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Sample records for annual absorbed gamma

  1. Absorbed dose rates in tissue from prompt gamma emissions from near-thermal neutron absorption

    DOE PAGES

    Schwahn, Scott O.

    2015-10-01

    Prompt gamma emission data from the International Atomic Energy Agency s Prompt Gamma-ray Neutron Activation Analysis database are analyzed to determine the absorbed dose rates in tissue to be expected when natural elements are exposed in a near-thermal neutron environment.

  2. A geochemical assessment of terrestrial gamma-ray absorbed dose rates.

    PubMed

    Wollenberg, H A; Smith, A R

    1990-02-01

    A survey of the geochemical literature and unpublished data has resulted in the classification of the concentrations of the naturally occurring radioelements U, Th, and K by their associated rock types. A data base of over 2500 entries has been compiled, permitting calculation of terrestrial gamma-ray absorbed dose rates. The general lithology of terrains may be distinguished by their radioelement ratios, relative abundances, and total gamma radioactivities. The gamma-ray absorbed dose rates in air above igneous rocks generally vary with their silica contents, and with the exception of shale, sedimentary rocks have lower K:U and K:Th ratios than most igneous rocks. The appreciable difference between the overall mean terrestrial gamma-ray dose rate for rock of the continental surface (approximately 7 X 10(-8) Gy h-1) and the mean dose rate from field measurements over soil (approximately 5 X 10(-8) Gy h-1) is explained by the substantial differences between radioelement concentrations of soil and rock, differences that may vary markedly with rock type.

  3. Effect of low-Z absorber's thickness on gamma-ray shielding parameters

    NASA Astrophysics Data System (ADS)

    Mann, Kulwinder Singh; Heer, Manmohan Singh; Rani, Asha

    2015-10-01

    Gamma ray shielding behaviour of any material can be studied by various interaction parameters such as total mass attenuation coefficient (μm); half value layer (HVL); tenth value layer (TVL); effective atomic number (Zeff), electron density (Nel), effective atomic weight (Aeff) and buildup factor. For gamma rays, the accurate measurements of μm (cm2 g-1) theoretically require perfect narrow beam irradiation geometry. However, the practical geometries used for the experimental investigations deviate from perfect-narrowness thereby the multiple scattered photons cause systematic errors in the measured values of μm. Present investigation is an attempt to find the optimum value of absorber thickness (low-Z) for which these errors are insignificant and acceptable. Both experimental and theoretical calculations have been performed to investigate the effect of absorber's thickness on μm of six low-Z (10gamma-ray energies 661.66 keV, 1173.24 keV and 1332.50 keV. A computer program (GRIC2-toolkit) was designed for theoretical evaluation of shielding parameters of any material. Good agreement of theoretical and measured values of μm was observed for all absorbers with thickness ≤0.5 mean free paths, thus considered it as optimum thickness for low-Z materials in the selected energy range. White cement was found to possess maximum shielding effectiveness for the selected gamma rays.

  4. Effect of gamma ray absorbed dose on the FET transistor parameters

    NASA Astrophysics Data System (ADS)

    Eslami, Baharak; Ashrafi, Saleh

    This article tries to explain a modified method on dosimetry, based on electronic solid state including MOSFET (metal oxide semiconductor field effect) transistors. For this purpose, behavior of two models of MOSFETs has been studied as a function of the absorbed dose. The MOSFETs were irradiated at room temperature by 137Cs gamma ray source in the dose range of 1-5 Gy. Threshold voltage variation of investigated samples has been studied based on their transfer characteristic curves (TF) and also using the readout circuit (RC). For evaluation of laboratory samples sensitivity at different operating conditions, different biases were applied on the gate. In practical applications of radiation dosimetry, a significant change occurs in the threshold voltage of irradiated MOSFETs. And sensitivity of these MOSFETs is increased with increasing the bias values. Therefore, these transistors can be excellent candidates as low-cost sensors for systems that are capable of measuring gamma radiation dose.

  5. Study of natural radionuclide and absorbed gamma dose in Ukhimath area of Garhwal Himalaya, India.

    PubMed

    Rautela, B S; Yadav, M; Bourai, A A; Joshi, V; Gusain, G S; Ramola, R C

    2012-11-01

    Natural radiation is the largest contributor to the collective radiation dose of the world population. It is widely distributed in different geological formations such as soil, rocks, air and groundwater. In the present investigation, (226)Ra, (232)Th and (40)K were measured in soil samples of the Ukhimath region of Garhwal Himalaya, India using NaI(Tl) gamma-ray spectrometry. The activity concentrations of naturally occurring radionuclides (226)Ra, (232)Th and (40)K were found to vary from 38.4 ± 6.1 to 141.7 ± 11.9 Bq kg(-1) with an average of 80.5 Bq kg(-1), 57.0 ± 7.5 to 155.9 ± 12.4 Bq kg(-1) with an average of 118.9 Bq kg(-1) and 9.0 ± 3.0 to 672.8 ± 25.9 Bq kg(-1) with an average of 341 Bq kg(-1), respectively. The total absorbed gamma dose rate varies from 70.4 to 169.1 nGy h(-1) with an average of 123.4 nGy h(-1). This study is important to generate a baseline data of radiation exposure in the area. Health hazard effects due to natural radiation exposure are discussed in details.

  6. Assessment of indoor absorbed gamma dose rate from natural radionuclides in concrete by the method of build-up factors.

    PubMed

    Manić, Vesna; Nikezic, Dragoslav; Krstic, Dragana; Manić, Goran

    2014-12-01

    The specific absorbed gamma dose rates, originating from natural radionuclides in concrete, were calculated at different positions of a detection point inside the standard room, as well as inside an example room. The specific absorbed dose rates corresponding to a wall with arbitrary dimensions and thickness were also evaluated, and appropriate fitting functions were developed, enabling dose rate calculation for most realistic rooms. In order to make calculation simpler, the expressions fitting the exposure build-up factors for whole (238)U and (232)Th radionuclide series and (40)K were derived in this work, as well as the specific absorbed dose rates from a point source in concrete. Calculated values of the specific absorbed dose rates at the centre point of the standard room for (238)U, (232)Th and (40)K are in the ranges of previously obtained data.

  7. Annual Patterns and Sources of Light-Absorbing Aerosols over Central Greenland

    NASA Astrophysics Data System (ADS)

    Hu, J.; Bergin, M. H.; Dibb, J. E.; Sheridan, P. J.; Ogren, J. A.

    2014-12-01

    The Arctic region has proven to be more responsive to recent changes in climate than other parts of the Earth. A key component of the Arctic climate is the Greenland ice sheet (GIS), which has the potential to dramatically influence sea level, depending on the amount of melting that occurs, as well as climate, through shifts in the regional radiation balance. Light-absorbing aerosols from biomass burning, fossil fuel combustion, and dust sources can potentially have a significant impact on the radiation balance of the GIS; however, in order to better understand their impact, it is important to first understand the annual trends of light-absorbing aerosols and their sources over the ice sheet. With this in mind, aerosol properties including the wavelength dependent aerosol light scattering and absorption coefficients have been continuously measured at Summit, Greenland since the spring of 2011. These measurements will be used to calculate the multi-wavelength single-scattering albedo (ω0) and absorption Ångström exponent, identify annual patterns of aerosols over the GIS and how they vary from year to year, detect events of high absorption, and determine the sources of the aerosols. Preliminary findings indicate that the aerosols have an absorption Ångström exponent of approximately 1, which is characteristic of black carbon (BC). Absorption and scattering coefficients are higher in the spring and summer (March-September) and consequently lower in the fall and winter (September-March). Absorption and single-scattering albedo are averaged over the sunlit months of April-August and are found to be highest and lowest, respectively, in the year of 2012, corresponding to the year of record melt extent over the GIS.

  8. Determination of the Absorbed Dose Rate to Water for the 18-mm Helmet of a Gamma Knife

    SciTech Connect

    Chung, Hyun-Tai; Park, Youngho; Hyun, Sangil; Choi, Yongsoo; Kim, Gi Hong; Kim, Dong Gyu; Chun, Kook Jin

    2011-04-01

    Purpose: To measure the absorbed dose rate to water of {sup 60}Co gamma rays of a Gamma Knife Model C using water-filled phantoms (WFP). Methods and Materials: Spherical WFP with an equivalent water depth of 5, 7, 8, and 9 cm were constructed. The dose rates at the center of an 18-mm helmet were measured in an 8-cm WFP (WFP-3) and two plastic phantoms. Two independent measurement systems were used: one was calibrated to an air kerma (Set I) and the other was calibrated to the absorbed dose to water (Set II). The dose rates of WFP-3 and the plastic phantoms were converted to dose rates for an 8-cm water depth using the attenuation coefficient and the equivalent water depths. Results: The dose rate measured at the center of WFP-3 using Set II was 2.2% and 1.0% higher than dose rates measured at the center of the two plastic phantoms. The measured effective attenuation coefficient of Gamma Knife photon beam in WFPs was 0.0621 cm{sup -1}. After attenuation correction, the difference between the dose rate at an 8-cm water depth measured in WFP-3 and dose rates in the plastic phantoms was smaller than the uncertainty of the measurements. Conclusions: Systematic errors related to the characteristics of the phantom materials in the dose rate measurement of a Gamma Knife need to be corrected for. Correction of the dose rate using an equivalent water depth and attenuation provided results that were more consistent.

  9. Absorbed Gamma-Ray Doses due to Natural Radionuclides in Building Materials

    SciTech Connect

    Aguiar, Vitor A. P.; Medina, Nilberto H.; Moreira, Ramon H.; Silveira, Marcilei A. G.

    2010-05-21

    This work is devoted to the application of high-resolution gamma-ray spectrometry in the study of the effective dose coming from naturally occurring radionuclides, namely {sup 40}K, {sup 232}Th and {sup 238}U, present in building materials such as sand, cement, and granitic gravel. Four models were applied to estimate the effective dose and the hazard indices. The maximum estimated effective dose coming from the three reference rooms considered is 0.90(45) mSv/yr, and maximum internal hazard index is 0.77(24), both for the compact clay brick reference room. The principal gamma radiation sources are cement, sand and bricks.

  10. Absorbed Gamma-Ray Doses due to Natural Radionuclides in Building Materials

    NASA Astrophysics Data System (ADS)

    Aguiar, Vitor A. P.; Medina, Nilberto H.; Moreira, Ramon H.; Silveira, Marcilei A. G.

    2010-05-01

    This work is devoted to the application of high-resolution gamma-ray spectrometry in the study of the effective dose coming from naturally occurring radionuclides, namely 40K, 232Th and 238U, present in building materials such as sand, cement, and granitic gravel. Four models were applied to estimate the effective dose and the hazard indices. The maximum estimated effective dose coming from the three reference rooms considered is 0.90(45) mSv/yr, and maximum internal hazard index is 0.77(24), both for the compact clay brick reference room. The principal gamma radiation sources are cement, sand and bricks.

  11. ESR spectroscopy for detecting gamma-irradiated dried vegetables and estimating absorbed doses

    NASA Astrophysics Data System (ADS)

    Kwon, Joong-Ho; Chung, Hyung-Wook; Byun, Myung-Woo

    2000-03-01

    In view of an increasing demand for food irradiation technology, the development of a reliable means of detection for the control of irradiated foods has become necessary. Various vegetable food materials (dried cabbage, carrot, chunggyungchae, garlic, onion, and green onion), which can be legally irradiated in Korea, were subjected to a detection study using ESR spectroscopy. Correlation coefficients ( R2) between absorbed doses (2.5-15 kGy) and their corresponding ESR signals were identified from ESR signals. Pre-established threshold values were successfully applied to the detection of 54 coded unknown samples of dried clean vegetables ( chunggyungchae, Brassica camestris var. chinensis), both non-irradiated and irradiated. The ESR signals of irradiated chunggyungchae decreased over a longer storage time, however, even after 6 months of ambient storage, these signals were still distinguishable from those of non-irradiated samples. The most successful estimates of absorbed dose (5 and 8 kGy) were obtained immediately after irradiation using a quadratic fit with average values of 4.85 and 8.65 kGy being calculated.

  12. Simulation and Measurement of Absorbed Dose from 137 Cs Gammas Using a Si Timepix Detector

    NASA Technical Reports Server (NTRS)

    Stoffle, Nicholas; Pinsky, Lawrence; Empl, Anton; Semones, Edward

    2011-01-01

    The TimePix readout chip is a hybrid pixel detector with over 65k independent pixel elements. Each pixel contains its own circuitry for charge collection, counting logic, and readout. When coupled with a Silicon detector layer, the Timepix chip is capable of measuring the charge, and thus energy, deposited in the Silicon. Measurements using a NIST traceable 137Cs gamma source have been made at Johnson Space Center using such a Si Timepix detector, and this data is compared to simulations of energy deposition in the Si layer carried out using FLUKA.

  13. Assessment of absorbed dose to thyroid, parotid and ovaries in patients undergoing Gamma Knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Hasanzadeh, H.; Sharafi, A.; Allah Verdi, M.; Nikoofar, A.

    2006-09-01

    Stereotactic radiosurgery was originally introduced by Lars Leksell in 1951. This treatment refers to the noninvasive destruction of an intracranial target localized stereotactically. The purpose of this study was to identify the dose delivered to the parotid, ovaries, testis and thyroid glands during the Gamma Knife radiosurgery procedure. A three-dimensional, anthropomorphic phantom was developed using natural human bone, paraffin and sodium chloride as the equivalent tissue. The phantom consisted of a thorax, head and neck and hip. In the natural places of the thyroid, parotid (bilateral sides) and ovaries (midline), some cavities were made to place TLDs. Three TLDs were inserted in a batch with 1 cm space between the TLDs and each batch was inserted into a single cavity. The final depth of TLDs was 3 cm from the surface for parotid and thyroid and was 15 cm for the ovaries. Similar batches were placed superficially on the phantom. The phantom was gamma irradiated using a Leksell model C Gamma Knife unit. Subsequently, the same batches were placed superficially over the thyroid, parotid, testis and ovaries in 30 patients (15 men and 15 women) who were undergoing radiosurgery treatment for brain tumours. The mean dosage for treating these patients was 14.48 ± 3.06 Gy (10.5-24 Gy) to a mean tumour volume of 12.30 ± 9.66 cc (0.27-42.4 cc) in the 50% isodose curve. There was no significant difference between the superficial and deep batches in the phantom studies (P-value < 0.05). The mean delivered doses to the parotid, thyroid, ovaries and testis in human subjects were 21.6 ± 15.1 cGy, 9.15 ± 3.89 cGy, 0.47 ± 0.3 cGy and 0.53 ± 0.31 cGy, respectively. The data can be used in making decisions for special clinical situations such as treating pregnant patients or young patients with benign lesions who need radiosurgery for eradication of brain tumours.

  14. 'Self-absorbed' GeV light curves of gamma-ray burst afterglows

    SciTech Connect

    Panaitescu, A.; Vestrand, W. T.; Woźniak, P.

    2014-06-10

    We investigate the effect that the absorption of high-energy (above 100 MeV) photons produced in gamma-ray burst afterglow shocks has on the light curves and spectra of Fermi Large Area Telescope (LAT) afterglows. Afterglows produced by the interaction of a relativistic outflow with a wind-like medium peak when the blast wave deceleration sets in, and the afterglow spectrum could be hardening before that peak, as the optical thickness to pair formation is decreasing. In contrast, in afterglows produced in the interaction with a homogeneous medium, the optical thickness to pair formation should increase and yield a light curve peak when it reaches unity, followed by a fast light curve decay, accompanied by spectral softening. If energy is injected in the blast wave, then the accelerated increase of the optical thickness yields a convex afterglow light curve. Other features, such as a double-peak light curve or a broad hump, can arise from the evolution of the optical thickness to photon-photon absorption. Fast decays and convex light curves are seen in a few LAT afterglows, but the expected spectral softening is rarely seen in (and difficult to measure with) LAT observations. Furthermore, for the effects of photon-photon attenuation to shape the high-energy afterglow light curve without attenuating it too much, the ejecta initial Lorentz factor must be in a relatively narrow range (50-200), which reduces the chance of observing those effects.

  15. High-Resolution Hard X-Ray and Gamma-Ray Spectrometers Based on Superconducting Absorbers Coupled to Superconducting Transition Edge Sensors

    SciTech Connect

    van den Berg, M.; Chow, D.; Loshak, A.; Cunningham, M.F.; Barbee, T.W.; Matthias, F.; Labov, S.E.

    2000-09-21

    We are developing detectors based on bulk superconducting absorbers coupled to superconducting transition edge sensors (TES) for high-resolution spectroscopy of hard X-rays and soft gamma-rays. We have achieved an energy resolution of 70 eV FWHM at 60 keV using a 1 x 1 x 0.25 mm{sup 3} Sn absorber coupled to a Mo/Cu multilayer TES with a transition temperature of 100 mK. The response of the detector is compared with a simple model using only material properties data and characteristics derived from IV-measurements. We have also manufactured detectors using superconducting absorbers with a higher stopping power, such as Pb and Ta. We present our first measurements of these detectors, including the thermalization characteristics of the bulk superconducting absorbers. The differences in performance between the detectors are discussed and an outline of the future direction of our detector development efforts is given.

  16. Assessment of Annual Effective Dose for Natural Radioactivity of Gamma Emitters in Biscuit Samples in Iraq.

    PubMed

    Abojassim, Ali Abid; Al-Alasadi, Lubna A; Shitake, Ahmed R; Al-Tememie, Faeq A; Husain, Afnan A

    2015-09-01

    Biscuits are an important type of food, widely consumed by babies in Iraq and other countries. This work uses gamma spectroscopy to measure the natural radioactivity due to long-lived gamma emitters in children's biscuits; it also estimates radiation hazard indices, that is, the radium equivalent activity, the representative of gamma level index, the internal hazard index, and the annual effective dose in children. Ten samples were collected from the Iraqi market from different countries of origin. The average specific activities for (226)Ra, (232)Th, and (40)K were 9.390, 3.1213, and 214.969 Bq/kg, respectively, but the average of the radium equivalent activity and the internal hazard index were 33.101 Bq/kg and 0.107, respectively. The total average annual effective dose from consumption by adults, children, and infants is estimated to be 0.655, 1.009, and 0.875 mSv, respectively. The values found for specific activity, radiation hazard indices, and annual effective dose in all samples in this study were lower than worldwide median values for all groups; therefore, these values are found to be safe.

  17. Evaluation of selective solar absorber surfaces. Semi-annual report, October 1, 1980-March 24, 1981

    SciTech Connect

    Osiecki, R.A.

    1981-04-01

    Testing of sample selective solar absorber coatings is reported. The first goal is to attempt to accelerate the optical property degradation of the coatings through exposure to a high humidity/high temperature environment. The second goal is the subsequent analysis of degraded and non-degraded coatings in an effort to determine the degradation mechanisms which operate on each coating. Surfaces tested included black chrome on aluminum, on copper, and on nickel plated copper, copper oxide/copper on mild steel, nickel-chromium oxide on nickel foil, chromate conversion coating, and a thickness sensitive silicone based paint. The optical properties of the samples in environmental exposure are tabulated. These properties include solar absorptance and near-normal emittance. (LEW)

  18. LOW-RESOLUTION SPECTROSCOPY OF GAMMA-RAY BURST OPTICAL AFTERGLOWS: BIASES IN THE SWIFT SAMPLE AND CHARACTERIZATION OF THE ABSORBERS

    SciTech Connect

    Fynbo, J. P. U.; Malesani, D.; Vreeswijk, P. M.; Hjorth, J.; Sollerman, J.; Thoene, C. C.; Jakobsson, P.; Bjoernsson, G.; De Cia, A.; Prochaska, J. X.; Nardini, M.; Chen, H.-W.; Bloom, J. S.; Castro-Tirado, A. J.; Gorosabel, J.; Christensen, L.; Fruchter, A. S.

    2009-12-01

    We present a sample of 77 optical afterglows (OAs) of Swift detected gamma-ray bursts (GRBs) for which spectroscopic follow-up observations have been secured. Our first objective is to measure the redshifts of the bursts. For the majority (90%) of the afterglows, the redshifts have been determined from the spectra. We provide line lists and equivalent widths (EWs) for all detected lines redward of Ly{alpha} covered by the spectra. In addition to the GRB absorption systems, these lists include line strengths for a total of 33 intervening absorption systems. We discuss to what extent the current sample of Swift bursts with OA spectroscopy is a biased subsample of all Swift detected GRBs. For that purpose we define an X-ray-selected statistical sample of Swift bursts with optimal conditions for ground-based follow-up from the period 2005 March to 2008 September; 146 bursts fulfill our sample criteria. We derive the redshift distribution for the statistical (X-ray selected) sample and conclude that less than 18% of Swift bursts can be at z > 7. We compare the high-energy properties (e.g., {gamma}-ray (15-350 keV) fluence and duration, X-ray flux, and excess absorption) for three subsamples of bursts in the statistical sample: (1) bursts with redshifts measured from OA spectroscopy; (2) bursts with detected optical and/or near-IR afterglow, but no afterglow-based redshift; and (3) bursts with no detection of the OA. The bursts in group (1) have slightly higher {gamma}-ray fluences and higher X-ray fluxes and significantly less excess X-ray absorption than bursts in the other two groups. In addition, the fractions of dark bursts, defined as bursts with an optical to X-ray slope {beta}{sub OX} < 0.5, is 14% in group (1), 38% in group (2), and >39% in group (3). For the full sample, the dark burst fraction is constrained to be in the range 25%-42%. From this we conclude that the sample of GRBs with OA spectroscopy is not representative for all Swift bursts, most likely due

  19. A radiochromic folm dosimeter for gamma radiation in the absorbed-dose range 0.1-10 kGy

    NASA Astrophysics Data System (ADS)

    Khan, Hasan M.; Farahani, Mahnaz; William L., McLaughlin

    A commercially available leuco-dye film (FWT-63-02), having a thickness of 0.55 mm, has been investigated spectrophotometrically for its characteristics as a radiochromic dosimeter and for its potential use in food-irradiation applications. The γ-ray irradiation of the nearly colorless, transparent film induces blue color with an absorption maximum at 600 nm. The increase in absorbance at 600 nm per unit thickness of film (Δ A mm -1) is linear with dose in the dose range up to 8 kGy, with a slope of 0.91 mm -1·kGy -1. After a modest additional increase during the first day following irradiation, the radiation-induced color is stable when stored at room temperature at least for 5 weeks. The response slope is 16% higher when stored at 60°C, however, after the initial 1-day increase it is stable for several weeks when stored at that temperature. The response of the dosimeter is independent of dose rate in the range 0.5-170 Gy min -1.

  20. AN INDEPENDENT MEASUREMENT OF THE INCIDENCE OF Mg II ABSORBERS ALONG GAMMA-RAY BURST SIGHT LINES: THE END OF THE MYSTERY?

    SciTech Connect

    Cucchiara, A.; Prochaska, J. X.; Fynbo, J. P. U.; Fox, D. B.; Chen, H.-W.; Cooksey, K. L.; Cenko, S. B.; Bloom, J. S.; Perley, D.; Berger, E.; Chornock, R.; Tanvir, N. R.; D'Elia, V.; Lopez, S.; De Jaeger, T.

    2013-08-20

    In 2006, Prochter et al. reported a statistically significant enhancement of very strong Mg II absorption systems intervening the sight lines to gamma-ray bursts (GRBs) relative to the incidence of such absorption along quasar sight lines. This counterintuitive result has inspired a diverse set of astrophysical explanations (e.g., dust, gravitational lensing) but none of these has obviously resolved the puzzle. Using the largest set of GRB afterglow spectra available, we reexamine the purported enhancement. In an independent sample of GRB spectra with a survey path three times larger than Prochter et al., we measure the incidence per unit redshift of {>=}1 A rest-frame equivalent width Mg II absorbers at z Almost-Equal-To 1 to be l(z) = 0.18 {+-} 0.06. This is fully consistent with current estimates for the incidence of such absorbers along quasar sight lines. Therefore, we do not confirm the original enhancement and suggest those results suffered from a statistical fluke. Signatures of the original result do remain in our full sample (l(z) shows an Almost-Equal-To 1.5 enhancement over l(z){sub QSO}), but the statistical significance now lies at Almost-Equal-To 90% c.l. Restricting our analysis to the subset of high-resolution spectra of GRB afterglows (which overlaps substantially with Prochter et al.), we still reproduce a statistically significant enhancement of Mg II absorption. The reason for this excess, if real, is still unclear since there is no connection between the rapid afterglow follow-up process with echelle (or echellette) spectrographs and the detectability of strong Mg II doublets. Only a larger sample of such high-resolution data will shed some light on this matter.

  1. Low-resolution Spectroscopy of Gamma-ray Burst Optical Afterglows: Biases in the Swift Sample and Characterization of the Absorbers

    NASA Astrophysics Data System (ADS)

    Fynbo, J. P. U.; Jakobsson, P.; Prochaska, J. X.; Malesani, D.; Ledoux, C.; de Ugarte Postigo, A.; Nardini, M.; Vreeswijk, P. M.; Wiersema, K.; Hjorth, J.; Sollerman, J.; Chen, H.-W.; Thöne, C. C.; Björnsson, G.; Bloom, J. S.; Castro-Tirado, A. J.; Christensen, L.; De Cia, A.; Fruchter, A. S.; Gorosabel, J.; Graham, J. F.; Jaunsen, A. O.; Jensen, B. L.; Kann, D. A.; Kouveliotou, C.; Levan, A. J.; Maund, J.; Masetti, N.; Milvang-Jensen, B.; Palazzi, E.; Perley, D. A.; Pian, E.; Rol, E.; Schady, P.; Starling, R. L. C.; Tanvir, N. R.; Watson, D. J.; Xu, D.; Augusteijn, T.; Grundahl, F.; Telting, J.; Quirion, P.-O.

    2009-12-01

    We present a sample of 77 optical afterglows (OAs) of Swift detected gamma-ray bursts (GRBs) for which spectroscopic follow-up observations have been secured. Our first objective is to measure the redshifts of the bursts. For the majority (90%) of the afterglows, the redshifts have been determined from the spectra. We provide line lists and equivalent widths (EWs) for all detected lines redward of Lyα covered by the spectra. In addition to the GRB absorption systems, these lists include line strengths for a total of 33 intervening absorption systems. We discuss to what extent the current sample of Swift bursts with OA spectroscopy is a biased subsample of all Swift detected GRBs. For that purpose we define an X-ray-selected statistical sample of Swift bursts with optimal conditions for ground-based follow-up from the period 2005 March to 2008 September; 146 bursts fulfill our sample criteria. We derive the redshift distribution for the statistical (X-ray selected) sample and conclude that less than 18% of Swift bursts can be at z > 7. We compare the high-energy properties (e.g., γ-ray (15-350 keV) fluence and duration, X-ray flux, and excess absorption) for three subsamples of bursts in the statistical sample: (1) bursts with redshifts measured from OA spectroscopy; (2) bursts with detected optical and/or near-IR afterglow, but no afterglow-based redshift; and (3) bursts with no detection of the OA. The bursts in group (1) have slightly higher γ-ray fluences and higher X-ray fluxes and significantly less excess X-ray absorption than bursts in the other two groups. In addition, the fractions of dark bursts, defined as bursts with an optical to X-ray slope βOX < 0.5, is 14% in group (1), 38% in group (2), and >39% in group (3). For the full sample, the dark burst fraction is constrained to be in the range 25%-42%. From this we conclude that the sample of GRBs with OA spectroscopy is not representative for all Swift bursts, most likely due to a bias against the

  2. FY06 Annual Report: Amorphous Semiconductors for Gamma Radiation Detection (ASGRAD)

    SciTech Connect

    Johnson, Bradley R.; Riley, Brian J.; Crum, Jarrod V.; Sundaram, S. K.; Henager, Charles H.; Zhang, Yanwen; Shutthanandan, V.

    2007-01-01

    We describe progress in the development of new materials for portable, room-temperature, gamma-radiation detection at Pacific Northwest National Laboratory at the Hanford Site in Washington State. High Z, high resistivity, amorphous semiconductors are being designed for use as solid-state detectors at near ambient temperatures; principles of operation are analogous to single-crystal semiconducting detectors. Amorphous semiconductors have both advantages and disadvantages compared to single crystals, and this project is developing methods to mitigate technical problems and design optimized material for gamma detection. Several issues involved in the fabrication of amorphous semiconductors are described, including reaction thermodynamics and kinetics, the development of pyrolytic coating, and the synthesis of ingots. The characterization of amorphous semiconductors is described, including sectioning and polishing protocols, optical microscopy, X-ray diffraction, scanning electron microscopy, optical spectroscopy, particle-induced X-ram emission, Rutherford backscattering, and electrical testing. Then collaboration with the University of Illinois at Urbana-Champaign is discussed in the areas of Hall-effect measurements and current voltage data. Finally, we discuss the strategy for continuing the program.

  3. Radon loss from encapsulated sediments in Ge gamma-ray spectrometry for the annual radiation dose determination in luminescence dating

    NASA Astrophysics Data System (ADS)

    de Corte, F.; Vandenberghe, D.; de Wispelaere, A.; Buylaert, J.-P.; van den Haute, P.

    2006-01-01

    In Ge gamma-ray spectrometry for the annual radiation dose determination in the luminescence dating of sediments, the picture of 226Ra enrichment or depletion (in the 238U decay series) obtained via measurement of its 214Pb and 214Bi daughters may be disturbed by the 222Rn-content of the sample being decreased due to manipulations such as drying and pulverizing. Therefore, it is common practice to start the measurement only about 1 month after encapsulating the material, after which the 226Ra(1600 a)- 222Rn(3.82 d) mother-daughter equilibrium is re-established. Evidently, this only holds on condition that no significant escape of Rn occurs out of the sediment after making it up for counting. In order to experimentally investigate this effect, in the present work measurements were carried out with various types of dried and pulverized sediments that were either encapsulated in screw-cap polystyrene vials or in sealed glass containers, or that were mixed with molten wax followed by solidification in a cylindrical geometry. From the results obtained, it could be concluded that preparation and counting of the sediment-wax mixture is the method of choice.

  4. Sound Absorbers

    NASA Astrophysics Data System (ADS)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  5. Key comparison BIPM.RI(I)-K4 of the absorbed dose to water standards of the PTB, Germany and the BIPM in 60Co gamma radiation

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Burns, D. T.; Kapsch, R.-P.; Krauss, A.

    2016-01-01

    An indirect comparison has been made of the standards for absorbed dose to water in 60Co radiation of the Physikalisch-Technische Bundesanstalt, (PTB), Germany and of the Bureau International des Poids et Mesures (BIPM). The measurements at the BIPM were carried out in October 2015. The comparison result, based on the calibration coefficients for two transfer standards and evaluated as a ratio of the PTB and the BIPM standards for absorbed dose to water, is 0.9977 with a combined standard uncertainty of 3.8 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  6. High Levels of Dietary Supplement Vitamins A, C and E are Absorbed in the Small Intestine and Protect Nutrient Transport Against Chronic Gamma Irradiation.

    PubMed

    Roche, Marjolaine; Neti, Prasad V S V; Kemp, Francis W; Azzam, Edouard I; Ferraris, Ronaldo P; Howell, Roger W

    2015-11-01

    We examined nutrient transport in the intestines of mice exposed to chronic low-LET 137Cs gamma rays. The mice were whole-body irradiated for 3 days at dose rates of 0, 0.13 and 0.20 Gy/h, for total dose delivery of 0, 9.6 or 14.4 Gy, respectively. The mice were fed either a control diet or a diet supplemented with high levels of vitamins A, C and E. Our results showed that nutrient transport was perturbed by the chronic irradiation conditions. However, no apparent alteration of the macroscopic intestinal structures of the small intestine were observed up to day 10 after initiating irradiation. Jejunal fructose uptake measured in vitro was strongly affected by the chronic irradiation, whereas uptake of proline, carnosine and the bile acid taurocholate in the ileum was less affected. D-glucose transport did not appear to be inhibited significantly by either 9.6 or 14.4 Gy exposure. In the 14.4 Gy irradiated groups, the diet supplemented with high levels of vitamins A, C and E increased intestinal transport of fructose compared to the control diet (day 10; t test, P = 0.032), which correlated with elevated levels of vitamins A, C and E in the plasma and jejunal enterocytes. Our earlier studies with mice exposed acutely to 137Cs gamma rays demonstrated significant protection for transport of fructose, glucose, proline and carnosine. Taken together, these results suggest that high levels of vitamins A, C and E dietary supplements help preserve intestinal nutrient transport when intestines are irradiated chronically or acutely with low-LET gamma rays. PMID:26484399

  7. High Levels of Dietary Supplement Vitamins A, C and E are Absorbed in the Small Intestine and Protect Nutrient Transport Against Chronic Gamma Irradiation.

    PubMed

    Roche, Marjolaine; Neti, Prasad V S V; Kemp, Francis W; Azzam, Edouard I; Ferraris, Ronaldo P; Howell, Roger W

    2015-11-01

    We examined nutrient transport in the intestines of mice exposed to chronic low-LET 137Cs gamma rays. The mice were whole-body irradiated for 3 days at dose rates of 0, 0.13 and 0.20 Gy/h, for total dose delivery of 0, 9.6 or 14.4 Gy, respectively. The mice were fed either a control diet or a diet supplemented with high levels of vitamins A, C and E. Our results showed that nutrient transport was perturbed by the chronic irradiation conditions. However, no apparent alteration of the macroscopic intestinal structures of the small intestine were observed up to day 10 after initiating irradiation. Jejunal fructose uptake measured in vitro was strongly affected by the chronic irradiation, whereas uptake of proline, carnosine and the bile acid taurocholate in the ileum was less affected. D-glucose transport did not appear to be inhibited significantly by either 9.6 or 14.4 Gy exposure. In the 14.4 Gy irradiated groups, the diet supplemented with high levels of vitamins A, C and E increased intestinal transport of fructose compared to the control diet (day 10; t test, P = 0.032), which correlated with elevated levels of vitamins A, C and E in the plasma and jejunal enterocytes. Our earlier studies with mice exposed acutely to 137Cs gamma rays demonstrated significant protection for transport of fructose, glucose, proline and carnosine. Taken together, these results suggest that high levels of vitamins A, C and E dietary supplements help preserve intestinal nutrient transport when intestines are irradiated chronically or acutely with low-LET gamma rays.

  8. A logNHI = 22.6 Damped Lyα Absorber in a Dark Gamma-Ray Burst: The Environment of GRB 050401

    NASA Astrophysics Data System (ADS)

    Watson, D.; Fynbo, J. P. U.; Ledoux, C.; Vreeswijk, P.; Hjorth, J.; Smette, A.; Andersen, A. C.; Aoki, K.; Augusteijn, T.; Beardmore, A. P.; Bersier, D.; Castro Cerón, J. M.; D'Avanzo, P.; Diaz-Fraile, D.; Gorosabel, J.; Hirst, P.; Jakobsson, P.; Jensen, B. L.; Kawai, N.; Kosugi, G.; Laursen, P.; Levan, A.; Masegosa, J.; Näränen, J.; Page, K. L.; Pedersen, K.; Pozanenko, A.; Reeves, J. N.; Rumyantsev, V.; Shahbaz, T.; Sharapov, D.; Sollerman, J.; Starling, R. L. C.; Tanvir, N.; Torstensson, K.; Wiersema, K.

    2006-12-01

    The optical afterglow spectrum of GRB 050401 (at z=2.8992+/-0.0004) shows the presence of a damped Lyα absorber (DLA), with logNHI=22.6+/-0.3. This is the highest column density ever observed in a DLA and is about 5 times larger than the strongest DLA detected so far in any QSO spectrum. From the optical spectrum, we also find a very large Zn column density, implying an abundance of [Zn/H]=-1.0+/-0.4. These large columns are supported by the early X-ray spectrum from Swift XRT, which shows a column density (in excess of Galactic) of logNH=22.21+0.06-0.08 assuming solar abundances (at z=2.9). The comparison of this X-ray column density, which is dominated by absorption due to α-chain elements, and the H I column density derived from the Lyα absorption line allows us to derive a metallicity for the absorbing matter of [α/H]=-0.4+/-0.3. The optical spectrum is reddened and can be well reproduced with a power law with SMC extinction, where AV=0.62+/-0.06. But the total optical extinction can also be constrained independent of the shape of the extinction curve: from the optical to X-ray spectral energy distribution, we find 0.5<~AV<~4.5. However, even this upper limit, independent of the shape of the extinction curve, is still well below the dust column that is inferred from the X-ray column density, i.e., AV=9.1+1.4-1.5. This discrepancy might be explained by a small dust content with high metallicity (low dust-to-metals ratio). ``Gray'' extinction cannot explain the discrepancy, since we are comparing the metallicity to a measurement of the total extinction (without reference to the reddening). Little dust with high metallicity may be produced by sublimation of dust grains or may naturally exist in systems younger than a few hundred megayears. Based in part on observations made at the European Southern Observatory, Paranal, Chile under program 075.D-0270, with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland

  9. EURAMET.RI(I)-S7 comparison of alanine dosimetry systems for absorbed dose to water measurements in gamma- and x-radiation at radiotherapy levels

    NASA Astrophysics Data System (ADS)

    Garcia, Tristan; Anton, Mathias; Sharpe, Peter

    2012-01-01

    The National Physical Laboratory (NPL), the Physikalisch-Technische Bundesanstalt (PTB) and the Laboratoire National Henri Becquerel (LNE-LNHB) are involved in the European project 'External Beam Cancer Therapy', a project of the European Metrology Research Programme. Within this project, the electron paramagnetic resonance (EPR)/alanine dosimetric method has been chosen for performing measurements in small fields such as those used in IMRT (intensity modulated radiation therapy). In this context, these three National Metrology Institutes (NMI) wished to compare the result of their alanine dosimetric systems (detector, modus operandi etc) at radiotherapy dose levels to check their consistency. This EURAMET.RI(I)-S7 comparison has been performed with the support of the Bureau International des Poids et Mesures (BIPM) which collected and distributed the results as a neutral organization, to ensure the comparison was 'blind'. Irradiations have been made under reference conditions by each laboratory in a 60Co beam and in an accelerator beam (10 MV or 12 MV) in a water phantom of 30 cm × 30 cm × 30 cm in a square field of 10 cm × 10 cm at the reference depth. Irradiations have been performed at known values of absorbed dose to water (Dw) within 10% of nominal doses of 5 Gy and 10 Gy, i.e. between 4.5 Gy and 5.5 Gy and between 9 Gy and 11 Gy, respectively. Each participant read out their dosimeters and assessed the doses using their own protocol (calibration curve, positioning device etc) as this comparison aims at comparing the complete dosimetric process. The results demonstrate the effectiveness of the EPR/alanine dosimetry systems operated by National Metrology Institutes as a method of assuring therapy level doses with the accuracy required. The maximum deviation in the ratio of measured to applied dose is less than 1%. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key

  10. Magnetic Microcalorimeter Gamma Detectors for High-Precision Non-Destructive Analysis, FY14 Extended Annual Report

    SciTech Connect

    Friedrich, S.

    2015-02-06

    Cryogenic gamma (γ) detectors with operating temperatures of ~0.1 K or below offer 10× better energy resolution than conventional high-purity germanium detectors that are currently used for non-destructive analysis (NDA) of nuclear materials. This can greatly increase the accuracy of NDA, especially at low-energies where gamma rays often have similar energies and cannot be resolved by Ge detectors. We are developing cryogenic γ–detectors based on metallic magnetic calorimeters (MMCs), which have the potential of higher resolution, faster count rates and better linearity than other cryogenic detector technologies. High linearity is essential to add spectra from different pixels in detector arrays that are needed for high sensitivity. Here we discuss the fabrication of a new generation of MMC γ–detectors in FY2014, and the resulting improvements in energy resolution and linearity of the new design. As an example of the type of NDA that cryogenic detectors enable, we demonstrate the direct detection of Pu-242 emissions with our MMC γ–detectors in the presence of Pu-240, and show that a quantitative NDA analysis agrees with the mass spectrometry

  11. SYNTH - Gamma Ray Spectrum Synthesizer

    2009-05-18

    SYNTH was designed to synthesize the results of typical gamma-ray spectroscopy experiments. The code allows a user to specify the physical characteristics of a gamma-ray source, the quantity of radionuclides emitting gamma radiation, the source-to-detector distance and the presence and type of any intervening absorbers, the size and type of the gamma-ray detector, and the electronic set-up used to gather the data.

  12. Gamma-gamma colliders

    SciTech Connect

    Kim, K.J.; Sessler, A.

    1996-06-01

    Gamma-gamma colliders make intense beams of gamma rays and have them collide so as to make elementary particles. The authors show, in this article, that constructing a gamma-gamma collider as an add-on to an electron-positron linear collider is possible with present technology and that it does not require much additional cost. Furthermore, they show that the resulting capability is very interesting from a particle physics point of view. An overview of a linear collider, with a second interaction region devoted to {gamma}{gamma} collisions is shown.

  13. Attenuation of external Bremsstrahlung in metallic absorbers

    SciTech Connect

    Dhaliwal, A.S.; Powar, M.S.; Singh, M. )

    1990-12-01

    In this paper attenuation of bremsstrahlung from {sup 147}Pm and {sup 170}Tm beta emitters has been studied in aluminum, copper, tin, and lead metallic absorbers. Bremsstrahlung spectra and mass attenuation coefficients for monoenergetic gamma rays are used to calculate theoretical attenuation curves. Magnetic deflection and beta stopping techniques are used to measure the integral bremsstrahlung intensities above 30 keV in different target thicknesses. Comparison of measured and calculated attenuation curves shows a good agreement for various absorbers, thus providing a test of this technique, which may be useful in understanding bremsstrahlung intensity buildup and in the design of optimum shielding for bremsstrahlung sources. It is found that the absorption of bremsstrahlung in metallic absorbers does not obey an exponential law and that absorbers act as energy filters.

  14. Composition for absorbing hydrogen

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Enz, Glenn L.

    1995-01-01

    A hydrogen absorbing composition. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  15. Composition for absorbing hydrogen

    DOEpatents

    Heung, L.K.; Wicks, G.G.; Enz, G.L.

    1995-05-02

    A hydrogen absorbing composition is described. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  16. Modelling Absorbent Phenomena of Absorbent Structure

    NASA Astrophysics Data System (ADS)

    Sayeb, S.; Ladhari, N.; Ben Hassen, M.; Sakli, F.

    Absorption, retention and strike through time, as evaluating criteria of absorbent structures quality were studied. Determination of influent parameters on these criteria were realized by using the design method of experimental sets. In this study, the studied parameters are: Super absorbent polymer (SAP)/fluff ratio, compression and the porosity of the non woven used as a cover stock. Absorption capacity and retention are mostly influenced by SAP/fluff ratio. However, strike through time is affected by compression. Thus, a modelling of these characteristics in function of the important parameter was established.

  17. Methods for absorbing neutrons

    DOEpatents

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  18. Externally tuned vibration absorber

    DOEpatents

    Vincent, Ronald J.

    1987-09-22

    A vibration absorber unit or units are mounted on the exterior housing of a hydraulic drive system of the type that is powered from a pressure wave generated, e.g., by a Stirling engine. The hydraulic drive system employs a piston which is hydraulically driven to oscillate in a direction perpendicular to the axis of the hydraulic drive system. The vibration absorbers each include a spring or other resilient member having one side affixed to the housing and another side to which an absorber mass is affixed. In a preferred embodiment, a pair of vibration absorbers is employed, each absorber being formed of a pair of leaf spring assemblies, between which the absorber mass is suspended.

  19. Advanced neutron absorber materials

    DOEpatents

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  20. Absorbing Outflows in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, Smita

    2002-01-01

    The goal of this program was a comprehensive multiwavelength study of absorption phenomena in active galactic nuclei (AGN). These include a variety of associated absorption systems: X-ray warm absorbers, X-ray cold absorbers. UV absorbers with high ionization lines, MgII absorbers, red quasars and BALQSOs. The aim is to determine the physical conditions in the absorbing outflows, study their inter-relations and their role in AGN. We designed several observing programs to achieve this goal: X-ray spectroscopy, UV spectroscopy, FLAY spectroscopy and X-ray imaging. We were very successful towards achieving the goal over the five year period as shown through following observing programs and papers. Copies of a few papers are attached with this report.

  1. Internal absorber solar collector

    DOEpatents

    Sletten, Carlyle J.; Herskovitz, Sheldon B.; Holt, F. S.; Sletten, E. J.

    1981-01-01

    Thin solar collecting panels are described made from arrays of small rod collectors consisting of a refracting dielectric rod lens with an absorber imbedded within it and a reflecting mirror coated on the back side of the dielectric rod. Non-tracking collector panels on vertical walls or roof tops receive approximately 90% of solar radiation within an acceptance zone 60.degree. in elevation angle by 120.degree. or more in the azimuth sectors with a collector concentration ratio of approximately 3.0. Miniaturized construction of the circular dielectric rods with internal absorbers reduces the weight per area of glass, plastic and metal used in the collector panels. No external parts or insulation are needed as heat losses are low due to partial vacuum or low conductivity gas surrounding heated portions of the collector. The miniature internal absorbers are generally made of solid copper with black selective surface and the collected solar heat is extracted at the collector ends by thermal conductivity along the absorber rods. Heat is removed from end fittings by use of liquid circulants. Several alternate constructions are provided for simplifying collector panel fabrication and for preventing the thermal expansion and contraction of the heated absorber or circulant tubes from damaging vacuum seals. In a modified version of the internal absorber collector, oil with temperature dependent viscosity is pumped through a segmented absorber which is now composed of closely spaced insulated metal tubes. In this way the circulant is automatically diverted through heated portions of the absorber giving higher collector concentration ratios than theoretically possible for an unsegmented absorber.

  2. Lipid-absorbing Polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.; Wallace, C. J.

    1973-01-01

    The removal of bile acids and cholesterol by polymeric absorption is discussed in terms of micelle-polymer interaction. The results obtained with a polymer composed of 75 parts PEO and 25 parts PB plus curing ingredients show an absorption of 305 to 309%, based on original polymer weight. Particle size effects on absorption rate are analyzed. It is concluded that crosslinked polyethylene oxide polymers will absorb water, crosslinked polybutadiene polymers will absorb lipids; neither polymer will absorb appreciable amounts of lipids from micellar solutions of lipids in water.

  3. Electron paramagnetic resonance measurements of absorbed dose in teeth from citizens of Ozyorsk.

    PubMed

    Wieser, A; Vasilenko, E; Aladova, E; Fattibene, P; Semiochkina, N; Smetanin, M

    2014-05-01

    In 1945, within the frame of the Uranium Project for the production of nuclear weapons, the Mayak nuclear facilities were constructed at the Lake Irtyash in the Southern Urals, Russia. The nuclear workers of the Mayak Production Association (MPA), who lived in the city of Ozyorsk, are the focus of epidemiological studies for the assessment of health risks due to protracted exposure to ionising radiation. Electron paramagnetic resonance measurements of absorbed dose in tooth enamel have already been used in the past, in an effort to validate occupational external doses that were evaluated in the Mayak Worker Dosimetry System. In the present study, 229 teeth of Ozyorsk citizens not employed at MPA were investigated for the assessment of external background exposure in Ozyorsk. The annually absorbed dose in tooth enamel from natural background radiation was estimated to be (0.7 ± 0.3) mGy. For citizens living in Ozyorsk during the time of routine noble gas releases of the MPA, which peaked in 1953, the average excess absorbed dose in enamel above natural background was (36 ± 29) mGy, which is consistent with the gamma dose obtained by model calculations. In addition, there were indications of possible accidental gaseous MPA releases that affected the population of Ozyorsk, during the early and late MPA operation periods, before 1951 and after 1960. PMID:24604722

  4. Investigation of natural effective gamma dose rates case study: Ardebil Province in Iran

    PubMed Central

    2012-01-01

    Gamma rays pose enough energy to induce chemical changes that may be biologically important for the normal functioning of body cells. The external exposure of human beings to natural environmental gamma radiation normally exceeds that from all man-made sources combined. In this research natural background gamma dose rates and corresponding annual effective doses were determined for selected cities of Ardebil province. Outdoor gamma dose rates were measured using an Ion Chamber Survey Meter in 105 locations in selected districts. Average absorbed doses for Ardebil, Sar-Ein, Germy, Neer, Shourabil Recreational Lake, and Kosar were determined as 265, 219, 344, 233, 352, and 358 nSv/h, respectively. Although dose rates recorded for Germi and Kosar are comparable with some areas with high natural radiation background, however, the dose rates in other districts are well below the levels reported for such locations. Average annual effective dose due to indoor and outdoor gamma radiation for Ardebil province was estimated as 1.73 (1.35–2.39) mSv, which is on average 2 times higher than the world population weighted average. PMID:23369115

  5. Radon survey and soil gamma doses in primary schools of Batman, Turkey.

    PubMed

    Damla, Nevzat; Aldemir, Kamuran

    2014-06-01

    A survey was conducted to evaluate levels of indoor radon and gamma doses in 42 primary schools located in Batman, southeastern Anatolia, Turkey. Indoor radon measurements were carried out using CR-39 solid-state nuclear track detector-based radon dosimeters. The overall mean annual (222)Rn activity in the surveyed area was found to be 49 Bq m(-3) (equivalent to an annual effective dose of 0.25 mSv). However, in one of the districts (Besiri) the maximum radon value turned out to be 307 Bq m(-3). The estimated annual effective doses are less than the recommended action level (3-10 mSv). It is found that the radon concentration decreases with increasing floor number. The concentrations of natural and artificial radioisotopes were determined using gamma-ray spectroscopy for soil samples collected in close vicinity of the studied schools. The mean gamma activity concentrations in the soil samples were 31, 25, 329 and 12 Bq kg(-1) for (226)Ra, (232)Th, (40)K and (137)Cs, respectively. The radiological parameters such as the absorbed dose rate in air and the annual effective dose equivalent were calculated. These radiological parameters were evaluated and compared with the internationally recommended values.

  6. Determination of neutron absorbed doses in lithium aluminates.

    PubMed

    Delfín Loya, A; Carrera, L M; Ureña-Núñez, F; Palacios, O; Bosch, P

    2003-04-01

    Lithium-based ceramics have been proposed as tritium breeders for fusion reactors. The lithium aluminate (gamma phase) seems to be thermally and structurally stable, the damages produced by neutron irradiation depend on the absorbed dose. A method based on the measurement of neutron activation of foils through neutron capture has been developed to obtain the neutron absorbed dose in lithium aluminates irradiated in the thermal column facility and in the fixed irradiation system of a Triga Mark III Nuclear Reactor. PMID:12672632

  7. The application of two-dimensional imaging to very high energy gamma ray astronomy. Annual report, 1 May 1991--30 April 1992

    SciTech Connect

    Weekes, T.C.

    1992-12-01

    After an introductory overview of gamma-ray astronomy, very brief summaries of research results are given. Summary topics may be grouped as follows: observations (survey of candidate gamma-ray sources; Cygnus X-3; Markarian 421; AGN`s: general survey; Crab observations: pulsar outburst; Geminga; AE Aqr; bursts; ARTEMIS; muon telescope), technical developments (11m telescope: dedication and performance; 10m mount control; CCD cameras; light cones; filters; GRANITE upgrade; trigger configuration; miror coatings; lightning protection), data analysis (quick look; optical disk archive; false source method), infrastructure, and reviews.

  8. Unidirectional perfect absorber

    PubMed Central

    Jin, L.; Wang, P.; Song, Z.

    2016-01-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices. PMID:27615125

  9. Unidirectional perfect absorber

    NASA Astrophysics Data System (ADS)

    Jin, L.; Wang, P.; Song, Z.

    2016-09-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices.

  10. Unidirectional perfect absorber.

    PubMed

    Jin, L; Wang, P; Song, Z

    2016-01-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices. PMID:27615125

  11. Mechanical energy absorber

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J. (Inventor)

    1993-01-01

    An energy absorbing system for controlling the force where a moving object engages a stationary stop and where the system utilized telescopic tubular members, energy absorbing diaphragm elements, force regulating disc springs, and a return spring to return the telescoping member to its start position after stroking is presented. The energy absorbing system has frusto-conical diaphragm elements frictionally engaging the shaft and are opposed by a force regulating set of disc springs. In principle, this force feedback mechanism serves to keep the stroking load at a reasonable level even if the friction coefficient increases greatly. This force feedback device also serves to desensitize the singular and combined effects of manufacturing tolerances, sliding surface wear, temperature changes, dynamic effects, and lubricity.

  12. Unidirectional perfect absorber.

    PubMed

    Jin, L; Wang, P; Song, Z

    2016-09-12

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices.

  13. Measurements of indoor gamma radiation and radon concentrations in dwellings of Riyadh city, Saudi Arabia.

    PubMed

    Al-Saleh, Ferdoas S

    2007-07-01

    Indoor gamma radiation measurement at dwellings of Riyadh city in Saudi Arabia using TLD has been performed. Measurements were carried out from October 2004 to June 2005. The city was divided into five sectors, for four categories of bed rooms, living rooms, bathrooms and kitchens. The indoor gamma annual absorbed dose of Riyadh city is in the range from 303+/-57 to 700+/-38microGyy(-1) with an average value of 455.1+/-45microGyy(-1). The calculated corresponding annual effective dose to the adult population of the locations will vary from 212+/-40 to 490+/-27microSvy(-1) with an average value of 318.57+/-31microSvy(-1).(222)Rn concentration was measured at dwellings of Riyadh city in Saudi Arabia to estimate effective annual dose to the public from (222)Rn and its progeny. The (222)Rn concentrations were measured using CR-39 detector. The range of annual mean (222)Rn concentrations for all sites was 2-69Bqm(-3) with an average of 18.4Bqm(-3). The effective annual dose was estimated to be 0.46mSvy(-1).

  14. Neutron Absorbing Alloys

    DOEpatents

    Mizia, Ronald E.; Shaber, Eric L.; DuPont, John N.; Robino, Charles V.; Williams, David B.

    2004-05-04

    The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

  15. Solar concentrator/absorber

    NASA Technical Reports Server (NTRS)

    Von Tiesenhausen, G. F.

    1976-01-01

    Collector/energy converter, consisting of dual-slope optical concentrator and counterflow thermal energy absorber, is attached to multiaxis support structure. Efficient over wide range of illumination levels, device may be used to generate high temperature steam, serve as solar powered dryer, or power absorption cycle cooler.

  16. Metasurface Broadband Solar Absorber

    PubMed Central

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. PMID:26828999

  17. Metasurface Broadband Solar Absorber.

    PubMed

    Azad, Abul K; Kort-Kamp, Wilton J M; Sykora, Milan; Weisse-Bernstein, Nina R; Luk, Ting S; Taylor, Antoinette J; Dalvit, Diego A R; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.

  18. Metasurface Broadband Solar Absorber

    DOE PAGES

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-02-01

    Here, we demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Moreover, our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributionsmore » to elucidate how the absorption occurs within the metasurface structure.« less

  19. Metasurface Broadband Solar Absorber.

    PubMed

    Azad, Abul K; Kort-Kamp, Wilton J M; Sykora, Milan; Weisse-Bernstein, Nina R; Luk, Ting S; Taylor, Antoinette J; Dalvit, Diego A R; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. PMID:26828999

  20. Absorbed dose water calorimeter

    SciTech Connect

    Domen, S.R.

    1982-01-26

    An absorbed dose water calorimeter that takes advantage of the low thermal diffusivity of water and the water-imperviousness of polyethylene film. An ultra-small bead thermistor is sandwiched between two thin polyethylene films stretched between insulative supports in a water bath. The polyethylene films insulate the thermistor and its leads, the leads being run out from between the films in insulated sleeving and then to junctions to form a wheatstone bridge circuit. Convection barriers may be provided to reduce the effects of convection from the point of measurement. Controlled heating of different levels in the water bath is accomplished by electrical heater circuits provided for controlling temperature drift and providing adiabatic operation of the calorimeter. The absorbed dose is determined from the known specific heat of water and the measured temperature change.

  1. Ionized Absorbers in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, S.

    1999-01-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  2. Absorbed fractions for electrons in ellipsoidal volumes.

    PubMed

    Amato, E; Lizio, D; Baldari, S

    2011-01-21

    We applied a Monte Carlo simulation in Geant4 in order to calculate the absorbed fractions for monoenergetic electrons in the energy interval between 10 keV and 2 MeV, uniformly distributed in ellipsoids made from soft tissue. For each volume, we simulated a spherical shape, four oblate and four prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found, and the dependence of the fit parameters from electron energy is discussed and fitted by proper parametric functions. With the proposed formulation, the absorbed fraction for electrons in the 10-2000 keV energy range can be calculated for all volumes and for every ellipsoidal shape of practical interest. This method can be directly applied to evaluation of the absorbed fraction from the radionuclide emission of monoenergetic electrons, such as Auger or conversion electrons. The average deposited energy per disintegration in the case of extended beta spectra can be evaluated through integration. Two examples of application to a pure beta emitter such as (90)Y and to (131)I, whose emission include monoenergetic and beta electrons plus gamma photons, are presented. This approach represent a generalization of our previous studies, allowing a comprehensive treatment of absorbed fractions from electron and photon sources uniformly distributed in ellipsoidal volumes of any ellipticity and volume, in the whole range of practical interest for internal dosimetry in nuclear medicine applications, as well as in radiological protection estimations of doses from an internal contamination.

  3. Absorbed fractions for electrons in ellipsoidal volumes

    NASA Astrophysics Data System (ADS)

    Amato, E.; Lizio, D.; Baldari, S.

    2011-01-01

    We applied a Monte Carlo simulation in Geant4 in order to calculate the absorbed fractions for monoenergetic electrons in the energy interval between 10 keV and 2 MeV, uniformly distributed in ellipsoids made from soft tissue. For each volume, we simulated a spherical shape, four oblate and four prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found, and the dependence of the fit parameters from electron energy is discussed and fitted by proper parametric functions. With the proposed formulation, the absorbed fraction for electrons in the 10-2000 keV energy range can be calculated for all volumes and for every ellipsoidal shape of practical interest. This method can be directly applied to evaluation of the absorbed fraction from the radionuclide emission of monoenergetic electrons, such as Auger or conversion electrons. The average deposited energy per disintegration in the case of extended beta spectra can be evaluated through integration. Two examples of application to a pure beta emitter such as 90Y and to 131I, whose emission include monoenergetic and beta electrons plus gamma photons, are presented. This approach represent a generalization of our previous studies, allowing a comprehensive treatment of absorbed fractions from electron and photon sources uniformly distributed in ellipsoidal volumes of any ellipticity and volume, in the whole range of practical interest for internal dosimetry in nuclear medicine applications, as well as in radiological protection estimations of doses from an internal contamination.

  4. Absorber for terahertz radiation management

    DOEpatents

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

    2015-12-08

    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  5. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2013-11-12

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  6. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan; Farmer, Joseph C.; Lee, Chuck K.; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  7. Underwater acoustic omnidirectional absorber

    NASA Astrophysics Data System (ADS)

    Naify, Christina J.; Martin, Theodore P.; Layman, Christopher N.; Nicholas, Michael; Thangawng, Abel L.; Calvo, David C.; Orris, Gregory J.

    2014-02-01

    Gradient index media, which are designed by varying local element properties in given geometry, have been utilized to manipulate acoustic waves for a variety of devices. This study presents a cylindrical, two-dimensional acoustic "black hole" design that functions as an omnidirectional absorber for underwater applications. The design features a metamaterial shell that focuses acoustic energy into the shell's core. Multiple scattering theory was used to design layers of rubber cylinders with varying filling fractions to produce a linearly graded sound speed profile through the structure. Measured pressure intensity agreed with predicted results over a range of frequencies within the homogenization limit.

  8. Solar radiation absorbing material

    DOEpatents

    Googin, John M.; Schmitt, Charles R.; Schreyer, James M.; Whitehead, Harlan D.

    1977-01-01

    Solar energy absorbing means in solar collectors are provided by a solar selective carbon surface. A solar selective carbon surface is a microporous carbon surface having pores within the range of 0.2 to 2 micrometers. Such a surface is provided in a microporous carbon article by controlling the pore size. A thermally conductive substrate is provided with a solar selective surface by adhering an array of carbon particles in a suitable binder to the substrate, a majority of said particles having diameters within the range of about 0.2-10 microns.

  9. Statistics of the doses absorbed by workers

    NASA Astrophysics Data System (ADS)

    Parisi, A.

    1982-10-01

    A statistical analysis of the distribution of the doses by individual workers is presented to assess existing norms. A log-normal distribution is assumed for the individual doses. A reference distribution is introduced, characterized by log-normal distribution of annual doses, average 0,5 rem (10% of the limit) and 0.1% of the individuals that will absorb more than 5 rem. Expressions are given for the probability of finding a dose in a given interval and for the fraction of the collective dose due to doses from a given interval. An example using data from medical professions in the United States shows that the fraction of workers with annual doses larger than 5 rem is not contained within the 0.1% recommended limit, and that the level of risk is not uniform between professions.

  10. Liquid Cryogen Absorber for MICE

    SciTech Connect

    Baynham, D.E.; Bish, P.; Bradshaw, T.W.; Cummings, M.A.; Green,M.A.; Ishimoto, S.; Ivaniouchenkov, I.; Lau, W.; Yang, S.Q.; Zisman, M.S.

    2005-08-20

    The Muon Ionization Cooling Experiment (MICE) will test ionization cooling of muons. In order to have effective ionization cooling, one must use an absorber that is made from a low-z material. The most effective low z materials for ionization cooling are hydrogen, helium, lithium hydride, lithium and beryllium, in that order. In order to measure the effect of material on cooling, several absorber materials must be used. This report describes a liquid-hydrogen absorber that is within a pair of superconducting focusing solenoids. The absorber must also be suitable for use with liquid helium. The following absorber components are discussed in this report; the absorber body, its heat exchanger, the hydrogen system, and the hydrogen safety. Absorber cooling and the thin windows are not discussed here.

  11. Dual broadband metamaterial absorber.

    PubMed

    Kim, Young Ju; Yoo, Young Joon; Kim, Ki Won; Rhee, Joo Yull; Kim, Yong Hwan; Lee, YoungPak

    2015-02-23

    We propose polarization-independent and dual-broadband metamaterial absorbers at microwave frequencies. This is a periodic meta-atom array consisting of metal-dielectric-multilayer truncated cones. We demonstrate not only one broadband absorption from the fundamental magnetic resonances but additional broadband absorption in high-frequency range using the third-harmonic resonance, by both simulation and experiment. In simulation, the absorption was over 90% in 3.93-6.05 GHz, and 11.64-14.55 GHz. The corresponding experimental absorption bands over 90% were 3.88-6.08 GHz, 9.95-10.46 GHz and 11.86-13.84 GHz, respectively. The origin of absorption bands was elucidated. Furthermore, it is independent of polarization angle owing to the multilayered circular structures. The design is scalable to smaller size for the infrared and the visible ranges.

  12. Absorber coatings' degradation

    SciTech Connect

    Moore, S.W.

    1984-01-01

    This report is intended to document some of the Los Alamos efforts that have been carried out under the Department of Energy (DOE) Active Heating and Cooling Materials Reliability, Maintainability, and Exposure Testing program. Funding for these activities is obtained directly from DOE although they represent a variety of projects and coordination with other agencies. Major limitations to the use of solar energy are the uncertain reliability and lifetimes of solar systems. This program is aimed at determining material operating limitations, durabilities, and failure modes such that materials improvements can be made and lifetimes can be extended. Although many active and passive materials and systems are being studied at Los Alamos, this paper will concentrate on absorber coatings and degradation of these coatings.

  13. Shuttle flight test of an advanced gamma-ray detection system. Semi-annual technical report, 1 July-31 December 1983

    SciTech Connect

    Rester, A.C.

    1984-02-28

    In August of 1983 the Gamma-Ray Advanced Detector (GRAD) Project was assigned to the AFP-675 Program for flight on a future space-shuttle mission. In order to adapt the experiment to the requirements of AFP-675, a number of changes were made both in hardware and software. However, the necessity for such changes is more than affected by an expansion in scope of the experiment made possible by the introduction of a Payload Specialist into the operation. The principal changes to be made are in the avionics, as GRAD was originally designed for operation through ground-based telemetry. This complete redesigning of our avionics to accomodate operation by a Payload Specialist from the aft flight deck of the Orbiter allows us to take advantage of very recent findings on radiation-induced microprocessor failure in other space shuttle experiments in order to make the GRAD avionics less vulnerable to such latch-ups. Advances in bismuth germanate (BGO) scintillator technology during the year since construction of the prototype GRAD now make it possible to construct a BGO shield with a closed-ended geometry. This improvement will enhance the signal-to-noise ratio. In addition, a new type of decay-vetoed calibration probe using an alpha-rather than a beta-emitting radioactive source is being investigated.

  14. Broadband patterned magnetic microwave absorber

    SciTech Connect

    Li, Wei; Wu, Tianlong; Wang, Wei; Guan, Jianguo; Zhai, Pengcheng

    2014-07-28

    It is a tough task to greatly improve the working bandwidth for the traditional flat microwave absorbers because of the restriction of available material parameters. In this work, a simple patterning method is proposed to drastically broaden the absorption bandwidth of a conventional magnetic absorber. As a demonstration, an ultra-broadband microwave absorber with more than 90% absorption in the frequency range of 4–40 GHz is designed and experimentally realized, which has a thin thickness of 3.7 mm and a light weight equivalent to a 2-mm-thick flat absorber. In such a patterned absorber, the broadband strong absorption is mainly originated from the simultaneous incorporation of multiple λ/4 resonances and edge diffraction effects. This work provides a facile route to greatly extend the microwave absorption bandwidth for the currently available absorbing materials.

  15. Liquid Hydrogen Absorber for MICE

    SciTech Connect

    Ishimoto, S.; Suzuki, S.; Yoshida, M.; Green, Michael A.; Kuno, Y.; Lau, Wing

    2010-05-30

    Liquid hydrogen absorbers for the Muon Ionization Cooling Experiment (MICE) have been developed, and the first absorber has been tested at KEK. In the preliminary test at KEK we have successfully filled the absorber with {approx}2 liters of liquid hydrogen. The measured hydrogen condensation speed was 2.5 liters/day at 1.0 bar. No hydrogen leakage to vacuum was found between 300 K and 20 K. The MICE experiment includes three AFC (absorber focusing coil) modules, each containing a 21 liter liquid hydrogen absorber made of aluminum. The AFC module has safety windows to separate its vacuum from that of neighboring modules. Liquid hydrogen is supplied from a cryocooler with cooling power 1.5 W at 4.2 K. The first absorber will be assembled in the AFC module and installed in MICE at RAL.

  16. Electrochemically regenerable carbon dioxide absorber

    NASA Technical Reports Server (NTRS)

    Woods, R. R.; Marshall, R. D.; Schubert, F. H.; Heppner, D. B.

    1979-01-01

    Preliminary designs were generated for two electrochemically regenerable carbon dioxide absorber concepts. Initially, an electrochemically regenerable absorption bed concept was designed. This concept incorporated the required electrochemical regeneration components in the absorber design, permitting the absorbent to be regenerated within the absorption bed. This hardware was identified as the electrochemical absorber hardware. The second hardware concept separated the functional components of the regeneration and absorption process. This design approach minimized the extravehicular activity component volume by eliminating regeneration hardware components within the absorber. The electrochemical absorber hardware was extensively characterized for major operating parameters such as inlet carbon dioxide partial pressure, process air flow rate, operational pressure, inlet relative humidity, regeneration current density and absorption/regeneration cycle endurance testing.

  17. The changes in optical absorbance of ZrO2 thin film with the rise of the absorbed dose

    NASA Astrophysics Data System (ADS)

    Abayli, D.; Baydogan, N.

    2016-03-01

    In this study, zirconium oxide (ZrO2) thin film samples prepared by sol-gel method were irradiated using Co-60 radioisotope as gamma source. Then, it was investigated the ionizing effect on optical properties of ZrO2 thin film samples with the rise of the absorbed dose. The changes in the optical absorbance of ZrO2 thin films were determined by using optical transmittance and the reflectance measurements in the range between 190 - 1100 nm obtained from PG Instruments T80 UV-Vis spectrophotometer.

  18. Plants absorb heavy metals

    SciTech Connect

    Parry, J.

    1995-02-01

    Decontamination of heavy metals-polluted soils remains one of the most intractable problems of cleanup technology. Currently available techniques include extraction of the metals by physical and chemical means, such as acid leaching and electroosmosis, or immobilization by vitrification. There are presently no techniques for cleanup which are low cost and retain soil fertility after metals removal. But a solution to the problem could be on the horizon. A small but growing number of plants native to metalliferous soils are known to be capable of accumulating extremely high concentrations of metals in their aboveground portions. These hyperaccumulators, as they are called, contain up to 1,000 times larger metal concentrations in their aboveground parts than normal species. Their distribution is global, including many different families of flowering plants of varying growth forms, from herbaceous plants to trees. Hyperaccumulators absorb metals they do not need for their own nutrition. The metals are accumulated in the leaf and stem vacuoles, and to a lesser extent in the roots.

  19. Environmental gamma radiation measurement in district Swat, Pakistan.

    PubMed

    Jabbar, T; Khan, K; Subhani, M S; Akhter, P; Jabbar, A

    2008-01-01

    External exposure to environmental gamma ray sources is an important component of exposure to the public. A survey was carried out to determine activity concentration levels and associated doses from (226)Ra, (232)Th, (40)K and (137)Cs by means of high-resolution gamma ray spectrometry in the Swat district, famous for tourism. The mean concentrations for (226)Ra, (232)Th and (40)K were found to be 50.4 +/- 0.7, 34.8 +/- 0.7 and 434.5 +/- 7.4 Bq kg(-1), respectively, in soil samples, which are slightly more than the world average values. However, (137)Cs was only found in the soil sample of Barikot with an activity concentration of 34 +/- 1.2 Bq kg(-1). Only (40)K was determined in vegetation samples with an average activity of 172.2 +/- 1.7 Bq kg(-1), whereas in water samples, all radionuclides were found below lower limits of detection. The radium equivalent activity in all soil samples is lower than the limit set in the Organisation for Economic Cooperation and Development report (370 Bq kg(-1)). The value of the external exposure dose has been determined from the content of these radionuclides in soil. The average terrestrial gamma air absorbed dose rate was observed to be 62.4 nGy h(-1), which yields an annual effective dose of 0.08 mSv. The average value of the annual effective dose lies close to the global range of outdoor radiation exposure given in United Nations Scientific Committee on the Effects of Atomic Radiation. However, the main component of the radiation dose to the population residing in the study area arises from cosmic ray due to high altitude. PMID:18936087

  20. Leaf absorbance and photosynthesis

    NASA Technical Reports Server (NTRS)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  1. Hydraulic shock absorber

    SciTech Connect

    Tanaka, T.

    1987-03-03

    This patent describes a hydraulic shock absorber including a piston reciprocating in a cylinder, a piston upper chamber and a piston lower chamber which are oil-tightly separated by the piston, piston ports formed through the piston in a circle for communicating the piston upper chamber with the piston lower chamber, and return ports formed outside of the piston ports in a circle for communicating the piston upper chamber with the piston lower chamber. It also includes a sheet ring-like non-return valve provided above the piston and fitted to a piston rod, valve holes formed through the non-return valve in opposed relation with the piston ports. A ring-like non-return valve stopper fixed to the piston rod on an upper side of the non-return valve with a small spaced defined between the non-return valve and the non-return valve stopper, and a spring is interposed between the non-return valve and the non-return valve stopper for normally urging the non-return valve to an upper surface of the piston. Movement of the piston to the piston upper chamber allows oil to flow from the piston upper chamber through the piston ports to the piston lower chamber, while the return ports are closed by the non-return valve to generate a vibration damping force by resistance upon pass of the oil through the piston parts. The improvement described here comprises a groove formed in an upper surface of the piston facing the non-return valve and aligned with the valve holes, the groove being in the circle where the piston ports lie and being in communication with the piston ports.

  2. Metal-shearing energy absorber

    NASA Technical Reports Server (NTRS)

    Fay, R. J.; Wittrock, E. P.

    1971-01-01

    Device, consisting of tongue of thin aluminum alloy strip, pull tab, slotted steel plate which serves as cutter, and steel buckle, absorbs mechanical energy when its ends are subjected to tensile loading. Device is applicable as auxiliary shock absorbing anchor for automobile and airplane safety belts.

  3. The broadband dynamic vibration absorber

    NASA Astrophysics Data System (ADS)

    Hunt, J. B.; Nissen, J.-C.

    1982-08-01

    The limited effectiveness of the linear passive dynamic vibration absorber is described. This is followed by an analysis producing the response of a primary system when a non-linear softening Belleville spring is used in the absorber. It is shown that the suppression bandwidth can be doubled by this means.

  4. 30 CFR 57.5047 - Gamma radiation surveys.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Gamma radiation surveys. 57.5047 Section 57..., Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047 Gamma radiation surveys. (a) Gamma radiation surveys shall be conducted annually in all underground mines...

  5. 30 CFR 57.5047 - Gamma radiation surveys.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Gamma radiation surveys. 57.5047 Section 57..., Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047 Gamma radiation surveys. (a) Gamma radiation surveys shall be conducted annually in all underground mines...

  6. 30 CFR 57.5047 - Gamma radiation surveys.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Gamma radiation surveys. 57.5047 Section 57..., Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047 Gamma radiation surveys. (a) Gamma radiation surveys shall be conducted annually in all underground mines...

  7. 30 CFR 57.5047 - Gamma radiation surveys.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Gamma radiation surveys. 57.5047 Section 57..., Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047 Gamma radiation surveys. (a) Gamma radiation surveys shall be conducted annually in all underground mines...

  8. 30 CFR 57.5047 - Gamma radiation surveys.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Gamma radiation surveys. 57.5047 Section 57..., Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047 Gamma radiation surveys. (a) Gamma radiation surveys shall be conducted annually in all underground mines...

  9. Absorbent product to absorb fluids. [for collection of human wastes

    NASA Technical Reports Server (NTRS)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multi-layer absorbent product for use in contact with the skin to absorb fluids is discussed. The product utilizes a water pervious facing layer for contacting the skin, overlayed by a first fibrous wicking layer, the wicking layer preferably being of the one-way variety in which fluid or liquid is moved away from the facing layer. The product further includes a first container section defined by inner and outer layer of a water pervious wicking material between which is disposed a first absorbent mass. A second container section defined by inner and outer layers between which is disposed a second absorbent mass and a liquid impermeable/gas permeable layer. Spacesuit applications are discussed.

  10. Self-Regulating Shock Absorber

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J.

    1995-01-01

    Mechanical shock absorber keeps frictional damping force within tolerable limit. Its damping force does not increase with coefficient of friction between energy-absorbing components; rather, frictional damping force varies only slightly. Relatively insensitive to manufacturing variations and environmental conditions altering friction. Does not exhibit high breakaway friction and consequent sharp increase followed by sharp decrease in damping force at beginning of stroking. Damping force in absorber does not vary appreciably with speed of stroking. In addition, not vulnerable to leakage of hydraulic fluid.

  11. Countercurrent flow absorber and desorber

    DOEpatents

    Wilkinson, William H.

    1984-01-01

    Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system.

  12. Countercurrent flow absorber and desorber

    DOEpatents

    Wilkinson, W.H.

    1984-10-16

    Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system. 9 figs.

  13. Carbon Absorber Retrofit Equipment (CARE)

    SciTech Connect

    Klein, Eric

    2015-12-23

    During Project DE-FE0007528, CARE (Carbon Absorber Retrofit Equipment), Neumann Systems Group (NSG) designed, installed and tested a 0.5MW NeuStream® carbon dioxide (CO2) capture system using the patented NeuStream® absorber equipment and concentrated (6 molal) piperazine (PZ) as the solvent at Colorado Springs Utilities’ (CSU’s) Martin Drake pulverized coal (PC) power plant. The 36 month project included design, build and test phases. The 0.5MW NeuStream® CO2 capture system was successfully tested on flue gas from both coal and natural gas combustion sources and was shown to meet project objectives. Ninety percent CO2 removal was achieved with greater than 95% CO2product purity. The absorbers tested support a 90% reduction in absorber volume compared to packed towers and with an absorber parasitic power of less than 1% when configured for operation with a 550MW coal plant. The preliminary techno-economic analysis (TEA) performed by the Energy and Environmental Research Center (EERC) predicted an over-the-fence cost of $25.73/tonne of CO2 captured from a sub-critical PC plant.

  14. Mushroom plasmonic metamaterial infrared absorbers

    NASA Astrophysics Data System (ADS)

    Ogawa, Shinpei; Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-01

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF2 etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  15. Additive manufacturing of RF absorbers

    NASA Astrophysics Data System (ADS)

    Mills, Matthew S.

    The ability of additive manufacturing techniques to fabricate integrated electromagnetic absorbers tuned for specific radio frequency bands within structural composites allows for unique combinations of mechanical and electromagnetic properties. These composites and films can be used for RF shielding of sensitive electromagnetic components through in-plane and out-of-plane RF absorption. Structural composites are a common building block of many commercial platforms. These platforms may be placed in situations in which there is a need for embedded RF absorbing properties along with structural properties. Instead of adding radar absorbing treatments to the external surface of existing structures, which adds increased size, weight and cost; it could prove to be advantageous to integrate the microwave absorbing properties directly into the composite during the fabrication process. In this thesis, a method based on additive manufacturing techniques of composites structures with prescribed electromagnetic loss, within the frequency range 1 to 26GHz, is presented. This method utilizes screen printing and nScrypt micro dispensing to pattern a carbon based ink onto low loss substrates. The materials chosen for this study will be presented, and the fabrication technique that these materials went through to create RF absorbing structures will be described. The calibration methods used, the modeling of the RF structures, and the applications in which this technology can be utilized will also be presented.

  16. Mushroom plasmonic metamaterial infrared absorbers

    SciTech Connect

    Ogawa, Shinpei Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-26

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF{sub 2} etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  17. Nonventing, Regenerable, Lightweight Heat Absorber

    NASA Technical Reports Server (NTRS)

    Izenson, Michael G.; Chen, Weibo

    2008-01-01

    A lightweight, regenerable heat absorber (RHA), developed for rejecting metabolic heat from a space suit, may also be useful on Earth for short-term cooling of heavy protective garments. Unlike prior space-suit-cooling systems, a system that includes this RHA does not vent water. The closed system contains water reservoirs, tubes through which water is circulated to absorb heat, an evaporator, and an absorber/radiator. The radiator includes a solution of LiCl contained in a porous material in titanium tubes. The evaporator cools water that circulates through a liquid-cooled garment. Water vapor produced in the evaporator enters the radiator tubes where it is absorbed into the LiCl solution, releasing heat. Much of the heat of absorption is rejected to the environment via the radiator. After use, the RHA is regenerated by heating it to a temperature of 100 C for about 2 hours to drive the absorbed water back to the evaporator. A system including a prototype of the RHA was found to be capable of maintaining a temperature of 20 C while removing heat at a rate of 200 W for 6 hours.

  18. Damage tolerant light absorbing material

    DOEpatents

    Lauf, Robert J.; Hamby, Jr., Clyde; Akerman, M. Alfred; Seals, Roland D.

    1993-01-01

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000.degree. C. to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm.sup.3.

  19. Damage tolerant light absorbing material

    DOEpatents

    Lauf, R.J.; Hamby, C. Jr.; Akerman, M.A.; Seals, R.D.

    1993-09-07

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, is prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000 C to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm[sup 3]. 9 figures.

  20. Waveform-Dependent Absorbing Metasurfaces

    NASA Astrophysics Data System (ADS)

    Wakatsuchi, Hiroki; Kim, Sanghoon; Rushton, Jeremiah J.; Sievenpiper, Daniel F.

    2013-12-01

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high-power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high-power pulses but not for high-power continuous waves (CW’s), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e., CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.

  1. Oil and fat absorbing polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr. (Inventor)

    1977-01-01

    A method is described for forming a solid network polymer having a minimal amount of crosslinking for use in absorbing fats and oils. The polymer remains solid at a swelling ratio in oil or fat of at least ten and provides an oil absorption greater than 900 weight percent.

  2. Counterflow absorber for an absorption refrigeration system

    DOEpatents

    Reimann, Robert C.

    1984-01-01

    An air-cooled, vertical tube absorber for an absorption refrigeration system is disclosed. Strong absorbent solution is supplied to the top of the absorber and refrigerant vapor is supplied to the bottom of the absorber to create a direct counterflow of refrigerant vapor and absorbent solution in the absorber. The refrigeration system is designed so that the volume flow rate of refrigerant vapor in the tubes of the absorber is sufficient to create a substantially direct counterflow along the entire length of each tube in the absorber. This provides several advantages for the absorber such as higher efficiency and improved heat transfer characteristics, and allows improved purging of non-condensibles from the absorber.

  3. Natural radioactivity and gamma dose from Sri Lankan clay bricks used in building construction.

    PubMed

    Hewamanna, R; Sumithrarachchi, C S; Mahawatte, P; Nanayakkara, H L; Ratnayake, H C

    2001-02-01

    The specific radioactivity concentrations of 226Ra, 232Th and 40K have been determined by gamma ray spectrometry with an HPGe detector in clay brick samples from kiln sites located in 17 towns. The average values of the measured activities are 35, 72, and 585 Bq kg(-1), respectively, for the above radionuclides. The average estimated radium equivalent concentration is 183 Bq kg(-1) and is comparable with reported values for many countries in the world. This value and the value obtained from the criteria formula suggest that the use of local clay bricks do not pose a radiological hazard. The calculated average absorbed dose rate in air within buildings was found to be 102 nGy h(-1) while the population weighted indoor annual effective dose was 0.20 mSv.

  4. Radiometric analysis of construction materials using HPGe gamma-ray spectrometry.

    PubMed

    Khandaker, M U; Jojo, P J; Kassim, H A; Amin, Y M

    2012-11-01

    Concentrations of primordial radionuclides in common construction materials collected from the south-west coastal region of India were determined using a high-purity germanium gamma-ray spectrometer. Average specific activities (Bq kg(-1)) for (238)U((226)Ra) in cement, brick, soil and stone samples were obtained as 54 ± 13, 21 ± 4, 50 ± 12 and 46 ± 8, respectively. Respective values of (232)Th were obtained as 65 ± 10, 21 ± 3, 58 ± 10 and 57 ± 12. Concentrations of (40)K radionuclide in cement, brick, soil and stone samples were found to be 440 ± 91, 290 ± 20, 380 ± 61 and 432 ± 64, respectively. To evaluate the radiological hazards, radium equivalent activity, various hazard indices, absorbed dose rate and annual effective dose have been calculated, and compared with the literature values. Obtained data could be used as reference information to assess any radiological contamination due to construction materials in future.

  5. A Monte Carlo evaluation of three Compton camera absorbers.

    PubMed

    Uche, C Z; Round, W H; Cree, M J

    2011-09-01

    We present a quantitative study on the performance of cadmium zinc telluride (CZT), thallium-doped sodium iodide (NaI(Tl)) and germanium (Ge) detectors as potential Compton camera absorbers. The GEANT4 toolkit was used to model the performance of these materials over the nuclear medicine energy range. CZT and Ge demonstrate the highest and lowest efficiencies respectively. Although the best spatial resolution was attained for Ge, its lowest ratio of single photoelectric to multiple interactions suggests that it is most prone to inter-pixel cross-talk. In contrast, CZT, which demonstrates the least positioning error due to multiple interactions, has a comparable spatial resolution with Ge. Therefore, we modelled a Compton camera system based on silicon (Si) and CZT as the scatterer and absorber respectively. The effects of the detector parameters of our proposed system on image resolution were evaluated and our results show good agreement with previous studies. Interestingly, spatial resolution which accounted for the least image degradation at 140.5 keV became the dominant degrading factor at 511 keV, indicating that the absorber parameters play some key roles at higher energies. The results of this study have validated the predictions by An et al. which state that the use of a higher energy gamma source together with reduction of the absorber segmentation to sub-millimetre could achieve the image resolution of 5 mm required in medical imaging.

  6. Gamma Knife

    MedlinePlus

    ... results are sent to the Gamma Knife®'s planning computer system. Together, physicians ( radiation oncologists and neurosurgeons) and medical physicists delineate targets and normal anatomical structures. They use a planning computer program to determine the exact spatial relationship between ...

  7. Gamma watermarking

    DOEpatents

    Ishikawa, Muriel Y.; Wood, Lowell L.; Lougheed, Ronald W.; Moody, Kenton J.; Wang, Tzu-Fang

    2004-05-25

    A covert, gamma-ray "signature" is used as a "watermark" for property identification. This new watermarking technology is based on a unique steganographic or "hidden writing" digital signature, implemented in tiny quantities of gamma-ray-emitting radioisotopic material combinations, generally covertly emplaced on or within an object. This digital signature may be readily recovered at distant future times, by placing a sensitive, high energy-resolution gamma-ray detecting instrument reasonably precisely over the location of the watermark, which location may be known only to the object's owner; however, the signature is concealed from all ordinary detection means because its exceedingly low level of activity is obscured by the natural radiation background (including the gamma radiation naturally emanating from the object itself, from cosmic radiation and material surroundings, from human bodies, etc.). The "watermark" is used in object-tagging for establishing object identity, history or ownership. It thus may serve as an aid to law enforcement officials in identifying stolen property and prosecuting theft thereof. Highly effective, potentially very low cost identification-on demand of items of most all types is thus made possible.

  8. Digital Alloy Absorber for Photodetectors

    NASA Technical Reports Server (NTRS)

    Hill, Cory J. (Inventor); Ting, David Z. (Inventor); Gunapala, Sarath D. (Inventor)

    2016-01-01

    In order to increase the spectral response range and improve the mobility of the photo-generated carriers (e.g. in an nBn photodetector), a digital alloy absorber may be employed by embedding one (or fraction thereof) to several monolayers of a semiconductor material (insert layers) periodically into a different host semiconductor material of the absorber layer. The semiconductor material of the insert layer and the host semiconductor materials may have lattice constants that are substantially mismatched. For example, this may performed by periodically embedding monolayers of InSb into an InAsSb host as the absorption region to extend the cutoff wavelength of InAsSb photodetectors, such as InAsSb based nBn devices. The described technique allows for simultaneous control of alloy composition and net strain, which are both key parameters for the photodetector operation.

  9. Energy-Absorbing, Lightweight Wheels

    NASA Technical Reports Server (NTRS)

    Waydo, Peter

    2003-01-01

    Improved energy-absorbing wheels are under development for use on special-purpose vehicles that must traverse rough terrain under conditions (e.g., extreme cold) in which rubber pneumatic tires would fail. The designs of these wheels differ from those of prior non-pneumatic energy-absorbing wheels in ways that result in lighter weights and more effective reduction of stresses generated by ground/wheel contact forces. These wheels could be made of metals and/or composite materials to withstand the expected extreme operating conditions. As shown in the figure, a wheel according to this concept would include an isogrid tire connected to a hub via spring rods. The isogrid tire would be a stiff, lightweight structure typically made of aluminum. The isogrid aspect of the structure would both impart stiffness and act as a traction surface. The hub would be a thin-walled body of revolution having a simple or compound conical or other shape chosen for structural efficiency. The spring rods would absorb energy and partially isolate the hub and the supported vehicle from impact loads. The general spring-rod configuration shown in the figure was chosen because it would distribute contact and impact loads nearly evenly around the periphery of the hub, thereby helping to protect the hub against damage that would otherwise be caused by large loads concentrated onto small portions of the hub.

  10. Absorbed dose rate in air in metropolitan Tokyo before the Fukushima Daiichi Nuclear Power Plant accident.

    PubMed

    Inoue, K; Hosoda, M; Fukushi, M; Furukawa, M; Tokonami, S

    2015-11-01

    The monitoring of absorbed dose rate in air has been carried out continually at various locations in metropolitan Tokyo after the accident of the Fukushima Daiichi Nuclear Power Plant. While the data obtained before the accident are needed to more accurately assess the effects of radionuclide contamination from the accident, detailed data for metropolitan Tokyo obtained before the accident have not been reported. A car-borne survey of the absorbed dose rate in air in metropolitan Tokyo was carried out during August to September 2003. The average absorbed dose rate in air in metropolitan Tokyo was 49±6 nGy h(-1). The absorbed dose rate in air in western Tokyo was higher compared with that in central Tokyo. Here, if the absorbed dose rate indoors in Tokyo is equivalent to that outdoors, the annual effective dose would be calculated as 0.32 mSv y(-1).

  11. Absorbed dose rate in air in metropolitan Tokyo before the Fukushima Daiichi Nuclear Power Plant accident.

    PubMed

    Inoue, K; Hosoda, M; Fukushi, M; Furukawa, M; Tokonami, S

    2015-11-01

    The monitoring of absorbed dose rate in air has been carried out continually at various locations in metropolitan Tokyo after the accident of the Fukushima Daiichi Nuclear Power Plant. While the data obtained before the accident are needed to more accurately assess the effects of radionuclide contamination from the accident, detailed data for metropolitan Tokyo obtained before the accident have not been reported. A car-borne survey of the absorbed dose rate in air in metropolitan Tokyo was carried out during August to September 2003. The average absorbed dose rate in air in metropolitan Tokyo was 49±6 nGy h(-1). The absorbed dose rate in air in western Tokyo was higher compared with that in central Tokyo. Here, if the absorbed dose rate indoors in Tokyo is equivalent to that outdoors, the annual effective dose would be calculated as 0.32 mSv y(-1). PMID:25944962

  12. Improving the laboratory monitoring of absorbent oil

    SciTech Connect

    V.S. Shved; S.S. Sychev; I.V. Safina; S.A. Klykov

    2009-05-15

    The performance of absorbent coal tar oil is analyzed as a function of the constituent and group composition. The qualitative and quantitative composition of the oil that ensures the required absorbent properties is determined. Operative monitoring may be based on absorbent characteristics that permit regulation of the beginning and end of regeneration.

  13. Porcelain enamel neutron absorbing material

    SciTech Connect

    Iverson, Daniel C.

    1990-01-01

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  14. Porcelain enamel neutron absorbing material

    SciTech Connect

    Iverson, Daniel C.

    1990-02-06

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  15. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, D.C.

    1987-11-20

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compound of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved. 2 figs.

  16. The Double Absorbing Boundary method

    NASA Astrophysics Data System (ADS)

    Hagstrom, Thomas; Givoli, Dan; Rabinovich, Daniel; Bielak, Jacobo

    2014-02-01

    A new approach is devised for solving wave problems in unbounded domains. It has common features to each of two types of existing techniques: local high-order Absorbing Boundary Conditions (ABC) and Perfectly Matched Layers (PML). However, it is different from both and enjoys relative advantages with respect to both. The new method, called the Double Absorbing Boundary (DAB) method, is based on truncating the unbounded domain to produce a finite computational domain Ω, and on applying a local high-order ABC on two parallel artificial boundaries, which are a small distance apart, and thus form a thin non-reflecting layer. Auxiliary variables are defined on the two boundaries and inside the layer bounded by them, and participate in the numerical scheme. The DAB method is first introduced in general terms, using the 2D scalar time-dependent wave equation as a model. Then it is applied to the 1D Klein-Gordon equation, using finite difference discretization in space and time, and to the 2D wave equation in a wave guide, using finite element discretization in space and dissipative time stepping. The computational aspects of the method are discussed, and numerical experiments demonstrate its performance.

  17. A polarization-independent broadband terahertz absorber

    SciTech Connect

    Shi, Cheng; Zang, XiaoFei E-mail: ymzhu@usst.edu.cn; Wang, YiQiao; Chen, Lin; Cai, Bin; Zhu, YiMing E-mail: ymzhu@usst.edu.cn

    2014-07-21

    A highly efficient broadband terahertz absorber is designed, fabricated, and experimentally as well as theoretically evaluated. The absorber comprises a heavily doped silicon substrate and a well-designed two-dimensional grating. Due to the destructive interference of waves and diffraction, the absorber can achieve over 95% absorption in a broad frequency range from 1 to 2 THz and for angles of incidence from 0° to 60°. Such a terahertz absorber is also polarization-independent due to its symmetrical structure. This omnidirectional and broadband absorber have potential applications in anti-reflection coatings, imaging systems, and so on.

  18. Stereotactic radiosurgery - Gamma Knife

    MedlinePlus

    ... Gamma Knife; Gamma Knife radiosurgery; Non-invasive neurosugery; Epilepsy - Gamma Knife ... problems ( arteriovenous malformation , arteriovenous fistula ) Some types of epilepsy Trigeminal neuralgia (severe nerve pain of the face) ...

  19. Evaluation of radioactive environmental hazards in Area-3, Northern Palmyrides, Central Syria using airborne spectrometric gamma technique.

    PubMed

    Asfahani, J; Aissa, M; Al-Hent, R

    2016-01-01

    Airborne spectrometric gamma data are used in this paper to estimate the degree of radioactive hazard on humanity in Area-3, Northern Palmyrides, Central Syria. Exposure Rate (ER), Absorbed Dose Rate (ADR), Annual Effective Dose Rate (AEDR), and Heat Production (HP) of the eleven radiometric units included in the established lithological scored map in the study area have been computed to evaluate the radiation background influence in humans. The results obtained indicate that a human body in Area-3 is subjected to radiation hazards in the acceptable limits for long duration exposure. The highest radiogenetic heat production values in Area-3 correspond to the phosphatic locations characterized by relatively high values of uranium and thorium. PMID:26569554

  20. Evaluation of radioactive environmental hazards in Area-3, Northern Palmyrides, Central Syria using airborne spectrometric gamma technique.

    PubMed

    Asfahani, J; Aissa, M; Al-Hent, R

    2016-01-01

    Airborne spectrometric gamma data are used in this paper to estimate the degree of radioactive hazard on humanity in Area-3, Northern Palmyrides, Central Syria. Exposure Rate (ER), Absorbed Dose Rate (ADR), Annual Effective Dose Rate (AEDR), and Heat Production (HP) of the eleven radiometric units included in the established lithological scored map in the study area have been computed to evaluate the radiation background influence in humans. The results obtained indicate that a human body in Area-3 is subjected to radiation hazards in the acceptable limits for long duration exposure. The highest radiogenetic heat production values in Area-3 correspond to the phosphatic locations characterized by relatively high values of uranium and thorium.

  1. Advanced radiation detector development: Advanced semiconductor detector development: Development of a room-temperature, gamma ray detector using gallium arsenide to develop an electrode detector. Annual progress report, September 30, 1994--September 29, 1995

    SciTech Connect

    Knoll, G.F.

    1995-11-01

    The advanced detector development project at the University of Michigan has completed the first full year of its current funding. The general goals are the development of radiation detectors and spectrometers that are capable of portable room temperature operation. Over the past 12 months, the authors have worked primarily in the development of semiconductor spectrometers with ``single carrier`` response that offer the promise of room temperature operation and good energy resolution in gamma ray spectroscopy. They have also begun a small scale effort at investigating the properties of a small non-spectroscopic detector system with directional characteristics that will allow identification of the approximate direction in which gamma rays are incident. These activities have made use of the extensive clean room facilities at the University of Michigan for semiconductor device fabrication, and also the radiation measurement capabilities provided in the laboratory in the Phoenix Building on the North Campus.

  2. Airborne Gamma-Spectrometry in Switzerland

    SciTech Connect

    Butterweck, Gernot; Bucher, Benno; Rybach, Ladislaus

    2008-08-07

    Airborne gamma-spectrometry is able to obtain fast radiological information over large areas. The airborne gamma-spectrometry unit deployed in Switzerland by the Swiss National Emergency Operations Centre (NEOC) consists of a Swiss army Super Puma helicopter equipped with four NaI-Detectors with a total volume of 17 liters, associated electronics and a real-time data evaluation and mapping unit developed by the Swiss Federal Institute of Technology (ETH) and the Paul Scherrer Institut (PSI). The operational readiness of the airborne gamma-spectrometry system is validated in annual exercises of one week duration. Data from 2005 and 2006 exercises are represented in maps of {sup 137}Cs activity concentration for two towns located in southern and western Switzerland. An indicator of man-made radioactivity (MMGC ratio) is demonstrated for an area with four different types of nuclear installations. The intercomparison between airborne gamma-spectrometry and ground measurements showed good agreement between both methods.

  3. Magnetic field effects on microwave absorbing materials

    NASA Technical Reports Server (NTRS)

    Goldberg, Ira; Hollingsworth, Charles S.; Mckinney, Ted M.

    1991-01-01

    The objective of this program was to gather information to formulate a microwave absorber that can work in the presence of strong constant direct current (DC) magnetic fields. The program was conducted in four steps. The first step was to investigate the electrical and magnetic properties of magnetic and ferrite microwave absorbers in the presence of strong magnetic fields. This included both experimental measurements and a literature survey of properties that may be applicable to finding an appropriate absorbing material. The second step was to identify those material properties that will produce desirable absorptive properties in the presence of intense magnetic fields and determine the range of magnetic field in which the absorbers remain effective. The third step was to establish ferrite absorber designs that will produce low reflection and adequate absorption in the presence of intense inhomogeneous static magnetic fields. The fourth and final step was to prepare and test samples of such magnetic microwave absorbers if such designs seem practical.

  4. TPX/TFTR Neutral Beam energy absorbers

    SciTech Connect

    Dahlgren, F.; Wright, K.; Kamperschroer, J.; Grisham, L.; Lontai, L.; Peters, C.; VonHalle, A.

    1993-11-01

    The present beam energy absorbing surfaces on the TFTR Neutral Beams such as Ion Dumps, Calorimeters, beam defining apertures, and scrapers, are simple water cooled copper plates which wee designed to absorb (via their thermal inertia) the incident beam power for two seconds with a five minute coal down interval between pulses. These components are not capable of absorbing the anticipated beam power loading for 1000 second TPX pulses and will have to be replaced with an actively cooled design. While several actively cooled energy absorbing designs were considered,, the hypervapotron elements currently being used on the JET beamlines were chosen due to their lower cooling water demands and reliable performance on JET.

  5. Absorbent product and articles made therefrom

    NASA Technical Reports Server (NTRS)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multilayer absorbent product for use in contact with the skin to absorb fluids is described. The product has a water pervious facing layer for contacting the skin, and a first fibrous wicking layer overlaying the water pervious layer. A first container section is defined by inner and outer layers of a water pervious wicking material in between a first absorbent mass and a second container section defined by inner and outer layers of a water pervious wicking material between what is disposed a second absorbent mass, and a liquid impermeable/gas permeable layer overlaying the second fibrous wicking layer.

  6. Advanced Reflector and Absorber Materials (Fact Sheet)

    SciTech Connect

    Not Available

    2010-08-01

    Fact sheet describing NREL CSP Program capabilities in the area of advanced reflector and absorber materials: evaluating performance, determining degradation rates and lifetime, and developing new coatings.

  7. Device for absorbing mechanical shock

    DOEpatents

    Newlon, Charles E.

    1980-01-01

    This invention is a comparatively inexpensive but efficient shock-absorbing device having special application to the protection of shipping and storage cylinders. In a typical application, two of the devices are strapped to a cylinder to serve as saddle-type supports for the cylinder during storage and to protect the cylinder in the event it is dropped during lifting or lowering operations. In its preferred form, the invention includes a hardwood plank whose grain runs in the longitudinal direction. The basal portion of the plank is of solid cross-section, whereas the upper face of the plank is cut away to form a concave surface fittable against the sidewall of a storage cylinder. The concave surface is divided into a series of segments by transversely extending, throughgoing relief slots. A layer of elastomeric material is positioned on the concave face, the elastomer being extrudable into slots when pressed against the segments by a preselected pressure characteristic of a high-energy impact. The compressive, tensile, and shear properties of the hardwood and the elastomer are utilized in combination to provide a surprisingly high energy-absorption capability.

  8. Device for absorbing mechanical shock

    DOEpatents

    Newlon, C.E.

    1979-08-29

    This invention is a comparatively inexpensive but efficient shock-absorbing device having special application to the protection of shipping and storage cylinders. In a typical application, two of the devices are strapped to a cylinder to serve as saddle-type supports for the cylinder during storage and to protect the cylinder in the event it is dropped during lifting or lowering operations. In its preferred form, the invention includes a hardwood plank whose grain runs in the longitudinal direction. The basal portion of the plank is of solid cross-section, whereas the upper face of the plank is cut away to form a concave surface fittable against the sidewall of a storage cylinder. The concave surface is divided into a series of segments by transversely extending, throughgoing relief slots. A layer of elastomeric material is positioned on the concave face, the elastomer being extrudable into slots when pressed against the segments by a preselected pressure characteristic of a high-energy impact. The compressive, tensile, and shear properties of the hardwood and the elastomer are utilized in combination to provide a surprisingly high energy-absorption capability.

  9. Gamma ray generator

    SciTech Connect

    Firestone, Richard B; Reijonen, Jani

    2014-05-27

    An embodiment of a gamma ray generator includes a neutron generator and a moderator. The moderator is coupled to the neutron generator. The moderator includes a neutron capture material. In operation, the neutron generator produces neutrons and the neutron capture material captures at least some of the neutrons to produces gamma rays. An application of the gamma ray generator is as a source of gamma rays for calibration of gamma ray detectors.

  10. An EPIC view of absorbed HMXBs in the Scutum Arm

    NASA Astrophysics Data System (ADS)

    Bodaghee, Arash

    2009-10-01

    Observations are proposed for 5 new unclassified gamma-ray sources in the Scutum Arm. Each source will be targeted by EPIC PN and MOS cameras for 25 ks providing us with: a refined position that will facilitate optical/IR identification; spectral characteristics including the slope of the power law in X-rays and the photoelectric absorption; and timing characteristics in the case of Galactic XRBs. The targets lie within 5degs of the plane of the Milky Way, towards the tangent to the Scutum Arm, and are expected to be Galactic in origin. The main objective is to elucidate the nature of these sources. An additional benefit is that we will have a more complete sample of high-energy emitters in the Scutum Arm to compare with absorbed HMXBs in the Norma Arm.

  11. Distributions of 12 elements on 64 absorbers from simulated Hanford Neutralized Current Acid Waste (NCAW)

    SciTech Connect

    Svitra, Z.V.; Bowen, S.M.; Marsh, S.F.

    1994-12-01

    As part of the Hanford Tank Waste Remediation System program at Los Alamos, we evaluated 64 commercially available or experimental absorber materials for their ability to remove hazardous components from high-level waste. These absorbers included cation and anion exchange resins, inorganic exchangers, composite absorbers, and a series of liquid extractants sorbed on porous support-beads. We tested these absorbers with a solution that simulates Hanford neutralized current acid waste (NCAW) (pH 14.2). To this simulant solution we added the appropriate radionuclides and used gamma spectrometry to measure fission products (Cs, Sr, Tc, and Y) and matrix elements (Cr, Co, Fe, Mn, Ni, V, Zn, and Zr). For each of 768 element/absorber combinations, we measured distribution coefficients for dynamic contact periods of 30 min, 2 h, and 6 h to obtain information about sorption kinetics. On the basis of these 2304 measured distribution coefficients, we determined that many of the tested absorbers may be suitable for processing NCAW solutions.

  12. Distributions of 15 elements on 58 absorbers from simulated Hanford Double-Shell Slurry Feed (DSSF)

    SciTech Connect

    Marsh, S.F.; Svitra, Z.V.; Bowen, S.M.

    1994-11-01

    As part of the Hanford Tank Waste Remediation System program at Los Alamos, we evaluated 58 commercially available or experimental absorber materials for their ability to remove hazardous components from high-level waste. These absorbers included cation and anion exchange resins, inorganic exchangers, composite absorbers, pillared layered materials, and a series of liquid extractants sorbed on porous support-beads. We tested these absorbers with a solution that simulates Hanford double-shell slurry feed (DSSF) (pH 14.0). To this simulant solution we added the appropriate radionuclides and used gamma spectrometry to measure fission products (Ce, Cs, Sr, Tc, and Y), actinides (U and Am), and matrix elements (Cr, Co, Fe, Mn, Ni, V, Zn, and Zr). For each of 870 element/absorber combinations, we measured distribution coefficients for dynamic contact periods of 30 min, 2 h, and 6 h to obtain information about sorption kinetics. On the basis of these 2610 measured distribution coefficients, we determined that many of the tested absorbers may be suitable for processing DSSF solutions.

  13. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6050 Saliva absorber. (a) Identification. A...

  14. Comments on liquid hydrogen absorbers for MICE

    SciTech Connect

    Green, Michael A.

    2003-02-01

    This report describes the heat transfer problems associatedwith a liquid hydrogen absorber for the MICE experiment. This reportdescribes a technique for modeling heat transfer from the outside world,to the abosrber case and in its vacuum vessel, to the hydrogen and theninto helium gas at 14 K. Also presented are the equation for freeconvection cooling of the liquid hydrogen in the absorber.

  15. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6050 Saliva absorber. (a) Identification. A...

  16. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6050 Saliva absorber. (a) Identification. A...

  17. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6050 Saliva absorber. (a) Identification. A...

  18. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6050 Saliva absorber. (a) Identification. A...

  19. Relativistic induced Compton scattering in synchrotron self-absorbed sources

    NASA Technical Reports Server (NTRS)

    Sincell, Mark W.; Krolik, Julian H.

    1994-01-01

    We present a model of the radio emission from synchrotron self-absorbed sources, including the effects of induced Compton scattering by the relativistic electrons in the source. Order of magnitude estimates show that stimulated scattering becomes the dominant absorption process when (kT(sub B)/m(sub e) c(exp 2))Tau(sub T) greater than or approximately 1.0. Numerical simulations demonstrate that relativistic induced Compton scattering limits the brightness temperature of a self-absorbed synchroton sources to T(sub B) less than or approximately 2 x 10(exp 11) nu(exp -1/p + 3) (sub zero, 9) gamma(exp p + 2/p + 5) (sub min) K, where gamma(sub min) is the low-energy cutoff to the relativistic electron distribution with a power-law index of p. It can also significantly flatten the radio spectrum. The radio spectrum of the core of 3C 279 is well matched by a model in which stimulated scattering is important, and the additional constraint T(sub B) less than 2 x 10(exp 11)K may be important to the interpretation of the broadband spectra in variable extragalactic compact radio sources. Stimulated scattering reduces the amplitude of the radio frequency variability relative to the X-ray variability, an effect which can be detected by multiwavelength variability studies. Data for a sample of resolved compact radio cores indicate that it is inconsistent to neglect induced Compton scattering when inferring the physical parameters of the sources. The necessary generalizations to the standard synchrotron self-Compton theory are p resented.

  20. Structured Metal Film as Perfect Absorber

    NASA Astrophysics Data System (ADS)

    Xiong, Xiang; Jiang, Shang-Chi; Peng, Ru-Wen; Wang, Mu

    2014-03-01

    With standing U-shaped resonators, fish-spear-like resonator has been designed for the first time as the building block to assemble perfect absorbers. The samples have been fabricated with two-photon polymerization process and FTIR measurement results support the effectiveness of the perfect absorber design. In such a structure the polarization-dependent resonance occurs between the tines of the spears instead of the conventional design where the resonance occurs between the metallic layers separated by a dielectric interlayer. The incident light neither transmits nor reflects back which results in unit absorbance. The power of light is trapped between the tines of spears and finally be absorbed. The whole structure is covered with a continuous metallic layer with good thermo-conductance, which provides an excellent approach to deal with heat dissipation, is enlightening in exploring metamaterial absorbers.

  1. Levelized Cost of Coating (LCOC) for selective absorber materials

    SciTech Connect

    Ho, Clifford K.; Pacheco, James E.

    2014-08-08

    A new metric has been developed to evaluate and compare selective absorber coatings for concentrating solar power applications. Previous metrics have typically considered the performance of the selective coating (i.e., solar absorptance and thermal emittance), but cost and durability were not considered. This report describes the development of the levelized cost of coating (LCOC), which is similar to the levelized cost of energy (LCOE) commonly used to evaluate alternative energy technologies. The LCOC is defined as the ratio of the annualized cost of the coating (and associated costs such as labor and number of heliostats required) to the average annual thermal energy produced by the receiver. The baseline LCOC using Pyromark 2500 paint was found to be %240.055/MWht, and the distribution of LCOC values relative to this baseline were determined in a probabilistic analysis to range from -%241.6/MWht to %247.3/MWht, accounting for the cost of additional (or fewer) heliostats required to yield the same baseline average annual thermal energy produced by the receiver. A stepwise multiple rank regression analysis showed that the initial solar absorptance was the most significant parameter impacting the LCOC, followed by thermal emittance, degradation rate, reapplication interval, and downtime during reapplication.

  2. Absorbed dose to water: Standards and traceability for radiation oncology

    SciTech Connect

    Almond, P.R.

    1995-12-31

    Although the need for appropriate quantities and units for ionizing radiation has existed since shortly after discovery of X-rays, the quantities and units in general use today were not completely formalized until about 15 years ago. The development of appropriate national and international standards have also been ongoing. For many years the quantity, exposure, measured in units of roentgen was the national standard and they were also the quantity and units in which radiotherapy was described. With the introduction of megavoltage X-ray and electron-beam equipment and the adoption of the quantity {open_quotes}absorbed-dose{close_quotes} measured in units of rad (or gray) different approaches to calibrating these beams were needed. This was especially the case since the national standard in terms of exposure at a maximum photon energy for {sup 60}Co gamma rays was only available. Since the late 1960s various machine calibration protocols have been published. These protocols have to accommodate changes in modality, energy, quantities and units between the national standard and the user. Because of this, a new definition of traceability is proposed to accommodate the present system. By recording all intercomparisons and parameters used, an auditable calibration chain can be maintained. Even with the introduction of calibration protocols based upon national absorbed dose standards, the proposed traceability definition will still be needed.

  3. Anomalous Thermal Behavior in Microcalorimeter Gamma-Ray Detectors

    SciTech Connect

    Horansky, Robert D.; Beall, James A.; Irwin, Kent D.; Ullom, Joel N.

    2009-12-16

    Improving the resolution of gamma-ray detectors is important for many fields, including determinations of the Lamb shift in atoms with high atomic numbers, nuclear treaty verification, and environmental monitoring. High-purity germanium detectors are currently the tool of choice for precision gamma-ray spectroscopy. The resolution of these detectors is limited to about 500 eV full-width-at-half-maximum at 100 keV by Fano statistics. In comparison, low-temperature microcalorimeters can provide over an order of magnitude improvement in photon resolution. For instance, a gamma-ray microcalorimeter has achieved 25 eV FWHM resolution at 103 keV. These calorimeters consist of two components, a bulk absorber to stop incident gamma rays and a thermometer made from a thin film electrically biased in the superconducting-to-normal phase transition, called a Transition Edge Sensor, or TES. The standard absorber is bulk, superconducting tin. While tin has historically been the best performing absorber, pulse decays in Sn devices are much slower than predicted. We have begun a systematic study of absorber behavior in order to assess and improve response times. This study leverages two capabilities: the ability to microfabricate highly uniform arrays of gamma-ray detectors and the ability to read out many detectors in a single cool-down using SQUID multiplexer circuits. Here, we present two experiments to identify the source of thermal time constants. The first involves varying properties of the Sn absorber including purity, vendor, and crystal grain size. The second examines the role of the other elements in the microcalorimeter assembly.

  4. Thin film absorber for a solar collector

    DOEpatents

    Wilhelm, William G.

    1985-01-01

    This invention pertains to energy absorbers for solar collectors, and more particularly to high performance thin film absorbers. The solar collectors comprising the absorber of this invention overcome several problems seen in current systems, such as excessive hardware, high cost and unreliability. In the preferred form, the apparatus features a substantially rigid planar frame with a thin film window bonded to one planar side of the frame. An absorber in accordance with the present invention is comprised of two thin film layers that are sealed perimetrically. In a preferred embodiment, thin film layers are formed from a metal/plastic laminate. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. The absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

  5. Identification and elimination of anomalous thermal decay in gamma-ray microcalorimeters

    SciTech Connect

    Horansky, Robert D.; Bennett, Douglas A.; Schmidt, Daniel R.; Ullom, Joel N.; Zink, Barry L.

    2013-11-18

    Microcalorimeter detectors rely on superconducting components and cryogenic temperatures to provide over an order-of-magnitude improvement in energy resolution compared to semiconducting sensors. Resolution improvements impact fields from gamma-ray astrophysics to nuclear safeguards. The temporal response of these detectors has been much slower than predicted from the known device parameters. This discrepancy has been attributed to the dynamics of quasiparticles and phonons in the bulk absorber used for absorbing photons. We will show that long-lived states in the glue used for absorber attachment have been the dominant cause of the slow response. Also, we have fabricated microcalorimeters using metal-to-metal diffusion bonding to attach the absorber. These detectors show a significant improvement in their recovery after gamma-ray events and will now enable study of the internal scattering dynamics of the bulk absorber.

  6. Ultraviolet absorbance screening for DNAPL site compliance

    SciTech Connect

    Misquitta, N.; Foster, D.; Coll, F.; Brourman, M.

    1997-12-31

    The UV Absorbance Effectiveness Demonstration was developed to evaluate the feasibility of using UV absorbance as a surrogate for oil & grease methods of measuring the concentration of coal tar-related constituents in groundwater. Since the current oil & grease method via Freon{reg_sign} extraction is being phased out, a new alternative oil & grease method using a hexane extraction will be introduced in the near future. A secondary objective of this evaluation was to compare the two oil & grease methods, as they relate to facility groundwater, in order to demonstrate the overall robustness of UV absorbance as a surrogate for oil & grease analysis, regardless of the method of extraction.

  7. Bond integrity of microwave absorbers for CEBAF

    SciTech Connect

    A. Ananda; Y. Verma; B.T. Smith; P.H. Johnson; I.E. Campisi; K.E. Finger

    1992-10-01

    The Continuous Electron Beam Accelerator Facility (CEBAF) uses superconducting niobium cavities. Specially developed microwave absorbing ceramics are used in the cavities to absorb the higher order mode power. The ceramic absorbers are brazed to copper mounts. The structural integrity and the thermal contact of the braze joints are essential. The ultrasonic reflection signal from the various bonds is evaluated to locate voids and partial braze surfaces. The acoustic wave properties of the four components of the structure are used as input to an ultrasonic transmission line model which is compared to the experimental data. There is good correlation between the ultrasonic reflection data and destructive testing of the bonds.

  8. Reaction mechanism of Escherichia coli cystathionine gamma-synthase: direct evidence for a pyridoxamine derivative of vinylglyoxylate as a key intermediate in pyridoxal phosphate dependent gamma-elimination and gamma-replacement reactions.

    PubMed

    Brzović, P; Holbrook, E L; Greene, R C; Dunn, M F

    1990-01-16

    Cystathionine gamma-synthase catalyzes a pyridoxal phosphate dependent synthesis of cystathionine from O-succinyl-L-homoserine (OSHS) and L-cysteine via a gamma-replacement reaction. In the absence of L-cysteine, OSHS undergoes an enzyme-catalyzed, gamma-elimination reaction to form succinate, alpha-ketobutyrate, and ammonia. Since elimination of the gamma-substituent is necessary for both reactions, it is reasonable to assume that the replacement and elimination reaction pathways diverge from a common intermediate. Previously, this partitioning intermediate has been assigned to a highly conjugated alpha-iminovinylglycine quininoid (Johnston et al., 1979a). The experiments reported herein support an alternative assignment for the partitioning intermediate. We have examined the gamma-replacement and gamma-elimination reactions of cystathionine gamma-synthase via rapid-scanning stopped-flow and single-wavelength stopped-flow UV-visible spectroscopy. The gamma-elimination reaction is characterized by a rapid decrease in the amplitude of the enzyme internal aldimine spectral band at 422 nm with a concomitant appearance of a new species which absorbs in the 300-nm region. A 485-nm species subsequently accumulates in a much slower relaxation. The gamma-replacement reaction shows a red shift of the 422-nm peak to 425 nm which occurs in the experiment dead time (approximately 3 ms). This relaxation is followed by a decrease in absorbance at 425 nm that is tightly coupled to the appearance of a species which absorbs in the 300-nm region. Reaction of the substrate analogues L-alanine and L-allylglycine with cystathionine gamma-synthase results in bleaching of the 422-nm absorbance and the appearance of a 300-nm species. In the absence of L-cysteine, L-allylglycine undergoes facile proton exchange; in the presence of L-cysteine, L-allylglycine undergoes a gamma-replacement reaction to form a new amino acid, gamma-methylcystathionine. No long-wavelength-absorbing species

  9. gamma-Hexachlorocyclohexane (gamma-HCH)

    Integrated Risk Information System (IRIS)

    gamma - Hexachlorocyclohexane ( gamma - HCH ) ; CASRN 58 - 89 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Asse

  10. Determination of thorium-232 in Canadian soils by gamma-ray spectrometry via lead-212 and actinium-228, interference from uranium

    SciTech Connect

    Zikovsky, L.; Blagoeva, R.

    1994-12-31

    Thorium-232 background levels in non-cultivated Canadian soils (southern and northern Quebec and the Northwest Territories) are presented. Gamma-ray spectrometry was used to determine the activity of {sup 232}Th by measuring the activities of {sup 228}Ac and {sup 212}Pb at 37 sites. The specific activity levels ranged from 2.7 to 95.5 Bq/kg with an overall mean of 24.0 {+-} 15.4 Bq/kg. This activity generated an annual absorbed dose equivalent in air of 0.1 mSv. The activities of {sup 228}Ac and {sup 212}Pb in the soil increased with increasing depth. IT was found that uranium, via its decay product radium, can interfere with the determination of thorium in the soil.

  11. Neutron absorbing coating for nuclear criticality control

    DOEpatents

    Mizia, Ronald E.; Wright, Richard N.; Swank, William D.; Lister, Tedd E.; Pinhero, Patrick J.

    2007-10-23

    A neutron absorbing coating for use on a substrate, and which provides nuclear criticality control is described and which includes a nickel, chromium, molybdenum, and gadolinium alloy having less than about 5% boron, by weight.

  12. Energy absorber uses expanded coiled tube

    NASA Technical Reports Server (NTRS)

    Johnson, E. F.

    1972-01-01

    Mechanical shock mitigating device, based on working material to its failure point, absorbs mechanical energy by bending or twisting tubing. It functions under axial or tangential loading, has no rebound, is area independent, and is easy and inexpensive to build.

  13. Durability of Polymeric Glazing and Absorber Materials

    SciTech Connect

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Milbourne, M.

    2005-01-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. The objective of this task is to quantify lifetimes through measurement of the optical and mechanical stability of candidate polymeric glazing and absorber materials. Polycarbonate sheet glazings, as proposed by two industry partners, have been tested for resistance to UV radiation with three complementary methods. Incorporation of a specific 2-mil thick UV-absorbing screening layer results in glazing lifetimes of at least 15 years; improved screens promise even longer lifetimes. Proposed absorber materials were tested for creep and embrittlement under high temperature, and appear adequate for planned ICS absorbers.

  14. Gamma ray detector shield

    DOEpatents

    Ohlinger, R.D.; Humphrey, H.W.

    1985-08-26

    A gamma ray detector shield comprised of a rigid, lead, cylindrical-shaped vessel having upper and lower portions with an pneumatically driven, sliding top assembly. Disposed inside the lead shield is a gamma ray scintillation crystal detector. Access to the gamma detector is through the sliding top assembly.

  15. Porous absorber for solar air heaters

    SciTech Connect

    Finch, J.A.

    1980-09-10

    A general discussion of the factors affecting solar collector performance is presented. Bench scale tests done to try to determine the heat transfer characteristics of various screen materials are explained. The design, performance, and evaluation of a crude collector with a simple screen stack absorber is treated. The more sophisticated absorber concept, and its first experimental approximation is examined. A short summary of future plans for the collector concept is included. (MHR)

  16. Taming electromagnetic metamaterials for isotropic perfect absorbers

    NASA Astrophysics Data System (ADS)

    Anh, Doan Tung; Viet, Do Thanh; Trang, Pham Thi; Thang, Nguyen Manh; Quy, Ho Quang; Hieu, Nguyen Van; Lam, Vu Dinh; Tung, Nguyen Thanh

    2015-07-01

    Conventional metamaterial absorbers, which consist of a dielectric spacer sandwiched between metamaterial resonators and a metallic ground plane, have been inherently anisotropic. In this paper, we present an alternative approach for isotropic perfect absorbers using symmetric metamaterial structures. We show that by systematically manipulating the electrically and magnetically induced losses, one can achieve a desired absorption without breaking the structural homogeneity. Finite integration simulations and standard retrieval method are performed to elaborate on our idea.

  17. Structured metal film as a perfect absorber.

    PubMed

    Xiong, Xiang; Jiang, Shang-Chi; Hu, Yu-Hui; Peng, Ru-Wen; Wang, Mu

    2013-08-01

    A new type of absorber, a four-tined fish-spear-like resonator (FFR), constructed by the two-photon polymerization process, is reported. An absorbance of more than 90% is experimentally realized and the resonance occurs in the space between the tines. Since a continuous layer of metallic thin film covers the structure, it is perfectly thermo- and electroconductive, which is the mostly desired feature for many applications. PMID:23661582

  18. The response of covered silicon detectors to monoenergetic gamma rays

    NASA Technical Reports Server (NTRS)

    Reier, M.

    1972-01-01

    Measurements were made of the efficiency in detecting gamma rays of a 0.3-mm, a 3-mm, and a 5-mm silicon detector covered with different absorbers. Calibrated sources covering the range from 279 KeV to 2.75 MeV were used. The need for the absorbers in order to obtain meaningful results, and their contribution to detector response at electron biases from 50 to 200 KeV, are discussed in detail. It is shown that the results are independent of the atomic number of the absorber. In addition, the role of the absorber in increasing the efficiency with increasing photon energy for low bias setting is demonstrated for the 0.3-mm crystal. Qualitative explanations are given for the shapes of all curves of efficiency versus energy at each bias.

  19. Perfect terahertz absorber using fishnet based metafilm

    SciTech Connect

    Azad, Abul Kalam; Shchegolkov, Dmitry Yu; Chen, Houtong; Taylor, Antoinette; Smirnova, E I; O' Hara, John F

    2009-01-01

    We present a perfect terahertz (THz) absorber working for a broad-angle of incidence. The two fold symmetry of rectangular fishnet structure allows either complete absorption or mirror like reflection depending on the polarization of incident the THz beam. Metamaterials enable the ability to control the electromagnetic wave in a unique fashion by designing the permittivity or permeability of composite materials with desired values. Although the initial idea of metamaterials was to obtain a negative index medium, however, the evolution of metamaterials (MMs) offers a variety of practically applicable devices for controlling electromagnetic wave such as tunable filters, modulators, phase shifters, compact antenna, absorbers, etc. Terahertz regime, a crucial domain of the electromagnetic wave, is suffering from the scarcity of the efficient devices and might take the advantage of metamaterials. Here, we demonstrate design, fabrication, and characterization of a terahertz absorber based on a simple fishnet metallic film separated from a ground mirror plane by a dielectric spacer. Such absorbers are in particular important for bolometric terahertz detectors, high sensitivity imaging, and terahertz anechoic chambers. Recently, split-ring-resonators (SRR) have been employed for metamaterial-based absorbers at microwave and THz frequencies. The experimental demonstration reveals that such absorbers have absorptivity close to unity at resonance frequencies. However, the downside of these designs is that they all employ resonators of rather complicated shape with many fine parts and so they are not easy to fabricate and are sensitive to distortions.

  20. Radar Absorbing Materials for Cube Stealth Satellite

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Pastore, R.; Vricella, A.; Marchetti, M.

    A Cube Stealth Satellite is proposed for potential applications in defense system. Particularly, the faces of the satellite exposed to the Earth are made of nanostructured materials able to absorb radar surveillance electromagnetic waves, conferring stealth capability to the cube satellite. Microwave absorbing and shielding material tiles are proposed using composite materials consisting in epoxy-resin and carbon nanotubes filler. The electric permittivity of the composite nanostructured materials is measured and discussed. Such data are used by the modeling algorithm to design the microwave absorbing and the shielding faces of the cube satellite. The electromagnetic modeling takes into account for several incidence angles (0-80°), extended frequency band (2-18 GHz), and for the minimization of the electromagnetic reflection coefficient. The evolutionary algorithm used for microwave layered microwave absorber modeling is the recently developed Winning Particle Optimization. The mathematical model of the absorbing structure is finally experimentally validated by comparing the electromagnetic simulation to the measurement of the manufactured radar absorber tile. Nanostructured composite materials manufacturing process and electromagnetic reflection measurements methods are described. Finally, a finite element method analysis of the electromagnetic scattering by cube stealth satellite is performed.

  1. Rehabilitation of gamma

    NASA Astrophysics Data System (ADS)

    Poynton, Charles A.

    1998-07-01

    Gamma characterizes the reproduction of tone scale in an imaging system. Gamma summarizes, in a single numerical parameter, the nonlinear relationship between code value--in an 8-bit system, from 0 through 255--and physical intensity. Nearly all image coding systems are nonlinear, and so involve values of gamma different from unity. Owing to poor understanding of tone scale reproduction, and to misconceptions about nonlinear coding, gamma has acquired a terrible reputation in computer graphics and image processing. In addition, the world-wide web suffers from poor reproduction of grayscale and color images, due to poor handling of nonlinear image coding. This paper aims to make gamma respectable again.

  2. The natural radioactivity measurements in coastal sediment samples along the East Coast of Tamilnadu using gamma spectrometry technique

    SciTech Connect

    Chandramohan, J.; Tholkappian, M.; Harikrishnan, N.; Ravisankar, R.

    2015-08-28

    The natural radioactivity concentration in beach sediment samples collected from Pattipulam to Devanampattinam of East Coast of Tamilnadu have been determined by NaI (TI) gamma ray spectrometer. The specific activity concentrations range from ≤ 2.21 (BDL) to 37.02 Bq kg{sup −1} with a mean of 3.79 Bqkg{sup −1} for {sup 238}U, ≤ 2.11 (BDL) to 643.77 Bqkg{sup −1} with a mean of 49.60 Bqkg{sup −1} for {sup 232}Th and 300.34 Bqkg{sup −1} to 449.08 Bqkg{sup −1} with a mean of 360.23 Bqkg{sup −1} for {sup 40}K. The potential radiological hazards due to natural radionuclides content such as Radium Equivalent activity (Ra{sub eq}), Representative level index (RLI), External hazard index (H{sub ex}), absorbed gamma does rate (D{sub R}), and Annual effective dose rate (AEDR) are estimated to assess the radiation hazard associated with the sediments. The obtained data are compared with the recommended safety limits and international approved values. All the values are well below the recommended safety limits indicating that radiation levels do not poses any significant health hazard to the public in the area as a result of the natural radioactivity of beach sediments. This study may help the baseline data for more extensive works in the same subjects of future studies.

  3. On the definition of absorbed dose

    NASA Astrophysics Data System (ADS)

    Grusell, Erik

    2015-02-01

    Purpose: The quantity absorbed dose is used extensively in all areas concerning the interaction of ionizing radiation with biological organisms, as well as with matter in general. The most recent and authoritative definition of absorbed dose is given by the International Commission on Radiation Units and Measurements (ICRU) in ICRU Report 85. However, that definition is incomplete. The purpose of the present work is to give a rigorous definition of absorbed dose. Methods: Absorbed dose is defined in terms of the random variable specific energy imparted. A random variable is a mathematical function, and it cannot be defined without specifying its domain of definition which is a probability space. This is not done in report 85 by the ICRU, mentioned above. Results: In the present work a definition of a suitable probability space is given, so that a rigorous definition of absorbed dose is possible. This necessarily includes the specification of the experiment which the probability space describes. In this case this is an irradiation, which is specified by the initial particles released and by the material objects which can interact with the radiation. Some consequences are discussed. Specific energy imparted is defined for a volume, and the definition of absorbed dose as a point function involves the specific energy imparted for a small mass contained in a volume surrounding the point. A possible more precise definition of this volume is suggested and discussed. Conclusions: The importance of absorbed dose motivates a proper definition, and one is given in the present work. No rigorous definition has been presented before.

  4. Air kerma based dosimetry calibration for the Leksell Gamma Knife

    SciTech Connect

    Meltsner, Sheridan Griffin; DeWerd, Larry A.

    2009-02-15

    No accepted official protocol exists for the dosimetry of the Leksell Gamma Knife registered (GK) stereotactic radiosurgery device. Establishment of a dosimetry protocol has been complicated by the unique partial-hemisphere arrangement of 201 individual {sup 60}Co beams simultaneously focused on the treatment volume and by the rigid geometry of the GK unit itself. This article proposes an air kerma based dosimetry protocol using either an in-air or in-acrylic phantom measurement to determine the absorbed dose rate of fields of the 18 mm helmet of a GK unit. A small-volume air ionization chamber was used to make measurements at the physical isocenter of three GK units. The absorbed dose rate to water was determined using a modified version of the AAPM Task Group 21 protocol designed for use with {sup 60}Co-based teletherapy machines. This experimentally determined absorbed dose rate was compared to the treatment planning system (TPS) absorbed dose rate. The TPS used with the GK unit is Leksell GammaPlan. The TPS absorbed dose rate at the time of treatment is the absorbed dose rate determined by the physicist at the time of machine commissioning decay corrected to the treatment date. The TPS absorbed dose rate is defined as absorbed dose rate to water at the isocenter of a water phantom with a radius of 8 cm. Measurements were performed on model B and C Gamma Knife units. The absorbed dose rate to water for the 18 mm helmet determined using air-kerma based calculations is consistently between 1.5% and 2.9% higher than the absorbed dose rate provided by the TPS. These air kerma based measurements allow GK dosimetry to be performed with an established dosimetry protocol and without complications arising from the use of and possible variations in solid phantom material. Measurements were also made with the same ionization chamber in a spherical acrylic phantom for comparison. This methodology will allow further development of calibration methods appropriate for the

  5. Method of absorbance correction in a spectroscopic heating value sensor

    SciTech Connect

    Saveliev, Alexei; Jangale, Vilas Vyankatrao; Zelepouga, Sergeui; Pratapas, John

    2013-09-17

    A method and apparatus for absorbance correction in a spectroscopic heating value sensor in which a reference light intensity measurement is made on a non-absorbing reference fluid, a light intensity measurement is made on a sample fluid, and a measured light absorbance of the sample fluid is determined. A corrective light intensity measurement at a non-absorbing wavelength of the sample fluid is made on the sample fluid from which an absorbance correction factor is determined. The absorbance correction factor is then applied to the measured light absorbance of the sample fluid to arrive at a true or accurate absorbance for the sample fluid.

  6. Gamma-Ray Transition-Edge Sensor Microcalorimeters on Solid Substrates

    NASA Astrophysics Data System (ADS)

    Iyomoto, Naoko; Kawakami, Hisao; Maehata, Keisuke; Yoshimine, Ikumi; Shuto, Yuki; Nagayoshi, Kenichiro; Mitsuda, Kazuhisa; Ezaki, Shohei; Takano, Akira; Yoshimoto, Shota; Ishibashi, Kenji

    2016-07-01

    We develop transition-edge-sensor microcalorimeters for gamma-ray spectroscopy. To develop mechanically robust detectors, we fabricated devices with no membrane structure. We report results of three such devices, two with a Bi-absorber and the other with a Sn-absorber. The thickness and volume of each absorber are 1 mm and 0.5-0.6 mm3. We cooled the detectors and irradiated each with gamma rays from a Cs-137 source and observed two types of pulses: slow-rise and fast-rise. The slow-rise pulses are signals from gamma rays absorbed or Compton scattered in the absorbers and the fast-rise pulses are signals resulting from Compton scattering in the Si substrate. We selected the slow pulses to obtain energy spectra. The energy resolutions of the 662-keV photo peak for the Bi-absorber and Sn-absorber devices are, respectively, 4.1 and 7.5 keV, whereas their baseline energy resolutions are 3.2 and 2.6 keV. The degradation in energy resolution is mainly because of the fluctuation of bath temperature. The baseline energy resolutions are more than an order of magnitude worse than the design values. The poor resolution probably arises because of thermal noise from Compton events on the Si substrate.

  7. Porphyrin Based Near Infrared-Absorbing Materials for Organic Photovoltaics

    NASA Astrophysics Data System (ADS)

    Zhong, Qiwen

    photosynthesis. Photosynthesis uses light from the sun to drive a series of chemical reactions. Most natural photosynthetic systems utilize chlorophylls to absorb light energy and carry out photochemical charge separation that stores energy in the form of chemical bonds. The sun produces a broad spectrum of light output that ranges from gamma rays to radio waves. The entire visible range of light (400-700 nm) and some wavelengths in the NIR (700-1000 nm), are highly active in driving photosynthesis. Although the most familiar chlorophyll-containing organisms, such as plants, algae and cyanobacteria, cannot use light longer than 700 nm, anoxygenic bacterium containing bacteriochlorophylls can use the NIR part of the solar spectrum. No organism is known to utilize light of wavelength longer than about 1000 nm for photosynthesis. NIR light has a very low-energy content in each photon, so that large numbers of these low-energy photons would have to be used to drive the chemical reactions of photosynthesis. This is thermodynamically possible but would require a fundamentally different molecular mechanism that is more akin to a heat engine than to photochemistry. Early work on developing light absorbing materials for OPVs was inspired by photosynthesis in which light is absorbed by chlorophyll. Structurally related to chlorophyll is the porphyrin family, which has accordingly drawn much interest as the potential light absorbing component in OPV applications. In this dissertation, the design and detail studies of several porphyrin-based NIR absorbing materials, including pi--extended perylenyl porphryins and pyrazole-containing carbaporphyrins, as well as porphyrin modified single-walled carbon nanotube hybrids, will be presented, dedicating efforts to develop novel and application-oriented materials for efficient utilization of sustainable solar energy.

  8. Resonance production in. gamma gamma. collisions

    SciTech Connect

    Renard, F.M.

    1983-04-01

    The processes ..gamma gamma.. ..-->.. hadrons can be depicted as follows. One photon creates a q anti q pair which starts to evolve; the other photon can either (A) make its own q anti q pair and the (q anti q q anti q) system continue to evolve or (B) interact with the quarks of the first pair and lead to a modified (q anti q) system in interaction with C = +1 quantum numbers. A review of the recent theoretical activity concerning resonance production and related problems is given under the following headings: hadronic C = +1 spectroscopy (q anti q, qq anti q anti q, q anti q g, gg, ggg bound states and mixing effects); exclusive ..gamma gamma.. processes (generalities, unitarized Born method, VDM and QCD); total cross section (soft and hard contributions); q/sup 2/ dependence of soft processes (soft/hard separation, 1/sup +- +/ resonances); and polarization effects. (WHK)

  9. Levelized Cost of Coating (LCOC) for selective absorber materials

    DOE PAGES

    Ho, Clifford K.; Pacheco, James E.

    2014-08-08

    A new metric has been developed to evaluate and compare selective absorber coatings for concentrating solar power applications. Previous metrics have typically considered the performance of the selective coating (i.e., solar absorptance and thermal emittance), but cost and durability were not considered. This report describes the development of the levelized cost of coating (LCOC), which is similar to the levelized cost of energy (LCOE) commonly used to evaluate alternative energy technologies. The LCOC is defined as the ratio of the annualized cost of the coating (and associated costs such as labor and number of heliostats required) to the average annualmore » thermal energy produced by the receiver. The baseline LCOC using Pyromark 2500 paint was found to be %240.055/MWht, and the distribution of LCOC values relative to this baseline were determined in a probabilistic analysis to range from -%241.6/MWht to %247.3/MWht, accounting for the cost of additional (or fewer) heliostats required to yield the same baseline average annual thermal energy produced by the receiver. A stepwise multiple rank regression analysis showed that the initial solar absorptance was the most significant parameter impacting the LCOC, followed by thermal emittance, degradation rate, reapplication interval, and downtime during reapplication.« less

  10. Warm Absorber Diagnostics of AGN Dynamics

    NASA Astrophysics Data System (ADS)

    Kallman, Timothy

    Warm absorbers and related phenomena are observable manifestations of outflows or winds from active galactic nuclei (AGN) that have great potential value. Understanding AGN outflows is important for explaining the mass budgets of the central accreting black hole, and also for understanding feedback and the apparent co-evolution of black holes and their host galaxies. In the X-ray band warm absorbers are observed as photoelectric absorption and resonance line scattering features in the 0.5-10 keV energy band; the UV band also shows resonance line absorption. Warm absorbers are common in low luminosity AGN and they have been extensively studied observationally. They may play an important role in AGN feedback, regulating the net accretion onto the black hole and providing mechanical energy to the surroundings. However, fundamental properties of the warm absorbers are not known: What is the mechanism which drives the outflow?; what is the gas density in the flow and the geometrical distribution of the outflow?; what is the explanation for the apparent relation between warm absorbers and the surprising quasi-relativistic 'ultrafast outflows' (UFOs)? We propose a focused set of model calculations that are aimed at synthesizing observable properties of warm absorber flows and associated quantities. These will be used to explore various scenarios for warm absorber dynamics in order to answer the questions in the previous paragraph. The guiding principle will be to examine as wide a range as possible of warm absorber driving mechanisms, geometry and other properties, but with as careful consideration as possible to physical consistency. We will build on our previous work, which was a systematic campaign for testing important class of scenarios for driving the outflows. We have developed a set of tools that are unique and well suited for dynamical calculations including radiation in this context. We also have state-of-the-art tools for generating synthetic spectra, which are

  11. Ultrathin flexible dual band terahertz absorber

    NASA Astrophysics Data System (ADS)

    Shan, Yan; Chen, Lin; Shi, Cheng; Cheng, Zhaoxiang; Zang, Xiaofei; Xu, Boqing; Zhu, Yiming

    2015-09-01

    We propose an ultrathin and flexible dual band absorber operated at terahertz frequencies based on metamaterial. The metamaterial structure consists of periodical split ring resonators with two asymmetric gaps and a metallic ground plane, separated by a thin-flexible dielectric spacer. Particularly, the dielectric spacer is a free-standing polyimide film with thickness of 25 μm, resulting in highly flexible for our absorber and making it promising for non-planar applications such as micro-bolometers and stealth aircraft. Experimental results show that the absorber has two resonant absorption frequencies (0.41 THz and 0.75 THz) with absorption rates 92.2% and 97.4%, respectively. The resonances at the absorption frequencies come from normal dipole resonance and high-order dipole resonance which is inaccessible in the symmetrical structure. Multiple reflection interference theory is used to analyze the mechanism of the absorber and the results are in good agreement with simulated and experimental results. Furthermore, the absorption properties are studied under various spacer thicknesses. This kind of metamaterial absorber is insensitive to polarization, has high absorption rates (over 90%) with wide incident angles range from 0° to 45° and the absorption rates are also above 90% when wrapping it to a curved surface.

  12. Ultraviolet radiation absorbing compounds in marine organisms

    SciTech Connect

    Chalker, B.E.; Dunlap, W.C. )

    1990-01-09

    Studies on the biological effects of solar ultraviolet radiations are becoming increasingly common, in part due to recent interest in the Antarctic ozone hole and in the perceived potential for global climate change. Marine organisms possess many strategies for ameliorating the potentially damaging effects of UV-B (280-320 nm) and the shorter wavelengths of UV-A (320-400nm). One mechanism is the synthesis of bioaccumulation of ultraviolet radiation absorbing compounds. Several investigators have noted the presence of absorbing compounds in spectrophotometer scans of extracts from a variety of marine organisms, particularly algae and coelenterates containing endosymbiotic algae. The absorbing compounds are often mycosporine-like amino acids. Thirteen mycosporine-like amino acids have already been described, and several others have recently been detected. Although, the mycosporine-like amino acids are widely distributed. these compounds are by no means the only type of UV-B absorbing compounds which has been identified. Coumarins from green algae, quinones from sponges, and indoles from a variety of sources are laternative examples which are documented in the natural products literature. When the biological impact of solar ultraviolet radiation is assessed, adequate attention must be devoted to the process of photoadaptation, including the accumulation of ultraviolet radiation absorbing compounds.

  13. Oxygen absorbers in food preservation: a review.

    PubMed

    Cichello, Simon Angelo

    2015-04-01

    The preservation of packaged food against oxidative degradation is essential to establish and improve food shelf life, customer acceptability, and increase food security. Oxygen absorbers have an important role in the removal of dissolved oxygen, preserving the colour, texture and aroma of different food products, and importantly inhibition of food spoilage microbes. Active packaging technology in food preservation has improved over decades mostly due to the sealing of foods in oxygen impermeable package material and the quality of oxygen absorber. Ferrous iron oxides are the most reliable and commonly used oxygen absorbers within the food industry. Oxygen absorbers have been transformed from sachets of dried iron-powder to simple self-adhesive patches to accommodate any custom size, capacity and application. Oxygen concentration can be effectively lowered to 100 ppm, with applications spanning a wide range of food products and beverages across the world (i.e. bread, meat, fish, fruit, and cheese). Newer molecules that preserve packaged food materials from all forms of degradation are being developed, however oxygen absorbers remain a staple product for the preservation of food and pharmaceutical products to reduce food wastage in developed nations and increased food security in the developing & third world. PMID:25829570

  14. An extremely wideband and lightweight metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Shen, Yang; Pei, Zhibin; Pang, Yongqiang; Wang, Jiafu; Zhang, Anxue; Qu, Shaobo

    2015-06-01

    This paper presents a three-dimensional microwave metamaterial absorber based on the stand-up resistive film patch array. The absorber has wideband absorption, lightweight, and polarization-independent properties. Our design comes from the array of unidirectional stand-up resistive film patches backed by a metallic plane, which can excite multiple standing wave modes. By rolling the resistive film patches as a square enclosure, we obtain the polarization-independent property. Due to the multiple standing wave modes, the most incident energy is dissipated by the resistive film patches, and thus, the ultra-wideband absorption can be achieved by overlapping all the absorption modes at different frequencies. Both the simulated and experimental results show that the absorber possesses a fractional bandwidth of 148.2% with the absorption above 90% in the frequency range from 3.9 to 26.2 GHz. Moreover, the proposed absorber is extremely lightweight. The areal density of the fabricated sample is about 0.062 g/cm2, which is approximately equivalent to that of eight stacked standard A4 office papers. It is expected that our proposed absorber may find potential applications such as electromagnetic interference and stealth technologies.

  15. Ultra-broadband infrared metasurface absorber.

    PubMed

    Guo, Wenliang; Liu, Yuexia; Han, Tiancheng

    2016-09-01

    By using sub-wavelength resonators, metamaterial absorber shows great potential in many scientific and technical applications due to its perfect absorption characteristics. For most practical applications, the absorption bandwidth is one of the most important performance metrics. In this paper, we demonstrate the design of an ultra-broadband infrared absorber based on metasurface. Compared with the prior work [Opt. Express22(S7), A1713-A1724 (2014)], the proposed absorber shows more than twice the absorption bandwidth. The simulated total absorption exceeds 90% from 7.8 to 12.1 um and the full width at half maximum is 50% (from 7.5 to 12.5 μm), which is achieved by using a single layer of metasurface. Further study demonstrates that the absorption bandwidth can be greatly expanded by using two layers of metasurface, i.e. dual-layered absorber. The total absorption of the dual-layered absorber exceeds 80% from 5.2 to 13.7 um and the full width at half maximum is 95% (from 5.1 to 14.1 μm), much greater than those previously reported for infrared spectrum. The absorption decreases with fluctuations as the incident angle increases but remains quasi-constant up to relatively large angles. PMID:27607662

  16. Solar absorber material reflectivity measurements at temperature

    SciTech Connect

    Bonometti, J.A.; Hawk, C.W.

    1999-07-01

    Assessment of absorber shell material properties at high operating temperatures is essential to the full understanding of the solar energy absorption process in a solar thermal rocket. A review of these properties, their application and a new experimental methodology to measure them at high temperatures is presented. The direct application for the research is absorber cavity development for a Solar Thermal Upper Stage (STUS). High temperature measurements, greater than 1,000 Kelvin, are difficult to obtain for incident radiation upon a solid surface that forms an absorber cavity in a solar thermal engine. The basic material properties determine the amount of solar energy that is absorbed, transmitted or reflected and are dependent upon the material's temperature. This investigation developed a new approach to evaluate the material properties (i.e., reflectivity, absorptive) of the absorber wall and experimentally determined them for rhenium and niobium sample coupons. The secular reflectivity was measured both at room temperature and at temperatures near 1,000 Kelvin over a range of angles from 0 to 90 degrees. The same experimental measurements were used to calculate the total reflectivity of the sample by integrating the recorded intensities over a hemisphere. The test methodology used the incident solar energy as the heating source while directly measuring the reflected light (an integrated value over all visible wavelengths). Temperature dependence on total reflectivity was found to follow an inverse power function of the material's temperature.

  17. Oxygen absorbers in food preservation: a review.

    PubMed

    Cichello, Simon Angelo

    2015-04-01

    The preservation of packaged food against oxidative degradation is essential to establish and improve food shelf life, customer acceptability, and increase food security. Oxygen absorbers have an important role in the removal of dissolved oxygen, preserving the colour, texture and aroma of different food products, and importantly inhibition of food spoilage microbes. Active packaging technology in food preservation has improved over decades mostly due to the sealing of foods in oxygen impermeable package material and the quality of oxygen absorber. Ferrous iron oxides are the most reliable and commonly used oxygen absorbers within the food industry. Oxygen absorbers have been transformed from sachets of dried iron-powder to simple self-adhesive patches to accommodate any custom size, capacity and application. Oxygen concentration can be effectively lowered to 100 ppm, with applications spanning a wide range of food products and beverages across the world (i.e. bread, meat, fish, fruit, and cheese). Newer molecules that preserve packaged food materials from all forms of degradation are being developed, however oxygen absorbers remain a staple product for the preservation of food and pharmaceutical products to reduce food wastage in developed nations and increased food security in the developing & third world.

  18. Gamma densitometry for the measurement of skeletal density

    NASA Astrophysics Data System (ADS)

    Chalker, B. E.; Barnes, D. J.

    1990-03-01

    A method is described for the measurement of the density of calcium carbonate materials from the attenuation of a narrow, collimated beam of gamma photons. For the measurement of density for slices, approximately 0.5 to 1.0 cm thick, from the skeletons of reef building corals, the optimum beam energy is 30 34 keV; and measurement is practical from approximately 22 to 100 keV. The potential utilities of five commercially available isotopic sources (109Cd,125I,253Gd,210Pb and241Am) are evaluated. Methods and results are presented for gamma densitometry using210Pb and241Am. The210Pb point source had its principal gamma emission at 46.5 keV. Bremsstrahlung and high energy (800 keV) gamma emissions associated with the210Pb decay grand-daughter were detected, and procedures were developed to accommodate the contribution of these emissions to the overall count rate. The attenuation of count rate by aluminium and aragonite absorbers closely followed simple theoretical considerations provided that narrow energy window settings were used at the radiation monitor. These theoretical considerations take account of the density of the material absorbing the radiation, and hence the density could be determined from the attenuation of the gamma beam. Increased accuracy was achieved by the use of241Am and high speed counting equipment.241Am has its principal gamma emission at 59.6 keV. The attenuation of this gamma beam follows simple theoretical considerations for targets with mass thicknesses from 0 to 6 g cm-2. Aragonite from the shell of a giant clam was found to have slightly different properties in the absorption of gamma photons to aragonite from a coral skeleton. The differences were small but statistically significant.

  19. Circular polarization sensitive absorbers based on graphene

    PubMed Central

    Yang, Kunpeng; Wang, Min; Pu, Mingbo; Wu, Xiaoyu; Gao, Hui; Hu, Chenggang; Luo, Xiangang

    2016-01-01

    It is well known that the polarization of a linearly polarized (LP) light would rotate after passing through a single layer graphene under the bias of a perpendicular magnetostatic field. Here we show that a corresponding phase shift could be expected for circularly polarized (CP) light, which can be engineered to design the circular polarization sensitive devices. We theoretically validate that an ultrathin graphene-based absorber with the thickness about λ/76 can be obtained, which shows efficient absorption >90% within incident angles of ±80°. The angle-independent phase shift produced by the graphene is responsible for the nearly omnidirectional absorber. Furthermore, a broadband absorber in frequencies ranging from 2.343 to 5.885 THz with absorption over 90% is designed by engineering the dispersion of graphene. PMID:27034257

  20. Ferrite HOM Absorber for the RHIC ERL

    SciTech Connect

    Hahn,H.; Choi, E.M.; Hammons, L.

    2008-10-01

    A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurements of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.

  1. Absorber Materials at Room and Cryogenic Temperatures

    SciTech Connect

    F. Marhauser, T.S. Elliott, A.T. Wu, E.P. Chojnacki, E. Savrun

    2011-09-01

    We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

  2. Optical analysis of solar energy tubular absorbers.

    PubMed

    Saltiel, C; Sokolov, M

    1982-11-15

    The energy absorbed by a solar energy tubular receiver element for a single incident ray is derived. Two types of receiver elements were analyzed: (1) an inner tube with an absorbing coating surrounded by a semitransparent cover tube, and (2) a semitransparent inner tube filled with an absorbing fluid surrounded by a semitransparent cover tube. The formation of ray cascades in the semitransparent tubes is considered. A numerical simulation to investigate the influence of the angle of incidence, sizing, thickness, and coefficient of extinction of the tubes was performed. A comparison was made between receiver elements with and without cover tubes. Ray tracing analyses in which rays were followed within the tubular receiver element as well as throughout the rest of the collector were performed for parabolic and circular trough concentrating collectors.

  3. The diffuse gamma-ray flux associated with sub-PEV/PEV neutrinos from starburst galaxies

    SciTech Connect

    Chang, Xiao-Chuan; Wang, Xiang-Yu

    2014-10-01

    One attractive scenario for the excess of sub-PeV/PeV neutrinos recently reported by IceCube is that they are produced by cosmic rays in starburst galaxies colliding with the dense interstellar medium. These proton-proton (pp) collisions also produce high-energy gamma rays, which finally contribute to the diffuse high-energy gamma-ray background. We calculate the diffuse gamma-ray flux with a semi-analytic approach and consider that the very high energy gamma rays will be absorbed in the galaxies and converted into electron-positron pairs, which then lose almost all of their energy through synchrotron radiation in the strong magnetic fields in the starburst region. Since the synchrotron emission goes into energies below GeV, this synchrotron loss reduces the diffuse high-energy gamma-ray flux by a factor of about two, thus leaving more room for other sources to contribute to the gamma-ray background. For an E{sub ν}{sup −2} neutrino spectrum, we find that the diffuse gamma-ray flux contributes about 20% of the observed diffuse gamma-ray background in the 100 GeV range. However, for a steeper neutrino spectrum, this synchrotron loss effect is less important, since the energy fraction in absorbed gamma rays becomes lower.

  4. Absorber topography dependence of phase edge effects

    NASA Astrophysics Data System (ADS)

    Shanker, Aamod; Sczyrba, Martin; Connolly, Brid; Waller, Laura; Neureuther, Andy

    2015-10-01

    Mask topography contributes to phase at the wafer plane, even for OMOG binary masks currently in use at the 22nm node in deep UV (193nm) lithography. Here, numerical experiments with rigorous FDTD simulation are used to study the impact of mask 3D effects on aerial imaging, by varying the height of the absorber stack and its sidewall angle. Using a thin mask boundary layer model to fit to rigorous simulations it is seen that increasing the absorber thickness, and hence the phase through the middle of a feature (bulk phase) monotonically changes the wafer-plane phase. Absorber height also influences best focus, revealed by an up/down shift in the Bossung plot (linewidth vs. defocus). Bossung plot tilt, however, responsible for process window variability at the wafer, is insensitive to changes in the absorber height (and hence also the bulk phase). It is seen to depend instead on EM edge diffraction from the thick mask edge (edge phase), but stays constant for variations in mask thickness within a 10% range. Both bulk phase and edge phase are also independent of sidewall angle fluctuation, which is seen to linearly affect the CD at the wafer, but does not alter wafer phase or the defocus process window. Notably, as mask topography varies, the effect of edge phase can be replicated by a thin mask model with 8nm wide boundary layers, irrespective of absorber height or sidewall angle. The conclusions are validated with measurements on phase shifting masks having different topographic parameters, confirming the strong dependence of phase variations at the wafer on bulk phase of the mask absorber.

  5. Precise dispersion equations of absorbing filter glasses

    NASA Astrophysics Data System (ADS)

    Reichel, S.; Biertümpfel, Ralf

    2014-05-01

    The refractive indices versus wavelength of optical transparent glasses are measured at a few wavelengths only. In order to calculate the refractive index at any wavelength, a so-called Sellmeier series is used as an approximation of the wavelength dependent refractive index. Such a Sellmeier representation assumes an absorbing free (= loss less) material. In optical transparent glasses this assumption is valid since the absorption of such transparent glasses is very low. However, optical filter glasses have often a rather high absorbance in certain regions of the spectrum. The exact description of the wavelength dependent function of the refractive index is essential for an optimized design for sophisticated optical applications. Digital cameras use an IR cut filter to ensure good color rendition and image quality. In order to reduce ghost images by reflections and to be nearly angle independent absorbing filter glass is used, e.g. blue glass BG60 from SCHOTT. Nowadays digital cameras improve their performance and so the IR cut filter needs to be improved and thus the accurate knowledge of the refractive index (dispersion) of the used glasses must be known. But absorbing filter glass is not loss less as needed for a Sellmeier representation. In addition it is very difficult to measure it in the absorption region of the filter glass. We have focused a lot of effort on measuring the refractive index at specific wavelength for absorbing filter glass - even in the absorption region. It will be described how to do such a measurement. In addition we estimate the use of a Sellmeier representation for filter glasses. It turns out that in most cases a Sellmeier representation can be used even for absorbing filter glasses. Finally Sellmeier coefficients for the approximation of the refractive index will be given for different filter glasses.

  6. Engineering reverse saturable absorbers for desired wavelengths

    NASA Astrophysics Data System (ADS)

    Band, Yehuda B.; Scharf, Benjamin

    1986-06-01

    A variety of applications exist for reverse saturable absorbers (RSAs) in laser science (RSAs are substances whose excited-state absorption cross section is larger than their ground-state absorption cross section at a given wavelength and possess a number of other properties). We propose an approach to designing RSAs at a desired wavelength by construction of dimers of dye molecules which absorb near the wavelength of interest. The dimer ground-state absorption is to a state in which the excitation is spread over both monomeric units and the excited-state absorption commences from this state to the doubly excited electronic state in which both monomeric units are excited.

  7. Spin Particle in an Absorbing Environment

    NASA Astrophysics Data System (ADS)

    Amooshahi, M.

    2015-10-01

    The quantum dynamics of a localized spin Particle interacting with an absorbing environment is investigated. The quantum Langevin-Schrödinger equation for spin is obtained. The susceptibility function of the environment is calculated in terms of the coupling function of the spin and the environment. it is shown that the susceptibility function satisfies the Kramers-Kronig relations. Spontaneous emission and the shift frequency of the spin is obtained in terms of the imaginary part of the susceptibility function in frequency domain. Some transition probabilities between the spin states are calculated when the absorbing environment is in the thermal state.

  8. OSCEE fan exhaust bulk absorber treatment evaluation

    NASA Technical Reports Server (NTRS)

    Bloomer, H. E.; Samanich, N. E.

    1980-01-01

    The acoustic suppression capability of bulk absorber material designed for use in the fan exhaust duct walls of the quiet clean short haul experiment engine (OCSEE UTW) was evaluated. The acoustic suppression to the original design for the engine fan duct which consisted of phased single degree-of-freedom wall treatment was tested with a splitter and also with the splitter removed. Peak suppression was about as predicted with the bulk absorber configuration, however, the broadband characteristics were not attained. Post test inspection revealed surface oil contamination on the bulk material which could have caused the loss in bandwidth suppression.

  9. Durability of Polymeric Glazing and Absorber Materials

    SciTech Connect

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Lindquist, C.; Milbourne, M.

    2005-11-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. We have begun evaluation of several new UV-screened polycarbonate sheet glazing constructions. This has involved interactions with several major polymer industry companies to obtain improved candidate samples. Proposed absorber materials were tested for UV resistance, and appear adequate for unglazed ICS absorbers.

  10. Gamma ray transients

    NASA Technical Reports Server (NTRS)

    Cline, Thomas L.

    1987-01-01

    The discovery of cosmic gamma ray bursts was made with systems designed at Los Alamos Laboratory for the detection of nuclear explosions beyond the atmosphere. HELIOS-2 was the first gamma ray burst instrument launched; its initial results in 1976, seemed to deepen the mystery around gamma ray transients. Interplanetary spacecraft data were reviewed in terms of explaining the behavior and source of the transients.

  11. Fluorescence diagnostics for foods subjected to gamma irradiation

    NASA Astrophysics Data System (ADS)

    Kulawansa, Digala M.; Menzel, E. R.; Banford, H. M.

    1996-03-01

    We have examined the inherent fluorescence of pepper and cinnamon samples exposed to radiation from a 60Co gamma source. We find that in the pepper the fluorescence intensity increases with radiation dose and the ratio of fluorescence intensity at two specific wavelengths, 566 and 674 nm, increases with radiation dose. In contrast, in the cinnamon the distinction between unirradiated and irradiated is not clear. Our preliminary work on gamma ray irradiated pepper indicates that laser-induced fluorescence may be utilized to detect the absorbed dose of irradiation of food samples.

  12. {gamma} production at CDF

    SciTech Connect

    Abe, F.

    1995-07-01

    We report on preliminary measurements of the {gamma}(1S), {gamma}(2S) and {gamma}(3S) differential and integrated cross sections in p{bar p} at {radical}s = 1.8 TeV using a sample of 16.6 {+-} 0.6 pb{sup -1} collected by the Collider Detector at Fermilab. The three resonances were reconstructed through the decay {gamma} {yields} {mu}{sup +}{mu}{sup -} in the rapidity region {vert_bar}y{vert_bar} < 0.4. The cross section results are compared to theoretical models of direct bottomonium production.

  13. Gamma Oscillation in Schizophrenia

    PubMed Central

    O'Donnell, Brian F.; Youn, Soyoung; Kwon, Jun Soo

    2011-01-01

    Dysfunctional neural circuitry has been found to be involved in abnormalities of perception and cognition in patients with schizophrenia. Gamma oscillations are essential for integrating information within neural circuits and have therefore been associated with many perceptual and cognitive processes in healthy human subjects and animals. This review presents an overview of the neural basis of gamma oscillations and the abnormalities in the GABAergic interneuronal system thought to be responsible for gamma-range deficits in schizophrenia. We also review studies of gamma activity in sensory and cognitive processes, including auditory steady state response, attention, object representation, and working memory, in animals, healthy humans and patients with schizophrenia. PMID:22216037

  14. Gamma-Ray Bursts

    SciTech Connect

    Paciesas, W.S. ); Fishman, G.J. )

    1992-01-01

    This proceedings represents the works presented at the Gamma-Ray Bursts Workshop -- 1991 which was held on the campus of theUniversity of Alabama in Huntsville, October 16-18. The emphasis ofthe Workshop was to present and discuss new observations of gamma-ray bursts made recently by experiments on the Compton Gamma-RayObservatory (CGRO), Granat, Ginga, Pioneer Venus Orbiter, Prognozand Phobos. These presentations were complemented by some groundbased observations, reanalysis of older data, descriptions offuture gamma-ray burst experiments and a wide-ranging list oftheoretical discussions. Over seventy papers are included in theproceedings. Eleven of them are abstracted for the database. (AIP)

  15. Distributions of 14 elements on 60 selected absorbers from two simulant solutions (acid-dissolved sludge and alkaline supernate) for Hanford HLW Tank 102-SY

    SciTech Connect

    Marsh, S.F.; Svitra, Z.V.; Bowen, S.M.

    1993-10-01

    Sixty commercially available or experimental absorber materials were evaluated for partitioning high-level radioactive waste. These absorbers included cation and anion exchange resins, inorganic exchangers, composite absorbers, and a series of liquid extractants sorbed on porous support-beads. The distributions of 14 elements onto each absorber were measured from simulated solutions that represent acid-dissolved sludge and alkaline supernate solutions from Hanford high-level waste (HLW) Tank 102-SY. The selected elements, which represent fission products (Ce, Cs, Sr, Tc, and Y); actinides (U, Pu, and Am); and matrix elements (Cr, Co, Fe, Mn, Zn, and Zr), were traced by radionuclides and assayed by gamma spectrometry. Distribution coefficients for each of the 1680 element/absorber/solution combinations were measured for dynamic contact periods of 30 min, 2 h, and 6 h to provide sorption kinetics information for the specified elements from these complex media. More than 5000 measured distribution coefficients are tabulated.

  16. The Cooling of a Liquid Absorber using a Small Cooler

    SciTech Connect

    Baynham, D.E.; Bradshaw, T.W.; Green, M.A.; Ishimoto, S.; Liggins, N.

    2005-08-24

    This report discusses the use of small cryogenic coolers for cooling the Muon Ionization Cooling Experiment (MICE) liquid cryogen absorbers. Since the absorber must be able contain liquid helium as well liquid hydrogen, the characteristics of the available 4.2 K coolers are used here. The issues associated with connecting two-stage coolers to liquid absorbers are discussed. The projected heat flows into an absorber and the cool-down of the absorbers using the cooler are presented. The warm-up of the absorber is discussed. Special hydrogen safety issues that may result from the use of a cooler on the absorbers are also discussed.

  17. Integrated tuned vibration absorbers: a theoretical study.

    PubMed

    Gardonio, Paolo; Zilletti, Michele

    2013-11-01

    This article presents a simulation study on two integrated tuned vibration absorbers (TVAs) designed to control the global flexural vibration of lightly damped thin structures subject to broad frequency band disturbances. The first one consists of a single axial switching TVA composed by a seismic mass mounted on variable axial spring and damper elements so that the characteristic damping and natural frequency of the absorber can be switched iteratively to control the resonant response of three flexural modes of the hosting structure. The second one consists of a single three-axes TVA composed by a seismic mass mounted on axial and rotational springs and dampers, which are arranged in such a way that the suspended mass is characterized by uncoupled heave and pitch-rolling vibrations. In this case the three damping and natural frequency parameters of the absorber are tuned separately to control three flexural modes of the hosting structure. The simulation study shows that the proposed single-unit absorbers produce, respectively, 5.3 and 8.7 dB reductions of the global flexural vibration of a rectangular plate between 20 and 120 Hz.

  18. Tunable metamaterial dual-band terahertz absorber

    NASA Astrophysics Data System (ADS)

    Luo, C. Y.; Li, Z. Z.; Guo, Z. H.; Yue, J.; Luo, Q.; Yao, G.; Ji, J.; Rao, Y. K.; Li, R. K.; Li, D.; Wang, H. X.; Yao, J. Q.; Ling, F. R.

    2015-11-01

    We report a design of a temperature controlled tunable dual band terahertz absorber. The compact single unit cell consists of two nested closed square ring resonators and a layer metallic separated by a substrate strontium titanate (STO) dielectric layer. It is found that the absorber has two distinctive absorption peaks at frequencies 0.096 THz and 0.137 THz, whose peaks are attained 97% and 75%. Cooling the absorber from 400 K to 250 K causes about 25% and 27% shift compared to the resonance frequency of room temperature, when we cooling the temperature to 150 K, we could attained both the two tunabilities exceeding 53%. The frequency tunability is owing to the variation of the dielectric constant of the low-temperature co-fired ceramic (LTCC) substrate. The mechanism of the dual band absorber is attributed to the overlapping of dual resonance frequencies, and could be demonstrated by the distributions of the electric field. The method opens up avenues for designing tunable terahertz devices in detection, imaging, and stealth technology.

  19. Composition for absorbing hydrogen from gas mixtures

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Lee, Myung W.

    1999-01-01

    A hydrogen storage composition is provided which defines a physical sol-gel matrix having an average pore size of less than 3.5 angstroms which effectively excludes gaseous metal hydride poisons while permitting hydrogen gas to enter. The composition is useful for separating hydrogen gas from diverse gas streams which may have contaminants that would otherwise render the hydrogen absorbing material inactive.

  20. Moving core beam energy absorber and converter

    DOEpatents

    Degtiarenko, Pavel V.

    2012-12-18

    A method and apparatus for the prevention of overheating of laser or particle beam impact zones through the use of a moving-in-the-coolant-flow arrangement for the energy absorbing core of the device. Moving of the core spreads the energy deposition in it in 1, 2, or 3 dimensions, thus increasing the effective cooling area of the device.

  1. Optimization of ramified absorber networks doing desalination.

    PubMed

    Singleton, Martin S; Heiss, Gregor; Hübler, Alfred

    2011-01-01

    An iterated function system is used to generate fractal-like ramified graph networks of absorbers, which are optimized for desalination performance. The diffusion equation is solved for the boundary case of constant pressure difference at the absorbers and a constant ambient salt concentration far from the absorbers, while constraining both the total length of the network and the total area of the absorbers to be constant as functions of generation G. A linearized form of the solution was put in dimensionless form which depends only on a dimensionless membrane resistance, a dimensionless inverse svelteness ratio, and G. For each of the first nine generations G=2,…,10, the optimal graph shapes were obtained. Total water production rate increases parabolically as a function of generation, with a maximum at G=7. Total water production rate is shown to be approximately linearly related to the power consumed, for a fixed generation. Branching ratios which are optimal for desalination asymptote decreasingly to r=0.510 for large G, while branching angles which are optimal for desalination asymptote decreasingly to 1.17 radians. Asymmetric graphs were found to be less efficient for desalination than symmetric graphs. The geometry which is optimal for desalination does not depend strongly on the dimensionless parameters, but the optimal water production does. The optimal generation was found to increase with the inverse svelteness ratio.

  2. Estimating the radiation absorbed by a human

    NASA Astrophysics Data System (ADS)

    Kenny, Natasha A.; Warland, Jon S.; Brown, Robert D.; Gillespie, Terry G.

    2008-07-01

    The complexities of the interactions between long- and short-wave radiation fluxes and the human body make it inherently difficult to estimate precisely the total radiation absorbed ( R) by a human in an outdoor environment. The purpose of this project was to assess and compare three methods to estimate the radiation absorbed by a human in an outdoor environment, and to compare the impact of applying various skin and clothing albedos ( α h ) on R. Field tests were conducted under both clear and overcast skies to evaluate the performance of applying a cylindrical radiation thermometer (CRT), net radiometer, and a theoretical estimation model to predict R. Three albedos were evaluated: light ( α h = 0.57), medium ( α h = 0.37), and dark ( α h = 0.21). During the sampling periods, the range of error between the methods used to estimate the radiation absorbed by a cylindrical body under clear and overcast skies ranged from 3 to 8%. Clothing and skin albedo had a substantial impact on R, with the mean change in R between the darkest and lightest albedos ranging from 115 to 157 W m - 2 over the sampling period. Radiation is one of the most important variables to consider in outdoor thermal comfort research, as R is often the largest contributor to the human energy balance equation. The methods outlined and assessed in this study can be conveniently applied to provide reliable estimates of the radiation absorbed by a human in an outdoor environment.

  3. Aldehyde-containing urea-absorbing polysaccharides

    NASA Technical Reports Server (NTRS)

    Mueller, W. A.; Hsu, G. C.; Marsh, H. E., Jr. (Inventor)

    1977-01-01

    A novel aldehyde containing polymer (ACP) is prepared by reaction of a polysaccharide with periodate to introduce aldehyde groups onto the C2 - C3 carbon atoms. By introduction of ether and ester groups onto the pendant primary hydroxyl solubility characteristics are modified. The ACP is utilized to absorb nitrogen bases such as urea in vitro or in vivo.

  4. Shock absorber protects motive components against overloads

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Shock absorber with an output shaft, hollow gear, and a pair of springs forming a resilient driving connection between shaft and gear, operates when abnormally high torques are applied. This simple durable frictional device is valuable in rotating mechanisms subject to sudden overloads.

  5. Debuncher Microwave Absorber Tests of January 1992

    SciTech Connect

    Fullett, Ken

    1992-01-01

    This paper describes the tests performed on the microwave absorbers placed in the Debuncher to replace the existing microwave cutoffs. The purpose of the microwave cutoffs is to reduce the transmission of microwave energy through the beam pipe. The old microwave cutoffs consisted of a stainless steel beam pipe of approximately 2.8 inches inside diameter into which a glass tube with an inside diameter of 1.835 inches was placed. The glass tube was coated with a thin coat of microwave absorbing material on its outside. Three of these cutoffs were installed in the Debuncher at locations D6Q5, D1Q7, and D4Q10 (see Figure 1). However, the glass tube was removed from the cutoff at D4Q10 leaving only the metal beam pipe. Please note that there was not an old style microwave cutoff installed at location D2Q09. It was felt that the glass tube cutoff was an aperture restriction in the Debuncher with its small (1.8 inch) inside diameter. It was decided that new cutoffs would be needed that would increase the aperture. The new microwave absorbers consist of a four inch stainless steel beam pipe into which eleven dielectric cores are inserted separated by aluminum spacers. The spacing allows adjustment of the frequency response of the absorber assembly. The inside diameter is 3 inches thus providing an increase of 1.2 inches over the old cutoffs. The new absorbers will be installed at four locations as shown in Figure 1.

  6. Indoor and outdoor in situ high-resolution gamma radiation measurements in urban areas of Cyprus.

    PubMed

    Svoukis, E; Tsertos, H

    2007-01-01

    In situ, high-resolution, gamma-ray spectrometry of a total number of 70 outdoor and 20 indoor representative measurements were performed in preselected, common locations of the main urban areas of Cyprus. Specific activities and gamma absorbed dose rates in air due to the naturally occurring radionuclides of (232)Th and (238)U series, and (40)K are determined and discussed. Effective dose rate to the Cyprus population due to terrestrial gamma radiation is derived directly from this work. The results obtained outdoors match very well with those derived previously by high-resolution gamma spectrometry of soil samples, which were collected from the main island bedrock surface. This implies that the construction and building materials in urban areas do not affect the external gamma dose rate; thus they are mostly of local origin. Finally, the indoor/outdoor gamma dose ratio was found to be 1.4 +/- 0.5. PMID:17065195

  7. High Conduction Neutron Absorber to Simulate Fast Reactor Environment in an Existing Test Reactor

    SciTech Connect

    Guillen, Donna; Greenwood, Lawrence R.; Parry, James

    2014-06-22

    A need was determined for a thermal neutron absorbing material that could be cooled in a gas reactor environment without using large amounts of a coolant that would thermalize the neutron flux. A new neutron absorbing material was developed that provided high conduction so a small amount of water would be sufficient for cooling thereby thermalizing the flux as little as possible. An irradiation experiment was performed to assess the effects of radiation and the performance of a new neutron absorbing material. Neutron fluence monitors were placed inside specially fabricated holders within a set of drop-in capsules and irradiated for up to four cycles in the Advanced Test Reactor. Following irradiation, the neutron fluence monitor wires were analyzed by gamma and x-ray spectrometry to determine the activities of the activation products. The adjusted neutron fluences were calculated and grouped into three bins – thermal, epithermal and fast to evaluate the spectral shift created by the new material. Fluence monitors were evaluated after four different irradiation periods to evaluate the effects of burn-up in the absorbing material. Additionally, activities of the three highest activity isotopes present in the specimens are given.

  8. Neutron absorbers and methods of forming at least a portion of a neutron absorber

    SciTech Connect

    Guillen, Donna P; Porter, Douglas L; Swank, W David; Erickson, Arnold W

    2014-12-02

    Methods of forming at least a portion of a neutron absorber include combining a first material and a second material to form a compound, reducing the compound into a plurality of particles, mixing the plurality of particles with a third material, and pressing the mixture of the plurality of particles and the third material. One or more components of neutron absorbers may be formed by such methods. Neutron absorbers may include a composite material including an intermetallic compound comprising hafnium aluminide and a matrix material comprising pure aluminum.

  9. Directional gamma detector

    DOEpatents

    LeVert, Francis E.; Cox, Samson A.

    1981-01-01

    An improved directional gamma radiation detector has a collector sandwiched etween two layers of insulation of varying thicknesses. The collector and insulation layers are contained within an evacuated casing, or emitter, which releases electrons upon exposure to gamma radiation. Delayed electrons and electrons entering the collector at oblique angles are attenuated as they pass through the insulation layers on route to the collector.

  10. Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Kouveliotou, Chryssa; Wijers, Ralph A. M. J.; Woosley, Stan

    2012-11-01

    Prologue C. Kouveliotou, R. A . M. J. Wijers and S. E. Woosley; 1. The discovery of the gamma-ray burst phenomenon R. W. Klebesadel; 2. Instrumental principles E. E. Fenimore; 3. The BATSE era G. J. Fishman and C. A. Meegan; 4. The cosmological era L. Piro and K. Hurley; 5. The Swift era N. Gehrels and D. N. Burrows; 6. Discoveries enabled by multi-wavelength afterglow observations of gamma-ray bursts J. Greiner; 7. Prompt emission from gamma-ray bursts T. Piran, R. Sari and R. Mochkovitch; 8. Basic gamma-ray burst afterglows P. Mészáros and R. A. M. J. Wijers; 9. The GRB-supernova connection J. Hjorth and J. S. Bloom; 10. Models for gamma-ray burst progenitors and central engines S. E. Woosley; 11. Jets and gamma-ray burst unification schemes J. Granot and E. Ramirez-Ruiz; 12. High-energy cosmic rays and neutrinos E. Waxman; 13. Long gamma-ray burst host galaxies and their environments J. P. U. Fynbo, D. Malesani and P. Jakobsson; 14. Gamma-ray burst cosmology V. Bromm and A. Loeb; 15. Epilogue R. D. Blandford; Index.

  11. Gamma-Ray Pulsars

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2011-01-01

    The Fermi Gamma-Ray Space Telescope has revolutionized the study of pulsar physics with the detection of over 80 gamma-ray pulsars. Several new populations have been discovered, including 24 radio quiet pulsars found through gamma-ray pulsations alone and about 20 millisecond gamma-ray pulsars. The gamma-ray pulsations from millisecond pulsars were discovered by both folding at periods of known radio millisecond pulsars or by detecting them as gamma-ray sources that are followed up by radio pulsar searches. The second method has resulted in a phenomenally successful synergy, with -35 new radio MSPs (to date) having been discovered at Fermi unidentified source locations and the gamma-ray pulsations having then been detected in a number of these using the radio timing solutions. The higher sensitivity and larger energy range of the Fermi Large Area Telescope has produced detailed energy-dependent light curves and phase-resolved spectroscopy on brighter pulsars, that have ruled out polar cap models as the major source of the emission in favor of outer magnetosphere accelerators. The large number of gamma-ray pulsars now allows for the first time meaningful population and sub-population studies that are revealing surprising properties of these fascinating sources.

  12. Muons in gamma showers

    NASA Technical Reports Server (NTRS)

    Stanev, T.; Vankov, C. P.; Halzen, F.

    1985-01-01

    Muon production in gamma-induced air showers, accounting for all major processes. For muon energies in the GeV region the photoproduction is by far the most important process, while the contribution of micron + micron pair creation is not negligible for TeV muons. The total rate of muons in gamma showers is, however, very low.

  13. Gamma-ray astrophysics

    NASA Technical Reports Server (NTRS)

    Stecker, F. W. (Editor); Trombka, J. I. (Editor)

    1973-01-01

    Conference papers on gamma ray astrophysics are summarized. Data cover the energy region from about 0.3 MeV to a few hundred GeV and theoretical models of production mechanisms that give rise to both galactic and extragalactic gamma rays.

  14. Radiometric analysis of construction materials using HPGe gamma-ray spectrometry.

    PubMed

    Khandaker, M U; Jojo, P J; Kassim, H A; Amin, Y M

    2012-11-01

    Concentrations of primordial radionuclides in common construction materials collected from the south-west coastal region of India were determined using a high-purity germanium gamma-ray spectrometer. Average specific activities (Bq kg(-1)) for (238)U((226)Ra) in cement, brick, soil and stone samples were obtained as 54 ± 13, 21 ± 4, 50 ± 12 and 46 ± 8, respectively. Respective values of (232)Th were obtained as 65 ± 10, 21 ± 3, 58 ± 10 and 57 ± 12. Concentrations of (40)K radionuclide in cement, brick, soil and stone samples were found to be 440 ± 91, 290 ± 20, 380 ± 61 and 432 ± 64, respectively. To evaluate the radiological hazards, radium equivalent activity, various hazard indices, absorbed dose rate and annual effective dose have been calculated, and compared with the literature values. Obtained data could be used as reference information to assess any radiological contamination due to construction materials in future. PMID:22887119

  15. Gamma radiation induced effects on slaughterhouse wastewater treatment

    NASA Astrophysics Data System (ADS)

    Melo, Rita; Cabo Verde, Sandra; Branco, Joaquim; Botelho, M. Luisa

    2008-01-01

    A preliminary study using gamma radiation on slaughterhouse wastewater samples was carried out. Chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) results were obtained at a dose rate of 0.9 kGy h -1. A decrease of COD, BOD and colour was observed after irradiation at high absorbed doses. The microbiological results, following irradiation in the same conditions, correlated with the BOD results. The results obtained highlight the potential of this technology for wastewater treatment.

  16. Theoretical investigation of hyperfine field parameters through mossbauer gamma ray

    SciTech Connect

    Ali, Sikander; Hashim, Mohd

    2012-06-05

    When a Mossbauer gamma-ray emitting or absorbing nucleus is placed in a crystalline environment, the quadrupole moment of the nucleus interacts with the electric field gradient set up by the ligands around it. In the transition |7/2>{yields}|5/2> twelve lines are obtained. Applying the multipole radiation field theory and density matrix formalism, the determinant of coherency matrix, intensity and degree of polarization have been calculated for each line.

  17. Optical gamma thermometer

    SciTech Connect

    Koster, Glen Peter; Xia, Hua; Lee, Boon Kwee

    2013-08-06

    An optical gamma thermometer includes a metal mass having a temperature proportional to a gamma flux within a core of a nuclear reactor, and an optical fiber cable for measuring the temperature of the heated metal mass. The temperature of the heated mass may be measured by using one or more fiber grating structures and/or by using scattering techniques, such as Raman, Brillouin, and the like. The optical gamma thermometer may be used in conjunction with a conventional reactor heat balance to calibrate the local power range monitors over their useful in-service life. The optical gamma thermometer occupies much less space within the in-core instrument tube and costs much less than the conventional gamma thermometer.

  18. Effect of gamma and neutron irradiation on the mechanical properties of Spectralon™ porous PTFE

    DOE PAGES

    Gourdin, William H.; Datte, Philip; Jensen, Wayne; Khater, Hesham; Pearson, Mark; Girard, Sylvain; Paillet, Philippe; Alozy, Eric

    2016-07-21

    Here, we establish a correspondence between the mechanical properties (maximum load and failure elongation) of Spectralon™ porous PTFE irradiated with 14 MeV neutrons and 1.17 and 1.33 MeV gammas from a cobalt-60 source. From this correspondence we infer that the effects of neutrons and gammas on this material are approximately equivalent for a given absorbed dose.

  19. COBALT-60 Gamma Irradiation of Shrimp.

    NASA Astrophysics Data System (ADS)

    Sullivan, Nancy L. B.

    Meta- and ortho-tyrosine were measured using high performance liquid chromatography (HPLC) in conjunction with electrochemical detection in shrimp irradiated using cobalt-60 gamma radiation in the absorbed dose range 0.8 to 6.0 kGy, in nonirradiated shrimp, and in bovine serum albumin (BSA) irradiated in dilute aqueous solution at 25.0 kGy. Ortho-tyrosine was measured in nonirradiated BSA. Para-, meta-, and ortho-tyrosine were measured using HPLC in conjunction with uv-absorption detection in dilute aqueous solutions of phenylalanine irradiated in the absorbed dose range 16.0 to 195.0 kGy. The measured yields of tyrosine isomers were approximately linear as a function of absorbed dose in shrimp, and in irradiated solutions of phenylalanine up to 37.0 kGy. The occurrence of meta- and ortho-tyrosine, which had formerly been considered unique radiolytic products, has not previously been reported in nonirradiated shrimp or BSA. The conventional hydrolyzation and analytical techniques used in the present study to measure meta- and ortho-tyrosine may provide the basis for a method to detect and determine the dose used in food irradiation.

  20. Cobalt-60 gamma irradiation of shrimp

    SciTech Connect

    Sullivan, N.L.B.

    1993-01-01

    Meta- and ortho-tyrosine were measured using high performance liquid chromatography (HPLC) in conjunction with electrochemical detection in shrimp irradiated using cobalt-60 gamma radiation in the absorbed dose range 0.8 to 6.0 kGy, in nonirradiated shrimp, and in bovine serum albumin (BSA) irradiated in dilute aqueous solution at 25.0 kGy. Ortho-tyrosine was measured in nonirradiated BSA. Para-, meta-, and ortho-tyrosine was measured using HPLC in conjunction with uv-absorption detection in dilute aqueous solutions of phenylalanine irradiated in the absorbed dose range 16.0 to 195.0 kGy. The measured yields of tyrosine isomers were approximately linear as a function of absorbed dose in shrimp, and in irradiated solutions of phenylalanine up to 37.0 kGy. The occurrence of meta- and ortho-tyrosine, which had formerly been considered unique radiolytic products, has not previously been reported in nonirradiated shrimp or BSA. The conventional hydrolyzation and analytical techniques used in the present study to measure meta- and ortho-tyrosine may provide the basis for a method to detect and determine the dose used in food irradiation.

  1. Absorbed dose thresholds and absorbed dose rate limitations for studies of electron radiation effects on polyetherimides

    NASA Technical Reports Server (NTRS)

    Long, Edward R., Jr.; Long, Sheila Ann T.; Gray, Stephanie L.; Collins, William D.

    1989-01-01

    The threshold values of total absorbed dose for causing changes in tensile properties of a polyetherimide film and the limitations of the absorbed dose rate for accelerated-exposure evaluation of the effects of electron radiation in geosynchronous orbit were studied. Total absorbed doses from 1 kGy to 100 MGy and absorbed dose rates from 0.01 MGy/hr to 100 MGy/hr were investigated, where 1 Gy equals 100 rads. Total doses less than 2.5 MGy did not significantly change the tensile properties of the film whereas doses higher than 2.5 MGy significantly reduced elongation-to-failure. There was no measurable effect of the dose rate on the tensile properties for accelerated electron exposures.

  2. Biodegradable water absorbent synthesized from bacterial poly(amino acid)s.

    PubMed

    Kunioka, Masao

    2004-03-15

    Biodegradable hydrogels prepared by gamma-irradiation from microbial poly(amino acid)s have been studied. pH-Sensitive hydrogels were prepared by the gamma-irradiation of poly(gamma-glutamic acid) (PGA) produced by Bacillus subtilis and poly(epsilon-lysine) (PL) produced by Streptomyces albulus in aqueous solutions. When the gamma-irradiation dose was 19 kGy or more, and the concentration of PGA in water was 2 wt.-% or more, transparent hydrogels could be produced. For the 19 kGy dose, the produced hydrogel was very weak, however, the specific water content (wt. of absorbed water/wt. of dry hydrogel) of this PGA hydrogel was approximately 3,500. The specific water content decreased to 200, increasing when the gamma-irradiation dose was over 100 kGy. Under acid conditions or upon the addition of electrolytes, the PGA hydrogels shrunk. The PGA hydrogel was pH-sensitive and the change in the volume of the hydrogel depended on the pH value outside the hydrogel in the swelling medium. This PGA hydrogel was hydrodegradable and biodegradable. A new novel purifier reagent (coagulant), made from the PGA hydrogels, for contaminated turbid water has been found and developed by Japanese companies. A very small amount of this coagulant (only 2 ppm in turbid water) with poly(aluminum chloride) can be used for the purification of turbid water. A PL aqueous solution also can change into a hydrogel by gamma-irradiation. The specific water content of the PL hydrogel ranged from 20 to 160 depending on the preparation conditions. Under acid conditions, the PL hydrogel swelled because of the ionic repulsion of the protonated amino groups in the PL molecules. The rate of enzymatic degradation of the respective PL hydrogels by a neutral protease was much faster than the rate of simple hydrolytic degradation. PMID:15468223

  3. Laser Electron Gamma Source. Biennial progress report

    SciTech Connect

    Sandorfi, A.M.; Caracappa, A.; Kuczewski, A.; Kistner, O.C.; Lincoln, F.; Miceli, L.; Thorn, C.E.; Hoblit, S.; Khandaker, M. |

    1994-06-01

    The LEGS facility provides intense, polarized, monochromatic {gamma}-ray beams by Compton backscattering laser light from relativistic electrons circulating in the X-Ray storage ring of the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. With the start of ring operations at 2.8 GeV, LEGS {gamma}-ray energies now extend to 370 MeV. Considerable progress has been made in the development of a new laser system that will increase the beam energies to 470 MeV, and this system is expected to come into operation before the next biennial report. The total flux is administratively held at 6 {times} 10{sup 6} s{sup {minus}1}. The {gamma}-ray energy is determined, with a resolution of 5.5 MeV, by detecting the scattering electrons in a magnetic spectrometer. This spectrometer can `tag` all {gamma}-rays with energies from 185 MeV up to the Compton edge. The beam spot size at the target position is 8 mm (V) {times} 18 mm (H), FWHM. For a single laser wavelength, the linear polarization of the beam is 98% at the Compton edge and decreases to 50% at about 1/2 the energy of the edge. By choosing the laser wavelengths appropriately the polarization can be maintained above 85% throughout the tagging range. During the last two years, experimental running at LEGS occupied an average of 3000 hours annually. Highlights of some of the programs are discussed below.

  4. Design of a Multi-Channel Ultra-High Resolution Superconducting Gamma-Ray Spectrometer

    SciTech Connect

    Friedrich, S; Terracol, S F; Miyazaki, T; Drury, O B; Ali, Z A; Cunningham, M F; Niedermayr, T R; Barbee Jr., T W; Batteux, J D; Labov, S E

    2004-11-29

    Superconducting Gamma-ray microcalorimeters operated at temperatures around {approx}0.1 K offer an order of magnitude improvement in energy resolution over conventional high-purity Germanium spectrometers. The calorimeters consist of a {approx}1 mm{sup 3} superconducting or insulating absorber and a sensitive thermistor, which are weakly coupled to a cold bath. Gamma-ray capture increases the absorber temperature in proportion to the Gamma-ray energy, this is measured by the thermistor, and both subsequently cool back down to the base temperature through the weak link. We are developing ultra-high-resolution Gamma-ray spectrometers based on Sn absorbers and superconducting Mo/Cu multilayer thermistors for nuclear non-proliferation applications. They have achieved an energy resolution between 60 and 90 eV for Gamma-rays up to 100 keV. We also build two-stage adiabatic demagnetization refrigerators for user-friendly detector operation at 0.1 K. We present recent results on the performance of single pixel Gamma-ray spectrometers, and discuss the design of a large detector array for increased sensitivity.

  5. A sound absorbing metasurface with coupled resonators

    NASA Astrophysics Data System (ADS)

    Li, Junfei; Wang, Wenqi; Xie, Yangbo; Popa, Bogdan-Ioan; Cummer, Steven A.

    2016-08-01

    An impedance matched surface is able, in principle, to totally absorb the incident sound and yield no reflection, and this is desired in many acoustic applications. Here we demonstrate a design of impedance matched sound absorbing surface with a simple construction. By coupling different resonators and generating a hybrid resonance mode, we designed and fabricated a metasurface that is impedance-matched to airborne sound at tunable frequencies with subwavelength scale unit cells. With careful design of the coupled resonators, over 99% energy absorption at central frequency of 511 Hz with a 50% absorption bandwidth of 140 Hz is achieved experimentally. The proposed design can be easily fabricated, and is mechanically stable. The proposed metasurface can be used in many sound absorption applications such as loudspeaker design and architectural acoustics.

  6. Absorbing Software Testing into the Scrum Method

    NASA Astrophysics Data System (ADS)

    Tuomikoski, Janne; Tervonen, Ilkka

    In this paper we study, how to absorb software testing into the Scrum method. We conducted the research as an action research during the years 2007-2008 with three iterations. The result showed that testing can and even should be absorbed to the Scrum method. The testing team was merged into the Scrum teams. The teams can now deliver better working software in a shorter time, because testing keeps track of the progress of the development. Also the team spirit is higher, because the Scrum team members are committed to the same goal. The biggest change from test manager’s point of view was the organized Product Owner Team. Test manager don’t have testing team anymore, and in the future all the testing tasks have to be assigned through the Product Backlog.

  7. Investigations on Absorber Materials at Cryogenic Temperatures

    SciTech Connect

    Marhauser, Frank; Elliott, Thomas; Rimmer, Robert

    2009-05-01

    In the framework of the 12 GeV upgrade project for the Continuous Electron Beam Accelerator Facility (CEBAF) improvements are being made to refurbish cryomodules housing Thomas Jefferson National Accelerator Facility's (JLab) original 5-cell cavities. Recently we have started to look into a possible simplification of the existing Higher Order Mode (HOM) absorber design combined with the aim to find alternative material candidates. The absorbers are implemented in two HOM-waveguides immersed in the helium bath and operate at 2 K temperature. We have built a cryogenic setup to perform measurements on sample load materials to investigate their lossy characteristics and variations from room temperature down to 2 K. Initial results are presented in this paper.

  8. Infrared bolometers with silicon nitride micromesh absorbers

    NASA Technical Reports Server (NTRS)

    Bock, J. J.; Turner, A. D.; DelCastillo, H. M.; Beeman, J. W.; Lange, A. E.; Mauskopf, P. D.

    1996-01-01

    Sensitive far infrared and millimeter wave bolometers fabricated from a freestanding membrane of low stress silicon nitride are reported. The absorber, consisting of a metallized silicon nitride micromesh thermally isolated by radial legs of silicon nitride, is placed in an integrating cavity to efficiently couple to single mode or multiple mode infrared radiation. This structure provides low heat capacity, low thermal conduction and minimal cross section to energetic particles. A neutron transmutation doped Ge thermister is bump bonded to the center of the device and read out with evaporated Cr-Au leads. The limiting performance of the micromesh absorber is discussed and the recent results obtained from a 300 mK cold stage are summarized.

  9. Mechanically stretchable and tunable metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Zhang, Fuli; Feng, Shuqi; Qiu, Kepeng; Liu, Zijun; Fan, Yuancheng; Zhang, Weihong; Zhao, Qian; Zhou, Ji

    2015-03-01

    In this letter, we present experimental demonstration of a mechanically stretchable and tunable metamaterial absorber composed of dielectric resonator stacked on a thin conductive rubber layer. A near unity absorption is observed due to strong local field confinement around magnetic Mie resonance of dielectric resonator. Furthermore, the interspacing between unit cells is modulated dynamically under uniaxial stress. Owing to the decreases of longitudinal coupling between neighboring unit cells, the resonant absorption peak is reversibly tuned by 410 MHz, as the stain varies up to 180% along H field direction. On the contrary, the resonant absorption state is nearly independent on strain variation when external stress is applied along E field direction, due to the weak transverse interplaying. The mechanically tunable metamaterial absorber featured by flexibility paves a way forwards for actual application.

  10. Imaging highly absorbing nanoparticles using photothermal microscopy

    NASA Astrophysics Data System (ADS)

    Lussier, Simon-Alexandre; Moradi, Hamid; Price, Alain; Murugkar, Sangeeta

    2015-03-01

    Gold nanoparticles (NPs) have tremendous potential in biomedicine. They can be used as absorbing labels inside living cells for the purpose of biomedical imaging, biosensing as well as for photothermal therapy. We demonstrate photothermal imaging of highly-absorbing particles using a pump-probe setup. The photothermal signal is recovered by heterodyne detection, where the excitation pump laser is at 532 nm and the probe laser is at 638 nm. The sample is moved by a scanning stage. Proof of concept images of red polystyrene microspheres and gold nanoparticles are obtained with this home-built multimodal microscope. The increase in temperature at the surface of the gold NPs, due to the pump laser beam, can be directly measured by means of this photothermal microscope and then compared with the results from theoretical predictions. This technique will be useful for characterization of nanoparticles of different shapes, sizes and materials that are used in cancer diagnosis and therapy.

  11. Disposable Diaper Absorbency: Improvements via Advanced Designs.

    PubMed

    Helmes, C Tucker; O'Connor, Robert; Sawyer, Larry; Young, Sharon

    2014-06-24

    Absorbency effectiveness in diapers has improved significantly in recent years with the advent of new ingredient combinations and advanced design features. With these features, many leading products maintain their dryness performance overnight. Considering the importance of holding liquid away from the skin, ongoing research in diaper construction focuses on strategies to increase the effectiveness to capture liquid and help avoid rewetting of infant skin. The layout and design of a disposable diaper allows for distribution of absorbency features where they can provide the optimal benefit. Clinical evidence indicates materials can keep moisture away from the skin in the diapered area, helping maintain proper skin hydration, minimizing irritation, and contributing to reduced rates of diaper rash.

  12. Shock wave absorber having apertured plate

    DOEpatents

    Shin, Y.W.; Wiedermann, A.H.; Ockert, C.E.

    1983-08-26

    The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

  13. Shock wave absorber having apertured plate

    DOEpatents

    Shin, Yong W.; Wiedermann, Arne H.; Ockert, Carl E.

    1985-01-01

    The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

  14. Development and application of rotary shock absorber

    SciTech Connect

    Yamamoto, Kozo; Yamada, Toshihiro; Fukuyama, Katsura

    1995-12-31

    In recent years, rear suspension systems with a single shock absorber unit placed behind the engine, have been used primarily in the middle and large classes of motorcycles. Some features such as the longer rear wheel travel, progressive response characteristics and mass concentration at the center part of motorcycle are effective in improving maneuverability of the motorcycle. In the 1980s, the systems were introduced first in the off-road motorcycles and then in the on-road motorcycles. Performance of the systems are excellent, but there are demands for further improvement of suspension characteristics and space utility at the center part of motorcycle. For this purpose, the authors have developed a prototype of a rotary shock absorber and studied the applicability to modern motorcycles.

  15. Impedance matched thin metamaterials make metals absorbing

    PubMed Central

    Mattiucci, N.; Bloemer, M. J.; Aközbek, N.; D'Aguanno, G.

    2013-01-01

    Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin (<1 micron), polarization independent, extremely efficient absorbers (in principle being capable to reach A > 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others. PMID:24220284

  16. Disposable Diaper Absorbency: Improvements via Advanced Designs.

    PubMed

    Helmes, C Tucker; O'Connor, Robert; Sawyer, Larry; Young, Sharon

    2014-06-24

    Absorbency effectiveness in diapers has improved significantly in recent years with the advent of new ingredient combinations and advanced design features. With these features, many leading products maintain their dryness performance overnight. Considering the importance of holding liquid away from the skin, ongoing research in diaper construction focuses on strategies to increase the effectiveness to capture liquid and help avoid rewetting of infant skin. The layout and design of a disposable diaper allows for distribution of absorbency features where they can provide the optimal benefit. Clinical evidence indicates materials can keep moisture away from the skin in the diapered area, helping maintain proper skin hydration, minimizing irritation, and contributing to reduced rates of diaper rash. PMID:24961785

  17. Impedance matched thin metamaterials make metals absorbing.

    PubMed

    Mattiucci, N; Bloemer, M J; Aközbek, N; D'Aguanno, G

    2013-01-01

    Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin (<1 micron), polarization independent, extremely efficient absorbers (in principle being capable to reach A > 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others. PMID:24220284

  18. Impedance matched thin metamaterials make metals absorbing.

    PubMed

    Mattiucci, N; Bloemer, M J; Aközbek, N; D'Aguanno, G

    2013-11-13

    Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin (<1 micron), polarization independent, extremely efficient absorbers (in principle being capable to reach A > 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others.

  19. Long lived gamma emitting radionuclides in incense.

    PubMed

    Alrefae, Tareq

    2013-10-01

    A study of long-lived gamma emitters in incense was performed. The incense samples originated from seven different countries, and the investigated radionuclides were Ra, Ra, and K. Gamma spectroscopy revealed the presence of all three investigated radionuclides in all samples. Interestingly, the activity concentrations revealed a clear bimodal distribution that distinguished samples that were natural incense from others that were processed incense. The activity concentrations in the latter group were found to be one order of magnitude greater than in the former group. Consequently, the estimated annual effective dose from the latter group was one order of magnitude higher than that of the former group. Nonetheless, the doses from both groups were found to be some three orders of magnitude less than the average worldwide exposure to inhaled natural radionuclides. This finding suggests the radiological safety of incense for the investigated radionuclides.

  20. Tech Transfer Webinar: Energy Absorbing Materials

    SciTech Connect

    Duoss, Eric

    2014-06-17

    A new material has been designed and manufactured at LLNL that can absorb mechanical energy--a cushion--while also providing protection against sheering. This ordered cellular material is 3D printed using direct ink writing techniques under development at LLNL. It is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  1. Design and Manufacture of Energy Absorbing Materials

    ScienceCinema

    Duoss, Eric

    2016-07-12

    Learn about an ordered cellular material that has been designed and manufactured using direct ink writing (DIW), a 3-D printing technology being developed at LLNL. The new material is a patterned cellular material that can absorb mechanical energy-a cushion-while also providing protection against sheering. This material is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  2. Lightweight Energy Absorbers for Blast Containers

    NASA Technical Reports Server (NTRS)

    Balles, Donald L.; Ingram, Thomas M.; Novak, Howard L.; Schricker, Albert F.

    2003-01-01

    Kinetic-energy-absorbing liners made of aluminum foam have been developed to replace solid lead liners in blast containers on the aft skirt of the solid rocket booster of the space shuttle. The blast containers are used to safely trap the debris from small explosions that are initiated at liftoff to sever frangible nuts on hold-down studs that secure the spacecraft to a mobile launch platform until liftoff.

  3. Tech Transfer Webinar: Energy Absorbing Materials

    ScienceCinema

    Duoss, Eric

    2016-07-12

    A new material has been designed and manufactured at LLNL that can absorb mechanical energy--a cushion--while also providing protection against sheering. This ordered cellular material is 3D printed using direct ink writing techniques under development at LLNL. It is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  4. Design and Manufacture of Energy Absorbing Materials

    SciTech Connect

    Duoss, Eric

    2014-05-28

    Learn about an ordered cellular material that has been designed and manufactured using direct ink writing (DIW), a 3-D printing technology being developed at LLNL. The new material is a patterned cellular material that can absorb mechanical energy-a cushion-while also providing protection against sheering. This material is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  5. Load limiting energy absorbing lightweight debris catcher

    NASA Technical Reports Server (NTRS)

    Kahn, Jon B. (Inventor); Schneider, William C. (Inventor)

    1991-01-01

    In the representative embodiment of the invention disclosed, a load limiting, energy absorbing net is arranged to overlay a normally-covered vent opening in the rear bulkhead of the space orbiter vehicle. Spatially-disposed flexible retainer straps are extended from the net and respectively secured to bulkhead brackets spaced around the vent opening. The intermediate portions of the straps are doubled over and stitched together in a pattern enabling the doubled-over portions to progressively separate at a predicable load designed to be well below the tensile capability of the straps as the stitches are successively torn apart by the forces imposed on the retainer members whenever the cover plate is explosively separated from the bulkhead and propelled into the net. By arranging these stitches to be successively torn away at a load below the strap strength in response to forces acting on the retainers that are less than the combined strength of the retainers, this tearing action serves as a predictable compact energy absorber for safely halting the cover plate as the retainers are extended as the net is deployed. The invention further includes a block of an energy-absorbing material positioned in the net for receiving loose debris produced by the explosive release of the cover plate.

  6. Shock wave absorber having a deformable liner

    DOEpatents

    Youngdahl, C.K.; Wiedermann, A.H.; Shin, Y.W.; Kot, C.A.; Ockert, C.E.

    1983-08-26

    This invention discloses a shock wave absorber for a piping system carrying liquid. The absorber has a plastically deformable liner defining the normal flow boundary for an axial segment of the piping system, and a nondeformable housing is spaced outwardly from the liner so as to define a gas-tight space therebetween. The flow capacity of the liner generally corresponds to the flow capacity of the piping system line, but the liner has a noncircular cross section and extends axially of the piping system line a distance between one and twenty times the diameter thereof. Gas pressurizes the gas-tight space equal to the normal liquid pressure in the piping system. The liner has sufficient structural capacity to withstand between one and one-half and two times this normal liquid pressures; but at greater pressures it begins to plastically deform initially with respect to shape to a more circular cross section, and then with respect to material extension by circumferentially stretching the wall of the liner. A high energy shock wave passing through the liner thus plastically deforms the liner radially into the gas space and progressively also as needed in the axial direction of the shock wave to minimize transmission of the shock wave beyond the absorber.

  7. An absorbed dose calorimeter for IMRT dosimetry

    NASA Astrophysics Data System (ADS)

    Duane, S.; Aldehaybes, M.; Bailey, M.; Lee, N. D.; Thomas, C. G.; Palmans, H.

    2012-10-01

    A new calorimeter for dosimetry in small and complex fields has been built. The device is intended for the direct determination of absorbed dose to water in moderately small fields and in composite fields such as IMRT treatments, and as a transfer instrument calibrated against existing absorbed dose standards in conventional reference conditions. The geometry, materials and mode of operation have been chosen to minimize detector perturbations when used in a water phantom, to give a reasonably isotropic response and to minimize the effects of heat transfer when the calorimeter is used in non-reference conditions in a water phantom. The size of the core is meant to meet the needs of measurement in IMRT treatments and is comparable to the size of the air cavity in a type NE2611 ionization chamber. The calorimeter may also be used for small field dosimetry. Initial measurements in reference conditions and in an IMRT head and neck plan, collapsed to gantry angle zero, have been made to estimate the thermal characteristics of the device, and to assess its performance in use. The standard deviation (estimated repeatability) of the reference absorbed dose measurements was 0.02 Gy (0.6%).

  8. Microscopic modeling of nitride intersubband absorbance

    NASA Astrophysics Data System (ADS)

    Montano, Ines; Allerman, A. A.; Wierer, J. J.; Moseley, M.; Skogen, E. J.; Tauke-Pedretti, A.; Vawter, G. A.

    III-nitride intersubband structures have recently attracted much interest because of their potential for a wide variety of applications ranging from electro-optical modulators to terahertz quantum cascade lasers. To overcome present simulation limitations we have developed a microscopic absorbance simulator for nitride intersubband devices. Our simulator calculates the band structure of nitride intersubband systems using a fully coupled 8x8 k.p Hamiltonian and determines the material response of a single period in a density-matrix-formalism by solving the Heisenberg equation including many-body and dephasing contributions. After calculating the polarization due to intersubband transitions in a single period, the resulting absorbance of a superlattice structure including radiative coupling between the different periods is determined using a non-local Green's-function formalism. As a result our simulator allows us to predict intersubband absorbance of superlattice structures with microscopically determined lineshapes and linewidths accounting for both many-body and correlation contributions. This work is funded by Sandia National Laboratories Laboratory Directed Research and Development program. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin.

  9. Wide band cryogenic ultra-high vacuum microwave absorber

    SciTech Connect

    Campisi, Isidoro E.

    1992-01-01

    An absorber wave guide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the wave guide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the wave guide.

  10. Wide band cryogenic ultra-high vacuum microwave absorber

    SciTech Connect

    Campisi, I.E.

    1992-05-12

    An absorber waveguide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the waveguide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the waveguide. 11 figs.

  11. Preparation of perlite-based carbon dioxide absorbent.

    PubMed

    He, H; Wu, L; Zhu, J; Yu, B

    1994-02-01

    A new highly efficient carbon dioxide absorbent consisting of sodium hydroxide, expanded perlite and acid-base indicator was prepared. The absorption efficiency, absorption capacity, flow resistance and color indication for the absorbent were tested and compared with some commercial products. The absorbent can reduce the carbon dioxide content in gases to 3.3 ppb (v/v) and absorbs not less than 35% of its weight of carbon dioxide. Besides its large capacity and sharp color indication, the absorbent has an outstanding advantage of small flow resistance in comparison with other commercial carbon dioxide absorbents. Applications in gas analysis and purification were also investigated.

  12. A comparison of the alpha and gamma radiolysis of CMPO

    SciTech Connect

    Bruce J. Mincher; Stephen P. Mezyk; Gary Groenewold; Gracy Elias

    2011-06-01

    The radiation chemistry of CMPO has been investigated using a combination of irradiation and analytical techniques. The {alpha}-, and {gamma}-irradiation of CMPO resulted in identical degradation rates (G-value, in {mu}mol Gy{sup -1}) for both radiation types, despite the difference in their linear energy transfer (LET). Similarly, variations in {gamma}-ray dose rates did not affect the degradation rate of CMPO. The solvent extraction behavior was different for the two radiation types, however. Gamma-irradiation resulted in steadily increasing distribution ratios for both forward and stripping extractions, with respect to increasing absorbed radiation dose. This was true for samples irradiated as a neat organic solution, or irradiated in contact with the acidic aqueous phase. In contrast, {alpha}-irradiated samples showed a rapid drop in distribution ratios for forward and stripping extractions, followed by essentially constant distribution ratios at higher absorbed doses. These differences in extraction behavior are reconciled by mass spectrometric examination of CMPO decomposition products under the different irradiation sources. Irradiation by {gamma}-rays resulted in the rupture of phosphoryl-methylene bonds with the production of phosphinic acid products. These species are expected to be complexing agents for americium that would result in higher distribution ratios. Irradiation by {alpha}-sources appeared to favor rupture of carbamoyl-methylene bonds with the production of less deleterious acetamide products.

  13. Characterization of gamma radiation inducible thioredoxin h from Spirogyra varians.

    PubMed

    Yoon, Minchul; Yang, Ho-Yeon; Lee, Seung-Sik; Kim, Dong-Ho; Kim, Gwang-Hoon; Choi, Jong-il

    2013-08-15

    In this study, thioredoxin h (Trxh) was isolated and characterized from the fresh water green alga Spirogyra varians, which was one amongst the pool of proteins induced upon gamma radiation treatment. cDNA clones encoding S. varians thioredoxin h were isolated from a pre-constructed S. varians cDNA library. Trxh had a molecular mass of 13.5kDa and contained the canonical WCGPC active site. Recombinant Trxh showed the disulfide reduction activity, and exhibited insulin reduction activity. Also, Trxh had higher 5,5'-dithiobis(2-nitrobenzoic acid) reduction activity with Arabidopsis thioredoxin reductase (TR) than with Escherichia coli TR. Specific expression of the Trxh gene was further analyzed at mRNA and protein levels and was found to increase by gamma irradiation upto the absorbed dose of 3kGy, suggesting that Trxh may have potential functions in protection of biomolecules from gamma irradiation. PMID:23830452

  14. Characterization of gamma radiation inducible thioredoxin h from Spirogyra varians.

    PubMed

    Yoon, Minchul; Yang, Ho-Yeon; Lee, Seung-Sik; Kim, Dong-Ho; Kim, Gwang-Hoon; Choi, Jong-il

    2013-08-15

    In this study, thioredoxin h (Trxh) was isolated and characterized from the fresh water green alga Spirogyra varians, which was one amongst the pool of proteins induced upon gamma radiation treatment. cDNA clones encoding S. varians thioredoxin h were isolated from a pre-constructed S. varians cDNA library. Trxh had a molecular mass of 13.5kDa and contained the canonical WCGPC active site. Recombinant Trxh showed the disulfide reduction activity, and exhibited insulin reduction activity. Also, Trxh had higher 5,5'-dithiobis(2-nitrobenzoic acid) reduction activity with Arabidopsis thioredoxin reductase (TR) than with Escherichia coli TR. Specific expression of the Trxh gene was further analyzed at mRNA and protein levels and was found to increase by gamma irradiation upto the absorbed dose of 3kGy, suggesting that Trxh may have potential functions in protection of biomolecules from gamma irradiation.

  15. Highly ionised absorbers at high redshift

    NASA Astrophysics Data System (ADS)

    Bergeron, Jacqueline; Herbert-Fort, Stéphane

    2005-03-01

    We build a sample of O VI absorption systems in the redshift range 2.0 ≲ z ≲ 2.6 using high spectral resolution data of ten quasars from the VLT-UVES large programme. We investigate the existence of a metal-rich O VI population and define observational criteria for this class of absorbers under the assumption of photoionisation. The low temperatures of nearly half of all O VI absorbers, implied by their line widths, are too low for collisional ionisation to be a dominant process. We estimate the oxygen abundance under the assumption of photoionisation; a striking result is the bimodal distribution of [o/h] with median values close to 0.01 and 0.5 solar for the metal-poor and metal-rich populations, respectively. Using the line widths to fix the temperature or assuming a constant, low gas density does not drastically change the metallicities of the metal-rich population. We present the first estimate of the O VI column density distribution. Assuming a single power-law distribution, f(n) ∝ n-α, yields α ˜ 1.7 and a normalisation of f(n) =2.3× 10-13 at log n(O VI) ˜ 13.5, both with a ˜30% uncertainty. The value of α is similar to that found for C IV surveys, whereas the normalisation factor is about ten times higher. We use f(n) to derive the number density per unit z and cosmic density ωb(O VI), selecting a limited column density range not strongly affected by incompleteness or sample variance. Comparing our results with those obtained at z˜0.1 for a similar range of column densities implies some decline of dn/dz with z. The cosmic O VI density derived from f(n), ωb(O VI)≈ (3.5± 3.20.9) × 10-7, is 2.3 times higher than the value estimated using the observed O VI sample (of which the metal-rich population contributes ˜35%), easing the problem of missing metals at high z (˜ 1/4 of the produced metals) but not solving it. We find that the majori ty of the metal-rich absorbers are located within ˜ 450 km s-1 of strong Ly-α lines and show that

  16. Achieving a multi-band metamaterial perfect absorber via a hexagonal ring dielectric resonator

    NASA Astrophysics Data System (ADS)

    Li, Li-Yang; Wang, Jun; Du, Hong-Liang; Wang, Jia-Fu; Qu, Shao-Bo

    2015-06-01

    A multi-band absorber composed of high-permittivity hexagonal ring dielectric resonators and a metallic ground plate is designed in the microwave band. Near-unity absorptions around 9.785 GHz, 11.525 GHz, and 12.37 GHz are observed for this metamaterial absorber. The dielectric hexagonal ring resonator is made of microwave ceramics with high permittivity and low loss. The mechanism for the near-unity absorption is investigated via the dielectric resonator theory. It is found that the absorption results from electric and magnetic resonances where enhanced electromagnetic fields are excited inside the dielectric resonator. In addition, the resonance modes of the hexagonal resonator are similar to those of standard rectangle resonators and can be used for analyzing hexagonal absorbers. Our work provides a new research method as well as a solid foundation for designing and analyzing dielectric metamaterial absorbers with complex shapes. Project supported by the National Natural Science Foundation of China (Grant Nos. 61331005, 11204378, 11274389, 11304393, and 61302023), the Aviation Science Foundation of China (Grant Nos. 20132796018 and 20123196015), the Natural Science Foundation for Post-Doctoral Scientists of China (Grant Nos. 2013M532131 and 2013M532221), the Natural Science Foundation of Shaanxi Province, China (Grant No. 2013JM6005), and the Special Funds for Authors of Annual Excellent Doctoral Degree Dissertations of China (Grant No. 201242).

  17. Prospects for gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The Solar Maximum Mission and the Gamma Ray Experiment aboard the SMM spacecraft are discussed. Mission plans for interplanetary probes are also discussed. The Gamma Ray observatory and its role in future gamma ray astronomy is highlighted. It is concluded that gamma ray astronomy will be of major importance in the development of astronomical models and in the development of comsological theory.

  18. The gamma-ray observatory

    NASA Technical Reports Server (NTRS)

    1991-01-01

    An overview is given of the Gamma Ray Observatory (GRO) mission. Detection of gamma rays and gamma ray sources, operations using the Space Shuttle, and instruments aboard the GRO, including the Burst and Transient Source Experiment (BATSE), the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), and the Energetic Gamma Ray Experiment Telescope (EGRET) are among the topics surveyed.

  19. Gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1982-01-01

    Cosmic gamma rays, the physical processes responsible for their production and the astrophysical sites from which they were seen are reported. The bulk of the observed gamma ray emission is in the photon energy range from about 0.1 MeV to 1 GeV, where observations are carried out above the atmosphere. There are also, however, gamma ray observations at higher energies obtained by detecting the Cerenkov light produced by the high energy photons in the atmosphere. Gamma ray emission was observed from sources as close as the Sun and the Moon and as distant as the quasar 3C273, as well as from various other galactic and extragalactic sites. The radiation processes also range from the well understood, e.g. energetic particle interactions with matter, to the still incompletely researched, such as radiation transfer in optically thick electron positron plasmas in intense neutron star magnetic fields.

  20. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1991-01-01

    Miscellaneous tasks related to the development of the Bursts and Transient Source Experiment on the Gamma Ray Observatory and to analysis of archival data from balloon flight experiments were performed. The results are summarized and relevant references are included.

  1. Gamma ray line astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.

    1984-01-01

    The interpretations and implications of the astrophysical observations of gamma-ray lines are reviewed. At the Galactic Center e(+)-e(-) pairs from a compact object produce an annihilation line that shows no redshift, indicating an annihilation site far removed from this object. In the jets of SS433, gamma-ray lines are produced by inelastic excitations, probably in dust grains, although line emission from fusion reactions has also been considered. Observations of diffuse galactic line emission reveal recently synthesized radioactive aluminum in the interstellar medium. In gamma-ray bursts, redshifted pair annihilation lines are consistent with a neutron star origin for the bursts. In solar flares, gamma-ray line emission reveals the prompt acceleration of protons and nuclei, in close association with the flare energy release mechanism.

  2. Dynamic gamma knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Luan, Shuang; Swanson, Nathan; Chen, Zhe; Ma, Lijun

    2009-03-01

    Gamma knife has been the treatment of choice for various brain tumors and functional disorders. Current gamma knife radiosurgery is planned in a 'ball-packing' approach and delivered in a 'step-and-shoot' manner, i.e. it aims to 'pack' the different sized spherical high-dose volumes (called 'shots') into a tumor volume. We have developed a dynamic scheme for gamma knife radiosurgery based on the concept of 'dose-painting' to take advantage of the new robotic patient positioning system on the latest Gamma Knife C™ and Perfexion™ units. In our scheme, the spherical high dose volume created by the gamma knife unit will be viewed as a 3D spherical 'paintbrush', and treatment planning reduces to finding the best route of this 'paintbrush' to 'paint' a 3D tumor volume. Under our dose-painting concept, gamma knife radiosurgery becomes dynamic, where the patient moves continuously under the robotic positioning system. We have implemented a fully automatic dynamic gamma knife radiosurgery treatment planning system, where the inverse planning problem is solved as a traveling salesman problem combined with constrained least-square optimizations. We have also carried out experimental studies of dynamic gamma knife radiosurgery and showed the following. (1) Dynamic gamma knife radiosurgery is ideally suited for fully automatic inverse planning, where high quality radiosurgery plans can be obtained in minutes of computation. (2) Dynamic radiosurgery plans are more conformal than step-and-shoot plans and can maintain a steep dose gradient (around 13% per mm) between the target tumor volume and the surrounding critical structures. (3) It is possible to prescribe multiple isodose lines with dynamic gamma knife radiosurgery, so that the treatment can cover the periphery of the target volume while escalating the dose for high tumor burden regions. (4) With dynamic gamma knife radiosurgery, one can obtain a family of plans representing a tradeoff between the delivery time and the

  3. Inorganic UV absorbers for the photostabilisation of wood-clearcoating systems: Comparison with organic UV absorbers

    NASA Astrophysics Data System (ADS)

    Aloui, F.; Ahajji, A.; Irmouli, Y.; George, B.; Charrier, B.; Merlin, A.

    2007-02-01

    Inorganic UV absorbers which are widely used today were originally designed neither as a UV blocker in coatings applications, nor for wood protection. In recent years however, there has been extensive interest in these compounds, especially with regard to their properties as a UV blocker in coating applications. In this work, we carried out a comparative study to look into some inorganic and organic UV absorbers used in wood coating applications. The aim of this study is to determine the photostabilisation performances of each type of UV absorbers, to seek possible synergies and the influences of different wood species. We have also searched to find eventual correlation between these performances and the influence of UV absorbers on the film properties. Our study has compared the performances of the following UV absorbers: hombitec RM 300, hombitec RM 400 from the Sachtleben Company; transparent yellow and red iron oxides from Sayerlack as inorganic UV absorbers; organic UV absorbers Tinuvin 1130 and Tinuvin 5151 from Ciba Company. The study was carried out on three wood species: Abies grandis, tauari and European oak. The environmental constraints (in particular the limitation of the emission of volatile organic compounds VOCs) directed our choice towards aqueous formulations marketed by the Sayerlack Arch Coatings Company. The results obtained after 800 h of dry ageing showed that the Tinuvins and the hombitecs present better wood photostabilisations. On the other hand in wet ageing, with the hombitec, there are appearances of some cracks and an increase in the roughness of the surface. This phenomenon is absent when the Tinuvins are used. With regard to these results, the thermomechanical analyses relating to the follow-up of the change of the glass transition temperature ( Tg) of the various coating systems, show a different behaviour between the two types of absorbers. However, contrary to organic UV absorbers, inorganic ones tend to increase Tg during ageing

  4. Modeling the Effect of Polychromatic Light in Quantitative Absorbance Spectroscopy

    ERIC Educational Resources Information Center

    Smith, Rachel; Cantrell, Kevin

    2007-01-01

    Laboratory experiment is conducted to give the students practical experience with the principles of electronic absorbance spectroscopy. This straightforward approach creates a powerful tool for exploring many of the aspects of quantitative absorbance spectroscopy.

  5. Gamma ray camera

    SciTech Connect

    Robbins, C.D.; Wang, S.

    1980-09-09

    An anger gamma ray camera is improved by the substitution of a gamma ray sensitive, proximity type image intensifier tube for the scintillator screen in the anger camera, the image intensifier tube having a negatively charged flat scintillator screen and a flat photocathode layer and a grounded, flat output phosphor display screen all of the same dimension (Unity image magnification) and all within a grounded metallic tube envelope and having a metallic, inwardly concaved input window between the scintillator screen and the collimator.

  6. β-Cyclodextrin-based oil-absorbent microspheres: preparation and high oil absorbency.

    PubMed

    Song, Ci; Ding, Lei; Yao, Fei; Deng, Jianping; Yang, Wantai

    2013-01-01

    This article reports the preparation and evaluation of polymeric microspheres as a new class of oil-absorbent (POAMs). Based on our earlier oil-absorbents, the present microspheres contained β-cyclodextrin (β-CD) moieties as both cross-linking agent and porogen agent, and showed exciting high oil absorbency, fast oil absorption speed and good reusability. Such microspheres were prepared via suspension polymerization with octadecyl acrylate and butyl acrylate as co-monomers, β-CD derivative as cross-linking agent, 2,2'-azoisobutyronitrile as initiator and polyvinylalcohol as stabilizer. Oil absorbency of the POAMs was, for CCl(4), 83.4; CHCl(3), 75.1; xylene, 48.7; toluene, 42.8; gasoline, 30.0; kerosene 27.1; and diesel, 18.2 g/g (oil/POAMs). Saturation oil absorption reached within 3h in CCl(4). The POAMs exhibited high oil retention percentage (>90%), and can be reused for at least 10 times while keeping oil absorbency almost unchanged. PMID:23044125

  7. Gamma ray optics

    SciTech Connect

    Jentschel, M.; Guenther, M. M.; Habs, D.; Thirolf, P. G.

    2012-07-09

    Via refractive or diffractive scattering one can shape {gamma} ray beams in terms of beam divergence, spot size and monochromaticity. These concepts might be particular important in combination with future highly brilliant gamma ray sources and might push the sensibility of planned experiments by several orders of magnitude. We will demonstrate the experimental feasibility of gamma ray monochromatization on a ppm level and the creation of a gamma ray beam with nanoradian divergence. The results are obtained using the inpile target position of the High Flux Reactor of the ILL Grenoble and the crystal spectrometer GAMS. Since the refractive index is believed to vanish to zero with 1/E{sup 2}, the concept of refractive optics has never been considered for gamma rays. The combination of refractive optics with monochromator crystals is proposed to be a promising design. Using the crystal spectrometer GAMS, we have measured for the first time the refractive index at energies in the energy range of 180 - 2000 keV. The results indicate a deviation from simple 1/E{sup 2} extrapolation of X-ray results towards higher energies. A first interpretation of these new results will be presented. We will discuss the consequences of these results on the construction of refractive optics such as lenses or refracting prisms for gamma rays and their combination with single crystal monochromators.

  8. Method for absorbing an ion from a fluid

    DOEpatents

    Gao, Huizhen; Wang, Yifeng; Bryan, Charles R.

    2007-07-03

    A method for absorbing an ion from a fluid by using dispersing an organic acid into an anion surfactant solution, mixing in a divalent-metal containing compound and a trivalent-metal containing compound and calcining the resulting solid layered double hydroxide product to form an absorbent material and then contacting the absorbent material with an aqueous solution of cations or anions to be absorbed.

  9. Grover walks on a line with absorbing boundaries

    NASA Astrophysics Data System (ADS)

    Wang, Kun; Wu, Nan; Kuklinski, Parker; Xu, Ping; Hu, Haixing; Song, Fangmin

    2016-09-01

    In this paper, we study Grover walks on a line with one and two absorbing boundaries. In particular, we present some results for the absorbing probabilities in both a semi-finite and finite line. Analytical expressions for these absorbing probabilities are presented by using the combinatorial approach. These results are perfectly matched with numerical simulations. We show that the behavior of Grover walks on a line with absorbing boundaries is strikingly different from that of classical walks and that of Hadamard walks.

  10. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  11. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  12. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  13. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  14. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  15. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  16. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  17. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  18. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  19. 21 CFR 868.5310 - Carbon dioxide absorber.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  20. 14 CFR 29.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Tires and shock absorbers. 29.475 Section... shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed to be in their static position and the shock absorbers to be in their most critical position....

  1. 14 CFR 29.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Tires and shock absorbers. 29.475 Section... shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed to be in their static position and the shock absorbers to be in their most critical position....

  2. 21 CFR 878.4755 - Absorbable lung biopsy plug.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Absorbable lung biopsy plug. 878.4755 Section 878...) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4755 Absorbable lung biopsy plug. (a) Identification. A preformed (polymerized) absorbable lung biopsy plug is intended to...

  3. About sound mufflers sound-absorbing panels aircraft engine

    NASA Astrophysics Data System (ADS)

    Dudarev, A. S.; Bulbovich, R. V.; Svirshchev, V. I.

    2016-10-01

    The article provides a formula for calculating the frequency of sound absorbed panel with a perforated wall. And although the sound absorbing structure is a set of resonators Helmholtz, not individual resonators should be considered in acoustic calculations, and all the perforated wall panel. The analysis, showing how the parameters affect the size and sound-absorbing structures in the absorption rate.

  4. A novel broadband waterborne acoustic absorber

    NASA Astrophysics Data System (ADS)

    Wang, Changxian; Wen, Weibin; Huang, Yixing; Chen, Mingji; Lei, Hongshuai; Fang, Daining

    2016-07-01

    In this paper, we extended the ray tracing theory in polar coordinate system, and originally proposed the Snell-Descartes law in polar coordinates. Based on these theories, a novel broadband waterborne acoustic absorber device was proposed. This device is designed with gradient-distributing materials along radius, which makes the incidence acoustic wave ray warps. The echo reduction effects of this device were investigated by finite element analysis, and the numerical results show that the reflectivity of acoustic wave for the new device is lower than that of homogenous and Alberich layers in almost all frequency 0-30 kHz at the same loss factor.

  5. Acoustical model of a Shoddy fibre absorber

    NASA Astrophysics Data System (ADS)

    Manning, John Peter

    Shoddy fibres or "Shoddies" are a mixture of post-consumer and post-industrial fibres diverted from textile waste streams and recycled into their raw fibre form. They have found widespread use as a raw material for manufacturing sound absorbers that include, but are not limited to: automotive, architectural and home appliance applications. The purpose of this project is to develop a simple acoustic model to describe the acoustic behaviour of sound absorbers composed primarily of Shoddy fibres. The model requires knowledge of the material's bulk density only. To date, these materials have not been the focus of much published research and acoustical designers must rely on models that were developed for other materials or are overly complex. For modelling purposes, an equivalent fluid approach is chosen to balance complexity and accuracy. In deriving the proposed model, several popular equivalent fluid models are selected and the required input parameters for each model identified. The models are: the model of Delaney and Bazley, two models by Miki, the model of Johnson in conjunction with the model of Champoux and Allard and the model of Johnson in conjunction with the model of Lafarge. Characterization testing is carried out on sets of Shoddy absorbers produced using three different manufacturing methods. The measured properties are open porosity, tortuosity, airflow resistivity, the viscous and thermal characteristic lengths and the static thermal permeability. Empirical relationships between model parameters and bulk density are then derived and used to populate the selected models. This yields several 'simplified' models with bulk density as the only parameter. The most accurate model is then selected by comparing each model's prediction to the results of normal incidence sound absorption tests. The model of Johnson-Lafarge populated with the empirical relations is the most accurate model over the range of frequencies considered (approx. 300 Hz - 4000 Hz

  6. DHCAL with minimal absorber: measurements with positrons

    NASA Astrophysics Data System (ADS)

    Freund, B.; Neubüser, C.; Repond, J.; Schlereth, J.; Xia, L.; Dotti, A.; Grefe, C.; Ivantchenko, V.; Berenguer Antequera, J.; Calvo Alamillo, E.; Fouz, M.-C.; Marin, J.; Puerta-Pelayo, J.; Verdugo, A.; Brianne, E.; Ebrahimi, A.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Irles, A.; Krivan, F.; Krüger, K.; Kvasnicka, J.; Lu, S.; Lutz, B.; Morgunov, V.; Provenza, A.; Reinecke, M.; Sefkow, F.; Schuwalow, S.; Tran, H. L.; Garutti, E.; Laurien, S.; Matysek, M.; Ramilli, M.; Schroeder, S.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kovalcuk, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; van Doren, B.; Wilson, G. W.; Kawagoe, K.; Hirai, H.; Sudo, Y.; Suehara, T.; Sumida, H.; Takada, S.; Tomita, T.; Yoshioka, T.; Bilokin, S.; Bonis, J.; Cornebise, P.; Pöschl, R.; Richard, F.; Thiebault, A.; Zerwas, D.; Hostachy, J.-Y.; Morin, L.; Besson, D.; Chadeeva, M.; Danilov, M.; Markin, O.; Popova, E.; Gabriel, M.; Goecke, P.; Kiesling, C.; van der Kolk, N.; Simon, F.; Szalay, M.; Corriveau, F.; Blazey, G. C.; Dyshkant, A.; Francis, K.; Zutshi, V.; Kotera, K.; Ono, H.; Takeshita, T.; Ieki, S.; Kamiya, Y.; Ootani, W.; Shibata, N.; Jeans, D.; Komamiya, S.; Nakanishi, H.

    2016-05-01

    In special tests, the active layers of the CALICE Digital Hadron Calorimeter prototype, the DHCAL, were exposed to low energy particle beams, without being interleaved by absorber plates. The thickness of each layer corresponded approximately to 0.29 radiation lengths or 0.034 nuclear interaction lengths, defined mostly by the copper and steel skins of the detector cassettes. This paper reports on measurements performed with this device in the Fermilab test beam with positrons in the energy range of 1 to 10 GeV. The measurements are compared to simulations based on GEANT4 and a standalone program to emulate the detailed response of the active elements.

  7. Gamma-Ray Attenuation Measurements as a Laboratory Experiment: Some Remarks

    ERIC Educational Resources Information Center

    Adamides, E.; Koutroubas, S. K.; Moshonas, N.; Yiasemides, K.

    2011-01-01

    In this article we make some significant remarks on the experimental study of the absorption of gamma radiation passing through matter. These remarks have to do with the seemingly unexpected trend of the measured intensity of radiation versus the thickness of the absorber, which puzzles students and its explanation eludes many laboratory…

  8. A Study on Gamma Irradiation Synthesis of Copper Nanoparticles

    SciTech Connect

    Ahmad, Shahrul Izwan Bin; Ahmad, Md. Soot Bin Hj.; Radiman, Shahidan Bin

    2009-06-01

    A study on the effect of gamma radiation dose and dose rate on the yield of copper nanoparticles produced had been done. Its objective is to show the relationship between the absorbed doses with the yield of production. The copper sulphate solution is prepared with addition of ethanol as radical scavenger. Then the solution is bubbled with nitrogen for before being irradiated at different absorbed dose and dose rate. There are five different dose rates being used in this experiment. Atomic absorption spectroscopy (AAS) was used to detect directly the quantity of copper nanoparticles produced. The AAS results show positive linear relationship between the yields of copper nanoparticles with increasing absorbed dose. Yield of production show independency with dose rate at every absorbed dose. AAS result is supported with UV-Vis analysis data on the supernatant from irradiated products. Transmission electron microscope (TEM) confirms the existence of copper nanoparticles in all samples that being irradiated at absorbed dose of 100 kGy. The size of nanoparticles is range from 2 to 10 nm. Peak from the XRD analysis show the existence of pure copper.

  9. Radiation burst from a single {gamma}-photon field

    SciTech Connect

    Shakhmuratov, R. N.; Vagizov, F.; Kocharovskaya, O.

    2011-10-15

    The radiation burst from a single {gamma}-photon field interacting with a dense resonant absorber is studied theoretically and experimentally. This effect was discovered for the fist time by P. Helisto et al.[Phys. Rev. Lett. 66, 2037 (1991)] and it was named the ''gamma echo''. The echo is generated by a 180 Degree-Sign phase shift of the incident radiation field, attained by an abrupt change of the position of the absorber with respect to the radiation source during the coherence time of the photon wave packet. Three distinguishing cases of the gamma echo are considered; i.e., the photon is in exact resonance with the absorber, close to resonance (on the slope of the absorption line), and far from resonance (on the far wings of the resonance line). In resonance the amplitude of the radiation burst is two times larger than the amplitude of the input radiation field just before its phase shift. This burst was explained by Helisto et al. as a result of constructive interference of the coherently scattered field with the phase-shifted input field, both having almost the same amplitude. We found that out of resonance the scattered radiation field acquires an additional component with almost the same amplitude as the amplitude of the incident radiation field. The phase of the additional field depends on the optical thickness of the absorber and resonant detuning. Far from resonance this field interferes destructively with the phase-shifted incident radiation field and radiation quenching is observed. Close to resonance the three fields interfere constructively and the amplitude of the radiation burst is three times larger than the amplitude of the input radiation field.

  10. Estimation of Organ Absorbed Doses in Patients from 99mTc-diphosphonate Using the Data of MIRDose Software

    PubMed Central

    Shahbazi-Gahrouei, Daryoush; Cheki, Mohsen; Moslehi, Masoud

    2012-01-01

    The purpose of this study was to compare estimation of radiation absorbed doses to patients following bone scans with technetium-99m-labeled methylene diphosphonate (MDP) with the estimates given in MIRDose software. In this study, each patient was injected 25 mCi of 99mTc-MDP. Whole-body images from thirty patients were acquired by gamma camera at 10, 60, 90, 180 minutes after 99mTc-MDP injection. To determine the amount of activity in each organ, conjugate view method was applied on images. MIRD equation was then used to estimate absorbed doses in different organs of patients. At the end, absorbed dose values obtained in this study were compared with the data of MIRDose software. The absorbed doses per unit of injected activity (mGy/MBq × 10–4) for liver, kidneys, bladder wall and spleen were 3.86 ± 1.1, 38.73 ± 4.7, 4.16 ± 1.8 and 3.91 ± 1.3, respectively. The results of this study may be useful to estimate the amount of activity that can be administered to the patient and also showed that methods used in the study for absorbed dose calculation is in good agreement with the data of MIRDose software and it is possible to use by a clinician. PMID:23724374

  11. Configurable metamaterial absorber with pseudo wideband spectrum.

    PubMed

    Zhu, Weiren; Huang, Yongjun; Rukhlenko, Ivan D; Wen, Guangjun; Premaratne, Malin

    2012-03-12

    Metamaterials attain their behavior due to resonant interactions among their subwavelength components and thus show specific designer features only in a very narrow frequency band. There is no simple way to dynamically increase the operating bandwidth of a narrowband metamaterial, but it may be possible to change its central frequency, shifting the spectral response to a new frequency range. In this paper, we propose and experimentally demonstrate a metamaterial absorber that can shift its central operating frequency by using mechanical means. The shift is achieved by varying the gap between the metamaterial and an auxiliary dielectric slab parallel to its surface. We also show that it is possible to create multiple absorption peaks by adjusting the size and/or shape of the dielectric slab, and to shift them by moving the slab relative to the metamaterial. Specifically, using numerical simulations we design a microwave metamaterial absorber and experimentally demonstrate that its central frequency can be set anywhere in a 1.6 GHz frequency range. The proposed configuration is simple and easy to make, and may be readily extended to THz frequencies.

  12. Spacesuit Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Hodgson, Ed; Izenson, Mike; Chan, Weibo; Bue, Grant C.

    2012-01-01

    For decades advanced spacesuit developers have pursued a regenerable, robust nonventing system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA s Spacesuit Water Membrane Evaporator (SWME), and Creare s Lithium Chloride Absorber Radiator (LCAR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. This water vapor is then captured by solid LiCl in the LCAR with a high enthalpy of absorption, resulting in sufficient temperature lift to reject heat to space by radiation. After the sortie, the LCAR would be heated up and dried in a regenerator to drive off and recover the absorbed evaporant. A engineering development prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The LCAR was able to stably reject 75 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

  13. Metamaterial perfect absorber based hot electron photodetection.

    PubMed

    Li, Wei; Valentine, Jason

    2014-06-11

    While the nonradiative decay of surface plasmons was once thought to be only a parasitic process that limits the performance of plasmonic devices, it has recently been shown that it can be harnessed in the form of hot electrons for use in photocatalysis, photovoltaics, and photodetectors. Unfortunately, the quantum efficiency of hot electron devices remains low due to poor electron injection and in some cases low optical absorption. Here, we demonstrate how metamaterial perfect absorbers can be used to achieve near-unity optical absorption using ultrathin plasmonic nanostructures with thicknesses of 15 nm, smaller than the hot electron diffusion length. By integrating the metamaterial with a silicon substrate, we experimentally demonstrate a broadband and omnidirectional hot electron photodetector with a photoresponsivity that is among the highest yet reported. We also show how the spectral bandwidth and polarization-sensitivity can be manipulated through engineering the geometry of the metamaterial unit cell. These perfect absorber photodetectors could open a pathway for enhancing hot electron based photovoltaic, sensing, and photocatalysis systems. PMID:24837991

  14. Fabrication of THz Sensor with Metamaterial Absorber

    NASA Astrophysics Data System (ADS)

    Gonzalez, Hugo; Alves, Fabio; Karunasiri, Gamani

    The terahertz (THz) portion of the electromagnetic spectrum (0.1-10 THz) has not been fully utilized due to the lack of sensitive detectors. Real-time imaging in this spectral range has been demonstrated using uncooled infrared microbolometer cameras and external illumination provided by quantum cascade laser (QCL) based THz sources. However, the microbolometer pixels in the cameras have not been optimized to achieve high sensitivity in THz frequencies. Recently, we have developed a highly sensitive micromechanical THz sensor employing bi-material effect with an integrated metamaterial absorber tuned to the THz frequency of interest. The use of bi-material structures causes deflection on the sensor to as the absorbed THz radiation increases its temperature, which can be monitored optically by reflecting a light beam. This approach eliminates the integration of readout electronics needed in microbolometers. The absorption of THz by metamaterial can be tailored by controlling geometrical parameters. The sensors can be fabricated using conventional microelectronic materials and incorporated into pixels to form focal plane arrays (FPAs). In this presentation, characterization and readout of a THz sensor with integrated metamaterial structure will be described. Supported by DoD.

  15. Erbium concentration dependent absorbance in tellurite glass

    SciTech Connect

    Sazali, E. S. Rohani, M. S. Sahar, M. R. Arifin, R. Ghoshal, S. K. Hamzah, K.

    2014-09-25

    Enhancing the optical absorption cross-section in topically important rare earth doped tellurite glasses is challenging for photonic devices. Controlled synthesis and detailed characterizations of the optical properties of these glasses are important for the optimization. The influence of varying concentration of Er{sup 3+} ions on the absorbance characteristics of lead tellurite glasses synthesized via melt-quenching technique are investigated. The UV-Vis absorption spectra exhibits six prominent peaks centered at 490, 526, 652, 800, 982 and 1520 nm ascribed to the transitions in erbium ion from the ground state to the excited states {sup 4}F{sub 7/2}, {sup 2}H{sub 11/2}, {sup 4}F{sub 9/2}, {sup 4}I{sub 9/2}, {sup 2}H{sub 11/2} and {sup 4}I{sub 13/2}, respectively. The results are analyzed by means of optical band gap E{sub g} and Urbach energy E{sub u}. The values of the energy band gap are found decreased from 2.82 to 2.51 eV and the Urbach energy increased from 0.15 to 0.24 eV with the increase of the Er{sub 2}O{sub 3} concentration from 0 to 1.5 mol%. The excellent absorbance of the prepared tellurite glasses makes them suitable for fabricating solid state lasers.

  16. Method of designing layered sound absorbing materials

    NASA Astrophysics Data System (ADS)

    Atalla, Youssef; Panneton, Raymond

    2002-11-01

    A widely used model for describing sound propagation in porous materials is the Johnson-Champoux-Allard model. This rigid frame model is based on five geometrical properties of the porous medium: resistivity, porosity, tortuosity, and viscous and thermal characteristic lengths. Using this model and with the knowledge of such properties for different absorbing materials, the design of a multiple layered system can be optimized efficiently and rapidly. The overall impedance of the layered systems can be calculated by the repeated application of single layer impedance equation. The knowledge of the properties of the materials involved in the layered system and their physical meaning, allows to perform by computer a systematic evaluation of potential layer combinations rather than do it experimentally which is time consuming and always not efficient. The final design of layered materials can then be confirmed by suitable measurements. A method of designing the overall acoustic absorption of multiple layered porous materials is presented. Some aspects based on the material properties, for designing a flat layered absorbing system are considered. Good agreement between measured and computed sound absorption coefficients has been obtained for the studied configurations. [Work supported by N.S.E.R.C. Canada, F.C.A.R. Quebec, and Bombardier Aerospace.

  17. Nano {gamma}'/{gamma}'' composite precipitates in Alloy 718

    SciTech Connect

    Phillips, P. J.; McAllister, D.; Gao, Y.; Lv, D.; Williams, R. E. A.; Wang, Y.; Mills, M. J.; Peterson, B.

    2012-05-21

    Nanoscale composite precipitates of Alloy 718 have been investigated with both high-resolution scanning transmission electron microscopy and phase field modeling. Chemical analysis via energy-dispersive x-ray spectroscopy allowed for the differentiation of {gamma}' and {gamma}'' particles, which is not otherwise possible through traditional Z-contrast methods. Phase field modeling was applied to determine the stress distribution and elastic interaction around and between the particles, respectively, and it was determined that a composite particle (of both {gamma}' and {gamma}'') has an elastic energy that is significantly lower than, for example, single {gamma}' and {gamma}'' precipitates which are non-interacting.

  18. A novel structure for tunable terahertz absorber based on graphene.

    PubMed

    Xu, Bing-Zheng; Gu, Chang-Qing; Li, Zhuo; Niu, Zhen-Yi

    2013-10-01

    Graphene can be used as a platform for tunable absorbers for its tunability of conductivity. In this paper, we proposed an "uneven dielectric slab structure" for the terahertz (THz) tunable absorber based on graphene. The absorber consists of graphene-dielectric stacks and an electric conductor layer, which is easy to fabricate in the manufacturing technique. Fine tuning of the absorption resonances can be conveniently achieved by adjusting the bias voltage. Both narrowband and broadband tunable absorbers made of this structure are demonstrated without using a patterned graphene. In addition, this type of graphene-based absorber exhibits stable resonances with a wide range angles of obliquely incident electromagnetic waves. PMID:24104291

  19. Comparison of LSO and BGO block detectors for prompt gamma imaging in ion beam therapy

    NASA Astrophysics Data System (ADS)

    Hueso-González, F.; Biegun, A. K.; Dendooven, P.; Enghardt, W.; Fiedler, F.; Golnik, C.; Heidel, K.; Kormoll, T.; Petzoldt, J.; Römer, K. E.; Schwengner, R.; Wagner, A.; Pausch, G.

    2015-09-01

    A major weakness of ion beam therapy is the lack of tools for verifying the particle range in clinical routine. The application of the Compton camera concept for the imaging of prompt gamma rays, a by-product of the irradiation correlated to the dose distribution, is a promising approach for range assessment and even three-dimensional in vivo dosimetry. Multiple position sensitive gamma ray detectors arranged in scatter and absorber planes, together with an imaging algorithm, are required to reconstruct the prompt gamma emission density map. Conventional block detectors deployed in Positron Emission Tomography (PET), which are based on Lu2SiO5:Ce (LSO) and Bi4Ge3O12 (BGO) scintillators, are suitable candidates for the absorber of a Compton camera due to their high density and absorption efficiency with respect to the prompt gamma energy range (several MeV). We compare experimentally LSO and BGO block detectors in clinical-like radiation fields in terms of energy, spatial and time resolution. The high energy range compensates for the low light yield of the BGO material and boosts significantly its performance compared to the PET scenario. Notwithstanding the overall superiority of LSO, BGO catches up in the field of prompt gamma imaging and can be considered as a competitive alternative to LSO for the absorber plane due to its lower price and the lack of intrinsic radioactivity.

  20. Gamma ray camera

    DOEpatents

    Perez-Mendez, V.

    1997-01-21

    A gamma ray camera is disclosed for detecting rays emanating from a radiation source such as an isotope. The gamma ray camera includes a sensor array formed of a visible light crystal for converting incident gamma rays to a plurality of corresponding visible light photons, and a photosensor array responsive to the visible light photons in order to form an electronic image of the radiation therefrom. The photosensor array is adapted to record an integrated amount of charge proportional to the incident gamma rays closest to it, and includes a transparent metallic layer, photodiode consisting of a p-i-n structure formed on one side of the transparent metallic layer, and comprising an upper p-type layer, an intermediate layer and a lower n-type layer. In the preferred mode, the scintillator crystal is composed essentially of a cesium iodide (CsI) crystal preferably doped with a predetermined amount impurity, and the p-type upper intermediate layers and said n-type layer are essentially composed of hydrogenated amorphous silicon (a-Si:H). The gamma ray camera further includes a collimator interposed between the radiation source and the sensor array, and a readout circuit formed on one side of the photosensor array. 6 figs.

  1. Gamma ray camera

    DOEpatents

    Perez-Mendez, Victor

    1997-01-01

    A gamma ray camera for detecting rays emanating from a radiation source such as an isotope. The gamma ray camera includes a sensor array formed of a visible light crystal for converting incident gamma rays to a plurality of corresponding visible light photons, and a photosensor array responsive to the visible light photons in order to form an electronic image of the radiation therefrom. The photosensor array is adapted to record an integrated amount of charge proportional to the incident gamma rays closest to it, and includes a transparent metallic layer, photodiode consisting of a p-i-n structure formed on one side of the transparent metallic layer, and comprising an upper p-type layer, an intermediate layer and a lower n-type layer. In the preferred mode, the scintillator crystal is composed essentially of a cesium iodide (CsI) crystal preferably doped with a predetermined amount impurity, and the p-type upper intermediate layers and said n-type layer are essentially composed of hydrogenated amorphous silicon (a-Si:H). The gamma ray camera further includes a collimator interposed between the radiation source and the sensor array, and a readout circuit formed on one side of the photosensor array.

  2. Gamma Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    2000-01-01

    The project has progressed successfully during this period of performance. The highlights of the Gamma Ray Astronomy teams efforts are: (1) Support daily BATSE data operations, including receipt, archival and dissemination of data, quick-look science analysis, rapid gamma-ray burst and transient monitoring and response efforts, instrument state-of-health monitoring, and instrument commanding and configuration; (2) On-going scientific analysis, including production and maintenance of gamma-ray burst, pulsed source and occultation source catalogs, gamma-ray burst spectroscopy, studies of the properties of pulsars and black holes, and long-term monitoring of hard x-ray sources; (3) Maintenance and continuous improvement of BATSE instrument response and calibration data bases; (4) Investigation of the use of solid state detectors for eventual application and instrument to perform all sky monitoring of X-Ray and Gamma sources with high sensitivity; and (5) Support of BATSE outreach activities, including seminars, colloquia and World Wide Web pages. The highlights of this efforts can be summarized in the publications and presentation list.

  3. Container and method for absorbing and reducing hydrogen concentration

    DOEpatents

    Wicks, George G.; Lee, Myung W.; Heung, Leung K.

    2001-01-01

    A method for absorbing hydrogen from an enclosed environment comprising providing a vessel; providing a hydrogen storage composition in communication with a vessel, the hydrogen storage composition further comprising a matrix defining a pore size which permits the passage of hydrogen gas while blocking the passage of gaseous poisons; placing a material within the vessel, the material evolving hydrogen gas; sealing the vessel; and absorbing the hydrogen gas released into the vessel by the hydrogen storage composition. A container for absorbing evolved hydrogen gas comprising: a vessel having an interior and adapted for receiving materials which release hydrogen gas; a hydrogen absorbing composition in communication with the interior, the composition defining a matrix surrounding a hydrogen absorber, the matrix permitting the passage of hydrogen gas while excluding gaseous poisons; wherein, when the vessel is sealed, hydrogen gas, which is released into the vessel interior, is absorbed by the hydrogen absorbing composition.

  4. Composite neutron absorbing coatings for nuclear criticality control

    DOEpatents

    Wright, Richard N.; Swank, W. David; Mizia, Ronald E.

    2005-07-19

    Thermal neutron absorbing composite coating materials and methods of applying such coating materials to spent nuclear fuel storage systems are provided. A composite neutron absorbing coating applied to a substrate surface includes a neutron absorbing layer overlying at least a portion of the substrate surface, and a corrosion resistant top coat layer overlying at least a portion of the neutron absorbing layer. An optional bond coat layer can be formed on the substrate surface prior to forming the neutron absorbing layer. The neutron absorbing layer can include a neutron absorbing material, such as gadolinium oxide or gadolinium phosphate, dispersed in a metal alloy matrix. The coating layers may be formed by a plasma spray process or a high velocity oxygen fuel process.

  5. Determination of decay coefficients for combustors with acoustic absorbers

    NASA Technical Reports Server (NTRS)

    Mitchell, C. E.; Espander, W. R.; Baer, M. R.

    1972-01-01

    An analytical technique for the calculation of linear decay coefficients in combustors with acoustic absorbers is presented. Tuned circumferential slot acoustic absorbers were designed for the first three transverse modes of oscillation, and decay coefficients for these absorbers were found as a function of backing distance for seven different chamber configurations. The effectiveness of the absorbers for off-design values of the combustion response and acoustic mode is also investigated. Results indicate that for tuned absorbers the decay coefficient increases approximately as the cube of the backing distance. For most off-design situations the absorber still provides a damping effect. However, if an absorber designed for some higher mode of oscillation is used to damp lower mode oscillations, a driving effect is frequently found.

  6. Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors: Preprint

    SciTech Connect

    Stynes, J. K.; Ihas, B.

    2012-04-01

    As we pursue efforts to lower the capital and installation costs of parabolic trough solar collectors, it is essential to maintain high optical performance. While there are many optical tools available to measure the reflector slope errors of parabolic trough solar collectors, there are few tools to measure the absorber alignment. A new method is presented here to measure the absorber alignment in two dimensions to within 0.5 cm. The absorber alignment is measured using a digital camera and four photogrammetric targets. Physical contact with the receiver absorber or glass is not necessary. The alignment of the absorber is measured along its full length so that sagging of the absorber can be quantified with this technique. The resulting absorber alignment measurement provides critical information required to accurately determine the intercept factor of a collector.

  7. Gamma radiation effects on silicon photonic waveguides.

    PubMed

    Grillanda, Stefano; Singh, Vivek; Raghunathan, Vivek; Morichetti, Francesco; Melloni, Andrea; Kimerling, Lionel; Agarwal, Anuradha M

    2016-07-01

    To support the use of integrated photonics in harsh environments, such as outer space, the hardness threshold to high-energy radiation must be established. Here, we investigate the effects of gamma (γ) rays, with energy in the MeV-range, on silicon photonic waveguides. By irradiation of high-quality factor amorphous silicon core resonators, we measure the impact of γ rays on the materials incorporated in our waveguide system, namely amorphous silicon, silicon dioxide, and polymer. While we show the robustness of amorphous silicon and silicon dioxide up to an absorbed dose of 15 Mrad, more than 100× higher than previous reports on crystalline silicon, polymer materials exhibit changes with doses as low as 1 Mrad. PMID:27367099

  8. Coenzyme Q10-Binding/Transfer Protein Saposin B also Binds gamma-Tocopherol.

    PubMed

    Jin, Guangzhi; Horinouchi, Ryo; Sagawa, Tomofumi; Orimo, Nobutsune; Kubo, Hiroshi; Yoshimura, Shinichi; Fujisawa, Akio; Kashiba, Misato; Yamamoto, Yorihiro

    2008-09-01

    gamma-Tocopherol, the major form of dietary vitamin E, is absorbed in the intestine and is secreted in chylomicrons, which are then transferred to liver lysosomes. Most gamma-tocopherol is transferred to liver microsomes and is catabolized by cytochrome p450. Due to the hydrophobicity of gamma-tocopherol, a binding and transfer protein is plausible, but none have yet been isolated and characterized. We recently found that a ubiquitous cytosolic protein, saposin B, binds and transfers coenzyme Q10 (CoQ10), which is an essential factor for ATP production and an important antioxidant. Here, we report that saposin B also binds gamma-tocopherol, but not alpha-tocopherol, as efficiently as CoQ10 at pH 7.4. At acidic pH, saposin B binds gamma-tocopherol preferentially to CoQ10 and alpha-tocopherol. Furthermore, we confirmed that saposin B selectively binds gamma-tocopherol instead of CoQ10 and alpha-tocopherol at every pH between 5.4 and 8.0 when all three lipids are competing for binding. We detected gamma-tocopherol in human saposin B monoclonal antibody-induced immunoprecipitates from human urine, although the amount of gamma-tocopherol was much smaller than that of CoQ10. These results suggest that saposin B binds and transports gamma-tocopherol in human cells.

  9. Method of absorbing UF.sub.6 from gaseous mixtures in alkamine absorbents

    DOEpatents

    Lafferty, Robert H.; Smiley, Seymour H.; Radimer, Kenneth J.

    1976-04-06

    A method of recovering uranium hexafluoride from gaseous mixtures employing as an absorbent a liquid composition at least one of the components of which is chosen from the group consisting of ethanolamine, diethanolamine, and 3-methyl-3-amino-propane-diol-1,2.

  10. Lunar Elemental Abundances from Gamma-Ray and Neutron Measurements

    NASA Astrophysics Data System (ADS)

    Reedy, R. C.; Vaniman, D. T.

    1999-01-01

    The determination of elemental abundances is one of the highest science objectives of most lunar missions. Such multi-element abundances, ratios, or maps should include results for elements that are diagnostic or important in lunar processes, including heat-producing elements (such as K and Th), important incompatible elements (Th and rare earth elements), H (for polar deposits and regolith maturity), and key variable elements in major lunar provinces (such as Fe and Ti in the maria). Both neutron and gamma-ray spectroscopy can be used to infer elemental abundances; the two complement each other. These elemental abundances need to be determined with high accuracy and precision from measurements such as those made by the gamma-ray spectrometer (GRS) and neutron spectrometers (NS) on Lunar Prospector. As presented here, a series of steps, computer codes, and nuclear databases are needed to properly convert the raw gamma-ray and neutron measurements into good elemental abundances, ratios, and/or maps. Lunar Prospector (LP) is the first planetary mission that has measured neutrons escaping from a planet other than the Earth. The neutron spectrometers on Lunar Prospector measured a wide range of neutron energies. The ability to measure neutrons with thermal (E < 0.1 eV), epithermal (E about equal 0.1 - 1000 eV), and fast (E about 0.1-10 MeV) energies maximizes the scientific return, being especially sensitive to both H (using epithermal neutrons) and thermal-neutron-absorbing elements. Neutrons are made in the lunar surface by the interaction of galactic-cosmic-ray (GCR) particles with the atomic nuclei in the surface. Most neutrons are produced with energies above about 0.1 MeV. The flux of fast neutrons in and escaping from the Moon depends on es the intensity of the cosmic rays (which vary with solar activity) and the elemental composition of the surface. Variations in the elemental composition of the lunar surface can affect the flux of fast neutrons by about 25

  11. Improved Capture Gamma-Ray Libraries for Nuclear Applications

    NASA Astrophysics Data System (ADS)

    Sleaford, Brad; Firestone, Richard; Summers, Neil; Escher, Jutta

    2012-10-01

    The neutron capture reaction is of fundamental use in identifying and analyzing the gamma-ray spectrum from an unknown object as it gives unambiguous information on which isotopes are absorbing the neutrons. There are known data gaps in the ENDF libraries used by transport codes which are critical to various nuclear applications. The Evaluated Gamma-ray Activation file (EGAF) is a new thermal neutron capture database of discrete line spectra and cross sections for over 260 isotopes. This database is used to improve the capture gamma production in ENDF libraries. For medium to heavy nuclei the unresolved quasi continuum part of the gamma cascades are not experimentally available. This continuum can contain up to 90% of all the decay energy, in this work it is modeled with the statistical nuclear structure code Dicebox. We plan to continue the Dicebox approach through the resolved resonance region where spin and parity information is partially known. At higher energies to 20 MeV we are applying Hauser Feshbach models to predict the cross sections of gamma spectra to improve the neutron data libraries used for transport modeling of unknown objects.

  12. Measurement of activity concentrations of natural radionuclides in the topsoil of IITA Ibadan by gamma-ray spectrometry.

    PubMed

    Okeyode, I C; Farai, I P

    2007-09-01

    The activity concentrations of the natural radionuclides in the soils at the International Institute of Tropical Agriculture, (IITA), Idi-Ose, Moniya, Ibadan, Nigeria were investigated using a NaI (Tl) scintillation detector coupled with a Canberra series 10 plus multichannel analyser as the detecting device for gamma scintillation spectroscopy. The whole area was divided into grids and soil samples were collected from the points of intersection of the grids. The average activity concentrations obtained for the three radionuclides (40K, 238U and 232Th) were 180.08 +/- 90.54 Bq kg(-1) for 40K, 8.901 +/- 5.063 Bq kg(-1) for 238U and 11.01 +/- 7.686 Bq kg(-1) for 232Th. The average values of the absorbed dose rate for each radionuclide were found to be 7.33 nGy h(-1) for 232Th, 7.55 nGy h(-1) for 40K and 3.82 nGy h(-1) for 238U. The average (baseline) of the total absorbed dose rate was found to be 18.72 +/- 8.11 nGy h(-1). The baseline average outdoor annual effective dose equivalent at IITA due to the concentrations of the radionuclides was found to be 22.95 +/- 9.94 microSv y(-1). This value is low compared to the world average of 70 microSv y(-1) specified by UNSCEAR for an outdoor effective dose. Hence the probability of occurrence of any of the health effects of radiation is low.

  13. -G gamma A gamma-Thalassemia and gamma-chain variants in Chinese newborn babies.

    PubMed

    Zeng, Y T; Huang, S Z; Nakatsuji, T; Huisman, T H

    1985-03-01

    The occurrence of gamma-chain abnormal hemoglobins and of gamma-thalassemia in Chinese newborns was evaluated through analyses of the Hb F of over 1,100 babies and of the DNA from one baby and his parents. Gene mapping data identified this baby as a homozygote for -G gamma A gamma-thalassemia, which is caused by a deletion of about 5 kb due to an unequal crossing-over between the -G gamma- and -A gamma- genes. This condition is the same as that observed in Indian and Japanese babies [2,3]. Its gene frequency among babies from the Shanghai area was 0.012. A previously unrecognized G gamma chain variant, Hb F-Shanghai or alpha 2 G gamma 266(E10)Lys----Arg, was observed in one newborn. This variant was not detected by conventional techniques but only by high performance liquid chromatography, as the G gamma 66 Lys and G gamma 66 Arg chains had slightly different chromatographic mobilities. Lys at position gamma 66 participates in contacts with the heme group, and its substitution by another amino acid residue might interfere with physiochemical and/or functional properties. No other gamma-chain variants have been detected except the well-known A gamma T or F-Sardinia chain (f.A gamma T = 0.076).

  14. Simultaneous measurements of indoor radon, radon-thoron progeny and high-resolution gamma spectrometry in Greek dwellings.

    PubMed

    Clouvas, A; Xanthos, S; Antonopoulos-Domis, M

    2006-01-01

    Simultaneous indoor radon, radon-thoron progeny and high-resolution in situ gamma spectrometry measurements, with portable high-purity Ge detector were performed in 26 dwellings of Thessaloniki, the second largest town of Greece, during March 2003-January 2005. The radon gas was measured with an AlphaGUARD ionisation chamber (in each of the 26 dwellings) every 10 min, for a time period between 7 and 10 d. Most of the values of radon gas concentration are between 20 and 30 Bq m(-3), with an arithmetic mean of 34 Bq m(-3). The maximum measured value of radon gas concentration is 516 Bq m(-3). The comparison between the radon gas measurements, performed with AlphaGUARD and short-term electret ionisation chamber, shows very good agreement, taking into account the relative short time period of the measurement and the relative low radon gas concentration. Radon and thoron progeny were measured with a SILENA (model 4s) instrument. From the radon and radon progeny measurements, the equilibrium factor F could be deduced. Most of the measurements of the equilibrium factor are within the range 0.4-0.5. The mean value of the equilibrium factor F is 0.49 +/- 0.10, i.e. close to the typical value of 0.4 adopted by UNSCEAR. The mean equilibrium equivalent thoron concentration measured in the 26 dwellings is EEC(thoron) = 1.38 +/- 0.79 Bq m(-3). The mean equilibrium equivalent thoron to radon ratio concentration, measured in the 26 dwellings, is 0.1 +/- 0.06. The mean total absorbed dose rate in air, owing to gamma radiation, is 58 +/- 12 nGy h(-1). The contribution of the different radionuclides to the total indoor gamma dose rate in air is 38% due to 40K, 36% due to thorium series and 26% due to uranium series. The annual effective dose, due to the different source terms (radon, thoron and external gamma radiation), is 1.05, 0.39 and 0.28 mSv, respectively. PMID:16410290

  15. Absorbing layers for the Dirac equation

    SciTech Connect

    Pinaud, Olivier

    2015-05-15

    This work is devoted to the construction of perfectly matched layers (PML) for the Dirac equation, that not only arises in relativistic quantum mechanics but also in the dynamics of electrons in graphene or in topological insulators. While the resulting equations are stable at the continuous level, some care is necessary in order to obtain a stable scheme at the discrete level. This is related to the so-called fermion doubling problem. For this matter, we consider the numerical scheme introduced by Hammer et al. [19], and combine it with the discretized PML equations. We state some arguments for the stability of the resulting scheme, and perform simulations in two dimensions. The perfectly matched layers are shown to exhibit, in various configurations, superior absorption than the absorbing potential method and the so-called transport-like boundary conditions.

  16. Porous Carbon Nanoparticle Networks with Tunable Absorbability

    PubMed Central

    Dai, Wei; Kim, Seong Jin; Seong, Won-Kyeong; Kim, Sang Hoon; Lee, Kwang-Ryeol; Kim, Ho-Young; Moon, Myoung-Woon

    2013-01-01

    Porous carbon materials with high specific surface areas and superhydrophobicity have attracted much research interest due to their potential application in the areas of water filtration, water/oil separation, and oil-spill cleanup. Most reported superhydrophobic porous carbon materials are fabricated by complex processes involving the use of catalysts and high temperatures but with low throughput. Here, we present a facile single-step method for fabricating porous carbon nanoparticle (CNP) networks with selective absorbability for water and oils via the glow discharge of hydrocarbon plasma without a catalyst at room temperature. Porous CNP networks were grown by the continuous deposition of CNPs at a relatively high deposition pressure. By varying the fluorine content, the porous CNP networks exhibited tunable repellence against liquids with various degrees of surface tension. These porous CNP networks could be applied for the separation of not only water/oil mixtures but also mixtures of liquids with different surface tension levels. PMID:23982181

  17. Electromagnetic radiation absorbers and modulators comprising polyaniline

    DOEpatents

    Epstein, Arthur J.; Ginder, John M.; Roe, Mitchell G.; Hajiseyedjavadi, Hamid

    1992-01-01

    A composition for absorbing electromagnetic radiation, wherein said electromagnetic radiation possesses a wavelength generally in the range of from about 1000 Angstroms to about 50 meters, wherein said composition comprises a polyaniline composition of the formula ##STR1## where y can be equal to or greater than zero, and R.sup.1 and R.sup.2 are independently selected from the group containing of H, --OCH.sub.3, --CH.sub.3, --F, --Cl, --Br, --I, NR.sup.3 .sub.2, --NHCOR.sup.3, --OH, --O.sup.-, SR.sup.3, --OCOR.sup.3, --NO.sub.2, --COOH, --COOR.sup.3, --COR.sup.3, --CHO, and --CN, where R.sup.3 is a C.sub.1 to C.sub.8 alkyl, aryl or aralkyl group.

  18. Quasiperiodicity in lasers with saturable absorbers

    SciTech Connect

    Erneux, T.; Mandel, P.; Magnan, J.F.

    1984-05-01

    In this paper, we consider the mean-field equations for the laser with a saturable absorber (LSA) and concentrate on the low-intensity solutions. We show that the LSA equations may admit two successive bifurcations. The first bifurcation corresponds to the transition from the zero-intensity state to time-periodic intensities and is a Hopf bifurcation. The second bifurcation corresponds to the transition from these time-periodic intensities to quasiperiodic intensities which are characterized by two incommensurable frequencies. In order to describe these transitions, we investigate a particular limit of the parameters and propose a new perturbation method for solving the LSA equations. We give analytical conditions for the existence of both the primary and secondary bifurcations.

  19. Porous carbon nanoparticle networks with tunable absorbability.

    PubMed

    Dai, Wei; Kim, Seong Jin; Seong, Won-Kyeong; Kim, Sang Hoon; Lee, Kwang-Ryeol; Kim, Ho-Young; Moon, Myoung-Woon

    2013-01-01

    Porous carbon materials with high specific surface areas and superhydrophobicity have attracted much research interest due to their potential application in the areas of water filtration, water/oil separation, and oil-spill cleanup. Most reported superhydrophobic porous carbon materials are fabricated by complex processes involving the use of catalysts and high temperatures but with low throughput. Here, we present a facile single-step method for fabricating porous carbon nanoparticle (CNP) networks with selective absorbability for water and oils via the glow discharge of hydrocarbon plasma without a catalyst at room temperature. Porous CNP networks were grown by the continuous deposition of CNPs at a relatively high deposition pressure. By varying the fluorine content, the porous CNP networks exhibited tunable repellence against liquids with various degrees of surface tension. These porous CNP networks could be applied for the separation of not only water/oil mixtures but also mixtures of liquids with different surface tension levels. PMID:23982181

  20. Porous Carbon Nanoparticle Networks with Tunable Absorbability

    NASA Astrophysics Data System (ADS)

    Dai, Wei; Kim, Seong Jin; Seong, Won-Kyeong; Kim, Sang Hoon; Lee, Kwang-Ryeol; Kim, Ho-Young; Moon, Myoung-Woon

    2013-08-01

    Porous carbon materials with high specific surface areas and superhydrophobicity have attracted much research interest due to their potential application in the areas of water filtration, water/oil separation, and oil-spill cleanup. Most reported superhydrophobic porous carbon materials are fabricated by complex processes involving the use of catalysts and high temperatures but with low throughput. Here, we present a facile single-step method for fabricating porous carbon nanoparticle (CNP) networks with selective absorbability for water and oils via the glow discharge of hydrocarbon plasma without a catalyst at room temperature. Porous CNP networks were grown by the continuous deposition of CNPs at a relatively high deposition pressure. By varying the fluorine content, the porous CNP networks exhibited tunable repellence against liquids with various degrees of surface tension. These porous CNP networks could be applied for the separation of not only water/oil mixtures but also mixtures of liquids with different surface tension levels.

  1. Light-absorbing impurities in Arctic snow

    NASA Astrophysics Data System (ADS)

    Doherty, S. J.; Warren, S. G.; Grenfell, T. C.; Clarke, A. D.; Brandt, R. E.

    2010-12-01

    Absorption of radiation by ice is extremely weak at visible and near-ultraviolet wavelengths, so small amounts of light-absorbing impurities in snow can dominate the absorption of solar radiation at these wavelengths, reducing the albedo relative to that of pure snow, contributing to the surface energy budget and leading to earlier snowmelt. In this study Arctic snow is surveyed for its content of light-absorbing impurities, expanding and updating the 1983-1984 survey of Clarke and Noone. Samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean during 1998 and 2005-2009, on tundra, glaciers, ice caps, sea ice, frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack is accessible for sampling. Sampling was carried out in summer on the Greenland Ice Sheet and on the Arctic Ocean, of melting glacier snow and sea ice as well as cold snow. About 1200 snow samples have been analyzed for this study. The snow is melted and filtered; the filters are analyzed in a specially designed spectrophotometer system to infer the concentration of black carbon (BC), the fraction of absorption due to non-BC light-absorbing constituents and the absorption Ångstrom exponent of all particles. This is done using BC calibration standards having a mass absorption efficiency of 6.0 m2 g-1 at 550 nm and by making an assumption that the absorption Angstrom exponent for BC is 1.0 and for non-BC light-absorbing aerosol is 5.0. The reduction of snow albedo is primarily due to BC, but other impurities, principally brown (organic) carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. The meltwater from selected snow samples was saved for chemical analysis to identify sources of the impurities. Median BC amounts in surface snow are as follows (nanograms of carbon per gram of snow): Greenland 3, Arctic Ocean snow 7, melting sea ice 8, Arctic Canada 8, subarctic Canada 14

  2. Microcellular ceramic foams for radar absorbing structures

    SciTech Connect

    Huling, J.; Phillips, D.

    1996-09-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of this project is to develop a lightweight, semi-structural, radar-absorbing ceramic foam that can be incorporated into aircraft exhaust systems to replace many of the currently used dense ceramic parts and thereby improve the radar cross section. Although the conventional processes for producing ceramic foams have not been able to provide materials that meet the design specifications for high strength at low density, we have developed and demonstrated a novel sol-gel emulsion process for preparing microcellular ceramic foams in which compositional and microstructural control is expected to provide the requisite high-temperature radar-absorption, strength-to-weight ratio, and thermal insulative properties.

  3. Cusps, self-organization, and absorbing states.

    PubMed

    Bonachela, Juan A; Alava, Mikko; Muñoz, Miguel A

    2009-05-01

    Elastic interfaces embedded in (quenched) random media exhibit metastability and stick-slip dynamics. These nontrivial dynamical features have been shown to be associated with cusp singularities of the coarse-grained disorder correlator. Here we show that annealed systems with many absorbing states and a conservation law but no quenched disorder exhibit identical cusps. On the other hand, similar nonconserved systems in the directed percolation class are also shown to exhibit cusps but of a different type. These results are obtained both by a recent method to explicitly measure disorder correlators and by defining an alternative new protocol inspired by self-organized criticality, which opens the door to easily accessible experimental realizations.

  4. Measurement of the gamma gamma* --> eta and gamma gamma* --> eta' transition form factors

    SciTech Connect

    del Amo Sanchez et al, P.

    2011-02-07

    We study the reactions e{sup +}e{sup -} {yields} e{sup +}e{sup -} {eta}{sup (/)} in the single-tag mode and measure the {gamma}{gamma}* {yields} {eta}{sup (/)} transition form factors in the momentum transfer range from 4 to 40 GeV{sup 2}. The analysis is based on 469 fb{sup -1} of integrated luminosity collected at PEP-II with the BABAR detector at e{sup +}e{sup -} center-of-mass energies near 10.6 GeV.

  5. Gamma-ray bursts.

    PubMed

    Gehrels, Neil; Mészáros, Péter

    2012-08-24

    Gamma-ray bursts (GRBs) are bright flashes of gamma rays coming from the cosmos. They occur roughly once per day, typically last for tens of seconds, and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this Review, we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglow. PMID:22923573

  6. Gamma camera purchasing.

    PubMed

    Wells, C P; Buxton-Thomas, M

    1995-03-01

    The purchase of a new gamma camera is a major undertaking and represents a long-term commitment for most nuclear medicine departments. The purpose of tendering for gamma cameras is to assess the best match between the requirements of the clinical department and the equipment available and not necessarily to buy the 'best camera' [1-3]. After many years of drawing up tender specifications, this paper tries to outline some of the traps and pitfalls of this potentially perilous, although largely rewarding, exercise. PMID:7770241

  7. Clearance of absorbed selenium by the liver

    SciTech Connect

    Kato, Tatsuko; Read, R.; Rozga, J.; Burk, R.F. )

    1991-03-11

    The liver plays a central role in the metabolism of selenium. It secretes plasma selenoproteins, contains a major fraction of the glutathione peroxidase in the body, and synthesizes excretory metabolites. The role of the liver in processing newly absorbed selenium was studied. Male chow-fed rats were fasted overnight and given 24 ng of selenium as {sup 75}SeO{sub 3}{sup 2{minus}} by stomach tube. Animals were exsanguinated at 15, 30, 45, 60, 90, 120, and 180 min after dosing. Comparison of {sup 75}Se uptake by liver, kidney, heart, muscle, testis, brain, and spleen indicated an earlier uptake by liver than by any other tissue. At 15 min, {sup 75}Se in the portal vein blood was 2.6 times that in the hepatic vein blood. Gel filtration analysis suggested a loose association of {sup 75}Se with protein in plasma at 15 min, but immunoprecipitation indicated it was largely in the form of selenoprotein P after 30 min. End-to-side portacaval shunts (PCS) were constructed in rats and sham-operated animals were used as controls. When {sup 75}SeO{sub 3}{sup 2{minus}} was given to animals with PCS, uptake of {sup 75}Se by liver did not precede uptake by other tissues. Also no gradient was detected across the lungs or kidney. {sup 75}Se content of the kidney was higher in PCS rats than in sham-operated rats. This is consistent with removal of the first-pass effect of the liver facilitating uptake of {sup 75}Se by systemic tissues. These results suggest that the preferential uptake of absorbed selenium by the liver is due both to its position in the portal circulation and to an intrinsic high uptake capacity.

  8. Light Absorbing Aerosols in Mexico City

    NASA Astrophysics Data System (ADS)

    Marley, N. A.; Kelley, K. L.; Kilaparty, P. S.; Gaffney, J. S.

    2008-12-01

    The direct effects of aerosol radiative forcing has been identified by the IPCC as a major uncertainty in climate modeling. The DOE Megacity Aerosol Experiment-Mexico City (MAX-Mex), as part of the MILAGRO study in March of 2006, was undertaken to reduce these uncertainties by characterization of the optical, chemical, and physical properties of atmospheric aerosols emitted from this megacity environment. Aerosol samples collected during this study using quartz filters were characterized in the uv-visible-infrared by using surface spectroscopic techniques. These included the use of an integrating sphere approach combined with the use of Kubelka-Munk theory to obtain aerosol absorption spectra. In past work black carbon has been assumed to be the only major absorbing species in atmospheric aerosols with an broad band spectral profile that follows a simple inverse wavelength dependence. Recent work has also identified a number of other absorbing species that can also add to the overall aerosol absorption. These include primary organics from biomass and trash burning and secondary organic aerosols including nitrated PAHs and humic-like substances, or HULIS. By using surface diffuse reflection spectroscopy we have also obtained spectra in the infrared that indicate significant IR absorption in the atmospheric window-region. These data will be presented and compared to spectra of model compounds that allow for evaluation of the potential importance of these species in adding strength to the direct radiative forcing of atmospheric aerosols. This work was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-07ER64327 as part of the Atmospheric Science Program.

  9. [Degradation of 3-chlorophenol in aqueous solution by combined process of gamma-radiation and H2O2].

    PubMed

    Hu, Jun; Wang, Jian-long

    2009-10-15

    The radiolytical degradation of 3-chlorophenol (3-CP) in aqueous solution was investigated using gamma-radiation and gamma-radiation/hydrogen peroxide (H2O2) combined process. The effect of absorbed dose, initial concentration of 3-CP and addition of H2O2 on pollutant degradation, dechlorination and the degree of mineralization was studied by measuring the removal efficiency of 3-CP, the variation of total organic carbon (TOC), the dechlorination rate, and the absorbance spectrum of vis-UV. The kinetics of 3-CP degradation was also discussed. The results showed that when 3-CP concentration was 10 mg x L(-1) and the absorbed dose was 2 kGy, the dechlorination rate reached 100%, the TOC removal efficiency was 53%; when the absorbed dose increased to 8 kGy, 3-CP could be completely mineralized and the TOC removal efficiency reached 100%. The radiolysis of 3-CP could be described by one-order reaction kinetics, there existed synergic effect for combined process of gamma-irradiation/hydrogen peroxide for 3-CP degradation. The rate constant of 3-CP degradation for gamma-radiation and gamma-radiation/hydrogen peroxide combined process was 0.279 h(-1) and 0.542 h(-1), respectively.

  10. Measurement of natural radioactivity in Jordanian building materials and their contribution to the public indoor gamma dose rate.

    PubMed

    Sharaf, J M; Hamideen, M S

    2013-10-01

    This study is undertaken to determine the activity concentration of (226)Ra, (232)Th and (40)K in samples of commonly used building materials in Jordan. Samples of seven different materials were collected from construction sites and local agencies supplying raw construction materials and analyzed using a HPGe gamma-ray spectrometer, taking into account self-attenuation in bulk samples. The average specific activity concentrations of (226)Ra, (232)Th, and (40)K ranged from 2.84 to 41.52, 0.78 to 58.42. and 3.74 to 897 Bq/kg, respectively. All the samples had radium equivalent activities well below the limit of 370 Bq/kg set by the Organization for Economic Cooperation and Development (OECD, 1979). External and internal hazard indices, absorbed dose and annual effective dose rate associated with the radionuclides of interest were calculated and compared with the international legislation and guidance. In general, most of the activities did not exceed the recommended international limits, except for granite and ceramic samples which are usually used as secondary building materials in Jordan. PMID:23831927

  11. Measurement of natural radioactivity in Jordanian building materials and their contribution to the public indoor gamma dose rate.

    PubMed

    Sharaf, J M; Hamideen, M S

    2013-10-01

    This study is undertaken to determine the activity concentration of (226)Ra, (232)Th and (40)K in samples of commonly used building materials in Jordan. Samples of seven different materials were collected from construction sites and local agencies supplying raw construction materials and analyzed using a HPGe gamma-ray spectrometer, taking into account self-attenuation in bulk samples. The average specific activity concentrations of (226)Ra, (232)Th, and (40)K ranged from 2.84 to 41.52, 0.78 to 58.42. and 3.74 to 897 Bq/kg, respectively. All the samples had radium equivalent activities well below the limit of 370 Bq/kg set by the Organization for Economic Cooperation and Development (OECD, 1979). External and internal hazard indices, absorbed dose and annual effective dose rate associated with the radionuclides of interest were calculated and compared with the international legislation and guidance. In general, most of the activities did not exceed the recommended international limits, except for granite and ceramic samples which are usually used as secondary building materials in Jordan.

  12. Gamma-Ray Sterilization of Mars Analog Rocks and Minerals

    NASA Astrophysics Data System (ADS)

    Allen, C. C.

    1998-01-01

    Samples of rock and soil, collected by robotic spacecraft on Mars, will be returned to terrestrial laboratories early in the next century. Plans call for the samples to be placed immediately in biological containment and tested for signs of present or past life and biological hazard. It is recommended that "controlled distribution of unsterilized materials from Mars should occur only if rigorous analyses determine that the materials do not constitute a biological hazard. If any portion of the sample is removed from containment prior to completion of these analyses it should first be sterilized." While sterilization of Mars samples may not be required, an acceptable method must be available before the samples are returned to Earth. Various techniques are routinely used to sterilize biological samples. These include dry heating to temperatures of 150C or higher, heating in the presence of steam, exposure to poisonous gases such as formaldehyde and propiolactone, exposure to H2O2 vapor or plasma, exposure to ultraviolet light, and exposure to gamma radiation. The appropriate technique depends on the physical characteristics of the sample and the desired results. Gamma radiation is routinely used to inactivate viruses and destroy bacteria in medical research. The most commercial sterilizers use Cobalt 60, which emits gamma photons with energies of 1. 173 and 1. 332 MeV. Absorbed doses of approximately 106 rad (104 gamma ray is equal to 104 ergs/gm) are sufficient to destroy most bacteria. The current study is designed to investigate the effects of lethal doses of Cobalt 60 gamma radiation on geologic materials analogous to the first samples to be returned from Mars. The goals are (1) to determine the gamma ray dose required to kill microorganisms within geologic samples, and (2) to determine the effects of lethal doses of gamma radiation on the physical and chemical properties of the samples.

  13. Radiation Sterilization and Food Irradiation Using Gamma Radiation

    NASA Astrophysics Data System (ADS)

    O'Hara, Kevin

    2003-03-01

    Since the introduction of MDS Nordion's first irradiator in the early 1960's, a variety of gamma-processing systems has been developed. Each design is suited to a particular set of requirements - from high-throughput operations of diverse product lots to full automation or batch processing, all using gamma radiation. Gamma irradiator designs include the Centurion irradiator for temperature-sensitive food products like hamburgers and poultry; the Brevion, a compact batch irradiator providing flexibility, timeliness and simplicity on a whole new scale; a JS-10000 irradiator that operates in either automatic or batch mode to enable multipurpose product scheduling and optimum throughput; and, an irradiator that processes full pallets and is ideal for processing high-density products requiring excellent dose uniformity. These innovative irradiator designs help facilities to be more efficient, maximize operating time, improve product turnaround and minimize inventory levels. MDS Nordion's development of improved Point Kernel and Monte Carlo techniques is discussed, including their application in radiation source optimization, production irradiator design and process control. Absorbed-dose calculations also provide insight into the critical areas for dose mapping and routine monitoring, allowing for the optimum placement of dosimeters. Calculations may also be used to determine the absorbed-dose distribution within product, especially in areas of complex geometry such as material interfaces. The use of easily accessible, accurate and validated dose-calculation programs can be used to optimize the irradiation process. Key Words: dosimetry, irradiator design, dose calculation, modelling, modeling, process control, radiation source optimization.

  14. Evaluation of selective solar-absorber surfaces. Semi-annual report, March 25-September 24, 1981

    SciTech Connect

    Osiecki, R.A.

    1981-10-01

    The goals of the study reported are: to induce the degradation of the optical properties of selected samples of surface finishes by exposing them to a high humidity/high temperature environment for extended periods of time; and to analyze the degraded and non-degraded surface finishes to determine the operative degradation mechanism in each surface finish. The eight surface finishes tested include: black chrome on aluminum, on copper, and on nickel-plated copper; copper oxide/copper on mild steel; nickel-chromium oxide on nickel foil; a chromate conversion coating; and a thickness sensitive, silicone based paint. Values of the spectral reflectance, absorptance, and emittance are presented for degraded samples. Surface analysis is reported complete for some of the samples. (LEW)

  15. Iron K Lines from Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Kallman, T. R.; Meszaros, P.; Rees, M. J.

    2003-01-01

    We present models for reprocessing of an intense flux of X-rays and gamma rays expected in the vicinity of gamma ray burst sources. We consider the transfer and reprocessing of the energetic photons into observable features in the X-ray band, notably the K lines of iron. Our models are based on the assumption that the gas is sufficiently dense to allow the microphysical processes to be in a steady state, thus allowing efficient line emission with modest reprocessing mass and elemental abundances ranging from solar to moderately enriched. We show that the reprocessing is enhanced by down-Comptonization of photons whose energy would otherwise be too high to absorb on iron, and that pair production can have an effect on enhancing the line production. Both "distant" reprocessors such as supernova or wind remnants and "nearby" reprocessors such as outer stellar envelopes can reproduce the observed line fluxes with Fe abundances 30-100 times above solar, depending on the incidence angle. The high incidence angles required arise naturally only in nearby models, which for plausible values can reach Fe line to continuum ratios close to the reported values.

  16. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1991-01-01

    Miscellaneous tasks related to the development of the Burst and Transient Source Experiment on the Gamma Ray Observatory and to collection, analysis, and interpretation of data from the MSFC Very Low Frequency transient monitoring program were performed. The results are summarized and relevant references are included.

  17. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1992-01-01

    Miscellaneous tasks related to mission operations and data analysis for the Burst and Transient Source Experiment on the Gamma Ray Observatory, to collection, analysis, and interpretation of data from the Marshall Space Flight Center Very Low Frequency transient monitoring program, and to compilation and analysis of induced radioactivity data were performed. The results are summarized and relevant references are included.

  18. Celestial gamma ray study

    NASA Technical Reports Server (NTRS)

    Michelson, Peter F.

    1995-01-01

    This report documents the research activities performed by Stanford University investigators as part of the data reduction effort and overall support of the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Observatory. This report is arranged chronologically, with each subsection detailing activities during roughly a one year period of time, beginning in June 1991.

  19. Application of airborne gamma spectrometric survey data to estimating terrestrial gamma-ray dose rates: an example in California.

    PubMed

    Wollenberg, H A; Revzan, K L; Smith, A R

    1994-01-01

    We examined the applicability of radioelement data from the National Aerial Radiometric Reconnaissance, an element of the National Uranium Resource Evaluation, to estimate terrestrial gamma-ray absorbed dose rates, by comparing dose rates calculated from aeroradiometric surveys of uranium, thorium, and potassium concentrations with dose rates calculated from a radiogeologic data base and the distribution of lithologies in California. Gamma-ray dose rates increase generally from north to south following lithological trends, with low values of 25-30 nGy h-1 in the northernmost 1 x 2 degrees quadrangles between 41 and 42 degrees N to high values of 75-100 nGy h-1 in southeastern California. Lithologic-based estimates of mean dose rates in the quadrangles generally match those from aeroradiometric data, with statewide means of 63 and 60 nGy h-1, respectively. These are intermediate between a population-weighted global average of 51 nGy h-1 reported in 1982 by UNSCEAR and a weighted continental average of 70 nGy h-1, based on the global distribution of rock types. The concurrence of lithologically and aeroradiometrically determined dose rates in California, with its varied geology and topography encompassing settings representative of the continents, indicates that the National Aerial Radiometric Reconnaissance data are applicable to estimates of terrestrial absorbed dose rates from natural gamma emitters.

  20. Gamma ray astronomy in perspective

    NASA Technical Reports Server (NTRS)

    1981-01-01

    A brief overview of the development of gamma ray astronomy is presented. Gamma ray telescopes and other optical measuring instruments are highlighted. Emphasis is placed on findings that were unobtainable before gamma ray astronomy. Information on evolution of the solar system, the relationship of the solar system to the galaxy, and the composition of interstellar matter is discussed.

  1. pi {sup 0} {yields} gamma gamma to NLO in CHPT

    SciTech Connect

    Jose Goity

    2003-05-01

    The pi 0 {yields} gamma gamma width is determined to next to leading order in the combined chiral and 1/Nc expansions. It is shown that corrections driven by chiral symmetry breaking produce an enhancement of about 4.5% with respect to the width calculated in terms of the chiral-limit amplitude leading to Gamma{sub {pi}}{sup 0} {yields} {gamma}{gamma} = 8.1 +/- 0.08 MeV. This theoretical prediction will be tested via pi 0 Primakoff production by the PRIMEX experiment at Jefferson Lab.

  2. Annual Fund. Estate Planning.

    ERIC Educational Resources Information Center

    Stuhr, Robert L.; Jarc, Jerry A.

    The first of a series, this publication consists of two symposium presentations. The first paper, "Annual Fund: Cornerstone of Development," by Robert L. Stuhr, defines the annual fund concept in the context of institutional development and provides five requisites for a successful annual fund: it must (1) be part of an ongoing development…

  3. Estimation of surface melt and absorbed radiation on the Greenland ice sheet using passive microwave data

    NASA Astrophysics Data System (ADS)

    Joshi, Maneesha D.

    1999-09-01

    Passive microwave data from the Defense Meteorological Satellite Program (DMPS) Special Sensor Microwave/Imager (SSM/I) and Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) were used to estimate the extent of melt, melt duration and length of melt season on the Greenland ice sheet for the years 1979--1997. Three techniques---a maximum likelihood classification (MLC), a spectral technique and an edge detection method---were implemented. The MLC and spectral techniques provided estimates of the melt extent, while estimates of the melt extent, the length of the melt season and the duration of melt were obtained from the edge method. Comparisons of the surface melt results with global and coastal (Greenland) temperature data indicated that melt extents were better related to global than coastal temperatures. The reverse was noted for melt season and duration trends. The results suggest an overall increase in warmer spells in summer for the period 1979--1997, as indicated by increasing maximum melt extent on the ice sheet. However, there was no corresponding increase in the overall total melt season and total duration of melt. The annual melt extent and the total melt season/duration showed a sharp drop in 1992, due to the eruption of Mt. Pinatubo in June, 1991. The results indicated that melt extents alone cannot be used to estimate warming or cooling on the ice sheet and that melt duration and season trends should also be examined. These surface melt results were then extended to obtain the absorbed radiation flux on the Greenland ice sheet. The monthly albedo on the ice sheet was estimated by assigning an albedo value that was a function of the length of the melt season. The monthly albedo was used with a solar radiation model to estimate the monthly and annual absorbed shortwave flux on the ice sheet. The computation of absorbed radiation on the Greenland ice sheet gave results consistent with those derived from the Earth Radiation Budget Experiment (ERBE

  4. Measurement and Simulation Results of Ti Coated Microwave Absorber

    SciTech Connect

    Sun, Ding; McGinnis, Dave; /Fermilab

    1998-11-01

    When microwave absorbers are put in a waveguide, a layer of resistive coating can change the distribution of the E-M fields and affect the attenuation of the signal within the microwave absorbers. In order to study such effect, microwave absorbers (TT2-111) were coated with titanium thin film. This report is a document on the coating process and measurement results. The measurement results have been used to check the simulation results from commercial software HFSS (High Frequency Structure Simulator.)

  5. Optoacoustic control of laser energy absorbed inside tissue

    NASA Astrophysics Data System (ADS)

    Genina, Elina A.; Lapin, Sergey A.; Petrov, Vladimir V.; Tuchin, Valery V.

    2001-06-01

    Monitoring of laser energy absorbed inside tissue is very impotent for laser thermocoagulation of tumors, laser surgery etc. Experimental results have shown that analysis of optoacoustic signal magnitude induced by short laser pulse inside tissue can give quantitative information about laser fluence absorbed by the tissue. We have investigated some tissue phantoms with absorbing objects inside. The first harmonic (1064 nm) of Q-switched Nd:YAG-laser was used for generation of optoacoustic signals.

  6. Vertical-plane pendulum absorbers for minimizing helicopter vibratory loads

    NASA Technical Reports Server (NTRS)

    Amer, K. B.; Neff, J. R.

    1974-01-01

    The use of pendulum dynamic absorbers mounted on the blade root and operating in the vertical plane to minimize helicopter vibratory loads was discussed. A qualitative description was given of the concept of the dynamic absorbers and some results of analytical studies showing the degree of reduction in vibratory loads attainable are presented. Operational experience of vertical plane dynamic absorbers on the OH-6A helicopter is also discussed.

  7. Refractory plasmonics with titanium nitride: broadband metamaterial absorber.

    PubMed

    Li, Wei; Guler, Urcan; Kinsey, Nathaniel; Naik, Gururaj V; Boltasseva, Alexandra; Guan, Jianguo; Shalaev, Vladimir M; Kildishev, Alexander V

    2014-12-17

    A high-temperature stable broadband plasmonic absorber is designed, fabricated, and optically characterized. A broadband absorber with an average high absorption of 95% and a total thickness of 240 nm is fabricated, using a refractory plasmonic material, titanium nitride. This absorber integrates both the plasmonic resonances and the dielectric-like loss. It opens a path for the interesting applications such as solar thermophotovoltaics and optical circuits.

  8. Gamma doses from phospho-gypsum plaster-board.

    PubMed

    O'Brien, R S

    1997-01-01

    The use of phospho-gypsum plaster-board and plaster cement in buildings as a substitute for natural gypsum may constitute an additional source of radiation exposure to both workers and members of the public, both from inhalation of radon progeny produced from radon which is exhaled from the plaster-board and from beta and gamma radiation produced by radioactive decay in the plaster-board. The calculations presented in this paper indicate that if phospho-gypsum sheets 1 cm thick containing a 226Ra concentration of 400 Bq kg(-1) are used to line the walls and ceiling of a room of dimensions up to 5 m x 5 m x 3 m, the annual effective dose from gamma radiation for a person continually occupying the room should not exceed approximately 0.13 mSv. This compares with a measured annual average effective dose from gamma radiation in Australian homes of 0.9 mSv. The annual effective dose from such thin sheets is directly proportional to the 226Ra concentration in the plaster-board.

  9. Microscopic analysis of saturable absorbers: Semiconductor saturable absorber mirrors versus graphene

    NASA Astrophysics Data System (ADS)

    Hader, J.; Yang, H.-J.; Scheller, M.; Moloney, J. V.; Koch, S. W.

    2016-02-01

    Fully microscopic many-body calculations are used to study the influence of strong sub-picosecond pulses on the carrier distributions and corresponding optical response in saturable absorbers used for mode-locking—semiconductor (quantum well) saturable absorber mirrors (SESAMs) and single layer graphene based saturable absorber mirrors (GSAMs). Unlike in GSAMs, the saturation fluence and recovery time in SESAMs show a strong spectral dependence. While the saturation fluence in the SESAM is minimal at the excitonic bandgap, the optimal recovery time and least pulse distortion due to group delay dispersion are found for excitation higher in the first subband. For excitation near the SESAM bandgap, the saturation fluence is about one tenth of that in the GSAM. At energies above the bandgap, the fluences in both systems become similar. A strong dependence of the saturation fluence on the pulse width in both systems is caused by carrier relaxation during the pulse. The recovery time in graphene is found to be about two to four times faster than that in the SESAMs. The occurrence of negative differential transmission in graphene is shown to be caused by dopant related carriers. In SESAMs, a negative differential transmission is found when exciting below the excitonic resonance where excitation induced dephasing leads to an enhancement of the absorption. Comparisons of the simulation data to the experiment show a very good quantitative agreement.

  10. PRECISE {gamma}-RAY TIMING AND RADIO OBSERVATIONS OF 17 FERMI {gamma}-RAY PULSARS

    SciTech Connect

    Ray, P. S.; Wolff, M. T.; Grove, J. E.; Gwon, C.; Kerr, M.; Parent, D.; Makeev, A.; Abdo, A. A.; Guillemot, L.; Freire, P. C. C.; Kramer, M.; Ransom, S. M.; Rea, N.; Roberts, M. S. E.; Camilo, F.; Dormody, M.; Harding, A. K.; Johnston, S.; Keith, M.; Michelson, P. F.

    2011-06-01

    We present precise phase-connected pulse timing solutions for 16 {gamma}-ray-selected pulsars recently discovered using the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope plus one very faint radio pulsar (PSR J1124-5916) that is more effectively timed with the LAT. We describe the analysis techniques including a maximum likelihood method for determining pulse times of arrival from unbinned photon data. A major result of this work is improved position determinations, which are crucial for multiwavelength follow-up. For most of the pulsars, we overlay the timing localizations on X-ray images from Swift and describe the status of X-ray counterpart associations. We report glitches measured in PSRs J0007+7303, J1124-5916, and J1813-1246. We analyze a new 20 ks Chandra ACIS observation of PSR J0633+0632 that reveals an arcminute-scale X-ray nebula extending to the south of the pulsar. We were also able to precisely localize the X-ray point source counterpart to the pulsar and find a spectrum that can be described by an absorbed blackbody or neutron star atmosphere with a hard power-law component. Another Chandra ACIS image of PSR J1732-3131 reveals a faint X-ray point source at a location consistent with the timing position of the pulsar. Finally, we present a compilation of new and archival searches for radio pulsations from each of the {gamma}-ray-selected pulsars as well as a new Parkes radio observation of PSR J1124-5916 to establish the {gamma}-ray to radio phase offset.

  11. Optimal active vibration absorber: Design and experimental results

    NASA Technical Reports Server (NTRS)

    Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

    1992-01-01

    An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

  12. Decomposition-based recovery of absorbers in turbid media

    SciTech Connect

    Campbell, S. D.; Goodin, I. L.; Grobe, S. D.; Su, Q.; Grobe, R.

    2007-12-15

    We suggest that the concept of the point-spread function traditionally used to predict the blurred image pattern of various light sources embedded inside turbid media can be generalized under certain conditions to predict also the presence and location of spatially localized absorbing inhomogeneities based on shadow point-spread functions associated with each localized absorber in the medium. The combined image obtained from several absorbers can then be decomposed approximately into the arithmetic sums of these individual shadow point-spread functions with suitable weights that can be obtained from multiple-regression analysis. This technique permits the reconstruction of the location of absorbers.

  13. Tunable microwave metamaterial absorbers using varactor-loaded split loops

    NASA Astrophysics Data System (ADS)

    Zhu, Jinfeng; Li, Delong; Yan, Shuang; Cai, Yijun; Huo Liu, Qing; Lin, Timothy

    2015-12-01

    Currently, implementation of active circuit elements within metamaterials is an effective way to make them electrically tunable. We combine varactors with split copper loops in a metamaterial absorber in order to obtain an electrically tunable microwave response. This absorber has a compact planar structure and a simplified back feeding network. Flexible frequency tunability of the microwave reflection in the range of 5-6 GHz is experimentally achieved. The design, simulation, and experimental results are systematically presented. The proposed method is scalable for developing active metamaterial absorbers based on metal loops, and shows a promising potential of active metamaterial absorbers for extensive microwave applications.

  14. Dual band metamaterial perfect absorber based on artificial dielectric "molecules".

    PubMed

    Liu, Xiaoming; Lan, Chuwen; Li, Bo; Zhao, Qian; Zhou, Ji

    2016-01-01

    Dual band metamaterial perfect absorbers with two absorption bands are highly desirable because of their potential application areas such as detectors, transceiver system, and spectroscopic imagers. However, most of these dual band metamaterial absorbers proposed were based on resonances of metal patterns. Here, we numerically and experimentally demonstrate a dual band metamaterial perfect absorber composed of artificial dielectric "molecules" with high symmetry. The artificial dielectric "molecule" consists of four "atoms" of two different sizes corresponding to two absorption bands with near unity absorptivity. Numerical and experimental absorptivity verify that the dual-band metamaterial absorber is polarization insensitive and can operate in wide-angle incidence. PMID:27406699

  15. The GAMMA-400 gamma-ray telescope for precision gamma-ray emission investigations

    NASA Astrophysics Data System (ADS)

    Topchiev, N. P.; Galper, A. M.; Bonvicini, V.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Bakaldin, A. V.; Bergstrom, L.; Berti, E.; Bigongiari, G.; Bobkov, S. G.; Boezio, M.; Bogomolov, E. A.; Bonechi, L.; Bongi, M.; Bottai, S.; Castellini, G.; Cattaneo, P. W.; Cumani, P.; Dalkarov, O. D.; Dedenko, G. L.; De Donato, C.; Dogiel, V. A.; Finetti, N.; Gascon, D.; Gorbunov, M. S.; Gusakov, Yu V.; Hnatyk, B. I.; Kadilin, V. V.; Kaplin, V. A.; Kaplun, A. A.; Kheymits, M. D.; Korepanov, V. E.; Larsson, J.; Leonov, A. A.; Loginov, V. A.; Longo, F.; Maestro, P.; Marrocchesi, P. S.; Martinez, M.; Men'shenin, A. L.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu; Papini, P.; Paredes, J. M.; Pearce, M.; Picozza, P.; Rappoldi, A.; Ricciarini, S.; Runtso, M. F.; Ryde, F.; Serdin, O. V.; Sparvoli, R.; Spillantini, P.; Stozhkov, Yu I.; Suchkov, S. I.; Taraskin, A. A.; Tavani, M.; Tiberio, A.; Tyurin, E. M.; Ulanov, M. V.; Vacchi, A.; Vannuccini, E.; Vasilyev, G. I.; Ward, J. E.; Yurkin, Yu T.; Zampa, N.; Zirakashvili, V. N.; Zverev, V. G.

    2016-02-01

    The GAMMA-400 gamma-ray telescope with excellent angular and energy resolutions is designed to search for signatures of dark matter in the fluxes of gamma-ray emission and electrons + positrons. Precision investigations of gamma-ray emission from Galactic Center, Crab, Vela, Cygnus, Geminga, and other regions will be performed, as well as diffuse gamma-ray emission, along with measurements of high-energy electron + positron and nuclei fluxes. Furthermore, it will study gamma-ray bursts and gamma-ray emission from the Sun during periods of solar activity. The GAMMA-400 energy range is expected to be from ∼20 MeV up to TeV energies for gamma rays, up to 10 TeV for electrons + positrons, and up to 1015 eV for cosmic-ray nuclei. For 100-GeV gamma rays, the GAMMA-400 angular resolution is ∼0.01° and energy resolution is ∼1% the proton rejection factor is ∼5x105. GAMMA-400 will be installed onboard the Russian space observatory.

  16. Topics in gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1986-01-01

    Observations of gamma rays from solar flares, gamma ray bursts, the Galactic center, galactic nucleosynthesis, SS433, and Cygnus X-3, and their effects on astrophysical problems are discussed. It is observed that gamma ray spectra from solar flares are applicable to the study of particle acceleration and confinement and the determination of chemical abundances in the solar atmosphere. The gamma ray lines from the compact galactic object SS433 are utilized to examine the acceleration of jets, and analysis of the gamma ray lines of Cygnus X-3 reveal that particles can be accelerated in compact sources to ultrahigh energies.

  17. Hot Carrier Extraction with Plasmonic Broadband Absorbers.

    PubMed

    Ng, Charlene; Cadusch, Jasper J; Dligatch, Svetlana; Roberts, Ann; Davis, Timothy J; Mulvaney, Paul; Gómez, Daniel E

    2016-04-26

    Hot charge carrier extraction from metallic nanostructures is a very promising approach for applications in photocatalysis, photovoltaics, and photodetection. One limitation is that many metallic nanostructures support a single plasmon resonance thus restricting the light-to-charge-carrier activity to a spectral band. Here we demonstrate that a monolayer of plasmonic nanoparticles can be assembled on a multistack layered configuration to achieve broadband, near-unit light absorption, which is spatially localized on the nanoparticle layer. We show that this enhanced light absorbance leads to ∼40-fold increases in the photon-to-electron conversion efficiency by the plasmonic nanostructures. We developed a model that successfully captures the essential physics of the plasmonic hot electron charge generation and separation in these structures. This model also allowed us to establish that efficient hot carrier extraction is limited to spectral regions where (i) the photons have energies higher than the Schottky junctions and (ii) the absorption of light is localized on the metal nanoparticles.

  18. Ultrathin microwave absorber based on metamaterial

    NASA Astrophysics Data System (ADS)

    Kim, Y. J.; Yoo, Y. J.; Hwang, J. S.; Lee, Y. P.

    2016-11-01

    We suggest that ultrathin broadband metamaterial is a perfect absorber in the microwave regime by utilizing the properties of a resistive sheet and metamaterial. Meta-atoms are composed of four-leaf clover-shape metallic patterns and a metal plane separated by three intermediate resistive sheet layers between four dielectric layers. We interpret the absorption mechanism of the broadband by using the distribution of surface currents at specific frequencies. The simulated absorption was over 99% in 1.8–4.2 GHz. The corresponding experimental absorption was also over 99% in 2.62–4.2 GHz; however, the absorption was slightly lower than 99% in 1.8–2.62 GHz because of the sheet resistance and the changed values for the dielectric constant. Furthermore, it is independent of incident angle. The results of this research indicate the possibility of applications, due to the suppression of noxious exposure, in cell phones, computers and microwave equipments.

  19. A variable passive low-frequency absorber

    NASA Astrophysics Data System (ADS)

    Larsen, Niels Werner; Thompson, Eric R.; Gade, Anders Christian

    2005-04-01

    Multi-purpose concert halls face a dilemma. They can host classical music concerts, rock concerts and spoken word performances in a matter of a short period. These different performance types require significantly different acoustic conditions in order to provide the best sound quality to both the performers and the audience. A recommended reverberation time for classical music may be in the range of 1.5-2 s for empty halls, where rock music sounds best with a reverberation time around 0.8-1 s. Modern rhythmic music often contains high levels of sound energy in the low frequency bands but still requires a high definition for good sound quality. Ideally, the absorption of the hall should be adjustable in all frequency bands in order to provide good sound quality for all types of performances. The mid and high frequency absorption is easily regulated, but adjusting the low-frequency absorption has typically been too expensive or requires too much space to be practical for multi-purpose halls. Measurements were made on a variable low-frequency absorber to develop a practical solution to the dilemma. The paper will present the results of the measurements as well as a possible design.

  20. Oil well sucker rod shock absorber

    SciTech Connect

    Knox, F.B.

    1986-02-18

    An oil well sucker rod shock absorber is described which consists of: an outer cylindrical casing defined by a cylindrical wall and having a removable upper plug and lower plug disposed respectively at upper and lower extremities of the casing. The upper plug has an axial bore and the lower plug defines a closed lower end and has an upwardly facing top surface. The plunger rod is connected to the sucker rod and is slidably disposed in the bore of the upper plug. A piston within the cylindrical casing is coupled to the plunger rod and has a downwardly facing bottom surface. Biasing means have a maximum vertical length disposed vertically within the casing and extending between the downwardly facing surface of the piston and the upwardly facing surface of the lower plug means at all times. This allows vertical reciprocal translation of the plunger rod and the piston within the cylindrical casing downwardly against the biasing means. Apertures are disposed through the cylindrical casing along the entire length thereof opposite the length of the biasing means, allowing downhole fluid pressure to be applied to the piston within the cylindrical casing via the apertures to be added to the force of the biasing means, without causing a fluid lock within the cylinder. Slap and wear of the sucker rod resulting therefrom are reduced and damage prevented.

  1. Spacesuit Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Hodgson, Ed; Izenso, Mike; Chan, Weibo; Cupples, Scott

    2011-01-01

    For decades advanced spacesuit developers have pursued a regenerable, robust non-venting system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's lithium chloride Heat Pump Radiator (HPR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. The SEAR is evacuated at the onset of operations and thereafter, the water vapor absorption rate of the HPR maintains a low pressure environment for the SWME to evaporate effectively. This water vapor captured by solid LiCl in the HPR with a high enthalpy of absorption, results in sufficient temperature lift to reject most of the heat to space by radiation. After the sortie, the HPR would be heated up in a regenerator to drive off and recover the absorbed evaporant. A one-fourth scale prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The HPR was able to stably reject 60 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

  2. Space Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Stephan, Ryan; Hodgson, Ed; Izenson, Mike; Chen, Weibo

    2012-01-01

    A system for non-venting thermal control for spacesuits was built by integrating two previously developed technologies, namely NASA s Spacesuit Water Membrane Evaporator (SWME), and Creare s flexible version of the Lithium Chloride Absorber Radiator (LCAR). This SEAR system was tested in relevant thermal vacuum conditions. These tests show that a 1 m2 radiator having about three times as much absorption media as in the test article would be required to support a 7 hour spacewalk. The serial flow arrangement of the LCAR of the flexible version proved to be inefficient for venting non-condensable gas (NCG). A different LCAR packaging arrangement was conceived wherein the Portable Life Support System (PLSS) housing would be made with a high-strength carbon fiber composite honeycomb, the cells of which would be filled with the chemical absorption media. This new packaging reduces the mass and volume impact of the SEAR on the Portable Life Support System (PLSS) compared to the flexible design. A 0.2 sq m panel with flight-like honeycomb geometry is being constructed and will be tested in thermal and thermal vacuum conditions. Design analyses forecast improved system performance and improved NCG control. A flight-like regeneration system also is also being built and tested. Design analyses for the structurally integrated prototype as well as the earlier test data show that SEAR is not only practical for spacesuits but also has useful applications in spacecraft thermal control.

  3. Multifunctional Space Evaporator-Absorber-Radiator (SEAR)

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Hodgson, Ed; Izenson, Mike; Chen, Weibo

    2013-01-01

    A system for non-venting thermal control for spacesuits was built by integrating two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's flexible version of the Lithium Chloride Absorber Radiator (LCAR). This SEAR system was tested in relevant thermal vacuum conditions. These tests show that a 1 sq m radiator having about three times as much absorption media as in the test article would be required to support a 7 hour spacewalk. The serial flow arrangement of the LCAR of the flexible version proved to be inefficient for venting non-condensable gas (NCG). A different LCAR packaging arrangement was conceived wherein the Portable Life Support System (PLSS) housing would be made with a high-strength carbon fiber composite honeycomb, the cells of which would be filled with the chemical absorption media. This new packaging reduce the mass and volume impact of the SEAR on the Portable Life Support System (PLSS) compared to the flexible design. A 0.2 sq m panel with flight-like honeycomb geometry is being constructed and will be tested in thermal and thermal vacuum conditions. Design analyses forecast improved system performance and improved NCG control. A flight-like regeneration system also is also being built and tested. Design analyses for the structurally integrated prototype as well as the earlier test data show that SEAR is not only practical for spacesuits but also has useful applications in spacecraft thermal control.

  4. Design of a multiband terahertz perfect absorber

    NASA Astrophysics Data System (ADS)

    Dan, Hu; Hong-yan, Wang; Zhen-jie, Tang; Xi-wei, Zhang; Lin, Ju; Hua-ying, Wang

    2016-03-01

    A thin-flexible multiband terahertz metamaterial absorber (MA) has been investigated. Each unit cell of the MA consists of a simple metal structure, which includes the top metal resonator ring and the bottom metallic ground plane, separated by a thin-flexible dielectric spacer. Finite-difference time domain simulation indicates that this MA can achieve over 99% absorption at frequencies of 1.50 THz, 3.33 THz, and 5.40 THz by properly assembling the sandwiched structure. However, because of its asymmetric structure, the MA is polarization-sensitive and can tune the absorptivity of the second absorption peak by changing the incident polarization angle. The effect of the error of the structural parameters on the absorption efficiency is also carefully analyzed in detail to guide the fabrication. Moreover, the proposed MA exhibits high refractive-index sensing sensitivity, which has potential applications in multi-wavelength sensing in the terahertz region. Project supported by the National Natural Science Foundation of China (Grant No. 11504006), the Key Scientific Research Project of Higher Education of Henan Province, China (Grant No. 15A140002), and the Science and Technology Planning Project of Henan Province, China (Grant No. 142300410366).

  5. Magnetorheological elastomers in tunable vibration absorbers

    NASA Astrophysics Data System (ADS)

    Ginder, John M.; Schlotter, William F.; Nichols, Mark E.

    2001-07-01

    Filling an elastomeric material with magnetizable particles leads to mechanical properties -shear moduli, tensile moduli, and magnetostriction coefficients - that are reversibly and rapidly controllable by an applied magnetic field. The origin of the field dependence of these properties is the existence of field-induced dipole magnetic forces between the particles. These 'smart' composites, which are sometimes termed magnetorheological (MR) elastomers, have been explored for use in a number of components, including automotive suspension bushings. In these and other applications, the tunability of the stiffness can enhance the compliance-control or vibration-transfer performance of the complex mechanical systems in which they are used. In the present study, we have constructed a simple one-degree-of-freedom mass-spring system - an adaptive tuned vibration absorber - that utilizes MR elastomers as variable-spring-rate elements. This device was used not only to explore the performance of such tunable components, but also to extend measurements of the shear moduli of these materials to higher frequencies than has previously been reported. We find that the field-induced increase in moduli of these materials is effective to mechanical frequencies well above 1 kHz, and that the moduli are consistent with the behavior expected for filled elastomers.

  6. Superconducting High Energy Resolution Gamma-ray Spectrometers

    SciTech Connect

    Chow, D T

    2002-02-22

    We have demonstrated that a bulk absorber coupled to a TES can serve as a good gamma-ray spectrometer. Our measured energy resolution of 70 eV at 60 keV is among the best measurements in this field. We have also shown excellent agreement between the noise predictions and measured noise. Despite this good result, we noted that our detector design has shortcomings with a low count rate and vulnerabilities with the linearity of energy response. We addressed these issues by implementation of an active negative feedback bias. We demonstrated the effects of active bias such as additional pulse shortening, reduction of TES change in temperature during a pulse, and linearization of energy response at low energy. Linearization at higher energy is possible with optimized heat capacities and thermal conductivities of the microcalorimeter. However, the current fabrication process has low control and repeatability over the thermal properties. Thus, optimization of the detector performance is difficult until the fabrication process is improved. Currently, several efforts are underway to better control the fabrication of our gamma-ray spectrometers. We are developing a full-wafer process to produce TES films. We are investigating the thermal conductivity and surface roughness of thicker SiN membranes. We are exploring alternative methods to couple the absorber to the TES film for reproducibility. We are also optimizing the thermal conductivities within the detector to minimize two-element phonon noise. We are experimenting with different absorber materials to optimize absorption efficiency and heat capacity. We are also working on minimizing Johnson noise from the E S shunt and SQUID amplifier noise. We have shown that our performance, noise, and active bias models agree very well with measured data from several microcalorimeters. Once the fabrication improvements have been implemented, we have no doubt that our gamma-ray spectrometer will achieve even more spectacular results.

  7. UNIDENTIFIED {gamma}-RAY SOURCES: HUNTING {gamma}-RAY BLAZARS

    SciTech Connect

    Massaro, F.; Ajello, M.; D'Abrusco, R.; Paggi, A.; Tosti, G.; Gasparrini, D.

    2012-06-10

    One of the main scientific objectives of the ongoing Fermi mission is unveiling the nature of unidentified {gamma}-ray sources (UGSs). Despite the major improvements of Fermi in the localization of {gamma}-ray sources with respect to the past {gamma}-ray missions, about one-third of the Fermi-detected objects are still not associated with low-energy counterparts. Recently, using the Wide-field Infrared Survey Explorer survey, we discovered that blazars, the rarest class of active galactic nuclei and the largest population of {gamma}-ray sources, can be recognized and separated from other extragalactic sources on the basis of their infrared (IR) colors. Based on this result, we designed an association method for the {gamma}-ray sources to recognize if there is a blazar candidate within the positional uncertainty region of a generic {gamma}-ray source. With this new IR diagnostic tool, we searched for {gamma}-ray blazar candidates associated with the UGS sample of the second Fermi {gamma}-ray LAT catalog (2FGL). We found that our method associates at least one {gamma}-ray blazar candidate as a counterpart to each of 156 out of 313 UGSs analyzed. These new low-energy candidates have the same IR properties as the blazars associated with {gamma}-ray sources in the 2FGL catalog.

  8. Unidentified Gamma-Ray Sources: Hunting Gamma-Ray Blazars

    SciTech Connect

    Massaro, F.; D'Abrusco, R.; Tosti, G.; Ajello, M.; Gasparrini, A.Paggi.D.

    2012-04-02

    One of the main scientific objectives of the ongoing Fermi mission is unveiling the nature of the unidentified {gamma}-ray sources (UGSs). Despite the large improvements of Fermi in the localization of {gamma}-ray sources with respect to the past {gamma}-ray missions, about one third of the Fermi-detected objects are still not associated to low energy counterparts. Recently, using the Wide-field Infrared Survey Explorer (WISE) survey, we discovered that blazars, the rarest class of Active Galactic Nuclei and the largest population of {gamma}-ray sources, can be recognized and separated from other extragalactic sources on the basis of their infrared (IR) colors. Based on this result, we designed an association method for the {gamma}-ray sources to recognize if there is a blazar candidate within the positional uncertainty region of a generic {gamma}-ray source. With this new IR diagnostic tool, we searched for {gamma}-ray blazar candidates associated to the UGS sample of the second Fermi {gamma}-ray catalog (2FGL). We found that our method associates at least one {gamma}-ray blazar candidate as a counterpart each of 156 out of 313 UGSs analyzed. These new low-energy candidates have the same IR properties as the blazars associated to {gamma}-ray sources in the 2FGL catalog.

  9. Development of Magnetic Microcalorimeters for Gamma-Ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Le, L. N.; Hummatov, R.; Hall, J. A.; Cantor, R. C.; Boyd, S. T. P.

    2016-07-01

    Integrating the SQUIDs and sensing coils of magnetic microcalorimeters onto the same die is a promising approach for maximizing flux coupling and signal/noise. However, new challenges in microfabrication must be overcome, because the underlying SQUID devices are sensitive to chemical attack and elevated processing temperatures. In this report, we describe development and details of a microfabrication process for integrated SQUID/sensor gamma-ray magnetic microcalorimeters with electroformed gold absorbers, starting from a modified version of the STAR Cryoelectronics "Delta 1000" Josephson Junction process.

  10. Ceramic Matrix Composites Performances Under High Gamma Radiation Doses

    NASA Astrophysics Data System (ADS)

    Cemmi, A.; Baccaro, S.; Fiore, S.; Gislon, P.; Serra, E.; Fassina, S.; Ferrari, E.; Ghisolfi, E.

    2014-06-01

    Ceramic matrix composites reinforced by continuous ceramic fibers (CMCs) represent a class of advanced materials developed for applications in automotive, aerospace, nuclear fusion reactors and in other specific systems for harsh environments. In the present work, the silicon carbide/silicon carbide (SiCf/SiC) composites, manufactured by Chemical Vapour Infiltration process at FN S.p.A. plant, have been evaluated in term of gamma radiation hardness at three different absorbed doses (up to around 3MGy). Samples behavior has been investigated before and after irradiation by means of mechanical tests (flexural strength) and by surface and structural analyses (X-ray diffraction, SEM, FTIR-ATR, EPR).

  11. Finnish spectrolite as high-dose gamma detector

    NASA Astrophysics Data System (ADS)

    Antonio, Patrícia L.; Caldas, Linda V. E.

    2015-11-01

    A natural material called spectrolite, from Finland, was studied in this work. The purpose was to test it in gamma radiation beams to verify its performance as a high-dose detector. From this material, pellets were manufactured with two different concentrations of Teflon and spectrolite, and their responses were verified using two luminescent techniques: thermoluminescence (TL) and optically stimulated luminescence (OSL). The TL and OSL signals were evaluated by means of characterization tests of the material response, after exposure to a nominal absorbed dose interval of 5 Gy to 10 kGy. The results obtained, for both concentrations, showed a good performance of this material in beams of high-dose gamma radiation. Both techniques were utilized in order to investigate the properties of the spectrolite+Teflon samples for different applications.

  12. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1994-01-01

    The Burst and Transient Source Experiment (BATSE) is one of four instruments on the Compton observatory which was launched by the space shuttle Atlantis on April 5, 1991. As of mid-March, 1994, BATSE detected more than 925 cosmic gamma-ray bursts and more than 725 solar flares. Pulsed gamma rays have been detected from at least 16 sources and emission from at least 28 sources (including most of the pulsed sources) has been detected by the earth occultation technique. UAH participation in BATSE is extensive but can be divided into two main areas, operations and data analysis. The daily BATSE operations tasks represent a substantial level of effort and involve a large team composed of MSFC personnel as well as contractors such as UAH. The scientific data reduction and analysis of BATSE data is also a substantial level of effort in which UAH personnel have made significant contributions.

  13. Calculation of absorbed doses to water pools in severe accident sequences

    SciTech Connect

    Weber, C.F.

    1991-12-01

    A methodology is presented for calculating the radiation dose to a water pool from the decay of uniformly distributed nuclides in that pool. Motivated by the need to accurately model radiolysis reactions of iodine, direct application is made to fission product sources dissolved or suspended in containment sumps or pools during a severe nuclear reactor accident. Two methods of calculating gamma absorption are discussed - one based on point-kernal integration and the other based on Monte Carlo techniques. Using least-squares minimization, the computed results are used to obtain a correlation that relates absorbed dose to source energy and surface-to-volume ratio of the pool. This correlation is applied to most relevant fission product nuclides and used to actually calculate transient sump dose rate in a pressurized-water reactor (PWR) severe accident sequence.

  14. Gamma radiation shielding and health physics characteristics of diaspore-flyash concretes.

    PubMed

    Singh, Kanwaldeep; Singh, Sukhpal; Singh, S P; Mudahar, Gurmel S; Dhaliwal, A S

    2015-06-01

    Different gamma radiation interaction parameters has been measured experimentally for the prepared diaspore-flyash concretes at 59.54, 662, 1173 and 1332 keV using narrow-beam transmission geometry and results are found to be in good agreement with theoretical values computed with a computer programme, WinXCom. The radiation exposure rate and absorbed dose rate for the gamma radiation with and without shielding of diaspore-flyash concretes have been determined using linear attenuation results. The results show that on average, there is reduction of 95%, 53% and 40% in dose rate for gamma sources (241)Am, (137)Cs and (60)Co, respectively with diaspore-flyash concretes as shielding material. Other health physics parameters namely equivalent dose, effective dose, gamma flux and energy fluence rate have also been determined.

  15. Gamma-Ray Spectrometers Using Superconducting Transition Edge Sensors with External Active Feedback Bias

    SciTech Connect

    Chow, D.T.; van den Berg, M.L.; Loshak, A.; Frank, M.; Barbee, T.W.; Labov, S.E.

    2000-09-22

    The authors are developing x-ray and gamma-ray spectrometers with high absorption efficiency and high energy-resolution for x-ray and gamma-ray spectroscopy. They are microcalorimeters consisting of a bulk Sn absorber coupled to a Mo/Cu multilayer superconducting transition edge sensor (TES). The authors have measured an energy resolution of 70 eV FWHM for 60 keV incident gamma-rays using electrothermal feedback. They have also operated these microcalorimeters with an external active feedback bias to linearize the detector response, improve the count rate performance, and extend the detection energy range. They present x-ray and gamma-ray results operation of this detector design in both bias modes.

  16. Improvement of colour strength and colourfastness properties of gamma irradiated cotton using reactive black-5

    NASA Astrophysics Data System (ADS)

    Ahmad Bhatti, Ijaz; Adeel, Shahid; Nadeem, Raziya; Asghar, Toheed

    2012-03-01

    The dyeing behaviour of gamma irradiated cotton fabric using Reactive Black-5 dye powder has been investigated. The mercerized, bleached and plain weaved cotton fabric was irradiated to different absorbed doses of 100, 200, 300, 400, 500 and 600 Gy using Co-60 gamma irradiator. Dyeing was performed using irradiated and un-irradiated cotton with dye solutions. The dyeing parameters such as temperature of dyeing, time of dyeing and pH of dyeing solutions were optimised. The colour strength values of dyed fabrics were evaluated by comparing irradiated and un-irradiated cotton in CIE Lab system using Spectra flash SF650. Methods suggested by International Standard Organisation (ISO) were employed to study the effect of gamma irradiation on the colourfastness properties of dyed fabric. It is found that gamma irradiated cotton dyed with Reactive Black-5 has not only improved the colour strength but also enhanced the rating of fastness properties.

  17. Gamma ray collimator

    NASA Technical Reports Server (NTRS)

    Casanova, Edgar J. (Inventor)

    1991-01-01

    A gamma ray collimator including a housing having first and second sections is disclosed. The first section encloses a first section of depleted uranium which is disposed for receiving and supporting a radiation emitting component such as cobalt 60. The second section encloses a depleted uranium member which is provided with a conical cut out focusing portion disposed in communication with the radiation emitting element for focusing the emitted radiation to the target.

  18. Radionuclide concentrations in soil and lifetime cancer risk due to gamma radioactivity in Kirklareli, Turkey.

    PubMed

    Taskin, H; Karavus, M; Ay, P; Topuzoglu, A; Hidiroglu, S; Karahan, G

    2009-01-01

    The objective of this study is to evaluate and map soil radionuclides' activity concentrations and environmental outdoor gamma dose rates (terrestrial and cosmic) in Kirklareli, Turkey. The excess lifetime cancer risks are also calculated. Outdoor gamma dose rates were determined in 230 sampling stations and soil samples were taken from 177 locations. The coordinates of the readings were determined by the Global Positioning System (GPS). The outdoor gamma dose rates were determined by Eberline smart portable device (ESP-2) and measurements were taken in air for two minutes at 1m from the ground. The average outdoor gamma dose rate was 118+/-34nGyh(-1). Annual effective gamma dose of Kirklareli was 144microSv and the excess lifetime cancer risk of 5.0x10(-4). Soil samples were analyzed by gamma spectroscopy. The average 226Ra, 238U, 232Th, 137Cs, and 40K activities were 37+/-18Bqkg(-1), 28+/-13Bqkg(-1), 40+/-18Bqkg(-1), 8+/-5Bqkg(-1) and 667+/-281Bqkg(-1), respectively. The average soil radionuclides' concentrations of Kirklareli were within the worldwide range although some extreme values had been determined. Annual effective gamma doses and the excess lifetime risks of cancer were higher than the world's average. PMID:19038480

  19. Towards absorbing outer boundaries in general relativity

    NASA Astrophysics Data System (ADS)

    Buchman, Luisa T.; Sarbach, Olivier C. A.

    2006-12-01

    We construct exact solutions to the Bianchi equations on a flat spacetime background. When the constraints are satisfied, these solutions represent in- and outgoing linearized gravitational radiation. We then consider the Bianchi equations on a subset of flat spacetime of the form [0, T] × BR, where BR is a ball of radius R, and analyse different kinds of boundary conditions on ∂BR. Our main results are as follows. (i) We give an explicit analytic example showing that boundary conditions obtained from freezing the incoming characteristic fields to their initial values are not compatible with the constraints. (ii) With the help of the exact solutions constructed, we determine the amount of artificial reflection of gravitational radiation from constraint-preserving boundary conditions which freeze the Weyl scalar Ψ0 to its initial value. For monochromatic radiation with wave number k and arbitrary angular momentum number ell >= 2, the amount of reflection decays as (kR)-4 for large kR. (iii) For each L >= 2, we construct new local constraint-preserving boundary conditions which perfectly absorb linearized radiation with ell <= L. (iv) We generalize our analysis to a weakly curved background of mass M and compute first-order corrections in M/R to the reflection coefficients for quadrupolar odd-parity radiation. For our new boundary condition with L = 2, the reflection coefficient is smaller than that for the freezing Ψ0 boundary condition by a factor of M/R for kR > 1.04. Implications of these results for numerical simulations of binary black holes on finite domains are discussed.

  20. Optical Sensors for Monitoring Gamma and Neutron Radiation

    NASA Technical Reports Server (NTRS)

    Boyd, Clark D.

    2011-01-01

    For safety and efficiency, nuclear reactors must be carefully monitored to provide feedback that enables the fission rate to be held at a constant target level via adjustments in the position of neutron-absorbing rods and moderating coolant flow rates. For automated reactor control, the monitoring system should provide calibrated analog or digital output. The sensors must survive and produce reliable output with minimal drift for at least one to two years, for replacement only during refueling. Small sensor size is preferred to enable more sensors to be placed in the core for more detailed characterization of the local fission rate and fuel consumption, since local deviations from the norm tend to amplify themselves. Currently, reactors are monitored by local power range meters (LPRMs) based on the neutron flux or gamma thermometers based on the gamma flux. LPRMs tend to be bulky, while gamma thermometers are subject to unwanted drift. Both electronic reactor sensors are plagued by electrical noise induced by ionizing radiation near the reactor core. A fiber optic sensor system was developed that is capable of tracking thermal neutron fluence and gamma flux in order to monitor nuclear reactor fission rates. The system provides near-real-time feedback from small- profile probes that are not sensitive to electromagnetic noise. The key novel feature is the practical design of fiber optic radiation sensors. The use of an actinoid element to monitor neutron flux in fiber optic EFPI (extrinsic Fabry-Perot interferometric) sensors is a new use of material. The materials and structure used in the sensor construction can be adjusted to result in a sensor that is sensitive to just thermal, gamma, or neutron stimulus, or any combination of the three. The tested design showed low sensitivity to thermal and gamma stimuli and high sensitivity to neutrons, with a fast response time.

  1. Nylon shock absorber prevents injury to parachute jumpers

    NASA Technical Reports Server (NTRS)

    Mandel, J. A.

    1966-01-01

    Nylon shock absorbers reduce the canopy-opening shock of a parachute to a level that protects the wearer from injury. A shock absorber is mounted on each of the four risers between the shroud lines and the harness. Because of their size and location, they pose no problem in repacking the chute and harness after a jump.

  2. An Absorbing Look at Terry-Cloth Towels

    ERIC Educational Resources Information Center

    Moyer, Richard; Everett, Susan

    2010-01-01

    This article describes a lesson where students explore the absorbency of several towels with different weaves and weights. The lesson follows the 5E learning-cycle model and incorporates engineering in the sense of product testing with a focus on the relationship between the weave of a towel and its absorbency. The National Science Education…

  3. 14 CFR 27.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Tires and shock absorbers. 27.475 Section... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and shock... be in their static position and the shock absorbers to be in their most critical position....

  4. 14 CFR 27.475 - Tires and shock absorbers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Tires and shock absorbers. 27.475 Section... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and shock... be in their static position and the shock absorbers to be in their most critical position....

  5. Science on a Roll. Part One: Absorbing Inquiry.

    ERIC Educational Resources Information Center

    Brendzel, Sharon

    2002-01-01

    Presents an activity that tests the absorbency of different brands of paper towels. Suggests making this activity into an open-ended inquiry type of activity. Includes sample questions to guide students, topics for class discussion, and sample methods of using the absorbency activity. (KHR)

  6. 21 CFR 880.5300 - Medical absorbent fiber.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... and that is used for applying medication to, or absorbing small amounts of body fluids from, a patient's body surface. Absorbent fibers intended solely for cosmetic purposes are not included in...

  7. Physically absorbable reagents-collectors in elementary flotation

    SciTech Connect

    S.A. Kondrat'ev; I.G. Bochkarev

    2007-09-15

    Based on the reviewed researches held at the Institute of Mining, Siberian Branch, Russian Academy of Sciences, the effect of physically absorbable reagents-collectors on formation of a flotation complex and its stability in turbulent pulp flows in flotation machines of basic types is considered. The basic requirements for physically absorbable reagents-collectors at different flotation stages are established.

  8. Shielding property of natural biomass against gamma rays.

    PubMed

    Mavi, B; Gurbuz, L F; Ciftci, H; Akkurt, I

    2014-01-01

    Algae and cyanobacteria are capable living under harsh conditions in the natural environments and can develop peculiar survival processes. In order to evaluate radiation shielding properties of green algae; Chlorella vulgaris, Scenedesmus obliquus, and cyanobacteria; Synechococcus sp., Planktothrix limnetica, Microcystis aeruginosa, Arthrospira maxima, Anabaena affinis, Phormidium articulatum, and Pseudoanabaena sp. were cultured in batch systems. Air dried biomass was tested for its high tolerance to gamma-radiations in terms of linear attenuation coefficients. In the present work, the linear and mass attenuation coefficients were measured at photon energies of 1173 and 1332 keV. Protection capacity of some biomass was observed to be higher than a 1-cm thick lead standard for comparison. Gamma ray related protection depends not only to thickness but also to density (g/cm3). Hence the effect of biomass density also was tested and significantly found the tested biomass absorbed more of the incoming energy on a density basis than lead. This paper discusses the a new approach to environmental protection from gamma ray. The findings suggest that the test samples, especially cyanobacteria, have a potential for reducing gamma ray more significantly than lead and can be used as shielding materials.

  9. Experimental simulation of A-bomb gamma ray spectra: revisited.

    PubMed

    Pattison, John E; Payne, Lester C; Hugtenburg, Richard P; Beddoe, Alun H; Charles, Monty W

    2004-01-01

    It has been reported recently that the A-bomb gamma ray spectra received by the colon of the average Japanese survivor of Hiroshima and Nagasaki may be experimentally simulated using a hospital-based Philips SL15 linear accelerator. The simulated A-bomb gamma radiation may be used in radiobiology experiments to determine, amongst other things, the biological effectiveness of the A-bomb gamma radiation. However, in that study, the electron beams from the linear accelerator were poorly defined and photon contamination was ignored. In the study reported here, a Varian Clinac 2100C linear accelerator has been used for the same purpose but with photon contamination included in better defined output electron beams. It is found that the A-bomb gamma radiation can still be matched to an acceptable degree (<10%). The cause of the slightly poorer fit was due mainly to the different ranges of energies available from the linear accelerators used. The absorbed dose received by model breasts was also estimated in this study for the same situations as in the previous study. The ratio of the breast to colon doses was found to be only (3.9 +/- 4.0)% low compared with the expected values of 1.17 and 1.16 for Hiroshima and Nagasaki, respectively. These results provide further confirmation of the acceptability of the simple cylindrically symmetrical body models employed in these studies to represent the average Japanese survivor.

  10. Shielding property of natural biomass against gamma rays.

    PubMed

    Mavi, B; Gurbuz, L F; Ciftci, H; Akkurt, I

    2014-01-01

    Algae and cyanobacteria are capable living under harsh conditions in the natural environments and can develop peculiar survival processes. In order to evaluate radiation shielding properties of green algae; Chlorella vulgaris, Scenedesmus obliquus, and cyanobacteria; Synechococcus sp., Planktothrix limnetica, Microcystis aeruginosa, Arthrospira maxima, Anabaena affinis, Phormidium articulatum, and Pseudoanabaena sp. were cultured in batch systems. Air dried biomass was tested for its high tolerance to gamma-radiations in terms of linear attenuation coefficients. In the present work, the linear and mass attenuation coefficients were measured at photon energies of 1173 and 1332 keV. Protection capacity of some biomass was observed to be higher than a 1-cm thick lead standard for comparison. Gamma ray related protection depends not only to thickness but also to density (g/cm3). Hence the effect of biomass density also was tested and significantly found the tested biomass absorbed more of the incoming energy on a density basis than lead. This paper discusses the a new approach to environmental protection from gamma ray. The findings suggest that the test samples, especially cyanobacteria, have a potential for reducing gamma ray more significantly than lead and can be used as shielding materials. PMID:24912221

  11. Effects of Cosmic Infrared Background on High Energy Delayed Gamma-Rays From Gamma-Ray Bursts

    SciTech Connect

    Murase, Kohta; Asano, Katsuaki; Nagataki, Shigehiro; /Kyoto U., Yukawa Inst., Kyoto /KIPAC, Menlo Park

    2007-04-06

    Regenerated high energy emissions from gamma-ray bursts (GRBs) are studied in detail. If the primary emission spectrum extends to TeV range, these very high energy photons will be absorbed by the cosmic infrared background (CIB). The created high energy electron-positron pairs up-scatter not only cosmic microwave background (CMB) photons but also CIB photons, and secondary photons are generated in the GeV-TeV range. These secondary delayed photons may be observed in the near future, and useful for a consistency check for the primary spectra and GRB physical parameters. The up-scattered CIB photons cannot be neglected for low redshift bursts and/or GRBs with a relatively low maximum photon energy. The secondary gamma-rays also give us additional information on the CIB, which is uncertain in observations so far.

  12. Gamma-Ray Localization of Terrestrial Gamma-Ray Flashes

    SciTech Connect

    Marisaldi, M.; Labanti, C.; Fuschino, F.; Bulgarelli, A.; Trifoglio, M.; Di Cocco, G.; Gianotti, F.; Argan, A.; De Paris, G.; Trois, A.; Del Monte, E.; Costa, E.; Di Persio, G.; Donnarumma, I.; Evangelista, Y.; Feroci, M.; Lazzarotto, F.; Pacciani, L.; Rubini, A.; Sabatini, S.

    2010-09-17

    Terrestrial gamma-ray flashes (TGFs) are very short bursts of high-energy photons and electrons originating in Earth's atmosphere. We present here a localization study of TGFs carried out at gamma-ray energies above 20 MeV based on an innovative event selection method. We use the AGILE satellite Silicon Tracker data that for the first time have been correlated with TGFs detected by the AGILE Mini-Calorimeter. We detect 8 TGFs with gamma-ray photons of energies above 20 MeV localized by the AGILE gamma-ray imager with an accuracy of {approx}5-10 deg. at 50 MeV. Remarkably, all TGF-associated gamma rays are compatible with a terrestrial production site closer to the subsatellite point than 400 km. Considering that our gamma rays reach the AGILE satellite at 540 km altitude with limited scattering or attenuation, our measurements provide the first precise direct localization of TGFs from space.

  13. Broadband terahertz metamaterial absorber based on sectional asymmetric structures.

    PubMed

    Gong, Cheng; Zhan, Mingzhou; Yang, Jing; Wang, Zhigang; Liu, Haitao; Zhao, Yuejin; Liu, Weiwei

    2016-01-01

    We suggest and demonstrate the concept and design of sectional asymmetric structures which can manipulate the metamaterial absorber's working bandwidth with maintaining the other inherent advantages. As an example, a broadband terahertz perfect absorber is designed to confirm its effectiveness. The absorber's each cell integrates four sectional asymmetric rings, and the entire structure composed of Au and Si3N4 is only 1.9 μm thick. The simulation results show the bandwidth with absorptivity being larger than 90% is extended by about 2.8 times comparing with the conventional square ring absorber. The composable small cell, ultra-thin, and broadband absorption with polarization and incident angle insensitivity will make the absorber suitable for the applications of focal plane array terahertz imaging. PMID:27571941

  14. Performance evaluation of CFRP-rubber shock absorbers

    SciTech Connect

    Lamanna, Giuseppe Sepe, Raffaele

    2014-05-15

    In the present work a numerical investigation on the energy absorbing capability of dedicated structural components made of a carbon fiber reinforced polymer and an emulsion polymerised styrene butadiene rubber is reported. The shock absorbers are devices designed to absorb large amounts of energy by sacrificing their own structural integrity. Their aim is to cushion the effects of an impact phenomenon with the intent to preserve other structures from global failure or local damaging. Another important role of shock absorbers is reducing the peak of the acceleration showed during an impact phenomenon. This effect is of considerable interest in the case of vehicles to preserve passengers’ safety. Static and dynamic numerical results are compared with experimental ones in terms of mean crushing forces, energy and peak crushing. The global performance of the absorbers has been evaluated by referencing to a proposed quality index.

  15. Metamaterial perfect absorber using the magnetic resonance of dielectric inclusions

    NASA Astrophysics Data System (ADS)

    Dung, Nguyen Van; Tung, Bui Son; Khuyen, Bui Xuan; Yoo, Young Joon; Lee, YoungPak; Rhee, Joo Yull; Lam, Vu Dinh

    2016-04-01

    In this report, we introduce a stable metamaterial perfect absorber at GHz frequency based on a novel design of a Mie-type resonance. A single perfect absorption peak is achieved at 9.54 GHz, and the influence of the structural parameters on the absorption behavior is studied; the results were consistent with dielectric-resonator theory. The absorption is demonstrated to be polarizationinsensitive; furthermore, the absorber structure can work for a wide incident angle without any change in the resonance peak. Our absorber structure can also control 47% of the resonance peak's position by changing the temperature of the dielectric layer. Our absorber structure can also be applied as an electromagnetic-wave absorber for wide-incident-angle, thermally-controllable devices.

  16. Theory of patch-antenna metamaterial perfect absorbers

    NASA Astrophysics Data System (ADS)

    Bowen, Patrick T.; Baron, Alexandre; Smith, David R.

    2016-06-01

    A metasurface that absorbs waves from all directions of incidence can be achieved if the surface impedance is made to vary as a function of incidence angle in a specific manner. Here we show that a periodic array of planar nanoparticles coupled to a metal film can act as an absorbing metasurface with an angle-dependent impedance. Through a semi-analytical calculation based on coupled-mode theory, we find the perfect absorbing condition is equivalent to balancing the Ohmic and radiative losses of the nanoparticles at normal incidence. Absorption over a wide range of incidence angles can then be obtained by tailoring the scattered far-field pattern of the individual planar nanoparticles such that their radiative losses remain constant. The theory provides a means of understanding the behavior of perfect absorbing structures that have been observed experimentally or numerically, reconciling previously published theories and enabling the optimization of absorbing surfaces.

  17. Thermally induced nonlinear optical absorption in metamaterial perfect absorbers

    SciTech Connect

    Guddala, Sriram Kumar, Raghwendra; Ramakrishna, S. Anantha

    2015-03-16

    A metamaterial perfect absorber consisting of a tri-layer (Al/ZnS/Al) metal-dielectric-metal system with top aluminium nano-disks was fabricated by laser-interference lithography and lift-off processing. The metamaterial absorber had peak resonant absorbance at 1090 nm and showed nonlinear absorption for 600ps laser pulses at 1064 nm wavelength. A nonlinear saturation of reflectance was measured to be dependent on the average laser power incident and not the peak laser intensity. The nonlinear behaviour is shown to arise from the heating due to the absorbed radiation and photo-thermal changes in the dielectric properties of aluminium. The metamaterial absorber is seen to be damage resistant at large laser intensities of 25 MW/cm{sup 2}.

  18. Performance evaluation of CFRP-rubber shock absorbers

    NASA Astrophysics Data System (ADS)

    Lamanna, Giuseppe; Sepe, Raffaele

    2014-05-01

    In the present work a numerical investigation on the energy absorbing capability of dedicated structural components made of a carbon fiber reinforced polymer and an emulsion polymerised styrene butadiene rubber is reported. The shock absorbers are devices designed to absorb large amounts of energy by sacrificing their own structural integrity. Their aim is to cushion the effects of an impact phenomenon with the intent to preserve other structures from global failure or local damaging. Another important role of shock absorbers is reducing the peak of the acceleration showed during an impact phenomenon. This effect is of considerable interest in the case of vehicles to preserve passengers' safety. Static and dynamic numerical results are compared with experimental ones in terms of mean crushing forces, energy and peak crushing. The global performance of the absorbers has been evaluated by referencing to a proposed quality index.

  19. Thermally induced nonlinear optical absorption in metamaterial perfect absorbers

    NASA Astrophysics Data System (ADS)

    Guddala, Sriram; Kumar, Raghwendra; Ramakrishna, S. Anantha

    2015-03-01

    A metamaterial perfect absorber consisting of a tri-layer (Al/ZnS/Al) metal-dielectric-metal system with top aluminium nano-disks was fabricated by laser-interference lithography and lift-off processing. The metamaterial absorber had peak resonant absorbance at 1090 nm and showed nonlinear absorption for 600ps laser pulses at 1064 nm wavelength. A nonlinear saturation of reflectance was measured to be dependent on the average laser power incident and not the peak laser intensity. The nonlinear behaviour is shown to arise from the heating due to the absorbed radiation and photo-thermal changes in the dielectric properties of aluminium. The metamaterial absorber is seen to be damage resistant at large laser intensities of 25 MW/cm2.

  20. AN IMAGING AND SPECTROSCOPIC STUDY OF FOUR STRONG Mg II ABSORBERS REVEALED BY GRB 060418

    SciTech Connect

    Pollack, L. K.; Prochaska, J. X.; Chen, H.-W.; Bloom, J. S.

    2009-08-20

    We present results from an imaging and spectroscopic study of four strong Mg II absorbers of W(2796) {approx}> 1 A revealed by the afterglow of GRB 060418 at z{sub GRB} = 1.491. These absorbers, at z = 0.603, 0.656, 1.107, and z {sub GRB}, exhibit large ion abundances that suggest neutral gas columns characteristic of damped Ly{alpha} systems. The imaging data include optical images obtained using Low-Resolution Imaging Spectrometer (LRIS) on the Keck I telescope and using Advanced Camera for Surveys on board Hubble Space Telescope, and near-infrared H-band images obtained using Persson's Auxiliary Nasmyth Infrared Camera on the Magellan Baade Telescope and K'-band images obtained using NIRC2 with laser guide star adaptive optics on the Keck II telescope. These images reveal six distinct objects at {delta} {theta} {approx}< 3.''5 of the afterglow's position, two of which exhibit well-resolved mature disk morphology, one shows red colors, and three are blue compact sources. Follow-up spectroscopic observations using LRIS confirm that one of the disk galaxies coincides with the Mg II absorber at z = 0.656. The observed broadband spectral energy distributions of the second disk galaxy and the red source indicate that they are associated with the absorbers at z = 0.603 and z = 1.107, respectively. These results show that strong Mg II absorbers identified in gamma-ray burst (GRB) afterglow spectra are associated with typical galaxies of luminosity {approx}0.1 - 1 L{sub *} at impact parameter of {rho} {approx}< 10 h {sup -1} kpc. The close angular separation would preclude easy detections toward a bright quasar. Finally, we associate the remaining three blue compact sources with the GRB host galaxy, noting that they are likely star-forming knots located at projected distances of {rho} = 2 - 12 h {sup -1} kpc from the afterglow. At the afterglow's position, we derive a 2{sigma} upper limit to the underlying star-formation rate intensity of 0.0074 M{sub sun} yr{sup -1} kpc

  1. ABSORBING WIPP BRINES: A TRU WASTE DISPOSAL STRATEGY

    SciTech Connect

    Yeamans, D. R.; Wrights, R. S.

    2002-02-25

    Los Alamos National Laboratory (LANL) has completed experiments involving 15 each, 250- liter experimental test containers of transuranic (TRU) heterogeneous waste immersed in two types of brine similar to those found in the underground portion of the Waste Isolation Pilot Plant (WIPP). To dispose of the waste without removing the brine from the test containers, LANL added commercially available cross-linked polyacrylate granules to absorb the 190 liters of brine in each container, making the waste compliant for shipping to the WIPP in a Standard Waste Box (SWB). Prior to performing the absorption, LANL and the manufacturer of the absorbent conducted laboratory and field tests to determine the ratio of absorbent to brine that would fully absorb the liquid. Bench scale tests indicated a ratio of 10 parts Castile brine to one part absorbent and 6.25 parts Brine A to one part absorbent. The minimum ratio of absorbent to brine was sought because headspace in the containers was limited. However, full scale testing revealed that the ratio should be adjusted to be about 15% richer in absorbent. Additional testing showed that the absorbent would not apply more than 13.8 kPa pressure on the walls of the vessel and that the absorbent would still function normally at that pressure and would not degrade in the approximately 5e-4 Sv/hr radioactive field produced by the waste. Heat generation from the absorption was minimal. The in situ absorption created a single waste stream of 8 SWBs whereas the least complicated alternate method of disposal would have yielded at least an additional 2600 liters of mixed low level liquid waste plus about two cubic meters of mixed low level solid waste, and would have resulted in higher risk of radiation exposure to workers. The in situ absorption saved $311k in a combination of waste treatment, disposal, material and personnel costs compared to the least expensive alternative and $984k compared to the original plan.

  2. Absorbing WIPP brines : a TRU waste disposal strategy.

    SciTech Connect

    Yeamans, D. R.; Wright, R.

    2002-01-01

    Los Alamos National Laboratory (LANL) has completed experiments involving 15 each, 250-liter experimental test containers of transuranic (TRU) heterogeneous waste immersed in two types of brine similar to those found in the underground portion of the Waste Isolation Pilot Plant (WIPP). To dispose of the waste without removing the brine from the test containers, LANL added commercially available cross-linked polyacrylate granules to absorb the 190 liters of brine in each container, making the waste compliant for shipping to the WlPP in a Standard Waste Box (SWB). Prior to performing the absorption, LANL and the manufacturer of the absorbent conducted laboratory and field tests to determine the ratio of absorbent to brine that would fully absorb the liquid. Bench scale tests indicated a ratio of 10 parts Castile brine to one part absorbent and 6.25 parts Brine A to one part absorbent. The minimum ratio of absorbent to brine was sought because headspace in the containers was limited. However, full scale testing revealed that the ratio should be adjusted to be about 15% richer in absorbent. Additional testing showed that the absorbent would not apply more than 13.8 kPa pressure on the walls of the vessel and that the absorbent would still function normally at that pressure and would not degrade in the approximately 5e-4 Sv/hr radioactive field produced by the waste. Heat generation from the absorption was minimal. The in situ absorption created a single waste stream of 8 SWBs whereas the least complicated alternate method of disposal would have yielded at least an additional 2600 liters of mixed low level liquid waste plus about two cubic meters of mixed low level solid waste, and would have resulted in higher risk of radiation exposure to workers. The in situ absorption saved $3 1 lk in a combination of waste treatment, disposal, material and personnel costs compared to the least expensive alternative and $984k compared to the original plan.

  3. Derivation of a Levelized Cost of Coating (LCOC) metric for evaluation of solar selective absorber materials

    SciTech Connect

    Ho, C. K.; Pacheco, J. E.

    2015-06-05

    A new metric, the Levelized Cost of Coating (LCOC), is derived in this paper to evaluate and compare alternative solar selective absorber coatings against a baseline coating (Pyromark 2500). In contrast to previous metrics that focused only on the optical performance of the coating, the LCOC includes costs, durability, and optical performance for more comprehensive comparisons among candidate materials. The LCOC is defined as the annualized marginal cost of the coating to produce a baseline annual thermal energy production. Costs include the cost of materials and labor for initial application and reapplication of the coating, as well as the cost of additional or fewer heliostats to yield the same annual thermal energy production as the baseline coating. Results show that important factors impacting the LCOC include the initial solar absorptance, thermal emittance, reapplication interval, degradation rate, reapplication cost, and downtime during reapplication. The LCOC can also be used to determine the optimal reapplication interval to minimize the levelized cost of energy production. As a result, similar methods can be applied more generally to determine the levelized cost of component for other applications and systems.

  4. Derivation of a Levelized Cost of Coating (LCOC) metric for evaluation of solar selective absorber materials

    DOE PAGES

    Ho, C. K.; Pacheco, J. E.

    2015-06-05

    A new metric, the Levelized Cost of Coating (LCOC), is derived in this paper to evaluate and compare alternative solar selective absorber coatings against a baseline coating (Pyromark 2500). In contrast to previous metrics that focused only on the optical performance of the coating, the LCOC includes costs, durability, and optical performance for more comprehensive comparisons among candidate materials. The LCOC is defined as the annualized marginal cost of the coating to produce a baseline annual thermal energy production. Costs include the cost of materials and labor for initial application and reapplication of the coating, as well as the costmore » of additional or fewer heliostats to yield the same annual thermal energy production as the baseline coating. Results show that important factors impacting the LCOC include the initial solar absorptance, thermal emittance, reapplication interval, degradation rate, reapplication cost, and downtime during reapplication. The LCOC can also be used to determine the optimal reapplication interval to minimize the levelized cost of energy production. As a result, similar methods can be applied more generally to determine the levelized cost of component for other applications and systems.« less

  5. Measurement of. gamma gamma. psi final states in psi' decay

    SciTech Connect

    Himel, T.M.; Abrams, G.S.; Alam, M.S.; Blocker, C.A.; Boyarski, A.M.; Breidenbach, M.; Burke, D.L.; Carithers, W.C.; Chinowsky, W.; Coles, M.W.; Cooper, S.; Dieterle, W.E.; Dillon, J.B.; Dorenbosch, J.; Dorfan, J.M.; Eaton, M.W.; Feldman, G.J.; Franklin, M.E.B.; Gidal, G.; Goldhaber, G.; Hanson, G.; Hayes, K.G.; Hitlin, D.G.; Hollebeek, R.J.; Innes, W.R.; Jaros, J.A.; Jenni, P.; Johnson, A.D.; Kadyk, J.A.; Lankford, A.J.; Larsen, R.R.; Levi, M.E.; Lueth, V.; Millikan, R.E.; Nelson, M.E.; Pang, C.Y.; Patrick, J.F.; Perl, M.L.; Richter, B.; Roussarie, A.; Scharre, D.L.; Schindler, R.H.; Schwitters, R.F.; Siegrist, J.L.; Strait, J.; Taureg, H.; Tonutti, M.; Trilling, G.H.; Vella, E.N.; Vidal, R.A.; Videau, I.; Weiss, J.M.; Zaccone, H.

    1980-04-07

    The decay mode psi' ..-->.. ..gamma gamma..psi has been studied with the Mark-II detector at SPEAR. New measurements of branching ratios for decays of the type psi' ..-->.. ..gamma..chi, chi ..-->.. ..gamma..psi involving known chi states are presented. The existence of a chi state of mass near 3455 MeV/c/sup 2/ produced in this decay chain is not confirmed, and the upper limit (90% confidence level) of the product of branching ratios is measured to be 0.13%. A new decay mode, psi' ..-->.. ..pi../sup 0/psi, which violates isospin conservation is observed with branching ratio (0.15 +- 0.06)%.

  6. Microwave absorbance properties of zirconium–manganese substituted cobalt nanoferrite as electromagnetic (EM) wave absorbers

    SciTech Connect

    Khan, Kishwar Rehman, Sarish

    2014-02-01

    Highlights: • Good candidates for EM materials with low reflectivity. • Good candidates for broad bandwidth at microwave frequency. • Microwave absorbing bandwidth was modulated simply by manipulating the Zr–Mn. • Higher the Zr–Mn content, the higher absorption rates for the electromagnetic radiation. • The predicted reflection loss shows that this can be used for thin ferrite absorber. - Abstract: Nanocrystalline Zr–Mn (x) substituted Co ferrite having chemical formula CoFe{sub 2−2x}Zr{sub x}Mn{sub x}O{sub 4} (x = 0.1–0.4) was prepared by co-precipitation technique. Combining properties such as structural, electrical, magnetic and reflection loss characteristics. Crystal structure and surface morphology of the calcined samples were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). By using two point probe homemade resistivity apparatus to find resistivity of the sample. Electromagnetic (EM) properties are measured through RF impedance/materials analyzer over 1 MHz–3 GHz. The room-temperature dielectric measurements show dispersion behavior with increasing frequency from 100 Hz to 3 MHz. Magnetic properties confirmed relatively strong dependence of saturation magnetization on Zr–Mn composition. Curie temperature is also found to decrease linearly with addition of Zr–Mn. Furthermore, comprehensive analysis of microwave reflection loss (RL) is carried out as a function of substitution, frequency, and thickness. Composition accompanying maximum microwave absorption is suggested.

  7. Gamma Oscillations and Visual Binding

    NASA Astrophysics Data System (ADS)

    Robinson, Peter A.; Kim, Jong Won

    2006-03-01

    At the root of visual perception is the mechanism the brain uses to analyze features in a scene and bind related ones together. Experiments show this process is linked to oscillations of brain activity in the 30-100 Hz gamma band. Oscillations at different sites have correlation functions (CFs) that often peak at zero lag, implying simultaneous firing, even when conduction delays are large. CFs are strongest between cells stimulated by related features. Gamma oscillations are studied here by modeling mm-scale patchy interconnections in the visual cortex. Resulting predictions for gamma responses to stimuli account for numerous experimental findings, including why oscillations and zero-lag synchrony are associated, observed connections with feature preferences, the shape of the zero-lag peak, and variations of CFs with attention. Gamma waves are found to obey the Schroedinger equation, opening the possibility of cortical analogs of quantum phenomena. Gamma instabilities are tied to observations of gamma activity linked to seizures and hallucinations.

  8. Dependence of TLD thermoluminescence yield on absorbed dose in a thermal neutron field.

    PubMed

    Gambarini, G; Roy, M S

    1997-01-01

    The emission from 6LiF and 7LiF thermoluminescence dosimeters (TLDs) exposed to the mixed field of thermal neutrons and gamma-rays of the thermal facility of a TRIGA MARK II nuclear reactor has been investigated for various thermal neutron fluences of the order of magnitude of those utilised in radiotherapy, with the purpose of investigating the reliability of TLD readouts in such radiation fields and of giving some information for better obtainment of the absorbed dose values. The emission after exposure in this mixed field is compared with the emission after gamma-rays only. The glow curves have been deconvoluted into gaussian peaks, and the differences in the characteristics of the peaks observed for the two radiation fields, having different linear energy transfers, and for different doses are shown. Irreversible radiation damage in dosimeters having high sensitivity to thermal neutrons is also reported, showing a memory effect of the previous thermal neutron irradiation history which is not restored by anneal treatment. PMID:9463872

  9. The Dortmund Low Background Facility - Low-background gamma ray spectrometry with an artificial overburden.

    PubMed

    Gastrich, Holger; Gößling, Claus; Klingenberg, Reiner; Kröninger, Kevin; Neddermann, Till; Nitsch, Christian; Quante, Thomas; Zuber, Kai

    2016-06-01

    The Dortmund Low Background Facility is an instrument for low-level gamma ray spectrometry with an artificial overburden of ten meters of water equivalent, an inner shielding, featuring a neutron absorber, and an active muon veto. An integral background count rate between 40keV and 2700keV of (2.528±0.004)counts/(kgmin) enables low-background gamma ray spectrometry with sensitivities in the range of some 10mBq/kg within a week of measurement time. PMID:27082973

  10. X-ray suppression in gamma-ray bursts through resonant Compton scattering

    NASA Technical Reports Server (NTRS)

    Brainerd, J. J.

    1992-01-01

    An X-ray that scatters with an electron in the first Landau level of a strong magnetic field is converted into a gamma ray. This process has a resonant cross section at X-ray energies and is therefore highly likely to occur even when the first Landau level is sparsely populated. Converted X-rays are cyclotron absorbed, maintaining the equilibrium between the cyclotron photon density and the population of the first Landau level. By suppressing a neutron star's black body emission, this mechanism can produce a gamma-ray burst with a low X-ray flux.

  11. gamma. -hexachlorocyclohexane (. gamma. -HCH) activates washed rabbit platelets

    SciTech Connect

    Lalau-Keraly, C.; Delautier, D.; Benveniste, J.; Puiseux-Dao, S.

    1986-03-01

    In guinea-pig macrophages, ..gamma..-HCH triggers activation of the phosphatidylinositol cycle and Ca/sup 2 +/ mobilization. Since these two biochemical events are also involved in platelet activation, the authors examined the effects of ..gamma..-HCH on washed rabbit platelets. Release of /sup 14/C-serotonin (/sup 14/C-5HT) and ATP from platelets prelabelled with /sup 14/C-5HT was measured simultaneously with aggregation. ..gamma..-HCH induced shape-change, aggregation and release reaction of platelets. Maximal aggregation (89 arbitrary units, AU), was observed using 170 ..mu..M ..gamma..-HCH, and was associated with 38.1 +/- 6.9% and 161 +/- 48 nM for /sup 14/C-5HT and ATP release respectively (mean +/- 1 SD, n=3). Using 80 ..mu..M ..gamma..-HCH yielded 18 AU, 12.8 +/- 1.0% and 27 +/- 14 nM for aggregation, C-5HT and ATP release respectively (n=3). No effect was observed with 40 ..mu.. M ..gamma..-HCH. Aspirin (ASA), a cyclooxygenase blocker, did not affect ..gamma..-HCH-induced platelet activation. Apyrase (APY), an ADP scavenger, inhibited by 90% aggregation induced by 170 ..mu..M ..gamma..-HCH and slightly inhibited (15%) the /sup 14/C-5HT release. In the presence of both ASA and APY, 96% inhibition of aggregation and 48% inhibition of /sup 14/C-5HT release were observed. Thus, ..gamma..-HCH induced platelet activation in a dose-dependent manner ADP, but not cyclooxygenase-dependent arachidonate metabolites, is involved in ..gamma..-HCH-induced aggregation, whereas, both appear to play a role in ..gamma..-HCH-induced release reaction.

  12. Simulation, fabrication and characterization of THz metamaterial absorbers.

    PubMed

    Grant, James P; McCrindle, Iain J H; Cumming, David R S

    2012-12-27

    Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical(1) and experimental demonstration(2) of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical(3), near IR(4), mid IR(5) , THz(6) , mm-wave(7) , microwave(8) and radio(9) bands. Applications include perfect lenses(10), sensors(11), telecommunications(12), invisibility cloaks(13) and filters(14,15). We have recently developed single band(16), dual band(17) and broadband(18) THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers(19). In our MM absorber the THz radiation is absorbed in a thickness of ~ λ/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems.

  13. Broadband ultrathin low-profile metamaterial microwave absorber

    NASA Astrophysics Data System (ADS)

    Sood, Deepak; Tripathi, Chandra Charu

    2016-04-01

    In this paper, a single-layer broadband low-profile ultrathin metamaterial microwave absorber is proposed for wide angle of incidence. The proposed absorber provides triple-band absorption under normal incidence of electromagnetic wave with two peaks lying in X-band and one in Ku-band. The unit cell is designed by using parametric optimization in such a way that the three peaks merge together to give broadband absorption. The absorber exhibits full width at half maxima bandwidth (FWHM) of 7.75 GHz from 7.55 to 15.30 GHz for wide angle of incidence up to 60° for both TE and TM polarizations. The mechanism of absorption of the absorber has been analyzed by field and surface current distributions. The proposed absorber has been fabricated and experimentally tested for different angles of incidence and polarization of the incident wave. The absorber is low profile with unit cell dimension of the order of 0.168 λ 0, and it is ultrathin with a thickness of ~ λ 0/17 at the center frequency of 11.43 GHz corresponding to the FWHM absorption bandwidth. This proposed absorber can be used for many potential applications such as stealth technology, cloaking and in antenna systems.

  14. Simulation, Fabrication and Characterization of THz Metamaterial Absorbers

    PubMed Central

    Grant, James P.; McCrindle, Iain J.H.; Cumming, David R.S.

    2012-01-01

    Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical1 and experimental demonstration2 of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical3, near IR4, mid IR5 , THz6 , mm-wave7 , microwave8 and radio9 bands. Applications include perfect lenses10, sensors11, telecommunications12, invisibility cloaks13 and filters14,15. We have recently developed single band16, dual band17 and broadband18 THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers19. In our MM absorber the THz radiation is absorbed in a thickness of ~ λ/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems. PMID:23299442

  15. Interaction of inhalational anaesthetics with CO2 absorbents.

    PubMed

    Baum, Jan A; Woehlck, Harvey J

    2003-03-01

    We review the currently available carbon dioxide absorbents: sodium hydroxide lime (=soda lime), barium hydroxide lime, potassium-hydroxide-free soda lime, calcium hydroxide lime and non-caustic lime. In general, all of these carbon dioxide absorbents are liable to react with inhalational anaesthetics. However, there is a decreasing reactivity of the different absorbents with inhalational anaesthetics: barium hydroxide lime > soda lime > potassium-hydroxide-free soda lime > calcium hydroxide lime and non-caustic lime. Gaseous compounds generated by the reaction of the anaesthetics with desiccated absorbents are those that threaten patients. All measures are comprehensively described to--as far as possible--prevent any accidental drying out of the absorbent. Whether or not compound A, a gaseous compound formed by the reaction of sevoflurane with normally hydrated absorbents, is still a matter of concern is discussed. Even after very high loading with this compound, during long-lasting low-flow sevoflurane anaesthesias, no clinical or laboratory signs of renal impairment were observed in any of the surgical patients. Finally, guidelines for the judicious use of different absorbents are given. PMID:12751549

  16. Practical multi-featured perfect absorber utilizing high conductivity silicon

    NASA Astrophysics Data System (ADS)

    Gok, Abdullah; Yilmaz, Mehmet; Bıyıklı, Necmi; Topallı, Kağan; Okyay, Ali K.

    2016-03-01

    We designed all-silicon, multi-featured band-selective perfect absorbing surfaces based on CMOS compatible processes. The center wavelength of the band-selective absorber can be varied between 2 and 22 μm while a bandwidth as high as 2.5 μm is demonstrated. We used a silicon-on-insulator (SOI) wafer which consists of n-type silicon (Si) device layer, silicon dioxide (SiO2) as buried oxide layer, and n-type Si handle layer. The center wavelength and bandwidth can be tuned by adjusting the conductivity of the Si device and handle layers as well as the thicknesses of the device and buried oxide layers. We demonstrate proof-of-concept absorber surfaces experimentally. Such absorber surfaces are easy to microfabricate because the absorbers do not require elaborate microfabrication steps such as patterning. Due to the structural simplicity, low-cost fabrication, wide spectrum range of operation, and band properties of the perfect absorber, the proposed multi-featured perfect absorber surfaces are promising for many applications. These include sensing devices, surface enhanced infrared absorption applications, solar cells, meta-materials, frequency selective sensors and modulators.

  17. Innovative Anti Crash Absorber for a Crashworthy Landing Gear

    NASA Astrophysics Data System (ADS)

    Guida, Michele; Marulo, Francesco; Montesarchio, Bruno; Bruno, Massimiliano

    2014-06-01

    This paper defines an innovative concept to anti-crash absorber in composite material to be integrated on the landing gear as an energy-absorbing device in crash conditions to absorb the impact energy. A composite cylinder tube in carbon fiber material is installed coaxially to the shock absorber cylinder and, in an emergency landing gear condition, collapses in order to enhance the energy absorption performance of the landing system. This mechanism has been developed as an alternative solution to a high-pressure chamber installed on the Agusta A129 CBT helicopter, which can be considered dangerous when the helicopter operates in hard and/or crash landing. The characteristics of the anti-crash device are presented and the structural layout of a crashworthy landing gear adopting the developed additional energy absorbing stage is outlined. Experimental and numerical results relevant to the material characterization and the force peaks evaluation of the system development are reported. The anti-crash prototype was designed, analysed, optimized, made and finally the potential performances of a landing gear with the additional anti-crash absorber system are tested by drop test and then correlated with a similar test without the anti-crash system, showing that appreciable energy absorbing capabilities and efficiencies can be obtained in crash conditions.

  18. Simulation, fabrication and characterization of THz metamaterial absorbers.

    PubMed

    Grant, James P; McCrindle, Iain J H; Cumming, David R S

    2012-01-01

    Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical(1) and experimental demonstration(2) of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical(3), near IR(4), mid IR(5) , THz(6) , mm-wave(7) , microwave(8) and radio(9) bands. Applications include perfect lenses(10), sensors(11), telecommunications(12), invisibility cloaks(13) and filters(14,15). We have recently developed single band(16), dual band(17) and broadband(18) THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers(19). In our MM absorber the THz radiation is absorbed in a thickness of ~ λ/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems. PMID:23299442

  19. Thin-film absorber for a solar collector

    SciTech Connect

    Wilhelm, W.G.

    1982-02-09

    This invention pertains to energy absorbers for solar collectors, and more particularly to high performance thin film absorbers. The solar collectors comprising the absorber of this invention overcome several problems seen in current systems, such as excessive hardware, high cost and unreliability. In the preferred form, the apparatus features a substantially rigid planar frame with a thin film window bonded to one planar side of the frame. An absorber in accordance with the present invention is comprised of two thin film layers that are sealed perimetrically. In a preferred embodiment, thin film layers are formed from a metal/plastic laminate. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. The absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

  20. Simultaneous beta and gamma spectroscopy

    DOEpatents

    Farsoni, Abdollah T.; Hamby, David M.

    2010-03-23

    A phoswich radiation detector for simultaneous spectroscopy of beta rays and gamma rays includes three scintillators with different decay time characteristics. Two of the three scintillators are used for beta detection and the third scintillator is used for gamma detection. A pulse induced by an interaction of radiation with the detector is digitally analyzed to classify the type of event as beta, gamma, or unknown. A pulse is classified as a beta event if the pulse originated from just the first scintillator alone or from just the first and the second scintillator. A pulse from just the third scintillator is recorded as gamma event. Other pulses are rejected as unknown events.

  1. Unified One-Dimensional Simulations of Gamma-Ray Line Emission from Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Milne, P. A.; Hungerford, A. L.; Fryer, C. L.; Evans, T. M.; Urbatsch, T. J.; Boggs, S. E.; Isern, J.; Bravo, E.; Hirschmann, A.; Kumagai, S.; Pinto, P. A.; The, L.-S.

    2004-10-01

    The light curves of Type Ia supernovae (SNe Ia) are powered by gamma rays emitted by the decay of radioactive elements such as 56Ni and its decay products. These gamma rays are downscattered, absorbed, and eventually reprocessed into the optical emission that makes up the bulk of all SN observations. Detection of the gamma rays that escape the expanding star provide the only direct means to study this power source for SN Ia light curves. Unfortunately, disagreements between calculations for the gamma-ray lines have made it difficult to interpret any gamma-ray observations. Here we present a detailed comparison of the major gamma-ray line transport codes for a series of one-dimensional SN Ia models. Discrepancies in past results were due to errors in the codes, and the corrected versions of the seven different codes yield very similar results. This convergence of the simulation results allows us to infer more reliable information from the current set of gamma-ray observations of SNe Ia. The observations of SN 1986G, SN 1991T, and SN 1998bu are consistent with explosion models based on their classification: subluminous, superluminous, and normally luminous, respectively.

  2. Improving degradation of paracetamol by integrating gamma radiation and Fenton processes.

    PubMed

    Cruz-González, Germán; Rivas-Ortiz, Iram B; González-Labrada, Katia; Rapado-Paneque, Manuel; Chávez-Ardanza, Armando; Nuevas-Paz, Lauro; Jáuregui-Haza, Ulises J

    2016-10-14

    Degradation of paracetamol (N-(4-hydroxiphenyl)acetamide) in aqueous solution by gamma radiation, gamma radiation/H2O2 and gamma radiation/Fenton processes was studied. Parameters affecting the radiolysis of paracetamol such as radiation dose, initial concentration of pollutant, pH and initial oxidant concentration were investigated. Gamma radiation was performed using a (60)Co source irradiator. Paracetamol degradation and mineralization increased with increasing absorbed radiation dose, but decreased with increasing initial concentration of the drug in aqueous solution. The addition of H2O2 resulted in an increased effect on irradiation-driven paracetamol degradation in comparison with the performance of the irradiation-driven process alone: paracetamol removal increased from 48.9% in the absence of H2O2 to 95.2% for H2O2 concentration of 41.7 mmol/L. However, the best results were obtained with gamma radiation/Fenton process with 100% of the drug removal at 5 kGy, for optimal H2O2 and Fe(2+) concentrations at 13.9 and 2.3 mmol/L, respectively, with a high mineralization of 63.7%. These results suggest gamma radiation/H2O2 and gamma radiation/Fenton processes as promising methods for paracetamol degradation in polluted wastewaters.

  3. In vitro absorption of gamma-globulin by neonatal intestinal epithelium of the pig.

    PubMed

    Lecce, J G

    1966-06-01

    1. An in vitro method, using fluorescent gamma-globulin and everted neonatal pig's intestinal slices, for the study of the active transport of large molecules is described.2. Uptake of gamma-globulin occurred within 15 min and required no exogenous substrates.3. In vitro absorption of gamma-globulin by intestinal epithelium was limited to the neonatal pig and 5-day-old mouse. No uptake was seen in intestines from a mature mouse, a pig with diarrhoea, a normal pig, a mature rabbit, a guinea-pig, a chick, and a chick embryo. Chick embryo yolk sac readily took up gamma-globulin.4. Rings of everted intestinal epithelium remained active (still absorbed gamma-globulin) after incubating for 4-6 hr in balanced salt solution (BSS).5. Uptake of gamma-globulin required oxygen and sodium and was reversibly inhibited by metabolic antagonists such as iodoacetate, arsenate, fluoride, 4,6-dinitro-varphi-cresol, phlorrhizin, anaerobiosis and cold. Under the conditions of the test, large colloidal molecules did not inhibit uptake of gamma-globulin.6. Similar results (although not as clear-cut) with metabolic inhibitors were obtained with preparations of chick embryo yolk sacs.7. Injuring mature pig's intestinal epithelium with surface-active agents did not produce non-specific absorption artifacts that resembled the specific absorption found in immature pig's intestinal epithelium.

  4. E6 Gamma Decay

    SciTech Connect

    Brown, B. Alex; Rae, W. D. M.

    2011-05-06

    Rare electric hexacontatetrapole (E6) transitions are studied in the full (f{sub 7/2},f{sub 5/2},p{sub 3/2},p{sub 1/2}) shell-model basis. Comparison of theory to the results from the gamma decay in {sup 53}Fe and from inelastic electron scattering on {sup 52}Cr provides unique and interesting tests of the valence wavefunctions, the models used for energy density functionals and into the origin of effective charge.

  5. Charmonium decays to {gamma}{pi}{sup 0}, {gamma}{eta}, and {gamma}{eta}{sup '}

    SciTech Connect

    Pedlar, T. K.; Xavier, J.; Cronin-Hennessy, D.; Gao, K. Y.; Hietala, J.; Klein, T.; Poling, R.; Zweber, P.; Dobbs, S.; Metreveli, Z.; Seth, K. K.; Tan, B. J. Y.; Tomaradze, A.; Libby, J.; Martin, L.; Powell, A.; Thomas, C.; Wilkinson, G.; Mendez, H.; Ge, J. Y.

    2009-06-01

    Using data acquired with the CLEO-c detector at the CESR e{sup +}e{sup -} collider, we measure branching fractions for J/{psi}, {psi}(2S), and {psi}(3770) decays to {gamma}{pi}{sup 0}, {gamma}{eta}, and {gamma}{eta}{sup '}. Defining R{sub n}{identical_to}B[{psi}(nS){yields}{gamma}{eta}]/B[{psi}(nS){yields}{gamma}{eta}{sup '}], we obtain R{sub 1}=(21.1{+-}0.9)% and, unexpectedly, an order of magnitude smaller limit, R{sub 2}<1.8% at 90% C.L. We also use J/{psi}{yields}{gamma}{eta}{sup '} events to determine branching fractions of improved precision for the five most copious {eta}{sup '} decay modes.

  6. Metamaterial perfect absorber based on artificial dielectric "atoms".

    PubMed

    Liu, Xiaoming; Bi, Ke; Li, Bo; Zhao, Qian; Zhou, Ji

    2016-09-01

    In this work, we numerically designed and then experimentally verified a metamaterial perfect absorber based on artificial dielectric "atoms". This metamaterial absorber is composed of dielectric ceramic material (SrTiO3) "atoms" embedded in a background matrix on a metal plate. The dielectric "atoms" couple strongly to the incident electric and magnetic fields at the Mie resonance mode, leading to the narrow perfect absorption band with simulated and experimental absorptivities of 99% and 98.5% at 8.96 GHz, respectively. The designed metamaterial perfect absorber is polarization insensitive and can operate in wide angle incidence.

  7. Automated Absorber Attachment for X-ray Microcalorimeter Arrays

    NASA Technical Reports Server (NTRS)

    Moseley, S.; Allen, Christine; Kilbourne, Caroline; Miller, Timothy M.; Costen, Nick; Schulte, Eric; Moseley, Samuel J.

    2007-01-01

    Our goal is to develop a method for the automated attachment of large numbers of absorber tiles to large format detector arrays. This development includes the fabrication of high quality, closely spaced HgTe absorber tiles that are properly positioned for pick-and-place by our FC150 flip chip bonder. The FC150 also transfers the appropriate minute amount of epoxy to the detectors for permanent attachment of the absorbers. The success of this development will replace an arduous, risky and highly manual task with a reliable, high-precision automated process.

  8. Towards Perfectly Absorbing Boundary Conditions for Euler Equations

    NASA Technical Reports Server (NTRS)

    Hayder, M. Ehtesham; Hu, Fang Q.; Hussaini, M. Yousuff

    1997-01-01

    In this paper, we examine the effectiveness of absorbing layers as non-reflecting computational boundaries for the Euler equations. The absorbing-layer equations are simply obtained by splitting the governing equations in the coordinate directions and introducing absorption coefficients in each split equation. This methodology is similar to that used by Berenger for the numerical solutions of Maxwell's equations. Specifically, we apply this methodology to three physical problems shock-vortex interactions, a plane free shear flow and an axisymmetric jet- with emphasis on acoustic wave propagation. Our numerical results indicate that the use of absorbing layers effectively minimizes numerical reflection in all three problems considered.

  9. HS 1603+3820 and its Warm Absorber

    NASA Astrophysics Data System (ADS)

    Nikołajuk, M.; Różańska, A.; Czerny, B.; Dobrzycki, A.

    2009-07-01

    We use photoionization codes CLOUDY and TITAN to obtain physical conditions in the absorbing medium close to the nucleus of a distant quasar (z = 2.54) HS 1603+3820. We found that the total column density of this Warm Absorber is 2 x 1022 cm-2. Due to the softness of the quasars spectrum the modelling allowed us also to determine uniquely the volume hydrogen density of this warm gas (n = 1010 cm-3) which combined with the other quasar parameters leads to a distance determination to the Warm Absorber from the central source which is ~ 1.5 x 1016 cm.

  10. Ultrabroadband absorber using a deep metallic grating with narrow slits

    NASA Astrophysics Data System (ADS)

    Liao, Yan-Lin; Zhao, Yan

    2015-01-01

    We report an ultrabroadband absorber using a deep metallic grating with narrow slits in the infrared regime. In this absorber, the ultrabroadband electromagnetic wave has been perfectly transmitted through the vacuum-grating interface due to the plasmonic Brewster angle effect, and its energy can attenuate effectively through the slits because of the enhanced electric field inside the slits. In addition, simulation results show that this ultrabroadband absorber works over a narrow angle range which is a very important feature of directional thermal source.

  11. Solar absorber material stability under high solar flux

    NASA Astrophysics Data System (ADS)

    Ignatiev, A.; Zajac, G.; Smith, G. B.

    1982-04-01

    Solar absorbing Black Chrome coatings have been exposed to high temperatures (350-400 C) under high solar fluxes (0.4 to 2.0 MW/sq m) to test for their stability under actual operating conditions. Field tests at the White Sands Solar Furnace have shown higher stability than expected from oven tested samples. Laboratory studies utilizing spectrally selective concentrated solar simulated radiation have indicated that the cause of the higher stability under solar irradiation is photo-stimulated desorption of oxygen bearing species at the absorber surface and resultant reduced oxidation of the absorber.

  12. Metamaterial perfect absorber based on artificial dielectric "atoms".

    PubMed

    Liu, Xiaoming; Bi, Ke; Li, Bo; Zhao, Qian; Zhou, Ji

    2016-09-01

    In this work, we numerically designed and then experimentally verified a metamaterial perfect absorber based on artificial dielectric "atoms". This metamaterial absorber is composed of dielectric ceramic material (SrTiO3) "atoms" embedded in a background matrix on a metal plate. The dielectric "atoms" couple strongly to the incident electric and magnetic fields at the Mie resonance mode, leading to the narrow perfect absorption band with simulated and experimental absorptivities of 99% and 98.5% at 8.96 GHz, respectively. The designed metamaterial perfect absorber is polarization insensitive and can operate in wide angle incidence. PMID:27607650

  13. Flexible subterahertz metamaterial absorber fabrication using inkjet printing technology

    NASA Astrophysics Data System (ADS)

    Lee, Dongju; Sung, Hyuk-Kee; Lim, Sungjoon

    2016-07-01

    In this study, a flexible metamaterial (MM) absorber was designed at 0.1 THz and fabricated using inkjet printing technology. The unit cell of the MM absorber was designed using a finite element method-based full-wave simulation. The unit cell comprised square rings, and it was printed with silver nanoparticle ink on flexible Kapton polyimide film. The fabrication processes were performed using a material printer. The absorber's reflection coefficient was measured using a vector network analyzer and a WR-10 waveguide. The absorption ratio was 93.5 % at 0.102 THz. Therefore, we demonstrated the possibility of inkjet printing at a subterahertz band.

  14. Fundamental research on oscillating water column wave power absorbers

    SciTech Connect

    Maeda, H.; Kato, W.; Kinoshita, T.; Masuda, K.

    1985-03-01

    An oscillating water column (OWC) wave power absorber is one of the most promising devices, as well as the Salter Duck and the Clam. This paper presents a simple prediction method, in which the equivalent floating body approximation is used, for absorbing wave power characteristics of an oscillating water column device. The effects of the compressibility of air and inertia of an air turbine and electric generator on absorbed wave power are obtained by using the equivalent electric circuit concept. Both the experimental and theoretical studies are carried out in this paper.

  15. 77 FR 31651 - Texas Gamma Ray, LLC, Pasadena, TX; Confirmatory Order (Effective Immediately)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-29

    ... current employees, new employees and annual refresher training will include the following elements: A... testing process. 2. Training Program Requirements. Training for current employees, new employees and... radiographers on the new procedures. Texas Gamma Ray, LLC, has also agreed to take the following...

  16. Annual Energy Review, 2008

    SciTech Connect

    2009-06-01

    The Annual Energy Review (AER) is the Energy Information Administration's (EIA) primary report of annual historical energy statistics. For many series, data begin with the year 1949. Included are statistics on total energy production, consumption, trade, and energy prices; overviews of petroleum, natural gas, coal, electricity, nuclear energy, renewable energy, and international energy; financial and environment indicators; and data unit conversions.

  17. Calculating the Muon Cooling within a MICE Solid and LiquidAbsorber

    SciTech Connect

    Yang, Stephanie Q.; Green, Michael A.; Virostek, Steve P.

    2006-06-10

    The key elements of the Muon Ionization Cooling Experiment (MICE) cooling channel are the absorbers that are a part of the MICE absorber focus coil modules (AFC modules). The boundaries of room temperature solid absorbers are well defined. The density of most solid absorber materials is also well understood. The properties of solid absorber are most certainly understood to 0.3 percent. The MICE liquid absorbers are different in that their dimensions are a function of the absorber temperature and the fluid pressure within the absorber. The second element in the liquid absorber is the variability of the liquid density with temperature and pressure. While one can determine the absorber boundary within 0.3 percent, the determination of the liquid density within 0.3 percent is more difficult (particularly with liquid helium in the absorber). This report presents a method of calculating absorber boundary and the cooling performance of the MICE absorbers as a function of fluid temperature and pressure.

  18. Diffuse gamma radiation

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

    1977-01-01

    An examination of the intensity, energy spectrum, and spatial distribution of the diffuse gamma-radiation observed by SAS-2 satellite away from the galactic plane in the energy range above 35 MeV has shown that it consists of two components. One component is generally correlated with galactic latitudes, the atomic hydrogen column density was deduced from 21 cm measurements, and the continuum radio emission, believed to be synchrotron emission. It has an energy spectrum similar to that in the plane and joins smoothly to the intense radiation from the plane. It is therefore presumed to be of galactic origin. The other component is apparently isotropic, at least on a coarse scale, and has a steep energy spectrum. No evidence is found for a cosmic ray halo surrounding the galaxy in the shape of a sphere or oblate spheroid with galactic dimensions. Constraints for a halo model with significantly larger dimensions are set on the basis of an upper limit to the gamma-ray anisotropy.

  19. New data on ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) partial photoneutron reactions

    SciTech Connect

    Varlamov, V. V. Ishkhanov, B. S.; Orlin, V. N.; Peskov, N. N.; Stepanov, M. E.

    2013-11-15

    Systematic discrepancies between the results of various experiments devoted to determining cross sections for total and partial photoneutron reactions are analyzed by using objective criteria of reliability of data in terms of the transitional photoneutron-multiplicity function F{sub i} = {sigma}({gamma}, in)/{sigma}({gamma}, xn), whose values for i = 1, 2, 3, ... cannot exceed by definition 1.00, 0.50, 0.33, ..., respectively. It was found that the majority of experimental data on the cross sections obtained for ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) reactions with the aid of methods of photoneutron multiplicity sorting do not meet objective criteria (in particular, F{sub 2} > 0.50 for a vast body of data). New data on the cross sections for partial reactions on {sup 181}Ta and {sup 208}Pb nuclei were obtained within a new experimental-theoretical method that was proposed for the evaluation of cross sections for partial reactions and in which the experimental neutron yield cross section {sigma}{sup expt}({gamma}, xn) = {sigma}({gamma}, n) + 2{sigma}({gamma}, 2n) + 3{sigma}({gamma}, 3n) + ..., which is free from problems associated with determining neutron multiplicities, is used simultaneously with the functions F{sub i}{sup theor} calculated within a combined model of photonuclear reactions.

  20. Superconducting gamma and fast-neutron spectrometers with high energy resolution

    DOEpatents

    Friedrich, Stephan; , Niedermayr, Thomas R.; Labov, Simon E.

    2008-11-04

    Superconducting Gamma-ray and fast-neutron spectrometers with very high energy resolution operated at very low temperatures are provided. The sensor consists of a bulk absorber and a superconducting thermometer weakly coupled to a cold reservoir, and determines the energy of the incident particle from the rise in temperature upon absorption. A superconducting film operated at the transition between its superconducting and its normal state is used as the thermometer, and sensor operation at reservoir temperatures around 0.1 K reduces thermal fluctuations and thus enables very high energy resolution. Depending on the choice of absorber material, the spectrometer can be configured either as a Gamma-spectrometer or as a fast-neutron spectrometer.

  1. Modification of silicone sealant to improve gamma radiation resistance, by addition of protective agents

    NASA Astrophysics Data System (ADS)

    González-Pérez, Giovanni; Burillo, Guillermina

    2013-09-01

    Poly (dimethylsiloxane) (PDMS) sealant (SS) was modified with the addition of different protective compounds to conserve its physical-chemical properties during gamma irradiation. 2-Vinyl naphthalene (2-VN), bisphenol-A (BPA) and poly (vinyl carbazole) (PVK) were used to evaluate radiation protection through the crosslinking effect of radiation. The samples were irradiated with doses from 100 kGy to 500 kGy at room temperature in air, with a 60Co gamma source, and the changes in molecular weight, thermal behavior, elastic properties and infrared spectra (FTIR-ATR) absorbance analysis were determined. The molecular weight of unmodified silicone sealant increases with the absorbed dose because of crosslinking as predominant effect. However, the crosslinking effect was inhibited with the addition of protective agent due to the aromatic compounds present. Modified silicone sealant films present better radiation resistance than unmodified system.

  2. Gamma irradiation of cultural artifacts for disinfection using Monte Carlo simulations.

    PubMed

    Choi, Jong-il; Yoon, Minchul; Kim, Dongho

    2012-11-01

    In this study, it has been investigated the disinfection of Korean cultural artifacts by gamma irradiation, simulating the absorbed dose distribution on the object with the Monte Carlo methodology. Fungal contamination was identified on two traditional Korean agricultural tools, Hongdukkae and Holtae, which had been stored in a museum. Nine primary species were identified from these items: Bjerkandera adusta, Dothideomycetes sp., Penicillium sp., Cladosporium tenuissimum, Aspergillus versicolor, Penicillium sp., Entrophospora sp., Aspergillus sydowii, and Corynascus sepedonium. However, these fungi were completely inactivated by gamma irradiation at an absorbed dose of 20kGy on the front side. Monte Carlo N Particle Transport Code was used to simulate the doses applied to these cultural artifacts, and the measured dose distributions were well predicted by the simulations. These results show that irradiation is effective for the disinfection of cultural artifacts and that dose distribution can be predicted with Monte Carlo simulations, allowing the optimization of the radiation treatment.

  3. THE TWO-PHASE, TWO-VELOCITY IONIZED ABSORBER IN THE SEYFERT 1 GALAXY NGC 5548

    SciTech Connect

    Andrade-Velazquez, Mercedes; Krongold, Yair; Binette, Luc; Jimenez-Bailon, Elena; Elvis, Martin; Nicastro, Fabrizio; Brickhouse, Nancy; Mathur, Smita

    2010-03-10

    We present an analysis of X-ray high-quality grating spectra of the Seyfert 1 galaxy NGC 5548 using archival Chandra-High Energy Transmission Grating Spectrometer and Low Energy Transmission Grating Spectrometer observations for a total exposure time of 800 ks. The continuum emission (between 0.2 keV and 8 keV) is well represented by a power law (GAMMA = 1.6) plus a blackbody component (kT = 0.1 keV). We find that the well-known X-ray warm absorber (WA) in this source consists of two different outflow velocity systems. One absorbing system has a velocity of -1110 +- 150 km s{sup -1} and the other of -490 +- 150 km s{sup -1}. Recognizing the presence of these kinematically distinct components allows each system to be fitted independently, each with two absorption components with different ionization levels. The high-velocity system consists of two components, one with a temperature of 2.7 +- 0.6 x 10{sup 6} K, log U = 1.23, and another with a temperature of 5.8 +- 1.0 x 10{sup 5} K, log U = 0.67. The high-velocity, high-ionization component produces absorption by charge states Fe XXI-XXIV, while the high-velocity, low-ionization component produces absorption by Ne IX-X, Fe XVII-XX, and O VII-VIII. The low-velocity system also required two absorbing components, one with a temperature of 5.8 +- 0.8 x 10{sup 5} K, log U = 0.67, producing absorption by Ne IX-X, Fe XVII-XX, and O VII-VIII, and the other with a lower temperature of 3.5 +- 0.35 x 10{sup 4} K and a lower ionization of log U = -0.49, producing absorption by O VI-VII and the Fe VII-XII M-shell Unresolved Transitions Array. Once these components are considered, the data do not require any further absorbers. In particular, a model consisting of a continuous radial range of ionization structures (as suggested by a previous analysis) is not required. The two absorbing components in each velocity system are in pressure equilibrium with each other. This suggests that each velocity system consists of a multi

  4. Carbon nanotube-based tandem absorber with tunable spectral selectivity: transition from near-perfect blackbody absorber to solar selective absorber.

    PubMed

    Selvakumar, N; Krupanidhi, S B; Barshilia, Harish C

    2014-04-23

    CVD grown CNT thin film with a thickness greater than 10 μm behaves like a near-perfect blackbody absorber (i.e., α/ε = 0.99/0.99). Whereas, for a thickness ≤ 0.4 µm, the CNT based tandem absorber acts as a spectrally selective coating (i.e., α/ε = 0.95/0.20). These selective coatings exhibit thermal stability up to 650 °C in vacuum, which can be used for solar thermal power generation. PMID:24474148

  5. Diagnostic beam absorber in Mu2e beam line

    SciTech Connect

    Rakhno, Igor; /Fermilab

    2011-03-01

    Star density, hadron flux, and residual dose distributions are calculated around the {mu}2e diagnostic beam absorber. Corresponding surface and ground water activation, and air activation are presented as well.

  6. Angular solar absorptance of absorbers used in solar thermal collectors.

    PubMed

    Tesfamichael, T; Wäckelgård, E

    1999-07-01

    The optical characterization of solar absorbers for thermal solar collectors is usually performed by measurement of the spectral reflectance at near-normal angle of incidence and calculation of the solar absorptance from the measured reflectance. The solar absorptance is, however, a function of the angle of incidence of the light impinging on the absorber. The total reflectance of two types of commercial solar-selective absorbers, nickel-pigmented anodized aluminum, and sputtered nickel nickel oxide coated aluminum are measured at angles of incidence from 5 to 80 in the wavelength range 300-2500 nm by use of an integrating sphere. From these measurements the angular integrated solar absorptance is determined. Experimental data are compared with theoretical calculations, and it is found that optical thin-film interference effects can explain the significant difference in solar absorptance at higher angles for the two types of absorbers.

  7. Microwave-absorbing properties of Co-filled carbon nanotubes

    SciTech Connect

    Lin Haiyan; Zhu Hong Guo Hongfan; Yu Liufang

    2008-10-02

    Co-filled carbon nanotubes composites were synthesized via using a simple and efficient wet chemistry solution method. The samples were characterized by transmission electron microscopy. Microwave-absorbing properties were investigated by measuring complex permittivity and complex permeability of the absorber in a frequency range of 2-18 GHz. The reflection loss (R.L.), matching frequency (f{sub m}) and matching thickness (d{sub m}) were calculated using the theory of the absorbing wall. The electromagnetic properties and microwave-absorbing characteristics effects of the modified carbon nanotubes by the encapsulation of metal Co were investigated. A matching thickness is found corresponding to a matching frequency. The maximum reflection loss is about -39.32 dB and the bandwidth corresponding to the reflection loss below -10 dB is 3.47 GHz. With increasing thickness, the maximum reflection loss shifts to lower frequency.

  8. Liquid absorbent solutions for separating nitrogen from natural gas

    DOEpatents

    Friesen, Dwayne T.; Babcock, Walter C.; Edlund, David J.; Lyon, David K.; Miller, Warren K.

    2000-01-01

    Nitrogen-absorbing and -desorbing compositions, novel ligands and transition metal complexes, and methods of using the same, which are useful for the selective separation of nitrogen from other gases, especially natural gas.

  9. Techniques for measuring intercepted and absorbed PAR in corn canopies

    NASA Technical Reports Server (NTRS)

    Gallo, K. P.; Daughtry, C. S. T.

    1984-01-01

    The quantity of radiation potentially available for photosynthesis that is captured by the crop is best described as absorbed photosynthetically active radiation (PAR). Absorbed PAR (APAR) is the difference between descending and ascending fluxes. The four components of APAR were measured above and within two planting densities of corn (Zea mays L.) and several methods of measuring and estimating APAR were examined. A line quantum sensor that spatially averages the photosynthetic photon flux density provided a rapid and portable method of measuring APAR. PAR reflectance from the soil (Typic Argiaquoll) surface decreased from 10% to less than 1% of the incoming PAR as the canopy cover increased. PAR reflectance from the canopy decreased to less than 3% at maximum vegetative cover. Intercepted PAR (1 - transmitted PAR) generally overestimated absorbed PAR by less than 4% throughout most of the growing season. Thus intercepted PAR appears to be a reasonable estimate of absorbed PAR.

  10. Tunable enhanced optical absorption of graphene using plasmonic perfect absorbers

    SciTech Connect

    Cai, Yijun; Zhu, Jinfeng; Liu, Qing Huo

    2015-01-26

    Enhancement and manipulation of light absorption in graphene is a significant issue for applications of graphene-based optoelectronic devices. In order to achieve this purpose in the visible region, we demonstrate a design of a graphene optical absorber inspired by metal-dielectric-metal metamaterial for perfect absorption of electromagnetic waves. The optical absorbance ratios of single and three atomic layer graphene are enhanced up to 37.5% and 64.8%, respectively. The graphene absorber shows polarization-dependence and tolerates a wide range of incident angles. Furthermore, the peak position and bandwidth of graphene absorption spectra are tunable in a wide wavelength range through a specific structural configuration. These results imply that graphene in combination with plasmonic perfect absorbers have a promising potential for developing advanced nanophotonic devices.

  11. Stretchable Metamaterial Absorber Using Liquid Metal-Filled Polydimethylsiloxane (PDMS)

    PubMed Central

    Kim, Kyeongseob; Lee, Dongju; Eom, Seunghyun; Lim, Sungjoon

    2016-01-01

    A stretchable metamaterial absorber is proposed in this study. The stretchability was achieved by liquid metal and polydimethylsiloxane (PDMS). To inject liquid metal, microfluidic channels were fabricated using PDMS powers and microfluidic-channel frames, which were built using a three-dimensional printer. A top conductive pattern and ground plane were designed after considering the easy injection of liquid metal. The proposed metamaterial absorber comprises three layers of PDMS substrate. The top layer is for the top conductive pattern, and the bottom layer is for the meandered ground plane. Flat PDMS layers were inserted between the top and bottom PDMS layers. The measured absorptivity of the fabricated absorber was 97.8% at 18.5 GHz, and the absorption frequency increased from 18.5 to 18.65 GHz as the absorber was stretched from its original length (5.2 cm) to 6.4 cm. PMID:27077861

  12. [Study on absorbing volatile oil with mesoporous carbon].

    PubMed

    Yan, Hong-mei; Jia, Xiao-bin; Zhang, Zhen-hai; Sun, E; Yang Nan

    2014-11-01

    Clove oil and turmeric oil were absorbed by mesoporous carbon. The absorption ratio of mesoporous carbon to volatile oil was optimized with the eugenol yield and curcumol yield as criteria Curing powder was characterized by scanning electron microscopy (SEM) and differential scanning calorietry (DSC). The effects of mesoporous carbon on dissolution in vitro and thermal stability of active components were studied. They reached high adsorption rate when the absorption ratio of mesoporous carbon to volatile oil was 1:1. When volatile oil was absorbed, dissolution rate of active components had a little improvement and their thermal stability improved after volatile oil was absorbed by the loss rate decreasing more than 50%. Absorbing herbal volatile oil with mesoporous carbon deserves further studying. PMID:25850263

  13. 21 CFR 878.4840 - Absorbable polydioxanone surgical suture.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable... expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and with...

  14. 21 CFR 878.4840 - Absorbable polydioxanone surgical suture.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable... expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and with...

  15. 21 CFR 878.4840 - Absorbable polydioxanone surgical suture.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable... expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and with...

  16. 21 CFR 878.4840 - Absorbable polydioxanone surgical suture.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable... expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and with...

  17. 21 CFR 878.4840 - Absorbable polydioxanone surgical suture.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4840 Absorbable... expected to occur, and ophthalmic surgery. It may be coated or uncoated, undyed or dyed, and with...

  18. Tunable enhanced optical absorption of graphene using plasmonic perfect absorbers

    NASA Astrophysics Data System (ADS)

    Cai, Yijun; Zhu, Jinfeng; Liu, Qing Huo

    2015-01-01

    Enhancement and manipulation of light absorption in graphene is a significant issue for applications of graphene-based optoelectronic devices. In order to achieve this purpose in the visible region, we demonstrate a design of a graphene optical absorber inspired by metal-dielectric-metal metamaterial for perfect absorption of electromagnetic waves. The optical absorbance ratios of single and three atomic layer graphene are enhanced up to 37.5% and 64.8%, respectively. The graphene absorber shows polarization-dependence and tolerates a wide range of incident angles. Furthermore, the peak position and bandwidth of graphene absorption spectra are tunable in a wide wavelength range through a specific structural configuration. These results imply that graphene in combination with plasmonic perfect absorbers have a promising potential for developing advanced nanophotonic devices.

  19. Energy deposition studies for the LBNE beam absorber

    SciTech Connect

    Rakhno, Igor L.; Mokhov, Nikolai V.; Tropin, Igor S.

    2015-01-29

    Results of detailed Monte Carlo energy deposition studies performed for the LBNE absorber core and the surrounding shielding with the MARS15 code are described. The model of the entire facility, that includes a pion-production target, focusing horns, target chase, decay channel, hadron absorber system – all with corresponding radiation shielding – was developed using the recently implemented ROOT-based geometry option in the MARS15 code. This option provides substantial flexibility and automation when developing complex geometry models. Both normal operation and accidental conditions were studied. Various design options were considered, in particular the following: (i) filling the decay pipe with air or helium; (ii) the absorber mask material and shape; (iii) the beam spoiler material and size. Results of detailed thermal calculations with the ANSYS code helped to select the most viable absorber design options.

  20. 48. Bottom of shock absorber, bottom of launch tube, soda ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    48. Bottom of shock absorber, bottom of launch tube, soda bottle liter at right - Ellsworth Air Force Base, Delta Flight, Launch Facility, On County Road T512, south of Exit 116 off I-90, Interior, Jackson County, SD

  1. Two-dimensional QR-coded metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Sui, Sai; Ma, Hua; Wang, Jiafu; Pang, Yongqiang; Zhang, Jieqiu; Qu, Shaobo

    2016-01-01

    In this paper, the design of metamaterial absorbers is proposed based on QR coding and topology optimization. Such absorbers look like QR codes and can be recognized by decoding softwares as well as mobile phones. To verify the design, two lightweight wideband absorbers are designed, which can achieve wideband absorption above 90 % in 6.68-19.30 and 7.00-19.70 GHz, respectively. More importantly, polarization-independent absorption over 90 % can be maintained under incident angle within 55°. The QR code absorber not only can achieve wideband absorption, but also can carry information such as texts and Web sites. They are of important values in applications such identification and electromagnetic protection.

  2. Absorbing boundary conditions for second-order hyperbolic equations

    NASA Technical Reports Server (NTRS)

    Jiang, Hong; Wong, Yau Shu

    1989-01-01

    A uniform approach to construct absorbing artificial boundary conditions for second-order linear hyperbolic equations is proposed. The nonlocal boundary condition is given by a pseudodifferential operator that annihilates travelling waves. It is obtained through the dispersion relation of the differential equation by requiring that the initial-boundary value problem admits the wave solutions travelling in one direction only. Local approximation of this global boundary condition yields an nth-order differential operator. It is shown that the best approximations must be in the canonical forms which can be factorized into first-order operators. These boundary conditions are perfectly absorbing for wave packets propagating at certain group velocities. A hierarchy of absorbing boundary conditions is derived for transonic small perturbation equations of unsteady flows. These examples illustrate that the absorbing boundary conditions are easy to derive, and the effectiveness is demonstrated by the numerical experiments.

  3. Gamma-hadron families and scaling violation

    NASA Technical Reports Server (NTRS)

    Gaisser, T. K.; Stanev, T.; Wrotniak, J. A.

    1985-01-01

    For three different interaction models we have simulated gamma-hadron families, including the detector (Pamir emulsion chamber) response. Rates of gamma families, hadrons, and hadron-gamma ratios were compared with experiments.

  4. The Compton Gamma Ray Observatory

    NASA Astrophysics Data System (ADS)

    Gehrels, N.; Chipman, E.; Kniffen, D.

    1994-06-01

    The Arthur Holly Compton Gamma Ray Observatory Compton) is the second in NASA's series of great Observatories. Launched on 1991 April 5, Compton represents a dramatic increase in capability over previous gamma-ray missions. The spacecraft and scientific instruments are all in good health, and many significant discoveries have already been made. We describe the capabilities of the four scientific instruments, and the observing program of the first 2 years of the mission. Examples of early discoveries by Compton are enumerated, including the discovery that gamma-ray bursts are isotropic but spatially inhomogeneous in their distribution; the discovery of a new class of high-energy extragalacatic gamma-ray sources, the gamma-ray AGNs; the discovery of emission from SN 1987A in the nuclear line of Co-57; and the mapping of emission from Al-26 in the interstellar medium (ISM) near the Galactic center. Future observations will include deep surveys of selected regions of the sky, long-tem studies of individual objects, correlative studies of objects at gamma-ray and other energies, a Galactic plane survey at intermediate gamma-ray energies, and improved statistics on gamma-ray bursts to search for small anisotropies. After completion of the all-sky survey, a Guest Investigator program is in progress with guest observers' time share increasing from 30% upward for the late mission phases.

  5. High energy gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Fichtel, Carl E.

    1987-01-01

    High energy gamma ray astronomy has evolved with the space age. Nonexistent twenty-five years ago, there is now a general sketch of the gamma ray sky which should develop into a detailed picture with the results expected to be forthcoming over the next decade. The galactic plane is the dominant feature of the gamma ray sky, the longitude and latitude distribution being generally correlated with galactic structural features including the spiral arms. Two molecular clouds were already seen. Two of the three strongest gamma ray sources are pulsars. The highly variable X-ray source Cygnus X-3 was seen at one time, but not another in the 100 MeV region, and it was also observed at very high energies. Beyond the Milky Way Galaxy, there is seen a diffuse radiation, whose origin remains uncertain, as well as at least one quasar, 3C 273. Looking to the future, the satellite opportunities for high energy gamma ray astronomy in the near term are the GAMMA-I planned to be launched in late 1987 and the Gamma Ray Observatory, scheduled for launch in 1990. The Gamma Ray Observatory will carry a total of four instruments covering the entire energy range from 30,000 eV to 3 x 10 to the 10th eV with over an order of magnitude increase in sensitivity relative to previous satellite instruments.

  6. Cyclic oxidation behavior of beta+gamma overlay coatings on gamma and gamma+gamma-prime alloys

    NASA Technical Reports Server (NTRS)

    Nesbitt, J. A.; Pilsner, B. H.; Carol, L. A.; Heckel, R. W.

    1984-01-01

    Detailed experimental studies of the cyclic oxidation behavior of low-pressure plasma sprayed beta+gamma coasting on gamma-phase Ni-Cr-Al alloys have shown the correlation of weight change, oxide type, and Cr and Al concentration-distance profiles as a function of oxidation time. Of special interest was the transition to breakway oxidation due to the loss of the Al flux to the oxide and the failure of the coated alloy to form an Al2O3-rich oxide scale. The experimental results on beta+gamma/gamma coating systems were used as the basis of a numerical model (ternary, semi-infinite, finite-difference analysis) which accurately predicted changes in Cr and Al concentration-distance profiles. The model was used to study parameters critical to enhancing the life of coatings which fail by a combination of Al loss in forming the oxide scale and Al loss via interdiffusion with the substrate alloy. Comparisons of beta+gamma/gamma coating behavior are made to the oxidation of coated gamma+gamma-prime substrates, both ternary Ni-Cr-Al alloys and Mar-M 247-type alloys.

  7. Gamma spectroscopy of environmental samples

    NASA Astrophysics Data System (ADS)

    Siegel, P. B.

    2013-05-01

    We describe experiments for the undergraduate laboratory that use a high-resolution gamma detector to measure radiation in environmental samples. The experiments are designed to instruct the students in the quantitative analysis of gamma spectra and secular equilibrium. Experiments include the radioactive dating of Brazil nuts, determining radioisotope concentrations in natural samples, and measurement of the 235U abundance in uranium rich rocks.

  8. Gamma-ray line astrophysics

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.; Ramaty, R.

    1986-01-01

    Recent observations of gamma-ray line emission from solar flares, gamma-ray bursts, the galactic center, the interstellar medium and the jets of SS433 are reviewed. The implications of these observations on high energy processes in these sources are discussed.

  9. Light Absorbing Particle (LAP) Measurements in the Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Baumgardner, D.; Raga, G. B.; Anderson, B.; Diskin, G.; Sachse, G.; Kok, G.

    2003-01-01

    This viewgraph presentation covers the capabilities and design of the Single Particle Soot Photometer (SP-2), and reviews its role on the Sage III Ozone Loss Validation Experiment (SOLVE II) field campaign during 2003. On SOLVE II the SP-2 was carried into the Arctic onboard a DC-8 aircraft, in order to determine the size distribution of light-absorbing and non light-absorbing particles in the stratosphere. Graphs and tables relate some of the results from SOLVE II.

  10. Design of integration-ready metasurface-based infrared absorbers

    SciTech Connect

    Ogando, Karim Pastoriza, Hernán

    2015-07-28

    We introduce an integration ready design of metamaterial infrared absorber, highly compatible with many kinds of fabrication processes. We present the results of an exhaustive experimental characterization, including an analysis of the effects of single meta-atom geometrical parameters and collective arrangement. We confront the results with the theoretical interpretations proposed in the literature. Based on the results, we develop a set of practical design rules for metamaterial absorbers in the infrared region.

  11. Novel Ultraviolet Light Absorbing Polymers For Optical Applications

    NASA Astrophysics Data System (ADS)

    Doddi, Namassivaya; Yamada, Akira; Dunks, Gary B.

    1988-07-01

    Ultraviolet light absorbing monomers have been developed that can be copolymerized with acrylates. The composition of the resultant stable copolymers can be adjusted to totally block the transmission of light below about 430 nm. Fabrication of lenses from the materials is accomplished by lathe cutting and injection molding procedures. These ultraviolet light absorbing materials are non-mutagenic and non-toxic and are currently being used in intraocular lenses.

  12. Impact-absorbing characteristics by applying ultrasonic vibration

    NASA Astrophysics Data System (ADS)

    Suzuki, Atsuyuki; Ueki, Eiichiro; Tsujino, Jiromaru

    2012-05-01

    An impact-absorbing device that facilitates the application of ultrasonic vibrations was devised. Vibration distributions, springback characteristics, and impact-absorption characteristics were measured. We confirm that the springback amount decreases and the impact is absorbed upon the application of ultrasonic vibrations. When an aluminum alloy plate is crumpled, the maximum output voltage of the attached shock sensor decreases to 65% upon the application of ultrasonic vibrations as compared to when the ultrasonic vibrations are not applied.

  13. Neutron absorbing room temperature vulcanizable silicone rubber compositions

    DOEpatents

    Zoch, Harold L.

    1979-11-27

    A neutron absorbing composition comprising a one-component room temperature vulcanizable silicone rubber composition or a two-component room temperature vulcanizable silicone rubber composition in which the composition contains from 25 to 300 parts by weight based on the base silanol or vinyl containing diorganopolysiloxane polymer of a boron compound or boron powder as the neutron absorbing ingredient. An especially useful boron compound in this application is boron carbide.

  14. The Workshop on Microwave-Absorbing Materials for Accelerators

    SciTech Connect

    Isidoro Campisi

    1993-05-01

    A workshop on the physics and applications of microwave-absorbing materials in accelerators and related systems was held at CEBAF February 22-24, 1993. The gathering brought together about 150 scientists and representatives of industries from all over the world. The main topics of discussion were the properties of ''absorbing'' materials and how the stringent conditions in an accelerator environment restrict the choice of usable material.

  15. Calirimeter/absorber optimization for a RHIC dimuon experiment

    SciTech Connect

    Aronson, S.H.; Murtagh, M.J.; Starks, M.; Liu, X.T.; Petitt, G.A.; Zhang, Z.; Ewell, L.A.; Hill, J.C.; Wohn, F.K.; Costales, J.B.; Namboodiri, M.N., Sangster, T.C.; Thomas, J.H.; Gavron, A.; Waters, L.; Kehoe, W.L.; Steadman, S.G.; Awes, T.C.; Obenshain, F.E.; Saini, S.; Young, G.R.; Chang, J.; Fung, S.Y.; Kang, J.H.; Kreke, J.; He, Xiaochun, Sorensen, S.P.; Cornell, E.C.; Maguire, C.F.

    1991-12-31

    The RD-10 R&D effort on calorimeter/absorber optimization for a RHIC experiment had an extended run in 1991 using the A2 test beam at the AGS. Measurements were made of the leakage of particles behind various model hadron calorimeters. Behavior of the calorimeter/absorber as a muon-identifier was studied. First comparisons of results from test measurements to calculated results using the GHEISHA code were made

  16. Structural ordering of multi-walled carbon nanotubes (MWCNTs) caused by gamma (γ)-ray irradiation

    SciTech Connect

    Silambarasan, D. Vasu, V.; Iyakutti, K.; Asokan, K.

    2015-06-24

    Multi-walled carbon nanotubes (MWCNTs) were irradiated by Gamma (γ)-rays in air with absorbed doses of 25 and 50 kGy. As a result of γ-ray irradiation, the inter-wall distance of MWCNTs was decreased and their graphitic order was improved. The reduction in inter-wall distance and structural ordering was improved with the increasing dosage of irradiation. Experimental evidences are provided by powder XRD and micro-Raman analyses.

  17. Investigations on laser transmission welding of absorber-free thermoplastics

    NASA Astrophysics Data System (ADS)

    Mamuschkin, Viktor; Olowinsky, Alexander; Britten, Simon W.; Engelmann, Christoph

    2014-03-01

    Within the plastic industry laser transmission welding ranks among the most important joining techniques and opens up new application areas continuously. So far, a big disadvantage of the process was the fact that the joining partners need different optical properties. Since thermoplastics are transparent for the radiation of conventional beam sources (800- 1100 nm) the absorbance of one of the joining partners has to be enhanced by adding an infrared absorber (IR-absorber). Until recently, welding of absorber-free parts has not been possible. New diode lasers provide a broad variety of wavelengths which allows exploiting intrinsic absorption bands of thermoplastics. The use of a proper wavelength in combination with special optics enables laser welding of two optically identical polymer parts without absorbers which can be utilized in a large number of applications primarily in the medical and food industry, where the use of absorbers usually entails costly and time-consuming authorization processes. In this paper some aspects of the process are considered as the influence of the focal position, which is crucial when both joining partners have equal optical properties. After a theoretical consideration, an evaluation is carried out based on welding trials with polycarbonate (PC). Further aspects such as gap bridging capability and the influence of thickness of the upper joining partner are investigated as well.

  18. Spectral estimators of absorbed photosynthetically active radiation in corn canopies

    NASA Technical Reports Server (NTRS)

    Gallo, K. P.; Daughtry, C. S. T.; Bauer, M. E.

    1984-01-01

    Most models of crop growth and yield require an estimate of canopy leaf area index (LAI) or absorption of radiation. Relationships between photosynthetically active radiation (PAR) absorbed by corn canopies and the spectral reflectance of the canopies were investigated. Reflectance factor data were acquired with a LANDSAT MSS band radiometer. From planting to silking, the three spectrally predicted vegetation indices examined were associated with more than 95% of the variability in absorbed PAR. The relationships developed between absorbed PAR and the three indices were evaluated with reflectance factor data acquired from corn canopies planted in 1979 through 1982. Seasonal cumulations of measured LAI and each of the three indices were associated with greater than 50% of the variation in final grain yields from the test years. Seasonal cumulations of daily absorbed PAR were associated with up to 73% of the variation in final grain yields. Absorbed PAR, cumulated through the growing season, is a better indicator of yield than cumulated leaf area index. Absorbed PAR may be estimated reliably from spectral reflectance data of crop canopies.

  19. Design principle of a nonlinear robust dynamic vibration absorber

    NASA Astrophysics Data System (ADS)

    Koga, Yuki; Masuda, Arata

    2016-04-01

    This study aims to develop a design principle of a nonlinear dynamic vibration absorber focusing on its robustness against the alteration of the natural frequency of the primary system. To this end, a 2-DOF coupled system consisting of the primary and absorber systems is analytically solved to evaluate the maximally possible level of the displacement response of the primary system by means of averaging method. In this approach, the equation of motion of the vibration absorber is first solved in the steady-state by the averaging method for a given amplitude of the primary system assuming that the whole responses of the coupled system have the same frequency as the excitation force. Then, the equivalent dynamic stiffness of the dynamic absorber is derived which represents how the absorber acts on the primary system in reaction of the displacement of the primary system. Because the maximally possible displacement amplitude of the primary system is enveloped by the reciprocal of the imaginary part of the equivalent dynamic stiffness, the benefit of introducing a softening effect into the design of the dynamic absorber is theoretically suggested, and validated through numerical simulations.

  20. Wideband-Switchable Metamaterial Absorber Using Injected Liquid Metal.

    PubMed

    Kim, Hyung Ki; Lee, Dongju; Lim, Sungjoon

    2016-01-01

    Metamaterial absorbers can provide good solutions for radar-cross-section (RCS) reduction. In spite of their attractive features of thinness, lightness, and low cost, resonant metamaterial absorbers have a drawback of narrow bandwidth. For practical radar applications, wideband absorbers are necessary. In this paper, we propose a wideband-switchable metamaterial absorber using liquid metal. In order to reduce RCS both for X-band and C-band, the switchable Jerusalem cross (JC) resonator is introduced. The JC resonator consists of slotted circular rings, chip resistors, and microfluidic channels. The JC resonator is etched on a flexible printed circuit board (FPCB), and the microfluidic channels are laser-etched on a polydimethylsiloxane (PDMS) material. The proposed absorber can switch the absorption frequency band by injecting a liquid metal alloy into the channels. The performance of the absorber was demonstrated through full-wave simulation and through measurements employing prototypes. The experimental results showed absorption ratios of over 90% from 7.43 GHz to 14.34 GHz, and from 5.62 GHz to 7.3 GHz, with empty channels and liquid metal-filled channels, respectively. Therefore, the absorption band was successfully switched between the C-band (4-8 GHz) and the X-band (8-12 GHz) by injecting liquid metal eutectic gallium indium alloy (EGaIn) into the channels. PMID:27546310

  1. Delayed-feedback vibration absorbers to enhance energy harvesting

    NASA Astrophysics Data System (ADS)

    Kammer, Ayhan S.; Olgac, Nejat

    2016-02-01

    Recovering energy from ambient vibrations has recently been a popular research topic. This article is conceived as a concept study that explores new directions to enhance the performance of such energy harvesting devices from base excitation. The main idea revolves around the introduction of delayed feedback sensitization (or tuning) of an active vibration absorber setup. To clarify the concept, the Delayed Resonator theory is reviewed and its suitability for energy harvesting purposes is studied. It is recognized that an actively tuned and purely resonant absorber is infeasible for such applications. The focus is then shifted to alternative tuning schemes that deviate from resonance conditions. Also called Delayed Feedback Vibration Absorbers, these devices may indeed provide significant enhancements in energy harvesting capacity. Analytical developments are presented to study energy generation and consumption characteristics. Effects of excitation frequency and absorber damping are investigated. The influences of time-delayed feedback on the stability and the transient performance of the system are also treated. The analysis starts from a stand-alone absorber, emulating seismic mass type harvesters. The work is then extended to vibration control applications, where an absorber/harvester is coupled with a primary structure. The results are demonstrated with numerical simulations on a case study.

  2. Wideband-Switchable Metamaterial Absorber Using Injected Liquid Metal

    NASA Astrophysics Data System (ADS)

    Kim, Hyung Ki; Lee, Dongju; Lim, Sungjoon

    2016-08-01

    Metamaterial absorbers can provide good solutions for radar-cross-section (RCS) reduction. In spite of their attractive features of thinness, lightness, and low cost, resonant metamaterial absorbers have a drawback of narrow bandwidth. For practical radar applications, wideband absorbers are necessary. In this paper, we propose a wideband-switchable metamaterial absorber using liquid metal. In order to reduce RCS both for X-band and C-band, the switchable Jerusalem cross (JC) resonator is introduced. The JC resonator consists of slotted circular rings, chip resistors, and microfluidic channels. The JC resonator is etched on a flexible printed circuit board (FPCB), and the microfluidic channels are laser-etched on a polydimethylsiloxane (PDMS) material. The proposed absorber can switch the absorption frequency band by injecting a liquid metal alloy into the channels. The performance of the absorber was demonstrated through full-wave simulation and through measurements employing prototypes. The experimental results showed absorption ratios of over 90% from 7.43 GHz to 14.34 GHz, and from 5.62 GHz to 7.3 GHz, with empty channels and liquid metal-filled channels, respectively. Therefore, the absorption band was successfully switched between the C-band (4-8 GHz) and the X-band (8-12 GHz) by injecting liquid metal eutectic gallium indium alloy (EGaIn) into the channels.

  3. Wideband-Switchable Metamaterial Absorber Using Injected Liquid Metal

    PubMed Central

    Kim, Hyung Ki; Lee, Dongju; Lim, Sungjoon

    2016-01-01

    Metamaterial absorbers can provide good solutions for radar-cross-section (RCS) reduction. In spite of their attractive features of thinness, lightness, and low cost, resonant metamaterial absorbers have a drawback of narrow bandwidth. For practical radar applications, wideband absorbers are necessary. In this paper, we propose a wideband-switchable metamaterial absorber using liquid metal. In order to reduce RCS both for X-band and C-band, the switchable Jerusalem cross (JC) resonator is introduced. The JC resonator consists of slotted circular rings, chip resistors, and microfluidic channels. The JC resonator is etched on a flexible printed circuit board (FPCB), and the microfluidic channels are laser-etched on a polydimethylsiloxane (PDMS) material. The proposed absorber can switch the absorption frequency band by injecting a liquid metal alloy into the channels. The performance of the absorber was demonstrated through full-wave simulation and through measurements employing prototypes. The experimental results showed absorption ratios of over 90% from 7.43 GHz to 14.34 GHz, and from 5.62 GHz to 7.3 GHz, with empty channels and liquid metal-filled channels, respectively. Therefore, the absorption band was successfully switched between the C-band (4–8 GHz) and the X-band (8–12 GHz) by injecting liquid metal eutectic gallium indium alloy (EGaIn) into the channels. PMID:27546310

  4. Wideband-Switchable Metamaterial Absorber Using Injected Liquid Metal.

    PubMed

    Kim, Hyung Ki; Lee, Dongju; Lim, Sungjoon

    2016-08-22

    Metamaterial absorbers can provide good solutions for radar-cross-section (RCS) reduction. In spite of their attractive features of thinness, lightness, and low cost, resonant metamaterial absorbers have a drawback of narrow bandwidth. For practical radar applications, wideband absorbers are necessary. In this paper, we propose a wideband-switchable metamaterial absorber using liquid metal. In order to reduce RCS both for X-band and C-band, the switchable Jerusalem cross (JC) resonator is introduced. The JC resonator consists of slotted circular rings, chip resistors, and microfluidic channels. The JC resonator is etched on a flexible printed circuit board (FPCB), and the microfluidic channels are laser-etched on a polydimethylsiloxane (PDMS) material. The proposed absorber can switch the absorption frequency band by injecting a liquid metal alloy into the channels. The performance of the absorber was demonstrated through full-wave simulation and through measurements employing prototypes. The experimental results showed absorption ratios of over 90% from 7.43 GHz to 14.34 GHz, and from 5.62 GHz to 7.3 GHz, with empty channels and liquid metal-filled channels, respectively. Therefore, the absorption band was successfully switched between the C-band (4-8 GHz) and the X-band (8-12 GHz) by injecting liquid metal eutectic gallium indium alloy (EGaIn) into the channels.

  5. Spectral estimators of absorbed photosynthetically active radiation in corn canopies

    NASA Technical Reports Server (NTRS)

    Gallo, K. P.; Daughtry, C. S. T.; Bauer, M. E.

    1985-01-01

    Most models of crop growth and yield require an estimate of canopy leaf area index (LAI) or absorption of radiation. Relationships between photosynthetically active radiation (PAR) absorbed by corn canopies and the spectral reflectance of the canopies were investigated. Reflectance factor data were acquired with a Landsat MSS band radiometer. From planting to silking, the three spectrally predicted vegetation indices examined were associated with more than 95 percent of the variability in absorbed PAR. The relationships developed between absorbed PAR and the three indices were evaluated with reflectance factor data acquired from corn canopies planted in 1979 through 1982. Seasonal cumulations of measured LAI and each of the three indices were associated with greater than 50 percent of the variation in final grain yields from the test years. Seasonal cumulations of daily absorbed PAR were associated with up to 73 percent of the variation in final grain yields. Absorbed PAR, cumulated through the growing season, is a better indicator of yield than cumulated leaf area index. Absorbed PAR may be estimated reliably from spectral reflectance data of crop canopies.

  6. Wideband-Switchable Metamaterial Absorber Using Injected Liquid Metal

    NASA Astrophysics Data System (ADS)

    Kim, Hyung Ki; Lee, Dongju; Lim, Sungjoon

    2016-08-01

    Metamaterial absorbers can provide good solutions for radar-cross-section (RCS) reduction. In spite of their attractive features of thinness, lightness, and low cost, resonant metamaterial absorbers have a drawback of narrow bandwidth. For practical radar applications, wideband absorbers are necessary. In this paper, we propose a wideband-switchable metamaterial absorber using liquid metal. In order to reduce RCS both for X-band and C-band, the switchable Jerusalem cross (JC) resonator is introduced. The JC resonator consists of slotted circular rings, chip resistors, and microfluidic channels. The JC resonator is etched on a flexible printed circuit board (FPCB), and the microfluidic channels are laser-etched on a polydimethylsiloxane (PDMS) material. The proposed absorber can switch the absorption frequency band by injecting a liquid metal alloy into the channels. The performance of the absorber was demonstrated through full-wave simulation and through measurements employing prototypes. The experimental results showed absorption ratios of over 90% from 7.43 GHz to 14.34 GHz, and from 5.62 GHz to 7.3 GHz, with empty channels and liquid metal-filled channels, respectively. Therefore, the absorption band was successfully switched between the C-band (4–8 GHz) and the X-band (8–12 GHz) by injecting liquid metal eutectic gallium indium alloy (EGaIn) into the channels.

  7. Decomposition of PCBs in Oils Using Gamma Radiolysis A Treatability Study - Final Report

    SciTech Connect

    B. J. Mincher; R. E. Arbon

    1996-08-01

    Several legacy hydraulic oil waste streams contaminated with Aroclor 1260 and small amounts of Cesium-137 have been in storage at the Idaho National Engineering Laboratory (INEL) due to the lack of appropriate treatment facilities. The goal of this study was to demonstrate that polychlorinated biphenyls (PCBs) could be selectively decomposed in the oils. Removal of the PCB component to less than the 2 mg/L treatment standard should result in a waste oil that is not regulated by the Toxic Substances Control Act. Irradiation of the oils with high gamma-ray doses produces free electrons in the solution that react with PCBs. The reaction results in dechlorination of the PCBs to produce biphenyl. The gamma-ray source was spent reactor fuel stored in the Advanced Test Reactor canal at the INEL. A dry tube extends into the canal which allowed for positioning of samples in the proximity of the fuel. The gamma-ray dose rates at the samples varied from 10 to 30 kGy/h. This was measured using commercially available FWT-60 dosimeters. Irradiation of samples in a series of progressively increasing absorbed doses allowed the generation of rate constants used to predict absorbed doses necessary to meet the 2 mg/kg treatment standard. Three separate irradiation experiments were performed. The first irradiation used a maximum absorbed dose of 183 kGy. This experiment demonstrated that the PCB concentration decreased and allowed calculation of preliminary rate constants. The second irradiation used a maximum absorbed dose of 760 kGy. From this experiment, accurate rate constants were calculated, and the necessary absorbed dose to achieve the treatment standard was calculated. In the third irradiation of 2,242 kGy, all three waste streams were adequately decontaminated.

  8. Effects of Absorbing Aerosols on Accelerated Melting of Snowpack in the Tibetan-Himalayas Region

    NASA Technical Reports Server (NTRS)

    Lau, William K. M.

    2011-01-01

    The impacts of absorbing aerosol on melting of snowpack in the Hindu-Kush-Tibetan-Himalayas (HKTH) region are studied using NASA satellite and GEOS-5 GCM. Results from GCM experiments shows that a 8-10% in the rate of melting of snowpack over the western Himalayas and Tibetan Plateau can be attributed to the aerosol elevated-heat-pump (EHP) feedback effect (Lau et al. 2008), initiated by the absorption of solar radiation by absorbing aerosols accumulated over the Indo-Gangetic Plain and Himalayas foothills. On the other hand, deposition of black carbon on snow surface was estimated to give rise to a reduction in snow surface albedo of 2 - 5%, and an increased annual runoff of 9-24%. From case studies using satellite observations and re-analysis data, we find consistent signals of possible impacts of dust and black carbon aerosol in blackening snow surface, in accelerating spring melting of snowpack in the HKHT, and consequentially in influencing shifts in long-term Asian summer monsoon rainfall pattern.

  9. Fine-Resolution Voxel S Values for Constructing Absorbed Dose Distributions at Variable Voxel Size

    PubMed Central

    Dieudonné, Arnaud; Hobbs, Robert F.; Bolch, Wesley E.; Sgouros, George; Gardin, Isabelle

    2010-01-01

    This article presents a revised voxel S values (VSVs) approach for dosimetry in targeted radiotherapy, allowing dose calculation for any voxel size and shape of a given SPECT or PET dataset. This approach represents an update to the methodology presented in MIRD pamphlet no. 17. Methods VSVs were generated in soft tissue with a fine spatial sampling using the Monte Carlo (MC) code MCNPX for particle emissions of 9 radionuclides: 18F, 90Y, 99mTc, 111In, 123I, 131I, 177Lu, 186Re, and 201Tl. A specific resampling algorithm was developed to compute VSVs for desired voxel dimensions. The dose calculation was performed by convolution via a fast Hartley transform. The fine VSVs were calculated for cubic voxels of 0.5 mm for electrons and 1.0 mm for photons. Validation studies were done for 90Y and 131I VSV sets by comparing the revised VSV approach to direct MC simulations. The first comparison included 20 spheres with different voxel sizes (3.8–7.7 mm) and radii (4–64 voxels) and the second comparison a hepatic tumor with cubic voxels of 3.8 mm. MC simulations were done with MCNPX for both. The third comparison was performed on 2 clinical patients with the 3D-RD (3-Dimensional Radiobiologic Dosimetry) software using the EGSnrc (Electron Gamma Shower National Research Council Canada)-based MC implementation, assuming a homogeneous tissue-density distribution. Results For the sphere model study, the mean relative difference in the average absorbed dose was 0.20% ± 0.41% for 90Y and −0.36% ± 0.51% for 131I (n = 20). For the hepatic tumor, the difference in the average absorbed dose to tumor was 0.33% for 90Y and −0.61% for 131I and the difference in average absorbed dose to the liver was 0.25% for 90Y and −1.35% for 131I. The comparison with the 3D-RD software showed an average voxel-to-voxel dose ratio between 0.991 and 0.996. The calculation time was below 10 s with the VSV approach and 50 and 15 h with 3D-RD for the 2 clinical patients. Conclusion This new

  10. GRB 070125 and the environments of spectral-line poor afterglow absorbers

    NASA Astrophysics Data System (ADS)

    De Cia, A.; Starling, R. L. C.; Wiersema, K.; van der Horst, A. J.; Vreeswijk, P. M.; Björnsson, G.; de Ugarte Postigo, A.; Jakobsson, P.; Levan, A. J.; Rol, E.; Schulze, S.; Tanvir, N. R.

    2011-11-01

    GRB 070125 is among the most energetic bursts detected and the most extensively observed so far. Nevertheless, unresolved issues are still open in the literature on the physics of the afterglow and on the gamma-ray burst (GRB) environment. In particular, GRB 070125 was claimed to have exploded in a galactic halo environment, based on the uniqueness of the optical spectrum and the non-detection of an underlying host galaxy. In this work we collect all publicly available data and address these issues by modelling the near-infrared to X-ray spectral energy distribution (SED) and studying the high signal-to-noise ratio Very Large Telescope/FOcal Reducer/low dispersion Spectrograph afterglow spectrum in comparison with a larger sample of GRB absorbers. The SED reveals a synchrotron cooling break in the ultraviolet, low equivalent hydrogen column density and little reddening caused by a Large Magellanic Cloud type or Small Magellanic Cloud type extinction curve. From the weak Mg II absorption at z= 1.5477 in the spectrum, we derived log N(Mg II) = 12.96+0.13- 0.18 and upper limits on the ionic column density of several metals. These suggest that the GRB absorber is most likely a Lyman limit system with a 0.03 < Z < 1.3 Z⊙ metallicity. The comparison with other GRB absorbers places GRB 070125 at the low end of the absorption-line equivalent width distribution, confirming that weak spectral features and spectral-line poor absorbers are not so uncommon in afterglow spectra. Moreover, we show that the effect of photoionization on the gas surrounding the GRB, combined with a low N(H I) along a short segment of the line of sight within the host galaxy, can explain the lack of spectral features in GRB 070125. Finally, the non-detection of an underlying galaxy is consistent with a faint GRB host galaxy, well within the GRB host brightness distribution. Thus, the possibility that GRB 070125 is simply located in the outskirts of a gas-rich, massive star-forming region inside its

  11. Gamma-Ray Pulsar Revolution

    NASA Astrophysics Data System (ADS)

    Caraveo, Patrizia A.

    2014-08-01

    Isolated neutron stars (INSs) were the first sources identified in the field of high-energy gamma-ray astronomy. In the 1970s, only two sources had been identified, the Crab and Vela pulsars. However, although few in number, these objects were crucial in establishing the very concept of a gamma-ray source. Moreover, they opened up significant discovery space in both the theoretical and phenomenological fronts. The need to explain the copious gamma-ray emission of these pulsars led to breakthrough developments in understanding the structure and physics of neutron star (NS) magnetospheres. In parallel, the 20-year-long chase to understand the nature of Geminga unveiled the existence of a radio-quiet, gamma-ray-emitting INS, adding a new dimension to the INS family. We are living through an extraordinary time of discovery. The current generation of gamma-ray detectors has vastly increased the population of known gamma-ray-emitting NSs. The 100 mark was crossed in 2011, and we are now over 150. The gamma-ray-emitting NS population exhibits roughly equal numbers of radio-loud and radio-quiet young INSs, plus an astonishing, and unexpected, group of isolated and binary millisecond pulsars (MSPs). The number of MSPs is growing so rapidly that they are on their way to becoming the most numerous members of the family of gamma-ray-emitting NSs. Even as these findings have set the stage for a revolution in our understanding of gamma-ray-emitting NSs, long-term monitoring of the gamma-ray sky has revealed evidence of flux variability in the Crab Nebula as well as in the pulsed emission from PSR J2021+4026, challenging a four-decades-old, constant-emission paradigm. Now we know that both pulsars and their nebulae can, indeed, display variable emission.

  12. Interferon Gamma in Leishmaniasis

    PubMed Central

    Kima, Peter E.; Soong, Lynn

    2013-01-01

    Leishmaniasis is a complex disease that is caused by parasites of the Leishmania genus. Leishmania are further classified into several complexes, each of which can engage in distinct interactions with mammalian hosts resulting in differing disease presentations. It is therefore not unexpected that host immune responses to Leishmania are variable. The induction of interferon gamma (IFN-γ) and response to it in these infections has received considerable attention. In this review, we summarize our current understanding of some of the host responses during Leishmania infections that are regulated by IFN-γ. In addition, studies that explore the nature of parasite-derived molecular mediators that might affect the host response to IFN-γ are also discussed. PMID:23801993

  13. Interferon gamma in leishmaniasis.

    PubMed

    Kima, Peter E; Soong, Lynn

    2013-01-01

    Leishmaniasis is a complex disease that is caused by parasites of the Leishmania genus. Leishmania are further classified into several complexes, each of which can engage in distinct interactions with mammalian hosts resulting in differing disease presentations. It is therefore not unexpected that host immune responses to Leishmania are variable. The induction of interferon gamma (IFN-γ) and response to it in these infections has received considerable attention. In this review, we summarize our current understanding of some of the host responses during Leishmania infections that are regulated by IFN-γ. In addition, studies that explore the nature of parasite-derived molecular mediators that might affect the host response to IFN-γ are also discussed.

  14. Changing the gamma knife.

    PubMed

    Ganz, Jeremy C

    2014-01-01

    The first Gamma Knife used helmets containing collimators of different diameters that increase the flexibility of the treatment. Changing these helmets was time-consuming and tedious. The original model that was introduced into the United States was the U model where the patient was inserted into the machine inward and upward, using hydraulics. A new simpler machine was devised called the B model where the patient simply moved in and out, but there was still the problem of changing helmets. Then, the C model was introduced, with a robot called the automatic positioning system that permitted the patient’s position to be moved automatically. However, the helmets still had to be changed when collimators of different sizes were required. Finally, an entirely redesigned model called Perfexion was introduced where there were no helmets and the patient once placed in the machine would be treated completely following a single pressure on a button. PMID:25376576

  15. Gamma Ray Bursts - Observations

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Cannizzo, J. K.

    2010-01-01

    We are in an exciting period of discovery for gamma-ray bursts. The Swift observatory is detecting 100 bursts per year, providing arcsecond localizations and sensitive observations of the prompt and afterglow emission. The Fermi observatory is observing 250 bursts per year with its medium-energy GRB instrument and about 10 bursts per year with its high-energy LAT instrument. In addition, rapid-response telescopes on the ground are providing new capabilities to study optical emission during the prompt phase and spectral signatures of the host galaxies. The combined data set is enabling great advances in our understanding of GRBs including afterglow physics, short burst origin, and high energy emission.

  16. Sensitometry of the response of a new radiochromic film dosimeter to gamma radiation and electron beams

    NASA Astrophysics Data System (ADS)

    McLaughlin, W. L.; Yun-Dong, Chen; Soares, C. G.; Miller, A.; Van Dyk, G.; Lewis, D. F.

    1991-04-01

    A new radiation-sensitive imaging material, called GafChromic™ Dosimetry Media, offers advances in high-dose radiation dosimetry and high-resolution radiography for gamma radiation and electrons. The potential uses in radiation processing, radiation sterilization of medical devices, population control of insects by irradiation, food irradiation, blood irradiation for organ-transplant immuno-suppression, clinical radiography, and industrial radiography have led to the present sensitometric study over the breadth of the wide dynamic range of this new routine detector and imaging material, namely, absorbed doses from 10 Gy to 5 × 10 4 Gy. The thin-coated film is colorless before irradiation, and registers a deep-blue image upon irradiation, with two absorption bands at about 650 nm (major band) and 600 nm (minor band). The response to electrons, in terms of increase in absorbance per unit absorbed dose, is the same as that to gamma radiation within the estimated uncertainty of the measurements (± 5%, 95% confidence level). The spatial resolving power is > 1200 lines/mm. After the first 24 hours, the image is stable over many months (within ± 5% in absorbance), however, the system should be irradiated and analyzed at approximately the temperatures used during calibration, because of temperature dependence during irradiation and readout, and temperatures greater than 55°C should be avoided.

  17. Reassessment of gamma-ray doses in Hiroshima and Nagasaki.

    PubMed

    Maruyama, T; Kumamoto, Y; Noda, Y

    1991-03-01

    Reassessment of gamma-ray doses from the atomic bombs in Hiroshima and Nagasaki has been carried out with the thermoluminescent measurements of bricks and decorative tiles which were collected from the buildings that remain as they were at the time of the explosions. The thermoluminescent measurements were performed using a dating technique generally used in archaeology. Annual background dose rates from natural radionuclides in the brick and tile samples and from environmental radiations around the samples were determined with commercially available thermoluminescent detectors. The resultant gamma-ray doses in Hiroshima and Nagasaki are given as a function of distance from the hypocenters and are compared with the DS86 (Dosimetry System 1986) and the T65D (Tentative 1965 Dose).

  18. Gamma radiolytic degradation of naphthalene in aqueous solution

    NASA Astrophysics Data System (ADS)

    Chu, Libing; Yu, Shaoqing; Wang, Jianlong

    2016-06-01

    The decomposition of naphthalene in aqueous solution was studied using gamma irradiation combined with both H2O2 and TiO2 nanoparticles. Gamma irradiation led to a complete degradation of naphthalene and a partial mineralization. With initial concentration of 5-32 mg/L, more than 98% of naphthalene was removed and TOC reduction reached 28-31% at an absorbed dose of 3.0 kGy. The degradation of naphthalene was faster at neutral pH and the initial degradation rate increased with increasing the initial concentration of naphthalene. Addition of H2O2 and TiO2 nanoparticles all enhanced the degradation and mineralization of naphthalene. TOC removal efficiency increased from 28% (irradiation alone) to 35% with addition of H2O2 (40 mg/L), and to 48% with addition of TiO2 (0.8 g/L). The degradation of naphthalene in aqueous solution by gamma irradiation was mainly through the oxidation by ·OH radicals. The intermediate naphthol and carboxylic acids such as formic acid and oxalic acid were identified by LC-MS and IC.

  19. Gamma ray astrophysics, the extragalactic background light, and new physics

    SciTech Connect

    Serpico, Pasquale D.; /Fermilab

    2008-09-01

    Very high energy gamma-rays are expected to be absorbed by the extragalactic background light over cosmological distances via the process of electron-positron pair production. However, recent observations of cosmologically distant emitters by ground based gamma-ray telescopes might be indicative of a higher-than-expected degree of transparency of the universe. One mechanism to explain this observation is the oscillation between photons and axion-like-particles (ALPs). Here we explore this possibility, focusing on photon-ALP conversion in the magnetic fields in and round gamma-ray sources and in the magnetic field of the Milky Way, where some fraction of the ALP flux is converted back into photons. We show that this mechanism can be efficient in allowed regions of the ALP parameter space, as well as in typical configurations of the Galactic Magnetic Field. As case example, we consider the spectrum observed from a HESS source. We also discuss features of this scenario which could be used to distinguish it from standard or other exotic models.

  20. Matter-antimatter gigaelectron volt gamma ray laser rocket propulsion

    NASA Astrophysics Data System (ADS)

    Winterberg, F.

    2012-12-01

    It is shown that the idea of a photon rocket through the complete annihilation of matter with antimatter, first proposed by Sänger, is not a utopian scheme as it is widely believed. Its feasibility appears to be possible by the radiative collapse of a relativistic high current pinch discharge in a hydrogen-antihydrogen ambiplasma down to a radius determined by Heisenberg's uncertainty principle. Through this collapse to ultrahigh densities the proton-antiproton pairs in the center of the pinch can become the upper gigaelectron volt laser level for the transition into a coherent gamma ray beam by proton-antiproton annihilation, with the magnetic field of the collapsed pinch discharge absorbing the recoil momentum of the beam and transmitting it by the Moessbauer effect to the spacecraft. The gamma ray laser beam is launched as a photon avalanche from one end of the pinch discharge channel. Because of the enormous technical problems to produce and store large amounts of anti-matter, such a propulsion concept may find its first realization in small unmanned space probes to explore nearby solar systems. The laboratory demonstration of a gigaelectron volt gamma ray laser by comparison requiring small amounts of anti-matter may be much closer.