay, G

    2012-06-01

    The possibility of fabricating nanoparticles by ion bombardment was investigated by the ion bombardment of indium films on oxide covered Si and Cr surfaces. The different masses of implanting specimen ensured the different energy transfer while the same Si substrate ensured the same thermal conductivity for the In and Cr layers. Chromium served as a reference for the effect of ion bombardment and as a substrate as well. The SRIM program was used to simulate the ion surface interaction process. The nanoparticles were detected by scanning electron microscopy (SEM). We found that the melting of the In layer results in the formation of nanoparticles of 50-300 nm diameter and 5-10 nm height. This method can be promising for nanoparticle formation of materials with low melting point. PMID:22905568

  9. Multispecies ion acceleration off laser-irradiated water droplets

    SciTech Connect

    Kemp, A.J.; Ruhl, H.

    2005-03-01

    In a recent experiment at Max-Born Institut, Berlin, strong modulations have been observed in energy spectra of MeV ions that were accelerated by ultrashort intense laser pulses, {tau}{sub L}=35 fs, I=10{sup 19} W/cm{sup 2}, off water droplets. This experiment is studied analytically as well as by numerical particle-in-cell simulations in one and two dimensions and it is shown how classical isothermal fluid expansion models fail in the present case. The paper investigates alternative models which claim to describe the ion spectral modulations and a mechanism that generates proton spectra similar to the experimental ones due to a simultaneous acceleration of several ion components. Finally, the issue of directional anisotropy in the spectra of accelerated ions for the case of a spherical target is discussed.

  10. Silicon Carbide Power Device Performance Under Heavy-Ion Irradiation

    NASA Technical Reports Server (NTRS)

    Lauenstein, Jean-Marie; Casey, Megan; Topper, Alyson; Wilcox, Edward; Phan, Anthony; Ikpe, Stanley; LaBel, Ken

    2015-01-01

    Heavy-ion induced degradation and catastrophic failure data for SiC power MOSFETs and Schottky diodes are examined to provide insight into the challenge of single-event effect hardening of SiC power devices.

  11. Ion Irradiation of Asphaltite: Optical Effects and Implications for Trans-Neptunian Objects and Centaurs

    NASA Astrophysics Data System (ADS)

    Moroz, L. V.; Baratta, G.; Distefano, E.; Strazzulla, G.; Starukhina, L. V.; Dotto, E.; Barucci, M. A.

    2003-06-01

    Trans-Neptunian Objects (TNOs) and Centaurs show remarkable colour variations in the visual and near-infrared spectral regions. Surface alteration processes such as space weathering (e.g., bombardment with ions) and impact resurfacing may play an important role in the colour diversity of such bodies. Ion irradiation of hydrocarbon ices and their mixtures with water ice transforms neutral (grey) surface colours of ices to red and further to grey. Along with the ices, TNOs and Centaurs probably contain complex carbonaceous compounds, in particular, complex hydrocarbons. Unlike ices, such refractory organic materials have originally low visual albedos and red colours in the visible and near-infrared ranges. Here we present the first results of ion irradiation experiments on asphaltite. Asphaltite is a natural complex hydrocarbon material. The reflectance spectra of asphaltite in the 0.4-0.8 ?m range have been recorded before irradiation and after each irradiation step. We demonstrate that irradiation of this red dark material with 30 keV H+ and 15 keV N+ ions gradually transforms its colour from red to grey as a result of carbonization. A moderate increase in the visual albedo has been observed. These results may imply that the surfaces of primitive red objects optically dominated by complex refractory organics may show a similar space weathering trend. Our laboratory results were compared with published colours of TNOs and Centaurs. A broad variety of spectral colours observed for TNOs and Centaurs may be reproduced by various spectra of irradiated organics corresponding to different ion fluences. However, such objects probably also contain ices and silicate components which show different space weathering trends. This fact, together with a lack of information about albedos, may explain difficulties to reveal correlations between surface colours within TNO and Centaur populations and their other properties, such as absolute magnitudes and orbital parameters.

  12. Ultraviolet photolysis studies on XeO4 in noble-gas and F2 matrices and the formation and characterization of a new Xe(VIII) oxide, (?(2) -O2 )XeO3.

    PubMed

    Vent-Schmidt, Thomas; Goettel, James T; Schrobilgen, Gary J; Riedel, Sebastian

    2015-07-27

    The photolytic behavior of the thermochemically unstable xenon(VIII) oxide XeO4 was investigated by UV irradiation in noble-gas and F2 matrices. Photolysis of Xe(16) O4 or Xe(18) O4 in noble-gas matrices at 365?nm yielded XeO3 and a new xenon(VIII) oxide, namely, (?(2) -O2 )XeO3 , which, along with XeO4 , was characterized by matrix-isolation IR spectroscopy and quantum-chemical calculations. Calculations of the UV spectrum showed that the photodecomposition is induced by an n??* transition, but the nature of the excitation differs when different light sources are used. There is strong evidence for the formation of mobile (1) D excited O atoms in the case of excitation at 365?nm, which led to the formation of (?(2) -O2 )XeO3 by reaction with XeO4 . Matrix-isolation IR spectroscopy in Ne and Ar matrices afforded the natural-abundance xenon isotopic pattern for the ?3 (T2 ) stretching mode of Xe(16) O4 , and (18) O enrichment provided the (16) O/(18) O isotopic shifts of XeO4 and (?(2) -O2 )XeO3 . PMID:26095795

  13. Ion irradiation of the Murchison meteorite: Visible to mid-infrared spectroscopic results

    NASA Astrophysics Data System (ADS)

    Lantz, C.; Brunetto, R.; Barucci, M. A.; Dartois, E.; Duprat, J.; Engrand, C.; Godard, M.; Ledu, D.; Quirico, E.

    2015-05-01

    Aims: The goal of this study is to simulate space weathering processes on primitive bodies. We use ion implantation as a simulation of solar wind irradiation, which has been suggested by several authors to be the major component of space weathering on main belt asteroids. The laboratory analogs we irradiate and analyze are carbonaceous chondrites; we started the study with the Allende CV meteorite and in this companion paper we present results on the Murchison CM meteorite. Methods: We performed irradiations on pressed pellets of Murchison with 40 keV He+ and Ar+ ions using fluences up to 3 × 1016 ions/cm2. Reflectance spectra were acquired ex situ before and after irradiation in the visible to mid-infrared range (0.4-16 ?m). A Raman analysis was also performed to investigate the modifications of the aromatic carbonaceous component. Results: Our results indicate that spectral variations after irradiation within the visible range are smaller than spectral variations due to sample grain size or viewing geometry of the Murchison meteorite. The aqueous alteration band profile near 3 ?m changes after irradiation, as adsorbed water is removed, and phyllosilicates are affected. Raman spectroscopy highlights the insoluble organic matter (IOM) modification under irradiation. We observe a shift of the silicates band at 9.9 ?m, probably due to a preferential loss of Mg (compared to Fe, the lighter Mg is more easily sputtered backward) and/or amorphization of Mg-rich materials. We compare our results to previous experiments on organic-rich materials (like asphaltite or carbonaceous chondrites), and on ordinary chondrites and olivine grains. We find that the reddening/darkening trend observed on silicate-rich surfaces is not valid for all carbonaceous chondrites, and that the spectral modifications after irradiation are a function of the initial albedo.

  14. Microstructural evolution of CANDU spacer material Inconel X-750 under in situ ion irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, He Ken; Yao, Zhongwen; Judge, Colin; Griffiths, Malcolm

    2013-11-01

    Work on Inconel®Inconel® is a registered trademark of Special Metals Corporation that refers to a family of austenitic nickel-chromium-based superalloys.1 X-750 spacers removed from CANDU®CANDU® is a registered trademark of Atomic Energy of Canada Limited standing for ''CANada Deuterium Uranium''.2 reactors has shown that they become embrittled and there is development of many small cavities within the metal matrix and along grain boundaries. In order to emulate the neutron irradiation induced microstructural changes, heavy ion irradiations (1 MeV Kr2+ ions) were performed while observing the damage evolution using an intermediate voltage electron microscope (IVEM) operating at 200 kV. The irradiations were carried out at various temperatures 60-400 °C. The principal strengthening phase, ??, was disordered at low doses (˜0.06 dpa) during the irradiation. M23C6 carbides were found to be stable up to 5.4 dpa. Lattice defects consisted mostly of stacking fault tetrahedras (SFTs), 1/2<1 1 0> perfect loops and small 1/3<1 1 1> faulted Frank loops. The ratio of SFT number density to loop number density for each irradiation condition was found to be neither temperature nor dose dependent. Under the operation of the ion beam the SFT production was very rapid, with no evidence for further growth once formed, indicating that they probably formed as a result of cascade collapse in a single cascade. The number density of the defects was found to saturate at low dose (˜0.68 dpa). No cavities were observed regardless of the irradiation temperature between 60 °C and 400 °C for doses up to 5.4 dpa. In contrast, cavities have been observed after neutron irradiation in the same material at similar doses and temperatures indicating that helium, produce during neutron irradiation, may be essential for the nucleation and growth of cavities.

  15. Synthesis of cobalt nanoparticles on Si (100) by swift heavy ion irradiation.

    PubMed

    Attri, Asha; Kumar, Ajit; Verma, Shammi; Ojha, Sunil; Asokan, Kandasami; Nair, Lekha

    2013-01-01

    We report the growth and characterization of uniform-sized nanoparticles of cobalt on n-type silicon (100) substrates by swift heavy ion (SHI) irradiation. The Co thin films of 25-nm thicknesses were grown by e-beam evaporation and irradiated with two different types of ions, 45-MeV Li3+ and 100-MeV O7+ ions with fluences ranging from 1 × 1011 to 1 × 1013 ions/cm2. SHI irradiation, with the beam rastered over the area of the film, resulted in the restructuring of the film into a dense array of Co nanostructures. Surface topography studied by atomic force microscopy revealed narrowed size distributions, with particle sizes ranging from 20 to 50 nm, formed through a self-organized process. Ion fluence-dependent changes in crystallinity of the Co nanostructures were determined by glancing angle X-ray diffraction. Rutherford backscattering spectroscopy analysis showed the absence of beam-induced mixing in this system. Surface restructuring and beam-induced crystallization are the dominant effects, with the nanoparticle size and density being dependent on the ion fluence. Results are analyzed in the context of molecular dynamics calculations of electron-lattice energy transfer. PMID:24138985

  16. Effect of low energy oxygen ion beam irradiation on ionic conductivity of solid polymer electrolyte

    SciTech Connect

    Manjunatha, H. Kumaraswamy, G. N.; Damle, R.

    2014-04-24

    Over the past three decades, solid polymer electrolytes (SPEs) have drawn significant attention of researchers due to their prospective commercial applications in high energy-density batteries, electrochemical sensors and super-capacitors. The optimum conductivity required for such applications is about 10{sup ?2} – 10{sup ?4} S/cm, which is hard to achieve in these systems. It is known that the increase in the concentration of salt in the host polymer results in a continuous increase in the ionic conductivity. However, there is a critical concentration of the salt beyond which the conductivity decreases due to formation of ion pairs with no net charge. In the present study, an attempt is made to identify the concentration at which ion pair formation occurs in PEO: RbBr. We have attempted to modify microstructure of the host polymer matrix by low energy ion (Oxygen ion, O{sup +1} with energy 100 keV) irradiation. Ionic conductivity measurements in these systems were carried out using Impedance Spectroscopy before and after irradiation to different fluencies of the oxygen ion. It is observed that the conductivity increases by one order in magnitude. The increase in ionic conductivity may be attributed to the enhanced segmental motion of the polymer chains. The study reveals the importance of ion irradiation as an effective tool to enhance conductivity in SPEs.

  17. Thermal stability of embedded metal nanoparticles elongated by swift heavy ion irradiation: Zn nanoparticles in a molten state but preserving elongated shapes.

    PubMed

    Amekura, Hiro; Sele, Marta Lill; Ishikawa, Norito; Okubo, Nariaki

    2012-03-01

    Solid Zn and V nanoparticles (NPs) embedded in silica were elongated by swift heavy ion (SHI) irradiation with 200 MeV Xe(14+) ions to a fluence of 5.0 × 10(13) ions cm(-2). Isochronal annealing was carried out in a vacuum from 200 to 1000 °C in steps of 100 °C for 10 min each. The degree of shape elongation was evaluated at room temperature (RT) by two different optical methods: linear dichroism spectroscopy and birefringence spectroscopy. In the as-irradiated state, the samples showed an absorption band at 5 eV due to radiation-induced defects in the silica in addition to the anisotropic absorption due to the elongated metal NPs. After annealing at 400 °C the defect band had completely disappeared, while the degree of shape elongation was almost unchanged or rather slightly increased in both the Zn and V NPs. The elongation of the Zn NPs slightly decreased but maintained a certain value after annealing at 500 °C, which is much higher than the melting point (MP) of Zn NPs (~420 °C). This observation indicates that shape elongation is mostly maintained even if the Zn NPs are in the molten state to some extent during annealing. The elongation of the Zn NPs was almost eliminated after annealing at 600 °C. In the case of the V NPs, elongation was maintained up to 800 °C but mostly eliminated at 900 °C. Since the recovery temperature of 900 °C from the elongated to the spherical shape is much lower than the MP of bulk V (1890 °C), we consider that the elongation is eliminated without melting of V NPs, i.e. via solid state mass transportation. The melting of NPs is not the key factor for the recovery to the spherical shape. PMID:22322542

  18. Ion irradiation of Fe-Fe oxide core-shell nanocluster films: Effect of interface on stability of magnetic properties

    SciTech Connect

    McCloy, John S.; Jiang, Weilin; Droubay, Timothy C.; Varga, Tamas; Kovarik, Libor; Sundararajan, Jennifer A.; Kaur, Maninder; Qiang, You; Burks, Edward; Liu, Kai

    2013-08-23

    A cluster deposition method was used to produce films of loosely aggregated nanoclusters (NC) of Fe core-Fe3O4 shell or fully oxidized Fe3O4. Films of these NC on Si(100) or MgO(100)/Fe3O4(100) were irradiated to 1016 Si2+/cm2 near room temperature using an ion accelerator. Ion irradiation creates structural change in the NC film with corresponding chemical and magnetic changes which depend on the initial oxidation state of the cluster. Films were characterized using magnetometry (hysteresis, first order reversal curves), microscopy (transmission electron, helium ion), and x-ray diffraction. In all cases, the particle sizes increased due to ion irradiation, and when a core of Fe is present, irradiation reduces the oxide shells to lower valent Fe species. These results show that ion irradiated behavior of the nanocluster films depends strongly on the initial nanostructure and chemistry, but in general saturation magnetization decreases slightly.

  19. Atomistic modeling of nanoscale patterning of L1{sub 2} order induced by ion irradiation

    SciTech Connect

    Ye Jia; Li Youhong; Averback, Robert; Zuo Jianmin; Bellon, Pascal

    2010-09-15

    Theoretical predictions indicate that ordered alloys can spontaneously develop a steady-state nanoscale microstructure when irradiated with energetic particles. This behavior derives from a dynamical competition between disordering in cascades and thermally activated reordering, which leads to self-organization of the chemical order parameter. We test this possibility by combining molecular dynamics (MD) and kinetic Monte Carlo (KMC) simulations. We first generate realistic distributions of disordered zones for Ni{sub 3}Al irradiated with 70 keV He and 1 MeV Kr ions using MD and then input this data into KMC to obtain predictions of steady state microstructures as a function of the irradiation flux. Nanoscale patterning is observed for Kr ion irradiations but not for He ion irradiations. We illustrate, moreover, using image simulations of these KMC microstructures, that high-resolution transmission electron microscopy can be employed to identify nanoscale patterning. Finally, we indicate how this method could be used to synthesize functional thin films, with potential for magnetic applications.

  20. Microstructure and Cs Behavior of Ba-Doped Aluminosilicate Pollucite Irradiated with F+ Ions

    SciTech Connect

    Jiang, Weilin; Kovarik, Libor; Zhu, Zihua; Varga, Tamas; Engelhard, Mark H.; Bowden, Mark E.; Nenoff, Tina M.; Garino, Terry

    2014-08-07

    Radionuclide 137Cs is one of the major fission products that dominate heat generation in spent fuels over the first 300 hundred years. A durable waste form for 137Cs that decays to 137Ba is needed to minimize its environmental impact. Aluminosilicate pollucite CsAlSi2O6 is selected as a model waste form to study the decay-induced structural effects. While Ba-containing precipitates are not present in charge-balanced Cs0.9Ba0.05AlSi2O6, they are found in Cs0.9Ba0.1AlSi2O6 and identified as monoclinic Ba2Si3O8. Pollucite is susceptible to electron irradiation induced amorphization. The threshold density of the electronic energy deposition for amorphization is determined to be ~235 keV/nm3. Pollucite can be readily amorphized under F+ ion irradiation at 673 K. A significant amount of Cs diffusion and release from the amorphized pollucite is observed during the irradiation. However, cesium is immobile in the crystalline structure under He+ ion irradiation at room temperature. The critical temperature for amorphization is not higher than 873 K under F+ ion irradiation. If kept at or above 873 K all the time, the pollucite structure is unlikely to be amorphized; Cs diffusion and release are improbable. A general discussion regarding pollucite as a potential waste form is provided in this report.

  1. Amorphization and reduction of thermal conductivity in porous silicon by irradiation with swift heavy ions

    NASA Astrophysics Data System (ADS)

    Newby, Pascal J.; Canut, Bruno; Bluet, Jean-Marie; Gomès, Séverine; Isaiev, Mykola; Burbelo, Roman; Termentzidis, Konstantinos; Chantrenne, Patrice; Fréchette, Luc G.; Lysenko, Vladimir

    2013-07-01

    In this article, we demonstrate that the thermal conductivity of nanostructured porous silicon is reduced by amorphization and also that this amorphous phase in porous silicon can be created by swift (high-energy) heavy ion irradiation. Porous silicon samples with 41%-75% porosity are irradiated with 110 MeV uranium ions at six different fluences. Structural characterisation by micro-Raman spectroscopy and SEM imaging show that swift heavy ion irradiation causes the creation of an amorphous phase in porous Si but without suppressing its porous structure. We demonstrate that the amorphization of porous silicon is caused by electronic-regime interactions, which is the first time such an effect is obtained in crystalline silicon with single-ion species. Furthermore, the impact on the thermal conductivity of porous silicon is studied by micro-Raman spectroscopy and scanning thermal microscopy. The creation of an amorphous phase in porous silicon leads to a reduction of its thermal conductivity, up to a factor of 3 compared to the non-irradiated sample. Therefore, this technique could be used to enhance the thermal insulation properties of porous Si. Finally, we show that this treatment can be combined with pre-oxidation at 300 °C, which is known to lower the thermal conductivity of porous Si, in order to obtain an even greater reduction.

  2. Submitted for publication Production of defects in supported carbon nanotubes under ion irradiation

    E-print Network

    Nordlund, Kai

    revealed a broad range of new inter- esting phenomena. These are, e.g., the coalescence 2 and welding 3 as masks. 10 By irradiating with 300 eV Ar + ions, a Au/Ti wire a few nanometers in width has been formed

  3. Switching of the natural nanostructure in Bi2Te3 materials by ion irradiation.

    PubMed

    Aabdin, Zainul; Peranio, Nicola; Eibl, Oliver

    2012-09-01

    In Bi(2)Te(3) materials the natural nanostructure (nns) with a wavelength of 10 nm can be reproducibly switched ON and OFF by Ar(+) ion irradiation at 1.5 and 1 keV. Controlled formation of the nns in Bi(2)Te(3) materials has potential for reducing its thermal conductivity and could increase the thermoelectric figure of merit. PMID:22718358

  4. Carbon Ion Irradiation Inhibits Glioma Cell Migration Through Downregulation of Integrin Expression

    SciTech Connect

    Rieken, Stefan; Habermehl, Daniel; Wuerth, Lena; Brons, Stephan; Mohr, Angela; Lindel, Katja; Weber, Klaus; Haberer, Thomas; Debus, Juergen; Combs, Stephanie E.

    2012-05-01

    Purpose: To investigate the effect of carbon ion irradiation on glioma cell migration. Methods and Materials: U87 and Ln229 glioma cells were irradiated with photons and carbon ions. Migration was analyzed 24 h after irradiation. Fluorescence-activated cell sorting analysis was performed in order to quantify surface expression of integrins. Results: Single photon doses of 2 Gy and 10 Gy enhanced {alpha}{sub {nu}}{beta}{sub 3} and {alpha}{sub {nu}}{beta}{sub 5} integrin expression and caused tumor cell hypermigration on both vitronectin (Vn) and fibronectin (Fn). Compared to integrin expression in unirradiated cells, carbon ion irradiation caused decreased integrin expression and inhibited cell migration on both Vn and Fn. Conclusion: Photon radiotherapy (RT) enhances the risk of tumor cell migration and subsequently promotes locoregional spread via photon induction of integrin expression. In contrast to photon RT, carbon ion RT causes decreased integrin expression and suppresses glioma cell migration on both Vn and Fn, thus promising improved local control.

  5. Nanoscale manipulation of Ge nanowires by ion irradiation Lucia Romano,1,a

    E-print Network

    Florida, University of

    Nanoscale manipulation of Ge nanowires by ion irradiation Lucia Romano,1,a Nicholas G. Rudawski,2,b and electromechanical devices. However, in many cases, manipulation and modification of nanowires are required to fully direction. This effect demonstrates the detailed manipulation of nanoscale structures is possible through

  6. Amorphization and reduction of thermal conductivity in porous silicon by irradiation with swift heavy ions

    SciTech Connect

    Newby, Pascal J.; Canut, Bruno; Bluet, Jean-Marie; Lysenko, Vladimir; Gomes, Severine; Isaiev, Mykola; Burbelo, Roman; Chantrenne, Patrice; Frechette, Luc G.

    2013-07-07

    In this article, we demonstrate that the thermal conductivity of nanostructured porous silicon is reduced by amorphization and also that this amorphous phase in porous silicon can be created by swift (high-energy) heavy ion irradiation. Porous silicon samples with 41%-75% porosity are irradiated with 110 MeV uranium ions at six different fluences. Structural characterisation by micro-Raman spectroscopy and SEM imaging show that swift heavy ion irradiation causes the creation of an amorphous phase in porous Si but without suppressing its porous structure. We demonstrate that the amorphization of porous silicon is caused by electronic-regime interactions, which is the first time such an effect is obtained in crystalline silicon with single-ion species. Furthermore, the impact on the thermal conductivity of porous silicon is studied by micro-Raman spectroscopy and scanning thermal microscopy. The creation of an amorphous phase in porous silicon leads to a reduction of its thermal conductivity, up to a factor of 3 compared to the non-irradiated sample. Therefore, this technique could be used to enhance the thermal insulation properties of porous Si. Finally, we show that this treatment can be combined with pre-oxidation at 300 Degree-Sign C, which is known to lower the thermal conductivity of porous Si, in order to obtain an even greater reduction.

  7. In situ ion irradiation of zirconium carbide Christopher J. Ulmer a, *

    E-print Network

    Motta, Arthur T.

    as the load-bearing layer in TRISO fuel for a VHTR, the response of ZrC to radiation damage must be understood Accepted 5 August 2015 Available online 10 August 2015 Keywords: Nuclear materials Zirconium carbide Ion irradiation Defects a b s t r a c t Zirconium carbide (ZrC) is a candidate material for use in one

  8. In-situ Study of Nanostructure and Electrical Resistance of Nanocluster Films Irradiated with Ion Beams

    SciTech Connect

    Jiang, Weilin; Sundararajan, Jennifer A.; Varga, Tamas; Bowden, Mark E.; Qiang, You; McCloy, John S.; Henager, Charles H.; Montgomery, Robert O.

    2014-08-11

    An in-situ study is reported on the structural evolution in nanocluster films under He+ ion irradiation using an advanced helium ion microscope. The films consist of loosely interconnected nanoclusters of magnetite or iron-magnetite (Fe-Fe3O4) core-shells. The nanostructure is observed to undergo dramatic changes under ion-beam irradiation, featuring grain growth, phase transition, particle aggregation, and formation of nanowire-like network and nano-pores. Studies based on ion irradiation, thermal annealing and election irradiation have indicated that the major structural evolution is activated by elastic nuclear collisions, while both electronic and thermal processes can play a significant role once the evolution starts. The electrical resistance of the Fe-Fe3O4 films measured in situ exhibits a super-exponential decay with dose. The behavior suggests that the nanocluster films possess an intrinsic merit for development of an advanced online monitor for neutron radiation with both high detection sensitivity and long-term applicability, which can enhance safety measures in many nuclear operations.

  9. In Situ Transmission Electron Microscopy and Ion Irradiation of Ferritic Materials

    E-print Network

    Motta, Arthur T.

    In Situ Transmission Electron Microscopy and Ion Irradiation of Ferritic Materials MARQUIS A. KIRK The intermediate voltage electron microscope-tandem user facility in the Electron Microscopy Center at Argonne National Laboratory is described. The primary purpose of this facil- ity is electron microscopy

  10. Helium ion irradiation behavior of Ni-1wt.%SiCNP composite and the effect of ion flux

    NASA Astrophysics Data System (ADS)

    Zhou, X. L.; Huang, H. F.; Xie, R.; Thorogood, G. J.; Yang, C.; Li, Z. J.; Xu, H. J.

    2015-12-01

    Silicon carbide nanoparticle-reinforced nickel metal (Ni-SiCNP composite) samples were bombarded by helium ions with fluences of 1 × 1016 and 3 × 1016 ions/cm2 at two different fluxes. The microstructural and mechanical changes were characterized via TEM and nanoindentation. Nano-scaled helium bubbles in the shape of spheres were observed in the samples irradiated at high flux and polygons at low flux. The number of helium bubbles increased with the fluence, whereas their mean size remained unaffected. In addition, the nanohardness of the damage layer also increased as the fluence increased. In addition this study suggests that a higher flux results in a higher number of smaller helium bubbles, while showing no obvious effect on the irradiation-induced hardening of the materials.

  11. Effects of heavy-ion irradiations in K-doped BaFe2As2

    NASA Astrophysics Data System (ADS)

    Ohtake, F.; Taen, T.; Pyon, S.; Tamegai, T.; Okayasu, S.; Kambara, T.; Kitamura, H.

    2015-11-01

    We report the effects of heavy-ion irradiation in (Ba0.6K0.4)Fe2As2 single crystals including its dose dependence. We found that the suppression of Tc is weak up to a certain dose of irradiation. Critical current density (Jc) under self-field is strongly enhanced up to 15 MA cm-2 at 2 K by the introduction of defects through irradiations with different energies and ion species. This upper limit is in agreement with the previous report for that in cuprate superconductors. The dose dependence of Jc follows B?1/2, which can be explained by the simple scenario on the interaction between a driven vortex and discontinuous columnar defects.

  12. In situ transmission electron microscopy and ion irradiation of ferritic materials.

    PubMed

    Kirk, Marquis A; Baldo, Peter M; Liu, Amelia C Y; Ryan, Edward A; Birtcher, Robert C; Yao, Zhongwen; Xu, Sen; Jenkins, Michael L; Hernandez-Mayoral, Mercedes; Kaoumi, Djamel; Motta, Arthur T

    2009-03-01

    The intermediate voltage electron microscope-tandem user facility in the Electron Microscopy Center at Argonne National Laboratory is described. The primary purpose of this facility is electron microscopy with in situ ion irradiation at controlled sample temperatures. To illustrate its capabilities and advantages a few results of two outside user projects are presented. The motion of dislocation loops formed during ion irradiation is illustrated in video data that reveals a striking reduction of motion in Fe-8%Cr over that in pure Fe. The development of extended defect structure is then shown to depend on this motion and the influence of nearby surfaces in the transmission electron microscopy thin samples. In a second project, the damage microstructure is followed to high dose (200 dpa) in an oxide dispersion strengthened ferritic alloy at 500 degrees C, and found to be qualitatively similar to that observed in the same alloy neutron irradiated at 420 degrees C. PMID:19189372

  13. Swift heavy-ion irradiated active waveguides in Nd:YAG crystals: fabrication and laser generation.

    PubMed

    Ren, Yingying; Dong, Ningning; Chen, Feng; Benayas, A; Jaque, D; Qiu, Feng; Narusawa, Tadashi

    2010-10-01

    An Nd:YAG planar waveguide laser has been fabricated by ultra-low-fluence (2×10(12) cm(-2)) swift heavy-ion irradiation (60 MeV Ar(4+) ions). The appearance of the buried waveguiding has been associated with an increased refractive index layer as a consequence of the ion-induced electronic damage. Continuous-wave laser oscillations at 1064.2 nm have been observed from the waveguide under 808 nm optical excitation, with the absorbed pump power at threshold and laser slope efficiency close to 26 mW and 5.9%, respectively. PMID:20890358

  14. Iron ion irradiation increases promotes adhesion of monocytic cells to arterial vascular endothelium

    NASA Astrophysics Data System (ADS)

    Kucik, Dennis; Khaled, Saman; Gupta, Kiran; Wu, Xing; Yu, Tao; Chang, Polly; Kabarowski, Janusz

    Radiation causes inflammation, and chronic, low-level vascular inflammation is a risk factor for atherosclerosis. Consistent with this, exposure to radiation from a variety of sources is associated with increased risk of heart disease and stroke. Part of the inflammatory response to radiation is a change in the adhesiveness of the endothelial cells that line the blood vessels, triggering inappropriate accumulation of leukocytes, leading to later, damaging effects of inflammation. Although some studies have been done on the effects of gamma irradiation on vascular endothelium, the response of endothelium to heavy ion radiation likely to be encountered in prolonged space flight has not been determined. We investigated how irradiation of aortic endothelial cells with iron ions affects adhesiveness of cultured aortic endothelial cells for monocytic cells and the consequences of this for development of atherosclerosis. Aortic endothelial cells were irradiated with 600 MeV iron ions at Brookhaven National Laboratory and adhesion-related changes were measured. Cells remained viable for at least 72 hours, and were even able to repair acute damage to cell junctions. We found that iron ion irradiation altered expression levels of specific endothelial cell adhesion molecules. Further, these changes had functional consequences. Using a flow chamber adhesion assay to measure adhesion of monocytic cells to endothelial cells under physiological shear stress, we found that adhesivity of vascular endothelium was enhanced in as little as 24 hours after irradiation. Further, the radiation dose dependence was not monotonic, suggesting that it was not simply the result of endothelial cell damage. We also irradiated aortic arches and carotid arteries of Apolipoprotein-E-deficient mice. Histologic analysis of these mice will be conducted to determine whether effects of radiation on endothelial adhesiveness result in consequences for development of atherosclerosis. (Supported by NSBRI: NCC-9-58-162)

  15. Swift heavy ion irradiation induced enhancement in the antioxidant activity and biocompatibility of polyaniline nanofibers

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Banerjee, Somik; Saikia, Jyoti P.; Konwar, B. K.

    2010-04-01

    Polyaniline (PAni) nanofibers doped with HCl and CSA have been irradiated with 90 MeV O7 + ions with fluence of 3 × 1010, 3 × 1011 and 1 × 1012 ions cm - 2. TEM micrographs show a decrease in the fiber diameter with increasing irradiation fluence, which has been explained on the basis of the Coulomb explosion model. XRD analysis reveals a decrease in the crystalline domain length and an increase in the strain. The increase in d-spacing for the (100) reflection with increasing irradiation fluence is ascribed to the increase in the tilt angle of the polymer chain, which is also evident from micro-Raman spectra. UV-vis spectra of the PAni nanofibers exhibit blue-shift in the absorption bands attributed to ?-?* band transitions indicating a reduction in particle size after SHI irradiation; as also observed in TEM micrographs. Micro-Raman spectra also reveal a transition from the benzenoid to quinoid structures in the PAni chain as the fluence is increased. Although the quinoid unit has no hydrogen for DPPH scavenging, the antioxidant activity of PAni nanofibers is found to increase with increasing fluence. This has been attributed to the availability of more reaction sites as a result of fragmentation of the PAni nanofibers which compensates for the benzenoid to quinoid transition after irradiation. The biocompatibility of the PAni nanofibers is also found to increase with increasing irradiation fluence, indicating the possibility of employing swift heavy ion irradiation as an effective technique in order to modify conducting polymer nanostructures for biomedical applications.

  16. 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.

  17. Amorphization and recrystallization of single-crystalline hydrogen titanate nanowires by N{sup +} ion irradiation

    SciTech Connect

    Behera, Akshaya K.; Bandyopadyay, Malay K.; Chatterjee, Shyamal; Facsko, Stefan; Das, Siddhartha

    2014-06-21

    We report on the phase transformation of hydrogen titanate (H{sub 2}Ti{sub 3}O{sub 7}) nanowires induced by 50?keV N{sup +} ion irradiation at room temperature with fluences of 1?×?10{sup 15} ions/cm{sup 2} and 1?×?10{sup 16} ions/cm{sup 2}, respectively. Using transmission electron microscopy, the internal structure of the ion irradiated nanowires is analyzed. At low fluence, a transformation from crystalline H{sub 2}Ti{sub 3}O{sub 7} to amorphous TiO{sub 2} is observed. However, at higher fluence, a remarkable crystalline-amorphous TiO{sub 2} core-shell structure is formed. At this higher fluence, the recrystallization occurs in the core of the nanowire and the outer layer remains amorphous. The phase transformation and formation of core-shell structure are explained using the thermal spike model, radiation enhanced diffusion, and classical theory of nucleation and growth under non-equilibrium thermodynamics. X-ray photoelectron spectroscopy and Raman scattering reveal further insight into the structure of the nanowires before and after ion irradiation.

  18. Formation and evolution of ripples on ion-irradiated semiconductor surfaces

    SciTech Connect

    Kang, M.; Wu, J. H.; Ye, W.; Jiang, Y.; Robb, E. A.; Chen, C.; Goldman, R. S.

    2014-02-03

    We have examined the formation and evolution of ripples on focused-ion-beam (FIB) irradiated compound semiconductor surfaces. Using initially normal-incidence Ga{sup +} FIB irradiation of InSb, we tuned the local beam incidence angle (?{sub eff}) by varying the pitch and/or dwell time. For single-pass FIB irradiation, increasing ?{sub eff} induces morphological evolution from pits and islands to ripples to featureless surfaces. Multiple-pass FIB irradiation of the rippled surfaces at a fixed ?{sub eff} leads to island formation on the ripple crests, followed by nanorod (NR) growth. This ripple-NR transition provides an alternative approach for achieving dense arrays of NRs.

  19. Expansion and melting of Xe nanocrystals in Si

    SciTech Connect

    Faraci, Giuseppe; Pennisi, Agata R.; Zontone, Federico; Li, Boquan; Petrov, Ivan

    2006-12-15

    Xe agglomerates confined in a Si matrix by ion implantation were synthesized with different size depending on the implantation process and/or the thermal treatment. At low temperature Xe nanocrystals are formed, whose expansion and melting were studied in the range 15-300 K. Previous high resolution x-ray diffraction spectra were corroborated with complementary techniques such as two-dimensional imaging plate patterns and transmission electron microscopy. We detected fcc Xe nanocrystals whose properties were size dependent. The experiments showed that in annealed samples epitaxial condensation of small Xe clusters, on the cavities of the Si matrix, gave in fact expanded and oriented Xe, suggesting a possible preferential growth of Xe (311) planes oriented orthogonally to the Si[02-2] direction. On the contrary, small Xe clusters in an amorphous Si matrix have a fcc lattice contracted as a consequence of surface tension. Furthermore, a solid-to-liquid phase transition size dependent was found. Expansion of fcc Xe lattice was accurately determined as a function of the temperature. Overpressurized nanocrystals and/or binary size distributions were disproved.

  20. Swift carbon ion irradiated Nd:YAG ceramic optical waveguide amplifier.

    PubMed

    Tan, Yang; Luan, Qingfang; Liu, Fengqin; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng

    2013-06-17

    A high-gain optical waveguide amplifier has been realized in a channel waveguide platform of Nd:YAG ceramic produced by swift carbon ion irradiation with metal masking. The waveguide is single mode at wavelength of 810 and 1064 nm, and with the enhanced fluorescence intensity at around 1064 nm due to the Nd(3+) ion emissions. In conjunction with the low propagation loss of the waveguide, about 26.3 dB/cm of the small signal gain at 1064 nm is achieved with an 18 ns pulse laser as the seeder under the 810-nm laser excitation. This work suggests the carbon ion irradiated Nd:YAG waveguides could serve as efficient integrated amplifiers for the signal amplification. PMID:23787589

  1. Irradiation damage of uridine molecules with MeV heavy ions

    NASA Astrophysics Data System (ADS)

    Xue, Jianming; Xie, Yanbo; Chen, Long; Jing, Ke; Wang, Yugang

    2009-03-01

    In order to study the mechanism of the nucleotide directly damaged by energetic heavy ions, the residual ratio of uridine molecules after irradiation was measured by means of High Performance Liquid Chromatography (HPLC). The experimental results show that the irradiation damage probability depends on the electronic energy loss rate ( S e) of incident ions: first it increases quickly with S e, then becomes stable when S e reaches 800 eV/nm. The contribution of the nuclear collisions can be neglected compared with that of the electronic process. This is not only because that the nuclear energy loss rate ( S n) is much smaller than S e for MeV heavy ions, but also because the energy deposition through the electronic process is more efficient in damaging molecules than through the nuclear process.

  2. Mechanisms of nanorod growth on focused-ion-beam-irradiated semiconductor surfaces: Role of redeposition

    SciTech Connect

    Wu, J. H.; Goldman, R. S.

    2012-01-30

    We have examined the formation and evolution of irradiation-induced nanorod (NR) growth through a comparison of focused-ion-beam irradiation of InSb wafers and InSb/GaAs heterostructures. Above a critical ion dose, cone-shaped NRs capped with In islands form on both InSb surfaces. For InSb wafers, the NR base diameter increases with ion energy. In the case of InSb/GaAs heterostructures, as the milled depth approaches the InSb/GaAs interface, the cone-shaped NRs transition to capless NRs with a truncated cone shape. These results suggest a growth mechanism in which both the NR cap and body are supplied by redeposition of atoms sputtered from InSb.

  3. The kinetics of point defects in metals under ion irradiation

    NASA Astrophysics Data System (ADS)

    Avdeeva, A. V.

    2015-11-01

    Modeling an irradiation process of a copper plate for studying the formation and evolution of point defects, that are vacancies and interstitials, is presented in this work. The point defects formation energies were estimated for fcc Cu using molecular dynamics simulation. These values were applied at calculations of atomic concentrations of vacancies and interstitials by numerically decision of kinetic equations. The results of molecular dynamics simulation showed that the interstitial formation energy is more than the vacancy formation energy. These values are in satisfactory agreement with the experimental data. The results of calculations of atomic concentrations of defects confirmed that interstitials are more mobile and their absorption by stocks is more intense.

  4. Temporal evolution of nanoporous layer in off-normally ion irradiated GaSb

    SciTech Connect

    Datta, D. P.; Garg, S. K.; Som, T.; Kanjilal, A.; Sahoo, P. K.; Kanjilal, D.

    2014-03-28

    Room temperature irradiation of GaSb by 60?keV Ar{sup +}-ions at an oblique incidence of 60° leads to simultaneous formation of a nanoporous layer and undulations at the interface with the underlying substrate. Interestingly, with increasing ion fluence, a gradual embedding of the dense nanoporous layer takes place below ridge-like structures (up to the fluence of 1?×?10{sup 17} ions cm{sup ?2}), which get extended to form a continuous layer (at fluences ?4?×?10{sup 17} ions cm{sup ?2}). Systematic compositional analyses reveal the co-existence of Ga{sub 2}O{sub 3} and Sb{sub 2}O{sub 3} in the surface layer. The results are discussed in terms of a competition between ion-induced defect accumulation and re-deposition of sputtered atoms on the surface.

  5. Effects of high energy Au-ion irradiation on the microstructure of diamond films

    SciTech Connect

    Chen, Shih-Show; Chen, Huang-Chin; Wang, Wei-Cheng; Lin, I-Nan; Chang, Ching-Lin; Lee, Chi-Young; Guo Jinghua

    2013-03-21

    The effects of 2.245 GeV Au-ion irradiation and subsequent annealing processes on the evolution of microstructure of diamond films with microcrystalline (MCD) or ultra-nanocrystalline (UNCD) granular structure were investigated, using near edge x-ray absorption fine structure and electron energy loss spectroscopy in transmission electron microscopy. For MCD films, the Au-ion irradiation disintegrated some of the diamond grains, resulting in the formation of nano-sized carbon clusters embedded in a matrix of amorphous carbon (a-C). The annealing process recrystallized the diamond grains and converted the a-C into nano-sized graphite particulates and, at the same time, induced the formation of nano-sized i-carbon clusters, the bcc structured carbon with a{sub 0} = 0.432 nm. In contrast, for UNCD films, the Au-ion irradiation transformed the grain boundary phase into nano-sized graphite, but insignificantly altered the crystallinity of the grains of the UNCD films. The annealing process recrystallized the materials. In some of the regions, the residual a-C phases were transformed into nano-sized graphites, whereas in other regions i-carbon nanoclusters were formed. The difference in irradiation-induced microstructural transformation behavior between the MCD and the UNCD films is ascribed to the different granular structures of the two types of films.

  6. Effects of high energy Au-ion irradiation on the microstructure of diamond films

    NASA Astrophysics Data System (ADS)

    Chen, Shih-Show; Chen, Huang-Chin; Wang, Wei-Cheng; Lee, Chi-Young; Lin, I.-Nan; Guo, Jinghua; Chang, Ching-Lin

    2013-03-01

    The effects of 2.245 GeV Au-ion irradiation and subsequent annealing processes on the evolution of microstructure of diamond films with microcrystalline (MCD) or ultra-nanocrystalline (UNCD) granular structure were investigated, using near edge x-ray absorption fine structure and electron energy loss spectroscopy in transmission electron microscopy. For MCD films, the Au-ion irradiation disintegrated some of the diamond grains, resulting in the formation of nano-sized carbon clusters embedded in a matrix of amorphous carbon (a-C). The annealing process recrystallized the diamond grains and converted the a-C into nano-sized graphite particulates and, at the same time, induced the formation of nano-sized i-carbon clusters, the bcc structured carbon with a0 = 0.432 nm. In contrast, for UNCD films, the Au-ion irradiation transformed the grain boundary phase into nano-sized graphite, but insignificantly altered the crystallinity of the grains of the UNCD films. The annealing process recrystallized the materials. In some of the regions, the residual a-C phases were transformed into nano-sized graphites, whereas in other regions i-carbon nanoclusters were formed. The difference in irradiation-induced microstructural transformation behavior between the MCD and the UNCD films is ascribed to the different granular structures of the two types of films.

  7. Mechanical response of UO2 single crystals submitted to low-energy ion irradiation

    NASA Astrophysics Data System (ADS)

    Nguyen, Tien-Hien; Debelle, Aurélien; Boulle, Alexandre; Garrido, Frédérico; Thomé, Lionel; Demange, Valérie

    2015-12-01

    {111}- and {100}-oriented UO2 single crystals were irradiated with 500-keV Ce3+ ions in the 1014-9 × 1014 cm-2 fluence range. The irradiation-induced strain was monitored using high-resolution X-ray diffraction. A mechanical modelling dedicated to thin irradiated layers was applied to account for the reaction of the unirradiated part of the crystals. The elastic strain, which is confined along the surface normal of the samples, increases with ion fluence until it is dramatically relieved. This behaviour is observed for both orientations. While the measured elastic strain depends on the crystallographic direction, the strain due to irradiation defects only is found to be equal for both directions, with a maximum value of ?0.5%. Strain relaxation takes place at the damage peak, but the in-plane lattice parameter of the irradiated layer remains unchanged and equal to that of the pristine material. Meanwhile, the strain at the damaged/pristine interface continues to increase.

  8. Ion Irradiation of H2-Laden Porous Water-ice Films: Implications for Interstellar Ices

    NASA Astrophysics Data System (ADS)

    Raut, U.; Mitchell, E. H.; Baragiola, R. A.

    2015-10-01

    To understand the effects of cosmic-ray (CR) impacts on interstellar icy grains immersed in H2 gas, we have irradiated porous water-ice films loaded with H2 with 100 keV H+. The ice films were exposed to H2 gas at different pressures following deposition and during irradiation. A net H2 loss is observed during irradiation due to competition between ion-induced sputtering and gas adsorption. The initial H2 loss cross-section, 4(1) × 10-14 cm2, was independent of film thickness, H2, and proton fluxes. In addition to sputtering, irradiation also closes nanopores, trapping H2 in the film with binding that exceeds physical absorption energies. As a result, 2%-7% H2 is retained in the ice following irradiation to high fluences. We find that the trapped H2 concentration increases with decreasing ?, the ratio of ion to H2 fluxes, suggesting that as high as 8% solid H2 can be trapped in interstellar ice by CR or stellar wind impacts.

  9. Microstructure evolution and hardness change in ordered Ni3V intermetallic alloy by energetic ion irradiation

    NASA Astrophysics Data System (ADS)

    Hashimoto, A.; Kaneno, Y.; Semboshi, S.; Yoshizaki, H.; Saitoh, Y.; Okamoto, Y.; Iwase, A.

    2014-11-01

    Ni3V bulk intermetallic compounds with ordered D022 structure were irradiated with 16 MeV Au ions at room temperature. The irradiation induced phase transformation was examined by means of the transmission electron microscope (TEM), the extended X-ray absorption fine structure measurement (EXAFS) and the X-ray diffraction (XRD). We also measured the Vickers hardness for unirradiated and irradiated specimens. The TEM observation shows that by the Au irradiation, the lamellar microstructures and the super lattice spot in diffraction pattern for the unirradiated specimen disappeared. This TEM result as well as the result of XRD and EXAFS measurements means that the intrinsic D022 structure of Ni3V changes into the A1 (fcc) structure which is the lattice structure just below the melting point in the thermal equilibrium phase diagram. The lattice structure change from D022 to A1 (fcc) accompanies a remarkable decrease in Vickers microhardness. The change in crystal structure was discussed in terms of the thermal spike and the sequential atomic displacements induced by the energetic heavy ion irradiation.

  10. Amorphization kinetics of Zr(Cr,Fe)[sub 2] under ion irradiation

    SciTech Connect

    Motta, A.T. . Dept. of Nuclear Engineering); Howe, L.M. . Chalk River Labs.); Okamoto, P.R. )

    1992-12-01

    Thin foils of Zircaloy-4 were irradiated with 350 KeV [sup 40]Ar ions in the dual ion beam/HVEM facility at Argonne National Laboratory at 300--650 K. The irradiation-induced amorphization of the intermetallic precipitates Zr (Cr; Fe)[sub 2] and Zr[sub 2] (Ni, Fe) was studied in-situ. For Zr (Cr, Fe)[sub 2] precipitates the dose-to-amorphization was found to increase exponentially with temperature, with a critical temperature of about 650 K. The amorphization morphology was shown to be homogeneous, with no preferential site for nucleation, in contrast to neutron-irradiation amorphization which started at the precipitate-matrix interface. For Zr[sub 2] (Ni,Fe) precipitates it was found that amorphization occurred at 550 and 600 K, whereas in neutron irradiation no amorphization has been observed at those temperatures. The results are discussed in context of previous neutron and electron irradiations and likely amorphization mechanisms are proposed.

  11. Amorphization kinetics of Zr(Cr,Fe){sub 2} under ion irradiation

    SciTech Connect

    Motta, A.T.; Howe, L.M.; Okamoto, P.R.

    1992-12-01

    Thin foils of Zircaloy-4 were irradiated with 350 KeV {sup 40}Ar ions in the dual ion beam/HVEM facility at Argonne National Laboratory at 300--650 K. The irradiation-induced amorphization of the intermetallic precipitates Zr (Cr; Fe){sub 2} and Zr{sub 2} (Ni, Fe) was studied in-situ. For Zr (Cr, Fe){sub 2} precipitates the dose-to-amorphization was found to increase exponentially with temperature, with a critical temperature of about 650 K. The amorphization morphology was shown to be homogeneous, with no preferential site for nucleation, in contrast to neutron-irradiation amorphization which started at the precipitate-matrix interface. For Zr{sub 2} (Ni,Fe) precipitates it was found that amorphization occurred at 550 and 600 K, whereas in neutron irradiation no amorphization has been observed at those temperatures. The results are discussed in context of previous neutron and electron irradiations and likely amorphization mechanisms are proposed.

  12. Effect of Ar{sup +} ion irradiation on the microstructure of pyrolytic carbon

    SciTech Connect

    Feng, Shanglei; Zhang, Dongsheng; Yang, Xinmei; Xia, Huihao E-mail: zhouxingtai@sinap.ac.cn; Yan, Long; Huai, Ping; Zhou, Xingtai E-mail: zhouxingtai@sinap.ac.cn; Yang, Yingguo; Li, Li; Bai, Shuo

    2015-03-21

    Pyrolytic carbon (PyC) coatings prepared by chemical vapor deposition were irradiated by 300?keV Ar{sup +} ions. Then, atomic force microscopy, synchrotron-based grazing incidence X-ray diffraction, Raman spectroscopy, X-ray photoemission spectroscopy, and transmission electron microscopy were employed to study how Ar{sup +} irradiation affects the microstructure of PyC, including the microstructural damage mechanisms and physics driving these phenomena. The 300?keV Ar{sup +} ion irradiation deteriorated the structure along the c-axis, which increased the interlayer spacing between graphene layers. With increasing irradiation dose, the density of defect states on the surface of PyC coating increases, and the basal planes gradually loses their initial ordering resulting in breaks in the lattice and turbulence at the peak damage dose reaches 1.58 displacement per atom (dpa). Surprisingly, the PyC becomes more textured as it becomes richer in structural defects with increasing irradiation dose.

  13. n-Selective Single Capture Following Xe{sup 18+} And Xe{sup 54+} Impact On Na(3s) And Na*(3p)

    SciTech Connect

    Otranto, S.; Olson, R. E.; Hasan, V. G.; Hoekstra, R.

    2011-06-01

    State selective single charge exchange n-level cross sections are calculated for collisions of Xe18+ and Xe54+ ions with Na(3s) and Na*(3p) over the energy range of 0.1 to 10.0 keV/amu. The CTMC method is used which includes all two-body interactions. Experimental state-selective cross sections and their corresponding transverse momentum spectra for Xe18+ are found to be in reasonable accord with the calculations.

  14. Experimental measurement methods and data on irradiation of functional design materials by helium ions in linear accelerator

    E-print Network

    R. A. Anokhin; V. N. Voyevodin; S. N. Dubnyuk; A. M. Egorov; B. V. Zaitsev; A. F. Kobets; O. P. Ledenyov; K. V. Pavliy; V. V. Ruzhitsky; G. D. Tolstolutskaya

    2013-09-03

    The experimental research on the irradiation of the functional design materials by the Helium ions in the linear accelerator is conducted. The experimental measurements techniques and data on the irradiation of the functional design materials by the Helium ions with the energy up to 4 MeV, including the detailed scheme of experimental measurements setup, are presented. The new design of accelerating structure of the IH-type such as POS-4, using the method of alternate-phase focusing with the step-by-step change of the synchronous phase along the focusing periods in a linear accelerator, is developed with the aim to irradiate the functional design materials by the Helium ions. The new design of the injector of the charged Helium ions with the energy of 120 KeV at the output of an accelerating tube and the accelerating structure of the type of POS-4 for the one time charged Helium ions acceleration in the linear accelerator are researched and developed. The special chamber for the irradiation of functional design materials by the Helium ions is also created. In the process of experiment, the temperature of a sample, the magnitude of current of Helium ions beam and the irradiation dose of sample are measured precisely. The experimental measurement setup and techniques are fully tested and optimized in the course of the research on the electro-physical properties of irradiated samples and the thermal-desorption of Helium ions in a wide range of temperatures

  15. Spectral studies on Ag 8+ ions irradiated LAHCl·H 2O and LAHBr·H 2O single crystals

    NASA Astrophysics Data System (ADS)

    Sangeetha, K.; Ramesh Babu, R.; Ramamurthi, K.; Prakash, Jai; Khan, S. A.

    2011-09-01

    L-Arginine hydrochloride monohydrate and L-arginine hydrobromide monohydrate single crystals are irradiated by 100 MeV Ag 8+ swift heavy ions. The residual gases liberated from the irradiated samples are monitored as a function of ion fluence using quadrupole mass analyzer. The C 2H 3+, C 2H 2, N 2, CO, HCl and CO 2 are the dominant gases liberated. Fourier transform infrared spectra of irradiated crystals explain the breaking of bonds in a localized region of the crystals. The crystallinity of irradiated crystals is analyzed by powder X-ray diffractions.

  16. Microarray Analysis of Human Liver Cells irradiated by 80MeV/u Carbon Ions

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Tian, Xiaoling; Kong, Fuquan; Li, Qiang; Jin, Xiaodong; Dai, Zhongying; Zhang, Hong; Yang, Mingjian; Zhao, Kui

    Objective Biological effect of heavy ion beam has the important significance for cancer therapy and space exploring owing its high LET and RBE, low OER, especially forming Bragg spike at the end of the tracks of charged particles. More serious damage for cells are induced by heavy ions and difficult repair than other irradiation such as X-ray and ?-ray . To explore the molecular mechanism of biological effect caused by heavy ionizing radiation (HIR) and to construct the gene expression profile database of HIR-induced human liver cells L02 by microarray analysis. Methods In this study, L02 cells were irradiated by 80MeV/u carbon ions at 5 Gy delivered by HIRFL (Heavy Ion Research Facility in Lanzhou) at room temperature. Total RNAs of cells incubated 6 hours and 24hours after irradiation were extracted with Trizol. Unirradiated cells were used as a control. RNAs were transcripted into cDNA by reverse transcription and labelled with cy5-dCTP and cy3-dCTP respectively. A human genome oligonucleotide set consisting of 5 amino acid-modified 70-mer probes and representing 21,329 well-characterized Homo sapiens genes was selected for microarray analysis and printed on amino-silaned glass slides. Arrays were fabricated using an OmniGrid microarrayer. Only genes whose alteration tendency was consistent in both microarrays were selected as differentially expressed genes. The Affymetrix's short oligonucleotide (25-mer) HG U133A 2.0 array analyses were performed per the manufacturer's instructions. Results Of the 21,329 genes tested, 37 genes showed changes in expression level with ratio higher than 2.0 and lower than 0.5 at 6hrs after irradiation. There were 19 genes showing up-regulation in radiated L02 cells, whereas 18 genes showing down-regulation; At 24hrs after irradiation, 269 genes showed changes in expression level with ratio higher than 2.0 and lower than 0.5. There were 67 genes showing up-regulation in radiated L02 cells, whereas 202 genes showing down-regulation. Furthermore 3 genes, ATP5G2, NFKBIE, RELB all showed up-regulation with ratio high than 2 at 6h and 24h after irradiation. Conclusion There are different gene expressions in L02 cells at 6h and 24h after irradiated by 5Gy carbon ions. The genes are mainly involved in DNA damage, cell cycle apoptosis, immune response and signal transduction in L02 cells. These results provide deeper insight into the mechanism of gene damage and repair after HIR.

  17. Modifications in optical and electrical properties of selenium nanowire arrays using ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Kumar, Narinder; Kumar, Rajesh; Kumar, Sushil; Chakarvarti, S. K.

    2015-11-01

    In the present paper, 80 MeV Si7+ ion beam-induced changes in selenium nanowire arrays, fabricated on copper substrates, have been examined. The nanowire arrays were electrodeposited into polymer membranes using template method. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-visible spectroscopy have been used to study the ion-induced effects in fabricated nanowire arrays. The XRD and FESEM results confirmed the formation of selenium nanowire arrays with trigonal structures. An intensity variation in the XRD peaks is observed for irradiated nanowires at different ion fluences. The band gap energy of the irradiated nanowire arrays was found to reduce compared with the pristine case. The irradiation of semiconducting selenium nanowires enhances the electrical conductivity. The current-voltage characterizations also confirm an enhancement in electrical conductivity of selenium nanowire arrays with an increase in ion fluence. This study is anticipated to greatly facilitate the design and development of nanodevices-based semiconductor nanowires which can be utilized even in the harsh environment.

  18. Tuning the hydrophobicity of mica surfaces by hyperthermal Ar ion irradiation

    SciTech Connect

    Keller, Adrian; Ogaki, Ryosuke; Bald, Ilko; Dong Mingdong; Kingshott, Peter; Fritzsche, Monika; Facsko, Stefan; Besenbacher, Flemming

    2011-03-14

    The hydrophobicity of surfaces has a strong influence on their interactions with biomolecules such as proteins. Therefore, for in vitro studies of bio-surface interactions model surfaces with tailored hydrophobicity are of utmost importance. Here, we present a method for tuning the hydrophobicity of atomically flat mica surfaces by hyperthermal Ar ion irradiation. Due to the sub-100 eV energies, only negligible roughening of the surface is observed at low ion fluences and also the chemical composition of the mica crystal remains almost undisturbed. However, the ion irradiation induces the preferential removal of the outermost layer of K{sup +} ions from the surface, leading to the exposure of the underlying aluminosilicate sheets which feature a large number of centers for C adsorption. The irradiated surface thus exhibits an enhanced chemical reactivity toward hydrocarbons, resulting in the adsorption of a thin hydrocarbon film from the environment. Aging these surfaces under ambient conditions leads to a continuous increase of their contact angle until a fully hydrophobic surface with a contact angle >80 deg. is obtained after a period of about 3 months. This method thus enables the fabrication of ultrasmooth biological model surfaces with precisely tailored hydrophobicity.

  19. Structures and field emission characteristics of ion irradiated silicon nanowire arrays.

    PubMed

    Zhao, Fei; Deng, Jian-hua; Zhao, Dan-dan; Chen, Ke-fan; Cheng, Guo-an; Zheng, Rui-ting

    2010-11-01

    Silicon nanowire (SiNW) arrays irradiated by energetic Si ions were fabricated by metal vapor vacuum arc (MEVVA) ion implantation method. Hetero-structure of amorphous/crystalline nanowire was formed in which structure of the implanted region on the top of the nanowires was amorphous while the structure of unimplanted region on the bottom remained crystal. Field emission (FE) properties of the SiNW arrays could be improved and modulated by different implantation doses. A low turn-on field of 4.63 V/microm was observed in the SiNWs irradiated by 21 keV Si ion with a dose of 7.86 x 10(16)/cm2, and the applied field for the emission current density reaching 100 microA/cm2 is only 5.52 V/microm. The main reason for the efficient emission is attributed to the formation of amorphous SiNWs and structure defects after implantation. The ion irradiated SiNWs after post-annealing at high temperature had better FE property due to eliminating the restrain effect to electrons. PMID:21137999

  20. Ag clustering investigation in laser irradiated ion-exchanged glasses by optical and vibrational spectroscopy

    NASA Astrophysics Data System (ADS)

    Trave, E.; Cattaruzza, E.; Gonella, F.; Calvelli, P.; Quaranta, A.; Rahman, A.; Mariotto, G.

    2012-09-01

    Ion exchange process is widely used to dope silicate glass layers with silver for several applications, ranging from light waveguide to nanostructured composite glass fabrication. The silver-doped structure and its physical properties depend on the preparation parameters as well as on subsequent treatments. In particular, laser irradiation of the ion exchanged glasses has been demonstrated to be an effective tool to control cluster size and size distribution. Nevertheless, a complete comprehension of the basic phenomena and a systematic characterization of these systems are still lacking. In this paper, an extended optical characterization is presented for soda-lime glass slides, doped with silver by Ag+-Na+ ion exchange, thermally treated and irradiated with a Nd:YAG laser beam at different wavelengths, and for different energy density. The samples were characterized by various spectroscopic techniques, namely, optical absorption, photoluminescence and micro-Raman analysis. The availability of all these characterization techniques allowed pointing out a suitable scenario for the Ag clustering evolution as a function of the ion exchange, annealing and laser irradiation parameters.

  1. Study on structural recovery of graphite irradiated with swift heavy ions at high temperature

    NASA Astrophysics Data System (ADS)

    Pellemoine, F.; Avilov, M.; Bender, M.; Ewing, R. C.; Fernandes, S.; Lang, M.; Li, W. X.; Mittig, W.; Schein, M.; Severin, D.; Tomut, M.; Trautmann, C.; Zhang, F. X.

    2015-12-01

    Thin graphite foils bombarded with an intense high-energy (8.6 MeV/u) gold beam reaching fluences up to 1 × 1015 ions/cm2 lead to swelling and electrical resistivity changes. As shown earlier, these effects are diminished with increasing irradiation temperature. The work reported here extends the investigation of beam induced changes of these samples by structural analysis using synchrotron X-ray diffraction and transmission electron microscope. A nearly complete recovery from swelling at irradiation temperatures above about 1500 °C is identified.

  2. Synthesis, characterization and effect of low energy Ar ion irradiation on gadolinium oxide nanoparticles

    SciTech Connect

    Paul, N.; Devi, M.; Mohanta, D.

    2011-08-15

    Graphical abstract: . The figure depicts Raman spectra of (A) unirradiated and (B) 80 keV Ar ion irradiated nanoscale gadolinium oxide (Gd{sub 2}O{sub 3}) systems. Intense Raman signals corresponding to two B{sub g} modes at 288 and 384 cm{sup -1} are observed for irradiated sample along with the evolution of a new peak at 202 cm{sup -1} due to surface defects. Highlights: {yields} Gadolinium oxide nanoparticles are synthesized via a selective reduction route. {yields} 80 keV Ar ion-irradiated specimen showed better symmetric emission than pristine. {yields} Irradiation led point defect contribution was studied through spectroscopic means. -- Abstract: In this work, we report on the surfactant assisted synthesis of gadolinium oxide (Gd{sub 2}O{sub 3}) nanoparticles and their characterization through various microscopic and spectroscopic tools. Exhibiting a monoclinic phase, the nanoscale Gd{sub 2}O{sub 3} particles are believed to be comprising of crystallites with an average size of {approx}3.2 nm, as revealed from the X-ray diffraction analysis. The transmission electron microscopy has predicted a particle size of {approx}9 nm and an interplanar spacing of {approx}0.28 nm. Fourier transform infrared spectroscopy studies show that Gd-O inplane vibrations at 536.8 and 413.3 cm{sup -1} were more prominent for 80-keV Ar-ion irradiated Gd{sub 2}O{sub 3} nanosystem than unirradiated system. The photoluminescence (PL) spectra of irradiated specimen have revealed an improvement in the symmetry factor owing to significant enhancement of surface-trap emission, compared to the band-edge counterpart. Irradiation induced creation of point defects (oxygen vacancies) were predicted both from PL and electron paramagnetic resonance (EPR) studies. Further, the Raman spectra of the irradiated sample have exhibited notable vibrational features along with the evolution of a new peak at {approx}202 cm{sup -1}. This can be ascribed to an additional Raman active vibrational response owing to considerable modification of the nanostructure surface as a result of ion bombardment. Probing nanoscale defects through prime spectroscopy tools would find a new avenue for precise tuning of physical properties with generation and annihilation of defects.

  3. Effect of chemical etching on poly(methyl methacrylate) irradiated with slow highly charged ions

    NASA Astrophysics Data System (ADS)

    Ritter, Robert; Wilhelm, Richard A.; Ginzel, Rainer; Schadauer, Philip; Heller, René; Rupp, Werner; Crespo López-Urrutia, José R.; Facsko, Stefan; Aumayr, Friedrich

    2013-09-01

    We have recently demonstrated that individual slow highly charged ions are able to produce nano-sized pits on poly(methyl methacrylate) surfaces as a result of direct ablation due to the deposition of their high potential energy, if this energy exceeds a critical minimum value. By exposing irradiated samples to a suitable etchant, such pits can be revealed even below this potential energy threshold as latent damage zones are removed. Existing pits grow both in diameter and in depth after contact with the etchant with different etching dynamics for both dimensions. Systematic studies on the response of irradiated samples to a chemical developer are presented.

  4. Evolution of surface morphology and electronic structure of few layer graphene after low energy Ar+ ion irradiation

    NASA Astrophysics Data System (ADS)

    Al-Harthi, S. H.; Kara'a, A.; Hysen, T.; Elzain, M.; Al-Hinai, A. T.; Myint, M. T. Z.

    2012-11-01

    We report on co-existing dual anisotropy ripple formation, sp bonding transformation, and variation in the delocalized ? electron system in 1 keV Ar+ ion irradiated few-layer graphene surfaces. Ripples in directions, perpendicular and parallel to the ion beam were found. The irradiation effect and the transition from the sp2-bonding to sp3-hybridized state were analyzed from the deconvolution of the C (1s) peak and from the shape of the derivative of the Auger transition spectra. The results suggest a plausible mechanism for tailoring of few-layer graphene electronic band structure with interlayer coupling tuned by the ion irradiation.

  5. Heavy-Ion Irradiation of Thulium(III) Oxide Targets Prepared by Polymer-Assisted Deposition

    SciTech Connect

    Garcia, Mitch A.; Ali, Mazhar N.; Chang, Noel N.; Parsons-Moss, Tashi; Ashby, Paul D.; Gates, Jacklyn M.; Stavsetra, Liv; Gregorich, Kenneth E.; Nitsche, Heino

    2008-09-15

    Thulium(III) oxide (Tm{sub 2}O{sub 3}) targets prepared by the polymer-assisted deposition (PAD) method were irradiated by heavy-ion beams to test the method's feasibility for nuclear science applications. Targets were prepared on silicon nitride backings (thickness of 1000 nm, 344 {micro}g/cm{sup 2}) and were irradiated with an {sup 40}Ar beam at laboratory frame energy of {approx}210 MeV (50 particle nA). The root mean squared (RMS) roughness prior to irradiation is 1.1 nm for a {approx}250 nm ({approx}220 {micro}g/cm{sup 2}) Tm{sub 2}O{sub 3} target, and an RMS roughness of 2.0 nm after irradiation was measured by atomic force microscopy (AFM). Scanning electron microscopy of the irradiated target reveals no significant differences in surface homogeneity when compared to imaging prior to irradiation. Target flaking was not observed from monitoring Rutherford scattered particles as a function of time.

  6. Irradiation With Carbon Ion Beams Induces Apoptosis, Autophagy, and Cellular Senescence in a Human Glioma-Derived Cell Line

    SciTech Connect

    Jinno-Oue, Atsushi; Shimizu, Nobuaki; Hamada, Nobuyuki; Wada, Seiichi; Tanaka, Atsushi; Shinagawa, Masahiko; Ohtsuki, Takahiro; Mori, Takahisa; Saha, Manujendra N.; Hoque, Ariful S.; Islam, Salequl; Kogure, Kimitaka; Funayama, Tomoo; Kobayashi, Yasuhiko

    2010-01-15

    Purpose: We examined biological responses of human glioma cells to irradiation with carbon ion beams (C-ions). Methods and Materials: A human glioma-derived cell line, NP-2, was irradiated with C-ions. Apoptotic cell nuclei were stained with Hoechst 33342. Induction of autophagy was examined either by staining cells with monodansylcadaverine (MDC) or by Western blotting to detect conversion of microtuble-associated protein light chain 3 (MAP-LC3) (LC3-I) to the membrane-bound form (LC3-II). Cellular senescence markers including induction of senescence-associated beta-galactosidase (SA-beta-gal) were examined. The mean telomere length of irradiated cells was determined by Southern blot hybridization. Expression of tumor suppressor p53 and cyclin/cyclin-dependent kinase inhibitor p21{sup WAF1/CIP1} in the irradiated cells was analyzed by Western blotting. Results: When NP-2 cells were irradiated with C-ions at 6 Gy, the major population of the cells died of apoptosis and autophagy. The residual fraction of attached cells (<1% of initially irradiated cells) could not form a colony: however, they showed a morphological phenotype consistent with cellular senescence, that is, enlarged and flattened appearance. The senescent nature of these attached cells was further indicated by staining for SA-beta-gal. The mean telomere length was not changed after irradiation with C-ions. Phosphorylation of p53 at serine 15 as well as the expression of p21{sup WAF1/CIP1} was induced in NP-2 cells after irradiation. Furthermore, we found that irradiation with C-ions induced cellular senescence in a human glioma cell line lacking functional p53. Conclusions: Irradiation with C-ions induced apoptosis, autophagy, and cellular senescence in human glioma cells.

  7. Virus inactivation studies using ion beams, electron and gamma irradiation

    NASA Astrophysics Data System (ADS)

    Smolko, Eduardo E.; Lombardo, Jorge H.

    2005-07-01

    Known methods of virus inactivation are based on the chemical action of some substances such as acetylethylenimine, betapropiolactone, glycidalaldehyde, formaldehyde, etc. In such a process, the viral suspension should be kept at room or higher temperatures for 24-48 h. Under these conditions, physical and chemical agents act to degrade the virus antigenic proteins. On the contrary with ionizing radiations at low temperatures, the treatment does not cause such degradation allowing the study of different viral functions. In this work, particle (?, d and ß) and ? irradiations were used for partial and total inactivation of Foot and Mouth Disease Virus (FMDV), Rauscher Leukemia Virus (RLV) and Herpes Simplex Virus (HSV). Obtention of the D37 dose from survival curves and the application of the target theory, permitted the determination of molecular weight of the nucleic acid genomes, EBR values and useful information for vaccine preparation. For RLV virus, a two target model of the RNA genome was deduced in accordance with biological information while from data from the literature and our own work on the structure of the scrapie prion, considering the molecular weight obtained by application of the theory, a new model for prion replication is presented, based on a trimer molecule.

  8. Formation of dislocations and hardening of LiF crystals irradiated with energetic Au, Bi, Pb, and S ions

    NASA Astrophysics Data System (ADS)

    Maniks, J.; Manika, Ilze; Schwartz, K.; Toulemonde, M.; Trautmann, C.

    2003-08-01

    The irradiation of LiF crystals with Au, Pb, Bi, and S ions in the range of 400 - 2200 MeV leads to a remarkable increase of the hardness. The effect appears for Bi and Pb ions at fluences above 109 ions/cm2 and for S ions above 1010 ions/cm2. The increase of hardness follows the energy loss and is related to the formation of defects along the ion path. Defect complexes, clusters and aggregates with nanoscale dimensions serve as strong obstacles for dislocations and cause dispersion strengthening. Structural investigations reveal the generation of long-range stress in the adjacent non-irradiated part of the crystal. Close to the implantation zone, the stress exceeds the yield strength, causing microplastic deformation and work hardening. Compared to light S ions, heavy ions (Au, Pb, Bi) cause more severe structural damage, larger hardening effects, and higher internal and long-range stress.

  9. In situ observation of defect annihilation in Kr ion-irradiated bulk Fe/amorphous-Fe 2 Zr nanocomposite alloy

    DOE PAGESBeta

    Yu, K. Y.; Fan, Z.; Chen, Y.; Song, M.; Liu, Y.; Wang, H.; Kirk, M. A.; Li, M.; Zhang, X.

    2014-08-26

    Enhanced irradiation tolerance in crystalline multilayers has received significant attention lately. However, little is known on the irradiation response of crystal/amorphous nanolayers. We report on in situ Kr ion irradiation studies of a bulk Fe96Zr4 nanocomposite alloy. Irradiation resulted in amorphization of Fe2Zr and formed crystal/amorphous nanolayers. ?-Fe layers exhibited drastically lower defect density and size than those in large ?-Fe grains. In situ video revealed that mobile dislocation loops in ?-Fe layers were confined by the crystal/amorphous interfaces and kept migrating to annihilate other defects. This study provides new insights on the design of irradiation-tolerant crystal/amorphous nanocomposites.

  10. Upper critical field and Raman spectra of MgB2 thin films irradiated with low energy oxygen ion

    NASA Astrophysics Data System (ADS)

    Wang, J.; Zhuang, C. G.; Li, J.; Wang, Y. Z.; Feng, Q. R.; Zheng, D. N.

    2009-11-01

    The structure, upper critical field, and Raman spectrum of epitaxial MgB2 thin films irradiated by 300 keV O2+ ions have been investigated. Lattice parameter c expands after irradiation. There is a significant increase in upper critical field in the moderately irradiated films, while the critical temperature is reduced slightly. The values of critical field at zero temperature exhibit a maximum for samples with a moderate irradiation level for the applied magnetic field both perpendicular and parallel to the film surface. The temperature dependence of the anisotropy parameter, which is defined as the ratio of the upper critical field with the field parallel to the film surface and perpendicular to the film surface, reveals that oxygen ion irradiation mainly affects the ? band at a low irradiation level. With increasing irradiation level, ? band scattering is strongly enhanced, and finally both bands are in the dirty limit. A broad peak centered around 570 cm-1 is observed in the Raman spectrum of the unirradiated films, and the peak position has a visible redshift in the irradiated samples. In particular, high-frequency spectral structures appear and become dominant, while the E2g broad band diminishes gradually with increasing irradiation fluence. The results are discussed by considering the disorder-induced change in carrier scattering within and between the ? and ? bands and a violation of the Raman selection rules due to oxygen ion irradiation.

  11. Wide variety of flower-color and -shape mutants regenerated from leaf cultures irradiated with ion beams

    NASA Astrophysics Data System (ADS)

    Okamura, M.; Yasuno, N.; Ohtsuka, M.; Tanaka, A.; Shikazono, N.; Hase, Y.

    2003-05-01

    The efficiency of ion-beam irradiation combined with tissue culture in obtaining floral mutants was investigated and compared with those of gamma rays and X-rays in carnation. Leaf segments of carnation plants in vitro were irradiated with the 220 MeV carbon ions, and cultured till the shoot regenerated. The carbon ion had the highest effect in reducing the regeneration frequency, and the RBE value with respect to gamma-rays was four. The higher mutation frequency and the wider mutation spectrum were obtained in plants irradiated with the carbon ions than low LET radiations. Three new carnation varieties developed by ion-beam irradiation were applied for the registration of the Japanese Ministry of Agriculture, Forestry and Fisheries. The results indicate that ion beam irradiation could induce wide variety of flower-color and -shape mutants, and that the combined method of ion-beam irradiation with tissue culture is useful to obtain the commercial varieties in a short time.

  12. Phase transformations in Ln2O3 materials irradiated with swift heavy ions

    NASA Astrophysics Data System (ADS)

    Tracy, Cameron L.; Lang, Maik; Zhang, Fuxiang; Trautmann, Christina; Ewing, Rodney C.

    2015-11-01

    Phase transformations induced in the cubic C-type lanthanide sesquioxides, Ln2O3 (Ln = Sm, Gd, Ho, Tm, and Lu), by dense electronic excitation are investigated. The structural modifications resulting from exposure to beams of 185 MeV Xe and 2246 MeV Au ions are characterized using synchrotron x-ray diffraction and Raman spectroscopy. The formation of a B-type polymorph, an X-type nonequilibrium phase, and an amorphous phase are observed. The specific phase formed and the transformation rate show dependence on the material composition, as well as the ion beam mass and energy. Atomistic mechanisms for these transformations are determined, indicating that formation of the B-type phase results from the production of anti-Frenkel defects and the aggregation of anion vacancies into planar clusters, whereas formation of the X-type and amorphous phases requires extensive displacement of both anions and cations. The observed variations in phase behavior with changing lanthanide ionic radius and deposited electronic energy density are related to the energetics of these transformation mechanisms.

  13. Stress-induced patterns in ion-irradiated Silicon: a model based on anisotropic plastic flow

    E-print Network

    Scott A. Norris

    2012-07-24

    We present a model for the effect of stress on thin amorphous films that develop atop ion-irradiated silicon, based on the mechanism of ion-induced anisotropic plastic flow. Using only parameters directly measured or known to high accuracy, the model exhibits remarkably good agreement with the wavelengths of experimentally-observed patterns, and agrees qualitatively with limited data on ripple propagation speed. The predictions of the model are discussed in the context of other mechanisms recently theorized to explain the wavelengths, including extensive comparison with an alternate model of stress.

  14. Temporal stability of Y Ba Cu O nano Josephson junctions from ion irradiation

    SciTech Connect

    Cybart, Shane A.; Roediger, Peter; Chen, Ke; Parker, J. M.; Cho, Ethan Y.; Wong, Travis J.; Dynes, R. C.

    2012-11-29

    We investigate the temporal stability of YBa2Cu3O7 Josephson junctions created by ion irradiation through a nano-scale implant mask fabricated using electron beam lithography and reactive ion etching. A comparison of current-voltage characteristics measured for junctions after fabrication and eight years of storage at room temperature show a slight decrease in critical current and increase in normal state resistance consistent with broadening of the weaklink from diffusion of defects. Shapiro step measurements performed 8 years after fabrication reveal that device uniformity is maintained and is strong evidence that these devices have excellent temporal stability for applications.

  15. Laser irradiations of advanced targets promoting absorption resonance for ion acceleration in TNSA regime

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Calcagno, L.; Giulietti, D.; Cutroneo, M.; Zimbone, M.; Skala, J.

    2015-07-01

    Advanced targets based on Au nanoparticles embedded in polymers films show high absorption coefficient in the UV-visible and infrared region. They can be employed to enhance the proton and ion acceleration from the laser-generated plasma in TNSA regime. In conditions of "p" polarized laser irradiations at 1015 W/cm2 intensity, in these films can be induced resonant absorption due to plasma wave excitation. Plasma on-line diagnostics is based on SiC detectors, Thomson spectrometry and X-ray streak camera imaging. Measurements of kinetic energy of accelerated ions indicate a significant increment using polymer targets containing gold nanoparticles and "p" polarized laser light with respect to pure polymers and unpolarized light irradiation.

  16. Optical waveguides in LiTaO3 crystals fabricated by swift C5+ ion irradiation

    NASA Astrophysics Data System (ADS)

    Liu, Guiyuan; He, Ruiyun; Akhmadaliev, Shavkat; Vázquez de Aldana, Javier R.; Zhou, Shengqiang; Chen, Feng

    2014-04-01

    We report on the optical waveguides, in both planar and ridge configurations, fabricated in LiTaO3 crystal by using carbon (C5+) ions irradiation at energy of 15 MeV. The planar waveguide was produced by direct irradiation of swift C5+ ions, whilst the ridge waveguides were manufactured by using femtosecond laser ablation of the planar layer. The reconstructed refractive index profile of the planar waveguide has showed a barrier-shaped distribution, and the near-field waveguide mode intensity distribution was in good agreement with the calculated modal profile. After thermal annealing at 260 °C in air, the propagation losses of both the planar and ridge waveguides were reduced to 10 dB/cm.

  17. Outgassing and degradation of polyimide induced by swift heavy ion irradiation at cryogenic temperature

    SciTech Connect

    Severin, D.; Balanzat, E.; Ensinger, W.; Trautmann, C.

    2010-07-15

    Polyimide foils were irradiated with energetic Kr (740 MeV) and Pb (890 MeV) ions at cryogenic temperature (12 K). Beam-induced degradation processes were monitored by residual gas analysis and online infrared spectroscopy. The outgassing components observed at low irradiation temperatures differ in quantity but are similar in mass distribution to those identified at room temperature exposure. Besides CO as major volatile fragment, a significant contribution of short hydrocarbons like C{sub 2}H{sub x} is released. In situ infrared spectroscopy indicates accumulation of CO and CO{sub 2} molecules at 12 K in the foils. During heat-up cycles, most of these frozen gases become mobile and outgas at a temperature between 35 and 55 K. The study is motivated by the application of polyimide foils as insulating material in high radiation environment of the future accelerator facility for antiproton and ion research (FAIR).

  18. Evolution of nanoripples on silicon by gas cluster-ion irradiation

    SciTech Connect

    Lozano, Omar; Chen, Q. Y.; Wadekar, P. V.; Chinta, P. V.; Tilakaratne, B. P.; Wang, X. M.; Wijesundera, D.; Chu, W. K.; Seo, H. W.; Tu, L. W.; Ho, N. J.

    2013-06-15

    Si wafers of (100), (110) and (111) orientations were bombarded by gas cluster ion beam (GCIB) of 3000 Ar-atoms/cluster on average at a series of angles. Similar surface morphology ripples developed in different nanoscales. A simple scaling functional satisfactorily describe the roughness and wavelength of the ripple patterns as a function of dosage and angle of incidence. The ripples are formed orthogonal to the incident cluster-ions at large off-normal angles. An ellipsoidal pattern was created by two consecutive irradiations incident in mutually orthogonal directions with unequal exposure times between each irradiation, from 7:1 to 10:1, beyond which the original ripple imprints would be over-written. This work was inspired by use of the ripples to seed growth of controlled nanostructures without patterning by lithography or predeposition of catalysts.

  19. Temperature-Ramped 129Xe Spin-Exchange Optical Pumping

    PubMed Central

    2015-01-01

    We describe temperature-ramped spin-exchange optical pumping (TR-SEOP) in an automated high-throughput batch-mode 129Xe hyperpolarizer utilizing three key temperature regimes: (i) “hot”—where the 129Xe hyperpolarization rate is maximal, (ii) “warm”—where the 129Xe hyperpolarization approaches unity, and (iii) “cool”—where hyperpolarized 129Xe gas is transferred into a Tedlar bag with low Rb content (<5 ng per ?1 L dose) suitable for human imaging applications. Unlike with the conventional approach of batch-mode SEOP, here all three temperature regimes may be operated under continuous high-power (170 W) laser irradiation, and hyperpolarized 129Xe gas is delivered without the need for a cryocollection step. The variable-temperature approach increased the SEOP rate by more than 2-fold compared to the constant-temperature polarization rate (e.g., giving effective values for the exponential buildup constant ?SEOP of 62.5 ± 3.7 × 10–3 min–1 vs 29.9 ± 1.2 × 10–3 min–1) while achieving nearly the same maximum %PXe value (88.0 ± 0.8% vs 90.1% ± 0.8%, for a 500 Torr (67 kPa) Xe cell loading—corresponding to nuclear magnetic resonance/magnetic resonance imaging (NMR/MRI) enhancements of ?3.1 × 105 and ?2.32 × 108 at the relevant fields for clinical imaging and HP 129Xe production of 3 T and 4 mT, respectively); moreover, the intercycle “dead” time was also significantly decreased. The higher-throughput TR-SEOP approach can be implemented without sacrificing the level of 129Xe hyperpolarization or the experimental stability for automation—making this approach beneficial for improving the overall 129Xe production rate in clinical settings. PMID:25008290

  20. Temperature-ramped (129)Xe spin-exchange optical pumping.

    PubMed

    Nikolaou, Panayiotis; Coffey, Aaron M; Barlow, Michael J; Rosen, Matthew S; Goodson, Boyd M; Chekmenev, Eduard Y

    2014-08-19

    We describe temperature-ramped spin-exchange optical pumping (TR-SEOP) in an automated high-throughput batch-mode (129)Xe hyperpolarizer utilizing three key temperature regimes: (i) "hot"-where the (129)Xe hyperpolarization rate is maximal, (ii) "warm"-where the (129)Xe hyperpolarization approaches unity, and (iii) "cool"-where hyperpolarized (129)Xe gas is transferred into a Tedlar bag with low Rb content (<5 ng per ?1 L dose) suitable for human imaging applications. Unlike with the conventional approach of batch-mode SEOP, here all three temperature regimes may be operated under continuous high-power (170 W) laser irradiation, and hyperpolarized (129)Xe gas is delivered without the need for a cryocollection step. The variable-temperature approach increased the SEOP rate by more than 2-fold compared to the constant-temperature polarization rate (e.g., giving effective values for the exponential buildup constant ?SEOP of 62.5 ± 3.7 × 10(-3) min(-1) vs 29.9 ± 1.2 × 10(-3) min(-1)) while achieving nearly the same maximum %PXe value (88.0 ± 0.8% vs 90.1% ± 0.8%, for a 500 Torr (67 kPa) Xe cell loading-corresponding to nuclear magnetic resonance/magnetic resonance imaging (NMR/MRI) enhancements of ?3.1 × 10(5) and ?2.32 × 10(8) at the relevant fields for clinical imaging and HP (129)Xe production of 3 T and 4 mT, respectively); moreover, the intercycle "dead" time was also significantly decreased. The higher-throughput TR-SEOP approach can be implemented without sacrificing the level of (129)Xe hyperpolarization or the experimental stability for automation-making this approach beneficial for improving the overall (129)Xe production rate in clinical settings. PMID:25008290

  1. Electron capture from H-2 to highly charged Th and Xe ions trapped at center-of-mass energies near 6 eV 

    E-print Network

    Weinberg, G.; Beck, B. R.; Steiger, J.; Church, David A.; McDonald, J.; Schneider, D.

    1998-01-01

    by ramping the axial oscillation frequencies of the ions through resonance with a tuned circuit composed in part of trap capacitance and an external inductor. This produced resonance signals whose square is proportional to the number of ions in each charge...

  2. Dielectric Studies on Swift Heavy Ions and Electron Irradiated Organic Single Crystal

    SciTech Connect

    Crasta, Vincent; Kumar, P. C. Rajesh; Ravindrachary, V.; Ganesh, S.

    2011-07-15

    Single crystals of 1-(4-methylphenyl)-3-(4,N,N-dimethylamino phenyl)-2-propen-1-one were irradiated with 72 MeV swift heavy ions of C-12 with different fluencies 5x10{sup 11}, 1x10{sup 12} and electrons with energy 8 MeV for a dose of 2.25 kGy. The changes in the dielectric properties of these crystals have been studied. The study shows that the dielectric constant increases first and then decreases with the increase of fluence. This variation has been discussed and possible explanations are given. The variation of dielectric loss and the ac conductivity indicates that there is some structural modification within the crystal due to irradiation. The electron irradiation induced ionic polarizibility within the crystal along the electron path, which is reflected in increase in dielectric constant and hence the conductivity.

  3. Ion irradiation of Allende meteorite probed by visible, IR, and Raman spectroscopies

    NASA Astrophysics Data System (ADS)

    Brunetto, R.; Lantz, C.; Ledu, D.; Baklouti, D.; Barucci, M. A.; Beck, P.; Delauche, L.; Dionnet, Z.; Dumas, P.; Duprat, J.; Engrand, C.; Jamme, F.; Oudayer, P.; Quirico, E.; Sandt, C.; Dartois, E.

    2014-07-01

    Little is known about carbonaceous asteroids weathering in space as previous studies have struggled to define a general spectral trend among dark surfaces. Here we present experiments on ion irradiation of the Allende meteorite, performed using 40 keV He+ and Ar+ ions, as a simulation of solar wind irradiation of primitive bodies surfaces. We used different fluences up to 3 × 1016 ions/cm2, corresponding to short timescales of ?103-104 yrs in the main asteroid belt. Samples were analyzed before and after irradiation using visible to far-IR (0.4-50 ?m) reflectance spectroscopy, and Raman micro-spectroscopy. Similarly to what observed in previous experiments, results show a reddening and darkening of VIS-NIR reflectance spectra. These spectral variations are however comparable to other spectral variations due to viewing geometry, grain size, and sample preparation, suggesting an explanation for the contradictory space weathering studies of dark asteroids. After irradiation, the infrared bands of the matrix olivine silicates change profile and shift to longer wavelength, possibly as a consequence of a more efficient sputtering effect on Mg than Fe (lighter and more volatile species are preferentially sputtered backwards) and/or preferential amorphization of Mg-rich olivine. Spectral variations are compatible with the Hapke weathering model. Raman spectroscopy shows that the carbonaceous component is substantially affected by irradiation: different degrees of de-ordering are produced as a function of dose, to finally end with a highly disordered carbon. All observed modifications seem to scale with the nuclear elastic dose.

  4. Ion irradiation: its relevance to the evolution of complex organics in the outer solar system.

    PubMed

    Strazzulla, G

    1997-01-01

    Ion irradiation of carbon containing ices produces several effects among which the formation of complex molecules and even refractory organic materials whose spectral color and molecular complexity both depend on the amount of deposited energy. Here results from laboratory experiments are summarized. Their relevance for the formation and evolution of simple molecules and complex organic materials on planetary bodies in the external Solar System is outlined. PMID:11541336

  5. Continuous wave waveguide lasers of swift argon ion irradiated Nd:YVO4 waveguides.

    PubMed

    Yao, Yicun; Dong, Ningning; Chen, Feng; Pang, Lilong; Wang, Zhiguang; Lu, Qingming

    2011-11-21

    We report on the fabrication of planar waveguide in Nd:YVO(4) crystal by using swift Ar(8+) ion irradiation. At room temperature continuous wave (cw) laser oscillation at wavelength of ~1067 nm has been realized through the optical pump at 808 nm with a low threshold of 9.3 mW. The slope efficiency of the waveguide laser system is of 8.5%. The optical-to-optical conversion efficiency is 6.6%. PMID:22109451

  6. Second harmonic generation of swift carbon ion irradiated Nd:GdCOB waveguides.

    PubMed

    Ren, Yingying; Jia, Yuechen; Chen, Feng; Lu, Qingming; Akhmadaliev, Sh; Zhou, Shengqiang

    2011-06-20

    We report on the second harmonic generation at ~532 nm of optical waveguides in Nd:GdCOB produced by swift carbon ion irradiation. The fabricated waveguide shows good guiding property. Under pump of ~1064-nm fundamental light, the optical conversion efficiency of the frequency doubling is 0.48% W(-1) and 6.8% W(-1) for continuous wave and pulsed laser beams, respectively. PMID:21716488

  7. Heavy ion irradiation of crystalline water ice. Cosmic ray amorphisation cross-section and sputtering yield

    NASA Astrophysics Data System (ADS)

    Dartois, E.; Augé, B.; Boduch, P.; Brunetto, R.; Chabot, M.; Domaracka, A.; Ding, J. J.; Kamalou, O.; Lv, X. Y.; Rothard, H.; da Silveira, E. F.; Thomas, J. C.

    2015-04-01

    Context. Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. Aims: We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. Methods: We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). Results: The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic stopping power. Conclusions: The final state of cosmic ray irradiation for porous amorphous and crystalline ice, as monitored by infrared spectroscopy, is the same, but with a large difference in cross-section, hence in time scale in an astrophysical context. The cosmic ray water-ice sputtering rates compete with the UV photodesorption yields reported in the literature. The prevalence of direct cosmic ray sputtering over cosmic-ray induced photons photodesorption may be particularly true for ices strongly bonded to the ice mantles surfaces, such as hydrogen-bonded ice structures or more generally the so-called polar ices. Experiments performed at the Grand Accélérateur National d'Ions Lourds (GANIL) Caen, France. Part of this work has been financed by the French INSU-CNRS programme "Physique et Chimie du Milieu Interstellaire" (PCMI) and the ANR IGLIAS.

  8. The study of optical property of sapphire irradiated with 73 MeV Ca ions

    NASA Astrophysics Data System (ADS)

    Yang, Yitao; Zhang, Chonghong; Song, Yin; Gou, Jie; Liu, Juan; Xian, Yongqiang

    2015-12-01

    Single crystals of sapphire were irradiated with 73 MeV Ca ions at room temperature to the fluences of 0.1, 0.5 and 1.0 × 1014 ions/cm2. Optical properties of these samples were characterized by ultraviolet-visible spectrometry (UV-VIS) and fluorescence spectrometer (PL). In UV-VIS spectra, it is observed the absorbance bands from oxygen single vacancy (F and F+ color centers) and vacancy pair (F2+ and F22+ color centers). The oxygen single vacancy initially increases rapidly and then does not increase in the fluence range from 0.1 to 0.5 × 1014 ions/cm2. When the fluence is higher than 0.5 × 1014 ions/cm2, oxygen single vacancy starts to increase again. Oxygen vacancy pair increases monotonically with fluence for all irradiated samples. The variation of oxygen single vacancy with fluence is probably associated with the recombination of oxygen vacancies with Al interstitials and complex defect formation (such as vacancy clusters). From PL spectra, two emission bands around 3.1 and 2.34 eV are observed. The PL intensity of the emission band around 3.1 eV decreases for all the irradiated samples. For the emission band around 2.34 eV, the PL intensity initially decreases, and then increases with fluence. Meanwhile, the peak position of the emission band around 2.34 eV gradually shifts to high energy direction with increase of fluence. The decrease of the intensity of the emission bands around 3.1 and 2.34 eV could be induced by stress from the damage layer in the irradiated samples. The shift of peak position for the emission band around 2.34 eV is induced by the appearance of emission band from Al interstitials.

  9. Synthesis of HCN and HNC in Ion-Irradiated N2-Rich Ices

    NASA Technical Reports Server (NTRS)

    Moore, M. H.; Hudson, R. L.; Ferrante, R. F.

    2002-01-01

    Near-IR observations reveal that N2-rich ice containing small amounts of CH4, and CO, is abundant on the surfaces of Triton, a moon of Neptune, and Pluto. N2-rich ices may also exist, in interstellar environments. To investigate the radiation chemistry of such ices we performed a systematic IR study of ion-irradiated Nz-rich mixtures containing CH4 and CO. Irradiation of N2 + CH4 mixtures at 12 K, showed that HCN, HNC, diazomethane, and NH3 were produced. We also found that UV photolysis of these ices produced detectable HCN and HNC. Intrinsic band strengths, A(HCN) and A(HNC), were measured and used to calculate yields of HCN and HNC. Similar results were obtained on irradiation of N2 + CH4 + CO ices at 12 K, with the main difference being the formation of HNCO. In all cases we observed changes on warming. For example, when the temperature of irradiated Nz + CH4 + CO was raised from 12 to 30 K, HCN, HNC, and HNCO reacted with NH3, and OCN-, CN-, N3-, and NH4+ were produced. These ions, appearing at 30 K, are expected to form and survive on the surfaces of Triton, Pluto, and interstellar grains. Our results have astrobiological implications since some of these radiation products are involved in the syntheses of biomolecules such as amino acids and peptides.

  10. Deuterium trapping at defects created with neutron and ion irradiations in tungsten

    SciTech Connect

    Y. Hatano; M. Shimada; T. Otsuka; Y. Oya; V.Kh. Alimov; M. Hara; J. Shi; M. Kobayashi; T. Oda; G. Cao; K. Okuno; T. Tanaka; K. Sugiyama; J. Roth; B. Tyburska-Püschel; J. Dorner; N. Yoshida; N. Futagami; H. Watanabe; M. Hatakeyama; H. Kurishita; M. Sokolov; Y. Katoh

    2013-07-01

    The effects of neutron and ion irradiations on deuterium (D) retention in tungsten (W) were investigated. Specimens of pure W were irradiated with neutrons to 0.3 dpa at around 323 K and then exposed to high-flux D plasma at 473 and 773 K. The concentration of D significantly increased by neutron irradiation and reached 0.8 at% at 473 K and 0.4 at% at 773 K. Annealing tests for the specimens irradiated with 20 MeV W ions showed that the defects which play a dominant role in the trapping at high temperature were stable at least up to 973 K, while the density decreased at temperatures equal to or above 1123 K. These observations of the thermal stability of traps and the activation energy for D detrapping examined in a previous study (˜1.8 eV) indicated that the defects which contribute predominantly to trapping at 773 K were small voids. The higher concentration of trapped D at 473 K was explained by additional contributions of weaker traps. The release of trapped D was clearly enhanced by the exposure to atomic hydrogen at 473 K, though higher temperatures are more effective for using this effect for tritium removal in fusion reactors.

  11. Modifications of yttria fully stabilized zirconia thin films by ion irradiation in the inelastic collision regime

    SciTech Connect

    Caricato, A. P.; Lamperti, A.; Ossi, P. M.; Trautmann, C.; Vanzetti, L.

    2008-11-01

    Yttria fully stabilized zirconia (FSZ) is a candidate material for nuclear inert matrix fuel cell and nuclear waste containment due to its isostructure with UO{sub 2} and PuO{sub 2} and its outstanding radiation resistance. Amorphous and polycrystalline cubic FSZ thin films of thickness around 400 nm were deposited on (100) Si by ultraviolet pulsed laser ablation and irradiated with 2.6 GeV uranium ions at fluences between 2x10{sup 11} and 1.2x10{sup 12} ions cm{sup -2}. The films were characterized before and after irradiation using scanning electron microscopy, atomic force microscopy, grazing incidence x-ray diffraction, and x-ray photoelectron spectroscopy (XPS). Amorphization, followed by partial recrystallization, is observed for irradiated crystalline films, whereas the amorphous films remain unaltered. A shift in the relative position of the XPS Zr 3d, Y 3d, and O 1s core lines is observed upon irradiation both in the crystalline and amorphous films, indicating differences in the local chemical environment at the surface as well as in near-surface layers. Such changes are ascribed to oxygen migration at the film surface, which may promote the recrystallization of as-deposited crystalline films but does not affect amorphous films.

  12. Ion irradiation induced nanocrystal formation in amorphous Zr 55Cu 30Al 10Ni 5 alloy

    NASA Astrophysics Data System (ADS)

    Carter, Jesse; Fu, E. G.; Martin, Michael; Xie, Guoqiang; Zhang, X.; Wang, Y. Q.; Wijesundera, D.; Wang, X. M.; Chu, Wei-Kan; McDeavitt, Sean M.; Shao, Lin

    2009-09-01

    Ion irradiation can be used to induce partial crystallization in metallic glasses to improve their surface properties. We investigated the microstructural changes in ribbon Zr 55Cu 30Al 10Ni 5 metallic glass after 1 MeV Cu-ion irradiation at room temperature, to a fluence of 1.0 × 10 16 cm -2. In contrast to a recent report by others that there was no irradiation induced crystallization in the same alloy [S. Nagata, S. Higashi, B. Tsuchiya, K. Toh, T. Shikama, K. Takahiro, K. Ozaki, K. Kawatusra, S. Yamamoto, A. Inouye, Nucl. Instr. and Meth. B 257 (2007) 420], we have observed nanocrystals in the as-irradiated samples. Two groups of nanocrystals, one with diameters of 5-10 nm and another with diameters of 50-100 nm are observed by using high resolution transmission electron microscopy. Experimentally measured planar spacings ( d-values) agree with the expectations for Cu 10Zr 7, NiZr 2 and CuZr 2 phases. We further discussed the possibility to form a substitutional intermetallic (Ni xCu 1-x)Zr 2 phase.

  13. Low energy singly and multiply charged ion irradiation of astrophysical ices

    NASA Astrophysics Data System (ADS)

    Dawes, A.; Holtom, P. D.; Mukerji, R. J.; Davis, M. P.; Sivaraman, B.; McCullough, R. W.; Williams, I.; Mason, N. J.

    Ion induced processes play an important role in the chemical modification of astrophysical ices, both on the surfaces of satellites in the outer solar system and in the depths of dark molecular clouds where few photons penetrate. To date many laboratory studies have been developed to study energetic singly charged ion interactions with astrophysical ice analogues (e.g. Mennella, et al 2004; Strazzulla, Baratta & Palumbo 2001; Gerakines, Moore, & Hudson 2000) and have been found to produce new chemical species and cause significant effects on ice morphology (Palumbo 2005). However, the effects of low energy and multiply charged ions have not yet been investigated. Such ions are prevalent in many astrophysical environments: as primary and secondary particles generated by cosmic ray bombardment and as constituents of planetary magnetospheres (e.g. Jupiter and Saturn). These ions comprise a rich variety of reactive species in a variety of charge states with typical kinetic energies of few keV. The effect of slow, multiply charged ions (MCIs) with the surfaces of astrophysical ices and their possible effect on chemical processing is unclear. However, studies of MCI impacts with insulator surfaces suggest that they may play an important role due to surplus potential energy imparted at the surface of the target (Winter & Aumayr 2001). We have developed a research program to study ion interactions with astrophysical ices using an Electron Cyclotron Resonance (ECR) ion source at Queens University Belfast. Such a source can produce different species of ions with variable energy and different charge states. Ices are prepared in situ by depositing gas onto a cold infrared transmitting window. Samples are analysed using FTIR spectroscopy during irradiation. We have conducted a series of experiments to investigate the effects of ion charge state (potential vs. kinetic energy effects), ion energy (nuclear vs. electronic stopping processes) and sample temperature. In this poster we present the results of irradiation of low and high temperature H2O ice films with Cn+ (n = 1, 2, 4) ions at 2 - 4 keV. The significance of the results will be discussed and possible reaction pathways for the formation of new products (CO and CO2) proposed.

  14. Role of impact parameter in branching reactions: Chemical accelerator studies of the reaction Xe++CH4?XeCH3 ++H

    E-print Network

    Miller, G. D.; Strattan, L. W.; Hierl, Peter M.

    1981-01-01

    Integral reaction cross sections and product velocity distributions have been measured for the ion–molecule reaction Xe+(CH4,H)XeCH3 + over the relative reactant translational energy range of 0.7–5.5 eV by chemical accelerator ...

  15. Induction of somatic instability in stable yellow leaf mutant of rice by ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Maekawa, M.; Hase, Y.; Shikazono, N.; Tanaka, A.

    2003-05-01

    Any class II type active transposons have not been discovered in rice though transposon (mobile element) is very useful for gene isolation in several plant species. In order to capture somatic instability induced by an endogenous active transposon in rice, stable yellow leaf plants derived from a variegated yellow leaf ( yl-v) mutant found in F2 of a cross between distantly related rice varieties were irradiated with carbon and helium ion beams. In M1 plants derived from the seeds irradiated with 50 Gy of 220 MeV carbon ions, a variegated yl plant was generated and this plant showed small or large sectors in leaves expanded later. Most of panicle-row M2 lines segregated into variegated and stable yl plants. In total, the ratio of variegated to stable yl plants was 3:1, suggesting that clear variegation observed on M1 plants might be caused by activation of a cryptic inactive autonomous element by carbon ion beam irradiation.

  16. Cellular and molecular portrait of eleven human glioblastoma cell lines under photon and carbon ion irradiation.

    PubMed

    Ferrandon, S; Magné, N; Battiston-Montagne, P; Hau-Desbat, N-H; Diaz, O; Beuve, M; Constanzo, J; Chargari, C; Poncet, D; Chautard, E; Ardail, D; Alphonse, G; Rodriguez-Lafrasse, C

    2015-04-28

    This study aimed to examine the cellular and molecular long-term responses of glioblastomas to radiotherapy and hadrontherapy in order to better understand the biological effects of carbon beams in cancer treatment. Eleven human glioblastoma cell lines, displaying gradual radiosensitivity, were irradiated with photons or carbon ions. Independently of p53 or O(6)-methylguanine-DNA methyltransferase(1) status, all cell lines responded to irradiation by a G2/M phase arrest followed by the appearance of mitotic catastrophe, which was concluded by a ceramide-dependent-apoptotic cell death. Statistical analysis demonstrated that: (i) the SF2(2) and the D10(3) values for photon are correlated with that obtained in response to carbon ions; (ii) regardless of the p53, MGMT status, and radiosensitivity, the release of ceramide is associated with the induction of late apoptosis; and (iii) the appearance of polyploid cells after photon irradiation could predict the Relative Biological Efficiency(4) to carbon ions. This large collection of data should increase our knowledge in glioblastoma radiobiology in order to better understand, and to later individualize, appropriate radiotherapy treatment for patients who are good candidates. PMID:25657111

  17. Tailoring dynamic magnetic characteristics of F e60A l40 films through ion irradiation

    NASA Astrophysics Data System (ADS)

    Tahir, N.; Bali, R.; Gieniusz, R.; Mamica, S.; Gollwitzer, J.; Schneider, T.; Lenz, K.; Potzger, K.; Lindner, J.; Krawczyk, M.; Fassbender, J.; Maziewski, A.

    2015-10-01

    Magnetization dynamics in F e60A l40 thin films possessing depth-varying saturation magnetization (MS) have been studied experimentally and theoretically. Variation in MS was achieved by irradiation of 40 nm thick, chemically ordered (B2 phase) F e60A l40 films with N e+ ions with energies between 0-30 keV. The initial B2 phase is paramagnetic, and as the penetrating ions cause chemical disordering, the ion-affected region transforms to the ferromagnetic A2 phase. The effective ferromagnetic thickness and the depth of the A2/B2 phase boundary depend on the ion energy (E ); the effective thicknesses are 8.5 and 40 nm, respectively, for E =2.5 and 30 keV. Thermally excited spin waves in films with varying effective ferromagnetic thicknesses were analyzed by employing Brillouin light scattering and vector network analyzer ferromagnetic resonance spectroscopy. The analytical calculations are in good agreement with the experimental values and show that the observed spin-wave modes are directly related to the effective ferromagnetic thickness; films irradiated with E <15 keV only show the Damon-Eshbach mode, whereas for 15 ? E <20 keV , an additional lower frequency standing spin-wave mode is observed. In films irradiated with E ?20 keV , the Damon-Eshbach mode is observed to lie between two standing spin-wave modes. Furthermore, the A2/B2 phase boundary can be shown to act as an asymmetric pinning site. Controlling the depth of the phase boundary by varying the ion energy can be a path to manipulate spin-wave propagation in materials displaying the phenomenon of disorder induced ferromagnetism.

  18. Temperature dependence of amorphization for zirconolite and perovskite irradiated with 1 MeV krypton ions

    SciTech Connect

    White, T.J.; Ewing, R.C.; Wang, L.M.; Forrester, J.S.; Montross, C.

    1995-12-31

    A transmission electron microscope investigation was made of zirconolites and perovskites irradiated to amorphization with 1 MeV krypton ions using the HVEM-Tandem Facility at Argonne National Laboratory. Three specimens were examined -- a prototype zirconolite CaZrTi{sub 2}O{sub 7}, a gadolinium doped zirconolite Ca{sub 0.75}Gd{sub 0.50}Zr{sub 0.75}Ti{sub 2}O{sub 7} and a uranium doped zirconolite Ca{sub 0.75}U{sub 0.50}Zr{sub 0.75}Ti{sub 2}O{sub 7}. The critical amorphization dose D{sub c} was determined at several temperatures between 20K to 675K. D{sub c} was inversely proportional with temperature. For example, pure zirconolite requiring 10x the dose for amorphization at 475K compared with gadolinium zirconolite. Using an Arrhenius plot, the activation energy E{sub a} for annealing in these compounds was found to be 0.129 eV and 0.067 eV respectively. The greater ease of amorphization for the gadolinium sample is probably a reflection of this element`s large cross section for interaction with heavy ions. Uranium zirconolite was very susceptible to damage and amorphized under 4 keV argon ions during the preparation of microscope specimens. In each sample, zirconolite coexisted with minor perovskite, reduced rutile (Magneli phases) and zirconia. These phases were more resistant to ion irradiation than zirconolite. Even for high gadolinium loadings, perovskite (Ca{sub 0.8}Gd{sub 0.2}TiO{sub 3}) was 3--4 times more stable to ion irradiation than the surrounding zirconolite crystals.

  19. I-V analysis of high-energy lithium-ion-irradiated Si and GaAs solar cells

    E-print Network

    A. Meulenberg Jr; B. Jayashree; Ramani; M. C. Radhakrishna; A. K. Saif

    2007-09-07

    Space-grade Si and GaAs solar cells were irradiated with 15 and 40 MeV lithium ions. Dark-IV analysis (with and without illumination) reveals differences in the effects of such irradiation on the different cell types

  20. Densification, anisotropic deformation, and plastic flow of SiO2 during MeV heavy ion irradiation

    E-print Network

    Polman, Albert

    Densification, anisotropic deformation, and plastic flow of SiO2 during MeV heavy ion irradiation E years,1 because of the potential use of silica in nuclear reactors and waste containers, and its current results in a tensile stress in the irradiated region. Stress can be relieved by radiation enhanced plastic

  1. Xe isotopic fractionation in a cathodeless glow discharge. [for carbonaceous meteoritic composition studies

    NASA Technical Reports Server (NTRS)

    Bernatowicz, T. J.; Fahey, A. J.

    1986-01-01

    Results are reported on the isotopic composition of Xe processed in cathodeless glow discharges in rarefied air at pressures of 20-40 microns Hg, in the presence of activated charcoal and in empty pyrex containers. Residual gas phase Xe and trapped Xe were found to be fractionated, with the trapped Xe fractionated up to 1 percent per amu. A model is presented for the fractionating process in which Xe ions are simultaneously implanted and sputtered from substrate material, with a mass dependence favoring retention of the heavy isotopes in the substrate. Results of the investigation show that plasma synthesis of carbonaceous material is unnecessary for producing Xe fractionations, and that the fractionations observed in previous synthesis experiments are probably due to implantation of ions into the synthesized material.

  2. Diamond light emitting diode activated with Xe optical centers

    NASA Astrophysics Data System (ADS)

    Zaitsev, A. M.; Bergman, A. A.; Gorokhovsky, A. A.; Huang, Mengbing

    2006-02-01

    A diamond light emitting diode (LED) activated with Xe-related optical centres is reported. The device was made on a high quality single crystal CVD diamond substrate using B+ and Li+ ion implantation, subsequent implantation by Xe+ ions and vacuum annealing to 1400 °C. A diode behaviour with the rectification ratio of 105 at 100 V was achieved. The electroluminescence (EL) of the device was found to concentrate at the B+ ion doped p-type area likely as a result of dominating injection of holes. The room temperature EL spectrum in the range 450 to 850 nm was presented by a narrow band emission of the zero phonon lines 812.5 nm and 794 nm of the Xe centre on a low emission background of the 575 nm nitrogen-related centre.

  3. Ion Tracks and Microstructures in Barium Titanate Irradiated with Swift Heavy Ions: A Combined Experimental and Computational Study

    SciTech Connect

    Jiang, Weilin; Devanathan, Ramaswami; Sundgren, Christina J.; Ishimaru, Manabu; Sato, Kazuhisa; Varga, Tamas; Manandhar, Sandeep; Benyagoub, Abdenacer

    2013-12-11

    Tetragonally structured BaTiO3 single crystals were irradiated using 635 MeV 238U+ ions to fluences of 1E7, 5E10 and 1.4E12 ions/cm2 at room temperature. Subsequent sample characterizations were performed using ion channeling, x-ray diffraction (XRD), helium ion microscopy, and transmission electron microscopy. The results show that there are lattice relaxation and recovery of pre-existing defects in the irradiated samples. Various structures representing different regimes of electronic and nuclear interactions along the ion track are observed. The track on the surface has an amorphous core of up to ~10 nm in diameter, surrounded by a strained lattice structure. The core size is roughly proportional to the square root of the electronic stopping power. Satellite-like defects around the core are also present. The ring of cubic phase expected to form around the amorphous core does not appear, probably due to a reversible phase transition as confirmed by an in-situ XRD study. Modeling and simulation are also attempted to interpret the data and gain physical insights. We have developed a partial charge model for cubic BaTiO3 that reproduces its lattice constants, elastic constants, and melting temperature. Using the interatomic potential, we have performed molecular dynamics simulations of the irradiation damage in BaTiO3. The results show that an amorphous track of ~1.2 nm in radius forms under thermal energy deposition at dE(T)/dx = 5 keV/nm. At 20 keV/nm, the radius increases to ~4.5 nm with an order of magnitude increase in the number of defects. The simulation also reveals details of the bonding environments and shows that the amorphous zones produced at different dE(T)/dx values have different densities. The combined experimental and computational data suggest that there is a significant interfacial recrystallization of the as-created amorphous cores during the cooling-down stage of thermal spikes.

  4. Temperature-dependent void formation and growth at ion-irradiated nanocrystalline CeO2 Si interfaces

    SciTech Connect

    Perez-Bergquist, Alex G; Zhang, Yanwen; Varga, Tamas; Moll, Sandra; Weber, William J

    2014-01-01

    Ceria is a thermally stable ceramic that has numerous applications in the nuclear industry, including use in nuclear fuels and waste forms. Recently, interest has surged in nanostructured ceria due to its increased mechanical properties and electronic conductivity in comparison with bulk ceria and its ability to self-heal in response to energetic ion bombardment. Here, nanocrystalline ceria thin films grown over a silicon substrate are irradiated to fluences of up to 4 1016 ions/cm2 under different irradiation conditions: with differing ion species (Si+ and Ni+), different ion energies (1.0 1.5 MeV), and at varying temperatures (160 600 K). While the nanocrystalline ceria is found to exhibit exceptional radiation resistance under all tested conditions, severe ion irradiation-induced mixing, void formation, and void growth are observed at the ceria/silicon interface, with the degree of damage proving to be temperature dependent.

  5. Temperature-dependent void formation and growth at ion-irradiated nanocrystalline CeO2-Si interfaces

    NASA Astrophysics Data System (ADS)

    Perez-Bergquist, Alejandro G.; Zhang, Yanwen; Varga, Tamas; Moll, Sandra; Namavar, Fereydoon; Weber, William J.

    2014-04-01

    Ceria is a thermally stable ceramic that has numerous applications in the nuclear industry, including use in nuclear fuels and waste forms. Recently, interest has surged in nanostructured ceria due to its increased mechanical properties and electronic conductivity in comparison with bulk ceria and its ability to self-heal in response to energetic ion bombardment. Here, nanocrystalline ceria thin films grown over a silicon substrate are irradiated to fluences of up to ˜4 × 1016 ions/cm2 under different irradiation conditions: with differing ion species (Si+ and Ni+), different ion energies (1.0-1.5 MeV), and at varying temperatures (160-600 K). While the nanocrystalline ceria is found to exhibit exceptional radiation resistance under all tested conditions, severe ion irradiation-induced mixing, void formation, and void growth are observed at the ceria/silicon interface, with the degree of damage proving to be temperature dependent.

  6. The Mechanical Properties of Alumina Films Formed by Plasma Deposition and by Ion Irradiation of Sapphire

    SciTech Connect

    Barbour, J.C.; Follstaedt, D.M.; Knapp, J.A.; Linam, D.L.; Mayer, T.M.; Minor, K.G.

    1999-07-16

    This paper examines the correlation between mechanical properties and the density, phase, and hydrogen content of deposited alumina layers, and compares them to those of sapphire and amorphous alumina synthesized through ion-beam irradiation of sapphire. Alumina films were deposited using electron beam evaporation of aluminum and co-bombardment with O{sub 2}{sup +} ions (30-230 eV) from an electron cyclotron resonance (ECR) plasma. The H content and phase were controlled by varying the deposition temperature and the ion energy. Sapphire was amorphized at 84 K by irradiation with Al and O ions (in stoichiometric ratio) to a defect level of 4 dpa in order to form an amorphous layer 370 nm thick. Nanoindentation was performed to determine the elastic modulus, yield strength and hardness of all materials. Sapphire and amorphized sapphire have a higher density and exhibit superior mechanical properties in comparison to the deposited alumina films. Density was determined to be the primary factor affecting the mechanical properties, which showed only a weak correlation to the hydrogen content.

  7. Nanoscale density fluctuations in swift heavy ion irradiated amorphous P. Kluth, O. H. Pakarinen, F. Djurabekova, R. Giulian, M. C. Ridgway et al.

    E-print Network

    Nordlund, Kai

    Nanoscale density fluctuations in swift heavy ion irradiated amorphous SiO2 P. Kluth, O. H irradiation J. Appl. Phys. 111, 016102 (2012) Enhancement of impact-induced mechanoluminescence by swift heavy density fluctuations in swift heavy ion irradiated amorphous SiO2 P. Kluth,1,a) O. H. Pakarinen,2 F

  8. Au ion irradiation of various silicon carbide fiber-reinforced SiC matrix composites

    NASA Astrophysics Data System (ADS)

    Chaâbane, Nihed; Le Flem, Marion; Tanguy, Morgane; Urvoy, Stéphane; Sandt, Christophe; Dumas, Paul; Serruys, Yves

    2013-08-01

    Silicon carbide fiber-reinforced SiC matrix composites are promising candidates as fuel cladding for several concepts of Generation IV reactors and as structural materials for fusion reactors. The composites used in this study were composed of a SiC matrix obtained by chemical vapor infiltration associated with various fiber types (Tyranno Type-S, Tyranno SA Grade-3 and Hi-Nicalon Type-S) and with a PyC layer as the interphase. 12 MeV Au ions were used for irradiation up to 0.05 and 1 displacement per atom (dpa) fluences at room temperature and 800 °C. Analysis of both microstructure and composition of composites were performed by scanning electron microscopy (SEM), electron probe microanalysis and Raman spectroscopy. At room temperature and low fluence, Raman spectroscopy results showed that irradiation induces a disordered/distorted state into fibers and matrix. With increasing fluence, a total amorphization of these constituents occurs. The increase in the irradiation temperature leads to a damage recovery and partial recrystallization of samples. Image analysis performed from SEM micrographs highlights no significant change in fiber diameter and shape. However, SEM analysis suggests a longitudinal shrinkage of Tyranno Type-S fibers for the composite irradiated at 1 dpa at room temperature and 800 °C. These results are in complete agreement with conclusions from neutron irradiations suggesting an appropriate relevance of irradiations with 12 MeV Au. Image analysis did not evidence any macroscopic changes in the fibers shape or diameter. Difference in behavior of the TS fiber and the CVI-SiC matrix after irradiation at 1 dpa was evidenced through the occurrence of a step suggesting limited swelling of the TS fibers. This was attributed to a combination of basic swelling under irradiation (lead to amorphization) and previously reported shrinkage of this type of fibers (partially crystallized). On the contrary, the well crystallized and stoichiometric TSA3 and HNS fibers behaved liked the CVI-SiC matrix (similar Raman spectra and to difference in volume change). The microstructure changes suggested by Raman analysis are consistent with others investigations: irradiation at RT results in occurrence of disorder up to complete amorphization above a threshold dose but in situ defect recombination during irradiation at 800 °C results in disordered SiC only. TEM analysis along the damage profile are planned to further characterize the microstructure evolution of the constituent and explain the various behavior of the fibers.

  9. Thermal property tuning in aligned carbon nanotube films and random entangled carbon nanotube films by ion irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Chen, Di; Bykova, Julia S.; Zakhidov, Anvar A.; Wang, Xuemei; Shao, Lin

    2015-10-01

    Ion irradiation effects on thermal property changes are compared between aligned carbon nanotube (A-CNT) films and randomly entangled carbon nanotube (R-CNT) films. After H, C, and Fe ion irradiation, a focusing ion beam with sub-mm diameter is used as a heating source, and an infrared signal is recorded to extract thermal conductivity. Ion irradiation decreases thermal conductivity of A-CNT films, but increases that of R-CNT films. We explain the opposite trends by the fact that neighboring CNT bundles are loosely bonded in A-CNT films, which makes it difficult to create inter-tube linkage/bonding upon ion irradiation. In a comparison, in R-CNT films, which have dense tube networking, carbon displacements are easily trapped between touching tubes and act as inter-tube linkage to promote off-axial phonon transport. The enhancement overcomes the phonon transport loss due to phonon-defect scattering along the axial direction. A model is established to explain the dependence of thermal conductivity changes on ion irradiation parameters including ion species, energies, and current.

  10. Comparison of total dose effects on SiGe heterojunction bipolar transistors induced by different swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Sun, Ya-Bin; Fu, Jun; Xu, Jun; Wang, Yu-Dong; Zhou, Wei; Zhang, Wei; Cui, Jie; Li, Gao-Qing; Liu, Zhi-Hong

    2014-11-01

    The degradations in NPN silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) were fully studied in this work, by means of 25-MeV Si, 10-MeV Cl, 20-MeV Br, and 10-MeV Br ion irradiation, respectively. Electrical parameters such as the base current (IB), current gain (?), neutral base recombination (NBR), and Early voltage (VA) were investigated and used to evaluate the tolerance to heavy ion irradiation. Experimental results demonstrate that device degradations are indeed radiation-source-dependent, and the larger the ion nuclear energy loss is, the more the displacement damages are, and thereby the more serious the performance degradation is. The maximum degradation was observed in the transistors irradiated by 10-MeV Br. For 20-MeV and 10-MeV Br ion irradiation, an unexpected degradation in IC was observed and Early voltage decreased with increasing ion fluence, and NBR appeared to slow down at high ion fluence. The degradations in SiGe HBTs were mainly attributed to the displacement damages created by heavy ion irradiation in the transistors. The underlying physical mechanisms are analyzed and investigated in detail.

  11. Embedded Nanofibers Induced by High-Energy Ion Irradiation of Bulk GaSb

    SciTech Connect

    Alejandro , Perez-Bergqu G.; Zhu, Sha; Sun, Kai; Xiang, Xia; Zhang, Yanwen; Wang, Lumin M.

    2008-08-01

    Semiconductor nanostructures have attracted widespread attention for their unique quantum-confined nanoscale properties. In particular, the luminescence properties of nanoscale semiconductors are seen as a key to the future of optoelectronic microdevice fabrication. Although numerous techniques exist for the formation and modification of nanostructures on material surfaces, fabrication of such structures embedded within the material have proved elusive. In this work, we present the formation of embedded nanofiber layers within GaSb by high energy Au+ ion irradiation, and we analyze the distinct regions of the fiber layers formed as a result. Using growth models for low energy ions, a modified growth model is presented to interpret the presence of these observed fiber regimes. Furthermore, methods for tailoring the relative sizes of the fiber layers are presented. An additional model is proposed to account for the removal of the surface layer at increasing ion fluence.

  12. Synthesis of confined electrically conducting carbon nanowires by heavy ion irradiation of fullerene thin film

    SciTech Connect

    Kumar, Amit; Avasthi, D. K.; Tripathi, A.; Kabiraj, D.; Singh, F.; Pivin, J. C.

    2007-01-01

    Conducting nanowires parallel to each other, embedded in fullerene matrix are synthesized by high energy heavy ion irradiation of thin fullerene film at low fluence (up to 5x10{sup 11} ions/cm{sup 2}). The conductivity of the conducting zone is about seven orders of magnitude higher than that of the fullerene matrix. The conducting nanowires are evidenced by conducting atomic force microscopy. The typical diameter of the conducting tracks is observed to be about 40-100 nm. The creation of conducting wires is explained by transformation of fullerene to conducting form of carbon in the ion track, surrounded by the polymerized zone. The polymerization of fullerene is evidenced by Fourier transform infrared spectroscopy.

  13. Damage Processes In MgO Irradiated With Medium-energy Heavy Ions

    SciTech Connect

    Moll, Sandra J.; Zhang, Y.; Debelle, A.; Thome, Lionel; Crocombette, J.-P.; Zhu, Zihua; Jagielski, Jacek; Weber, William J.

    2015-04-01

    The micro-structural modifications produced in MgO single crystals exposed to medium-energy heavy ions (1.2-MeV Au) were investigated using Rutherford backscattering spectrometry in channeling geometry coupled to Monte-Carlo analyses, secondary ion mass spectrometry, X-ray diffraction and transmission electron microscopy. The damage accumulation and the elastic strain variation were interpreted in the framework of the multi-step damage accumulation (MSDA) model. Both build-ups follow a multi-step process similar to that recently observed for ion-irradiated yttria-stabilized zirconia (YSZ) single crystals. However, in MgO, an unexpectedly high disorder level occurs far beyond the theoretical damage distribution. These results strongly suggest that the migration of defects created in the near-surface layer is most likely at the origin of the broadening of the damage depth distribution in MgO.

  14. Density of hydroxyl radicals generated in an aqueous solution by irradiating carbon-ion beam.

    PubMed

    Matsumoto, Ken-ichiro; Ueno, Megumi; Nakanishi, Ikuo; Anzai, Kazunori

    2015-01-01

    The density of hydroxyl radicals (·OH) produced in aqueous samples by exposure to X-ray or carbon-ion beams was investigated. The generation of ·OH was detected by the electron paramagnetic resonance (EPR) spin-trapping technique using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as the spin-trapping agent. When the concentration of DMPO is in excess of the generated ·OH, the production of DMPO-OH (spin-trapped ·OH) should be saturated. Reaction mixtures containing several concentrations (0.5-1685?mM) of DMPO were then irradiated by a 32?Gy 290?MeV carbon-ion beam (C290-beam) or X-ray. C290-beam irradiation was performed at the Heavy-Ion Medical Accelerator in Chiba (HIMAC, National Institute of Radiological Sciences, Chiba, Japan), applying different linear energy transfers (LET) (20-169?keV/µm). The amount of DMPO-OH in the irradiated samples was detected by EPR spectroscopy. The generation of DMPO-OH increased with the concentration of initial DMPO, displayed a shoulder around 3.3?mM DMPO, and reached a plateau. This plateau suggests that the generated ·OH were completely trapped. Another linear increase in DMPO-OH measured in solutions with higher DMPO concentrations suggested very dense ·OH generation (>1.7?M). Generation of ·OH is expected to be localized on the track of the radiation beam, because the maximum concentration of measured DMPO-OH was 40?µM. These results suggested that both sparse (?3.3?mM) and dense (>1.7?M) ·OH generation occurred in the irradiated samples. The percentage of dense ·OH generation increased with increasing LET. Different types of dense ·OH generation may be expected for X-ray and C290-beams. PMID:25757490

  15. Antiradiation vaccine: Technology and development of prophylaxis, prevention and treatment of biological consequences from Heavy Ion irradiation.

    NASA Astrophysics Data System (ADS)

    Popov, Dmitri; Maliev, Vecheslav

    Introduction: An anti-radiation vaccine could be an important part of a countermeasures reg-imen for effective radioprotection, immunoprophylaxis and immunotherapy of the acute radi-ation syndromes (ARS) after gamma-irradiation, neutron irradiation or heavy ion irradiation. Reliable protection of non-neoplastic regions of patients with different forms of cancer which undergo to heavy ion therapy ( e.g. Hadron-therapy) can significantly extend the efficiency of the therapeutic course. The protection of cosmonauts astronauts from the heavy ion ra-diation component of space radiation with specific immunoprophylaxis by the anti-radiation vaccine may be an important part of medical management for long term space missions. Meth-ods and experiments: 1. The Antiradiation Vaccine preparation -standard (mixture of toxoid form of Radiation Toxins -SRD-group) which include Cerebrovascular RT Neurotoxin, Car-diovascular RT Neurotoxin, Gastrointestinal RT Neurotoxin, Hematopoietic RT Hematotoxin. Radiation Toxins Specific Radiation Determinant Group were isolated from a central lymph of gamma-irradiated animals with Cerebrovascular, Cardiovascular, Gastrointestiinal, Hematopoi-etic forms of ARS. Devices for ?-radiation are "Panorama", "Puma". 2. Heavy ion exposure was accomplished at Department of Scientific Research Institute of Nuclear Physics, Dubna, Russia. The heavy ions irradiation was generated in heavy ion (Fe56) accelerator -UTI. Heavy Ion linear transfer energy -2000-2600 KeV mkm, 600 MeV U. Absorbed Dose -3820 Rad. 3. Experimental Design: Rabbits from all groups were irradiated by heavy ion accelerator. Group A -control -10 rabbits; Group B -placebo -5 rabbits; Group C -radioprotectant Cystamine (50 mg kg)-5 rabbits, 15 minutes before irradiation -5 rabbits; Group D -radioprotectant Gammafos (Amifostine -400mg kg ), -5 rabbits; Group E -Antiradiation Vaccine: subcuta-neus administration or IM -2 ml of active substance, 14 days before irradiation -5 rabbits. 4. Results: Group A -100% mortality within two hours after heavy ion irradiation with clinical symptoms of the acute cerebrovascular and cardiovascular syndromes. Group B -100% mortal-ity within 15 hours following irradiation. Group C -100% mortality within 14-15 hours after irradiation. Group D -100% mortality within 15-16 hours after irradiation. In groups A-D, development of the acute radiation cerebrovascular and cardiovascular syndromes as well as ex-tensive burns of skin caused rapid death. Group E -100% mortality in 280-290 hours (12 days) following heavy ion irradiation while animals were exhibiting a combination or individual forms of the acute cerebrovascular, cardiovascular, and gastrointestinal forms and focal skin burns. Discussion: The Antiradiation Vaccine (ARV) and specific immune-prophylaxis are an effective method of neutralization of Radiation Toxins. Vaccination with the ARV significantly extended the survival time after irradiation with heavy ions from two hours up to 300 hours. Clinical signs, clinical features, symptoms were somewhat attenuated. Degree of clinical forms of the Acute Radiation Syndromes were diminished in their severity. Groups A-D demonstrated an extremely severe degree (Degree 4) of Cerebrovascular and Cardiovascular forms of the Acute Radiation Syndromes and lethality 100% was registered in a short time after irradiation. Radi-ation induced burns in this groups (with Cutaneous sub-syndrome of ARS -Degree 4) that were deep with extensive and total dysfunction and possible muscle involvement developed. Animals from group E -Radioprotectant -anti-radiation vaccine had demonstrated later development of the severe Degree 3 or even Degree 2-3 forms of Cerebrovascular and Cardiovascular forms of the ARS and a survival time of irradiated animals was significantly prolonged. Cutaneous sub-syndrome developed in Degree 3 or Degree 2-3. Our results have demonstrated the potential radioprotection efficacy of specific immune-prophylaxis with the Antiradiation vaccine against heavy ion irradiation.

  16. Effects of Prenatal Irradiation with an Accelerated Heavy-Ion Beam on Postnatal Development in Rats

    NASA Astrophysics Data System (ADS)

    Wang, B.; Murakami, M.; Eguchi-Kasai, K.; Nojima, K.; Shang, Y.; Tanaka, K.; Fujita, K.; Coffigny, H.; Hayata, I.

    Effects on postnatal neurophysiological development in offspring were studied following exposure of pregnant Wistar rats to accelerated neon-ion beams with a LET value of about 30 keV mu m at a dose range from 0 1 Gy to 2 0Gy on the 15th day of gestation The age at which four physiologic markers appeared and five reflexes were acquired was examined prior to weaning Gain in body weight was monitored until the offspring were 3 months old Male offspring were evaluated as young adults using two behavioral tests The effects of X-rays at 200 kVp measured for the same biological end points were studied for comparison Our previous study on carbon-ion beams with a LET value of about 13 keV mu m was also cited to elucidate a possible LET-related effect For most of the endpoints at early age significant alteration was even observed in offspring prenatally received 0 1 Gy of accelerated neon ions while neither X rays nor carbon-ions under the same dose resulted in such a significant alteration compared to that from the sham-irradiated dams All offspring whose mothers received 2 0 Gy died prior to weaning Offspring from dams irradiated with accelerated neon ions generally showed higher incidences of prenatal death and preweaning mortality markedly delayed accomplishment in their physiological markers and reflexes and gain in body weight compared to those exposed to X-rays or carbon ions at doses of 0 1 to 1 5 Gy Significantly reduced ratios of main organ weight to body weight at postnatal ages of 30 60 and 90 days were also observed

  17. The first narrow-band XeCl-excilamp application for complex psoriasis curing

    NASA Astrophysics Data System (ADS)

    Dmitruck, Vadim S.; Sosnin, Edward A.; Obgol'tz, Irina A.

    2006-05-01

    Clinical efficiency estimation of XeCl-excilamp application for psoriasis curing in comparison with other methods of phototherapy for has been carried out for the first time. Curing psoriasis by XeCl-excilamp assistance is shown to be an effective and present-date method. Such a phototherapy advantages suggested are the good tolerance, and absence of intact skin irradiation. The use of chemicals is no longer relevant, and the total doze of irradiation happens to be rather low.

  18. Structural, morphological and electrical studies of lithium ion irradiated sodium potassium niobate single crystal grown by flux method

    SciTech Connect

    Saravanan, R.; Rajesh, D.; Rajasekaran, S. V.; Perumal, R.; Chitra, M.; Jayavel, R.

    2013-02-05

    Single crystals of sodium potassium niobate (K{sub 0.5}Na{sub 0.5})NbO{sub 3} (KNN) were grown by flux method and crystals were irradiated with 45 MeV Li ions to modify the electrical properties. Energy of the irradiated heavy ion was lower than the threshold energy to produce columnar defect and only clusters of defect was observed. The surface morphology of the irradiated single crystals was studied using scanning electron microscope (SEM) and atomic force microscope (AFM). The results show that the surface roughness value was found to increase with increasing fluence.

  19. A review of transmission electron microscopes with in situ ion irradiation

    NASA Astrophysics Data System (ADS)

    Hinks, J. A.

    2009-12-01

    Transmission electron microscopy (TEM) with in situ ion irradiation is unique amongst experimental techniques in allowing the direct observation of the internal microstructure of materials on the nanoscale whilst they are being subjected to bombardment with energetic particles. Invaluable insights into the underlying atomistic processes at work can be gained through direct investigation of radiation induced and enhanced effects such as: phase changes and segregation; mechanical and structural changes; atomic/layer mixing and chemical disorder; compositional changes; chemical reactions; grain growth and shrinkage; precipitation and dissolution; defect/bubble formation, growth, motion, coalescence, removal and destruction; ionisation; diffusion; and collision cascades. The experimental results obtained can be used to validate the predictions of computational models which in turn can elucidate the mechanisms behind the phenomena seen in the microscope. It is 50 years since the first TEM observations of in situ ion irradiation were made by D.W. Pashley, A.E.B. Presland and J.W. Menter at the Tube Investment Laboratories in Cambridge, United Kingdom and 40 years since the first interfacing of an ion beam system with a TEM by P.A. Thackery, R.S. Nelson and H.C. Sansom at the Atomic Energy Research Establishment at Harwell, United Kingdom. In that time the field has grown with references in the literature to around thirty examples of such facilities. This paper gives an overview of the importance of the technique, especially with regard to the current challenges faced in understanding radiation damage in nuclear environments; a description of some of the important construction elements and design considerations of TEMs with in situ ion irradiation; a brief history of the development of this type of instrument; a summary of the facilities built around the world over the last half century; and finally a focus on the instruments in operation today.

  20. IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 54, NO. 8, AUGUST 2007 1963 SPICE Models of Fluorine-Ion-Irradiated

    E-print Network

    Hornsey, Richard

    IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 54, NO. 8, AUGUST 2007 1963 SPICE Models of Fluorine transistors. Using Fluorine +7 ions with an energy of 17 MeV, the effects of radiation are investigated increase after it was irradiated with fluorine ions. The ideality factor of recombination current

  1. Microstructural evolution of ferritic-martensitic steels under heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Topbasi, Cem

    Ferritic-martensitic steels are primary candidate materials for fuel cladding and internal applications in the Sodium Fast Reactor, as well as first-wall and blanket materials in future fusion concepts because of their favorable mechanical properties and resistance to radiation damage. Since microstructure evolution under irradiation is amongst the key issues for these materials in these applications, developing a fundamental understanding of the irradiation-induced microstructure in these alloys is crucial in modeling and designing new alloys with improved properties. The goal of this project was to investigate the evolution of microstructure of two commercial ferritic-martensitic steels, NF616 and HCM12A, under heavy ion irradiation at a broad temperature range. An in situ heavy ion irradiation technique was used to create irradiation damage in the alloy; while it was being examined in a transmission electron microscope. Electron-transparent samples of NF616 and HCM12A were irradiated in situ at the Intermediate Voltage Electron Microscope (IVEM) at Argonne National Laboratory with 1 MeV Kr ions to ˜10 dpa at temperatures ranging from 20 to 773 K. The microstructure evolution of NF616 and HCM12A was followed in situ by systematically recording micrographs and diffraction patterns as well as capturing videos during irradiation. In these irradiations, there was a period during which no changes are visible in the microstructure. After a threshold dose (˜0.1 dpa between 20 and 573 K, and ˜2.5 dpa at 673 K) black dots started to become visible under the ion beam. These black dots appeared suddenly (from one frame to the next) and are thought to be small defect clusters (2-5 nm in diameter), possibly small dislocation loops with Burgers vectors of either ½ or . The overall density of these defect clusters increased with dose and saturated around 6 dpa. At saturation, a steady-state is reached in which defects are eliminated and created at the same rates so that the defect density is constant. After saturation, defects constantly appeared and disappeared in a time that is shorter than the time in between frames (normally 34 ms). The average diameter and size distribution of the irradiation-induced defect clusters did not vary with dose during a single irradiation in the temperature range of 50 to 573 K in NF616, and 20 to 673 K in HCM12A. At 673 K, the defects in NF616 grew and coalesced under irradiation which led to larger average defect sizes and low defect density. At high doses extended defect structures in NF616 formed as short segments aligned along 100 directions. At 773 K, the frequency of defect formation per unit area was the lowest amongst all irradiations and all the visible defect clusters that formed eventually faded out gradually (in ˜28 seconds) leading to no net defect accumulation in NF616 even at the highest irradiation dose of 10 dpa. Under irradiation, a significant fraction of these defect clusters exhibited sudden one- dimensional jumps (over ~5nm) between 20 and 573 K, that is, some defect clusters move "or jump" along directions which is consistent with the expected Burgers vector direction of (111). Interestingly, at 673 and 773 K, defects in NF616 and HCM12A did not exhibit the sudden jumps and jerks that were frequently observed during lower temperature irradiations. No resolvable loops, voids or precipitates were formed in NF616 and HCM12A. Furthermore, no significant interaction of the irradiation induced defects with the foil surface, pre-existing dislocation network or grain boundaries was observed between 20 and 773 K. A simplified rate theory model was developed to describe the initial defect formation processes. The model is based on the reactions between intra-cascade clusters driven by the one-dimensional movement of sub-visible interstitial clusters in their glide cylinder under irradiation after detrapping from interstitial and substitutional solute atoms by cascade impact. Multiple cascade impacts on previously existing clusters allow them to gather clusters during their

  2. Ferromagnetism in 200-MeV Ag+15-ion-irradiated Co-implanted ZnO thin films

    NASA Astrophysics Data System (ADS)

    Angadi, Basavaraj; Jung, Y. S.; Choi, Won-Kook; Kumar, Ravi; Jeong, K.; Shin, S. W.; Lee, J. H.; Song, J. H.; Wasi Khan, M.; Srivastava, J. P.

    2006-04-01

    Structural, electrical resistivity, and magnetization properties of 200-MeV Ag+15-ion-irradiated Co-implanted ZnO thin films are presented. The structural studies show the presence of Co clusters whose size is found to increase with increase of Co implantation. The implanted films were irradiated with 200-MeV Ag+15 ions to fluence of 1×1012ions/cm2. The Co clusters on irradiation dissolve in the ZnO matrix. The electrical resistivity of the irradiated samples is lowered to half. The magnetization hysteresis measurements show ferromagnetic behavior at 300K, and the coercive field increases with the Co implantation. The ferromagnetism at room temperature is confirmed by magnetic force microscopy measurements. The results are explained on the basis of the close interplay between the electrical and the magnetic properties.

  3. Nano-welding and junction formation in hydrogen titanate nanowires by low-energy nitrogen ion irradiation.

    PubMed

    Dhal, Satyanarayan; Chatterjee, Shyamal; Sarkar, Subhrangsu; Tribedi, Lokesh C; Bapat, Rudheer; Ayyub, Pushan

    2015-06-12

    Crystalline hydrogen titanate (H2Ti3O7) nanowires were irradiated with N(+) ions of different energies and fluences. Scanning electron microscopy reveals that at relatively lower fluence the nanowires are bent and start to adhere strongly to one another as well as to the silicon substrate. At higher fluence, the nanowires show large-scale welding and form a network of mainly 'X' and 'Y' junctions. Transmission electron microscopy and Raman scattering studies confirm a high degree of amorphization of the nanowire surface after irradiation. We suggest that while ion-irradiation induced defect formation and dangling bonds may lead to chemical bonding between nanowires, the large scale nano-welding and junction network formation can be ascribed to localized surface melting due to heat spike. Our results demonstrate that low energy ion irradiation with suitable choice of fluence may provide an attractive route to the formation and manipulation of large-area nanowire-based devices. PMID:25990259

  4. Fe and O EELS Studies of Ion Irradiated Murchison CM2 Carbonaceous Chondrite Matrix

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Christofferson, R.; Dukes, C. A.; Baragiola, R. A.; Rahman, Z.

    2015-01-01

    Introduction: The physical and chemical response of hydrated carbonaceous chondrite materials to space weathering processes is poorly understood. Improving this understanding is a key part of establishing how regoliths on primitive carbonaceous asteroids respond to space weathering processes, knowledge that supports future sample return missions (Hayabusa 2 and OSIRISREx) that are targeting objects of this type. We previously reported on He+ irradiation of Murchison matrix and showed that the irradiation resulted in amorphization of the matrix phyllosilicates, loss of OH, and surface vesiculation. Here, we report electron energy-loss spectroscopy (EELS) measurements of the irradiated material with emphasis on the Fe and O speciation. Sample and Methods: A polished thin section of the Murchison CM2 carbonaceous chondrite was irradiated with 4 kilovolts He(+) (normal incidence) to a total dose of 1 x 10(exp 18) He(+) per square centimeter. We extracted thin sections from both irradiated and unirradiated regions in matrix using focused ion beam (FIB) techniques with electron beam deposition for the protective carbon strap to minimize surface damage artifacts from the FIB milling. The FIB sections were analyzed using a JEOL 2500SE scanning and transmission electron microscope (STEM) equipped with a Gatan Tridiem imaging filter. EELS spectra were collected from 50 nanometer diameter regions with an energy resolution of 0.7 electronvolts FWHM at the zero loss. EELS spectra were collected at low electron doses to minimize possible artifacts from electron-beam irradiation damage. Results and Discussion: Fe L (sub 2,3) EELS spectra from matrix phyllosilicates in CM chondrites show mixed Fe(2+)/Fe(3+) oxidation states with Fe(3+)/Sigma Fe approximately 0.5. Fe L(sub 2,3) spectra from the irradiated/ amorphized matrix phyllosilicates show higher Fe(2+)/Fe(3+) ratios compared to spectra obtained from pristine material at depths beyond the implantation/amorphization layer. We also obtained O Ka spectra from phyllosilicates in both regions of the sample. The O Ka spectra show a pre-edge feature at approximately 530.5 electronvolts that is related to O 2p states hybridized with Fe 3d states. The intensity ratio of the O Ka pre-edge peak relative to the main part of the O Ka edge (that results from transitions of O 1s to 2p states) is lower in the irradiated layer compared to the pristine material and may reflect the loss of O (as OH) as was observed by IR spectroscopy. Conclusions: In addition to amorphization and OH loss, EELS spectra of He(+) irradiated matrix phyllosilicates in Murchison show that some of the Fe(3+) is reduced to Fe(2+). Spectral deconvolution is underway to extract quantitative ratios from the EELS spectra.

  5. Radiation tolerant nanocrystalline ZrN films under high dose heavy-ion irradiations

    NASA Astrophysics Data System (ADS)

    Jiao, L.; Yu, K. Y.; Chen, D.; Jacob, C.; Shao, L.; Zhang, X.; Wang, H.

    2015-04-01

    ZrN, a refractory ceramic material, finds many potential applications in advanced nuclear reactors. However, the grain size dependent radiation response in nanocrystalline (nc) ZrN under high dose heavy ion irradiation has not yet been studied to date. Here, we compare the radiation response of nc-ZrN films (with a respective average grain size of ˜9 and 31 nm) to Fe2+ ion irradiations up to a damage level of 10 displacements-per-atom (dpa). The ZrN film with the average grain size of 9 nm shows prominently enhanced radiation tolerance as evidenced by suppressed grain growth, alleviated radiation softening, as well as reduced variation in electrical resistivity. In contrast, ZrN with the larger average grain size of 31 nm shows prominent radiation softening and resistivity increase, attributed to the high density of defect cluster formed inside the grains. The influence of grain boundaries on enhanced irradiation tolerance in nc-ZrN is discussed.

  6. Radiation tolerant nanocrystalline ZrN films under high dose heavy-ion irradiations

    SciTech Connect

    Jiao, L.; Wang, H.; Yu, K. Y.; Chen, D.; Jacob, C.; Shao, L.; Zhang, X.

    2015-04-14

    ZrN, a refractory ceramic material, finds many potential applications in advanced nuclear reactors. However, the grain size dependent radiation response in nanocrystalline (nc) ZrN under high dose heavy ion irradiation has not yet been studied to date. Here, we compare the radiation response of nc-ZrN films (with a respective average grain size of ?9 and 31?nm) to Fe{sup 2+} ion irradiations up to a damage level of 10 displacements-per-atom (dpa). The ZrN film with the average grain size of 9?nm shows prominently enhanced radiation tolerance as evidenced by suppressed grain growth, alleviated radiation softening, as well as reduced variation in electrical resistivity. In contrast, ZrN with the larger average grain size of 31?nm shows prominent radiation softening and resistivity increase, attributed to the high density of defect cluster formed inside the grains. The influence of grain boundaries on enhanced irradiation tolerance in nc-ZrN is discussed.

  7. The influence of microstructure on blistering and bubble formation by He ion irradiation in Al alloys

    NASA Astrophysics Data System (ADS)

    Soria, S. R.; Tolley, A.; Sánchez, E. A.

    2015-12-01

    The influence of microstructure and composition on the effects of ion irradiation in Al alloys was studied combining Atomic Force Microscopy, Scanning Electron Microscopy and Transmission Electron Microscopy. For this purpose, irradiation experiments with 20 keV He+ ions at room temperature were carried out in Al, an Al-4Cu (wt%) supersaturated solid solution, and an Al-5.6Cu-0.5Si-0.5Ge (wt.%) alloy with a very high density of precipitates, and the results were compared. In Al and Al-4Cu, He bubbles were found with an average size in between 1 nm and 2 nm that was independent of fluence. The critical fluence for bubble formation was higher in Al-4Cu than in Al. He bubbles were also observed below the critical fluence after post irradiation annealing in Al-4Cu. The incoherent interfaces between the equilibrium ? phase and the Al matrix were found to be favorable sites for the formation of He bubbles. Instead, no bubbles were observed in the precipitate rich Al-5.6Cu-0.5Si-0.5Ge alloy. In all alloys, blistering was observed, leading to surface erosion by exfoliation. The blistering effects were more severe in the Al-5.6Cu-0.5Si-0.5Ge alloy, and they were enhanced by increasing the fluence rate.

  8. Cavity morphology in a Ni based superalloy under heavy ion irradiation with hot pre-injected helium. II

    NASA Astrophysics Data System (ADS)

    Zhang, He; Yao, Zhongwen; Daymond, Mark R.; Kirk, Marquis A.

    2014-03-01

    In the current investigation, TEM in-situ heavy ion (1 MeV Kr2+) irradiation with helium pre-injected at elevated temperature (400 °C) was conducted to simulate in-reactor neutron irradiation induced damage in CANDU spacer material Inconel X-750, in an effort to understand the effects of helium on irradiation induced cavity microstructures. Three different quantities of helium, 400 appm, 1000 appm, and 5000 appm, were pre-injected directly into TEM foils at 400 °C. The samples containing helium were then irradiated in-situ with 1 MeV Kr2+ at 400 °C to a final dose of 5.4 dpa (displacement per atom). Cavities were formed from the helium injection solely and the cavity density and size increased with increasing helium dosage. In contrast to previous heavy ion irradiations with cold pre-injected helium, heterogeneous nucleation of cavities was observed. During the ensuing heavy ion irradiation, dynamical observation showed noticeable size increase in cavities which nucleated close to the grain boundaries. A "bubble-void" transformation was observed after Kr2+ irradiation to high dose (5.4 dpa) in samples containing 1000 appm and 5000 appm helium. Cavity distribution was found to be consistent with in-reactor neutron irradiation induced cavity microstructures. This implies that the distribution of helium is greatly dependent on the injection temperature, and helium pre-injection at high temperature is preferred for simulating the migration of the transmutation produced helium.

  9. Cavity morphology in a Ni based superalloy under heavy ion irradiation with hot pre-injected helium. II

    SciTech Connect

    Zhang, He; Yao, Zhongwen Daymond, Mark R.; Kirk, Marquis A.

    2014-03-14

    In the current investigation, TEM in-situ heavy ion (1?MeV Kr{sup 2+}) irradiation with helium pre-injected at elevated temperature (400?°C) was conducted to simulate in-reactor neutron irradiation induced damage in CANDU spacer material Inconel X-750, in an effort to understand the effects of helium on irradiation induced cavity microstructures. Three different quantities of helium, 400 appm, 1000 appm, and 5000 appm, were pre-injected directly into TEM foils at 400?°C. The samples containing helium were then irradiated in-situ with 1?MeV Kr{sup 2+} at 400?°C to a final dose of 5.4 dpa (displacement per atom). Cavities were formed from the helium injection solely and the cavity density and size increased with increasing helium dosage. In contrast to previous heavy ion irradiations with cold pre-injected helium, heterogeneous nucleation of cavities was observed. During the ensuing heavy ion irradiation, dynamical observation showed noticeable size increase in cavities which nucleated close to the grain boundaries. A “bubble-void” transformation was observed after Kr{sup 2+} irradiation to high dose (5.4?dpa) in samples containing 1000 appm and 5000 appm helium. Cavity distribution was found to be consistent with in-reactor neutron irradiation induced cavity microstructures. This implies that the distribution of helium is greatly dependent on the injection temperature, and helium pre-injection at high temperature is preferred for simulating the migration of the transmutation produced helium.

  10. Dependence of cross sections for multi-electron loss by 6 mev/amu xe18+ ions on target atomic number 

    E-print Network

    Peng, Yong

    2004-09-30

    It has been proposed to use heavy ion beams with energies around 10 MeV/amu, masses around 200, and average charges of 1+ as a driver for inertial fusion reactor. Current designs require the beams to travel through a region where the background gas...

  11. Charge-exchange EUV spectroscopy in collisions of Xe{sup q+} (q=7-9) with rare gases

    SciTech Connect

    Tanuma, H.; Ohashi, H.; Yamamoto, N.; Kato, D.; Murakami, I.; Fujioka, S.; Nishimura, H.; Nishihara, K.

    2011-10-15

    Extreme ultraviolet (EUV) emission spectra have been measured in charge exchange collisions between Xe{sup q+} (q=7--9) and rare gases at an energy of 20 q keV. We have observed 4, 22, and 39 lines in collisions of Xe{sup 7+}, Xe{sup 8+}, and Xe{sup 9+}. Of these emission lines, four lines of Xe vii, eight lines of Xe viii, and nine lines of Xe ix correspond to newly observed transitions. The identification procedure is described in detail. The aim of this work is to obtain spectroscopic data for multiply charged Xe ions. In addition, the electron capture mechanism is also discussed using the crude classical over-the-barrier model to understand the target dependence of the emission spectra.

  12. Late Effects of Heavy Ion Irradiation on Ex Vivo Osteoblastogenesis and Cancellous Bone Microarchitecture

    NASA Technical Reports Server (NTRS)

    Tran, Luan Hoang; Alwood, Joshua; Kumar, Akhilesh; Limoli, C. L.; Globus, Ruth

    2012-01-01

    Prolonged spaceflight causes degeneration of skeletal tissue with incomplete recovery even after return to Earth. We hypothesize that heavy ion irradiation, a component of Galactic Cosmic Radiation, damages osteoblast progenitors and may contribute to bone loss during long duration space travel beyond the protection of the Earth's magnetosphere. Male, 16 week old C57BL6/J mice were exposed to high LET (56 Fe, 600MeV) radiation using either low (5 or 10cGy) or high (50 or 200cGy) doses at the NASA Space Radiation Lab and were euthanized 3 - 4, 7, or 35 days later. Bone structure was quantified by microcomputed tomography (6.8 micron pixel size) and marrow cell redox assessed using membrane permeable, free radical sensitive fluorogenic dyes. To assess osteoblastogenesis, adherent marrow cells were cultured ex vivo, then mineralized nodule formation quantified by imaging and gene expression analyzed by RT PCR. Interestingly, 3 - 4 days post exposure, fluorogenic dyes that reflect cytoplasmic generation of reactive nitrogen/oxygen species (DAF FM Diacetate or CM H2DCFDA) revealed irradiation (50cGy) reduced free radical generation (20-45%) compared to sham irradiated controls. Alternatively, use of a dye showing relative specificity for mitochondrial superoxide generation (MitoSOX) revealed an 88% increase compared to controls. One week after exposure, reactive oxygen/nitrogen levels remained lower(24%) relative to sham irradiated controls. After one month, high dose irradiation (200 cGy) caused an 86% decrement in ex vivo nodule formation and a 16-31% decrement in bone volume to total volume and trabecular number (50, 200cGy) compared to controls. High dose irradiation (200cGy) up regulated expression of a late osteoblast marker (BGLAP) and select genes related to oxidative metabolism (Catalase) and DNA damage repair (Gadd45). In contrast, lower doses (5, 10cGy) did not affect bone structure or ex vivo nodule formation, but did down regulate iNOS by 0.54 - 0.58 fold. Thus, both low and high doses of heavy ion irradiation cause time dependent, adaptive changes in redox state within marrow cells but only high doses (50, 200cGy) inhibit osteoblastogenesis and cause cancellous bone loss. We conclude space radiation has the potential to cause persistent damage to bone marrow derived stem and progenitor cells for osteoblasts despite adaptive changes in cellular redox state.

  13. Sealing behaviour and hall conductivity of mixed-state hall effect in heavy-ion irradiated YBa{sub 2}Cu{sub 3}O{sub 7} crystals

    SciTech Connect

    Kim, D.H.; Shim, S.Y. |; Kang, W.N.

    1995-12-31

    The Hall effect ({rho}{sub xy}) and longitudinal resistivity ({rho}{sub xx}) measured in YBa{sub 2}Cu{sub 3}O{sub 7} crystals before and after the irradiation of Sn and Xe ions. We found a clear evidence that the strong pinning induced by the columnar defects not only modifies the scaling behavior between the Hall resistivity {rho}{sub xy} and longitudinal resistivity {rho}{sub xx} but also affects the temperature dependence of the Hall conductivity. For the irradiated crystals with columnar defects, the scaling exponent {beta} of {rho}{sub xy} = A{rho}{sub xx}{sup {beta}} was found to be {beta} = 1.55 {+-} 0.1, whereas {beta} of the unirradiated one was larger than 1.8. In case of the Hall conductivity, the pinning strength dependence was also observed. The Hall conductivity after irradiation exhibited a clear deviation from that of the unirradiated crystal at low temperatures. These results are in a good agreement with the work by Wang et al. in which pinning plays an important role.

  14. Grain growth in ZrFe multilayers under in situ ion irradiation A.T. Motta a,*, A. Paesano Jr. b

    E-print Network

    Motta, Arthur T.

    Transmission electron microscopy (TEM) observations during in situ ion irradiation were used to study grain irradiation in the intermediate voltage electron microscope (IVEM) at Argonne National Laboratory±Fe multilayer samples were prepared and characterized with Rutherford backscattering Nuclear Instruments

  15. Effect of ion beam irradiation on the structure of ZnO films deposited by a dc arc plasmatron

    SciTech Connect

    Penkov, Oleksiy V.; Lee, Heon-Ju; Plaksin, Vadim Yu.; Ko, Min Gook; Joa, Sang Beom; Yim, Chan Joo

    2008-02-15

    The deposition of polycrystalline ZnO film on a cold substrate was performed by using a plasmatron in rough vacuum condition. Low energy oxygen ion beam generated by a cold cathode ion source was introduced during the deposition process. The change of film property on the ion beam energy was checked. It is shown that irradiation by 200 eV ions improves crystalline structure of the film. Increasing of ion beam energy up to 400 eV leads to the degradation of a crystalline structure and decreases the deposition rate.

  16. Effect of cumulated dose on hydrogen emission from polyethylene irradiated under oxidative atmosphere using gamma rays and ion beams

    NASA Astrophysics Data System (ADS)

    Ferry, M.; Pellizzi, E.; Boughattas, I.; Fromentin, E.; Dauvois, V.; de Combarieu, G.; Coignet, P.; Cochin, F.; Ngono-Ravache, Y.; Balanzat, E.; Esnouf, S.

    2016-01-01

    This work reports the effect of very high doses, up to 10 MGy, on the H2 emission from high density polyethylene (HDPE) irradiated with gamma rays and ion beams, in the presence of oxygen. This was obtained through a two-step procedure. First, HDPE films were pre-aged, at different doses, using either gamma rays or ion beams. In the second step, the pre-aged samples were irradiated in closed glass ampoules for gas quantification, using the same beam type as for pre-ageing. The hydrogen emission rate decreases when dose increases for both gamma rays and ion beams. However, the decreasing rate appears higher under gamma rays than under ion beam irradiations and this is assigned to a lesser oxidation level under the latter. Herein, we show the effectiveness of the radiation-induced defects scavenging effect under oxidative atmosphere, under low and high excitation densities.

  17. Single phase formation of Co-implanted ZnO thin films by swift heavy ion irradiation: Optical studies

    SciTech Connect

    Kumar, Ravi; Singh, Fouran; Angadi, Basavaraj; Choi, Ji-Won; Choi, Won-Kook; Jeong, Kwangho; Song, Jong-Han; Khan, M. Wasi; Srivastava, J. P.; Kumar, Ajay; Tandon, R. P.

    2006-12-01

    Low temperature photoluminescence and optical absorption studies on 200 MeV Ag{sup +15} ion irradiated Co-implanted ZnO thin films were studied. The Co clusters present in as implanted samples were observed to be dissolved using 200 MeV Ag{sup +15} ion irradiation with a fluence of 1x10{sup 12} ions/cm{sup 2}. The photoluminescence spectrum of pure ZnO thin film was characterized by the I{sub 4} peak due to the neutral donor bound excitons and the broad green emission. The Co-doped ZnO films show three sharp levels and two shoulders corresponding to 3t{sub 2g} and 2e{sub g} levels of crystal field splitted Co d orbitals, respectively. The ultraviolet-visible absorption spectroscopy also shows the systematic variation of band gap after 200 MeV Ag{sup +15} ion irradiation.

  18. Ion irradiation studies on the void swelling behavior of a titanium modified D9 alloy

    NASA Astrophysics Data System (ADS)

    Balaji, S.; Mohan, Sruthi; Amirthapandian, S.; Chinnathambi, S.; David, C.; Panigrahi, B. K.

    2015-12-01

    The sensitivity of Positron Annihilation Spectroscopy (PAS) for probing vacancy defects and their environment is well known. Its applicability in determination of swelling and the peak swelling temperature was put to test in our earlier work on ion irradiated D9 alloys [1]. Upon comparison with the peak swelling temperature determined by conventional step height measurements it was found that the peak swelling temperature determined using PAS was 50 K higher. It was conjectured that the positrons trapping in the irradiation induced TiC precipitation could have caused the shift. In the present work, D9 alloys have been implanted with 100 appm helium ions and subsequently implanted with 2.5 MeV Ni ions up to peak damage of 100 dpa. The nickel implantations have been carried out through a range of temperatures between 450 °C and 650 °C. The evolution of cavities and TiC precipitates at various temperatures has been followed by TEM and this report provides an experimental verification of the conjecture.

  19. Chromosome aberration yields and apoptosis in human lymphocytes irradiated with Fe-ions of differing LET

    NASA Astrophysics Data System (ADS)

    Lee, R.; Nasonova, E.; Ritter, S.

    In the present paper the relationship between cell cycle delays induced by Fe-ions of differing LET and the aberration yield observable in human lymphocytes at mitosis was examined. Cells of the same donor were irradiated with 990 MeV/n Fe-ions (LET = 155 keV/?m), 200 MeV/n Fe-ions (LET = 440 keV/?m) and X-rays and aberrations were measured in first cycle mitoses harvested at different times after 48 84 h in culture and in prematurely condensed G2-cells (PCCs) collected at 48 h using calyculin A. Analysis of the time-course of chromosomal damage in first cycle metaphases revealed that the aberration frequency was similar after X-ray irradiation, but increased two and seven fold after exposure to 990 and 200 MeV/n Fe-ions, respectively. Consequently, RBEs derived from late sampling times were significantly higher than those obtained at early times. The PCC-data suggest that the delayed entry of heavily damaged cells into mitosis results especially from a prolonged arrest in G2. Preliminary data obtained for 4.1 MeV/n Cr-ions (LET = 3160 keV/?m) revealed, that these delays are even more pronounced for low energy Fe-like particles. Additionally, for the different radiation qualities, BrdU-labeling indices and apoptotic indices were determined at several time-points. Only the exposure to low energy Fe-like particles affected the entry of lymphocytes into S-phase and generated a significant apoptotic response indicating that under this particular exposure condition a large proportion of heavily damaged cells is rapidly eliminated from the cell population. The significance of this observation for the estimation of the health risk associated with space radiation remains to be elucidated.

  20. Swift heavy ion irradiation of Pt nanocrystals: II. Structural changes and H desorption

    SciTech Connect

    Giulian, R.; Araujo, L.L.; Kluth, P.; Sprouster, D.J.; Schnohr, C.S.; Byrne, A.P.; Ridgway, M.C.

    2014-09-24

    The structural properties and H desorption from embedded Pt nanocrystals (NCs) following irradiation with swift heavy ions were investigated as a function of energy and fluence. From x-ray absorption near-edge spectroscopy analysis, Pt-H bonding was identified in NCs annealed in a forming gas (95% N{sub 2} + 5% H{sub 2}) ambient. The H content decreased upon irradiation and the desorption process was NC-size dependent such that larger NCs required a higher fluence to achieve a H-free state. Pt-H bonding and NC dissolution both perturbed the NC structural parameters (coordination number, bond-length and mean-square relative displacement) as determined with extended x-ray absorption fine structure measurements.

  1. Effects of heavy ion irradiation on the thermodynamic and transport properties of YBCO

    NASA Astrophysics Data System (ADS)

    Luo, Xu; Leroux, Maxime; Mishra, Vivek; Ling, Xinsheng; Welp, Ulrich; Kwok, Wai-Kwong

    2015-03-01

    The effects of Au heavy ion irradiation (HII) on the transport and thermodynamic properties of untwined YBCO crystals irradiated to dose matching fields of B? = 6 Tesla and 1 Tesla along the crystallographic c-axis were studied by angle resolved magnetoresistivtiy and high resolution AC specific heat measurements. Results from transport measurements confirm an enhancement in the ab-plane critical current for magnetic fields aligned along the columnar defects induced by HII. Surprisingly, specific heat measurements reveal a reduction in the thermodynamic upper critical field anisotropy of YBCO by about one half in the B? = 6T crystal. Moreover, for the B? = 1T crystal, we found the formation of an anomalous peak in the critical temperature near the direction of HII which may be associated with the Bose-glass transition. Work supported by Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357.

  2. The behavior of rare-earth pyrochlores and perovskites under ion irradiation

    NASA Astrophysics Data System (ADS)

    Yudintsev, S. V.; Livshits, T. S.; Zhang, J.; Ewing, R. C.

    2015-03-01

    The behavior of samples of A2B2O7 composition under irradiation with 1-MeV Kr2+ ions was studied (A is a simulator of the REE-actinide fraction of the wastes of the treatment of used nuclear fuel and B is a quadrivalent cation of Zr, Sn, or Ti). Depending on the B elements, the samples are crystallized either in pyrochlore (Zr and Sn) or in the perovskite structural type (Ti). The matrices of the pyrochlore structure are radiation-resistant, which is shown by their high critical doses and low critical temperatures of amorphization. The phases of monocline REE titanate structure are characterized by low irradiation resistance and should be amorphized even within centuries of storage. To characterize the possibilities of their usage as matrices for waste immobilization, synthesis of materials containing short-living actinides and studies of the degree of the amorphization effect on their stability in aqueous solutions are required.

  3. Cell killing and chromatid damage in primary human bronchial epithelial cells irradiated with accelerated 56Fe ions

    NASA Technical Reports Server (NTRS)

    Suzuki, M.; Piao, C.; Hall, E. J.; Hei, T. K.

    2001-01-01

    We examined cell killing and chromatid damage in primary human bronchial epithelial cells irradiated with high-energy 56Fe ions. Cells were irradiated with graded doses of 56Fe ions (1 GeV/nucleon) accelerated with the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The survival curves for cells plated 1 h after irradiation (immediate plating) showed little or no shoulder. However, the survival curves for cells plated 24 h after irradiation (delayed plating) had a small initial shoulder. The RBE for 56Fe ions compared to 137Cs gamma rays was 1.99 for immediate plating and 2.73 for delayed plating at the D10. The repair ratio (delayed plating/immediate plating) was 1.67 for 137Cs gamma rays and 1.22 for 56Fe ions. The dose-response curves for initially measured and residual chromatid fragments detected by the Calyculin A-mediated premature chromosome condensation technique showed a linear response. The results indicated that the induction frequency for initially measured fragments was the same for 137Cs gamma rays and 56Fe ions. On the other hand, approximately 85% of the fragments induced by 137Cs gamma rays had rejoined after 24 h of postirradiation incubation; the corresponding amount for 56Fe ions was 37%. Furthermore, the frequency of chromatid exchanges induced by gamma rays measured 24 h after irradiation was higher than that induced by 56Fe ions. No difference in the amount of chromatid damage induced by the two types of radiations was detected when assayed 1 h after irradiation. The results suggest that high-energy 56Fe ions induce a higher frequency of complex, unrepairable damage at both the cellular and chromosomal levels than 137Cs gamma rays in the target cells for radiation-induced lung cancers.

  4. Effect of heavy ion irradiation on optical property of radiation-crosslinked hydroxypropyl cellulose gel containing methacrylate monomers

    NASA Astrophysics Data System (ADS)

    Hiroki, A.; Yamashita, S.; Kimura, A.; Nagasawa, N.; Taguchi, M.

    2015-12-01

    Effects of dose rate and liner energy transfer (LET) on the optical property of a polymer gel dosimeter irradiated with swift heavy ions were investigated. The polymer gel dosimeters that consist of 2-hydroxyethyl methacrylate, polyethylene glycol dimethacrylate, and tetrakis(hydroxymethyl)phosphonium chloride with radiation-crosslinked hydroxypropyl cellulose gel matrix were prepared. The dosimeters were irradiated with 150 MeV/u He ions, 290 MeV/u C ions, and 500 MeV/u Fe ions at HIMAC, and then were optically analyzed by using a UV-Vis spectrophotometer. Absorbance of the irradiated dosimeters increased with an increase in the dose up to 10 Gy. The absorbance at the dose of 5 Gy decreased with increasing dose rate in all of the heavy ions. The dosimeter irradiated with Fe ions exhibited the lowest dose response of the absorbance. It was found that the sensitivity of the dosimeters decreased with increasing dose rate as well as LET of the incident heavy ions.

  5. Formation of CO_2 and OCS after cosmic ion irradiation of icy grain mantles

    NASA Astrophysics Data System (ADS)

    Palumbo, M. E.; Baratta, G.; Fulvio, D.; Garozzo, M.; Ioppolo, S.; Kanuchova, Z.; Leto, G.; Sangiorgio, I.; Strazzulla, G.

    2011-05-01

    Molecules in the solid phase have been detected in the line of sight of quiescent molecular clouds and star forming regions as icy mantles on dust grains. Water (H_2O), carbon monoxide (CO), carbon dioxide (CO_2), methanol (CH_3OH), carbonyl sulfide (OCS), methane (CH_4), ammonia (NH_3) and sulfur dioxide (SO_2) are the most abundant observed species (e.g. Gibb et al. 2004). It is generally accepted that some of these species (such as CO) freeze out from the gas phase while others (such as water and methanol) are formed on grains after surface reactions (Ioppolo et al. 2008). CO_2 and OCS are not expected to freeze out from the gas phase and grain surface models do not account for their observed abundance (Ruffle & Herbst 2001; Garrod et al. 2007). It has been suggested that these molecules are formed after energetic processing (i.e. cosmic ion and UV irradiation) of icy grain mantles (d'Hendecourt et al. 1986; Moore et al. 1991; Palumbo & Strazzulla 1993; Ioppolo et al. 2009; Garozzo et al. 2010 ). Here we will present the results of laboratory experiments which show the formation of CO_2 and OCS after ion irradiation of relevant ice mixture at low temperature (10-20 K). We will also present the comparison between the profile of bands in laboratory spectra with those observed in space. We will show that laboratory spectra well reproduce the interstellar features and that the amount of carbon dioxide and carbonyl sulfide formed after ion irradiation can account for the observed amount towards molecular clouds.

  6. 4D particle therapy PET simulation for moving targets irradiated with scanned ion beams

    NASA Astrophysics Data System (ADS)

    Laube, K.; Menkel, S.; Bert, C.; Enghardt, W.; Helmbrecht, S.; Saito, N.; Fiedler, F.

    2013-02-01

    Particle therapy positron emission tomography (PT-PET) allows for an in vivo and in situ verification of applied dose distributions in ion beam therapy. Since the dose distribution cannot be extracted directly from the ?+-activity distribution gained from the PET scan the validation is done by means of a comparison between the reconstructed ?+-activity distributions from a PT-PET measurement and from a PT-PET simulation. Thus, the simulation software for generating PET data predicted from the treatment planning is an essential part of the dose verification routine. For the dose monitoring of intra-fractionally moving target volumes the PET data simulation needs to be upgraded by using time resolved (4D) algorithms to account correctly for the motion dependent displacement of the positron emitters. Moreover, it has to consider the time dependent relative movement between target volume and scanned beam to simulate the accurate positron emitter distribution generated during irradiation. Such a simulation program is presented which properly proceeds with motion compensated dose delivery by scanned ion beams to intra-fractionally moving targets. By means of a preclinical phantom study it is demonstrated that even the sophisticated motion-mitigated beam delivery technique of range compensated target tracking can be handled correctly by this simulation code. The new program is widely based on the 3D PT-PET simulation program which had been developed at the Helmholtz-Zentrum Dresden-Rossendorf, Germany (HZDR) for application within a pilot project to simulate in-beam PET data for about 440 patients with static tumor entities irradiated at the former treatment facility of the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany (GSI). A simulation example for a phantom geometry irradiated with a tracked 12C-ion beam is presented for demonstrating the proper functionality of the program.

  7. Mass spectrometry analysis of etch products from CR-39 plastic irradiated by heavy ions

    NASA Astrophysics Data System (ADS)

    Kodaira, S.; Nanjo, D.; Kawashima, H.; Yasuda, N.; Konishi, T.; Kurano, M.; Kitamura, H.; Uchihori, Y.; Naka, S.; Ota, S.; Ideguchi, Y.; Hasebe, N.; Mori, Y.; Yamauchi, T.

    2012-09-01

    As a feasibility study, gas chromatography-mass spectrometry (GC-MS) and matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) have been applied to analyze etch products of CR-39 plastic (one of the most frequently used solid states nuclear track detector) for the understanding of track formation and etching mechanisms by heavy ion irradiation. The etch products of irradiated CR-39 dissolved in sodium hydroxide solution (NaOH) contain radiation-induced fragments. For the GC-MS analysis, we found peaks of diethylene glycol (DEG) and a small but a definitive peak of ethylene glycol (EG) in the etch products from CR-39 irradiated by 60 MeV N ion beams. The etch products of unirradiated CR-39 showed a clear peak of DEG, but no other significant peaks were found. DEG is known to be released from the CR-39 molecule as a fragment by alkaline hydrolysis reaction of the polymer. We postulate that EG was formed as a result of the breaking of the ether bond (C-O-C) of the DEG part of the CR-39 polymer by the irradiation. The mass distribution of polyallylalcohol was obtained from the etch products from irradiated and unirradiated CR-39 samples by MALDI-MS analysis. Polyallylalcohol, with the repeating mass interval of m/z = 58 Da (dalton) between m/z = 800 and 3500, was expected to be produced from CR-39 by alkaline hydrolysis. We used IAA as a matrix to assist the ionization of organic analyte in MALDI-MS analysis and found that peaks from IAA covered mass spectrum in the lower m/z region making difficult to identify CR-39 fragment peaks which were also be seen in the same region. The mass spectrometry analysis using GC-MS and MALDI-MS will be powerful tools to investigate the radiation-induced polymeric fragments and helping to understand the track formation mechanism in CR-39 by heavy ions.

  8. Mass and Double-Beta-Decay Q Value of Xe136

    NASA Astrophysics Data System (ADS)

    Redshaw, Matthew; Wingfield, Elizabeth; McDaniel, Joseph; Myers, Edmund G.

    2007-02-01

    The atomic mass of Xe136 has been measured by comparing cyclotron frequencies of single ions in a Penning trap. The result, with 1 standard deviation uncertainty, is M(Xe136)=135.907 214 484 (11) u. Combined with previous results for the mass of Ba136 [Audi, Wapstra, and Thibault, Nucl. Phys. A 729, 337 (2003)NUPABL0375-947410.1016/j.nuclphysa.2003.11.003], this gives a Q value (M[Xe136]-M[Ba136])c2=2457.83(37)keV, sufficiently precise for ongoing searches for the neutrinoless double-beta decay of Xe136.

  9. Swift nitrogen ion irradiated waveguide lasers in Nd:YAG crystal.

    PubMed

    Ren, Yingying; Dong, Ningning; Chen, Feng; Jaque, Daniel

    2011-03-14

    We report on the fabrication, fluorescence and laser properties of optical waveguides by swift nitrogen ion irradiation in Nd:YAG crystals. The confocal micro-luminescence investigations have concluded that the fluorescence features of the bulk material have been well preserved in the waveguide. Under 808 nm optical end-pumping, continuous-wave (cw) laser oscillation at 1064.2 nm has been demonstrated with laser slope efficiencies of 16% and pump power thresholds of 38.3 mW. PMID:21445190

  10. Temperature and ion irradiation dependence of magnetic domains and microstructure in Co/Pt multilayers

    NASA Astrophysics Data System (ADS)

    Kusinski, G. J.; Thomas, G.; Denbeaux, G.; Krishnan, K. M.; Terris, B. D.

    2002-05-01

    Microstructure and magnetic properties of Co/Pt multilayers with perpendicular anisotropy were studied as a function of growth temperature (TG) and ion irradiation. With increased TG, larger columnar grain size and an improved <111> texture were observed. Up to a critical temperature (Tcrit), a monotonic increase in coercivity (HC) with TG was measured, followed by a decrease in HC with further increase in TG. Magnetic domains of films grown below Tcrit were irregular, with their submicron size decreasing gradually with increasing TG. Films grown at 390 °C>Tcrit had fine domains on the sub-100 nm length scale. Both HC and domain size were reduced after the multilayers were exposed.

  11. Hyperpolarized 131Xe NMR spectroscopy

    PubMed Central

    Stupic, Karl F.; Cleveland, Zackary I.; Pavlovskaya, Galina E.; Meersmann, Thomas

    2011-01-01

    Hyperpolarized (hp) 131Xe with up to 2.2% spin polarization (i.e., 5000-fold signal enhancement at 9.4 T) was obtained after separation from the rubidium vapor of the spin-exchange optical pumping (SEOP) process. The SEOP was applied for several minutes in a stopped-flow mode, and the fast, quadrupolar-driven T1 relaxation of this spin I = 3/2 noble gas isotope required a rapid subsequent rubidium removal and swift transfer into the high magnetic field region for NMR detection. Because of the xenon density dependent 131Xe quadrupolar relaxation in the gas phase, the SEOP polarization build-up exhibits an even more pronounced dependence on xenon partial pressure than that observed in 129Xe SEOP. 131Xe is the only stable noble gas isotope with a positive gyromagnetic ratio and shows therefore a different relative phase between hp signal and thermal signal compared to all other noble gases. The gas phase 131Xe NMR spectrum displays a surface and magnetic field dependent quadrupolar splitting that was found to have additional gas pressure and gas composition dependence. The splitting was reduced by the presence of water vapor that presumably influences xenon-surface interactions. The hp 131Xe spectrum shows differential line broadening, suggesting the presence of strong adsorption sites. Beyond hp 131Xe NMR spectroscopy studies, a general equation for the high temperature, thermal spin polarization, P, for spin I?1/2 nuclei is presented. PMID:21051249

  12. Effects of carbon ion beam irradiation on the shoot regeneration from in vitro axillary bud explants of the Impatiens hawkeri

    NASA Astrophysics Data System (ADS)

    Zhou, Libin; Zhou, Libin; Li, Wenjian; Li, Ping; Dong, Xicun; Qu, Ying; Ma, Shuang; Li, Qiang

    Accelerated ion beams is an excellent mutagen in plant breeding which can induce higher mutation frequencies and wider mutation spectrum than those of low linear energy transfer (LET) irradiations, such as X-rays (Okamura et al. 2003, Yamaguchi et al. 2003). Mutation breeding operation of two Saintpaulia ionahta cultivars using the method combining plant tissue culture technique and carbon ion beam irradiations were set out at Institute of Modern Physics from 2005 (Zhou et al. 2006). The effects of 960 MeV carbon ion beam and 8 MeV X-ray irradiations on regenerated shoots of Impatiens hawkeri from another kind of explants named in vitro axillary buds explants were studied recently. The biology endpoints in this study included relative number of roots (RNR), relative length of roots (RLR), relative height of shoots (RHS), relative number of nodes (RNN), survival fraction (SF) and morphology changes in the regenerated shoots. The experimental results showed that carbon ion beams inhibited the root and stem developments of axillary bud explants more severely than X-rays did. And the 50% lethal dose (LD50 ) is about 23.3 Gy for the carbon ion beam and 49.1 Gy for the X-rays, respectively. Relative biological effectiveness (RBE) of Impatiens hawkeri with respect to X-rays according to 50% SF was about two. Secondly, the percentage of shoots regenerated with malformed shoots including curliness, carnification, nicks in all Impatiens hawkeri axillary bud explants irradiated with carbon ion beam at 20 Gy accounted for 55.6%, while the highest number for the 40 Gy X-ray irradiation was 40%. Last, many regenerated shoots whose vascular bundle fused together were obtained only from explants irradiated with carbon ion beams. Based on the results above, it can be concluded that the effect of mutation induction by carbon ion beam irradiation on the axillary explants of Impatiens hawkeri is better than that by X-ray irradiation; and the optimal mutagenic dose varies from 20 Gy for carbon ion beam irradiation.

  13. Depth distribution of Frank loop defects formed in ion-irradiated stainless steel and its dependence on Si addition

    NASA Astrophysics Data System (ADS)

    Chen, Dongyue; Murakami, Kenta; Dohi, Kenji; Nishida, Kenji; Soneda, Naoki; Li, Zhengcao; Liu, Li; Sekimura, Naoto

    2015-12-01

    Although heavy ion irradiation is a good tool to simulate neutron irradiation-induced damages in light water reactor, it produces inhomogeneous defect distribution. Such difference in defect distribution brings difficulty in comparing the microstructure evolution and mechanical degradation between neutron and heavy ion irradiation, and thus needs to be understood. Stainless steel is the typical structural material used in reactor core, and could be taken as an example to study the inhomogeneous defect depth distribution in heavy ion irradiation and its influence on the tested irradiation hardening by nano-indentation. In this work, solution annealed stainless steel model alloys are irradiated by 3 MeV Fe2+ ions at 400 °C to 3 dpa to produce Frank loops that are mainly interstitial in nature. The silicon content of the model alloys is also tuned to change point defect diffusion, so that the loop depth distribution influenced by diffusion along the irradiation beam direction could be discussed. Results show that in low Si (0% Si) and base Si (0.42% Si) samples the depth distribution of Frank loop density quite well matches the dpa profile calculated by the SRIM code, but in high Si sample (0.95% Si), the loop number density in the near-surface region is very low. One possible explanation could be Si's role in enhancing the effective vacancy diffusivity, promoting recombination and thus suppressing interstitial Frank loops, especially in the near-surface region, where vacancies concentrate. By considering the loop depth distribution, the tested irradiation hardening is successfully explained by the Orowan model. A hardening coefficient of around 0.30 is obtained for all the three samples. This attempt in interpreting hardening results may make it easier to compare the mechanical degradation between different irradiation experiments.

  14. Ion irradiation of Fe-Fe oxide core-shell nanocluster films: Effect of interface on stability of magnetic properties

    SciTech Connect

    McCloy, John S.; Jiang, Weilin; Droubay, Timothy C.; Varga, Tamas; Kovarik, Libor; Sundararajan, Jennifer A.; Kaur, Maninder; Qiang, You; Burks, Edward C.; Liu, Kai

    2013-08-28

    A cluster deposition method was used to produce films of loosely aggregated nanoclusters (NCs) of Fe core-Fe{sub 3}O{sub 4} shell or fully oxidized Fe{sub 3}O{sub 4}. Films of these NC on Si(100) or MgO(100)/Fe{sub 3}O{sub 4}(100) were irradiated to 10{sup 16} Si{sup 2+}/cm{sup 2} near room temperature using an ion accelerator. Ion irradiation creates structural change in the NC film with corresponding chemical and magnetic changes which depend on the initial oxidation state of the cluster. Films were characterized using magnetometry (hysteresis, first order reversal curves), microscopy (transmission electron, helium ion), and x-ray diffraction. In all cases, the particle sizes increased due to ion irradiation, and when a core of Fe is present, irradiation reduces the oxide shells to lower valent Fe species. These results show that ion irradiated behavior of the NC films depends strongly on the initial nanostructure and chemistry, but in general saturation magnetization decreases slightly.

  15. Formation of XeI(B) in low pressure inductive radio frequency electric discharges sustained in mixtures of Xe and I2

    NASA Astrophysics Data System (ADS)

    Barnes, Paul N.; Kushner, Mark J.

    1996-11-01

    Low pressure excimer discharges (<1-5 Torr) are of interest for use as ultraviolet sources for lighting applications. XeI(B) is an attractive candidate for excimer lamps due to the low corrosive properties of iodine. The excimer is thought to be formed by either harpoon or ion-ion recombination reactions, the latter of which requires a third body. The formation of the excimer at low pressures is therefore problematic. To address this issue, an investigation was conducted to determine the kinetic processes which produce XeI(B) in a low pressure (0.5-5 Torr) inductive radio frequency discharge sustained in Xe and I2. The diagnostics applied in this study include laser-induced fluorescence, optical absorption spectroscopy, and optical emission spectroscopy. Our results indicate that for the experimental conditions, Xe+I2**?XeI(B)+I is a major reaction producing the excimer. This result differs from studies performed at higher pressures which concluded that the harpoon reaction between Xe* and I2 or ionic recombination between Xe+2 and I- are the major sources of XeI(B).

  16. Correlation between structure and electrical transport in ion-irradiated graphene grown on Cu foils

    SciTech Connect

    Buchowicz, G.; Stone, P.R.; Robinson, J.T.; Cress, C.D.; Beeman, J.W.; Dubon, O.D.

    2010-11-04

    Graphene grown by chemical vapor deposition and supported on SiO2 and sapphire substrates was studied following controlled introduction of defects induced by 35 keV carbon ion irradiation. Changes in Raman spectra following fluences ranging from 1012 cm-2 to 1015 cm-2 indicate that the structure of graphene evolves from a highly-ordered layer, to a patchwork of disordered domains, to an essentially amorphous film. These structural changes result in a dramatic decrease in the Hall mobility by orders of magnitude while, remarkably, the Hall concentration remains almost unchanged, suggesting that the Fermi level is pinned at a hole concentration near 1x1013 cm-2. A model for scattering by resonant scatterers is in good agreement with mobility measurements up to an ion fluence of 1x1014 cm-2.

  17. Ion beam induced luminescence analysis of defect evolution in lithium fluoride under proton irradiation

    NASA Astrophysics Data System (ADS)

    Quaranta, A.; Valotto, G.; Piccinini, M.; Montereali, R. M.

    2015-11-01

    Ion beam induced luminescence (IBIL) spectra of pure LiF under irradiation by a 2 MeV proton beam were analyzed as a function of the dose in order to deepen the kinetic mechanisms underlying the formation of luminescent point defects. The intensity evolution with dose at several emission wavelengths has been studied within a wide spectral interval, from ultraviolet (UV) to near infrared (NIR), and their different change rates have been correlated to the electronic defect formation processes. The intensity at few selected wavelengths was analyzed with a multiple linear regression (MLR) method in order to demonstrate that a linear calibration curve can be obtained and that an on-line optical dose monitor for ion beams can be realized.

  18. SAXS Analysis of Embedded Pt Nanocrystals Irradiated with Swift Heavy Ions

    SciTech Connect

    Giulian, R.; Kluth, P.; Sprouster, D. J.; Araujo, L. L.; Byrne, A. P.; Ridgway, M. C.; Cookson, D. J.

    2009-01-29

    Elongated Pt nanocrystals (NCs) formed in SiO{sub 2} by ion implantation, thermal annealing and swift heavy ion irradiation were analyzed by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) measurements. Transmission SAXS measurements were performed in samples aligned at different angles relative to the photon beam resulting in non-isotropic scattering and thus enabling the three dimensional analysis of the NCs. Selected angular sectors of the detector were integrated and analyzed separately, leading to the individual evaluation of both the major and minor dimensions of the rod-shaped NCs. This method enables the use of well established spherical models for the SAXS data analysis and yielded excellent agreement with TEM results.

  19. Long term study of the effectiveness of in-situ chemical source clean with XeF2 on ion implanter

    NASA Astrophysics Data System (ADS)

    Fuchs, Dieter; Kerkel, Klaus; Vogl, Josef; Dorozynskyj, Michael

    2012-11-01

    In the last few years the results of the in-situ chemical clean of ion sources were presented for different tool types. All evaluations show a significant improvement of the source life time. Furthermore reduced assists, glitches and tuning failures were observed. The results are mainly based on the use of the common species mixture of boron, arsenic and phosphorous. We will discuss long term behavior of in-situ clean usage on Axcelis GSD tools and the influence of the applied species mixture.

  20. Ion-beam induced magnetic anisotropies in iron films

    NASA Astrophysics Data System (ADS)

    Neubauer, M.; Reinecke, N.; Uhrmacher, M.; Lieb, K. P.; Münzenberg, M.; Felsch, W.

    1998-04-01

    100-300 nm thin Fe layers evaporated onto crystalline and amorphous Si or SiO 2 substrates were irradiated, at 77 K, with 10 14-10 16 Xe +-ions/cm 2 at 450 keV beam energy. The magnetizations in the films were measured by means of Perturbed Angular Correlation (PAC) spectroscopy with implanted 111In tracer ions, or the Magneto-Optic Kerr Effect (MOKE). Upon ion implantation, dramatic changes of the magnetic anisotropy were observed which are attributed to ion-beam enhanced lateral grain growth. Very little influence of the deposition parameters (type and cristallinity of substrate, evaporation rate) on the anisotropic magnetization was found.

  1. Antiradiation Vaccine: Technology Development- Radiation Tolerance,Prophylaxis, Prevention And Treatment Of Clinical Presentation After Heavy Ion Irradiation.

    NASA Astrophysics Data System (ADS)

    Popov, Dmitri; Maliev, Slava; Jones, Jeffrey

    Introduction: Research in the field of biological effects of heavy charged particles is necessary for both heavy-ion therapy (hadrontherapy) and protection from the exposure to galactic cosmic radiation in long-term manned space missions.[Durante M. 2004] In future crew of long-term manned missions could operate in exremely high hadronic radiation areas of space and will not survive without effective radiation protection. An Antiradiation Vaccine (AV) must be an important part of a countermeasures regimen for efficient radiation protection purposes of austronauts-cosmonauts-taukonauts: immune-prophylaxis and immune-therapy of acute radiation toxic syndromes developed after heavy ion irradiation. New technology developed (AV) for the purposes of radiological protection and improvement of radiation tolerance and it is quite important to create protective immune active status which prevent toxic reactions inside a human body irradiated by high energy hadrons.[Maliev V. et al. 2006, Popov D. et al.2008]. High energy hadrons produce a variety of secondary particles which play an important role in the energy deposition process, and characterise their radiation qualities [Sato T. et al. 2003] Antiradiation Vaccine with specific immune-prophylaxis by an anti-radiation vaccine should be an important part of medical management for long term space missions. Methods and experiments: 1. Antiradiation vaccine preparation standard, mixture of toxoid form of Radiation Toxins [SRD-group] which include Cerebrovascular RT Neurotoxin, Cardiovascular RT Neurotoxin, Gastrointestinal RT Neurotoxin, Hematopoietic RT Hematotoxin. Radiation Toxins of Radiation Determinant Group isolated from the central lymph of gamma-irradiated animals with Cerebrovascular, Cardiovascular, Gastro-intestinal, Hematopoietic forms of ARS. Devices for radiation are "Panorama", "Puma". 2. Heavy ion exposure was accomplished at Department of Research Institute of Nuclear Physics, Dubna, Russia. The heavy ions irradiation was generated in heavy ion (Fe56) accelerator - UTI. Heavy Ion linear transfer energy - 2000- 2600 KeV -mkm, 600 MeV -92U. Absorbed Dose - 3820 Rad. Experimental Design: Rabbits from all groups were irradiated by heavy ion accelerator. Group A: control-10 rabbits; Group B: placebo-5 rabbits; Group C: Radioprotectant Cystamine (50 mg-kg)-5 rabbits, 15 minutes before irradiation - 5 rabbits; Group D: Radioprotectant Gammafos (Amifostine 400mg -kg ) - 5 rabbits; Group E: Antiradiation Vaccine: subcutaneus administration or IM - 2 ml of active substance, 14 days before irradiation Results: Group A 100% mortality within two hours after heavy ion irradiation with clinical symptoms of Acute Cerebro- and Cardio-Vascular Radiation syndromes. Group B 100% mortality within 15 hours following irradiation. Group C 100% mortality within 14-15 hours after irradiation. Group D 100% mortality within 15-16 hours after irradiation. In groups A- D registered the development of acute radiation cerebrovascular and cardiovascular syndromes and also extensive burns. of skin produced rapid death. Group E -100% mortality in 280-290 hours (12 days) following heavy ion irradiation with animals exhibiting a combination or individual forms of Acute Cerebrovascular, Cardiovascular, and Gastrointestinal forms and focal skin burns. Discussion Antiradiation vaccine and immune-prophylaxis is an effective method of neutralization of Radiation Toxins. Vaccination before irradiation extended survival time after irradiation with heavy ions from two hours up to 300 hours. Clinical signs, clinical features, symptoms were somewhat attenuated. Degree of clinical forms of Acute Radiation Syndromes were diminished in their clinical manifestation and severity. Groups A-D demonstrated extremely severe level of Cerebrovascular and Cardiovascular forms of Acute Radiation Syndromes and lethality 100% was registered in short time after irradiation. Radiation induced burns in this groups (with Cutaneous sub-syndrome of ARS - Degree 4, that diffuse deep into soft tissues with extensi

  2. Xe-implanted zirconium oxycarbide studied by variable energy positron beam

    NASA Astrophysics Data System (ADS)

    Djourelov, N.; Gutierrez, G.; Marinov, H.; Popov, E.; Toulhoat, N.; Moncoffre, N.; Pipon, Y.; Nédélec, P.

    2011-12-01

    The effect of annealing on defects and the formation of Xe bubbles were investigated in zirconium oxycarbide implanted with 800-keV 136Xe 2+ ions at two fluences 1 × 10 15 and 1 × 10 16 Xe/cm 2. Doppler broadening technique combined with slow positron beam was used. The analysis of the S depth profiles and S- W maps revealed that in the as-implanted samples at both fluences Xe bubbles are not formed. The post-implantation annealing of the samples implanted at 1 × 10 16 Xe/cm 2 caused formation of Xe bubbles. The response of the lower implantation dose samples to this post implantation annealing was found rather complicated and is discussed.

  3. Temperature dependent surface modification of molybdenum due to low energy He+ ion irradiation

    NASA Astrophysics Data System (ADS)

    Tripathi, J. K.; Novakowski, T. J.; Joseph, G.; Linke, J.; Hassanein, A.

    2015-09-01

    In this paper, we report on the temperature dependent surface modifications in molybdenum (Mo) samples due to 100 eV He+ ion irradiation in extreme conditions as a potential candidate to plasma-facing components in fusion devices alternative to tungsten. The Mo samples were irradiated at normal incidence, using an ion fluence of 2.6 × 1024 ions m-2 (with a flux of 7.2 × 1020 ions m-2 s-1). Surface modifications have been studied using high-resolution field emission scanning electron-(SEM) and atomic force (AFM) microscopy. At 773 K target temperature homogeneous evolution of molybdenum nanograins on the entire Mo surface were observed. However, at 823 K target temperature appearance of nano-pores and pin-holes nearby the grain boundaries, and Mo fuzz in patches were observed. The fuzz density increases significantly with target temperatures and continued until 973 K. However, at target temperatures beyond 973 K, counterintuitively, a sequential reduction in the fuzz density has been seen till 1073 K temperatures. At 1173 K and above temperatures, only molybdenum nano structures were observed. Our temperature dependent studies confirm a clear temperature widow, 823-1073 K, for Mo fuzz formation. Ex-situ high resolution X-ray photoelectron spectroscopy studies on Mo fuzzy samples show the evidence of MoO3 3d doublets. This elucidates that almost all the Mo fuzz were oxidized during open air exposure and are thick enough as well. Likewise the microscopy studies, the optical reflectivity measurements also show a sequential reduction in the reflectivity values (i.e., enhancement in the fuzz density) up to 973 K and after then a sequential enhancement in the reflectivity values (i.e., reduction in the fuzz density) with target temperatures. This is in well agreement with microscopy studies where we observed clear temperature window for Mo fuzz growth.

  4. Heavy-ion irradiation defect accumulation in ZrN characterized by TEM, GIXRD, nanoindentation, and helium desorption

    NASA Astrophysics Data System (ADS)

    Egeland, G. W.; Valdez, J. A.; Maloy, S. A.; McClellan, K. J.; Sickafus, K. E.; Bond, G. M.

    2013-04-01

    A study on zirconium nitride was performed to assess the effect of radiation damage by heavy ions at cryogenic and elevated temperatures. Cross-sectional transmission electron microscopy, grazing incidence X-ray diffraction, nanoindentation, and helium desorption studies were used to assess the damage and its effects. Xenon and krypton were used as heavy ions at 300 keV to displacement damage as high as 200 dpa. Implants were cryogenic, 350 °C, 580 °C, and 800 °C. Amorphization was not observed at low temperatures nor was bubble formation observed at elevated temperatures, however, defect migration was observed at elevated temperatures. Nanoindenter results showed the onset of defect saturation. Helium release studies were performed to show the effect of increasing damage by Xe to 40 dpa.

  5. Gamma irradiation-induced modifications of polymers found in nuclear waste embedding processes Part II: The ion-exchange resin

    NASA Astrophysics Data System (ADS)

    Debré, O.; Nsouli, B.; Thomas, J.-P.; Stevenson, I.; Colombini, D.; Romero, M.-A.

    1997-08-01

    Ion exchange resins (IERs) saturated in cesium and borate ions are well representative of low and medium activity nuclear waste to be embedded in an epoxy resin/amine hardener, such a conditioning procedure being under qualification. In order to test these materials in realistic conditions they are externally irradiated (air and water), in mixed beds saturated in fixed ions (cesium and borate) and water. Irradiation effects are evidenced with the HSF-SIMS technique by the variation of the emission characteristic of both the fixed ions, the chemical structure of the IERs and their interrelationship, both from the analysis of the solid material and of the residual or rinsing water. It appears that the fixed ions can be released in surrounding water as a consequence of radiation-induced resin fragments solubility.

  6. Structural Evolution of Fe Particles in Fe-Al2O3 Granular Films by Ar Ion Irradiations

    NASA Astrophysics Data System (ADS)

    Nakayama, Hiro; Ishida, Tomoya; Kinoshita, Ryosuke; Purwanto, Setyo; Sakamoto, Isao; Honda, Shigeo; Koike, Masaki; Yasumoto, Masato; Hayashi, Nobuyuki; Toriyama, Tamotsu

    2013-01-01

    Fe-Al2O3 granular films were prepared by helicon plasma sputtering. Fe64(Al2O3)36 in volume percent of as-prepared films was irradiated with 400 keV Ar ions in the fluence range of 1×1015-5×1016 ions/cm2. The growth of Fe particles with increasing ion fluence was observed from X-ray diffraction (XRD) patterns, magnetization curves, and conversion electron Mössbauer (CEM) spectra. The magnetization curves and CEM spectra of as-prepared Fe-Al2O3 films indicated the superparamagnetic nature and the ferromagnetic nature with increasing ion fluence. In addition, the reduction of Fe3+ component to the Fe2+ and metallic Fe components by ion irradiation was observed from CEM spectra.

  7. Channel waveguide lasers at 1064??nm in Nd:YAG crystal produced by C?? ion irradiation with shadow masking.

    PubMed

    Yao, Yicun; Jia, Yuechen; Chen, Feng; Akhmadaliev, Shavkat; Zhou, Shengqiang

    2014-01-10

    We report on the fabrication of channel waveguides in Nd:YAG crystals, using swift C?? ion irradiation with ion energy of 15 MeV and fluence at 5×10¹? ions/cm². A laser-cut shadow mask of a number of open stripes with varied width was covered on the sample surface during the ion irradiation. Channel waveguides were formed in the Nd:YAG crystal due to the refractive index increase along the ion trajectory. Room temperature waveguide laser oscillations at 1064 nm have been observed under 808 nm optical pumping, with laser slope efficiency at 38% and a maximum output power of 36 mW. PMID:24514049

  8. Evolution and tailoring of plasmonic properties in Ag:ZrO{sub 2} nanocomposite films by swift heavy ion irradiation

    SciTech Connect

    Kumar, Manish; Kulriya, P. K.; Avasthi, D. K.; Pivin, J. C.

    2011-02-15

    Ag:ZrO{sub 2} nanocomposite films have been synthesized by a sol-gel dip coating process at room temperature, followed by irradiation using swift heavy ions. The effect of electronic energy loss and fluences on the evolution and consequently on the tailoring of plasmonic properties of films has been studied. The optical study exhibits that color of films converts from transparent in pristine form into shiny yellow when films are irradiated by 100 MeV Ag ions at a fluence of 3x10{sup 12} ions/cm{sup 2}. However, irradiation by 120 MeV O ions up to the fluence of 1 x 10{sup 14} ions/cm{sup 2} does not induce any coloration in films. The coloration is attributed to the evolution of plasmonic feature resulting in a surface plasmon resonance (SPR) induced absorption peak in the visible region. Increase in fluence from 3 x 10{sup 12} to 6 x 10{sup 13} ions/cm{sup 2} of 100 MeV Ag ions induces a redshift in SPR induced peak position from 434 to 487 nm. Microstructural studies confirms the conversion of Ag{sub 2}O{sub 3} (in pristine films) into cubic phase of metallic Ag and the increase of average size of particles with the increasing fluence up to 6 x 10{sup 13} ions/cm{sup 2}. Further increase in fluence leads to the dissolution of Ag atoms in the ZrO{sub 2} matrix.

  9. Evolution and tailoring of plasmonic properties in Ag:ZrO2 nanocomposite films by swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Kumar, Manish; Kulriya, P. K.; Pivin, J. C.; Avasthi, D. K.

    2011-02-01

    Ag:ZrO2 nanocomposite films have been synthesized by a sol-gel dip coating process at room temperature, followed by irradiation using swift heavy ions. The effect of electronic energy loss and fluences on the evolution and consequently on the tailoring of plasmonic properties of films has been studied. The optical study exhibits that color of films converts from transparent in pristine form into shiny yellow when films are irradiated by 100 MeV Ag ions at a fluence of 3×1012 ions/cm2. However, irradiation by 120 MeV O ions up to the fluence of 1 × 1014 ions/cm2 does not induce any coloration in films. The coloration is attributed to the evolution of plasmonic feature resulting in a surface plasmon resonance (SPR) induced absorption peak in the visible region. Increase in fluence from 3 × 1012 to 6 × 1013 ions/cm2 of 100 MeV Ag ions induces a redshift in SPR induced peak position from 434 to 487 nm. Microstructural studies confirms the conversion of Ag2O3 (in pristine films) into cubic phase of metallic Ag and the increase of average size of particles with the increasing fluence up to 6 × 1013 ions/cm2. Further increase in fluence leads to the dissolution of Ag atoms in the ZrO2 matrix.

  10. Radiosensitizing effect of gold nanoparticles in carbon ion irradiation of human cervical cancer cells

    SciTech Connect

    Kaur, Harminder; Avasthi, D. K.; Pujari, Geetanjali; Sarma, Asitikantha

    2013-07-18

    Noble metal nanoparticles have received considerable attention in biotechnology for their role in bio sensing due to surface plasmon resonance, medical diagnostics due to better imaging contrast and therapy. The radiosensitization effect of gold nanoparticles (AuNP) has been gaining popularity in radiation therapy of cancer cells. The better depth dose profile of energetic ion beam proves its superiority over gamma radiation for fighting against cancer. In the present work, the glucose capped gold nanoparticles (Glu-AuNP) were synthesised and internalized in the HeLa cells. Transmission electron microscopic analysis of ultrathin sections of Glu-AuNP treated HeLa cells confirmed the internalization of Glu-AuNPs. Control HeLa cells and Glu-AuNp treated HeLa cells were irradiated at different doses of 62 MeV 12C ion beam (LET - 290keV/{mu}m) at BIO beam line of using 15UD Pelletron accelerator at Inter University Accelerator Centre, New Delhi, India. The survival fraction was assessed by colony forming assay which revealed that the dose of carbon ion for 90% cell killing in Glu-AuNP treated HeLa cells and control HeLa cells are 2.3 and 3.2 Gy respectively. This observation shows {approx} 28% reduction of {sup 12}C{sup 6+} ion dose for Glu-AuNP treated HeLa cells as compared to control HeLa cells.

  11. Single-cell/Single-particle Irradiation Using Heavy-ion Microbeams

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yasuhiko

    Heavy charged particles transfer their energy to biological organisms through high-density ionization along the particle trajectories. The population of cells exposed to a very low dose of heavy-ion beams contains a few cells hit by a particle, while the majority of the cells receive no radiation damage. At somewhat higher doses, some of the cells receive two or more events according to the Poisson distribution of ion injections. This fluctuation of particle trajectories through individual cells makes interpretation of radiological effects of heavy ions difficult. Furthermore, there has recently been an increasing interest in ionizing radiation-induced “bystander effects”, that is, radiation effects transmitted from hit cells to neighboring un-hit cells. Therefore, we have established a single-cell/single-particle irradiation system using a heavy-ion microbeam apparatus at JAEA-Takasaki to study radiobiological processes in hit cells and bystander cells exposed to low dose and low dose-rate high-LET radiations, in ways that cannot be achieved using conventional broad-field exposures.

  12. Ion heating dynamics in solid buried layer targets irradiated by ultra-short intense laser pulses

    SciTech Connect

    Huang, L. G.; Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden; University of Chinese Academy of Sciences, 100049 Beijing ; Bussmann, M.; Kluge, T.; Lei, A. L.; Yu, W.; Cowan, T. E.; Technische Universität Dresden, 01062 Dresden

    2013-09-15

    We investigate bulk ion heating in solid buried layer targets irradiated by ultra-short laser pulses of relativistic intensities using particle-in-cell simulations. Our study focuses on a CD{sub 2}-Al-CD{sub 2} sandwich target geometry. We find enhanced deuteron ion heating in a layer compressed by the expanding aluminium layer. A pressure gradient created at the Al-CD{sub 2} interface pushes this layer of deuteron ions towards the outer regions of the target. During its passage through the target, deuteron ions are constantly injected into this layer. Our simulations suggest that the directed collective outward motion of the layer is converted into thermal motion inside the layer, leading to deuteron temperatures higher than those found in the rest of the target. This enhanced heating can already be observed at laser pulse durations as low as 100 fs. Thus, detailed experimental surveys at repetition rates of several ten laser shots per minute are in reach at current high-power laser systems, which would allow for probing and optimizing the heating dynamics.

  13. Time-resolved electron kinetics in swift heavy ion irradiated solids

    NASA Astrophysics Data System (ADS)

    Medvedev, N. A.; Rymzhanov, R. A.; Volkov, A. E.

    2015-09-01

    The event-by-event Monte Carlo model, TREKIS, was developed to describe the excitation of the electron subsystems of various solids by a penetrating swift heavy ion (SHI), the spatial spreading of generated fast electrons, and secondary electron and hole cascades. Complex dielectric function formalism is used to obtain relevant cross sections. This allows the recognition of fundamental effects resulting from the collective response of the electron subsystem of a target for excitation that is not possible within the binary collision approximation of these cross sections, e.g. the differences in the electronic stopping of an ion and in the electron mean free paths for different structures (phases) of a material. A systematic study performed with this model for different materials (insulators, semiconductors and metals) revealed effects which may be important for an ion track: e.g. the appearance of a second front of excess electronic energy propagation outwards from the track core following the primary front of spreading of generated electrons. We also analyze how the initial ballistic spatial spreading of fast electrons generated in a track turns to the diffusion ~10 fs after ion passage. Detailed time-resolved simulations of electronic subsystem kinetics helped in understanding the reasons behind enhanced silicon resistance to SHI irradiation in contrast to easily produced damage in this material by femtosecond laser pulses. We demonstrate that the fast spreading of excited electrons from the track core on a sub-100 fs timescale prevents the Si lattice from nonthermal melting in a relaxing SHI track.

  14. Relief evolution of HOPG under high-fluence 30 keV argon ion irradiation

    NASA Astrophysics Data System (ADS)

    Andrianova, N. N.; Borisov, A. M.; Mashkova, E. S.; Shemukhin, A. A.; Shulga, V. I.; Virgiliev, Yu. S.

    2015-07-01

    The results of the experimental study of sputtering and erosion of the basal plane of HOPG under irradiation with 30-keV Ar+ in the range from RT to 400 °C are presented. It has been found that developed at elevated (?250 °C) temperatures needle-like microscopic relief results in twofold sputtering yield increase (Y ? 2) in comparison with sputtering of a surface with an etch pits microscopic relief at the temperatures less than the ion-induced texture transition temperature Tt ? 150 °C. The effects of ion-induced graphite relief on high-dose sputtering have been studied using binary-collision computer simulation. The relief was modeled as a sine function surface along two mutually perpendicular surface axes. The simulation has shown that at some parameters of the relief the essential part of the bombarding ions undergoes inclined incidence on the walls of surface hillocks, which increases the density of ion-atom collisions near the surface and, correspondingly, the ejection of atoms. This effect leads to non-monotonic behavior of the sputtering yield on the relief aspect ratio (amplitude/period). The sputtering yield decreases upon reaching the maximum at aspect ratio of 4, and becomes lower than that for a flat surface. The simulation permits to estimate the relation of amplitude to period of relief at T < Tt.

  15. Synthesis of silver and copper nanoparticle containing a-C:Hby ion irradiation of polymers

    NASA Astrophysics Data System (ADS)

    Schwarz, F.; Thorwarth, G.; Stritzker, B.

    2009-10-01

    One of the many applications of diamond like carbon (DLC) is the biocompatible coating of medical tools and implants. The most recent field of interest concerns the generation of antimicrobial activity in combination with the excellent wear resistance and biocompatibility of DLC. As has already been shown for polymers, nanoparticles of silver or copper within a carbonacious matrix have a bactericidal effect. In this work we describe a new technique to produce amorphous hydrogenated carbon films (a-C:H), which contain nanometer sized clusters of silver or copper. The hybrid deposition process is based on sol-gel synthesis of polymer films and subsequent ion-induced densification and cross-linking to form a-C:H. By thermal or UV-induced reduction of metal salts in polymer solution, colloidal metal particles are produced. In this way polymer films, already containing noble metal nanoclusters, can be deposited in a wet chemical step. Upon sol-gel deposition, the polymer is subjected to ion irradiation. Based on earlier results, the influence of ion energy on chemical and mechanical properties, as well as bonding structure is investigated. Special attention is also dedicated to ion-induced diffusion and growth as well as oxidation effects.

  16. Radiosensitizing effect of gold nanoparticles in carbon ion irradiation of human cervical cancer cells

    NASA Astrophysics Data System (ADS)

    Kaur, Harminder; Avasthi, D. K.; Pujari, Geetanjali; Sarma, Asitikantha

    2013-07-01

    Noble metal nanoparticles have received considerable attention in biotechnology for their role in bio sensing due to surface plasmon resonance, medical diagnostics due to better imaging contrast and therapy. The radiosensitization effect of gold nanoparticles (AuNP) has been gaining popularity in radiation therapy of cancer cells. The better depth dose profile of energetic ion beam proves its superiority over gamma radiation for fighting against cancer. In the present work, the glucose capped gold nanoparticles (Glu-AuNP) were synthesised and internalized in the HeLa cells. Transmission electron microscopic analysis of ultrathin sections of Glu-AuNP treated HeLa cells confirmed the internalization of Glu-AuNPs. Control HeLa cells and Glu-AuNp treated HeLa cells were irradiated at different doses of 62 MeV 12C ion beam (LET - 290keV/?m) at BIO beam line of using 15UD Pelletron accelerator at Inter University Accelerator Centre, New Delhi, India. The survival fraction was assessed by colony forming assay which revealed that the dose of carbon ion for 90% cell killing in Glu-AuNP treated HeLa cells and control HeLa cells are 2.3 and 3.2 Gy respectively. This observation shows ˜ 28% reduction of 12C6+ ion dose for Glu-AuNP treated HeLa cells as compared to control HeLa cells.

  17. Formation of multilayered magnetic nanotracks with perpendicular anisotropy via deoxidization using ion irradiation on ultraviolet-imprinted intaglio nanostructures

    SciTech Connect

    Cho, Eikhyun; Shin, Sang Chul; Han, Jungjin; Shim, Jongmyeong; Shin, Ryung; Kang, Shinill; Kim, Sanghoon; Hong, Jongill

    2015-01-26

    We proposed a method to fabricate perpendicular magnetic nanotracks in the cobalt oxide/palladium multilayer films using UV-nanoimprinting lithography and low-energy hydrogen-ion irradiation. This is a method to magnetize UV-imprinted intaglio nanotracks via low-energy hydrogen ion irradiation, resulting the irradiated region are magnetically separated from the non-irradiated region. Multilayered magnetic nanotracks with a line width of 140?nm, which were fabricated by this parallel process without additional dry etching process, exhibited a saturation magnetization of 290?emu?cm{sup ?3} and a coercivity of 2 kOe. This study demonstrates a cost-effective mass production of multilayered perpendicular magnetic nanotracks and offers the possibility to achieve high density storage and memory devices.

  18. Resistance of (Fe, Ni)/sub 3/V long-range-ordered alloys to neutron and ion irradiation

    SciTech Connect

    Braski, D.N.

    1981-01-01

    A series of (Fe, Ni)/sub 3/V long-range-ordered alloys were irradiated with neutrons in the Oak Ridge Research Reactor (ORR) and with 4 MeV Ni ions at temperatures above 250/sup 0/C. The displacement damage levels for the two irradiations were 3.8 and 70 dpa, and the helium levels were 29 and 560 at. ppM, respectively. Irradiation in ORR generally increased the yield strength and lowered the ductility of an LRO alloy, but produced relatively little swelling. The LRO alloys retained their long-range order after ion irradiation below the critical ordering temperature, T/sub c/, and exhibited low swelling. Above T/sub c/ the alloys were disordered and showed greater swelling. Adjustment of alloy composition to prevent sigma phase formation reduced swelling.

  19. Electrical and magnetic properties modification in heavy ion irradiated nanograin NixCo(3-x)O4 films

    SciTech Connect

    Mccloy, John S.; Jiang, Weilin; Bennett, Wendy D.; Engelhard, Mark H.; Lindemuth, Jeffrey; Parmar, Narendra S.; Exarhos, Gregory J.

    2015-09-10

    Reactively sputtered NixCo(3-x)O4 films (x = 1.5, 1.0, and 0.75) were grown and subsequently irradiated with 5.5 MeV Si+ ions to investigate effects of lattice-site and charge state distribution. Films were characterized before and after irradiation by x-ray diffraction, x-ray photoemission spectroscopy, Rutherford backscattering spectroscopy, electric resistivity measurements, and temperature-dependent AC and DC magnetometry. Results indicate that ion irradiation induces oxygen loss, partial reduction of nickel, and an increase in both low temperature ferrimagnetism and room temperature conductivity. Frequency dependent AC magnetic susceptibility measurements indicate a spin-glass like transition at low temperature which moves to higher temperature after irradiation. Significance of the charge transfer for magnetism and conduction in a mixed spinel with Co2+, Co3+, Ni2+, and Ni3+ in tetrahedral and octahedral sites is discussed.

  20. Carbon Ion Irradiated Neural Injury Induced the Peripheral Immune Effects in Vitro or in Vivo

    PubMed Central

    Lei, Runhong; Zhao, Tuo; Li, Qiang; Wang, Xiao; Ma, Hong; Deng, Yulin

    2015-01-01

    Carbon ion radiation is a promising treatment for brain cancer; however, the immune system involved long-term systemic effects evoke a concern of complementary and alternative therapies in clinical treatment. To clarify radiotherapy caused fundamental changes in peripheral immune system, examinations were performed based on established models in vitro and in vivo. We found that brain-localized carbon ion radiation of neural cells induced complex changes in the peripheral blood, thymus, and spleen at one, two, and three months after its application. Atrophy, apoptosis, and abnormal T-cell distributions were observed in rats receiving a single high dose of radiation. Radiation downregulated the expression of proteins involved in T-cell development at the transcriptional level and increased the proportion of CD3+CD4?CD8+ T-cells in the thymus and the proportion of CD3+CD4+CD8? T-cells in the spleen. These data show that brain irradiation severely affects the peripheral immune system, even at relatively long times after irradiation. In addition, they provide valuable information that will implement the design of biological-based strategies that will aid brain cancer patients suffering from the long-term side effects of radiation. PMID:26633364

  1. Carbon Ion Irradiated Neural Injury Induced the Peripheral Immune Effects in Vitro or in Vivo.

    PubMed

    Lei, Runhong; Zhao, Tuo; Li, Qiang; Wang, Xiao; Ma, Hong; Deng, Yulin

    2015-01-01

    Carbon ion radiation is a promising treatment for brain cancer; however, the immune system involved long-term systemic effects evoke a concern of complementary and alternative therapies in clinical treatment. To clarify radiotherapy caused fundamental changes in peripheral immune system, examinations were performed based on established models in vitro and in vivo. We found that brain-localized carbon ion radiation of neural cells induced complex changes in the peripheral blood, thymus, and spleen at one, two, and three months after its application. Atrophy, apoptosis, and abnormal T-cell distributions were observed in rats receiving a single high dose of radiation. Radiation downregulated the expression of proteins involved in T-cell development at the transcriptional level and increased the proportion of CD3?CD4(-)CD8? T-cells in the thymus and the proportion of CD3?CD4?CD8(-) T-cells in the spleen. These data show that brain irradiation severely affects the peripheral immune system, even at relatively long times after irradiation. In addition, they provide valuable information that will implement the design of biological-based strategies that will aid brain cancer patients suffering from the long-term side effects of radiation. PMID:26633364

  2. Mechanisms of nanodot formation under focused ion beam irradiation in compound semiconductors

    SciTech Connect

    Grossklaus, K. A.; Millunchick, J. M.

    2011-01-01

    We have examined the responses of GaAs, InP, InAs, and AlAs to 30 keV focused ion beam (FIB) irradiation and applied a unified model that consistently explains the observed effects. Nanodots were observed to form on GaAs, InP, and InAs under irradiation at normal incidence, while nanodots are not observed on AlAs. The FIB response and nanodot formation behavior of each material is discussed with regard to a few basic material properties and a model for nanodot creation and growth by the action of preferential sputtering and Ostwald ripening. The model predicts the development of a stable average nanodot size with increasing ion dose, with the average nanodot size depending on the excess group III adatom yield, adatom surface diffusion rate, and surface tension. These predictions qualitatively agree with the experimentally observed trends for GaAs and InP. They also agree for the initial nanodot formation on InAs, but this material system exhibits a sudden transition in the nanodot size distribution. The model predicts that nanodots will have difficulty forming and growing on AlAs, which is also in agreement with our experimental results.

  3. Dynamics of photogenerated nonequilibrium electronic states in Ar+-ion-irradiated SrTiO3

    NASA Astrophysics Data System (ADS)

    Kumar, Dushyant; Hossain, Z.; Budhani, R. C.

    2015-05-01

    A metallic surface is realized on stoichiometric and insulating (100) SrTiO3 by Ar+-ion irradiation. The sheet carrier density and Hall mobility of the layer are ˜4.0 ×1014cm-2 and ˜2 ×103cm2/Vs , respectively, at 15 K for the irradiation dose of ˜4.2 ×1018ions/cm2 . These samples display ultraviolet light sensitive photoconductivity (PC) which is enhanced abruptly below the temperature (?100 K) where SrTiO3 crystal undergoes an antiferrodistortive cubic-to-tetragonal (Oh1?D4h 18 ) structural phase transition. This behavior of PC maps well with the temperature dependence of dielectric function and electric field induced conductivity. The longevity of the PC state also shows a distinct change below ?100 K. At T >100 K its decay is thermally activated with an energy barrier of ?36 meV, whereas at T <100 K it becomes independent of temperature. We have examined the effect of electrostatic gating on the lifetime of the PC state. One nontrivial result is the ambient temperature quenching of the photoconducting state by the negative gate field. This observation opens avenues for designing a solid state photoelectric switch. The origin and lifetime of the PC state are understood in the light of field effect induced band bending, defect dynamics, and thermal relaxation processes.

  4. Adhesive hydrophobicity of Cu2O nano-columnar arrays induced by nitrogen ion irradiation.

    PubMed

    Dhal, Satyanarayan; Chatterjee, Sriparna; Manju, Unnikrishnan; Tribedi, Lokesh C; Thulasiram, K V; Fernandez, W A; Chatterjee, Shyamal

    2015-11-25

    Low energy nitrogen ions are used in this work to manipulate wetting properties of the surface of the array of Cu2O nano-columns, which yields remarkable results. The nano-columnar thin films were grown on a highly conductive silicon surface by a sputter deposition technique. The films were irradiated at two different fluences of 5 × 10(15) and 1 × 10(16) ions per cm(2), respectively. With increasing fluence the shape of column tip changes, columns are bent and porous channels between columns are clogged up. While the surface of the pristine sample is hydrophilic, the irradiated surface turns into hydrophobic but having adhesion properties. We have analysed the structural and chemical properties of the surface in detail to understand the initial and modified wetting properties. Furthermore, the temporal evolutions of different droplet parameters are investigated to realize the interactions between the water droplet, the sample surface and the atmosphere. We envisage that such modified surfaces can be beneficial for transport of a small volume of liquids with minimum loss and spectroscopic studies, where a small amount of water droplet is available for measurements. PMID:26420552

  5. Influence of the Ar-ion irradiation on the giant magnetoresistance in Fe/Cr multilayers

    NASA Astrophysics Data System (ADS)

    Kopcewicz, M.; Stobiecki, F.; Jagielski, J.; Szyma?ski, B.; Schmidt, M.; Dubowik, J.; Kalinowska, J.

    2003-05-01

    The influence of 200 keV Ar-ion irradiation on the interlayer coupling in Fe/Cr multilayers exhibiting the giant magnetoresistance (GMR) effect is studied by the conversion electron Mössbauer spectroscopy (CEMS), vibrating sample magnetometer hysteresis loops, magnetoresistivity, and electric resistivity measurements and supplemented by the small-angle x-ray diffraction. The increase of Ar-ion dose causes an increase of interface roughness, as evidenced by the increase of the Fe step sites detected by CEMS. The modification of microstructure induces changes in magnetization reversal indicating a gradual loss of antiferromagnetic (AF) coupling correlated with the degradation of the GMR effect. Distinctly weaker degradation of AF coupling and the GMR effect observed for irradiated samples with a thicker Cr layer thickness suggest that observed effects are caused by pinholes creation. The measurements of temperature dependence of remanence magnetization confirm increase of pinhole density and sizes during implantation. Other effects which can influence spin dependent contribution to the resistance, such as interface roughness as well as shortening of mean-free path of conduction electrons, are also discussed.

  6. Investigation of VLSI Bipolar Transistors Irradiated with Electrons, Ions and Neutrons for Space Application

    NASA Astrophysics Data System (ADS)

    D'Angelo, P.; Fallica, G.; Galbiati, A.; Mangoni, R.; Modica, R.; Pensotti, S.; Rancoita, P. G.

    2006-04-01

    A systematic investigation of radiation effects on a BICMOS technology manufactured by STM has been undertaken. Bipolar transistors were irradiated by neutrons, C, Ar and Kr ions, and recently by electrons. Fast neutrons, as well as other types of particles, produce defects mainly by displacing silicon atoms from their lattice positions to interstitial locations, i.e. generating vacancy-interstitial pairs (the so-called Frenkel pairs). Although imparted doses differ largely, the experimental results indicate that the gain (?) variation is mostly related to the non-ionizing energy-loss (NIEL) deposition for neutrons, ions and electrons. The variation of the inverse of the gain degradation, ?(1/?), is found to be linearly related (as predicted by the Messenger-Spratt equation for neutron irradiations) to the concentrations of the Frenkel pairs generated independently of the kind of incoming particle. For space applications, this linear dependence on the concentration of Frenkel pairs allows to evaluate the total amount of the gain degradation of VLSI components due to the flux of charged particles during the full life of operation of any pay-load. In fact, the total amount of expected Frenkel pairs can be estimated taking into account the isotopic spectra. It has to be point out that in cosmic rays there is relevant flux of electrons and isotopes up to Ni, which are within the range of particles presently investigated.

  7. Ion irradiation testing and characterization of FeCrAl candidate alloys

    SciTech Connect

    Anderoglu, Osman; Aydogan, Eda; Maloy, Stuart Andrew; Wang, Yongqiang

    2014-10-29

    The Fuel Cycle Research and Development program’s Advanced Fuels Campaign has initiated a multifold effort aimed at facilitating development of accident tolerant fuels. This effort involves development of fuel cladding materials that will be resistant to oxidizing environments for extended period of time such as loss of coolant accident. Ferritic FeCrAl alloys are among the promising candidates due to formation of a stable Al?O? oxide scale. In addition to being oxidation resistant, these promising alloys need to be radiation tolerant under LWR conditions (maximum dose of 10-15 dpa at 250 – 350°C). Thus, in addition to a number of commercially available alloys, nuclear grade FeCrAl alloys developed at ORNL were tested using high energy proton irradiations and subsequent characterization of irradiation hardening and damage microstructure. This report summarizes ion irradiation testing and characterization of three nuclear grade FeCrAl cladding materials developed at ORNL and four commercially available Kanthal series FeCrAl alloys in FY14 toward satisfying FCRD campaign goals.

  8. Emission of organic products from the surface of frozen methane under MeV ion irradiation

    NASA Astrophysics Data System (ADS)

    Kaiser, R. I.; Mahfouz, R. M.; Roessler, K.

    1992-03-01

    10 ?m layers of CH 4 freshly condensed onto a cold finger at 10-15 K were irradiated with 10-20 MeV protons and 3He 2+ ions. The gases emitted during irradiation and successive warming to ambient temperature were monitored by quadrupole mass spectrometry (QMS). C 2H 2 and C 2H 4 were the primary volatile products at low temperatures. They were converted with increasing irradiation time and dose into C 2H 6, C 3H 6 and heavier hydrocarbons up to C 8. During the warmup phase even more complex hydrocarbons up to C 12 were emitted including substituted benzenes (xylols), naphthalene derivates and anthracene and/or phenanthrene. The preferential formation of unsaturated compounds in the first reaction steps underlines the role of hot carbon atoms in the radiation induced complexation of solid organic matter, starting with their insertion into C?H bonds. The interaction of cosmic rays with organic solids in space includes these suprathermal reactions as one of the most prominent processes.

  9. Ion, X-Ray, UV And Neutron Microbeam Systems For Cell Irradiation

    SciTech Connect

    Bigelow, A. W.; Randers-Pehrson, G.; Garty, G.; Geard, C. R.; Xu, Y.; Harken, A. D.; Johnson, G. W.; Brenner, D. J.

    2011-06-01

    The array of microbeam cell-irradiation systems, available to users at the Radiological Research Accelerator Facility (RARAF), Center for Radiological Research, Columbia University, is expanding. The HVE 5MV Singletron particle accelerator at the facility provides particles to two focused ion microbeam lines: the sub-micron microbeam II and the permanent magnetic microbeam (PMM). Both the electrostatic quadrupole lenses on the microbeam II system and the magnetic quadrupole lenses on the PMM system are arranged as compound lenses consisting of two quadrupole triplets with 'Russian' symmetry. Also, the RARAF accelerator is a source for a proton-induced x-ray microbeam (undergoing testing) and is projected to supply protons to a neutron microbeam based on the {sup 7}Li(p,n){sup 7}Be nuclear reaction (under development). Leveraging from the multiphoton microscope technology integrated within the microbeam II endstation, a UV microspot irradiator - based on multiphoton excitation - is available for facility users. Highlights from radiation-biology demonstrations on single living mammalian cells are included in this review of microbeam systems for cell irradiation at RARAF.

  10. Ion, X-Ray, UV And Neutron Microbeam Systems For Cell Irradiation

    NASA Astrophysics Data System (ADS)

    Bigelow, A. W.; Randers-Pehrson, G.; Garty, G.; Geard, C. R.; Xu, Y.; Harken, A. D.; Johnson, G. W.; Brenner, D. J.

    2011-06-01

    The array of microbeam cell-irradiation systems, available to users at the Radiological Research Accelerator Facility (RARAF), Center for Radiological Research, Columbia University, is expanding. The HVE 5MV Singletron particle accelerator at the facility provides particles to two focused ion microbeam lines: the sub-micron microbeam II and the permanent magnetic microbeam (PMM). Both the electrostatic quadrupole lenses on the microbeam II system and the magnetic quadrupole lenses on the PMM system are arranged as compound lenses consisting of two quadrupole triplets with "Russian" symmetry. Also, the RARAF accelerator is a source for a proton-induced x-ray microbeam (undergoing testing) and is projected to supply protons to a neutron microbeam based on the 7Li(p,n)7Be nuclear reaction (under development). Leveraging from the multiphoton microscope technology integrated within the microbeam II endstation, a UV microspot irradiator—based on multiphoton excitation—is available for facility users. Highlights from radiation-biology demonstrations on single living mammalian cells are included in this review of microbeam systems for cell irradiation at RARAF.

  11. Systematic investigation of monolithic bipolar transistors irradiated with neutrons, heavy ions and electrons for space applications

    NASA Astrophysics Data System (ADS)

    Consolandi, C.; D'Angelo, P.; Fallica, G.; Mangoni, R.; Modica, R.; Pensotti, S.; Rancoita, P. G.

    2006-11-01

    In this paper, experimental results of radiation effects on a BiCMOS high speed commercial technology, manufactured by ST-Microelectronics, are reported after irradiation with 9.1 MeV electrons. The data are compared with those previously obtained by irradiations with fast-neutrons, 12C-, 13C-, Ar- and Kr-ions. Fast-neutrons, as well as other types of particles, produce defects, mainly by displacing silicon atoms from their lattice positions to interstitial locations, i.e. generating vacancy-interstitial pairs, the so-called Frenkel pairs, which results in creating recombination centers. As a consequence, the lifetime of the minority-carriers in the base is decreased and the common-emitter current gain ( ?) is degraded. The gain degradation was investigated for collector current Ic between 1 ?A and 1 mA. The linear dependence of ?(1/ ?) = 1/ ?irr - 1/ ? (where ?irr and ? are the gain after and before the irradiation) as a function of the concentration of Frenkel pairs was confirmed. The bipolar transistors made on this technology have shown to be particularly radiation resistant. Base and collector currents were systematically investigated, as well as, the effect of self-annealing.

  12. Evolution of surface morphology and electronic structure of few layer graphene after low energy Ar{sup +} ion irradiation

    SciTech Connect

    Al-Harthi, S. H.; Kara'a, A.; Elzain, M.; Hysen, T.; Al-Hinai, A. T.; Myint, M. T. Z.

    2012-11-19

    We report on co-existing dual anisotropy ripple formation, sp bonding transformation, and variation in the delocalized {pi} electron system in 1 keV Ar{sup +} ion irradiated few-layer graphene surfaces. Ripples in directions, perpendicular and parallel to the ion beam were found. The irradiation effect and the transition from the sp{sup 2}-bonding to sp{sup 3}-hybridized state were analyzed from the deconvolution of the C (1s) peak and from the shape of the derivative of the Auger transition spectra. The results suggest a plausible mechanism for tailoring of few-layer graphene electronic band structure with interlayer coupling tuned by the ion irradiation.

  13. Modification of interface magnetic anisotropy by ion irradiation on epitaxial Cu/Ni/Cu(002)/ Si(100) films

    NASA Astrophysics Data System (ADS)

    Lee, J.-S.; Lee, K.-B.; Park, Y. J.; Kim, T. G.; Song, J. H.; Chae, K. H.; Lee, J.; Whang, C. N.; Jeong, K.; Kim, D.-H.; Shin, S.-C.

    2004-05-01

    Various x-ray scattering and magnetic measurements were employed to reveal changes in intrinsic structural and magnetic properties on epitaxial Cu/Ni(t)/Cu(002)/Si(100) thin films (t=20, 30, 60, and 90 Å) before and after 1 MeV C+ ion irradiation. Torque magnetometer and grazing incidence x-ray diffraction measurements were carried out to understand relation between magnetic and structural properties, respectively. X-ray reflectivity measurements were performed to characterize interface roughness and intermixing. It is observed that effective magnetic anisotropy values of ion-irradiated films are negative over the entire nickel thickness range and the dominant factor of the reorientation of magnetic easy axis from surface normal to surface parallel is reduction of the interface magnetic anisotropy coefficient in spite of decreased interface mixing after ion irradiation.

  14. Miniaturized disk-bend testing, nano-indentation and the microstructure of ion-irradiated titanium aluminides

    SciTech Connect

    Petouhoff, N.L.; Ardell, A.J.; Oliver, W.C.; Lucas, B.N.

    1993-09-01

    Effect of ion irradiation on microstructures and mechanical properties of Ti-52Al (TiAl) and Ti-26Al (Ti{sub 3}Al) were investigated. The alloys were irradiated with 2 MeV protons and Ar{sup +} ions at low temperatures ({minus}175 to {minus}135C) to max fluences of 4.5 {times} 10{sup 15} Ar{sup +}/cm{sup 2} and 2 {times} 10{sup 17} H{sup +}/cm{sup 2}. Yield strengths of unirradiated TiAl and the fracture strength of unirradiated Ti{sub 3}Al were 367 {plus_minus} 33 MPa and 536 {plus_minus} 30 MPa, respectively, in excellent agreement with published data. Yield strength of TiAl and fracture strength of Ti{sub 3}Al increased as a result of irradiation. Strengths of both alloys were lowest for the samples irradiated to the highest Ar{sup +}-ion dose, but otherwise there was no correlation of strength with dose. The nanohardness of irradiated specimens generally increased with dose, but influence of dose on Young`s modulus was erratic. Plate-shaped defects vacancy in character, and helical dislocations were observed in irradiated TiAl by TEM. The Ar{sup +}-ion irradiation-induced microstructure of Ti{sub 3}Al contained defects producing mottled contrast at 1 dpa and black-spot contrast at 5 dpa. Irradiation-induced loss of long-range order was also observed in both alloys. Influence of these microstructural variables on mechanical behavior is discussed.

  15. Reprint of Localized dose delivering by ion beam irradiation for experimental trial of establishing brain necrosis model.

    PubMed

    Takata, Takushi; Kondo, Natsuko; Sakurai, Yoshinori; Tanaka, Hiroki; Hasegawa, Takashi; Kume, Kyo; Suzuki, Minoru

    2015-12-01

    Localized dose delivery techniques to establish a brain radiation necrosis model are described. An irradiation field was designed by using accelerated protons or helium ions with a spread-out Bragg peak. Measurement of the designed field confirmed that a high dose can be confined to a local volume of an animal brain. The irradiation techniques described here are very useful for establishing a necrosis model without existence of extraneous complications. PMID:26515136

  16. Formation of ion tracks in amorphous silicon nitride films with MeV C60 ions

    NASA Astrophysics Data System (ADS)

    Kitayama, T.; Morita, Y.; Nakajima, K.; Narumi, K.; Saitoh, Y.; Matsuda, M.; Sataka, M.; Tsujimoto, M.; Isoda, S.; Toulemonde, M.; Kimura, K.

    2015-08-01

    Amorphous silicon nitride (a-SiN) films (thickness 5-100 nm) were irradiated with 0.12-5 MeV C60, 100 MeV Xe, 200 MeV Kr, and 200 and 420 MeV Au ions. Ion tracks were clearly observed using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) except for 100 MeV Xe and 200 MeV Kr. The observed HAADF-STEM images showed that the ion tracks consist of a low density core (0.5-2 nm in radius) and a high density shell (several nm in radius). The observed core and shell radii are not simply correlated with the electronic energy loss indicating that the nuclear energy loss plays an important role in the both core and shell formations. The observed track radii were well reproduced by the unified thermal spike model with two thresholds for shell and core formations.

  17. Role of isolated and clustered DNA damage and the post-irradiating repair process in the effects of heavy ion beam irradiation.

    PubMed

    Tokuyama, Yuka; Furusawa, Yoshiya; Ide, Hiroshi; Yasui, Akira; Terato, Hiroaki

    2015-05-01

    Clustered DNA damage is a specific type of DNA damage induced by ionizing radiation. Any type of ionizing radiation traverses the target DNA molecule as a beam, inducing damage along its track. Our previous study showed that clustered DNA damage yields decreased with increased linear energy transfer (LET), leading us to investigate the importance of clustered DNA damage in the biological effects of heavy ion beam radiation. In this study, we analyzed the yield of clustered base damage (comprising multiple base lesions) in cultured cells irradiated with various heavy ion beams, and investigated isolated base damage and the repair process in post-irradiation cultured cells. Chinese hamster ovary (CHO) cells were irradiated by carbon, silicon, argon and iron ion beams with LETs of 13, 55, 90 and 200 keV µm(-1), respectively. Agarose gel electrophoresis of the cells with enzymatic treatments indicated that clustered base damage yields decreased as the LET increased. The aldehyde reactive probe procedure showed that isolated base damage yields in the irradiated cells followed the same pattern. To analyze the cellular base damage process, clustered DNA damage repair was investigated using DNA repair mutant cells. DNA double-strand breaks accumulated in CHO mutant cells lacking Xrcc1 after irradiation, and the cell viability decreased. On the other hand, mouse embryonic fibroblast (Mef) cells lacking both Nth1 and Ogg1 became more resistant than the wild type Mef. Thus, clustered base damage seems to be involved in the expression of heavy ion beam biological effects via the repair process. PMID:25717060

  18. Role of isolated and clustered DNA damage and the post-irradiating repair process in the effects of heavy ion beam irradiation

    PubMed Central

    Tokuyama, Yuka; Furusawa, Yoshiya; Ide, Hiroshi; Yasui, Akira; Terato, Hiroaki

    2015-01-01

    Clustered DNA damage is a specific type of DNA damage induced by ionizing radiation. Any type of ionizing radiation traverses the target DNA molecule as a beam, inducing damage along its track. Our previous study showed that clustered DNA damage yields decreased with increased linear energy transfer (LET), leading us to investigate the importance of clustered DNA damage in the biological effects of heavy ion beam radiation. In this study, we analyzed the yield of clustered base damage (comprising multiple base lesions) in cultured cells irradiated with various heavy ion beams, and investigated isolated base damage and the repair process in post-irradiation cultured cells. Chinese hamster ovary (CHO) cells were irradiated by carbon, silicon, argon and iron ion beams with LETs of 13, 55, 90 and 200 keV µm?1, respectively. Agarose gel electrophoresis of the cells with enzymatic treatments indicated that clustered base damage yields decreased as the LET increased. The aldehyde reactive probe procedure showed that isolated base damage yields in the irradiated cells followed the same pattern. To analyze the cellular base damage process, clustered DNA damage repair was investigated using DNA repair mutant cells. DNA double-strand breaks accumulated in CHO mutant cells lacking Xrcc1 after irradiation, and the cell viability decreased. On the other hand, mouse embryonic fibroblast (Mef) cells lacking both Nth1 and Ogg1 became more resistant than the wild type Mef. Thus, clustered base damage seems to be involved in the expression of heavy ion beam biological effects via the repair process. PMID:25717060

  19. Three-photon-excited upconversion luminescence of niobium ions doped silicate glass by a femtosecond laser irradiation.

    PubMed

    Zeng, Huidan; Song, Juan; Chen, Danping; Yuan, Shuanglong; Jiang, Xiongwei; Cheng, Ya; Yang, Yunxia; Chen, Guorong

    2008-04-28

    We report on the bluish green upconversion luminescence of niobium ions doped silicate glass by a femtosecond laser irradiation. The dependence of the fluorescence intensity on the pump power density of laser indicates that the conversion of infrared irradiation to visible emission is dominated by three-photon excitation process. We suggest that the charge transfer from O(2-) to Nb(5+) can efficiently contribute to the bluish green emission. The results indicate that transition metal ions without d electrons play an important role in fields of optics when embedded into silicate glass matrix. PMID:18545353

  20. Comparison of the Effects of Carbon Ion and Photon Irradiation on the Angiogenic Response in Human Lung Adenocarcinoma Cells

    SciTech Connect

    Kamlah, Florentine; Haenze, Joerg; Arenz, Andrea; Seay, Ulrike; Hasan, Diya; Gottschald, Oana R.; Seeger, Werner; Rose, Frank

    2011-08-01

    Purpose: Radiotherapy resistance is a commonly encountered problem in cancer treatment. In this regard, stabilization of endothelial cells and release of angiogenic factors by cancer cells contribute to this problem. In this study, we used human lung adenocarcinoma (A549) cells to compare the effects of carbon ion and X-ray irradiation on the cells' angiogenic response. Methods and Materials: A549 cells were irradiated with biologically equivalent doses for cell survival of either carbon ions (linear energy transfer, 170 keV/{mu}m; energy of 9.8 MeV/u on target) or X-rays and injected with basement membrane matrix into BALB/c nu/nu mice to generate a plug, allowing quantification of angiogenesis by blood vessel enumeration. The expression of angiogenic factors (VEGF, PlGF, SDF-1, and SCF) was assessed at the mRNA and secreted protein levels by using real-time reverse transcription-PCR and enzyme-linked immunosorbent assay. Signal transduction mediated by stem cell factor (SCF) was assessed by phosphorylation of its receptor c-Kit. For inhibition of SCF/c-Kit signaling, a specific SCF/c-Kit inhibitor (ISCK03) was used. Results: Irradiation of A549 cells with X-rays (6 Gy) but not carbon ions (2 Gy) resulted in a significant increase in blood vessel density (control, 20.71 {+-} 1.55; X-ray, 36.44 {+-} 3.44; carbon ion, 16.33 {+-} 1.03; number per microscopic field). Concordantly, irradiation with X-rays but not with carbon ions increased the expression of SCF and subsequently caused phosphorylation of c-Kit in endothelial cells. ISCK03 treatment of A549 cells irradiated with X-rays (6 Gy) resulted in a significant decrease in blood vessel density (X-ray, 36.44 {+-} 3.44; X-ray and ISCK03, 4.33 {+-} 0.71; number of microscopic field). These data indicate that irradiation of A549 cells with X-rays but not with carbon ions promotes angiogenesis. Conclusions: The present study provides evidence that SCF is an X-ray-induced mediator of angiogenesis in A549 cells, a phenomenon that could not be observed with carbon ion irradiation. Thus, in this model system evaluating angiogenesis, carbon ion irradiation may have a therapeutic advantage. This observation should be confirmed in orthotopic lung tumor models.

  1. Effect of thermal neutron irradiation on Gd{sup 3+} ions doped in oxyfluoroborate glass: an infra-red study

    SciTech Connect

    Kumar, Akshaya; Rai, S.B.; Rai, D.K

    2003-01-25

    Infrared spectra of oxyfluoroborate glasses of composition (70-x)H{sub 3}BO{sub 3}+20Li{sub 2}CO{sub 3}+xGd{sub 2}O{sub 3}, where x=0, 0.5, 1.0, 3.0 and 5.0 mol%, have been recorded to explore the role of Gd{sup 3+} ions in the structure of the glasses. We concluded that Gd{sup 3+} ion behaves as a glass modifier. The effect of thermal neutron irradiation on the structure of these glasses also has been explored and the changes compared with earlier results on {gamma}-irradiation.

  2. Enhanced susceptibility of CaF 2(1 1 1) to adsorption due to ion irradiation

    NASA Astrophysics Data System (ADS)

    Akcöltekin, S.; Roll, T.; Akcöltekin, E.; Klusmann, M.; Lebius, H.; Schleberger, M.

    2009-02-01

    We have investigated morphological changes of freshly cleaved CaF2(1 1 1) single crystal surfaces before and after ion irradiation. We show that with or without irradiation the surface undergoes serious changes within minutes after the cleavage if the samples are exposed to ambient conditions. This is most likely due to the adsorption of water and could be avoided only if working under clean ultra-high-vacuum conditions. Ion-induced modifications on this surface seem to act as centers for an increased rate of adsorption so that any quantitative numbers obtained by atomic force microscopy in such experiments have to be treated with caution.

  3. Temperature-dependent surface modification of Ta due to high-flux, low-energy He+ ion irradiation

    NASA Astrophysics Data System (ADS)

    Novakowski, T. J.; Tripathi, J. K.; Hassanein, A.

    2015-12-01

    This work examines the response of Tantalum (Ta) as a potential candidate for plasma-facing components (PFCs) in future nuclear fusion reactors. Tantalum samples were exposed to high-flux, low-energy He+ ion irradiation at different temperatures in the range of 823-1223 K. The samples were irradiated at normal incidence with 100 eV He+ ions at constant flux of 1.2 × 1021 ions m-2 s-1 to a total fluence of 4.3 × 1024 ions m-2. An additional Ta sample was also irradiated at 1023 K using a higher ion fluence of 1.7 × 1025 ions m-2 (at the same flux of 1.2 × 1021 ions m-2 s-1), to confirm the possibility of fuzz formation at higher fluence. This higher fluence was chosen to roughly correspond to the lower fluence threshold of fuzz formation in Tungsten (W). Surface morphology was characterized with a combination of field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). These results demonstrate that the main mode of surface damage is pinholes with an average size of ?70 nm2 for all temperatures. However, significantly larger pinholes are observed at elevated temperatures (1123 and 1223 K) resulting from the agglomeration of smaller pinholes. Ex situ X-ray photoelectron spectroscopy (XPS) provides information about the oxidation characteristics of irradiated surfaces, showing minimal exfoliation of the irradiated Ta surface. Additionally, optical reflectivity measurements are performed to further characterize radiation damage on Ta samples, showing gradual reductions in the optical reflectivity as a function of temperature.

  4. Quasi-Particle Excited Bands in 129Xe

    NASA Astrophysics Data System (ADS)

    Pasi, Virendra Kumar; Das, Pragya; Bhujang, Bhushan; Biswas, S.; Saha, S.; Sethi, J.; Biswas, D. C.; Palit, R.

    The 129Xe nucleus has been investigated using the techniques of ?-ray spectroscopy. The heavy-ion fusion reaction 124Sn(11B, p5n)129Xe was utilized at the beam energy of 70 MeV. Three new quasi-particle bands have been identified. From our polarization results, the yrast band was confirmed to have negative parity. However, the parity of the bandhead of an excited quasi-particle band was changed from negative to positive. In the yrast band, the backbending was found to be due to the alignment of neutrons.

  5. Precision Penning Trap Mass Spectrometry of S, Kr and Xe

    NASA Astrophysics Data System (ADS)

    Redshaw, Matthew

    2005-04-01

    Using a phase coherent technique to measure the cyclotron frequency of single ions in a Penning trap [1], we have performed mass measurements on ^32S and the two most abundant krypton and xenon isotopes ^84Kr, ^86Kr, ^ 129Xe and ^132Xe, to relative precisions of 0.1 ppb. This is a factor of ˜10-100 improvement in precision over current values [2]. [1] M.P. Bradley, J.V. Porto, S. Rainville, J.K. Thompson, and D.E. Pritchard, PRL 83, 4510 (1999). [2] G. Audi, A.H. Wapstra, and C. Thibault, Nucl Phys A729, 337 (2003).

  6. Removal of metal ions from wastewater using EB irradiation in combination with HA/TiO?/UV treatment.

    PubMed

    Zaki, A A; El-Gendy, Naima A

    2014-04-30

    The electron beam (EB) irradiation technology was applied for removal of Cu(2+), Sr(2+), and Co(2+) ions from wastewater. The aim of this study is to achieve an efficient treatment process of wastewater using EB and introducing a combination of humic acid (HA) as a natural organic polymer and ultraviolet irradiation of a TiO2 (TiO2/UV), as a suspended catalyst in the treatment of wastewater solutions (TiO2/UV+HA). The experimental results showed that the percentage removal of Cu(2+), Sr(2+), and Co(2+)ions was 41%, 87% and 75% respectively, at 125 kGy. In the presence of TiO2 photocatalyst and exposure of the investigated wastewater to ultraviolet rays before irradiation by the EB the percentage removal of Cu(2+) ions became 51%, while the percentage removal of both Sr(2+) and Co(2+) ions was slightly improved; was 87% and 75%, respectively at the same EB dose. On the other hand, by introducing the combination of TiO2/UV+HA, only an irradiation dose of about 50kGy led to removal of Cu(2+), Sr(2+), and Co(2+) completely from the wastewater. Mechanisms of interactions between HA and Cu(2+), Co(2+) and Sr(2+) metal ions were suggested and discussed. PMID:24637452

  7. Ion irradiation as a tool for modifying the surface and optical properties of plasma polymerised thin films

    NASA Astrophysics Data System (ADS)

    Grant, Daniel S.; Bazaka, Kateryna; Siegele, Rainer; Holt, Stephen A.; Jacob, Mohan V.

    2015-10-01

    Radio frequency (R.F.) glow discharge polyterpenol thin films were prepared on silicon wafers and irradiated with I10+ ions to fluences of 1 × 1010 and 1 × 1012 ions/cm2. Post-irradiation characterisation of these films indicated the development of well-defined nano-scale ion entry tracks, highlighting prospective applications for ion irradiated polyterpenol thin films in a variety of membrane and nanotube-fabrication functions. Optical characterisation showed the films to be optically transparent within the visible spectrum and revealed an ability to selectively control the thin film refractive index as a function of fluence. This indicates that ion irradiation processing may be employed to produce plasma-polymer waveguides to accommodate a variety of wavelengths. XRR probing of the substrate-thin film interface revealed interfacial roughness values comparable to those obtained for the uncoated substrate's surface (i.e., both on the order of 5 Å), indicating minimal substrate etching during the plasma deposition process.

  8. Surface Etching and DNA Damage Induced by Low-Energy Ion Irradiation in Yeast

    NASA Astrophysics Data System (ADS)

    Liu, Xuelan; Xu, An; Dai, Yin; Yuan, Hang; Yu, Zengliang

    2011-06-01

    Bio-effects of survival and etching damage on cell surface and DNA strand breaks were investigated in the yeast saccharomyces cerevisiae after exposure by nitrogen ion with an energy below 40 keV. The result showed that 16% of trehalose provided definite protection for cells against vacuum stress compared with glycerol. In contrast to vacuum control, significant morphological damage and DNA strand breaks were observed, in yeast cells bombarded with low-energy nitrogen, by scanning electron microscopy (SEM) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) immunofluorescence assays. Moreover, PI (propidium iodide) fluorescent staining indicated that cell integrity could be destroyed by ion irradiation. Cell damage eventually affected cell viability and free radicals were involved in cell damage as shown by DMSO (dimethyl sulfoxide) rescue experiment. Our primary experiments demonstrated that yeast cells can be used as an optional experimental model to study the biological effects of low energy ions and be applied to further investigate the mechanism(s) underlying the bio-effects of eukaryotic cells.

  9. The dependence of stress in IBAD films on the ion-irradiation energy and flux

    NASA Astrophysics Data System (ADS)

    Schweitz, K. O.; Arndt, J.; Bøttiger, J.; Chevallier, J.

    1997-05-01

    Systematic experimental studies of the stress build-up during e-gun deposition of Ni with simultaneous bombardment by energetic Ar + ions (IBAD) have been carried out. The ion energy E was varied from 60 to 800 eV, and the ratio of the arrival rates of Ni atoms and Ar + ions, {R}/{J}, was varied from 0.5 to 6.4. The Ni-deposition rate was in the range from 0.5 to 2.0 Å/s, with all the depositions carried out near room temperature in a chamber with the base pressure of 5 × 10 -6 Pa. The film stress was measured by use of profilometry and the application of Stoney's equation. The experimental results were compared with predictions of a simple model proposed by Davis. This model assumes that the compressive stress build-up, due to knock-on implantation of film atoms being proportional to E {1}/{2}, is balanced by relaxation by collision-cascade-excited atom migration proportional to E {5}/{3}. To obtain agreement between model and experiment in the investigated ranges of E and {R}/{J}, an additional model parameter had to be added which takes into account that without irradiation, tensile stresses arise.

  10. Swift heavy ion irradiation-induced amorphization of La2Ti2O7

    NASA Astrophysics Data System (ADS)

    Park, Sulgiye; Lang, Maik; Tracy, Cameron L.; Zhang, Jiaming; Zhang, Fuxiang; Trautmann, Christina; Kluth, Patrick; Rodriguez, Matias D.; Ewing, Rodney C.

    2014-05-01

    Polycrystalline La2Ti2O7 powders have been irradiated with 2.0 GeV 181Ta ions up to a fluence of 1 × 1013 ions/cm2. Radiation-induced structural modifications were analyzed using synchrotron-based X-ray diffraction (XRD), small angle X-ray scattering (SAXS), Raman spectroscopy and transmission electron microscopy (TEM). An increase in the amorphous fraction as a function of fluence was revealed by XRD and Raman analyses and is evidenced by the reduction in intensity of the sharp Bragg maxima from the crystalline regions. Concurrently, diffraction maxima and vibrational absorption bands broaden with the increasing amorphous fraction. The cross-section for the crystalline-to-amorphous transformation (ion tracks) was determined by quantitative analysis of XRD patterns yielding a track diameter of d = 7.2 ± 0.9 nm. Slightly larger track diameters were obtained directly from TEM images (d = 10.6 ± 0.8 nm) and SAXS analysis (d = 10.6 ± 0.3 nm). High-resolution TEM images revealed that single tracks are entirely amorphous without any outer crystalline, disordered shell as found in pyrochlore oxides of the same stoichiometry. The large ratio of ionic radii of the A- and B-site cations (rA/rB = 1.94) means that disordering over the A- and B-sites is energetically unfavorable.

  11. Inactivation, mutation induction and repair in Bacillus subtilis spores irradiated with heavy ions.

    PubMed

    Horneck, G; Bucker, H

    1983-01-01

    Studies on the response of bacterial spores to accelerated heavy ions (HZE particles) help in understanding problems of space radiobiology and exobiology. Layers of spores of Bacillus subtilis strains, differing in repair capabilities, were irradiated with accelerated boron, carbon and neon ions of linear energy transfer (LET) values up to 14000 MeV cm2/g. Inactivation as measured by loss of colony forming ability and induction of mutations as measured by reversion to histidine prototrophy and resistance to 150 micrograms/ml sodium azide were tested, as well as the influence of repair processes on these effects. For inactivation, the cross-sectional values sigma plotted as a function of LET follow a saturation curve. The plateau, which is reached around a LET of 2000 MeV cm2/g, occurs at 2.5 x 10(-9) cm2, a value in good agreement with the dimensions of the spore protoplast. Lethal damage produced at LET values < 2000 MeV cm2/g is reparable. Recombination repair is more effective than excision repair. At higher LET values, lethal damage could not be reconstituted by the repair mechanisms studied. In addition, at these high LET values, the frequency of induced mutations was drastically decreased. The data support the assumption of at least two qualitatively different types of lesion, depending on the LET of the affecting heavy ion. PMID:11542759

  12. MARMOT simulations of Xe segregation to grain boundaries in UO2

    SciTech Connect

    Andersson, Anders D.; Tonks, Michael; Casillas, Luis; Millett, Paul; Vyas, Shyam; Uberuaga, Blas P.; Nerikar, Pankaj

    2012-06-20

    Diffusion of Xe and U in UO{sub 2} is controlled by vacancy mechanisms and under irradiation the formation of mobile vacancy clusters is important. We derive continuum thermodynamic and diffusion models for Xe and U in UO{sub 2} based on the vacancy and cluster diffusion mechanisms established from recent density functional theory (DFT) calculations. Segregation of defects to grain boundaries in UO{sub 2} is described by combining the diffusion model with models of the interaction between Xe atoms and vacancies with grain boundaries derived from separate atomistic calculations. The diffusion and segregation models are implemented in the MOOSE/MARMOT (MBM) finite element (FEM) framework and we simulate Xe redistribution for a few simple microstructures. In this report we focus on segregation to grain boundaries. The U or vacancy diffusion model as well as the coupled diffusion of vacancies and Xe have also been implemented, but results are not included in this report.

  13. Influence of electronic energy deposition on the structural modification of swift heavy-ion-irradiated amorphous germanium layers

    SciTech Connect

    Steinbach, T.; Schnohr, C. S.; Wesch, W.; Kluth, P.; Giulian, R.; Araujo, L. L.; Sprouster, D. J.; Ridgway, M. C.

    2011-02-01

    Swift heavy-ion (SHI) irradiation of amorphous germanium (a-Ge) layers leads to a strong volume expansion accompanied by a nonsaturating irreversible plastic deformation (ion hammering), which are consequences of the high local electronic energy deposition within the region of the a-Ge layer. We present a detailed study of the influence of SHI irradiation parameters on the effect of plastic deformation and structural modification. Specially prepared a-Ge layers were irradiated using two SHI energies and different angles of incidence, thus resulting in a variation of the electronic energy deposition per depth {epsilon}{sub e} between 14.0 and 38.6 keV nm{sup -1}. For all irradiation parameters used a strong swelling of the irradiated material was observed, which is caused by the formation and growth of randomly distributed voids, leading to a gradual transformation of the amorphous layer into a sponge-like porous structure as established by cross-section scanning electron microscopy investigations. The swelling depends linearly on the ion fluence and on the value of {epsilon}{sub e}, thus clearly demonstrating that the structural changes are determined solely by the electronic energy deposited within the amorphous layer. Plastic deformation shows a superlinear dependence on the ion fluence due to the simultaneous volume expansion. This influence of structural modification on plastic deformation is described by a simple approach, thus allowing estimation of the deformation yield. With these results the threshold values of the electronic energy deposition for the onset of both structural modification and plastic deformation due to SHI irradiation are determined. Furthermore, based on these results, the longstanding question concerning the reason for the structural modification observed in SHI-irradiated crystalline Ge is answered.

  14. Formation of ion irradiation-induced atomic-scale defects on walls of carbon nanotubes A. V. Krasheninnikova b, K. Nordlundb, M. Sirviob, E. Salonenb and J. Keinonenb

    E-print Network

    Nordlund, Kai

    structure and formation probabilities of atomic-scale defects produced by low-dose irradi- ationFormation of ion irradiation-induced atomic-scale defects on walls of carbon nanotubes A. V.O. Box 43, FIN-00014 University of Helsinki, Finland (March 20, 2001) Recent experiments on irradiated

  15. Ion-irradiation-induced clustering in WRe and WReOs alloys: A comparative study using atom probe tomography and nanoindentation

    E-print Network

    Ion-irradiation-induced clustering in W­Re and W­Re­Os alloys: A comparative study using atom probe irradiation at 573 and 773 K. Such clusters are known precursors to the formation of embrittling precipitates were studied using nanoindentation. The presence of osmium significantly increased post- irradiation

  16. Heats of Formation of XeF??, XeF??, XeF??, XeF??, XeF??,and XeF? from High Level Electronic Structure Calculations

    SciTech Connect

    Grant, Daniel J.; Wang, Tsang-Hsiu; Dixon, David A.; Christe, Karl O.

    2010-01-04

    Atomization energies at 0 K and heats of formation at 0 and 298 K are predicted for XeF??, XeF??, XeF??, XeF??, and XeF? from coupled cluster theory (CCSD(T)) calculations with effective core potential correlation-consistent basis sets for Xe and including correlation of the nearest core electrons. Additional corrections are included to achieve near chemical accuracy of ±1 kcal/mol. Vibrational zero point energies were computed at the MP2 level of theory. Unlike the other neutral xenon fluorides, XeF? is predicted to be thermodynamically unstable with respect to loss of F? with the reaction calculated to be exothermic by 22.3 kcal/mol at 0 K. XeF?? is also predicted to be thermodynamically unstable with respect to the loss of F? by 24.1 kcal/mol at 0 K. For XeF??, XeF??, XeF??, XeF?? and XeF??, the reactions for loss of F? are endothermic by 14.8, 37.8, 38.2, 59.6, and 31.9 kcal/mol at 0 K, respectively. The F? affinities of Xe, XeF?, XeF?, and XeF? are predicted to be 165.1, 155.3, 172.7, and 132.5 kcal/mol, and the corresponding F? affinities are 6.3, 19.9, 59.1, and 75.0 kcal/mol at 0 K, respectively.

  17. Enhancement in electron field emission in ultrananocrystalline and microcrystalline diamond films upon 100 MeV silver ion irradiation

    SciTech Connect

    Chen, H.-C.; Palnitkar, Umesh; Pong, W.-F.; Lin, I-N.; Singh, Abhinav Pratap; Kumar, Ravi

    2009-04-15

    Enhanced electron field emission (EFE) behavior was observed in ultrananocrystalline diamond (UNCD) and microcrystalline diamond (MCD) films upon irradiation with 100 MeV Ag{sup 9+}-ions in a fluence of 5x10{sup 11} ions/cm{sup 2}. Transmission electron microscopy indicated that while the overall crystallinity of these films remained essentially unaffected, the local microstructure of the materials was tremendously altered due to heavy ion irradiation, which implied that the melting and recrystallization process have occurred along the trajectory of the heavy ions. Such a process induced the formation of interconnected nanocluster networks, facilitating the electron conduction and enhancing the EFE properties for the materials. The enhancement in the EFE is more prominent for MCD films than that for UNCD films, reaching a low turn-on field of E{sub 0}=3.2 V/mum and large EFE current density of J{sub e}=3.04 mA/cm{sup 2} for 5x10{sup 11} ions/cm{sup 2} heavy ion irradiated samples.

  18. Secondary absorbed doses from light ion irradiation in anthropomorphic phantoms representing an adult male and a 10 year old child

    NASA Astrophysics Data System (ADS)

    Hultqvist, Martha; Gudowska, Irena

    2010-11-01

    Secondary organ absorbed doses were calculated by Monte Carlo simulations with the SHIELD-HIT07 code coupled with the mathematical anthropomorphic phantoms CHILD-HIT and ADAM-HIT. The simulated irradiations were performed with primary 1H, 4He, 7Li, 12C and 16O ion beams in the energy range 100-400 MeV/u which were directly impinging on the phantoms, i.e. approximating scanned beams, and with a simplified beamline for 12C irradiation. The evaluated absorbed doses to the out-of-field organs were in the range 10-6 to 10-1 mGy per target Gy and with standard deviations 0.5-20%. While the contribution to the organ absorbed doses from secondary neutrons dominated in the ion beams of low atomic number Z, the produced charged fragments and their subsequent charged secondaries of higher generations became increasingly important for the secondary dose delivery as Z of the primary ions increased. As compared to the simulated scanned 12C ion beam, the implementation of a simplified beamline for prostate irradiation with 12C ions resulted in an increase of 2-50 times in the organ absorbed doses depending on the distance from the target volume. Comparison of secondary organ absorbed doses delivered by 1H and 12C beams showed smaller differences when the RBE for local tumor control of the ions was considered and normalization to the RBE-weighted dose to the target was performed.

  19. Impact of heavy ion irradiation on CMOS current mirrors based on SOI and bulk Si substrates: mismatch and output impedance

    NASA Astrophysics Data System (ADS)

    Wu, Weikang; An, Xia; Tan, Fei; Chen, Yehua; Liu, Jingjing; Zhang, Yao; Zhang, Xing; Shen, Dongjun; Guo, Gang; Huang, Ru

    2015-11-01

    The impact of a single event on the performance of CMOS current mirrors (CMs) is studied experimentally in this paper. Both basic and cascode CMs based on bulk Si and PDSOI substrates are employed to demonstrate the permanent effects of damage generated by heavy-ion strikes. The results show that the mismatch of the CMs (bulk Si/PDSOI basic/cascode CMs) changes after heavy-ion irradiation, which means that the accuracy of the output current may need re-evaluation when CMs are operated in a harsh environment. For output impedance, a drastic reduction of 40% is observed for small (W/L = 0.5 ?m/0.25 ?m) PDSOI basic CMs. This may limit the application of CMs when high output impedance is required to provide a large gain or common mode rejection ratio. Different types of performance degradation after heavy-ion irradiation are classified, and the characteristics are also statistically compared between different types of CM. The mechanisms of these changes are then discussed and traced back to the damage induced by the random heavy-ion strikes. These results demonstrate the permanent effects of damage generated by heavy-ion strikes in CMOS CMs, and provide insights into the impact of heavy-ion irradiation on analog circuits.

  20. Studies of endothelial monolayer formation on irradiated poly-L-lactide acid with ions of different stopping power and velocity

    NASA Astrophysics Data System (ADS)

    Arbeitman, Claudia R.; del Grosso, Mariela F.; Ibañez, Irene L.; Behar, Moni; Grasselli, Mariano; Bermúdez, Gerardo García

    2015-12-01

    In this work we study cell viability, proliferation and morphology of bovine aortic endothelial cells (BAEC) cultured on poly-L-lactide acid (PLLA) modified by heavy ion irradiation. In a previous study comparing ions beams with the same stopping power we observed an increase in cell density and a better cell morphology at higher ion velocities. In the present work we continued this study using heavy ions beam with different stopping power and ion velocities. To this end thin films of 50 ?m thickness were irradiated with 2 MeV/u and 0.10 MeV/u ion beams provided the Tandar (Buenos Aires, Argentina) and Tandetron (Porto Alegre, Brazil) accelerators, respectively. The results suggest that a more dense and elongated cell shapes, similar to the BAEC cells on the internal surface of bovine aorta, was obtained for stopping power of 18.2-22.1 MeV cm2 mg-1 and ion velocity of 2 MeV/u. On the other hand, for low ion velocity 0.10 MeV/u the cells present a more globular shapes.

  1. Role of carbon impurities on the surface morphology evolution of tungsten under high dose helium ion irradiation

    NASA Astrophysics Data System (ADS)

    Al-Ajlony, A.; Tripathi, J. K.; Hassanein, A.

    2015-11-01

    The effect of carbon impurities on the surface evolution (e.g., fuzz formation) of tungsten (W) surface during 300 eV He ions irradiation was studied. Several tungsten samples were irradiated by He ion beam with a various carbon ions percentage. The presence of minute carbon contamination within the He ion beam was found to be effective in preventing the fuzz formation. At higher carbon concentration, the W surface was found to be fully covered with a thick graphitic layer on the top of tungsten carbide (WC) layer that cover the sample surface. Lowering the ion beam carbon percentage was effective in a significant reduction in the thickness of the surface graphite layer. Under these conditions the W surface was also found to be immune for the fuzz formation. The effect of W fuzz prevention by the WC formation on the sample surface was more noticeable when the He ion beam had much lower carbon (C) ions content (0.01% C). In this case, the fuzz formation was prevented on the vast majority of the W sample surface, while W fuzz was found in limited and isolated areas. The W surface also shows good resistance to morphology evolution when bombarded by high flux of pure H ions at 900 °C.

  2. Cutting and controlled modification of graphene with ion beams.

    PubMed

    Lehtinen, O; Kotakoski, J; Krasheninnikov, A V; Keinonen, J

    2011-04-29

    Using atomistic computer simulations, we study how ion irradiation can be used to alter the morphology of a graphene monolayer, by introducing defects of specific type, and to cut graphene sheets. Based on the results of our analytical potential molecular dynamics simulations, a kinetic Monte Carlo code is developed for modeling morphological changes in a graphene monolayer under irradiation at macroscopic time scales. Impacts of He, Ne, Ar, Kr, Xe, and Ga ions with kinetic energies ranging from tens of eV to 10 MeV and angles of incidence between 0° and 88° are studied. Our results provide microscopic insights into the response of graphene to ion irradiation and can directly be used for the optimization of graphene cutting and patterning with focused ion beams. PMID:21411912

  3. Chemical surface modification on polytetrafluoroethylene films by vacuum ultraviolet excimer lamp irradiation in ammonia gas atmosphere

    NASA Astrophysics Data System (ADS)

    Heitz, J.; Niino, H.; Yabe, A.

    1996-05-01

    Irradiation of polytetrafluoroethylene films with vacuum UV light in an ammonia gas atmosphere resulted in a hydrophilic surface, where abstraction of fluorine atoms, and introduction of nitrogen, oxygen, and hydrogen atoms occurred. We used Kr2* and Xe2* excimer lamps at wavelength of 146 and 172 nm, respectively. The reaction mechanism for chemical surface modification is discussed on the basis of x-ray photoelectron spectroscopy, secondary ion mass spectroscopy, and attenuated total reflection Fourier transform infrared spectroscopy analyses.

  4. Carbon-Ion Beam Irradiation Effectively Suppresses Migration and Invasion of Human Non-Small-Cell Lung Cancer Cells

    SciTech Connect

    Akino, Yuichi; Teshima, Teruki Kihara, Ayaka; Kodera-Suzumoto, Yuko; Inaoka, Miho; Higashiyama, Shigeki; Furusawa, Yoshiya; Matsuura, Nariaki

    2009-10-01

    Purpose: Control of cancer metastasis is one of the most important issues in cancer treatment. We previously demonstrated that carbon particle irradiation suppresses the metastatic potential of cancer cells, and many studies have reported that photon irradiation promotes it. The purpose of this study was to investigate the effect of carbon beam on non-small-cell lung cancer (NSCLC) cell aggressiveness and gene expression. Methods and Materials: A549 (lung adenocarcinoma) and EBC-1 (lung squamous cell carcinoma) cells were treated with 290 MeV/nucleon carbon ion beam at the Heavy Ion Medical Accelerator in Chiba or with 4-MV X-ray at Osaka University. We tested proliferative, migratory, and invasive activities by cell proliferation assay, Boyden chamber assay, and Matrigel chemoinvasion assay, respectively. cDNA microarray and reverse transcription polymerase chain reaction were also performed to assess mRNA expression alteration. Results: X-irradiation increased cell proliferation of A549 cells at 0.5 Gy, whereas high-dose X-ray reduced migration and invasion of A549 cells. By contrast, carbon beam irradiation did not enhance proliferation, and it reduced the migration and invasion capabilities of both A549 and EBC-1 cells more effectively than did X-irradiation. Carbon beam irradiation induced alteration of various gene expression profiles differently from X-ray irradiation. mRNA expression of ANLN, a homologue of anillin, was suppressed to 60% levels of basal expression in carbon beam-irradiated A549 cells after 12 h. Conclusion: Carbon beam effectively suppresses the metastatic potential of A549 and EBC-1 cells. Carbon beam also has different effects on gene expressions, and downregulation of ANLN was induced only by carbon beam irradiation.

  5. Electronic and atomic kinetics in solids irradiated with free-electron lasers or swift-heavy ions

    NASA Astrophysics Data System (ADS)

    Medvedev, N.; Volkov, A. E.; Ziaja, B.

    2015-12-01

    In this brief review we discuss the transient processes in solids under irradiation with femtosecond X-ray free-electron-laser (FEL) pulses and swift-heavy ions (SHI). Both kinds of irradiation produce highly excited electrons in a target on extremely short timescales. Transfer of the excess electronic energy into the lattice may lead to observable target modifications such as phase transitions and damage formation. Transient kinetics of material excitation and relaxation under FEL or SHI irradiation are comparatively discussed. The same origin for the electronic and atomic relaxation in both cases is demonstrated. Differences in these kinetics introduced by the geometrical effects (?m-size of a laser spot vs nm-size of an ion track) and initial irradiation (photoabsorption vs an ion impact) are analyzed. The basic mechanisms of electron transport and electron-lattice coupling are addressed. Appropriate models and their limitations are presented. Possibilities of thermal and nonthermal melting of materials under FEL and SHI irradiation are discussed.

  6. Oxygen ion irradiation on AlGaN/GaN heterostructure grown on silicon substrate by MOCVD method

    NASA Astrophysics Data System (ADS)

    Ramesh, R.; Arivazhagan, P.; Balaji, M.; Asokan, K.; Baskar, K.

    2015-06-01

    In the present work, we have reported 100 MeV O7+ ion irradiation with 1×1012 and 5×1012 ions/cm2 fluence on AlGaN/GaN heterostructures grown on silicon substrate by Metal Organic Chemical Vapour Deposition (MOCVD). The Irradiated samples were characterized by High Resolution X-Ray Diffraction (HRXRD), Atomic Force Microscope (AFM) and Photoluminescence (PL). Crystalline quality has been analysed before and after irradiation using HRXRD. Different kinds of morphology are attributed to specific type of dislocations using the existing models available in the literature. A sharp band-edge emission in the as grown samples was observed at ˜3.4 eV in GaN and 3.82 for AlGaN. The band-edge absorption intensity reduced due to irradiation and these results have been discussed in view of the damage created by the incident ions. In general the effect of irradiation induced-damages were analysed as a function of material properties. A possible mechanism responsible for the observations has been discussed.

  7. Effect of electronic energy loss and irradiation temperature on color-center creation in LiF and NaCl crystals irradiated with swift heavy ions

    SciTech Connect

    Schwartz, K.; Trautmann, C.; Voss, K.-O.; Neumann, R.; Volkov, A. E.; Sorokin, M. V.; Lang, M.

    2008-07-01

    LiF and NaCl crystals were irradiated at 8 K and 300 K with various light and heavy ions (C, Ti, Ni, Kr, Sm, Au, Pb, and U) of kinetic energy between about 50 and 2600 MeV, providing electronic energy losses from 0.7 to 26.4 keV/nm. A cryostat installed at the beamline allowed in situ absorption spectroscopy and thermostimulated luminescence (TSL) measurements from 8 K upward. Creation of electron and hole color centers is analyzed as a function of irradiation temperature, fluence, and thermal and optical bleaching. Anion interstitials (I and H centers) were only observed in crystals irradiated at 8 K. These defects are unstable and disappear in the temperature range 10-100 K. For heavy ions (Au, U), the F-center accumulation efficiency at low fluences is larger at 8 K than at room temperature. The opposite effect is observed for light ions (C, Ti, Ni). The results are discussed within the frame of transient heating influencing separation or annealing of point defects.

  8. Enhanced sputter yields of ion irradiated Au nano particles: energy and size dependence

    NASA Astrophysics Data System (ADS)

    Holland-Moritz, Henry; Scheeler, Sebastian; Stanglmair, Christoph; Pacholski, Claudia; Ronning, Carsten

    2015-08-01

    Hexagonally arranged Au nanoparticles exhibiting a broad Gaussian-shaped size distribution ranging from 30 nm to 80 nm were deposited on Si substrates and irradiated with Ar+ and Ga+ ions with various energies from 20 to 350 keV and 1 to 30 keV, respectively. The size and energy dependence of the sputter yield were measured using high-resolution scanning electron microscopy image analysis. These results were compared to simulation results obtained by iradina, a Monte Carlo code, which takes the specifics of the nano geometry into account. The experimental sputter yields are significantly higher than simulated sputter yields for both bulk and the nano geometry. The difference can be clearly attributed to thermally driven effects, which significantly increase the measured sputter yields.

  9. A thousand-fold enhancement of photoluminescence in porous silicon using ion irradiation

    SciTech Connect

    Azimi, S.; Breese, M. B. H.; Singapore Synchrotron Light Source , National University of Singapore, 5 Research Link, Singapore 117603 ; Song, J.; Dang, Z. Y.

    2013-08-07

    A large increase in the porosity of highly doped p-type silicon is observed at the end-of-range depth of high-energy ions after subsequent electrochemical anodization. This occurs under certain conditions of irradiation geometry and fluence, owing to the dual effects of increased wafer resistivity and a locally increased current density during anodization. This results in the creation of highly porous, sub-surface zones which emit photoluminescence with an intensity of more than three orders of magnitude greater than the surrounding mesoporous silicon, comparable to that produced by microporous silicon. This provides means of selectively enhancing and patterning the photoluminescence emission from micron-sized areas of porous silicon over a wide range of intensity.

  10. Optimal conditions for high current proton irradiations at the university of Wisconsin's ion beam laboratory

    NASA Astrophysics Data System (ADS)

    Wetteland, C. J.; Field, K. G.; Eiden, T. J.; Gerczak, T. J.; Maier, B. R.; Albakri, O.; Sridharan, K.; Allen, T. R.

    2013-04-01

    The National Electrostatics Corporation's (NEC) Toroidal Volume Ion Source (TORVIS) source is known for exceptionally high proton currents with minimal service downtime as compared to traditional sputter sources. It has been possible to obtain over 150?A of proton current from the source, with over 70?A on the target stage. However, beam fluxes above ˜1×1017/m2-s may have many undesirable effects, especially for insulators. This may include high temperature gradients at the surface, sputtering, surface discharge, cracking or even disintegration of the sample. A series of experiments were conducted to examine the role of high current fluxes in a suite of ceramics and insulating materials. Results will show the optimal proton irradiation conditions and target mounting strategies needed to minimize unwanted macro-scale damage, while developing a procedure for conducting preliminary radiation experiments.

  11. Optimal conditions for high current proton irradiations at the university of Wisconsin's ion beam laboratory

    SciTech Connect

    Wetteland, C. J.; Field, K. G.; Gerczak, T. J.; Eiden, T. J.; Maier, B. R.; Albakri, O.; Sridharan, K.; Allen, T. R.

    2013-04-19

    The National Electrostatics Corporation's (NEC) Toroidal Volume Ion Source (TORVIS) source is known for exceptionally high proton currents with minimal service downtime as compared to traditional sputter sources. It has been possible to obtain over 150{mu}A of proton current from the source, with over 70{mu}A on the target stage. However, beam fluxes above {approx}1 Multiplication-Sign 10{sup 17}/m2-s may have many undesirable effects, especially for insulators. This may include high temperature gradients at the surface, sputtering, surface discharge, cracking or even disintegration of the sample. A series of experiments were conducted to examine the role of high current fluxes in a suite of ceramics and insulating materials. Results will show the optimal proton irradiation conditions and target mounting strategies needed to minimize unwanted macro-scale damage, while developing a procedure for conducting preliminary radiation experiments.

  12. Ion Irradiation Experiments on the Murchison CM2 Carbonaceous Chondrite: Simulating Space Weathering of Primitive Asteroids

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Christoffersen, R.; Dukes, C. A.; Baragiola, R. A.; Rahman, Z.

    2015-01-01

    Remote sensing observations show that space weathering processes affect all airless bodies in the Solar System to some degree. Sample analyses and lab experiments provide insights into the chemical, spectroscopic and mineralogic effects of space weathering and aid in the interpretation of remote- sensing data. For example, analyses of particles returned from the S-type asteroid Itokawa by the Hayabusa mission revealed that space-weathering on that body was dominated by interactions with the solar wind acting on LL ordinary chondrite-like materials [1, 2]. Understanding and predicting how the surface regoliths of primitive carbonaceous asteroids respond to space weathering processes is important for future sample return missions (Hayabusa 2 and OSIRIS-REx) that are targeting objects of this type. Here, we report the results of our preliminary ion irradiation experiments on a hydrated carbonaceous chondrite with emphasis on microstructural and infrared spectral changes.

  13. Magnetic properties of ultrathin CO/Pt multilayer Hall devices irradiated using focused ion beam

    NASA Astrophysics Data System (ADS)

    Wang, K.; Huang, Y.; Qiu, Y. Z.; Chen, R. F.; Heard, P.; Bending, S.

    2015-11-01

    A ferromagnetic Co/Pt multilayer was lithographically patterned into 10-?m-wide Hall devices. The anisotropy of the fabricated devices was modified using focused ion beam (FIB). Extraordinary Hall effect (EHE) measurements reveal pronounced reduction in nucleation field of the perpendicular loops at room temperature. At low temperature of 4.2 K reduced remanent ratios in EHE loops were observed, indicating a tilting of easy magnetic axis. The canting magnetization can be explained by an increasing magnetic moment at low temperatures and a reduced anisotropy by irradiation. The aperture angles were estimated to be in the range of 20-32° at 4.2 K. The aperture angle of the easy cone of magnetization was found to increase with doses at low temperatures.

  14. Coupling of morphology to surface transport in ion-beam irradiated surfaces: Oblique incidence Javier Muoz-Garca*

    E-print Network

    Cuerno, Rodolfo

    Coupling of morphology to surface transport in ion-beam irradiated surfaces: Oblique incidence Leganés, Spain Mario Castro GISC and Grupo de Dinámica No Lineal (DNL), Escuela Técnica Superior de energies and oblique incidence. After considering the current limitations of more standard descriptions

  15. Enhancement in anomalous Hall resistivity of Co/Pd multilayer and CoPd alloy by Ga+ ion irradiation

    NASA Astrophysics Data System (ADS)

    Guo, Z. B.; Mi, W. B.; Li, J. Q.; Cheng, Y. C.; Zhang, X. X.

    2014-02-01

    In this paper, we report the effect of Ga+ ion irradiation on anomalous Hall effect (AHE) and longitudinal resistivity (\\rho_{\\textit{xx}}) in [Co(3 Å)/Pd(5 Å)]80 multilayer and Co42Pd58 alloy. 4- and 2-fold increases in anomalous Hall resistivity (\\rho_{\\textit{AH}}) in the Co/Pd multilayer and CoPd alloy have been observed after irradiations at doses of 2.4\\times 10^{15} and 3.3\\times 10^{15}\\ \\text{ions/cm}^{2} , respectively. Skew scattering and side jump contributions to AHE have been analyzed based on the scaling relationship \\rho_{\\textit{AH}}=a\\rho_{\\textit{xx}}+b\\rho_{\\textit{xx}}^{2} . For the Co/Pd multilayer, AHE is mainly affected by ion irradiation-induced interface diffusion and defects. For the CoPd alloy, the increase in doses above 1.5\\times 10^{15}\\ \\text{ions/cm}^{2} induces a sign change in skew scattering, followed by the skew scattering contribution to AHE overwhelming the side jump contribution, this phenomenon should be attributed to irradiation-induced defects and modifications in chemical ordering.

  16. Xenon-ion-induced and thermal mixing of Co/Si bilayers and their interplay

    NASA Astrophysics Data System (ADS)

    Novakovi?, M.; Zhang, K.; Popovi?, M.; Bibi?, N.; Hofsäss, H.; Lieb, K. P.

    2011-05-01

    Studies on ion-irradiated transition-metal/silicon bilayers demonstrate that interface mixing and silicide phase formation depend sensitively on the ion and film parameters, including the structure of the metal/Si interface. Thin Co layers e-gun evaporated to a thickness of 50 nm on Si(1 0 0) wafers were bombarded at room temperature with 400-keV Xe + ions at fluences of up to 3 × 10 16 cm -2. We used either crystalline or pre-amorphized Si wafers the latter ones prepared by 1.0-keV Ar-ion implantation. The as-deposited or Xe-ion-irradiated samples were then isochronally annealed at temperatures up to 700 °C. Changes of the bilayer structures induced by ion irradiation and/or annealing were investigated with RBS, XRD and HRTEM. The mixing rate for the Co/c-Si couples, ? ?2/ ? = 3.0(4) nm 4, is higher than the value expected for ballistic mixing and about half the value typical for spike mixing. Mixing of pre-amorphized Si is much weaker relative to crystalline Si wafers, contrary to previous results obtained for Fe/Si bilayers. Annealing of irradiated samples produces very similar interdiffusion and phase formation patterns above 400 °C as in the non-irradiated Co/Si bilayers: the phase evolution follows the sequence Co 2Si ? CoSi ? CoSi 2.

  17. Microstructure changes and thermal conductivity reduction in UO2 following 3.9 MeV He2+ ion irradiation

    SciTech Connect

    Janne Pakrinen; Marat Khafizov; Lingfeng He; Chris Wetland; Jian Gan; Andrew T. Nelson; David H Hurley; Anter El-Azab; Todd R Allen

    2014-11-01

    The microstructural changes and associated effects on thermal conductivity were examined in UO2 after irradiation using 3.9 MeV He2+ ions. Lattice expansion of UO2 was observed in x-ray diffraction after ion irradiation up to 5×1016 He2+/cm2 at low-temperature (< 200 °C). Transmission electron microscopy (TEM) showed homogenous irradiation damage across an 8 µm thick plateau region, which consisted of small dislocation loops accompanied by dislocation segments. Dome-shaped blisters were observed at the peak damage region (depth around 8.5 µm) in the sample subjected to 5×1016 He2+/cm2, the highest fluence reached, while similar features were not detected at 9×1015 He2+/cm2. Laser-based thermo-reflectance measurements showed that the thermal conductivity for the irradiated layer decreased about 55 % for the high fluence sample and 35% for the low fluence sample as compared to an un-irradiated reference sample. Detailed analysis for the thermal conductivity indicated that the conductivity reduction was caused by the irradiation induced point defects.

  18. Transmission electron microscopy of the amorphization of copper indium diselenide by in situ ion irradiation

    SciTech Connect

    Hinks, J. A.; Edmondson, P. D.

    2012-03-01

    Copper indium diselenide (CIS), along with its derivatives Cu(In,Ga)(Se,S){sub 2}, is a prime candidate for use in the absorber layers of photovoltaic devices. Due to its ability to resist radiation damage, it is particularly well suited for use in extraterrestrial and other irradiating environments. However, the nature of its radiation hardness is not well understood. In this study, transmission electron microscopy (TEM) with in situ ion irradiation was used to monitor the dynamic microstructural effects of radiation damage on CIS. Samples were bombarded with 400 keV xenon ions to create large numbers of atomic displacements within the thickness of the TEM samples and thus explore the conditions under which, if any, CIS could be amorphized. By observing the impact of heavily damaging radiation in situ--rather than merely the end-state possible in ex situ experiments--at the magnifications allowed by TEM, it was possible to gain an understanding of the atomistic processes at work and the underlying mechanism that give rise to the radiation hardness of CIS. At 200 K and below, it was found that copper-poor samples could be amorphized and copper-rich samples could not. This difference in behavior is linked to the crystallographic phases that are present at different compositions. Amorphization was found to progress via a combination of one- and two-hit processes. The radiation hardness of CIS is discussed in terms of crystallographic structures/defects and the consequences these have for the ability of the material to recover from the effects of displacing radiation.

  19. Characterization of Treefoil Peptide Genes in Iron-Ion or X-Irradiated Human Cells

    NASA Technical Reports Server (NTRS)

    Balcer-Kubiczek, E. K.; Harrison, G. H.; Xu, J. F.; Zhou, X. F.

    1999-01-01

    The gastrointestinal (GI) tract is especially sensitive to ionizing radiation, probably because of its high rate of cell turn over. Most of the data in the literature concerns the histological/anatomical description of damage rather than functional studies. In fact, previous reports in humans have shown that, at doses of 2 Gy or more, functional abnormalities appear indicating that in radiation sensitive tissues the effects of radiation are not limited to cell death. GI functions are controlled in particular by GI peptides. One hypothesis is that ionizing radiation may modulate the synthesis and release of these peptides and consequently may contribute largely to abnormalities in GI function. However, no previous studies have been concerned with GI-specific gene expression in irradiated GI tissues. The family of human trefoil peptides comprises three members thus far, all of which are expressed in specific regions of the GI tract. In addition, two trefoil peptides, pS2 (TFFI) and HITF (TFF2) are expressed in breast tissue. Their exact function in GI and breast tissues is unclear but mucosal integrity, repair, mucin secretion and responsiveness to hormones have been shown. We recently isolated and characterized pS2 as a novel p53- and estrogen receptor-independent gene whose MRNA expression in several cells lines was found to be delayed 4 to 7 days after irradiation with X-rays, fission neutrons or 1 GeV/n Fe-ions. The aim of the present study was to determine whether pS2 and HITF have a similar induction kinetics in irradiated gastric and breast cell lines, and whether they have the phorbol ester (TPA) responsive element (TRE).

  20. The 2140/cm band of frozen CO in ion-irradiated and unirradiated mixtures with methanol and water

    NASA Astrophysics Data System (ADS)

    Palumbo, M. E.; Strazzulla, G.

    1992-06-01

    We present laboratory data on the shape of the 4.67 micron band of frozen CO in mixtures with CH3OH and CH3OH+H2O. The mixtures have been produced both by depositing CO together with CH3OH (or CH3OH+H2O) and by depositing only CH3OH CH3OH+H2O) and producing CO by ion irradiation. We find that the mixtures here studied are good candidates to reproduce the band observed in astronomical sources. The effect of producing CO by ion irradiation is that the band results to be broader. The same is observed for the narrow band of irradiated pure CO. Such a broadening might help, under circumstances to be investigated in detail, to better reproduce the astronomical spectra.

  1. Experimental evidence of crystalline hillocks created by irradiation of CeO2 with swift heavy ions: TEM study

    NASA Astrophysics Data System (ADS)

    Ishikawa, N.; Okubo, N.; Taguchi, T.

    2015-09-01

    In this study, CeO2 was irradiated with 200 MeV Au ions at oblique incidence. Observation of as-irradiated samples by transmission electron microscopy (TEM) shows that hillocks are created not only at the wide surfaces, but also at the crack faces of the thin samples. Since the hillocks created at the crack faces can be imaged by TEM, their shape and crystallographic features can be revealed. From the images of hillocks created at the crack faces, many of the hillocks are found to be spherical. We present the first experimental evidence that hillocks created for CeO2 irradiated with swift heavy ions have a crystal structure whose lattice spacing and orientation coincide with those of the matrix. The mechanism of spherical crystalline hillock formation is discussed based on the present results.

  2. Experimental evidence of crystalline hillocks created by irradiation of CeO? with swift heavy ions: TEM study.

    PubMed

    Ishikawa, N; Okubo, N; Taguchi, T

    2015-09-01

    In this study, CeO2 was irradiated with 200 MeV Au ions at oblique incidence. Observation of as-irradiated samples by transmission electron microscopy (TEM) shows that hillocks are created not only at the wide surfaces, but also at the crack faces of the thin samples. Since the hillocks created at the crack faces can be imaged by TEM, their shape and crystallographic features can be revealed. From the images of hillocks created at the crack faces, many of the hillocks are found to be spherical. We present the first experimental evidence that hillocks created for CeO2 irradiated with swift heavy ions have a crystal structure whose lattice spacing and orientation coincide with those of the matrix. The mechanism of spherical crystalline hillock formation is discussed based on the present results. PMID:26245538

  3. Fraxinus paxiana bark mediated photosynthesis of silver nanoparticles and their size modulation using swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Sharma, Hemant; Vendamani, V. S.; Pathak, Anand P.; Tiwari, Archana

    2015-12-01

    Photosynthesis of silver nanoparticles is presented using bark extracts of Fraxinus paxiana var. sikkimensis. The synthesized nanoparticles are characterised by UV-Vis absorption, photoluminescence, powder X-ray diffraction and scanning and transmission electron microscopy. In addition, the bark samples are irradiated with 100 MeV silver ions and the subsequent structural modifications are analyzed. The swift heavy ion irradiated Fraxinus paxiana var. sikkimensis bark is also used for the synthesis of silver nanoparticles. It is illustrated that the irradiated bark assists in synthesizing smaller nanoparticles of homogenous size distribution as compared to when the pristine bark is used. The newly synthesized silver nanoparticles are also used to demonstrate the antimicrobial activities on Escherichia coli bacteria.

  4. Influence of ion irradiation on the resistive switching parameters of SiOx-based thin-film structures

    NASA Astrophysics Data System (ADS)

    Korolev, D. S.; Mikhaylov, A. N.; Belov, A. I.; Sergeev, V. A.; Antonov, I. N.; Kasatkin, A. P.; Gorshkov, O. N.; Tetelbaum, D. I.

    2015-11-01

    For the memristive Au/SiOx/TiN/Ti structures produced by magnetron sputtering and demonstrating reproducible bipolar resistive switching, the dependence of resistive states on the dose of irradiation with H+ and Ne+ ions with energy of 150 keV has been established. It is shown that, under proton irradiation, the resistive switching is not deteriorated up to the dose of 1.1016 cm-2, and, in the case of Ne+ irradiation – up to the dose of 3.31015 cm-2 (equivalent by the ionization losses). As the Ne+ ions produce three orders of magnitude more elastic collisions than protons (for the same dose), the obtained results allow to predict the high radiation tolerance of the memristive structures to both ionization and displacement damage.

  5. In situ TEM study of G-phase precipitates under heavy ion irradiation in CF8 cast austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Ying; Li, Meimei; Zhang, Xuan; Kirk, Marquis A.; Baldo, Peter M.; Lian, Tiangan

    2015-09-01

    Thermally-aged cast austenitic stainless steels (CASS) CF8 was irradiated with 1 MeV Kr ions at 300, 350 and 400 °C to 1.88 × 1019 ions/m2 (?3 dpa) at the IVEM-Tandem Facility at the Argonne National Laboratory. Before irradiation, the distribution of G-phase precipitates in the ferrite showed spatial variations, and both their size and density were affected by the ferrite-austenite phase boundary and presence of M23C6 carbides. Under 300 °C irradiation, in situ TEM observation showed G-phase precipitates were relatively unchanged in the vicinity of the phase boundary M23C6 carbides, while the density of G-phase precipitates increased with increasing dose within the ferrite matrix. Coarsening of G-phase precipitates was observed in the vicinity of phase boundary M23C6 carbides at 350 °C and 400 °C.

  6. Modification of Pt/Co/Pt film properties by ion irradiation

    NASA Astrophysics Data System (ADS)

    Avchaciov, K. A.; Ren, W.; Djurabekova, F.; Nordlund, K.; Sveklo, I.; Maziewski, A.

    2015-09-01

    We studied the structural modifications of a Pt/Co/Pt trilayer epitaxial film under Ga+ 30-keV ion irradiation by means of classical molecular dynamics and Monte Carlo simulations. The semiclassical tight-binding second-moment approximation potential was adjusted to reproduce the enthalpies of formation, the lattice constants, and the order-disorder transition temperatures for Co-Pt alloys. We found that during irradiation, the sandwich-type Pt(fcc)/Co(hcp)/Pt(fcc) film structure underwent a transition to the new solid solution ? -Co /Pt (fcc ) phase. Our analysis of the short-range order indicates the formation, within a nanosecond time scale, of a homogeneous chemically disordered solution. The longer time-scale simulations employing a Monte Carlo algorithm demonstrated that the transition from the disordered phase to the ordered L 10 and L 12 phases was also possible but not significant for the changes in perpendicular magnetic anisotropy (PMA) observed experimentally. The strain analysis showed that the Co layer was under tensile strain in the lateral direction at the fluences of 1.5 ×1014-3.5 ×1014ionscm -2 ; this range of fluences corresponds to the appearance of PMA. This strain was induced in the initially relaxed hcp Co layer due to its partial transformation to the fcc phase and to the influence of atomic layers with larger lattice constants at upper/lower interfaces.

  7. Radiation stability of ceramic waste forms determined by in situ electron microscopy and He ion irradiation

    SciTech Connect

    White, T.J.; Mitamura, H.; Hojou, K.; Furuno, S.

    1994-12-31

    The radiation stability of polyphase titanate ceramic waste forms was studied using analytical transmission electron microscopy, in combination with in situ irradiation by 30 keV He{sup +} ions, followed by staged annealing. Two experiments were conducted. In the first, a reconnaissance investigation was made of the stabilities of the synthetic minerals hollandite, zirconolite, and perovskite when subjected to a total dose of 1.8 x 10{sup 17} He{sup +} cm{sup {minus}2}. It was found that all phases amorphized at approximately the same rate, but perovskite recovered its structure more rapidly and at lower temperatures than the other phases. In particular, annealing for 10 minutes at 1000{degrees}C was sufficient for perovskite to completely regain its crystallinity, while zirconolite and hollandite were only partially restored by these conditions. In the second experiment, the response of a thin hollandite crystal to irradiation was examined by selected area electron diffraction. At a dose of 1.5 x 10{sup 15} He{sup +} cm{sup {minus}2} its incommensurate superstructure was disrupted, but even at a dose of 3 x 10{sup 16} He cm{sup {minus}2} the hollandite subcell was largely intact. For this dose, total recovery was achieved by annealing for 1 minute at 1000{degrees}C.

  8. Effects of radical scavengers on aqueous solutions exposed to heavy-ion irradiation using the liquid microjet technique

    NASA Astrophysics Data System (ADS)

    Nomura, Shinji; Tsuchida, Hidetsugu; Furuya, Ryousuke; Miyahara, Kento; Majima, Takuya; Itoh, Akio

    2015-12-01

    The effects of the radical scavenger ascorbic acid on water radiolysis are studied by fast heavy-ion irradiation of aqueous solutions of ascorbic acid, using the liquid microjet technique under vacuum. To understand the reaction mechanisms of hydroxyl radicals in aqueous solutions, we directly measure secondary ions emitted from solutions with different ascorbic acid concentrations. The yield of hydronium secondary ions is strongly influenced by the reaction between ascorbic acid and hydroxyl radicals. From analysis using a simple model considering chemical equilibria, we determine that the upper concentration limit of ascorbic acid with a radical scavenger effect is approximately 70 ?M.

  9. Involvement of DNA-PK(sub cs) in DSB Repair Following Fe-56 Ion Irradiation

    NASA Technical Reports Server (NTRS)

    O'Neill, Peter; Harper, Jane; Anderson, Jennifer a.; Cucinnota, Francis A.

    2007-01-01

    When cells are exposed to radiation, cellular lesions are induced in the DNA including double strand breaks (DSBs), single strand breaks and clustered DNA damage, which if not repaired with high fidelity may lead to detrimental biological consequences. Complex DSBs are induced by ionizing radiation and characterized by the presence of base lesions close to the break termini. They are believed to be one of the major causes of the biological effects of IR. The complexity of DSBs increases with the ionization density of the radiation and these complex DSBs are distinct from the damage induced by sparsely ionizing gamma-radiation. It has been hypothesized that complex DSBs produced by heavy ions in space pose problems to the DNA repair machinery. We have used imm uno-cyto-chemical staining of phosphorylated histone H2AX (gamma-H2AX) foci, as a marker of DSBs. We have investigated the formation and loss of gamma-H2AX foci and RAD51 foci (a protein involved in the homologous recombination pathway) in mammalian cells induced by low fluences of low-LET gamma-radiation and high-LET Fe-56 ions (1GeV/n, 151 keV/micron LET). M059J and M059K cells, which are deficient and proficient in DNA-PK(sub cs) activity respectively, were used to examine the role of DNA-PK(sub cs), a key protein in the non-homologous end joining (NHEJ) pathway of DSB repair, along with HF19 human fibroblasts. Followi ng irradiation with Fe-56 ions the rate of repair was slower in M059J cells compared with that in M059K, indicating a role for DNA-PK(sub cs) in the repair of DSB induced by Fe-56 ions. However a small percentage of DSBs induced are rejoined within 5 h although many DSBs still persist up to 24 h. When RAD51 was examined in M059J/K cells, RAD51 foci are visible 24 hours after irradiation in approximately 40% of M059J cells compared with <5% of M059K cells indicating that persistent DSBs or those formed at stalled replication forks recruit RAD51 in DNA-PK(sub cs) deficient cells. Following 1 Gy gamma-radiation the induction of gamma-H2AX foci is similar in M059J and M059K cells. However, the repair rate of DSBs is slower in M059J cells than in M059K as shown previously but faster than seen with DSB induced by 56Fe ions. Vanillin, an inhibitor of DNA-PK(sub cs), reduces significantly the rate of DSB repair in HF19 cells following 1 Gy gamma-radiation but at 0.25 Gy gamma-irradiation the rate of DSB repair is similar in the presence or absence vanillin, thus suggesting the repair of a sub-set of DSBs induced by low dose, low-LET radiation does not require DNA-PK(sub cs). This sub-set of DSBs is formed in lower yield with high LET radiation. T he complexity of DNA DSBs induced by HZE radiation will be discussed in terms of reduced repair efficiency and provide scope to model different sub-classes of DSBs as precursors that may lead to the detrimental health effects of HZE radiation.

  10. Low-dose carbon ion irradiation effects on DNA damage and oxidative stress in the mouse testis

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Long, Jing; Zhang, Luwei; Zhang, Hong; Liu, Bin; Zhao, Weiping; Wu, Zhehua

    2011-01-01

    To investigate the effects of low-dose carbon ion irradiation on reproductive system of mice, the testes of outbred Kunming strain mice were whole-body irradiated with 0, 0.05, 0.1, 0.5 and 1 Gy, respectively. We measured DNA double-strand breaks (DNA DSBs) and oxidative stress parameters including malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, and testis weight and sperm count at 12 h, 21 d and 35 d after irradiation in mouse testis. At 12 h postirradiation, a significant increase in DNA DSB level but no pronounced alterations in MDA content or SOD activity were observed in 0.5 and 1 Gy groups compared with the control group. At 21 d postirradiation, there was a significant reduction in sperm count and distinct enhancements of DSB level and MDA content in 0.5 and 1 Gy groups in comparison with control. At 35 d postirradiation, the levels of DNA DSBs and MDA, and SOD activity returned to the baseline except for the MDA content in 1 Gy (P < 0.05), while extreme falls of sperm count were still observed in 0.5 (P < 0.01) and 1 Gy (P < 0.01) groups. For the 0.05 or 0.1 Gy group, no differences were found in DNA DSB level and MDA content between control and at 12 h, 21 d and 35 d after irradiation, indicating that lower doses of carbon ion irradiation have no significant influence on spermatogenesis processes. In this study, male germ cells irradiated with over 0.5 Gy of carbon ions are difficult to repair completely marked by the sperm count. Furthermore, these data suggest that the deleterious effects may be chronic or delayed in reproductive system after whole-body exposure to acute high-dose carbon ions.

  11. Effect of heavy ion irradiation on self-assembled Pr3+:ZnS/TiO2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Sana, Prabha; Verma, Shammi; Malik, M. M.

    2014-03-01

    We report the modifications in the structural and optical characteristics of Pr doped ZnS/TiO2 nanocrystals under 120 MeV Au9+ ions irradiation at various fluence ranges. The structural modification of Pr doped ZnS/TiO2 under swift heavy ion irradiation (SHI) shows texturing of ZnS crystalline planes as revealed by x-ray diffraction (XRD) pattern. Scanning electron microscopy (SEM) analysis shows cubical microstructures of pristine Pr3+ doped ZnS/TiO2 which are grown by aggregated nanoparticles. The morphological modifications under SHI show the growth of nano whiskers at highest fluence 3 × 1013 ions cm-2 with simultaneous disintegration of the initial cubical morphology. Photoluminescence (PL) spectrum reveals the white emission with luminescence peak at 485 nm, 525 nm and 665 nm for corresponding transition energy levels 3P0- 3H4, 3P0- 3H5 and 3P0- 3F2 of Pr3+ ions in ZnS host matrix. Also, it shows the characteristic blue emission due to sulphur vacancies at 379 nm in ZnS. At higher irradiation fluence 3 × 1013 ions cm-2, decreased PL intensity shows production of high dislocation density or non-radiative recombination of carriers in nanocrystalline Pr3+ doped ZnS/TiO2 structure.

  12. In situ studies of ion irradiated inverse spinel compound magnesium stannate (Mg 2SnO 4)

    NASA Astrophysics Data System (ADS)

    Xu, P.; Tang, M.; Nino, J. C.

    2009-06-01

    Magnesium stannate spinel (Mg 2SnO 4) was synthesized through conventional solid state processing and then irradiated with 1.0 MeV Kr 2+ ions at low temperatures 50 and 150 K. Structural evolutions during irradiation were monitored and recorded through bright field images and selected-area electron diffraction patterns using in situ transmission electron microscopy. The amorphization of Mg 2SnO 4 was achieved at an ion dose of 5 × 10 19 Kr ions/m 2 at 50 K and 10 20 Kr ions/m 2 at 150 K, which is equivalent to an atomic displacement damage of 5.5 and 11.0 dpa, respectively. The spinel crystal structure was thermally recovered at room temperature from the amorphous phase caused by irradiation at 50 K. The calculated electronic and nuclear stopping powers suggest that the radiation damage caused by 1 MeV Kr 2+ ions in Mg 2SnO 4 is mainly due to atomic displacement induced defect accumulation. The radiation tolerance of Mg 2SnO 4 was finally compared with normal spinel MgAl 2O 4.

  13. Influence of heavy ion irradiation on DC and gate-lag performance of AlGaN/GaN HEMTs

    NASA Astrophysics Data System (ADS)

    Lei, Zhi-Feng; Guo, Hong-Xia; Zeng, Chang; Chen, Hui; Wang, Yuan-Sheng; Zhang, Zhan-Gang

    2015-05-01

    AlGaN/GaN high electron mobility transistors (HEMTs) were irradiated by 256 MeV 127I ions with a fluence up to 1×1010 ions/cm2 at the HI-13 heavy ion accelerator of the China Institute of Atomic Energy. Both the drain current Id and the gate current Ig increased in off-state during irradiation. Post-irradiation measurement results show that the device output, transfer, and gate characteristics changed significantly. The saturation drain current, reverse gate leakage current, and the gate-lag all increased dramatically. By photo emission microscopy, electroluminescence hot spots were found in the gate area. All of the parameters were retested after one day and after one week, and no obvious annealing effect was observed under a temperature of 300 K. Further analysis demonstrates that swift heavy ions produced latent tracks along the ion trajectories through the hetero-junction. Radiation-induced defects in the latent tracks decreased the charges in the two-dimensional electron gas and reduced the carrier mobility, degrading device performance. Project supported by the National Natural Science Foundation of China (Grant No. 61204112).

  14. Local ion irradiation-induced resistive threshold and memory switching in Nb2O5/NbO(x) films.

    PubMed

    Wylezich, Helge; Mähne, Hannes; Rensberg, Jura; Ronning, Carsten; Zahn, Peter; Slesazeck, Stefan; Mikolajick, Thomas

    2014-10-22

    Resistive switching devices with a Nb2O5/NbOx bilayer stack combine threshold and memory switching. Here we present a new fabrication method to form such devices. Amorphous Nb2O5 layers were treated by a krypton irradiation. Two effects are found to turn the oxide partly into a metallic NbOx layer: preferential sputtering and interface mixing. Both effects take place at different locations in the material stack of the device; preferential sputtering affects the surface, while interface mixing appears at the bottom electrode. To separate both effects, devices were irradiated at different energies (4, 10, and 35 keV). Structural changes caused by ion irradiation are studied in detail. After successful electroforming, the devices exhibit the desired threshold switching. In addition, the choice of the current compliance defines whether a memory effect adds to the device. Findings from electrical characterization disclose a model of the layer modification during irradiation. PMID:25212179

  15. Extended calibration range for prompt photon emission in ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Bellini, F.; Boehlen, T. T.; Chin, M. P. W.; Collamati, F.; De Lucia, E.; Faccini, R.; Ferrari, A.; Lanza, L.; Mancini-Terracciano, C.; Marafini, M.; Mattei, I.; Morganti, S.; Ortega, P. G.; Patera, V.; Piersanti, L.; Russomando, A.; Sala, P. R.; Sarti, A.; Sciubba, A.; Solfaroli Camillocci, E.; Voena, C.

    2014-05-01

    Monitoring the dose delivered during proton and carbon ion therapy is still a matter of research. Among the possible solutions, several exploit the measurement of the single photon emission from nuclear decays induced by the irradiation. To fully characterize such emission the detectors need development, since the energy spectrum spans the range above the MeV that is not traditionally used in medical applications. On the other hand, a deeper understanding of the reactions involving gamma production is needed in order to improve the physic models of Monte Carlo codes, relevant for an accurate prediction of the prompt-gamma energy spectrum. This paper describes a calibration technique tailored for the range of energy of interest and reanalyzes the data of the interaction of a 80 MeV/u fully stripped carbon ion beam with a Poly-methyl methacrylate target. By adopting the FLUKA simulation with the appropriate calibration and resolution a significant improvement in the agreement between data and simulation is reported.

  16. Real-time single-ion hit position detecting system for cell irradiation

    NASA Astrophysics Data System (ADS)

    Satoh, Takahiro; Koka, Masahi; Kada, Wataru; Yokoyama, Akihito; Kamiya, Tomihiro

    2014-08-01

    We have developed a real-time single-ion hit position detecting system to replace a CR-39 solid-state nuclear-track detector for cell irradiation experiments because the CR-39 takes several minutes for off-line etching. The new real-time system consists of a 500-?m-thick CaF2(Eu) scintillator, an optical microscope with a 10× objective lens, and a high-gain charge-coupled device camera. Each of the 260-MeV neon ions passing through a 100-?m-thick CR-39 sheet was detected using the real-time system in a performance test for the spatial resolution. The full width at half maxima (FWHMs) of the distances between positions detected by the real-time system and the centers of the etch pits on CR-39 were 6.5 and 6.9 ?m in the x and y directions, respectively. The result shows that the system is useful for typical cultured cells of a few tens of micrometers in size.

  17. Microstructure of RERTR Du-Alloys Irradiated with Krypton Ions up to 100 dpa

    SciTech Connect

    J. Gan; D. D. Keiser, Jr.; D. M. Wachs; B. D. Miller; T. R. Allen; M. Kirk; J. Rest

    2011-04-01

    The radiation stability of the interaction product formed at the fuel–matrix interface of research reactor dispersion fuels, under fission-product bombardment, has a strong impact on fuel performance. Three depleted uranium alloys were cast that consisted of the following five phases to be investigated: U(Si, Al)3, (U, Mo)(Si, Al)3, UMo2Al20, U6Mo4Al43, and UAl4. Irradiation of transmission electron microscopy (TEM) disc samples with 500-keV Kr ions at 200 °C to doses up to 100 displacements per atom (dpa) were conducted using a 300-keV electron microscope equipped with an ion accelerator. TEM results show that the U(Si, Al)3 and UAl4 phases remain crystalline at 100 dpa without forming voids. The (U, Mo)(Si, Al)3 and UMo2Al20 phases become amorphous at 1 and 2 dpa, respectively, and show no evidence of voids at 100 dpa. The U6Mo4Al43 phase goes to amorphous at less than 1 dpa and reveals high density voids at 100 dpa.

  18. Microstructural evolution of nanocrystalline nickel thin films due to high-energy heavy-ion irradiation

    SciTech Connect

    Rajasekhara, S.; Ferreira, P. J.; Hattar, K.

    2013-04-19

    This initial feasibility study demonstrates that recent advancements in precession electron diffraction microscopy can be applied to nanostructured metals exposed to high displacement damage from a Tandem accelerator. In this study, high purity, nanocrystalline, free-standing nickel thin films produced by pulsed laser deposition were irradiated with approximately 3 Multiplication-Sign 10{sup 14} ions/cm{sup 2} of 35 MeV Ni{sup 6+} ions resulting in an approximately uniform damage profile to approximately 16 dpa. Pristine and ionirradiated regions of the nanocrystalline Ni films were characterized by conventional transmission electron microscopy and precession electron diffraction microscopy. Precession electron diffraction microscopy provided additional insight into the texture, phase, and grain boundary distribution resulting from the displacement damage that could not be obtained from traditional electron microscopy techniques. For the nanocrystalline nickel film studied, this included the growth in number and percentage of a metastable hexagonal closed packed phase grains and the formation of large <001> textured face centered cubic grains. The application of precession electron diffraction microscopy to characterize other nanocrystalline metals, which are being considered for radiation tolerant applications, will permit a comparison of materials that goes beyond the dominant length scale to consider the effects of local phase, texture, and grain boundary or interface information.

  19. Production and distribution of aberrations in resting or cycling human lymphocytes following Fe-ion or Cr-ion irradiation: Emphasis on single track effects

    NASA Astrophysics Data System (ADS)

    Deperas-Standylo, Joanna; Lee, Ryonfa; Nasonova, Elena; Ritter, Sylvia; Gudowska-Nowak, Ewa

    2012-09-01

    In the present study we examined the cytogenetic effects of 177 MeV/u Fe-ions (LET = 335 keV/?m) and 4.1 MeV/u Cr-ions (LET = 3160 keV/?m) in human lymphocytes under exposure conditions that result on average in one particle hit per cell nucleus. In non-cycling (G0-phase) lymphocytes the induction and the repair of excess fragments was measured by means of the premature chromosome condensation (PCC) technique and the distribution of breaks among cells was analysed. The PCC-data were further compared with those reported recently for stimulated lymphocytes at the first post-irradiation mitosis. Our experiments show that a single nuclear traversal by a Fe-ion produced more initial chromatin breakage than one Cr-ion, but after 24 h of repair the number of excess fragments/cell was similar for both ion species. All distributions of aberrations were overdispersed. For low energy Cr-ions, where the track radius is smaller than the radius of the cell nucleus, the data could be well described by a Neyman type A distribution. In contrast, the data obtained for high energy Fe-ions were fitted with a convoluted Poisson-Neyman distribution to account for the fact that the dose is deposited not only in the cell actually traversed but also in neighbouring cells. By applying metaphase analysis a different picture emerged with respect to the aberration yield, i.e. more aberrations were detected in cells exposed to Fe-ions than in those irradiated with Cr-ions. Yet, as observed for non-cycling lymphocytes all aberration distributions generated for metaphase cells were overdispersed. The obtained results are discussed with respect to differences in particle track structure. Additionally, the impact of confounding factors such as apoptosis that affect the number of aberrations expressed in a cell population is addressed.

  20. Formation of methyl formate after cosmic ion irradiation of icy grain mantles

    NASA Astrophysics Data System (ADS)

    Modica, P.; Palumbo, M. E.

    2010-09-01

    Context. Methyl formate (HCOOCH3) is a complex organic molecule detected in hot cores and hot corinos. Gas-phase chemistry fails to reproduce its observed abundance, which usually varies between 10-7 and 10-9 with respect to H2. Aims: Laboratory experiments were performed in order to investigate a solid-state route of methyl formate formation, to obtain an estimate of the amount that can be formed, and to verify whether it can account for the observed abundances. Methods: Several solid samples (16 K) of astrophysical interest were analyzed by infrared spectroscopy in the 4400-400 cm-1 range. The infrared spectral characteristics of frozen methyl formate were studied by deriving their band strength values. The effects produced upon warm-up of the samples were analyzed comparing the spectra taken at different temperatures. In order to study the formation and destruction mechanism of methyl formate in the interstellar ices, a binary mixture of methanol (CH3OH) and carbon monoxide (CO) ice and a sample of pure methanol were irradiated at 16 K with 200 keV protons. Methyl formate was identified through its fundamental mode (CH3 rocking) at about 1160 cm-1. Results: We present the mid-infrared methyl formate ice spectrum showing both the amorphous (16 K) and the crystalline (110 K) structure. We report novel measurements of the band strength values of the six main methyl formate bands. We prove the formation and the destruction of methyl formate after irradiation of CH3OH and a CO:CH3OH mixture. Extrapolating our results to the interstellar medium conditions we found that the production timescale of methyl formate agrees well with the evolutionary time of molecular clouds. The comparison with the observational data indicates that the amount of methyl formate formed after irradiation can account for the observed abundances. Conclusions: The present results allow us to suggest that gas phase methyl formate observed in dense molecular clouds is formed in the solid state after cosmic ion irradiation of icy grain mantles containing CO and CH3OH and released to the gas phase after desorption of icy mantles.