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Sample records for gamma dalam dosis

  1. The Diffusion Ordered Spectroscopy (DOSY) Pulse Sequence and Defence Applications

    DTIC Science & Technology

    2008-05-01

    The Diffusion Ordered SpectroscopY ( DOSY ) Pulse Sequence and Defence Applications Simon P. B. Ovenden and David J. Bourne...discuss all aspects of the DOSY two dimensional NMR experiment, including setting up the experiment, the collection of raw data, and the data processing...required. Details of the DOSY experiment are explained through data collected on a variety of samples involving several chemical classes. At the end

  2. Applications of Diffusion Ordered Spectroscopy (DOSY-NMR)

    USDA-ARS?s Scientific Manuscript database

    Diffusion-ordered NMR (DOSY-NMR) is a powerful, but under-utilized, technique for the investigation of mixtures based on translational diffusion rates. DOSY spectra allow for determination by NMR of components that may differ in molecular weight, geometry or complexation. Typical applications coul...

  3. (19) F DOSY diffusion-NMR spectroscopy of fluoropolymers.

    PubMed

    Xu, Chenglong; Wan, Yingbo; Chen, Dongxue; Gao, Chun; Yin, Hongnan; Fetherston, Daniel; Kupce, Eriks; Lopez, Gerald; Ameduri, Bruno; Twum, Eric B; Wyzgoski, Faith J; Li, Xiaohong; McCord, Elizabeth F; Rinaldi, Peter L

    2017-05-01

    A new pulse sequence for obtaining (19) F detected DOSY (diffusion ordered spectroscopy) spectra of fluorinated molecules is presented and used to study fluoropolymers based on vinylidene fluoride and chlorotrifluoroethylene. The performance of (19) F DOSY NMR experiments (and in general any type of NMR experiment) on fluoropolymers creates some unique complications that very often prevent detection of important signals. Factors that create these complications include: (1) the presence of many scalar couplings among (1) H, (19) F and (13) C; (2) the large magnitudes of many (19) F homonuclear couplings (especially (2) JFF ); (3) the large (19) F chemical shift range; and (4) the low solubility of these materials (which requires that experiments be performed at high temperatures). A systematic study of the various methods for collecting DOSY NMR data, and the adaptation of these methods to obtain (19) F detected DOSY data, has been performed using a mixture of low molecular weight, fluorinated model compounds. The best pulse sequences and optimal experimental conditions have been determined for obtaining (19) F DOSY spectra. The optimum pulse sequences for acquiring (19) F DOSY NMR data have been determined for various circumstances taking into account the spectral dispersion, number and magnitude of couplings present, and experimental temperature. Pulse sequences and experimental parameters for optimizing these experiments for the study of fluoropolymers have been studied. Copyright © 2016 John Wiley & Sons, Ltd.

  4. Studies on supramolecular gel formation using DOSY NMR.

    PubMed

    Nonappa; Šaman, David; Kolehmainen, Erkki

    2015-04-01

    Herein, we present the results obtained from our studies on supramolecular self-assembly and molecular mobility of low-molecular-weight gelators (LMWGs) in organic solvents using pulsed field gradient (PFG) diffusion ordered spectroscopy (DOSY) NMR. A series of concentration-dependent DOSY NMR experiments were performed on selected LMWGs to determine the critical gelation concentration (CGC) as well as to understand the behaviour of the gelator molecules in the gel state. In addition, variable-temperature DOSY NMR experiments were performed to determine the gel-to-sol transition. The PFG NMR experiments performed as a function of gradient strength were further analyzed using monoexponential DOSY processing, and the results were compared with the automated Bayesian DOSY transformation to obtain 2D plots. Our results provide useful information on the stepwise self-assembly of small molecules leading to gelation. We believe that the results obtained from these experiments are applicable in determining the CGC and gel melting temperatures of supramolecular gels.

  5. Simplifying DOSY spectra with selective TOCSY edited preparation

    NASA Astrophysics Data System (ADS)

    Bradley, Scott A.; Krishnamurthy, Krish; Hu, Haitao

    2005-01-01

    Diffusion-ordered NMR spectroscopy, while quite powerful, is limited by its inability to resolve signals that are severely overlapped in the proton spectrum. We present here a DOSY experiment that uses selective TOCSY as an editing/preparation period. With this method, well-resolved signals of the analytes are selectively excited and the magnetization subsequently transferred by isotropic mixing to resonances buried in the matrix background, which are then resolved by the ensuing DOSY sequence. Key to the success of our proposed method is the incorporation of a highly effective zero-quantum filter into the selective TOCSY preparation period, which prevents zero-quantum coherence from being carried into the DOSY part of the pulse sequence. Further improvement in spectral resolution can be obtained by expanding the proposed experiment into a 3D sequence and utilizing the homonuclear decoupling feature of the BASHD-TOCSY technique. Both pulse sequences were found to greatly simplify the DOSY spectrum of a 'dirty' sucrose/raffinose mixture, as the complex matrix background is no longer present to obscure or overlap with the signals of interests. Furthermore, complete resolution of the relevant signals was achieved with the 3D sequence.

  6. The DOSIS and DOSIS 3D Experiments onboard the International Space Station - Results from the Active DOSTEL Instruments

    NASA Astrophysics Data System (ADS)

    Burmeister, Soenke; Berger, Thomas; Reitz, Guenther; Beaujean, Rudolf; Boehme, Matthias; Haumann, Lutz; Labrenz, Johannes; Kortmann, Onno

    2012-07-01

    Besides the effects of the microgravity environment, and the psychological and psychosocial problems experienced in confined spaces, radiation is the main health detriment for long duration human space missions. The radiation environment encountered in space differs in nature from that on earth, consisting mostly of high energetic ions from protons up to iron, resulting in radiation levels far exceeding the ones present on earth for occupational radiation workers. Accurate knowledge of the physical characteristics of the space radiation field in dependence on the solar activity, the orbital parameters and the different shielding configurations of the International Space Station ISS is therefore needed. For the investigation of the spatial and temporal distribution of the radiation field inside the European COLUMBUS module the experiment DOSIS (Dose Distribution Inside the ISS) under the lead of DLR was launched on July 15th 2009 with STS-127 to the ISS. The experimental package was transferred from the Space Shuttle into COLUMBUS on July 18th. It consists of a combination of passive detector packages (PDP) distributed at 11 locations inside the European Columbus Laboratory and two active radiation detectors (DOSTELs) with a DDPU (DOSTEL Data and Power Unit) in a nomex pouch (DOSIS MAIN BOX) mounted at a fixed location beneath the European Physiology Module rack (EPM) inside COLUMBUS. The DOSTELs measured during the lowest solar minimum conditions in the space age from July 18th 2009 to June 16th 2011. In July 2011 the active hardware was transferred to ground for refurbishment and preparation for the DOSIS-3D experiment. The hardware will be launched with the Soyuz 30S flight to the ISS on May 15th 2012 and activated approximately ten days later. Data will be transferred from the DOSTEL units to ground via the EPM rack which is activated approximately every four weeks for this action. First Results for the active DOSIS-3D measurements such as count rate profiles

  7. Long term dose monitoring onboard the European Columbus module of the International Space Station (ISS) in the frame of the DOSIS and DOSIS 3D project

    NASA Astrophysics Data System (ADS)

    Berger, Thomas

    The radiation environment encountered in space differs in nature from that on earth, consisting mostly of high energetic ions from protons up to iron, resulting in radiation levels far exceeding the ones present on earth for occupational radiation workers. Accurate knowledge of the physical characteristics of the space radiation field in dependence on the solar activity, the orbital parameters and the different shielding configurations of the International Space Station (ISS) is therefore needed. For the investigation of the spatial and temporal distribution of the radiation field inside the European Columbus module the experiment “Dose Distribution Inside the ISS” (DOSIS), under the project and science lead of the German Aerospace Center (DLR), was launched on July 15th 2009 with STS-127 to the ISS. The DOSIS experiment consists of a combination of “Passive Detector Packages” (PDP) distributed at eleven locations inside Columbus for the measurement of the spatial variation of the radiation field and two active Dosimetry Telescopes (DOSTELs) with a Data and Power Unit (DDPU) in a dedicated nomex pouch mounted at a fixed location beneath the European Physiology Module rack (EPM) for the measurement of the temporal variation of the radiation field parameters. The DOSIS experiment suite measured during the lowest solar minimum conditions in the space age from July 2009 to June 2011. In July 2011 the active hardware was transferred to ground for refurbishment and preparation for the follow up DOSIS 3D experiment. The hardware for DOSIS 3D was launched with Soyuz 30S to the ISS on May 15th 2012. The PDPs are replaced with each even number Soyuz flight starting with Soyuz 30S. Data from the active detectors is transferred to ground via the EPM rack which is activated once a month for this action. The presentation will give an overview of the DOSIS and DOSIS 3D experiment and focus on the results from the passive radiation detectors from the DOSIS 3D experiment

  8. Design and Testing of the Degree of Shoulder Involvement in Sports (DOSIS) Scale.

    PubMed

    Blonna, Davide; Bellato, Enrico; Bonasia, Davide Edoardo; Canata, Gian Luigi; Rossi, Roberto; Marmotti, Antonio; Castoldi, Filippo

    2015-10-01

    For athletes affected by shoulder problems, the most important expectation is to resume sporting activities. The ability to return to sport is related to several parameters, including the type and level of sport played. By focusing on these parameters, the Degree of Shoulder Involvement in Sports (DOSIS) scale allows for a better assessment of the involvement of the shoulder in sports. To design the DOSIS scale and test its psychometric features. Cohort study; Level of evidence, 3. The DOSIS scale was developed as a patient self-administered scale by the Sport Committee of SIGASCOT (Società Italiana del Ginocchio Artroscopia Sport Cartilagine Tecnologie Ortopediche) to score sports activity based on 3 parameters: (1) type of sport, (2) frequency with which the sport is played, and (3) level at which the sport is played. In a subsequent phase, the psychometric features of the DOSIS scale were measured in a cohort of 85 patients who were affected by recurrent anterior shoulder instability and who underwent an open Bristow-Latarjet procedure or an arthroscopic Bankart repair. The content validity, criterion validity, construct validity, responsiveness, and test-retest reliability were measured and compared with the psychometric features of the Tegner activity scale. Neither the DOSIS nor the Tegner activity scale showed floor or ceiling effects, but the DOSIS scale had a different distribution of scores, with a tendency toward a higher percentage of patients with high scores. The test-retest reliability analysis of the DOSIS scale revealed excellent intraobserver reliability (intraclass correlation coefficient = 0.96). Regarding the construct validity, 3 of the 4 hypotheses that we tested were significant. The DOSIS scale showed good criterion validity when compared with the Tegner activity scale (ρ = 0.3, P = .003), and the effect size between the preoperative and postoperative DOSIS scale was 1.1. The DOSIS scale showed acceptable psychometric features and seems

  9. DOSY of sample-limited mixtures: comparison of cold, nano and conventional probes.

    PubMed

    Bradley, Scott A; Paschal, Jonathan; Kulanthaivel, Palaniappan

    2005-01-01

    The DOSY analysis of dilute mixtures can be a challenge because a high signal-to-noise ratio is required for the best DOSY results. The sensitivity increase gained from new probe technologies (e.g. cold and nano probes) could enable one to acquire good DOSY spectra on sample amounts too low for conventional probes. In this article, we investigated the performance of cold and nano probes for qualitative DOSY analysis of concentrated and sample-limited mixtures, and compared the results with those of the conventional probe. We first measured the fluid flow for each probe. All three probes exhibited only relatively small levels of flow; consequently, a double-stimulated echo pulse sequence was not employed in the subsequent DOSY experiments. This decision was based on three facts: (1) flow-induced phase distortions were not observed, (2) our intentions are only to perform qualitative mixture analysis, and (3) discarding 50% of the already limited signal cannot be afforded. Although the cold and nano probes produced DOSY results for the concentrated mixture that were inferior to the conventional probe, the increase in the signal-to-noise ratio observed with these probes proved to be advantageous for the dilute three-component mixture. Furthermore, the cold probe showed slightly superior performance over the nano probe; thus, we conclude that among the probes examined the cold probe is best suited for qualitative DOSY analysis of sample-limited mixtures.

  10. DOSIS & DOSIS 3D: long-term dose monitoring onboard the Columbus Laboratory of the International Space Station (ISS)

    NASA Astrophysics Data System (ADS)

    Berger, Thomas; Przybyla, Bartos; Matthiä, Daniel; Reitz, Günther; Burmeister, Sönke; Labrenz, Johannes; Bilski, Pawel; Horwacik, Tomasz; Twardak, Anna; Hajek, Michael; Fugger, Manfred; Hofstätter, Christina; Sihver, Lembit; Palfalvi, Jozsef K.; Szabo, Julianna; Stradi, Andrea; Ambrozova, Iva; Kubancak, Jan; Brabcova, Katerina Pachnerova; Vanhavere, Filip; Cauwels, Vanessa; Van Hoey, Olivier; Schoonjans, Werner; Parisi, Alessio; Gaza, Ramona; Semones, Edward; Yukihara, Eduardo G.; Benton, Eric R.; Doull, Brandon A.; Uchihori, Yukio; Kodaira, Satoshi; Kitamura, Hisashi; Boehme, Matthias

    2016-11-01

    The radiation environment encountered in space differs in nature from that on Earth, consisting mostly of highly energetic ions from protons up to iron, resulting in radiation levels far exceeding the ones present on Earth for occupational radiation workers. Since the beginning of the space era, the radiation exposure during space missions has been monitored with various active and passive radiation instruments. Also onboard the International Space Station (ISS), a number of area monitoring devices provide data related to the spatial and temporal variation of the radiation field in and outside the ISS. The aim of the DOSIS (2009-2011) and the DOSIS 3D (2012-ongoing) experiments was and is to measure the radiation environment within the European Columbus Laboratory of the ISS. These measurements are, on the one hand, performed with passive radiation detectors mounted at 11 locations within Columbus for the determination of the spatial distribution of the radiation field parameters and, on the other, with two active radiation detectors mounted at a fixed position inside Columbus for the determination of the temporal variation of the radiation field parameters. Data measured with passive radiation detectors showed that the absorbed dose values inside the Columbus Laboratory follow a pattern, based on the local shielding configuration of the radiation detectors, with minimum dose values observed in the year 2010 of 195-270 μGy/day and maximum values observed in the year 2012 with values ranging from 260 to 360 μGy/day. The absorbed dose is modulated by (a) the variation in solar activity and (b) the changes in ISS altitude.

  11. STD-DOSY: A new NMR method to analyze multi-component enzyme/substrate systems

    NASA Astrophysics Data System (ADS)

    Kramer, Markus; Kleinpeter, Erich

    2010-02-01

    A new approach to analyze multi-component Saturation Transfer Difference (STD) NMR spectra by combining the STD and the DOSY experiment is proposed. The resulting pulse sequence was successfully used to simplify an exemplary multi-component protein/substrate system by means of standard DOSY processing methods. Furthermore, the same experiment could be applied to calculate the ratio of saturated substrate molecules and its saturation rate in the case of competitive interactions. This ratio depends on the strength of this interaction between the substrates and the protein, so that this kind of information could be extracted from the results of our experiment.

  12. Study of the Effect of Iron Loaded with B4C on the Total Gamma Doses Emitted from Laminated Shield

    NASA Astrophysics Data System (ADS)

    Makarious, A. S.; Maayouf, R. M. A.; Megahid, R. M.; El-Sayed Abdo, A.

    In this work a comparative study of the effect of iron loaded with B4C on the suppression of gamma-rays in a laminated shield of water, iron and either ordinary or limenite concrete have been carried out. It was found that B4C loaded with iron has a remarkable effect on the suppression of gamma doses all through the laminated shield. The suppression is more pronounced in the concrete layer. It was also found that the decrease of gamma doses in ilmenite concrete is 1.7 that one for ordinary concrete.Translated AbstractUntersuchung des Einflusses von mit B4C angereichertem Eisen auf die Gesamt-Gamma-Dosis aus einem laminierten SchildDer Effekt von mit B4C angereichertem Eisen auf die Abschirmung von Gamma-Strahlen durch einen laminierten Schild aus Wasser, Eisen und entweder gewöhnlichem oder Ilmenitebeton wird vergleichend untersucht. Es erweist sich ein bemerkenswerter Effekt des angereicherten Eisens auf die Abschwächung der Gamma-Dosis im gesamten Schild. Sie ist in der Betonschicht am ausgeprägtesten. Die Abnahme der Gamma-Dosis in Ilmenitebeton ist etwa 1,7fach der in gewöhnlichem Beton.

  13. The usefulness of 2D DOSY and 3D DOSY-COSY 1H NMR for mixture analysis: application to genuine and fake formulations of sildenafil (Viagra).

    PubMed

    Trefi, Saleh; Gilard, Véronique; Balayssac, Stéphane; Malet-Martino, Myriam; Martino, Robert

    2009-12-01

    Two-dimensional diffusion ordered spectroscopy (DOSY) (1)H NMR is proposed to analyze drugs that are complex mixtures in order to discriminate genuine from fake formulations. The method was applied to the analysis of 17 formulations of sildenafil, one being genuine Viagra and the others illegally manufactured formulations of this drug coming from India, Syria and China. It enabled (i) distinguishing imitations or counterfeit from the authentic formulation, (ii) detecting the presence of sildenafil or adulterants, (iii) gaining information on the formulation process by detection of various excipients, thus giving a precise and global 'signature' of the manufacturer. Even though some samples are slightly overdosed, the quality of products manufactured in India and Syria was better than that of Chinese formulations which were adulterated with vardenafil and homosildenafil. This study also presents a three-dimensional DOSY-COSY (1)H NMR experiment that provides both virtual separation and structural information.

  14. Development Activities Locator and Assessment Method (DALAM)

    DTIC Science & Technology

    2013-11-01

    CENTER FOR ARMY ANALYSIS 6001 GOETHALS ROAD FORT BELVOIR, VA 22060-5230 CAA-2012049 DEVELOPMENT ACTIVITIES LOCATOR AND ASSESSMENT METHOD...CONTRACT NUMBER Development Activities Locator and Assessment Method (DALAM) 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d...the problem may be more fundamental, in that the design of our projects is flawed. This study, Development Activities Locator and Assessment Method

  15. Long term dose monitoring onboard the European Columbus module of the international space station (ISS) in the frame of DOSIS and DOSIS 3D project - results from the active instruments

    NASA Astrophysics Data System (ADS)

    Burmeister, Soenke; Berger, Thomas; Reitz, Guenther; Boehme, Matthias; Haumann, Lutz; Labrenz, Johannes

    Besides the effects of the microgravity environment, and the psychological and psychosocial problems encountered in confined spaces, radiation is the main health detriment for long duration human space missions. The radiation environment encountered in space differs in nature from that on earth, consisting mostly of high energetic ions from protons up to iron, resulting in radiation levels far exceeding the ones encountered on earth for occupational radiation workers. Accurate knowledge of the physical characteristics of the space radiation field in dependence on the solar activity, the orbital parameters and the different shielding configurations of the International Space Station ISS is therefore needed. For the investigation of the spatial and temporal distribution of the radiation field inside the European COLUMBUS module the experiment DOSIS (Dose Distribution Inside the ISS) under the lead of DLR has been launched on July 15 (th) 2009 with STS-127 to the ISS. The experimental package was transferred from the Space Shuttle into COLUMBUS on July 18 (th) . It consists of a combination of passive detector packages (PDP) distributed at 11 locations inside the European Columbus Laboratory and two active radiation detectors (Dosimetry Telescopes = DOSTELs) with a DDPU (DOSTEL Data and Power Unit) in a Nomex pouch (DOSIS MAIN BOX) mounted at a fixed location beneath the European Physiology Module rack (EPM) inside COLUMBUS. The active components of the DOSIS experiment were operational from July 18 (th) 2009 to June 16 (th) 2011. After refurbishment the hardware has been reactivated on May 15 (th) 2012 as active part of the DOSIS 3D experiment and provides continuous data since this activation. The presentation will focus on the latest results from the two DOSTEL instruments as absorbed dose, dose equivalent and the related LET spectra gathered within the DOSIS (2009 - 2011) and DOSIS 3D (2012 - 2014) experiment. The CAU contributions to DOSIS and DOSIS 3D are

  16. Characterization of heroin samples by 1H NMR and 2D DOSY 1H NMR.

    PubMed

    Balayssac, Stéphane; Retailleau, Emmanuel; Bertrand, Geneviève; Escot, Marie-Pierre; Martino, Robert; Malet-Martino, Myriam; Gilard, Véronique

    2014-01-01

    Twenty-four samples of heroin from different illicit drug seizures were analyzed using proton Nuclear Magnetic Resonance ((1)H NMR) and two-dimensional diffusion-ordered spectroscopy (2D DOSY) (1)H NMR. A careful assignment and quantification of (1)H signals enabled a comprehensive characterization of the substances present in the samples investigated: heroin, its main related impurities (6-acetylmorphine, acetylcodeine, morphine, noscapine and papaverine) and cutting agents (caffeine and acetaminophen in nearly all samples as well as lactose, lidocaine, mannitol, piracetam in one sample only), and hence to establish their spectral signatures. The good agreement between the amounts of heroin, noscapine, caffeine and acetaminophen determined by (1)H NMR and gas chromatography, the reference method in forensic laboratories, demonstrates the validity of the (1)H NMR technique. In this paper, 2D DOSY (1)H NMR offers a new approach for a whole characterization of the various components of these complex mixtures.

  17. Gamma Knife

    MedlinePlus

    ... equipment? How is safety ensured? What is this equipment used for? The Gamma Knife® and its associated ... in size. top of page How does the equipment work? The Gamma Knife® utilizes a technique called ...

  18. The Degree of Shoulder Involvement in Sports (DOSIS) scale is a valid and responsive instrumentation for shoulder assessment in patients after surgery for anterior instability.

    PubMed

    Vascellari, Alberto; Ramponi, Carlo; Venturin, Davide; Ben, Giulia; Blonna, Davide; Coletti, Nicolò

    2017-07-18

    The purpose of this study was to evaluate validity and responsiveness of the Degree of Shoulder Involvement in Sport (DOSIS) scale. A web-based survey was developed to test the construct validity of the DOSIS scale. Fifty-three patients with a median age of 33 years (range 17-59) were included in the study. Convergent validity was evaluated by external correlation (Spearman's rank correlation coefficient, r) of the DOSIS with the Brophy-Marx and Tegner activity scales, the Western Ontario shoulder instability index (WOSI), the Simple Shoulder Test (SST), and the Short-Form 36 (SF-36). Responsiveness was analysed by relative efficiency calculation of the DOSIS versus the Brophy-Marx and Tegner activity scales. The DOSIS showed strong correlation with the Brophy-Marx and Tegner activity scales, a moderate correlation with the WOSI and SST scores, and a moderate correlation with the physical functioning, role physical and role emotional subscores of the SF-36. The distribution of the DOSIS scores had no serious ceiling or floor effects. The DOSIS demonstrated lesser responsiveness when compared to the Brophy-Marx and Tegner activity scales. The DOSIS showed an adequate validity and responsiveness. The clinical relevance of this study is that the DOSIS scale can be used for sport-specific shoulder assessment in patients after surgery for anterior instability. III.

  19. DOSIS & DOSIS 3D: radiation measurements with the DOSTEL instruments onboard the Columbus Laboratory of the ISS in the years 2009-2016

    NASA Astrophysics Data System (ADS)

    Berger, Thomas; Burmeister, Sönke; Matthiä, Daniel; Przybyla, Bartos; Reitz, Günther; Bilski, Pawel; Hajek, Michael; Sihver, Lembit; Szabo, Julianna; Ambrozova, Iva; Vanhavere, Filip; Gaza, Ramona; Semones, Edward; Yukihara, Eduardo G.; Benton, Eric R.; Uchihori, Yukio; Kodaira, Satoshi; Kitamura, Hisashi; Boehme, Matthias

    2017-03-01

    The natural radiation environment in Low Earth Orbit (LEO) differs significantly in composition and energy from that found on Earth. The space radiation field consists of high energetic protons and heavier ions from Galactic Cosmic Radiation (GCR), as well as of protons and electrons trapped in the Earth's radiation belts (Van Allen belts). Protons and some heavier particles ejected in occasional Solar Particle Events (SPEs) might in addition contribute to the radiation exposure in LEO. All sources of radiation are modulated by the solar cycle. During solar maximum conditions SPEs occur more frequently with higher particle intensities. Since the radiation exposure in LEO exceeds exposure limits for radiation workers on Earth, the radiation exposure in space has been recognized as a main health concern for humans in space missions from the beginning of the space age on. Monitoring of the radiation environment is therefore an inevitable task in human spaceflight. Since mission profiles are always different and each spacecraft provides different shielding distributions, modifying the radiation environment measurements needs to be done for each mission. The experiments "Dose Distribution within the ISS (DOSIS)" (2009-2011) and "Dose Distribution within the ISS 3D (DOSIS 3D)" (2012-onwards) onboard the Columbus Laboratory of the International Space Station (ISS) use a detector suite consisting of two silicon detector telescopes (DOSimetry TELescope = DOSTEL) and passive radiation detector packages (PDP) and are designed for the determination of the temporal and spatial variation of the radiation environment. With the DOSTEL instruments' changes of the radiation composition and the related exposure levels in dependence of the solar cycle, the altitude of the ISS and the influence of attitude changes of the ISS during Space Shuttle dockings inside the Columbus Laboratory have been monitored. The absorbed doses measured at the end of May 2016 reached up to 286

  20. DOSY-NMR and raman investigations on the self-aggregation and cyclodextrin complexation of vanillin.

    PubMed

    Ferrazza, Ruggero; Rossi, Barbara; Guella, Graziano

    2014-06-26

    Vanillin (4-hydroxy-3-methoxybenzaldehyde) is a phenolic aldehyde with limited solubility in water; in this work, we investigate its self-aggregation, as well as its complexation equilibria with β-cyclodextrin by using nuclear magnetic resonance (NMR) and vibrational spectroscopy. In particular, diffusion-ordered NMR (DOSY) measurements allowing to detect diffusional changes caused by aggregation/inclusion phenomena lead to a reliable estimate of the equilibrium constants of these processes, while Raman spectroscopy was used to further characterize some structural details of vanillin self-aggregates and inclusion complexes. Although the self-association binding constant of vanillin in water was found to be low (K(a) ∼10), dimeric species are not negligible within the investigated range of concentration (3-65 mM); on the other hand, formation of β-cyclodextrin self-aggregates was not detected by DOSY measurements on aqueous solutions of β-cyclodextrin at different concentrations (2-12 mM). Finally, the binding of vanillin with β-cyclodextrin, as measured by the DOSY technique within a narrow range of concentrations (2-15 mM) by assuming the existence of only the monomeric 1:1 vanillin/β-CD complex, was about an order of magnitude higher (K(c) ∼ 90) than self-aggregation. However, the value of the equilibrium constant for this complexation was found to be significantly affected by the analytical concentrations of the host and guest system, thus indicating that K(c) is an "apparent" equilibrium constant.

  1. Controlled trial of D-penicillamine with low dosis in the treatment of chronic liver diseases.

    PubMed

    Nakano, H; Ohnishi, S; Sugiyama, T; Miyamura, M; Imura, H; Yamamoto, Y; Ito, K

    1980-01-01

    Controlled trial of D-penicillamine was carried out with low dosis in 10 patients with chronic persistent hepatitis, 11 patients with chronic aggressive hepatitis and 7 patients with liver cirrhosis. After 6 weeks and 6 months treatment mean values of transaminases improved in patients with chronic persistent hepatitis. The mean serum transaminases levels of the patients with chronic aggressive hepatitis were statistically decreased after 6 weeks treatment but not significantly lower after 6 months treatment than on entry. D-penicillamine is not effective for the treatment of patients with liver cirrhosis. Eight of 36 patients treated were withdrawn from the trial because of adverse drug toxicity side effects.

  2. Quality control and assurance for validation of DOS/I measurements

    NASA Astrophysics Data System (ADS)

    Cerussi, Albert; Durkin, Amanda; Kwong, Richard; Quang, Timothy; Hill, Brian; Tromberg, Bruce J.; MacKinnon, Nick; Mantulin, William W.

    2010-02-01

    Ongoing multi-center clinical trials are crucial for Biophotonics to gain acceptance in medical imaging. In these trials, quality control (QC) and assurance (QA) are key to success and provide "data insurance". Quality control and assurance deal with standardization, validation, and compliance of procedures, materials and instrumentation. Specifically, QC/QA involves systematic assessment of testing materials, instrumentation performance, standard operating procedures, data logging, analysis, and reporting. QC and QA are important for FDA accreditation and acceptance by the clinical community. Our Biophotonics research in the Network for Translational Research in Optical Imaging (NTROI) program for breast cancer characterization focuses on QA/QC issues primarily related to the broadband Diffuse Optical Spectroscopy and Imaging (DOS/I) instrumentation, because this is an emerging technology with limited standardized QC/QA in place. In the multi-center trial environment, we implement QA/QC procedures: 1. Standardize and validate calibration standards and procedures. (DOS/I technology requires both frequency domain and spectral calibration procedures using tissue simulating phantoms and reflectance standards, respectively.) 2. Standardize and validate data acquisition, processing and visualization (optimize instrument software-EZDOS; centralize data processing) 3. Monitor, catalog and maintain instrument performance (document performance; modularize maintenance; integrate new technology) 4. Standardize and coordinate trial data entry (from individual sites) into centralized database 5. Monitor, audit and communicate all research procedures (database, teleconferences, training sessions) between participants ensuring "calibration". This manuscript describes our ongoing efforts, successes and challenges implementing these strategies.

  3. Resolution of a nonionic surfactant oligomeric mixture by means of DOSY with inverse micelle assistance.

    PubMed

    Asaro, Fioretta; Savko, Nina

    2011-04-01

    DOSY is a recognized, efficient technique in the analysis of mixtures. It relies on the differences in self-diffusion coefficients, which are determined by the molecular size. Nowadays, efforts are directed towards devising matrices able to interact with the components of the mixture with differential affinity, and therefore capable to interfere with the diffusion processes and to display resolving power towards species of close, or even equal molecular weight, like isomers. Usually, commercial nonionic surfactants are mixtures of oligomeric species, since the head group, which is a short polyoxyehtylene chain, is somewhat polydisperse. The embedment of Igepal CA-520, 5 polyoxyethylene iso-octylphenyl ether, in an inverse microemulsion led to the separation of (1)H signals of the various oligomeric components. This ensued from the differential partitioning between the oil and the surface of the inverse micelles, which depends on the ethyleneoxide number (EON) of the head groups. Thus, it was possible to ascertain that the length distribution of the polyethyleneoxide chains is ingood agreement with the Poisson distribution theoretically predicted for the polymerization of ethylene oxide. The DOSY spectrum contributed to the assignment of the signals and afforded the partition degree, between the two environments, for each individual oligomeric species, providing further insight into nonionic inverse microemulsions, at present widely employed reaction media in the nanotechnological syntheses.

  4. (1)H and DOSY NMR spectroscopy analysis of Ligusticum porteri rhizome extracts.

    PubMed

    León, Alejandra; Chávez, María Isabel; Delgado, Guillermo

    2011-08-01

    The presence of dimeric phthalides and other constituents in extracts of the vegetal species Ligusticum porteri was established by NMR spectroscopy. In comparative qualitative (1)H NMR analyses of acetone extracts of rhizomes from fresh and dried L. porteri samples, we found that the dimeric phthalides tokinolide B (3), diligustilide (4) and riligustilide (5) were naturally produced by the plant and not post-harvest products. We also obtained DOSY (1)H NMR data that provided both virtual separation and structural information for the phthalides present in a dry acetone extract of L. porteri. In addition, we developed a protocol for the quantification of dimeric phthalides, which is performed by calculating the relative ratio of the peak area of selected proton signals for some compounds with respect to the known signal of the internal standard, 4-dimethylaminopyridine. The protocol allows the rapid and direct quantification of dimeric phthalides and others constituents in fresh L. porteri rhizomes. Copyright © 2011 John Wiley & Sons, Ltd.

  5. Gamma II

    NASA Astrophysics Data System (ADS)

    Barker, Thurburn; Castelaz, M.; Cline, J.; Owen, L.; Boehme, J.; Rottler, L.; Whitworth, C.; Clavier, D.

    2011-05-01

    GAMMA II is the Guide Star Automatic Measuring MAchine relocated from STScI to the Astronomical Photographic Data Archive (APDA) at the Pisgah Astronomical Research Institute (PARI). GAMMA II is a multi-channel laser-scanning microdensitometer that was used to measure POSS and SERC plates to create the Guide Star Catalog and the Digital Sky Survey. The microdensitometer is designed with submicron accuracy in x and y measurements using a HP 5507 laser interferometer, 15 micron sampling, and the capability to measure plates as large as 0.5-m across. GAMMA II is a vital instrument for the success of digitizing the direct, objective prism, and spectra photographic plate collections in APDA for research. We plan several targeted projects. One is a collaboration with Drs. P.D. Hemenway and R. L. Duncombe who plan to scan 1000 plates of 34 minor planets to identify systematic errors in the Fundamental System of celestial coordinates. Another is a collaboration with Dr. R. Hudec (Astronomical Institute, Academy of Sciences of the Czech Republic) who is working within the Gaia Variability Unit CU7 to digitize objective prism spectra on the Henize plates and Burrell-Schmidt plates located in APDA. These low dispersion spectral plates provide optical counterparts of celestial high-energy sources and cataclysmic variables enabling the simulation of Gaia BP/RP outputs. The astronomical community is invited to explore the more than 140,000 plates from 20 observatories now archived in APDA, and use GAMMA II. The process of relocating GAMMA to APDA, re-commissioning, and starting up the production scan programs will be described. Also, we will present planned research and future upgrades to GAMMA II.

  6. 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.

  7. Gamma Processes

    DTIC Science & Technology

    1986-01-01

    E[exp{-Bn Xn 1 U-Y nU-X vi ] - EeUY )Ee (v+Bu)X1 (2.4) where, in the last step, we have dropped the indices n and n-1 because of stationarity and...1967). "Some Problems of Statistical Inference Relating to Double-Gamma Distribution," Trabajos de Estadistica , 18, 67-87. Hugus, D. K. (1982

  8. DOSIS: a Monte Carlo simulation program for dose related studies in mammography.

    PubMed

    Delis, H; Spyrou, G; Panayiotakis, G; Tzanakos, G

    2005-06-01

    Dosimetric studies in mammography are addressed by means of a Monte Carlo simulation program. The core of this program (DOSIS: dosimetry simulation studies) is a simulation model developed using FORTRAN 90, enriched with a graphical user interface developed in MS Visual Basic. User defined mammographic technique parameters affecting breast dose are imported to the simulation model and the produced results are provided by means of both absolute (surface dose, exposure at detector plane) and relative quantities (percentage depth dose, isodose curves). The program functionality has been demonstrated in the evaluation of various mammographic examination techniques. Specifically, the influence of tube voltage and filtration on the surface dose and the exposure at detector plane has been studied utilizing a water phantom. Increase of tube voltage from 25 to 30 kVp for a Mo/Mo system resulted in a 42% decrease of the surface dose for a thick breast (6 cm), without changing the exposure at the detector plane. Use of 1.02 mm Al filter for a W anode system operating at 30 kVp resulted in a 19.1% decrease of the surface dose delivered to a 5 cm water equivalent breast. Overall, W/Al systems appear to have improved dosimetric performance, resulting up to a 65% decrease of surface dose compared to Mo/Mo systems, for identical exposures at the detector plane and breast thicknesses.

  9. Measurement of gamma and 2 beta + gamma

    SciTech Connect

    Albert, J.

    2005-01-03

    We report on the initial measurements of the angle {gamma} and the sum of angles 2{beta} +{gamma} of the Unitarity Triangle. When compared with indirect information on the value of {gamma} from other measurements of CKM parameters, the measurement of these angles will provide a precise test of Standard Model predictions, as statistics increase. There are several methods for directly measuring {gamma} and 2{beta} +{gamma}. We report on the status of each of these techniques, and the resulting constraints on the values of these angles.

  10. 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.

  11. Induction of sterility in Anastrepha Fraterculus (Diptera: Tephritidae) by gamma radiation

    SciTech Connect

    Allinghi, A.; Gramajo, C.; Willink, E.; Vilardi, J.

    2007-03-15

    In relation to the application of the sterile insect technique (SIT) for the South American fruit fly Anastrepha fraterculus (Wiedemann), we analyzed the effect on adult fertility of different doses of gamma irradiation and the age of pupae at the time of irradiation. In a first experiment, we applied doses of 50, 70, and 90 Gy to pupae at 24, 48, 72, and 96 h before adult emergence. In a second experiment we irradiated pupae 48 h before emergence with 20, 40, and 60 Gy and estimated male and female fertility and sperm transfer by irradiated males. The results indicated pupal age at irradiation does not significantly affect male fertility. If males irradiated with 60 Gy are crossed to non-irradiated females the fertility is about 1%. Females irradiated with 40 Gy did not lay eggs independently of the male to which they mated. No significant effects of radiation were observed with respect to the ability of males to transfer sperm. A dose of 70 Gy applied 48 h before adult emergence induces 100% sterility in both males and females. (author) [Spanish] Para la aplicacion de la tecnica del insecto esteril (TIE) en Anastrepha fraterculus (Wiedemann), en este trabajo analizamos el efecto de diferentes dosis de irradiacion gamma y la edad optima de la pupa al momento de la irradiacion. En el primer experimento se evaluaron las dosis de 50, 70, y 90 Gy en pupas de 24, 48, 72, y 96 h antes de la emergencia del adulto. En el segundo experimento se irradiaron pupas 48 h antes de la emergencia con dosis de 20, 40, 60 Gy y se estimo la fertilidad de los machos y las hembras, y la transferencia de espermas por los machos irradiados. Los resultados indicaron que la irradiacion no modifico significativamente la fertilidad de los machos. En las cruzas de machos irradiados a 60 Gy con hembras no irradiadas se observo 1% de eclosion larvaria, mientras que las hembras irradiadas a 40 Gy no pusieron huevos. La irradiacion no afecto significativamente la transferencia de espermas de los

  12. The gamma-ray telescope Gamma-1

    NASA Technical Reports Server (NTRS)

    Akimov, V. V.; Nesterov, V. E.; Kalinkin, L. F.; Balibanov, V. M.; Prilutsky, O. F.; Rodin, V. G.; Leikov, N. G.; Bielaoussov, A. S.; Dobrian, L. B.; Poluektov, V. P.

    1985-01-01

    French and Soviet specialists have designed and built the gamma-ray telescope GAMMA-1 to detect cosmic gamma rays above 50 MeV. The sensitive area of the detector is 1400 sq cm, energy resolution is 30% at 300 MeV, and angular resolution 1.2 deg at 300 MeV (and less than 20' arc when a coded aperture mask is used). Results on calibration of the qualification model and Monte-Carlo calculations are presented.

  13. The DOSIS -Experiment onboard the Columbus Laboratory of the International Space Station -First Mission Results from the Active DOSTEL Instruments

    NASA Astrophysics Data System (ADS)

    Burmeister, Soenke; Berger, Thomas; Beaujean, Rudolf; Boehme, Matthias; Haumann, Lutz; Kortmann, Onno; Labrenz, Johannes; Reitz, Guenther

    Besides the effects of the microgravity environment, and the psychological and psychosocial problems encountered in confined spaces, radiation is the main health detriment for long dura-tion human space missions. The radiation environment encountered in space differs in nature from that on earth, consisting mostly of high energetic ions from protons up to iron, resulting in radiation levels far exceeding the ones encountered on earth for occupational radiation workers. Accurate knowledge of the physical characteristics of the space radiation field in dependence on the solar activity, the orbital parameters and the different shielding configurations of the International Space Station ISS is therefore needed. For the investigation of the spatial and temporal distribution of the radiation field inside the European COLUMBUS module the DLR experiment DOSIS (Dose Distribution Inside the ISS) was launched on July 15th 2009 with STS-127 to the ISS. The experimental package was transferred from the Space Shuttle into COLUMBUS on July 18th. It consists in a first part of a combination of passive detector packages (PDP) distributed at 11 locations inside the European Columbus Laboratory. The second part are two active radiation detectors (DOSTELs) with a DDPU (DOSIS Data and Power Unit) in a nomex pouch (DOSIS MAIN BOX) mounted at a fixed location beneath the European Physiology Module (EPM) inside COLUMBUS. After the successful installation the active part has been activated on the 18th July 2009. Each of the DOSTEL units consists of two 6.93 cm PIPS silicon detectors forming a telescope with an opening angle of 120. The two DOSTELs are mounted with their telescope axis perpendicular to each other to investigate anisotropies of the radiation field inside the COLUMBUS module especially during the passes through the South Atlantic Anomaly (SAA) and during Solar Particle Events (SPEs). The data from the DOSTEL units are transferred to ground via the EPM rack which is activated

  14. 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

  15. The DOSIS -Experiment onboard the Columbus Laboratory of the International Space Station -Overview and first mission results

    NASA Astrophysics Data System (ADS)

    Reitz, Guenther; Berger, Thomas; Kürner, Christine; Burmeister, Sünke; Hajek, Michael; Bilski, Pawel; Horwacik, Tomasz; Vanhavere, Filip; Spurny, Frantisek; Jadrnickova, Iva; Pálfalvi, József K.; O'Sullivan, Denis; Yasuda, Nakahiro; Uchihori, Yukio; Kitamura, Hisashi; Kodaira, Satoshi; Yukihara, Eduardo; Benton, Eric; Zapp, Neal; Gaza, Ramona; Zhou, Dazhuang; Semones, Edward; Roed, Yvonne; Boehme, Matthias; Haumann, Lutz

    Besides the effects of the microgravity environment, and the psychological and psychosocial problems encountered in confined spaces, radiation is the main health detriment for long dura-tion human space missions. The radiation environment encountered in space differs in nature from that on earth, consisting mostly of high energetic ions from protons up to iron, resulting in radiation levels far exceeding the ones encountered on earth for occupational radiation workers. Accurate knowledge of the physical characteristics of the space radiation field in dependence on the solar activity, the orbital parameters and the different shielding configurations of the International Space Station ISS is therefore needed. The DOSIS (Dose Distribution inside the ISS) experiment, under the project and science lead of DLR, aims for the spatial and tempo-ral measurement of the radiation field parameters inside the European Columbus laboratory onboard the International Space Station. This goal is achieved by applying a combination of passive (Thermo-and Optical luminescence detectors and Nuclear track etch detectors) and active (silicon telescope) radiation detectors. The passive radiation detectors -so called pas-sive detector packages (PDP) are mounted at eleven positions within the Columbus laboratory -aiming for a spatial dose distribution measurement of the absorbed dose, the linear energy transfer spectra and the dose equivalent with an average exposure time of six months. Two active silicon telescopes -so called Dosimetry Telescopes (DOSTEL 1 and DOSTEL 2) together with a Data and Power Unit (DDPU) are mounted within the DOSIS Main Box at a fixed loca-tion beneath the European Physiology Module (EPM) rack. The DOSTEL 1 and DOSTEL 2 detectors are positioned at a 90 angle to each other for a precise measurement of the temporal and spatial variation of the radiation field, especially during crossing of the South Atlantic Anomaly (SAA). The DOSIS hardware was launched with the

  16. Preparation and characterization of CdSe colloidal quantum dots by pptical spectroscopy and 2D DOSY NMR

    NASA Astrophysics Data System (ADS)

    Geru, I.; Bordian, O.; Culeac, I.; Turta, C.; Verlan, V.; Barba, A.

    2015-02-01

    We present experimental results on preparation and characterization of colloidal CdSe quantum dots (QD) in organic solvent. CdSe QDs were synthesized following a modified literature method and have been characterized by UV-Vis absorption and photoluminescent (PL) spectroscopy, as well as by 2D Diffusion Ordered Spectroscopy (DOSY) NMR. The average CdSe particles size estimated from the UV-Vis absorption spectra was found to be in the range 2.28 - 2.92 nm, which correlates very well with the results obtained from NMR measurements. The PL spectrum for CdSe nanodots can be characterized by a narrow emission band with the peak maximum shifting from 508 to 566 nm in dependence of the CdSe nanoparticle size. The PL is dominated by a near-band-edge emission, accompanied by a weak broad band in the near IR, related to the surface shallow trap emission.

  17. Gamma Dose Distribution Studies in Ducted Shield Material Having Different Configurations

    NASA Astrophysics Data System (ADS)

    Sayed Ahmed, F. M.

    In the present work the radial distribution of total gamma doses arising from the interaction of reactor neutrons and gamma radiations inside ilmenite heavy concrete shield are measured. The ilmenite concrete is pierced with neutral beam injector ducts having different diameters and lengths. The results obtained show a relative increase in radial gamma doses at a distance of 10 cm from the neutral beam end. An empirical formula was obtained, fitting the measured gamma doses at the peak position in good agreement within a factor of 1.27. Moreover the variation of the total gamma radiation was measured along straight filled ducted with different diameters and length. The experimental data obtained show a reasonable agreement with calculated ones. The scattered as well as unscattered components of the gamma radiation transmitted through a straight duct were investigated. An empirical formula describing this behaviour was obtained.Translated AbstractDie Untersuchung der Dosisverteilung in verschieden konfigurierten Schirmmaterialien mit DurchführungenIn der vorliegenden Arbeit wird die radiale Verteilung der totalen -Dosis gemessen, wie sie aus der Wechselwirkung von Reaktorneutronen und -Strahlung innerhalb eines Betonschirms entsteht. Der Beton ist mit verschieden großen und langen Durchführungen versehen. Die erhaltenen Resultate zeigen einen relativen Intensitätspik 10 cm vor Durchführungsende. Eine empirische Formel wird aufgestellt, die diese Verhältnisse relativ gut (um den Faktor 1.27) wiedergibt. Darüber hinaus wurde die Gamma-Strahlung entlang gerader, gefüllter Durchführungen unterschiedlicher Abmessungen gemessen. Übereinstimmung mit berechneten Werten konnte erzielt werden. Sowohl die gestreuten als auch die ungestreuten Komponenten der Gamma-Strahlung in einer geraden Durchführung wurden untersucht und eine beschriebene, empirische Formel dafür angegeben.

  18. 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.

  19. Kombinierte Hoch-/Niedrig-Dosis-Therapie mit systemischen Glukokor-tikoiden bei schweren Verlaufsformen der Alopecia areata im Kindesalter.

    PubMed

    Jahn-Bassler, Karin; Bauer, Wolfgang Michael; Karlhofer, Franz; Vossen, Matthias G; Stingl, Georg

    2017-01-01

    Schwere Verlaufsformen der Alopecia areata (AA) im Kindesalter sind aufgrund limitierter Optionen therapeutisch herausfordernd. Systemische, hochdosierte Glukokortikoide weisen die schnellste Ansprechrate auf, nach dem Absetzen kommt es allerdings zu Rezidiven. Eine längerfristige Hochdosis-Anwendung ist aufgrund der zu erwartenden Nebenwirkungen nicht empfehlenswert. Eine dauerhafte Steroiderhaltungstherapie unterhalb der Cushing-Schwellen-Dosis nach Bolustherapie könnte die Krankheitsaktivität ohne Nebenwirkungen längerfristig unterdrücken. Im Rahmen einer offenen Anwendungsbeobachtung wurden 13 Kinder mit schweren Formen der AA in diese Studie eingeschlossen. Bei sieben Kindern lag eine AA totalis/universalis vor, bei sechs eine multifokale AA mit Befall von mehr als 50 % der Kopfhaut. Das Therapieregime sah eine initiale Prednisolon-Dosierung von 2 mg/kg Körpergeweicht (KG) vor und wurde innerhalb von neun Wochen auf eine Erhaltungsdosierung unter der individuellen Cushing-Schwelle reduziert. Der Nachbeobachtungszeitraum betrug ein bis drei Jahre. Wir beobachteten in 62 % aller Fälle ein komplettes Nachwachsen der Haare. Die mittlere Dauer bis zum Ansprechen lag bei 6,6 Wochen und konnte mit der Erhaltungstherapie über den gesamten Beobachtungszeitraum aufrechterhalten werden. An Nebenwirkungen wurden ausschließlich eine Gewichtszunahme (1-3 kg) bei allen Behandelten sowie eine milde Steroidakne in 23 % der Fälle beobachtet. Die kombinierte Hoch-/Niedrig-Dosis-Therapie mit systemischen Glukokortikoiden mittels Prednisolon zeigte eine hohe, dauerhafte Ansprechrate ohne signifikante Nebenwirkungen. © 2017 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.

  20. 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.

  1. Gamma-ray waveguides

    SciTech Connect

    Tournear, D. M.; Hoffbauer, M. A.; Akhadov, E. A.; Chen, A. T.; Pendleton, S. J.; Williamson, T. L.; Cha, K. C.; Epstein, R. I.

    2008-04-14

    We have developed an approach for gamma-ray optics using layered structures acting as planar waveguides. Experiments demonstrating channeling of 122 keV gamma rays in two prototype waveguides validate the feasibility of this technology. Gamma-ray waveguides allow one to control the direction of radiation up to a few MeV. The waveguides are conceptually similar to polycapillary optics, but can function at higher gamma-ray energies. Optics comprised of these waveguides will be able to collect radiation from small solid angles or concentrate radiation into small area detectors. Gamma-ray waveguides may find applications in medical imaging and treatment, astrophysics, and homeland security.

  2. Sola dosis facit venenum. Leukemia in gene therapy trials: a question of vectors, inserts and dosage?

    PubMed

    Staal, F J T; Pike-Overzet, K; Ng, Y Y; van Dongen, J J M

    2008-10-01

    In clinical gene therapy trials for X-linked severe combined immunodeficiency, the development of leukemia has come up as a severe adverse effect. In all five cases, T-cell acute lymphoblastic leukemia (T-ALL) occurred as a direct consequence of insertional mutagenesis by the retrovirus used to deliver the therapeutic gene. Here, we review the mechanisms of insertional mutagenesis, the function of the Il2RG gene and the future developments in the field. New lentiviral and gamma retroviral vectors can significantly improve the safety profile of the tools used but still carry the risk of insertional mutagenesis, as shown in this issue of Leukemia. Finally, the unfortunate side effects of gene therapy have given more insight into the development of human T-ALL.

  3. 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)

  4. Gamma titanium aluminide alloys

    SciTech Connect

    Yamaguchi, M.; Inui, H.; Kishida, K.; Matsumuro, M.; Shirai, Y.

    1995-08-01

    Extensive progress and improvements have been made in the science and technology of gamma titanium aluminide alloys within the last decade. In particular, the understanding of their microstructural characteristics and property/microstructure relationships has been substantially deepened. Based on these achievements, various engineering two-phase gamma alloys have been developed and their mechanical and chemical properties have been assessed. Aircraft and automotive industries arc pursuing their introduction for various structural components. At the same time, recent basic studies on the mechanical properties of two-phase gamma alloys, in particular with a controlled lamellar structure have provided a considerable amount of fundamental information on the deformation and fracture mechanisms of the two-phase gamma alloys. The results of such basic studies are incorporated in the recent alloy and microstructure design of two-phase gamma alloys. In this paper, such recent advances in the research and development of the two-phase gamma alloys and industrial involvement are summarized.

  5. Indirect Signatures of CP Violation in the Processes {gamma}{gamma} {yields} {gamma}{gamma}, {gamma}Z, and ZZ

    SciTech Connect

    Petriello, Frank J

    2001-07-25

    This paper studies the utility of the processes {gamma}{gamma} {yields} {gamma}{gamma}, {gamma}Z, and ZZ in searching for sources of CP violation arising from energy scales beyond the production thresholds of planned future colliders. In the context of an effective Lagrangian approach we consider the most general set of CP odd SU(2) x U(1) operators that give rise to genuinely quartic gauge boson couplings which can be probed in 2 {yields} 2 scattering processes at a {gamma}{gamma} collider. We study each process in detail, emphasizing the complementary information that is obtained by varying the initial beam polarizations. Finally, we compare our results to other constraints in the literature on CP odd gauge boson interactions and quartic gauge boson couplings; the search reaches obtained here are typically stronger and nicely complement previous studies which have focused primarily on W boson, top quark, or Higgs production.

  6. 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.

  7. {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.

  8. 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.

  9. 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.

  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 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.

  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. Optical gamma thermometer

    DOEpatents

    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.

  14. Sneaky Gamma-Rays: Using Gravitational Lensing to Avoid Gamma-Gamma-Absorption

    NASA Astrophysics Data System (ADS)

    Boettcher, Markus; Barnacka, Anna

    2014-08-01

    It has recently been suggested that gravitational lensing studies of gamma-ray blazars might be a promising avenue to probe the location of the gamma-ray emitting region in blazars. Motivated by these prospects, we have investigated potential gamma-gamma absorption signatures of intervening lenses in the very-high-energy gamma-ray emission from lensedblazars. We considered intervening galaxies and individual stars within these galaxies. We find that the collective radiation field of galaxies acting as sources of macrolensing are not expected to lead to significant gamma-gamma absorption. Individual stars within intervening galaxies could, in principle, cause a significant opacity to gamma-gamma absorption for VHE gamma-rays if the impact parameter (the distance of closest approach of the gamma-ray to the center of the star) is small enough. However, we find that the curvature of the photon path due to gravitational lensing will cause gamma-ray photons to maintain a sufficiently large distance from such stars to avoid significant gamma-gamma absorption. This re-inforces the prospect of gravitational-lensing studies of gamma-ray blazars without interference due to gamma-gamma absorption due to the lensing objects.

  15. 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.

  16. THE {gamma}SF METHOD

    SciTech Connect

    Utsunomiya, H.; Akimune, H.; Yamagata, T.; Kondo, T.; Iwamoto, C.; Okamoto, A.; Goriely, S.; Harada, H.; Kitatani, F.; Goko, S.; Toyokawa, H.; Yamada, K.; Lui, Y.-W.; Hilaire, S.; Koning, A. J.

    2011-10-28

    The {gamma}-ray strength function ({gamma}SF) interconnects radiative neutron capture and photoneutron emission as a common ingredient in the statistical model. Outlined here is an indirect method of determining radiative neutron-capture cross sections for unstable nuclei based on the {gamma}-ray strength function. Application examples of the {gamma}SF method are demonstrated.

  17. 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.

  18. 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.

  19. 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

  20. Gamma-Ray Telescopes

    NASA Astrophysics Data System (ADS)

    Weekes, T.; Murdin, P.

    2000-11-01

    Gamma-rays are the highest-energy photons in the ELECTROMAGNETIC SPECTRUM and their detection presents unique challenges. On one hand it is easy to detect γ-rays. The interaction cross-sections are large and above a few MeV the pair production interaction, the dominant γ-ray interaction with matter, is easily recognized. Gamma-ray detectors were far advanced when the concept of `γ-ray astronomy' ...

  1. [Gamma (or immune) interferon].

    PubMed

    Maniu, H

    1987-01-01

    Research on interferon progressed very much during the last years, especially studies on the gamma type of interferon. Historical data about the research conducted on the gamma interferon, its inductors, its physical, chemical and biological properties, the methods of preparation and purification, as well as the perspective of therapeutical utilisation of this type of interferon, in spite of some reversible side effects, are presented and discussed.

  2. 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.

  3. The GAMMA-400 gamma-ray telescope angular resolution

    NASA Astrophysics Data System (ADS)

    Kheymits, Maxim; Leonov, Alexey

    The measurements of gamma-ray fluxes and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV, which will be realized by the specially designed GAMMA-400 gamma-ray telescope, concern with the following broad range of science topics. Search for signatures of dark matter, surveying the celestial sphere in order to study point and extended sources of gamma-rays, measuring the energy spectra of Galactic and extragalactic diffuse gamma-ray emission, study of gamma-ray bursts and gamma-ray emission from the Sun. To clarify these scientific problems with the new experimental data the GAMMA-400 gamma-ray telescope possesses unique physical characteristics comparing with previous and present experiments. For gamma-ray energies more than 100 GeV GAMMA-400 provides the energy resolution nearby 1% and angular resolution better than 0.02 deg. The methods, developed to reconstruct the direction of incident gamma photon, are presented in this paper. The main point concerns with the space topology of high energy gamma photon interaction in the matter of GAMMA-400. Multiple secondary particles, generated inside gamma-ray telescope, produce significant problems to restore the direction of initial gamma photon. Also back-splash particles, i.e., charged particles and gamma photons generated in calorimeter and moved upward, mask the initial tracks of electron/positron pair from conversion of incident gamma photon. The processed methods allow us to reconstruct the direction of electromagnetic shower axis and extract the electron/positron trace. As a result, the direction of incident gamma photon with the energy of 100 GeV is calculated with an accuracy of more than 0.02 deg.

  4. DOSY NMR and MALDI-TOF evidence of covalent binding the DNA duplex by trimethylammonium salts of topotecan upon near UV irradiation.

    PubMed

    Naumczuk, Beata; Hyz, Karolina; Kawęcki, Robert; Bocian, Wojciech; Bednarek, Elżbieta; Sitkowski, Jerzy; Wielgus, Ewelina; Kozerski, Lech

    2015-08-01

    Using DOSY NMR and MALDI-TOF MS techniques, we present evidence that quaternary trimethylammonium salts of topotecan, [TPT-NMe3 ](+) X(-) (X = CF3SO3, HCOO), bind covalently the natural DNA oligomer upon near UV irradiation in water under physiological conditions. It is shown that formate salt is very reactive at pH 7 and requires short irradiation time. This weak irradiation at 365 nm paves the way for a new application of TPT derivatives in clinical use, which can dramatically increase the therapeutic effects of a medicine.

  5. Solvation chemistry of water-soluble thiol-protected gold nanocluster Au₁₀₂ from DOSY NMR spectroscopy and DFT calculations.

    PubMed

    Salorinne, Kirsi; Lahtinen, Tanja; Malola, Sami; Koivisto, Jaakko; Häkkinen, Hannu

    2014-07-21

    The hydrodynamic diameter of Aum(pMBA)n [(m, n) = (102, 44) and (144, 60)] clusters in aqueous media was determined via DOSY NMR spectroscopy. The apparent size of the same (n, m) cluster depends on the counter ion of the deprotonated pMBA(-) ligand as explained by the competing ion-pair strength and hydrogen bonding interactions studied in DFT calculations. The choice of the counter ion affects the surface chemistry and molecular structure at the organic/water interface, which is relevant for biological applications.

  6. The Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Kniffen, Donald A.

    1991-01-01

    The Gamma Ray Observatory (GRO), scheduled for launch by the Space Shuttle in April 1991, weighs 35,000 lbs and will offer 10 to 20 times better sensitivity than any previous gamma ray mission. The four instruments aboard GRO are described. The Burst and Transient Source Experiment (BATSE) will continuously monitor the entire sky for transient gamma-ray events using eight identical, wide-field detectors capable of measuring brightness variations lasting only milliseconds at energies from about 50,000 to 600,000 eV. The Oriented Scintillation Spectrometer Experiment (OSSE) will make comprehensive observations of discrete sources at energies from 100,000 to 10 million eV, where many radioactive elements have emission lines. The observatory's Imaging Compton Telescope will conduct a deep survey of the entire sky at gamma-ray energies between 1 and 30 MeV. The Energetic Gamma Ray Experiment Telescope will cover a broad high-energy spectral range, from about 20 million to 30 billion eV and conduct a sensitive all-sky survey with a wide field of view and good angular resolution.

  7. 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.

  8. 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.

  9. 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.

  10. Scission gamma rays

    SciTech Connect

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Kuznetsov, V. L.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2009-11-15

    Gamma rays probably emitted by the fissioning nucleus {sup 236}U* at the instant of the break of the neck or within the time of about 10{sup -21} s after or before this were discovered in the experiment devoted to searches for the effect of rotation of the fissioning nucleus in the process {sup 235}U(n,{gamma}f) and performed in a polarized beam of cold neutrons from the MEPHISTO Guideline at the FRM II Munich reactor. Detailed investigations revealed that the angular distribution of these gamma rays is compatible with the assumption of the dipole character of the radiation and that their energy spectrum differs substantially from the spectrum of prompt fission gamma rays. In the measured interval 250-600 keV, this spectrum can be described by an exponential function at the exponent value of {alpha} = -5 x 10{sup -3} keV{sup -1}. The mechanism of radiation of such gamma rays is not known at the present time. Theoretical models based on the phenomenon of the electric giant dipole resonance in a strongly deformed fissioning nucleus or in a fission fragment predict harder radiation whose spectrum differs substantially from the spectrum measured in the present study.

  11. Gamma synthetic hydrographs

    NASA Astrophysics Data System (ADS)

    Croley, Thomas E.

    1980-05-01

    The two-parameter Gamma distribution is presented as a basis for synthetic hydrographs with a review of existing applications and non-feasible applications are identified. Several approaches for fitting this function to practical boundary condition parameters are identified and presented in a unified treatment. They are especially designed for use on small programmable calculators since the synthetic hydrograph is extremely sensitive to the Gamma distribution parameters. Nomographs would give large errors in the fit for small errors in the boundary condition parameters. Although non-dimensionalization of the synthetic hydrograph is possible with the Gamma distribution, it is shown to be unnecessary. Current uses of "standard" non-dimensional hydrographs are shown to be in error.

  12. Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Meszaros, Peter

    2012-01-01

    Gamma-ray bursts (GRBs) are bright flashes of gamma-rays coming from the cosmos. They occur roughly once per day ,last typically lOs 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 afterglows.

  13. 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.

  14. Gamma-ray Polarimetry

    SciTech Connect

    Tajima, Hiroyasu

    2003-02-05

    An astrophysics application of a low noise Double-sided Silicon Strip Detector (DSSD) is described. A Semiconductor Multiple-Compton Telescope (SMCT) is being developed to explore the gamma-ray universe in the 0.1-20 MeV energy band. Excellent energy resolution and polarization sensitivity are key features of the SMCT. We have developed prototype modules for a low-noise DSSD system, which reached an energy resolution of 1.3 keV (FWHM) for 122 keV at 0 C. Results of a gamma-ray imaging test are also presented.

  15. Gamma knife surgery for craniopharyngioma.

    PubMed

    Prasad, D; Steiner, M; Steiner, L

    1995-01-01

    We present our results of Gamma Knife surgery for craniopharyngioma in nine patients. The current status of surgery, radiation therapy, intracavitary instillation of radionucleides and Gamma Knife surgery in the management of craniopharyngiomas is discussed.

  16. Interferon Gamma-1b Injection

    MedlinePlus

    Interferon gamma-1b injection is used to reduce the frequency and severity of serious infections in people ... with severe, malignant osteopetrosis (an inherited bone disease). Interferon gamma-1b is in a class of medications ...

  17. 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.

  18. Fusion gamma diagnostics

    NASA Astrophysics Data System (ADS)

    Medley, S. S.; Cecil, F. E.; Cole, D.; Conway, M. A.; Wilkinson, F. J., III

    1985-05-01

    Nuclear reactions of interest in fusion research often possess a branch yielding prompt emission of gamma radiation in excess of 15 MeV which can be exploited to provide a new fusion reaction diagnostic having applications similar to conventional neutron emission measurements. Conceptual aspects of fusion gamma diagnostics are discussed with emphasis on application to the Tokamak Fusion Test Reactor (TFTR) during deuterium neutral beam heating of D-T and D-3He plasmas. Recent measurements of the D (T, γ)5He, D(3He, γ)5Li, and D(D, γ)4He branching ratios at low center-of-mass energy (30-100 keV) and of the response of a large volume Ne226 detector for gamma detection in high neutron backgrounds are presented. Using a well-shielded Ne226 detector during 20 MW-120 kV deuterium beam heating of a tritium plasma in TFTR, the D(T, γ)5He gamma signal level is estimated to be 3.5×105 cps.

  19. 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.

  20. 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.

  1. The Universe in Gamma Rays

    NASA Astrophysics Data System (ADS)

    Schönfelder, Volker

    After describing cosmic gamma-ray production and absorption, the instrumentation used in gamma-ray astronomy is explained. The main part of the book deals with astronomical results, including the somewhat surprising result that the gamma-ray sky is continuously changing.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Gamma ray collimator

    NASA Technical Reports Server (NTRS)

    Casanova, Edgar J. (Inventor)

    1993-01-01

    A gamma ray collimator including a housing having first and second sections. 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.

  11. NIF Gamma Reaction History

    NASA Astrophysics Data System (ADS)

    Herrmann, H. W.; Kim, Y.; Young, C. S.; Mack, J. M.; McEvoy, A. M.; Hoffman, N. M.; Wilson, D. C.; Langenbrunner, J. R.; Evans, S.; Batha, S. H.; Stoeffl, W.; Lee, A.; Horsfield, C. J.; Rubery, M.; Miller, E. K.; Malone, R. M.; Kaufman, M. I.

    2010-11-01

    The primary objective of the NIF Gamma Reaction History (GRH) diagnostics is to provide bang time and burn width information based upon measurement of fusion gamma-rays. This is accomplished with energy-thresholded Gas Cherenkov detectors that convert MeV gamma-rays into UV/visible photons for high-bandwidth optical detection. In addition, the GRH detectors can perform γ-ray spectroscopy to explore other nuclear processes from which additional significant implosion parameters may be inferred (e.g., plastic ablator areal density). Implementation is occurring in 2 phases: 1) four PMT-based channels mounted to the outside of the NIF target chamber at ˜6 m from TCC (GRH-6m) for the 3e13-3e16 DT neutron yield range expected during the early ignition-tuning campaigns; and 2) several channels located just inside the target bay shield wall at ˜15 m from TCC (GRH-15m) with optical paths leading through the wall into well-shielded streak cameras and PMTs for the 1e16-1e20 yield range expected during the DT ignition campaign. This suite of diagnostics will allow exploration of interesting γ-ray physics well beyond the ignition campaign. Recent data from OMEGA and NIF will be shown.

  12. The DRAGO gamma camera

    SciTech Connect

    Fiorini, C.; Gola, A.; Peloso, R.; Longoni, A.; Lechner, P.; Soltau, H.; Strueder, L.; Ottobrini, L.; Martelli, C.; Lui, R.; Madaschi, L.; Belloli, S.

    2010-04-15

    In this work, we present the results of the experimental characterization of the DRAGO (DRift detector Array-based Gamma camera for Oncology), a detection system developed for high-spatial resolution gamma-ray imaging. This camera is based on a monolithic array of 77 silicon drift detectors (SDDs), with a total active area of 6.7 cm{sup 2}, coupled to a single 5-mm-thick CsI(Tl) scintillator crystal. The use of an array of SDDs provides a high quantum efficiency for the detection of the scintillation light together with a very low electronics noise. A very compact detection module based on the use of integrated readout circuits was developed. The performances achieved in gamma-ray imaging using this camera are reported here. When imaging a 0.2 mm collimated {sup 57}Co source (122 keV) over different points of the active area, a spatial resolution ranging from 0.25 to 0.5 mm was measured. The depth-of-interaction capability of the detector, thanks to the use of a Maximum Likelihood reconstruction algorithm, was also investigated by imaging a collimated beam tilted to an angle of 45 deg. with respect to the scintillator surface. Finally, the imager was characterized with in vivo measurements on mice, in a real preclinical environment.

  13. 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.

  14. Lunar based gamma ray astronomy

    NASA Astrophysics Data System (ADS)

    Haymes, R. C.

    Gamma ray astronomy represents the study of the universe on the basis of the electromagnetic radiation with the highest energy. Gamma ray astronomy provides a crucial tool for the understanding of astronomical phenomena, taking into account nucleosynthesis in supernovae, black holes, active galaxies, quasars, the sources of cosmic rays, neutron stars, and matter-antimatter annihilation. Difficulties concerning the conduction of studies by gamma ray astronomy are related to the necessity to perform such studies far from earth because the atmosphere is a source of gamma rays. Studies involving the use of gamma ray instruments in earth orbit have been conducted, and more gamma ray astronomy observations are planned for the future. Imperfections of studies conducted in low earth orbit could be overcome by estalishing an observatory on the moon which represents a satellite orbiting at 60 earth radii. Details concerning such an observatory are discussed.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Gamma rays for pedestrians

    SciTech Connect

    Lipkin, H.J.

    1987-05-07

    Nuclear gamma radiation does not have many of the properties taken for granted in atomic or molecular radiation and necessary for lasers. The basic science and technology underlying these differences and the proposed methods of overcoming difficulties resulting from them are not properly understood. Considerable illumination in this interdisciplinary problem could be provided by some back-of-the-envelope calculations and simple experimental surveys by small groups of students and postdocs with an elementary knowledge of the nuclear and solid state physics which is evidently not familiar these days to laser physicists. 3 refs.

  20. gamma* gamma --> pi pi at large Q{sup 2}

    SciTech Connect

    Diehl, Markus

    2000-10-18

    The QCD analysis of the process {gamma}*{gamma} {yields} {pi}{pi} at large Q{sup 2} and small center-of-mass energy allows one to access a new hadronic observable describing the exclusive transition from a q {bar q} or gg state to a pair of mesons. A fruitful study may be envisaged at existing machines.

  1. 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.

  2. 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.

  3. Colliding. gamma. e and. gamma gamma. beams from single-pass e/sup +/e/sup -/ accelerators

    SciTech Connect

    Ginzburg, I.F.; Kotkin, G.L.; Serbo, V.G.; Tel'nov, V.I.

    1983-08-01

    A detailed discussion is given of the main characteristics of ..gamma..e and ..gamma gamma.. collisions in the scheme previously proposed by the authors for obtaining colliding ..gamma..e and ..gamma gamma.. beams on the basis of the planned linear accelerators with e/sup +/e/sup -/ colliding beams VLEPP and SLC. It is proposed to obtain intense ..gamma.. beams with energy ..omega..approx.E/sub e/> or =50 GeV by scattering of laser light focused onto the electron beams of these accelerators. In the case when the maximum luminosity is achieved, L/sub gammae/approx.L/sub e/e or L/sub gammagamma/approx.L/sub e/e, the distribution of the luminosity in the invariant mass of the ..gamma..e or ..gamma gamma.. system is broad. Monochromatization of the collisions to a level 5--10% is possible. It involves a decrease of luminosity and is most efficient for use of electrons and laser photons with helicities of opposite sign. Examples of interesting physics problems for the proposed ..gamma..e and ..gamma gamma.. beams are given.

  4. 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.

  5. 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.

  6. 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.

  7. The Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Chipman, E.; Kniffen, D.

    1994-01-01

    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.

  8. 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.

  9. Gamma-ray burst observations

    NASA Technical Reports Server (NTRS)

    Atteia, J.-L.

    1993-01-01

    The most important observational characteristics of gamma-ray bursts are reviewed, with emphasis on X-ray and gamma-ray data. The observations are used to derive some basic properties of the sources. The sources are found to be isotropically distributed; the burster population is limited in space, and the edge of the distribution is visible.

  10. 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.

  11. 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.

  12. Gamma Ray Pulsars: Multiwavelength Observations

    NASA Technical Reports Server (NTRS)

    Thompson, David J.

    2004-01-01

    High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The seven or more pulsars seen by instruments on the Compton Gamma Ray Observatory (CGRO) show that: the light curves usually have double-peak structures (suggesting a broad cone of emission); gamma rays are frequently the dominant component of the radiated power; and all the spectra show evidence of a high-energy turnover. For all the known gamma-ray pulsars, multiwavelength observations and theoretical models based on such observations offer the prospect of gaining a broad understanding of these rotating neutron stars. The Gamma-ray Large Area Space Telescope (GLAST), now in planning for a launch in 2006, will provide a major advance in sensitivity, energy range, and sky coverage.

  13. Pixelated gamma detector

    SciTech Connect

    Dolinsky, Sergei Ivanovich; Yanoff, Brian David; Guida, Renato; Ivan, Adrian

    2016-12-27

    A pixelated gamma detector includes a scintillator column assembly having scintillator crystals and optical transparent elements alternating along a longitudinal axis, a collimator assembly having longitudinal walls separated by collimator septum, the collimator septum spaced apart to form collimator channels, the scintillator column assembly positioned adjacent to the collimator assembly so that the respective ones of the scintillator crystal are positioned adjacent to respective ones of the collimator channels, the respective ones of the optical transparent element are positioned adjacent to respective ones of the collimator septum, and a first photosensor and a second photosensor, the first and the second photosensor each connected to an opposing end of the scintillator column assembly. A system and a method for inspecting and/or detecting defects in an interior of an object are also disclosed.

  14. 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.

  15. Galactic plane gamma-radiation

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Fichtel, C. E.; Ogelman, H. B.; Tumer, T.; Ozel, M. E.

    1979-01-01

    Analysis of the SAS 2 data together with the COS B results shows that the distribution of galactic gamma-radiation has several similarities to that of other large-scale tracers of galactic structure. The radiation is primarily confined to a thin disc which exhibits offsets from b = 0 degrees similar to warping at radio frequencies. The principal distinction of the gamma-radiation is a stronger contrast in intensity between the region from 310 to 45 degrees in longitude and the regions away from the center that can be attributed to a variation in cosmic-ray density as a function of position in Galaxy. The diffuse galactic gamma-ray energy spectrum shows no significant variation in direction, and the spectrum seen along the plane is the same as that for the galactic component of the gamma-radiation at high altitudes. The uniformity of the galactic gamma-ray spectrum, the smooth decrease in intensity as a function of altitude, and the absence of any galactic gamma-ray sources at high altitudes indicate a diffuse origin for bulk of the galactic gamma-radiation rather than a collection of localized sources.

  16. Towards an amplitude analysis of exclusive. gamma gamma. processes

    SciTech Connect

    Pennington, M.R.

    1988-06-01

    The potential of two photon processes to shed light on the parton content of resonances, we maintain, can only be realized in practice by moving towards an Amplitude Analysis of experimental data. By using the process ..gamma gamma.. ..-->.. ..pi pi.. as an example, the way to do this is discussed. Presently claimed uncertainties in the ..gamma gamma.. width of even the well-known f/sub 2/ (1270) are shown to be over-optimistic and the fitted couplings of the overlapping scalar states in the 1 GeV region meaningless. Only the use of Amplitude Analysis techniques on the new higher statistics data from SLAC and DESY can resolve these uncertainties and lead to definite and significant results. 37 refs., 18 figs.

  17. Gamma radiation from radio pulsars

    NASA Technical Reports Server (NTRS)

    Ruderman, Malvin

    1990-01-01

    The probable magnetospheric location and source of the gamma ray emission from some young radiopulsars is discussed. The suggested evolution of this emission as a function of pulsar period gives a diminished gamma-ray luminosity for a more rapidly spinning pre-Crab pulsar. A greatly enhanced one, similar to that of unidentified Cos B sources, is predicted for a slightly slower post-Vela pulsar, followed by a relatively rapid quenching of the gamma-ray luminosity at still longer periods. Possible anomalous exo-magnetospheric pulsed MeV and TeV-PeV radiation from the Crab pulsar is considered.

  18. Cen A Optical Gamma Composite

    NASA Image and Video Library

    2017-09-28

    NASA release April 1, 2010 The gamma-ray output from Cen A's lobes exceeds their radio output by more than ten times. High-energy gamma rays detected by Fermi's Large Area Telescope are depicted as purple in this gamma ray/optical composite of the galaxy. Credit: NASA/DOE/Fermi LAT Collaboration, Capella Observatory To learn more about these images go to: www.nasa.gov/mission_pages/GLAST/news/smokestack-plumes.html NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

  19. Jet Shockwaves Produce Gamma Rays

    NASA Image and Video Library

    Theorists believe that GRB jets produce gamma rays by two processes involving shock waves. Shells of material within the jet move at different speeds and collide, generating internal shock waves th...

  20. Gamma rays at airplane altitudes

    SciTech Connect

    Iwai, J.; Koss, T.; Lord, J.; Strausz, S.; Wilkes, J.; Woosley, J. )

    1990-03-20

    An examination of the gamma ray flux above 1 TeV in the atmosphere is needed to better understand the anomalous showers from point sources. Suggestions are made for future experiments on board airplanes.

  1. Line positions and intensities for the gamma 1 + gamma 2 and gamma 2 + gamma 3 bands of (16)O3

    NASA Technical Reports Server (NTRS)

    Devi, V. Malathy; Flaud, J.-M.; Canypeyret, C.; Rinsland, C. P.; Smith, M. A. H.

    1988-01-01

    Using 0.005 cm-resolution Fourier transform spectra of (16)O3, generated by electric discharge from a greater than 99.98 percent pure sample of (16)O3, an extensive analysis of the gamma 1 + gamma 2 and the gamma 2 + gamma 3 bands in the 5.7 micron region was performed. The rotational energy levels of the upper (110) and (011) vibrational states of (16)O3 were reproduced within their experimental uncertainties using a Hamiltonian which takes explicitly into account the Coriolis-type interaction occurring between the rotational energy levels of both states. Improved vibrational energies and rotational and coupling constants were also derived for the (110) and (011) states. Precise transition moment constants for these two bands were deduced from analysis of 220 measured line intensities. Finally, a complete list of line positions, intensities, and lower state energies for both bands has been generated.

  2. The GAMMA-400 Space Experiment

    NASA Astrophysics Data System (ADS)

    Bongi, M.

    2014-06-01

    GAMMA-400 is a new space experiment which will study gamma rays and cosmic rays from about 100 MeV up to some TeVs. The proposed instrument has an angular resolution ˜ 0.1 degrees at 10 GeV and better than ˜ 0.02 degrees above 100 GeV, and an energy resolution ˜ 1% at E > 100 GeV for gamma rays. With these characteristics the experiment will be able to contribute to the search for signatures of Dark Matter, and to the study of Galactic and ex-tragalactic gamma sources and diffuse emission. A large segmented calorimeter more than 25 X0 deep will allow the study of high-energy electrons, and the measurement of the flux of protons and nuclei up to the "knee" region.

  3. Gamma-ray-selected AGN

    NASA Astrophysics Data System (ADS)

    Giommi, Paolo

    2016-08-01

    The gamma-ray band is the most energetic part of the electromagnetic spectrum. As such it is also where selection effects are most severe, as it can only be reached by the most extreme non-thermal AGN. Blazars, with their emission dominated by non-thermal blue-shifted radiation arising in a relativistic jet pointed in the direction of the observer, naturally satisfy this though requirement. For this reason, albeit these sources are intrisically very rare (orders of magnitude less abundant than radio quiet AGN of the same optical magnitude) they almost completely dominate the extragalactic gamma-ray and very high energy sky. I will discuss the emission of different types of blazars and the selection effects that are at play in the gamma-ray band based on recent results from the current generation of gamma-ray astronomy satellites, ground-based Cherenkov telescopes, and Monte Carlo simulations.

  4. Gamma Astrometric Measurement Experiment

    NASA Astrophysics Data System (ADS)

    Gai, M.; Lattanzi, M. G.; Ligori, S.; Loreggia, D.; Vecchiato, A.

    GAME aims at the measurement of gravitational deflection of the light by the Sun, by an optimised telescope on board a small class satellite. The targeted precision on the gamma parameter of the Parametrised Post-Newtonian formulation of General Relativity is below 10-6, i.e. one to two orders of magnitude better than the best current results. Such precision is suitable to detect possible deviations from the unity value, associated to generalised Einstein models for gravitation, with potentially huge impacts on the cosmological distribution of dark matter and dark energy. The measurement principle is based on differential astrometry. The observations also allow additional scientific objectives related to tests of General Relativity and to the study of exo-planetary systems. The instrument concept is based on a dual field, multiple aperture Fizeau interferometer, observing simultaneously two regions close to the Solar limb. The diluted optics achieves efficient rejection of the solar radiation, with good angular resolution on the science targets. We describe the science motivation, the proposed mission implementation and the expected performance.

  5. Spectrum Roentgen Gamma

    NASA Astrophysics Data System (ADS)

    Predehl, P.; Pavlinsky, M.

    2014-07-01

    Spectrum Roentgen Gamma (SRG) is an X-ray astrophysical observatory, developed by Russia in collaboration with Germany. The mission will be launched in 2016 into a 6-month-period halo orbit around L2. The mission lifetime is planned to be more than seven years. While the first four years of the mission are devoted to an all sky survey, the rest of the mssion will be used for pointed observations. The payload consists of two X-ray telescopes, eROSITA and ART-XC. The eROSITA sky survey will be about 30 times more sensitive than ROSAT at energies between 0.5 and 2 keV, while in the hard band (2-8 keV) it will provide the first ever true imaging survey of the sky. The design driving science is the detection of large samples of galaxy clusters out to redshifts z>1 in order to study the large scale structure in the universe and test cosmological models including Dark Energy. ART-XC's role is to extend the energy range of eROSITA alone, thereby doubling the effective area in the critical 4-7 keV range. The harder response of ART-XC also facilitates the x-ray detection of obscured AGN. Both instruments are currently in the flight model and calibration phase.

  6. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1995-10-17

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  7. Directional detector of gamma rays

    DOEpatents

    Cox, Samson A.; Levert, Francis E.

    1979-01-01

    A directional detector of gamma rays comprises a strip of an electrical cuctor of high atomic number backed with a strip of a second electrical conductor of low atomic number. These elements are enclosed within an electrical conductor that establishes an electrical ground, maintains a vacuum enclosure and screens out low-energy gamma rays. The detector exhibits a directional sensitivity marked by an increased output in the favored direction by a factor of ten over the output in the unfavored direction.

  8. Positronium Annihilation Gamma Ray Laser

    DTIC Science & Technology

    2009-07-01

    estimate of the ignition threshold for DT fuel heated by a burst from an annihilation gamma ray laser; and (IV) A new concept for more rapid laser...distribution; (III) A theoretical estimate of the ignition threshold for DT fuel heated by a burst from an annihilation gamma ray laser; and (IV) A new ...II. Development of Laser systems 26 III. Preliminary estimate of DT ignition 31 IV. New method for cooling positronium 34 CONCLUSIONS

  9. About cosmic gamma ray lines

    NASA Astrophysics Data System (ADS)

    Diehl, Roland

    2017-06-01

    Gamma ray lines from cosmic sources convey the action of nuclear reactions in cosmic sites and their impacts on astrophysical objects. Gamma rays at characteristic energies result from nuclear transitions following radioactive decays or high-energy collisions with excitation of nuclei. The gamma-ray line from the annihilation of positrons at 511 keV falls into the same energy window, although of different origin. We present here the concepts of cosmic gamma ray spectrometry and the corresponding instruments and missions, followed by a discussion of recent results and the challenges and open issues for the future. Among the lessons learned are the diffuse radioactive afterglow of massive-star nucleosynthesis in 26Al and 60Fe gamma rays, which is now being exploited towards the cycle of matter driven by massive stars and their supernovae; large interstellar cavities and superbubbles have been recognised to be of key importance here. Also, constraints on the complex processes making stars explode as either thermonuclear or core-collapse supernovae are being illuminated by gamma-ray lines, in this case from shortlived radioactivities from 56Ni and 44Ti decays. In particular, the three-dimensionality and asphericities that have recently been recognised as important are enlightened in different ways through such gamma-ray line spectroscopy. Finally, the distribution of positron annihilation gamma ray emission with its puzzling bulge-dominated intensity disctribution is measured through spatially-resolved spectra, which indicate that annihilation conditions may differ in different parts of our Galaxy. But it is now understood that a variety of sources may feed positrons into the interstellar medium, and their characteristics largely get lost during slowing down and propagation of positrons before annihilation; a recent microquasar flare was caught as an opportunity to see positrons annihilate at a source.

  10. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H.

    1994-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  11. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H.

    1995-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  12. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1994-08-16

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  13. Gamma-Rhythmic Gain Modulation.

    PubMed

    Ni, Jianguang; Wunderle, Thomas; Lewis, Christopher Murphy; Desimone, Robert; Diester, Ilka; Fries, Pascal

    2016-10-05

    Cognition requires the dynamic modulation of effective connectivity, i.e., the modulation of the postsynaptic neuronal response to a given input. If postsynaptic neurons are rhythmically active, this might entail rhythmic gain modulation, such that inputs synchronized to phases of high gain benefit from enhanced effective connectivity. We show that visually induced gamma-band activity in awake macaque area V4 rhythmically modulates responses to unpredictable stimulus events. This modulation exceeded a simple additive superposition of a constant response onto ongoing gamma-rhythmic firing, demonstrating the modulation of multiplicative gain. Gamma phases leading to strongest neuronal responses also led to shortest behavioral reaction times, suggesting functional relevance of the effect. Furthermore, we find that constant optogenetic stimulation of anesthetized cat area 21a produces gamma-band activity entailing a similar gain modulation. As the gamma rhythm in area 21a did not spread backward to area 17, this suggests that postsynaptic gamma is sufficient for gain modulation. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Spontaneous Gamma Activity in Schizophrenia.

    PubMed

    Hirano, Yoji; Oribe, Naoya; Kanba, Shigenobu; Onitsuka, Toshiaki; Nestor, Paul G; Spencer, Kevin M

    2015-08-01

    A major goal of translational neuroscience is to identify neural circuit abnormalities in neuropsychiatric disorders that can be studied in animal models to facilitate the development of new treatments. Oscillations in the gamma band (30-100 Hz) of the electroencephalogram have received considerable interest as the basic mechanisms underlying these oscillations are understood, and gamma abnormalities have been found in schizophrenia (SZ). Animal models of SZ based on hypofunction of the N-methyl-d-aspartate receptor (NMDAR) demonstrate increased spontaneous broadband gamma power, but this phenomenon has not been identified clearly in patients with SZ. To examine spontaneous gamma power and its relationship to evoked gamma oscillations in the auditory cortex of patients with SZ. We performed a cross-sectional study including 24 patients with chronic SZ and 24 matched healthy control participants at the Veterans Affairs Boston Healthcare System from January 1, 2009, through December 31, 2012. Electroencephalograms were obtained during auditory steady-state stimulation at multiple frequencies (20, 30, and 40 Hz) and during a resting state in 18 participants in each group. Electroencephalographic activity in the auditory cortex was estimated using dipole source localization. Auditory steady-state response (ASSR) measures included the phase-locking factor and evoked power. Spontaneous gamma power was measured as induced (non-phase-locked) gamma power in the ASSR data and as total gamma power in the resting-state data. The ASSR phase-locking factor was reduced significantly in patients with SZ compared with controls for the 40-Hz stimulation (mean [SD], 0.075 [0.028] vs 0.113 [0.065]; F1,46 = 6.79 [P = .012]) but not the 20- or the 30-Hz stimulation (0.042 [0.038] vs 0.043 [0.034]; F1,46 = 0.006 [P = .938] and 0.084 [0.040] vs 0.098 [0.050]; F1,46 = 1.605 [P = .212], respectively), repeating previous findings. The mean [SD] broadband-induced (30

  15. IL-4 plus CD40 monoclonal antibody induces human B cells gamma subclass-specific isotype switch: switching to gamma 1, gamma 3, and gamma 4, but not gamma 2.

    PubMed

    Fujieda, S; Zhang, K; Saxon, A

    1995-09-01

    Stimulation with IL-4 plus CD40 mAb is known to induce production of IgE and IgG4. In this study, we determined the IgG subclass specificity of IL-4 plus CD40 mAb stimulation for human purified B cells. We determined true in vitro switching by the generation of switch circular DNA (S gamma/S mu) representing primary S mu/S gamma events and production of gamma subclass-specific germ-line transcripts by a combination of reverse transcription-PCR and restriction endonuclease digestion. We simultaneously measured changes in the levels of IgG subclass proteins produced. Forty-two clones of circular switch DNA were identified and sequenced. The IgG subclass of S gamma fragment in the S gamma/S mu chimeric PCR products was determined by analyzing key S gamma nucleotides. The switch-deleted clones were found to consist of S gamma 1/S mu, S gamma 3/S mu, and S gamma 4/S mu chimeric switch sequences, showing that such switching had occurred. No S gamma 2/S mu chimeric switch sequences were found. While a consensus sequence was not identified at the S gamma/S mu breakpoints, four contiguous guanines (GGGG) were noticeably present in the S gamma region near the breakpoint. The induction of gamma 1, gamma 3, and gamma 4 switch circles in human purified B cells was accompanied by enhanced production of IgG1, IgG3, and IgG4 but not IgG2. Similarly, stimulation with IL-4 alone induced gamma 1, gamma 3, and gamma 4 but not gamma 2 germ-line transcripts. These results demonstrate that IL-4 plus CD40 mAb induces Ig isotype switch from mu to gamma 1, gamma 3, and gamma 4 but not to gamma 2.

  16. The Compton Gamma Ray Observatory

    NASA Astrophysics Data System (ADS)

    Gehrels, N.; Chipman, E.; Kniffen, D. A.

    1993-01-01

    The Arthur Holly Compton Gamma Ray Observatory (Compton) was launched by the Space Shuttle Atlantis on 5 April 1991. The spacecraft and instruments are in good health and returning exciting results. The mission provides nearly six orders of magnitude in spectral coverage, from 30 keV to 30 GeV, with sensitivity over the entire range an order of magnitude better than that of previous observations. The 16,000 kilogram observatory contains four instruments on a stabilized platform. The mission began normal operations on 16 May 1991 and is now over half-way through a full-sky survey. The mission duration is expected to be from six to ten years. A Science Support Center has been established at Goddard Space Flight Center for the purpose of supporting a vigorous Guest Investigator Program. New scientific results to date include: (1) the establishment of the isotropy, combined with spatial inhomogeneity, of the distribution of gamma-ray bursts in the sky; (2) the discovery of intense high energy (100 MeV) gamma-ray emission from 3C 279 and other quasars and BL Lac objects, making these the most distant and luminous gamma-ray sources ever detected; (3) one of the first images of a gamma-ray burst; (4) the observation of intense nuclear and position-annihilation gamma-ray lines and neutrons from several large solar flares; and (5) the detection of a third gamma-ray pulsar, plus several other transient and pulsing hard X-ray sources.

  17. Implications of final L3 measurement of {sigma}{sub tot}({gamma}{gamma}{yields}bb)

    SciTech Connect

    Chyla, Jiri

    2006-02-01

    The excess of data on the total cross section of bb production in {gamma}{gamma} collisions over QCD predictions, observed by L3, OPAL and DELPHI Collaborations at LEP2, has so far defied explanation. The recent final analysis of L3 data has brought important new information concerning the dependence of the observed excess on the {gamma}{gamma} collisions energy W{sub {gamma}}{sub {gamma}}. The implications of this dependence are discussed.

  18. Flavonoid glycosides from Persea caerulea. Unraveling their interactions with SDS-micelles through matrix-assisted DOSY, PGSE, mass spectrometry, and NOESY.

    PubMed

    Álvarez, Juan M; Raya-Barón, Álvaro; Nieto, Pedro M; Cuca, Luis E; Carrasco-Pancorbo, Alegría; Fernández-Gutiérrez, Alberto; Fernández, Ignacio

    2016-04-13

    Two flavonoid glycosides derived from rhamnopyranoside (1) and arabinofuranoside (2) have been isolated from leaves of Persea caerulea for the first time. The structures of 1 and 2 have been established by (1) H NMR, (13) C NMR, and IR spectroscopy, together with LC-ESI-TOF and LC-ESI-IT MS spectrometry. From the MS and MS/MS data, the molecular weights of the intact molecules as well as those of quercetin and kaempferol together with their sugar moieties were deduced. The NMR data provided information on the identity of the compounds, as well as the α and β configurations and the position of the glycosides on quercetin and kaempferol. We have also explored the application of sodium dodecyl sulfate (SDS) normal micelles in binary aqueous solution, at a range of concentrations, to the diffusion resolution of these two glycosides, by the application of matrix-assisted diffusion ordered spectroscopy (DOSY) and pulse field gradient spin echo (PGSE) methodologies, showing that SDS micelles offer a significant resolution which can, in part, be rationalized in terms of differing degrees of hydrophobicity, amphiphilicity, and steric effects. In addition, intra-residue and inter-residue proton-proton distances using nuclear Overhauser effect build-up curves were used to elucidate the conformational preferences of these two flavonoid glycosides when interacting with the micelles. By the combination of both diffusion and nuclear Overhauser spectroscopy techniques, the average location site of kaempferol and quercetin glycosides has been postulated, with the former exhibiting a clear insertion into the interior of the SDS-micelle, whereas the latter is placed closer to the surface. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  19. The Gamma-ray Sky with Fermi

    NASA Technical Reports Server (NTRS)

    Thompson, David

    2012-01-01

    Gamma rays reveal extreme, nonthermal conditions in the Universe. The Fermi Gamma-ray Space Telescope has been exploring the gamma-ray sky for more than four years, enabling a search for powerful transients like gamma-ray bursts, novae, solar flares, and flaring active galactic nuclei, as well as long-term studies including pulsars, binary systems, supernova remnants, and searches for predicted sources of gamma rays such as dark matter annihilation. Some results include a stringent limit on Lorentz invariance derived from a gamma-ray burst, unexpected gamma-ray variability from the Crab Nebula, a huge gamma-ray structure associated with the center of our galaxy, surprising behavior from some gamma-ray binary systems, and a possible constraint on some WIMP models for dark matter.

  20. LHC prospects in searches for neutral scalars in pp {sup {yields}} {gamma}{gamma} + jet

    SciTech Connect

    Demidov, S. V. Gorbunov, D. S.

    2006-04-15

    At hadron colliders, the {gamma}{gamma} + jet channel provides a larger signal-to-background ratio in comparison with the inclusive {gamma}{gamma} channel in hunting for scalars uncharged under the SM gauge group. By using NLO results for the SM Higgs boson production and corresponding background, we estimate LHC prospects in searches for the radion and sgoldstino in the {gamma}{gamma} + jet channel. Three-body final-state kinematics allows for refined cuts. We have found that this channel could be comparable with the {gamma}{gamma} channel in searches for new physics.

  1. Quasars, blazars, and gamma rays.

    PubMed

    Dermer, C D; Schlickeiser, R

    1992-09-18

    Before the launch of the Compton Gamma Ray Observatory (CGRO), the only source of >100-megaelectron volt (MeV) gamma radiation known outside our galaxy was the quasar 3C 273. After less than a year of observing, 13 other extragalactic sources have been discovered with the Energetic Gamma Ray Experiment Telescope (EGRET) on CGRO, and it is expected that many more will be found before the full sky survey is complete. All 14 sources show evidence of blazar properties at other wavelengths; these properties include high optical polarization, extreme optical variability, flat-spectrum radio emission associated with a compact core, and apparent superluminal motion. Such properties are thought to be produced by those few, rare extragalactic radio galaxies and quasars that are favorably aligned to permit us to look almost directly down a relativistically outflowing jet of matter expelled from a supermassive black hole. Although the origin of the gamma rays from radio jets is a subject of much controversy, the gamma-ray window probed by CGRO is providing a wealth of knowledge about the central engines of active galactic nuclei and the most energetic processes occurring in nature.

  2. Quality assurance for gamma knives

    SciTech Connect

    Jones, E.D.; Banks, W.W.; Fischer, L.E.

    1995-09-01

    This report describes and summarizes the results of a quality assurance (QA) study of the Gamma Knife, a nuclear medical device used for the gamma irradiation of intracranial lesions. Focus was on the physical aspects of QA and did not address issues that are essentially medical, such as patient selection or prescription of dose. A risk-based QA assessment approach was used. Sample programs for quality control and assurance are included. The use of the Gamma Knife was found to conform to existing standards and guidelines concerning radiation safety and quality control of external beam therapies (shielding, safety reviews, radiation surveys, interlock systems, exposure monitoring, good medical physics practices, etc.) and to be compliant with NRC teletherapy regulations. There are, however, current practices for the Gamma Knife not covered by existing, formalized regulations, standards, or guidelines. These practices have been adopted by Gamma Knife users and continue to be developed with further experience. Some of these have appeared in publications or presentations and are slowly finding their way into recommendations of professional organizations.

  3. The neutron-gamma Feynman variance to mean approach: Gamma detection and total neutron-gamma detection (theory and practice)

    NASA Astrophysics Data System (ADS)

    Chernikova, Dina; Axell, Kåre; Avdic, Senada; Pázsit, Imre; Nordlund, Anders; Allard, Stefan

    2015-05-01

    Two versions of the neutron-gamma variance to mean (Feynman-alpha method or Feynman-Y function) formula for either gamma detection only or total neutron-gamma detection, respectively, are derived and compared in this paper. The new formulas have particular importance for detectors of either gamma photons or detectors sensitive to both neutron and gamma radiation. If applied to a plastic or liquid scintillation detector, the total neutron-gamma detection Feynman-Y expression corresponds to a situation where no discrimination is made between neutrons and gamma particles. The gamma variance to mean formulas are useful when a detector of only gamma radiation is used or when working with a combined neutron-gamma detector at high count rates. The theoretical derivation is based on the Chapman-Kolmogorov equation with the inclusion of general reactions and corresponding intensities for neutrons and gammas, but with the inclusion of prompt reactions only. A one energy group approximation is considered. The comparison of the two different theories is made by using reaction intensities obtained in MCNPX simulations with a simplified geometry for two scintillation detectors and a 252Cf-source. In addition, the variance to mean ratios, neutron, gamma and total neutron-gamma are evaluated experimentally for a weak 252Cf neutron-gamma source, a 137Cs random gamma source and a 22Na correlated gamma source. Due to the focus being on the possibility of using neutron-gamma variance to mean theories for both reactor and safeguards applications, we limited the present study to the general analytical expressions for Feynman-alpha formulas.

  4. The Gamma-Ray Observatory

    SciTech Connect

    Kniffen, D.A. )

    1989-01-01

    The scientific goals and the design of the NASA Gamma-Ray Observatory (GRO), planned for launch in mid-1990, are described together with the experiments to be performed on the GRO mission and the instruments to be flown on the Observatory. GRO contains a complement of four instruments to span the spectrum from 0.03 to 20,000 MeV in energy, three of which are optimized to make gamma-ray observations using either the photoelectric effect, the Compton scatter, or the pair production processes; the fourth instrument is optimized for high-sensitivity observations of transient events and time-variable sources. The instruments are the Oriented Scintillation Spectrometer Experiment, the Compton Telescope, the Energetic Gamma-Ray Experiment Telescope, and the Burst and Transient Source Experiment.

  5. Magnetars as soft gamma repeaters

    NASA Astrophysics Data System (ADS)

    O'Meara, Karen

    1999-05-01

    The source of non-periodic, repeating, gamma-ray bursts located within our galaxy and near supernova remnants has been a mystery. A new theory by Christopher Thompson and Robert Duncan, postulating the existence of young neutron stars with intense magnetic fields (1E14 Gauss or more) offers an explanation. The intense magnetic fields of these "magnetars" suffice to create the phenomena detected from soft gamma-ray repeaters. The poles of a magnetar are hot enough to emit steady, low level x-ray emissions. Stresses on the star's crust due to the drifting of the magnetic field through the superfluid core create seismic activity and "starquakes," which release enormous bursts of energy. Data collected from recent soft gamma-ray repeater bursts appear to be strong evidence in support of this exciting new theory.

  6. Design and Performance of the GAMMA-400 Gamma-Ray Telescope for Dark Matter Searches

    NASA Technical Reports Server (NTRS)

    Galper, A.M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A.I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu. V.; Kaplin, V. A.; Kachanov, V. A.; Kheymits, M. D.; Leonov, A. A.; Longo, F.; Mazets, E. P.; Maestro, P.; Marrocchesi, P.; Mereminskiy, I. A.; Mikhailov, V. V.; Moiseev, A. A.; Mocchiutti, E.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu.; Papini, P.; Picozza, P.; Rodin, V. G.; Runtso, M. F.; Sparvoli, R.; Spillantini, P.; Suchkov, S. I.; Tavani, M.; Topchiev, N. P.; Vacchi, A.

    2012-01-01

    The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma-rays and cosmic-ray electrons + positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma-rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is approx. 0.01 deg (E(sub gamma) > 100 GeV), the energy resolution approx. 1% (E(sub gamma) > 10 GeV), and the proton rejection factor approx 10(exp 6). GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

  7. Design and Performance of the GAMMA-400 Gamma-Ray Telescope for Dark Matter Searches

    NASA Technical Reports Server (NTRS)

    Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu V.; Kaplin, V. A.; Kachanov, V. A.; Kheymits, M. D.; Leonov, A. A.; Longo, F.; Mazets, E. P.; Maestro, P.; Marrocchesi, P.; Mereminskiy, I. A.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu

    2012-01-01

    The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma-rays and cosmic-ray electrons (+) positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma-rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is approximately 0.01deg (E(sub gamma) greater than 100 GeV), the energy resolution approximately 1% (E(sub gamma) greater than 10 GeV), and the proton rejection factor approximately 10(exp 6). GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

  8. Towed seabed gamma ray spectrometer

    SciTech Connect

    Jones, D.G. )

    1994-08-01

    For more than 50 years, the measurement of radioactivity has been used for onshore geological surveys and in laboratories. The British Geological Survey (BGS) has extended the use of this type of equipment to the marine environment with the development of seabed gamma ray spectrometer systems. The present seabed gamma ray spectrometer, known as the Eel, has been successfully used for sediment and solid rock mapping, mineral exploration, and radioactive pollution studies. The range of applications for the system continues to expand. This paper examines the technological aspects of the Eel and some of the applications for which it has been used.

  9. Gamma-ray Imaging Methods

    SciTech Connect

    Vetter, K; Mihailescu, L; Nelson, K; Valentine, J; Wright, D

    2006-10-05

    In this document we discuss specific implementations for gamma-ray imaging instruments including the principle of operation and describe systems which have been built and demonstrated as well as systems currently under development. There are several fundamentally different technologies each with specific operational requirements and performance trade offs. We provide an overview of the different gamma-ray imaging techniques and briefly discuss challenges and limitations associated with each modality (in the appendix we give detailed descriptions of specific implementations for many of these technologies). In Section 3 we summarize the performance and operational aspects in tabular form as an aid for comparing technologies and mapping technologies to potential applications.

  10. Gamma source for active interrogation

    DOEpatents

    Leung, Ka-Ngo; Lou, Tak Pui; Barletta, William A.

    2009-09-29

    A cylindrical gamma generator includes a coaxial RF-driven plasma ion source and target. A hydrogen plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical gamma generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which has many openings. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired.

  11. Gamma source for active interrogation

    SciTech Connect

    Leung, Ka-Ngo; Lou, Tak Pui; Barletta, William A.

    2012-10-02

    A cylindrical gamma generator includes a coaxial RF-driven plasma ion source and target. A hydrogen plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical gamma generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which has many openings. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired.

  12. BETA-GAMMA PERSONNEL DOSIMETER

    DOEpatents

    Davis, D.M.; Gupton, E.D.; Hart, J.C.; Hull, A.P.

    1961-01-17

    A personnel dosimeter is offered which is sensitive to both gamma and soft beta radiations from all directions within a hemisphere. The device is in the shape of a small pill box which is worn on a worker-s wrist. The top and sides of the device are provided with 50 per cent void areas to give 50 per cent response to the beta rays and complete response to the gamma rays. The device is so constructed as to have a response which will approximate the dose received by the basal layer of the human epidermis.

  13. sin 2 beta + gamma Measurements

    SciTech Connect

    Therin, G; /Paris U., VI-VII

    2005-06-24

    I report on the most recent measurements done to constrain sin(2{beta}+{gamma}) with neutral B mesons. Direct measurements of 2{beta} + {gamma} will provide a precise test of the standard model predictions with higher statistics. Present constraints come from studies of B {yields} D{sup (*){+-}}{pi}{sup {-+}}/{rho}{sup {-+}} decays done by BABAR and Belle collaborations with full and inclusive techniques to reconstruct B mesons. B {yields} D{sup 0(*)}K{sup 0} decays are also very promising but statistics are too low to give any constraint at the moment.

  14. gamma-Carboxyglutamic acid distribution.

    PubMed

    Zytkovicz, T H; Nelsestuen, G L

    1976-09-24

    The distribution of the vitamin K-dependent amino acid, gamma-carboxyglutamic acid was examined in proteins from a variety of sources. Proteins examined include purified rat and bovine coagulation proteins, barium citrate-adsorbing proteins from trout plasma, lamprey plasma, earthworm hemolymph, army worm hemolymph, lobster hemolymph, E. coli B/5, soybean leaf, the protein lysate from the hemolymph cell of the horseshoe crab and parathyroid extract. Other purified proteins examined included human alpha-1-antitrypsin, pepsinogen, S-100, fetuin, tropomyosin-troponin and complement protein C-3. Of these, only the blood-cotting proteins and the vertebrate plasma samples were shown to contain gamma-carboxyglutamic acid.

  15. Nuclear fuel microsphere gamma analyzer

    DOEpatents

    Valentine, Kenneth H.; Long, Jr., Ernest L.; Willey, Melvin G.

    1977-01-01

    A gamma analyzer system is provided for the analysis of nuclear fuel microspheres and other radioactive particles. The system consists of an analysis turntable with means for loading, in sequence, a plurality of stations within the turntable; a gamma ray detector for determining the spectrum of a sample in one section; means for analyzing the spectrum; and a receiver turntable to collect the analyzed material in stations according to the spectrum analysis. Accordingly, particles may be sorted according to their quality; e.g., fuel particles with fractured coatings may be separated from those that are not fractured, or according to other properties.

  16. Gamma radiation characteristics of plutonium dioxide fuel

    NASA Technical Reports Server (NTRS)

    Gingo, P. J.

    1969-01-01

    Investigation of plutonium dioxide as an isotopic fuel for Radioisotope Thermoelectric Generators yielded the isotopic composition of production-grade plutonium dioxide fuel, sources of gamma radiation produced by plutonium isotopes, and the gamma flux at the surface.

  17. On Some Properties of Gamma Matrices

    ERIC Educational Resources Information Center

    Dumais, Jean-Francois

    1977-01-01

    Discusses the problem of the order, reducibility, and equivalence of systems of Dirac gamma matrices. Gives a simple systematic method for finding the matrices connecting different systems of 4 x 4 gamma matrices. (MLH)

  18. On Some Properties of Gamma Matrices

    ERIC Educational Resources Information Center

    Dumais, Jean-Francois

    1977-01-01

    Discusses the problem of the order, reducibility, and equivalence of systems of Dirac gamma matrices. Gives a simple systematic method for finding the matrices connecting different systems of 4 x 4 gamma matrices. (MLH)

  19. Swift's 500th Gamma Ray Burst

    NASA Image and Video Library

    On April 13, 2010, NASA's Swift Gamma-ray Burst Explorer satellite discovered its 500th burst. Swift's main job is to quickly localize each gamma-ray burst (GRB), report its position so that others...

  20. The Gamma-ray Universe through Fermi

    NASA Technical Reports Server (NTRS)

    Thompson, David J.

    2012-01-01

    Gamma rays, the most powerful form of light, reveal extreme conditions in the Universe. The Fermi Gamma-ray Space Telescope and its smaller cousin AGILE have been exploring the gamma-ray sky for several years, enabling a search for powerful transients like gamma-ray bursts, novae, solar flares, and flaring active galactic nuclei, as well as long-term studies including pulsars, binary systems, supernova remnants, and searches for predicted sources of gamma rays such as dark matter annihilation. Some results include a stringent limit on Lorentz invariance derived from a gamma-ray burst, unexpected gamma-ray variability from the Crab Nebula, a huge ga.nuna-ray structure associated with the center of our galaxy, surprising behavior from some gamma-ray binary systems, and a possible constraint on some WIMP models for dark matter.

  1. Portable compton gamma-ray detection system

    DOEpatents

    Rowland, Mark S.; Oldaker, Mark E.

    2008-03-04

    A Compton scattered gamma-ray detector system. The system comprises a gamma-ray spectrometer and an annular array of individual scintillators. The scintillators are positioned so that they are arrayed around the gamma-ray spectrometer. The annular array of individual scintillators includes a first scintillator. A radiation shield is positioned around the first scintillator. A multi-channel analyzer is operatively connected to the gamma-ray spectrometer and the annular array of individual scintillators.

  2. Gamma-ray camera flyby

    SciTech Connect

    2010-01-01

    Animation based on an actual classroom demonstration of the prototype CCI-2 gamma-ray camera's ability to image a hidden radioactive source, a cesium-137 line source, in three dimensions. For more information see http://newscenter.lbl.gov/feature-stories/2010/06/02/applied-nuclear-physics/.

  3. Gamma-ray Line Astronomy

    NASA Astrophysics Data System (ADS)

    Diehl, R.

    2005-07-01

    Gamma-ray lines from radioactive isotopes, ejected into interstellar space by cosmic nucleosynthesis events, are observed with new space telescopes. The Compton Observatory had provided a sky survey for the isotopes 56Co, 22Na, 44Ti, and 26Al, detecting supernova radioactivity and the diffuse glow of long-lived radioactivity from massive stars in the Galaxy. High-resolution spectroscopy is now being exploited with Ge detectors: Since 2002, with ESA's INTEGRAL satellite and the RHESSI solar imager two space-based Ge-gamma-ray telescopes are in operation, measuring Doppler broadenings and line shape details of cosmic gamma-ray lines. First year's results include a detection and line shape measurement of annihilation emission, and 26Al emission from the inner Galaxy and from the Cygnus region. 60Fe gamma-ray intensity is surprisingly low; it may have been detected by RHESSI at 10% of the 26Al brightness, yet is not seen by INTEGRAL. 44Ti emission from Cas A and SN1987A is being studied; no other candidate young supernova remnants have been found through 44Ti. 22Na from novae still is not seen.

  4. Gamma-Ray Interactions for Reachback Analysts

    SciTech Connect

    Karpius, Peter Joseph; Myers, Steven Charles

    2016-08-02

    This presentation is a part of the DHS LSS spectroscopy training course and presents an overview of the following concepts: identification and measurement of gamma rays; use of gamma counts and energies in research. Understanding the basic physics of how gamma rays interact with matter can clarify how certain features in a spectrum were produced.

  5. Gamma ray spectroscopy in astrophysics. [conferences

    NASA Technical Reports Server (NTRS)

    Cline, T. L. (Editor); Ramaty, R. (Editor)

    1978-01-01

    Experimental and theoretical aspects of gamma ray spectroscopy in high energy astrophysics are discussed. Line spectra from solar, stellar, planetary, and cosmic gamma rays are examined as well as HEAO investigations, the prospects of a gamma ray observatory, and follow-on X-ray experiments in space.

  6. Gamma and Related Functions Generalized for Sequences

    ERIC Educational Resources Information Center

    Ollerton, R. L.

    2008-01-01

    Given a sequence g[subscript k] greater than 0, the "g-factorial" product [big product][superscript k] [subscript i=1] g[subscript i] is extended from integer k to real x by generalizing properties of the gamma function [Gamma](x). The Euler-Mascheroni constant [gamma] and the beta and zeta functions are also generalized. Specific examples include…

  7. Gamma and Related Functions Generalized for Sequences

    ERIC Educational Resources Information Center

    Ollerton, R. L.

    2008-01-01

    Given a sequence g[subscript k] greater than 0, the "g-factorial" product [big product][superscript k] [subscript i=1] g[subscript i] is extended from integer k to real x by generalizing properties of the gamma function [Gamma](x). The Euler-Mascheroni constant [gamma] and the beta and zeta functions are also generalized. Specific examples include…

  8. On some problems of gamma-astronomy

    NASA Technical Reports Server (NTRS)

    Berezinsky, V. S.; Ginzburg, V. L.; Ptuskin, V. S.

    1985-01-01

    Gamma ray emissions from young supernova remnants are discussed and calculated. The positron annihilation line is also calculated. Decay of charged pions in remnants cause generation of high energy neutrinos. This emission of neutrinos is reviewed. The CR origin and gamma emission from Magellanic clouds help to establish the intensity gradient in the galaxy. This gamma astronomical data is briefly discussed.

  9. Nuclear gamma rays from energetic particle interactions

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Kozlovsky, B.; Lingenfelter, R. E.

    1978-01-01

    Gamma ray line emission from nuclear deexcitation following energetic particle reactions is evaluated. The compiled nuclear data and the calculated gamma ray spectra and intensities can be used for the study of astrophysical sites which contain large fluxes of energetic protons and nuclei. A detailed evaluation of gamma ray line production in the interstellar medium is made.

  10. Attrition resistant gamma-alumina catalyst support

    DOEpatents

    Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

    2006-03-14

    A .gamma.-alumina catalyst support having improved attrition resistance produced by a method comprising the steps of treating a particulate .gamma.-alumina material with an acidic aqueous solution comprising water and nitric acid and then, prior to adding any catalytic material thereto, calcining the treated .gamma.-alumina.

  11. Neutron/gamma coupled library generation and gamma transport calculation with KARMA 1.2

    SciTech Connect

    Hong, S. G.; Kim, K. S.; Cho, J. Y.; Lee, K. H.

    2012-07-01

    KAERI has developed a lattice transport calculation code KARMA and its multi-group cross section library generation system. Recently, the multi-group cross section library generation system has included a gamma cross section generation capability and KARMA also has been improved to include a gamma transport calculation module. This paper addresses the multi-group gamma cross section generation capability for the KARMA 1.2 code and the preliminary test results of the KARMA 1.2 gamma transport calculations. The gamma transport calculation with KARMA 1.2 gives the gamma flux, gamma smeared power, and gamma energy deposition distributions. The results of the KARMA gamma calculations were compared with those of HELIOS and they showed that KARMA 1.2 gives reasonable gamma transport calculation results. (authors)

  12. Terrestrial Gamma-Ray Flashes (TGFs)

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2010-01-01

    This slide presentation reviews the observation of Terrestrial Gamma Ray Flashes (TGFs) by Gamma-Ray Telescopes. These were: (1) BATSE /Compton Observatory, (2) Solar Spectroscopic Imager, (3) AGILE Gamma-ray Telescope, and (4) Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Space Telescope. It contains charts which display the counts over time, a map or the TGFs observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). and a map showing the latitude and longitude of 85 of the TGFs observed by the Fermi GBM.

  13. Future prospects for gamma-ray

    NASA Technical Reports Server (NTRS)

    Fichtel, C.

    1980-01-01

    Astrophysical phenomena discussed are: the very energetic and nuclear processes associated with compact objects; astrophysical nucleo-synthesis; solar particle acceleration; the chemical composition of the planets and other bodies of the solar system; the structure of our galaxy; the origin and dynamic pressure effects of the cosmic rays; the high energy particles and energetic processes in other galaxies, especially active ones; and the degree of matter antimater symmetry of the universe. The gamma ray results of GAMMA-I, the gamma ray observatory, the gamma ray burst network, solar polar, and very high energy gamma ray telescopes on the ground provide justification for more sophisticated telescopes.

  14. Compton Gamma Ray Observatory Guest Investigator Program

    NASA Technical Reports Server (NTRS)

    Lingenfelter, Richard E.

    1997-01-01

    This paper presents a final report for the Compton Gamma Ray Observatory Guest Investigator Program from 06/01/91-07/31/97. The topics include: 1) Solar Flare Neutron Spectra and Accelerated Ions; 2) Gamma Ray Lines From The Orion Complex; 3) Implications of Nuclear Line Emission From The Orion Complex; 4) Possible Sites of Nuclear Line Emission From Massive OB Associations; 5) Gamma-Ray Burst Repitition and BATSE Position Uncertainties; 6) Effects of Compton Scattering on BATSE Gamma-Ray Burst Spectra; and 7) Selection Biases on the Spectral and Temporal Distribution of Gamma Ray Bursts.

  15. INTEGRAL entdeckt den Gamma-Himmel: Gamma-Astronomie

    NASA Astrophysics Data System (ADS)

    Schönfelder, Volker

    2004-11-01

    Das Gamma-Weltraumteleskop INTEGRAL der Europäischen Weltraumbehörde, ESA, hat in den ersten 15 Monaten seiner Mission eine Fülle interessanter, neuer Ergebnisse geliefert. Hauptinstrumente an Bord sind das hoch auflösende Spektrometer SPI und das Spektrometer IBIS. Hinzu kommt je ein Monitor für den Röntgen- und optischen Bereich. Die wichtigsten neuen Erkenntnisse stammen vor allem aus dem Bereich harter kompakter Röntgenquellen und aus dem Bereich der Gammalinien-Spektroskopie. Mit INTEGRAL wurde es erstmals möglich, den diffusen galaktischen Hintergrund zum Teil mit Einzelquellen identifizieren zu können. Ferner ließ sich in der Umgebung des galaktischen Zentrums die 511-keV-Linie von annihilierenden Positronen und Elektronen nachweisen. Schließlich trägt INTEGRAL auch entscheidend zum Studium der geheimnisvollen Gamma Ray Bursts bei.

  16. BFKL resummation effects in gamma* gamma* to rho rho

    SciTech Connect

    Enberg, R.; Pire, B.; Szymanowski, L.; Wallon, S.

    2005-08-11

    We calculate the leading order BFKL amplitude for the exclusive diffractive process {gamma}*{sub L}(Q{sub 1}{sup 2}) {gamma}*{sub L}(Q{sub 2}{sup 2}) {yields} {rho}{sub L}{sup 0}{rho}{sub L}{sup 0} in the forward direction, which can be studied in future high energy e{sup +}e{sup -} linear colliders. The resummation effects are very large compared to the fixed-order calculation. We also estimate the next-to-leading logarithmic corrections to the amplitude by using a specific resummation of higher order effects and find a substantial growth with energy, but smaller than in the leading logarithmic approximation.

  17. On the origin of gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Vahia, M. N.; Rao, A. R.

    1988-03-01

    It is argued that observations of gamma ray bursts show that the neutron star model is not tenable. A similarity between gamma ray burst characteristics and solar hard X-ray flares is established. The temporal and spectral features observed in the gamma ray bursts are also seen in the solar hard X-ray flares. The only distinction is in the energy contents of the two. Gamma ray bursts may originate from sources which have Sun-like activity. Large scale Sun-like activity is observed in flare stars, RS CVn binaries, and cataclysmic variables, grouped together as magnetically active stellar systems. These systems have enough energy to produce gamma ray bursts. Positional identification between the gamma ray burst error boxes and the magnetically active stellar systems produces an association of 46 objects with 36 error boxes with a probability of chance coincidence of 10 to the minus 10th power. A gamma ray burst that has a spatial and temporal correlation to a soft X-ray flare associated with a magnetically active stellar system and another time coincidence where the gamma ray burst location is not known to be found. Gamma ray bursts should be considered the stellar equivalent of the solar hard X-ray burst. gamma ray burst location is not known are found. Gamma ray bursts should be considered as stellar equivalents of solar hard X-ray bursts.

  18. Gamma-ray astronomy: Nuclear transition region

    NASA Technical Reports Server (NTRS)

    Chupp, E. L.

    1976-01-01

    This monograph reviews the major theoretical and experimental efforts made during the past 12 years in gamma-ray astronomy over the energy range from 10 keV to about 100 MeV, where nuclear-transition lines are expected. Early attempts to detect celestial gamma rays are recounted, mechanisms of gamma-ray line and continuum production are examined, and formulas giving the various possible differential gamma-ray spectral shapes are provided. Predicted fluxes are discussed for solar gamma rays as well as for gamma emission from supernova remnants, supernovae, neutron stars, flare stars, the galactic core and disk, black holes, and diffuse sources. Gamma-ray interactions with matter are analyzed, particularly the photoelectric effect, Compton scattering from free electrons, and pair production in nuclear fields. Significant results are summarized for observations of gamma rays from the sun as well as from point and extended sources within and beyond the Galaxy, including diffuse fluxes and transient gamma-ray bursts. Factors pertaining to the design of gamma-ray astronomy experiments are considered, especially detector background limitations, gamma-ray production within instruments, and present-day detection methods.

  19. Gamma-ray astronomy: Nuclear transition region

    NASA Technical Reports Server (NTRS)

    Chupp, E. L.

    1976-01-01

    This monograph reviews the major theoretical and experimental efforts made during the past 12 years in gamma-ray astronomy over the energy range from 10 keV to about 100 MeV, where nuclear-transition lines are expected. Early attempts to detect celestial gamma rays are recounted, mechanisms of gamma-ray line and continuum production are examined, and formulas giving the various possible differential gamma-ray spectral shapes are provided. Predicted fluxes are discussed for solar gamma rays as well as for gamma emission from supernova remnants, supernovae, neutron stars, flare stars, the galactic core and disk, black holes, and diffuse sources. Gamma-ray interactions with matter are analyzed, particularly the photoelectric effect, Compton scattering from free electrons, and pair production in nuclear fields. Significant results are summarized for observations of gamma rays from the sun as well as from point and extended sources within and beyond the Galaxy, including diffuse fluxes and transient gamma-ray bursts. Factors pertaining to the design of gamma-ray astronomy experiments are considered, especially detector background limitations, gamma-ray production within instruments, and present-day detection methods.

  20. Status of the GAMMA-400 Project

    NASA Technical Reports Server (NTRS)

    Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Gusakov, Yu. V.; Farber, M. O.; hide

    2013-01-01

    The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100 MeV-3 TeV is presented. The angular resolution of the instrument, 1-2 deg at E(gamma) approximately 100 MeV and approximately 0.01 at E(gamma) greater than 100 GeV, its energy resolution is approximately 1% at E(gamma) greater than 100 GeV, and the proton rejection factor is approximately 10(exp 6) are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.

  1. Radioimmunoassay for. gamma. -melanocyte stimulating hormone

    SciTech Connect

    Shibasaki, T.; Ling, N.; Guillemin, R.

    1980-05-26

    A specific radioimmunoassay for ..gamma..-melanocyte stimulating hormone-like peptides was developed. An antiserum raised in rabbit to synthetic bovine ..gamma../sub 3/-MSH, one of the possible ..gamma..-MSH peptides, specifically recognizes the portion between His/sup 5/ and Arg/sup 14/ of ..gamma../sub 3/-MSH without significant cross-reaction with other synthetic ..gamma..-MSH-like peptides, ..cap alpha..-, ..beta..-MSH, adrenocorticotropin, and ..beta..-endorphin. The usable range of this RIA is 10 pg to 600 pg of synthetic ..gamma../sub 3/-MSH. Three immunoreactive ..gamma..-MSH peaks were thus found in gel permeation chromatography of the whole bovine pituitary extract.

  2. 2010: Status of the GAMMA-400 Project

    NASA Astrophysics Data System (ADS)

    Topchiev, Nikolay; Galper, . M.; Arkhangelskaya, I. V.; Bonvicini, V.; Boezio, M.; Dolgoshein, B. A.; Farber, M. O.; Fradkin, M. I.; Gecha, V. Ya.; Kachanov, V. A.; Kaplin, V. A.; Men'shenin, A. L.; Picozza, P.; Prilutskii, O. F.; Runtso, M. F.; Spillantini, P.; Suchkov, S. I.; Topchiev, N. P.; Vacchi, A.; Yurkin, Yu. T.; Zampa, N.; Zverev, V. G.

    An optimized version of the GAMMA-400 telescope for detecting gamma rays, electrons, and positrons in the energy range 0.1-3000 GeV and high-energy nuclei is presented. Its performance (angular resolution 0.05° , energy resolution 3%, e/p rejection factor 106 ) enables to search gamma rays, electrons, and positrons from annihilation or decay of dark matter components, to detect high-energy gamma rays from galactic and extragalactic astrophysical objects, to measure energy spectra of galactic and extragalactic diffuse gamma-ray emission, to search and investigate transient phenomena, high-energy (more than 1 GeV) gamma-ray bursts and gamma rays from solar flares, as well as galactic electron, positron, and nuclei fluxes.

  3. Gamma Radiation Doses In Sweden

    SciTech Connect

    Almgren, Sara; Isaksson, Mats; Barregaard, Lars

    2008-08-07

    Gamma dose rate measurements were performed in one urban and one rural area using thermoluminescence dosimeters (TLD) worn by 46 participants and placed in their dwellings. The personal effective dose rates were 0.096{+-}0.019(1 SD) and 0.092{+-}0.016(1 SD){mu}Sv/h in the urban and rural area, respectively. The corresponding dose rates in the dwellings were 0.11{+-}0.042(1 SD) and 0.091{+-}0.026(1 SD){mu}Sv/h. However, the differences between the areas were not significant. The values were higher in buildings made of concrete than of wood and higher in apartments than in detached houses. Also, {sup 222}Rn measurements were performed in each dwelling, which showed no correlation with the gamma dose rates in the dwellings.

  4. Cosmic gamma-ray lines

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1986-01-01

    Recent observations of gamma-ray line emissions from gamma-ray bursts, the ISM, the Galactic center, and solar flares are reviewed, and the implications of these observations for high-energy processes in these sources are discussed. Line observations suggest that magnetized neutron stars are probably the best candidate objects for burst sources. Observations of the 1.809-MeV line from Al-26 decay provide evidence for ongoing nucleosynthesis in the Galaxy and information on the spatial distribution of nucleosynthetic sites. The compact 0.511-MeV line source is probably a black hole at or close to the Galactic center. Solar-flare studies have provided new information on the confinement and escape of charged particles at the sun and on multiple acceleration phases in solar flares.

  5. Prompt-Gamma Activation Analysis.

    PubMed

    Lindstrom, Richard M

    1993-01-01

    A permanent, full-time instrument for prompt-gamma activation analysis is nearing completion as part of the Cold Neutron Research Facility (CNRF). The design of the analytical system has been optimized for high gamma detection efficiency and low background, particularly for hydrogen. Because of the purity of the neutron beam, shielding requirements are modest and the scatter-capture background is low. As a result of a compact sample-detector geometry, the sensitivity (counting rate per gram of analyte) is a factor of four better than the existing Maryland-NIST thermal-neutron instrument at this reactor. Hydrogen backgrounds of a few micrograms have already been achieved, which promises to be of value in numerous applications where quantitative nondestructive analysis of small quantities of hydrogen in materials is necessary.

  6. Gamma radiolysis of chlorinated hydrocarbons

    SciTech Connect

    Arbon, R.E.; Mincher, B.J.; Meikrantz, D.H.

    1992-08-01

    This program is the Idaho National Engineering Laboratory (INEL) component of a joint collarborative effort with Lawrence Livermore National Laboratory (LLNL). The purpose of this effort is to demonstrate a viable process for breaking down hazardous halogenated organic wastes to simpler, non-hazardous waste using high energy ionizing radiation. The INEL effort focuses on the use of spent reactor fuel gamma radiation sources to decompose complex wastes such as PCBs. At LLNL, halogenated solvents such as carbon tetrachloride and trichloroethylene are being studied using accelerator radiation sources. The INEL irradiation experiments concentrated on a single PCB congener so that a limited set of decomposition reactions could be studied. The congener 2,2{prime}, 3,3{prime},4,5{prime},6,6{prime} - octachlorobiphenyl was examined following exposure to various gamma doses at the Advanced Test Reactor (AIR) spent fuel pool. The decomposition rates and products in several solvents are discussed. 3 refs.

  7. Gamma radiolysis of chlorinated hydrocarbons

    SciTech Connect

    Arbon, R.E.; Mincher, B.J.; Meikrantz, D.H.

    1992-01-01

    This program is the Idaho National Engineering Laboratory (INEL) component of a joint collarborative effort with Lawrence Livermore National Laboratory (LLNL). The purpose of this effort is to demonstrate a viable process for breaking down hazardous halogenated organic wastes to simpler, non-hazardous waste using high energy ionizing radiation. The INEL effort focuses on the use of spent reactor fuel gamma radiation sources to decompose complex wastes such as PCBs. At LLNL, halogenated solvents such as carbon tetrachloride and trichloroethylene are being studied using accelerator radiation sources. The INEL irradiation experiments concentrated on a single PCB congener so that a limited set of decomposition reactions could be studied. The congener 2,2{prime}, 3,3{prime},4,5{prime},6,6{prime} - octachlorobiphenyl was examined following exposure to various gamma doses at the Advanced Test Reactor (AIR) spent fuel pool. The decomposition rates and products in several solvents are discussed. 3 refs.

  8. Observations of Soft Gamma Repeaters

    NASA Technical Reports Server (NTRS)

    Kouveliotou, Chryssa

    2004-01-01

    Magnetars (Soft Gamma Repeaters and Anomalous X-ray Pulsars) are a subclass of neutron stars characterized by their recurrent X-ray bursts. While in an active (bursting) state (lasting anywhere between days and years), they are emit&ng hundreds of predominantly soft (kT=30 kev), short (0.1-100 ms long) events. Their quiescent source x-ray light ewes exhibit puhlions rotational period rate changes (spin-down) indicate that their magnetic fields are extremely high, of the order of 10^14- 10^l5 G. Such high B-field objects, dubbed "magnetars", had been predicted to exist in 1992, but the first concrete observational evidence were obtained in 1998 for two of these sources. I will discuss here the history of Soft Gamma Repeaters, and their spectral, timing and flux characteristics both in the persistent and their burst emission.

  9. Temperature dependence of gamma-gamma prime lattice mismatch in nickel-base superalloys

    NASA Technical Reports Server (NTRS)

    Nathal, M. V.; Mackay, R. A.; Garlick, R. G.

    1985-01-01

    High temperature X-ray diffraction techniques were used to determine the gamma-gamma prime lattice mismatch of three different nickel-base superalloys at temperatures between 18 and 1000 C. The measurements were performed on oriented single-crystal disks which had been aged to produce a semicoherent gamma-gamma prime structure. The thermal expansion of the lattice parameters of the gamma and gamma-prime phases was described by a second-order polynomial expression. The expansion of the gamma-prime phase was consistently smaller than that of the gamma phase, which caused the lattice mismatch to become more negative at higher temperatures. It was also shown that high values of lattice mismatch resulted in increased rates of directional gamma-prime coarsening during elevated temperature creep exposure.

  10. Gamma-400 Science Objectives Built on the Current HE Gamma-Ray and CR Results

    NASA Technical Reports Server (NTRS)

    Moiseev, Alexander; Mitchell, John; Thompson, David

    2012-01-01

    The main scientific interest of the Russian Gamma-400 team: Observe gamma-rays above approximately 50 GeV with excellent energy and angular resolution with the goals of: (1) Studying the fine spectral structure of the isotropic high-energy gamma-radiation, (2) Attempting to identify the many still-unidentified Fermi-LAT gamma-ray sources. Gamma-400 will likely be the only space-based gamma-ray observatory operating at the end of the decade. In our proposed Gamma-400-LE version, it will substantially improve upon the capabilities of Fermi LAT and AGILE in both LE and HE energy range. Measuring gamma-rays from approx 20 MeV to approx 1 TeV for at least 7 years, Gamma-400-LE will address the topics of dark matter, cosmic ray origin and propagation, neutron stars, flaring pulsars, black holes, AGNs, GRBs, and actively participate in multiwavelength campaigns.

  11. Structurally divergent human T cell receptor. gamma. proteins encoded by distinct C. gamma. genes

    SciTech Connect

    Krangel, M.S.; Band, H.; Hata, S.; McLean, J.; Brenner, M.B.

    1987-07-03

    The human T cell receptor (TCR) ..gamma.. polypeptide occurs in structurally distinct forms on certain peripheral blood T lymphocytes. Complementary DNA clones representing the transcripts of functionally rearranged TCR ..gamma.. genes in these cells have been analyzed. The expression of a disulfide-linked and a nondisulfide-linked form of TCR ..gamma.. correlates with the use of the C..gamma..1 and C..gamma..2 constant-region gene segments, respectively. Variability in TCR ..gamma.. polypeptide and disulfide linkage is determined by the number of copies and the sequence of a repeated segment of the constant region. Thus, C..gamma..1 and C..gamma..2 are used to generate structurally distinct, yet functional, T3-associated receptor complexes on peripheral blood lymphocytes. Tryptic peptide mapping suggests that the T3-associated TCR ..gamma.. and delta peptides in the nondisulfide-linked form are distinct.

  12. Design and performance of the GAMMA-400 gamma-ray telescope for dark matter searches

    NASA Astrophysics Data System (ADS)

    Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu. V.; Kaplin, V. A.; Kachanov, V. A.; Kheymits, M. D.; Leonov, A. A.; Longo, F.; Mazets, E. P.; Maestro, P.; Marrocchesi, P.; Mereminskiy, I. A.; Mikhailov, V. V.; Moiseev, A. A.; Mocchiutti, E.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu.; Papini, P.; Picozza, P.; Rodin, V. G.; Runtso, M. F.; Sparvoli, R.; Spillantini, P.; Suchkov, S. I.; Tavani, M.; Topchiev, N. P.; Vacchi, A.; Vannuccini, E.; Yurkin, Yu. T.; Zampa, N.; Zverev, V. G.; Zirakashvili, V. N.

    2013-02-01

    The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma-rays and cosmic-ray electrons + positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma-rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is ~0.01° (Eγ > 100 GeV), the energy resolution ~1% (Eγ > 10 GeV), and the proton rejection factor ~106. GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

  13. Joining of Gamma Titanium Aluminides

    DTIC Science & Technology

    2002-09-01

    stimulated significant work on gas tungsten-arc welding ( GTAW ) both for the welding of individual castings into built-up structures and for the repair...environmental effect, some GTAW systems provide for the direct transfer of the welded component from the welding chamber to a vacuum furnace without cooling...the specimen to room temperature or exposing it to the atmosphere. Typical preheat and interpass temperatures for the multipass GTAW of gamma plate

  14. The Gamma Database Machine Project

    DTIC Science & Technology

    1990-03-01

    number of performance studies of the system during this period [DEWI86, DEWI88, GIIA.N89, (3HAN90]. In the spring of 1989, Gamma was ported to a 32...managed separately in order to avoid flushing hot pages from the buffer pool. While there are advantages to having these spaces managed separately by...Livny, M., S. Khoshafian, and H. Boral, "Multi-Disk Management Algorithms", Proceedings of the 1987 SIGMETRICS Conference, Banff , Alberta, Canada, May

  15. Neutron Detector Gamma Insensitivity Criteria

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Stephens, Daniel L.

    2009-10-21

    The shortage of 3He has triggered the search for an effective alternative neutron detection technology for radiation portal monitor applications. Any new detection technology must satisfy two basic criteria: 1) it must meet the neutron detection efficiency requirement, and 2) it must be insensitive to gamma ray interference at a prescribed level, while still meeting the neutron detection requirement. It is the purpose of this document to define this latter criterion.

  16. Gamma ray bursts inner engines

    NASA Astrophysics Data System (ADS)

    Staff, Jan Erling

    Long gamma ray bursts (GRBs) are brief durations of intense, highly variable gamma radiation coming from point like sources in the Universe. GRBs have been seen in connection with Type 1c supernovae. Their isotropical equivalent energy released in gamma rays is in some cases above 10 54 erg, but the engine creating this energy is unknown. In this thesis several models for the engine are explored. It is shown that cannonballs can in principle form from hyperaccreting disks, however the cannonball model requires almost all supernovae to create cannonballs, and our finding then implies that a hyperaccreting disk is a natural consequence in most supernovae, a notion which remains to be confirmed. General relativistic magnetohydrodynamic simulations of the collapsar model have been performed. Within our setup we found that the duration of the collapsar is too short to explain GRBs, and the energy output is not sufficient. Also the supernova connection could not be explained. I find that the more likely candidate for the GRB engine is an accreting quark star. A quark star has a maximum mass, if the mass increases above this the star will collapse to a black hole. This allows for a two stage engine that might be able to explain features observed in GRBs.

  17. In-Beam Gamma Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mayank, .; Muralithar, S.; Sihotra, S.; Kumar, S.; Mehta, D.; Singh, R. P.; Rathore, Urvashi

    2016-09-01

    In-beam Gamma ray spectroscopic techniques have been studied using Indian National Gamma Array, IUAC which has a relative photo-peak efficiency of 5%. Data of a previous experiment where high angular momentum states of various nuclides were populated in the fusion-evaporation reaction 75As (28Si, 2p2n) at Elab = 120MeV. When gammas from populated nuclides are emanated during de-excitation, they are emitted with a certain angular distribution depending upon their multipolarity. Angular distribution of dipole and quadrupole transitions in 96Ru has been obtained from this data. The efficiency corrected angular distribution plot has been compared with the theoretical angular distribution function. The distribution co-efficients A2 and A4 for dipole and quadrupole were extracted from fitting the distribution with the equation: W (θ) = 1 +A2 *P2(cosθ) +A4 *P4(cosθ) . The Directional-correlation of Oriented Nuclei method was used to assign various other transitions as quadrupole or dipole. A DCO matrix between detectors at 1480 versus 900 was created using CANDLE. Intensities of transitions that have similar multipolarity as the gated transition would be equal in both the projected spectrums. In case of different multipolarity intensities would vary by a factor of 2. RDCO plots for 96Ru transitions have been obtained. To determine the nature of transitions whether magnetic or electric, a plot between polarization asymmetry (Δ) and DCO-ratio for transitions in 96Ru has been obtained.

  18. {eta} Prime {yields}{pi}{sup 0}{gamma}{gamma} and {eta} Prime {yields}{eta}{gamma}{gamma}: A primer analysis

    SciTech Connect

    Escribano, Rafel

    2012-10-23

    The electromagnetic rare decays {eta} Prime {yields}{pi}{sup 0}{gamma}{gamma} and {eta} Prime {yields}{pi}{sup 0}{gamma}{gamma} are analysed for the first time and their predicted branching ratios given. The vector meson exchange dominant contribution is treated using Vector Meson Dominance and the scalar component is estimated by means of the Linear Sigma Model. The agreement between our calculation and the measurement of the related process {eta} Prime {yields}{pi}{sup 0}{gamma}{gamma} is a check of the procedure. Scalar meson effects are seen to be irrelevant for {eta} Prime {yields}{pi}{sup 0}{gamma}{gamma}, while a significant scalar contribution due to the {sigma}(500) resonance seems to emerge in the case of {eta} Prime {yields}{pi}{sup 0}{gamma}{gamma}. Future measurements coming from KLOE-2, Crystal Ball, WASA, and BES-III will elucidate if any of these processes carry an important scalar contribution or they are simply driven by the exchange of vector mesons.

  19. Growth kinetics of gamma-prime precipitates in a directionally solidified eutectic, gamma/gamma-prime-delta

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.

    1976-01-01

    A directionally solidified eutectic alloy (DSEA), of those viewed as potential candidates for the next generation of aircraft gas turbine blade materials, is studied for the gamma-prime growth kinetics, in the system Ni-Nb-Cr-Al, specifically: Ni-20 w/o Nb-6 w/o Cr-2.5 w/o Al gamma/gamma-prime-delta DSEA. Heat treatment, polishing and etching, and preparation for electron micrography are described, and the size distribution of gamma-prime phase following various anneals is plotted, along with gamma-prime growth kinetics in this specific DSEA, and the cube of gamma-prime particle size vs anneal time. Activation energies and coarsening kinetics are studied.

  20. Growth kinetics of gamma-prime precipitates in a directionally solidified eutectic, gamma/gamma-prime-delta

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.

    1976-01-01

    A directionally solidified eutectic alloy (DSEA), of those viewed as potential candidates for the next generation of aircraft gas turbine blade materials, is studied for the gamma-prime growth kinetics, in the system Ni-Nb-Cr-Al, specifically: Ni-20 w/o Nb-6 w/o Cr-2.5 w/o Al gamma/gamma-prime-delta DSEA. Heat treatment, polishing and etching, and preparation for electron micrography are described, and the size distribution of gamma-prime phase following various anneals is plotted, along with gamma-prime growth kinetics in this specific DSEA, and the cube of gamma-prime particle size vs anneal time. Activation energies and coarsening kinetics are studied.

  1. Pulsed pyroelectric crystal-powered gamma source

    SciTech Connect

    Chen, A. X.; Antolak, A. J.; Leung, K.-N.; Raber, T. N.; Morse, D. H.

    2013-04-19

    A compact pulsed gamma generator is being developed to replace radiological sources used in commercial, industrial and medical applications. Mono-energetic gammas are produced in the 0.4 - 1.0 MeV energy range using nuclear reactions such as {sup 9}Be(d,n{gamma}){sup 10}B. The gamma generator employs an RF-driven inductively coupled plasma ion source to produce deuterium ion current densities up to 2 mA/mm{sup 2} and ampere-level current pulses can be attained by utilizing an array extraction grid. The extracted deuterium ions are accelerated to approximately 300 keV via a compact stacked pyroelectric crystal system and then bombard the beryllium target to generate gammas. The resulting microsecond pulse of gammas is equivalent to a radiological source with curie-level activity.

  2. The Fermi Gamma-Ray Space Telescope

    NASA Technical Reports Server (NTRS)

    Thompson, Dave; McEnery, Julie

    2011-01-01

    This slide presentation reviews the Gamma Ray Astronomy as enhanced by the Fermi Gamma Ray Space Telescope and Radio Astronomy as a synergistic relationship. Gamma rays often represent a significant part of the energy budget of a source; therefore, gamma-ray studies can be critical to understanding physical processes in such sources. Radio observations offer timing and spatial resolutions vastly superior to anything possible with gamma-ray telescopes; therefore radio is often the key to understanding source structure. Gamma-ray and radio observations can complement each other, making a great team. It reviews the Fermi Guest Investigator (GI) program, and calls for more cooperative work that involves Fermi and the Very Long Baseline Array (VLBA), a system of ten radio telescopes.

  3. Instrumentation for gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Bertsch, David L.; Fichtel, Carl E.; Trombka, Jacob I.

    1988-01-01

    The current status of gamma-ray-telescope technology for ground, airborne, and space observations is surveyed and illustrated with drawings, diagrams, and graphs and tables of typical data. For the low- and medium-energy ranges, consideration is given to detectors and detector cooling systems, background-rejection methods, radiation damage, large-area detectors, gamma-ray imaging, data analysis, and the Compton-interaction region. Also discussed are the gamma-ray interaction process at high energies; multilevel automated spark-chamber gamma-ray telescopes; the Soviet Gamma-1 telescope; the EGRET instrument for the NASA Gamma-Ray Observatory; and Cerenkov, air-shower, and particle-detector instruments for the TeV and PeV ranges. Significant improvements in resolution and sensitivity are predicted for the near future.

  4. GAMCIT: A gamma ray burst detector

    NASA Technical Reports Server (NTRS)

    Surka, Derek M.; Grunsfeld, John M.; Warneke, Brett A.

    1992-01-01

    The origin of celestial gamma ray bursts remains one of the great mysteries of modern astrophysics. The GAMCIT Get-Away-Special payload is designed to provide new and unique data in the search for the sources of gamma ray bursts. GAMCIT consists of three gamma ray detectors, an optical CCD camera, and an intelligent electronics system. This paper describes the major components of the system, including the electronics and structural designs.

  5. Gamma-Ray Astronomy Technology Needs

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Cannizzo, J. K.

    2012-01-01

    In recent decades gamma-ray observations have become a valuable tool for studying the universe. Progress made in diverse 8re1lS such as gamma-ray bursts (GRBs), nucleosynthesis, and active galactic nuclei (AGNs) has complimented and enriched our astrophysical understanding in many ways. We present an overview of current and future planned space y-ray missions and discussion technology needs for- the next generation of space gamma-ray instruments.

  6. Gamma rays produce superior seedless citrus

    SciTech Connect

    Pyrah, D.

    1984-10-01

    Using gamma radiation, seedless forms of some varieties of oranges and grapefruit are being produced. Since it has long been known that radiation causes mutations in plants and animals, experiments were conducted to determine if seediness could be altered by exposing seeds or budwood to higher than natural doses of gamma radiation. Orange and grapefruit seeds and cuttings exposed to gamma rays in the early 1970's have produced trees that bear fruit superior to that now on the market.

  7. Understanding Doppler Broadening of Gamma Rays

    SciTech Connect

    Rawool-Sullivan, Mohini; Sullivan, John P.

    2014-07-03

    Doppler-broadened gamma ray peaks are observed routinely in the collection and analysis of gamma-ray spectra. If not recognized and understood, the appearance of Doppler broadening can complicate the interpretation of a spectrum and the correct identification of the gamma ray-emitting material. We have conducted a study using a simulation code to demonstrate how Doppler broadening arises and provide a real-world example in which Doppler broadening is found. This report describes that study and its results.

  8. Using gamma gamma coincidence measurements to validate Monte Carlo generated detector response functions

    NASA Astrophysics Data System (ADS)

    Metwally, W. A.; Gardner, R. P.; Sood, A.

    2007-10-01

    Monte Carlo simulation of gamma-ray transport for the purpose of performing elemental analysis of bulk samples requires the tracking of gamma rays in the sample and also in the detector(s) used. Detector response functions (DRF's) are an efficient and accurate variance reduction technique that greatly decreases the simulation time by substituting the tracking of gamma rays inside the detector by predefined single energy gamma-ray spectra. These spectra correspond to the average response of the detector for incident gamma rays. DRF's are generated by Monte Carlo methods and are benchmarked with experimental data. In this work, prompt gamma-gamma coincidence measurements are presented as a way to validate DRF's for high-energy gamma rays.

  9. A search for the rare decay. mu. /sup +/. -->. e/sup +/. gamma gamma

    SciTech Connect

    Grosnick, D.P.

    1987-02-01

    An experimental search for the lepton-family number nonconserving decay, ..mu../sup +/ ..-->.. e/sup +/..gamma gamma.., has been conducted at the Clinton P. Anderson Meson Physics Facility (LAMPF) using the Crystal Box detector. The detector consists of a modular NaI(Tl) calorimeter, scintillator hodoscope, and a high-resolution, cylindrical drift chamber. It provides a large solid-angle for detecting three-body decays and has good resolutions in the time, position, and energy measurements to eliminate unwanted backgrounds. No evidence for ..mu../sup +/ ..-->.. e/sup +/..gamma gamma.. is found, giving an upper limit for the branching ratio of GAMMA(..mu.. ..-->.. e..gamma gamma..)/GAMMA(..mu.. ..-->.. e nu anti nu) less than or equal to 7.2 x 10/sup -11/ (90% C.L.). This result is an improvement of more than two orders of magnitude in the existing limit. 109 refs., 39 figs.

  10. Synthesis of different chiral amino gamma-butyrolactones and amino gamma-butenolides.

    PubMed

    Concellón, José M; Riego, Estela; Bernad, Pablo L

    2002-04-18

    Different transformations of chiral epoxy esters 1 afford two different amino gamma-butyrolactones 2 and 6, and amino gamma-butenolides 8, by different nucleophilic opening-closing processes. [reaction: see text

  11. Hard gamma ray emission from blazars

    NASA Technical Reports Server (NTRS)

    Marscher, Alan P.; Bloom, Steven D.

    1992-01-01

    The gamma-ray emission expected from compact extragalactic sources of nonthermal radiation is examined. The highly variable objects in this class should produce copious amounts of self-Compton gamma-rays in the compact relativistic jet. This is shown to be a likely interpretation of the hard gamma-ray emission recently detected from the quasar 3C 279 during a period of strong nonthermal flaring at lower frequencies. Ways of discriminating between the self-Compton model and other possible gamma-ray emission mechanisms are discussed.

  12. Gamma-ray irradiated polymer optical waveguides

    SciTech Connect

    Lai, C.-C.; Wei, T.-Y.; Chang, C.-Y.; Wang, W.-S.; Wei, Y.-Y.

    2008-01-14

    Optical waveguides fabricated by gamma-ray irradiation on polymer through a gold mask are presented. The gamma-ray induced index change is found almost linearly dependent on the dose of the irradiation. And the measured propagation losses are low enough for practical application. Due to the high penetrability of gamma ray, uniform refractive index change in depth can be easily achieved. Moreover, due to large-area printing, the uniformity of waveguide made by gamma-ray irradiation is much better than that by e-beam direct writing.

  13. Low-level gamma-ray spectrometry

    SciTech Connect

    Brodzinski, R.L.

    1990-10-01

    Low-level gamma-ray spectrometry generally equates to high-sensitivity gamma-ray spectrometry that can be attained by background reduction, selective signal identification, or some combination of both. Various methods for selectively identifying gamma-ray events and for reducing the background in gamma-ray spectrometers are given. The relative magnitude of each effect on overall sensitivity and the relative cost'' for implementing them are given so that a cost/benefit comparison can be made and a sufficiently sensitive spectrometer system can be designed for any application without going to excessive or unnecessary expense. 10 refs., 8 figs.

  14. gamma-Glutamyl dipeptides in Petiveria alliacea.

    PubMed

    Kubec, Roman; Musah, Rabi A

    2005-10-01

    Three gamma-glutamyl dipeptides have been isolated from Petiveria alliacea L. roots. These dipeptides include (S(C2)R(C7))-gamma-glutamyl-S-benzylcysteine together with two diastereomeric sulfoxides, namely (S(C2)R(C7)R(S))- and (S(C2)R(C7)R(S))-gamma-glutamyl-S-benzylcysteine S-oxides (gamma-glutamyl-petiveriins A and B, respectively). Their structures and absolute configurations have been determined by NMR, MALDI-HRMS, IR and CD spectroscopy, and confirmed by comparison with authentic compounds obtained by synthesis.

  15. The Mystery of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2004-01-01

    Gamma-ray bursts remain one of the greatest mysteries in astrophysics. Observations of gamma-ray bursts made by the BATSE experiment on the Compton Gamma-Ray Observatory will be described. Most workers in the field now believe that they originate from cosmological distances. This view has been reinforced by observations this year of several optical afterglow counterparts to gamma-ray bursts. A summary of these recent discoveries will be presented, along with their implications for models of the burst emission mechanism and the energy source of the bursts.

  16. Gamma ray astronomy and black hole astrophysics

    NASA Technical Reports Server (NTRS)

    Liang, Edison P.

    1990-01-01

    The study of soft gamma emissions from black-hole candidates is identified as an important element in understanding black-hole phenomena ranging from stellar-mass black holes to AGNs. The spectra of Cyg X-1 and observations of the Galactic Center are emphasized, since thermal origins and MeV gamma-ray bumps are evident and suggest a thermal-pair cloud picture. MeV gamma-ray observations are suggested for studying black hole astrophysics such as the theorized escaping pair wind, the anticorrelation between the MeV gamma bump and the soft continuum, and the relationship between source compactness and temperature.

  17. The polarization asymmetry in {gamma}e collisions at the NLC and triple gauge Boson couplings

    SciTech Connect

    Rizzo, T.G.

    1996-09-01

    The capability of the NLC in the {gamma}e collider mode to probe the CP-conserving {gamma}WW and {gamma}ZZ anomalous couplings through the use of the polarization asymmetry is examined. When combined with other measurements, very strong constraints on both varieties of anomalous couplings can be obtained. The author shows that these bounds are complementary to those that can be extracted from data taken at the LHC.

  18. Human Fc gamma RII, in the absence of other Fc gamma receptors, mediates a phagocytic signal.

    PubMed Central

    Indik, Z; Kelly, C; Chien, P; Levinson, A I; Schreiber, A D

    1991-01-01

    Fc gamma receptors are important components in the binding and phagocytosis of IgG-sensitized cells. Studies on the role of these receptors have been limited by the fact that most hematopoietic cells express more than one Fc gamma receptor. We studied the role of Fc gamma RIIA in isolation on a human erythroleukemia cell line (HEL) which expresses Fc gamma RIIA as its only Fc gamma receptor. HEL cells were observed to bind and phagocytose IgG-sensitized red blood cells (RBCs) in a dose-dependent manner. We then examined the role of Fc gamma RI and Fc gamma RII in isolation and in combination, in transfected COS-1 cells. Fc gamma RIIA-transfected COS cells also mediated both the binding and phagocytosis of IgG-sensitized RBCs. In contrast, phagocytosis was not observed in Fc gamma RI-transfected cells, although these cells avidly bound IgG-sensitized RBCs. Furthermore, coexpression of both receptors by doubly transfected cells did not affect the phagocytic efficiency of Fc gamma RIIA. These studies establish that Fc gamma RIIA can mediate phagocytosis and suggest that transfected COS-1 cells provide a model for examining this process. Since HEL cells exhibit characteristics of cells of the megakaryocyte-platelet lineage, including expression of Fc gamma RII as the only Fc gamma receptor, Fc gamma RIIA on megakaryocytes and platelets may be involved in the ingestion of IgG-containing immune complexes. Furthermore, these studies indicate that Fc gamma RI and Fc gamma RIIA differ in their requirements for transduction of a phagocytic signal. Images PMID:1834702

  19. Diffusion welding of a directionally solidified gamma/gamma prime - delta eutectic alloy

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1977-01-01

    Hot-press diffusion welding parameters were developed for a directionally solidified, gamma/gamma prime-delta eutectic alloy. Based on metallography, a good diffusion weld was achieved at 1100 C under 34.5 MPa (5 ksi) pressure for 1 hour. In addition, a dissimilar metal weld between gamma/gamma prime-delta and IN-100 was successfully made at 1100 C under 20.7 MPa (3 ksi) pressure for 1 hour.

  20. Different origins of gamma rhythm and high-gamma activity in macaque visual cortex.

    PubMed

    Ray, Supratim; Maunsell, John H R

    2011-04-01

    During cognitive tasks electrical activity in the brain shows changes in power in specific frequency ranges, such as the alpha (8-12 Hz) or gamma (30-80 Hz) bands, as well as in a broad range above ∼80 Hz, called the high-gamma band. The role or significance of this broadband high-gamma activity is unclear. One hypothesis states that high-gamma oscillations serve just like gamma oscillations, operating at a higher frequency and consequently at a faster timescale. Another hypothesis states that high-gamma power is related to spiking activity. Because gamma power and spiking activity tend to co-vary during most stimulus manipulations (such as contrast modulations) or cognitive tasks (such as attentional modulation), it is difficult to dissociate these two hypotheses. We studied the relationship between high-gamma power, gamma rhythm, and spiking activity in the primary visual cortex (V1) of awake monkeys while varying the stimulus size, which increased the gamma power but decreased the firing rate, permitting a dissociation. We found that gamma power became anti-correlated with the high-gamma power, suggesting that the two phenomena are distinct and have different origins. On the other hand, high-gamma power remained tightly correlated with spiking activity under a wide range of stimulus manipulations. We studied this relationship using a signal processing technique called Matching Pursuit and found that action potentials are associated with sharp transients in the LFP with broadband power, which is visible at frequencies as low as ∼50 Hz. These results distinguish broadband high-gamma activity from gamma rhythms as an easily obtained and reliable electrophysiological index of neuronal firing near the microelectrode. Further, they highlight the importance of making a careful dissociation between gamma rhythms and spike-related transients that could be incorrectly decomposed as rhythms using traditional signal processing methods.

  1. Gamma ray observatory productivity showcase

    NASA Technical Reports Server (NTRS)

    Davis, R. L.; Molgaard, D. A.

    1985-01-01

    The Gamma Ray Observatory (GRO) Program has been proclaimed to be the showcase productivity program for NASA and TRW. Among the multiple disciplines of a large-scale program, there is opportunity and need for improved efficiency, effectiveness, and reduction in the cost of doing business. The efforts and tools that will or have been implemented to achieve this end are described. Since the GRO Program is mainly an engineering program with the build of one satellite, the primary emphasis is placed on improving the efficiency and quality of management and engineering.

  2. Using (d,p{gamma}) as a surrogate reaction for (n,{gamma})

    SciTech Connect

    Hatarik, R.; Cizewski, J. A.; Hatarik, A. M.; O'Malley, P. D.; Bernstein, L. A.; Burke, J. T.; Bleuel, D. L.; Lesher, S. R.; Gibelin, J.; Phair, L.; Swan, T.

    2009-01-28

    To benchmark the validity of using the (d,p{gamma}) reaction as a surrogate for (n,{gamma}), the {sup 171,173}Yb(d,p{gamma}) reactions were measured with the goal to reproduce the known neutron capture cross section ratio of these nuclei. Preliminary surrogate results reproduced the measured values within 15%.

  3. Implications of Gamma-Ray Transparency Constraints in Blazars: Minimum Distances and Gamma-Ray Collimation

    NASA Technical Reports Server (NTRS)

    Becker, Peter A.; Kafatos, Menas

    1995-01-01

    We develop a general expression for the gamma - gamma absorption coefficient, alpha(sub gamma(gamma)) for gamma-rays propagating in an arbitrary direction at an arbitrary point in space above an X-ray-emitting accretion disk. The X-ray intensity is assumed to vary as a power law in energy and radius between the outer disk radius, R(sub 0), and the inner radius, R(sub ms) which is the radius of marginal stability for a Schwarzschild black hole. We use our result for alpha(sub gamma(gamma)) to calculate the gamma - gamma optical depth, tau(sub gamma(gamma)) for gamma - rays created at height z and propagating at angle Phi relative to the disk axis, and we show that for Phi = 0 and z greater than or approx equal to R(sub 0), tau(sub gamma(gamma)) proportional to Epsilon(sup alpha)z(sup -2(alpha) - 3), where alpha is the X-ray spectral index and Epsilon is the gamma - ray energy. As an application, we use our formalism to compute the minimum distance between the central black hole and the site of production of the gamma-rays detected by EGRET during the 1991 June flare of 3C 279. In order to obtain an upper limit, we assume that all of the X-rays observed contemporaneously by Ginga were emitted by the disk. Our results suggest that the observed gamma - rays may have originated within less than or approx equal to 45 GM/sq c from a black hole of mass greater than or approx equal to 10(exp 9) solar mass, perhaps in active plasma located above the central funnel of the accretion disk. This raises the possibility of establishing a direct connection between the production of the observed gamma - rays and the accretion of material onto the black hole. We also consider the variation of the optical depth as a function of the angle of propagation Phi. Our results indicate that the "focusing" of the gamma - rays along the disk axis due to pair production is strong enough to explain the observed degree of alignment in blazar sources. If the gamma - rays are produced isotropically

  4. Measurements of Branching Fractions for B+ -> rho+ gamma, B0 -> rho0 gamma, and B0 -> omega gamma

    SciTech Connect

    Aubert, B

    2008-08-15

    The authors present branching fraction measurements for the radiative decays B{sup +} {yields} {rho}{sup +}{gamma}, B{sup 0} {yields} {rho}{sup 0}{gamma}, and B{sup 0} {yields} {omega}{gamma}. The analysis is based on a data sample of 465 million B{bar B} events collected with the BABAR detector at the PEP-II asymmetric-energy B Factory located at the Stanford Linear Accelerator Center (SLAC). They find {Beta}(B{sup +} {yields} {rho}{sup +}{gamma}) = (1.20{sub -0.37}{sup +0.42} {+-} 0.20) x 10{sup -6}, {Beta}(B{sup 0} {yields} {rho}{sup 0}{gamma}) = (0.97{sub -0.22}{sup +0.24} {+-} 0.06) x 10{sup -6}, and a 90% C.L. upper limit {Beta}(B{sup 0} {yields} {omega}{gamma}) < 0.9 x 10{sup -6}, where the first error is statistical and the second is systematic. They also measure the isospin-violating quantity {Lambda}(B{sup +} {yields} {rho}{sup +}{gamma})/2{Lambda}(B{sup 0} {yields} {rho}{sup 0}{gamma}) - 1 = -0.43{sub -0.22}{sup +0.25} {+-} 0.10.

  5. Supervised Gamma Process Poisson Factorization

    SciTech Connect

    Anderson, Dylan Zachary

    2015-05-01

    This thesis develops the supervised gamma process Poisson factorization (S- GPPF) framework, a novel supervised topic model for joint modeling of count matrices and document labels. S-GPPF is fully generative and nonparametric: document labels and count matrices are modeled under a uni ed probabilistic framework and the number of latent topics is controlled automatically via a gamma process prior. The framework provides for multi-class classification of documents using a generative max-margin classifier. Several recent data augmentation techniques are leveraged to provide for exact inference using a Gibbs sampling scheme. The first portion of this thesis reviews supervised topic modeling and several key mathematical devices used in the formulation of S-GPPF. The thesis then introduces the S-GPPF generative model and derives the conditional posterior distributions of the latent variables for posterior inference via Gibbs sampling. The S-GPPF is shown to exhibit state-of-the-art performance for joint topic modeling and document classification on a dataset of conference abstracts, beating out competing supervised topic models. The unique properties of S-GPPF along with its competitive performance make it a novel contribution to supervised topic modeling.

  6. The virtual gamma camera room.

    PubMed

    Penrose, J M; Trowbridge, E A; Tindale, W B

    1996-05-01

    The installation of a gamma camera is time-consuming and costly and, once installed, the camera position is unlikely to be altered during its working life. Poor choice of camera position therefore has long-term consequences. Additional equipment such as collimators and carts, the operator's workstation and wall-mounted display monitors must also be situated to maximize access and ease of use. The layout of a gamma camera room can be optimized prior to installation by creating a virtual environment. Super-Scape VRT software running on an upgraded 486 PC microprocessor was used to create a 'virtual camera room'. The simulation included an operator's viewpoint and a controlled tour of the room. Equipment could be repositioned as required, allowing potential problems to be identified at the design stage. Access for bed-ridden patients, operator ergonomics, operator and patient visibility were addressed. The display can also be used for patient education. Creation of a virtual environment is a valuable tool which allows different camera systems to be compared interactively in terms of dimensions, extent of movement and use of a defined space. Such a system also has applications in radiopharmacy design and simulation.

  7. Gamma-ray burst populations

    NASA Astrophysics Data System (ADS)

    Virgili, Francisco Javier

    Over the last fifty years the field of gamma-ray bursts has shown incredible growth, but the amassing of data has also left observers and theorists alike wondering about some of the basic questions surrounding these phenomena. Additionally, these events show remarkable individuality and extrema, ranging in redshift throughout the observable universe and over ten orders of magnitude in energy. This work focuses on analyzing groups of bursts that are different from the general trend and trying to understand whether these bursts are from different intrinsic populations and if so, what can be said about their progenitors. This is achieved through numerical Monte Carlo simulations and statistical inference in conjunction with current GRB observations. Chapter 1 gives a general introduction of gamma-ray burst theory and observations in a semi-historical context. Chapter 2 provides an introduction to the theory and practical issues surrounding the numerical simulations and statistics. Chapters 3--5 are each dedicated to a specific problem relating to a different type of GRB population: high-luminosity v. low-luminosity bursts, constraints from high-redshift bursts, and Type I v. Type II bursts. Chapter 6 follows with concluding remarks.

  8. Dark gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Brdar, Vedran; Kopp, Joachim; Liu, Jia

    2017-03-01

    Many theories of dark matter (DM) predict that DM particles can be captured by stars via scattering on ordinary matter. They subsequently condense into a DM core close to the center of the star and eventually annihilate. In this work, we trace DM capture and annihilation rates throughout the life of a massive star and show that this evolution culminates in an intense annihilation burst coincident with the death of the star in a core collapse supernova. The reason is that, along with the stellar interior, also its DM core heats up and contracts, so that the DM density increases rapidly during the final stages of stellar evolution. We argue that, counterintuitively, the annihilation burst is more intense if DM annihilation is a p -wave process than for s -wave annihilation because in the former case, more DM particles survive until the supernova. If among the DM annihilation products are particles like dark photons that can escape the exploding star and decay to standard model particles later, the annihilation burst results in a flash of gamma rays accompanying the supernova. For a galactic supernova, this "dark gamma-ray burst" may be observable in the Čerenkov Telescope Array.

  9. EML HASL-300 Method Ga-01-R: Gamma Radioassay

    EPA Pesticide Factsheets

    This method uses gamma spectrometry for measurement of gamma photons emitted from radionuclides. Samples are placed into a standard geometry for gamma counting, typically using an high purity Germanium [HP(Ge)] detector.

  10. First results from ASP on resonance production in. gamma gamma. interactions

    SciTech Connect

    Roe, N.

    1988-05-01

    The reaction e/sup +/e/sup -//yields/e/sup +/e/sup -//gamma/sup *//gamma/sup *///yields/(e/sup +/e/sup -/)/eta/, with subsequent decay of the /eta/ into two photons, has been observed with the ASP detector at the PEP e/sup +/e/sup -/ storage ring at /radical/ s=29 GeV. A measurement of the radiative width of the /eta/ yields the preliminary result /Gamma/(/eta//yields//gamma//gamma/) = .489 /+-/ .009 /+-/ .055 keV. Evidence for the production of the /eta/' with decay into two photons has also been observed.

  11. Very high-energy gamma rays from gamma-ray bursts.

    PubMed

    Chadwick, Paula M

    2007-05-15

    Very high-energy (VHE) gamma-ray astronomy has undergone a transformation in the last few years, with telescopes of unprecedented sensitivity having greatly expanded the source catalogue. Such progress makes the detection of a gamma-ray burst at the highest energies much more likely than previously. This paper describes the facilities currently operating and their chances for detecting gamma-ray bursts, and reviews predictions for VHE gamma-ray emission from gamma-ray bursts. Results to date are summarized.

  12. Gamma ray astronomy from satellites and balloons

    NASA Technical Reports Server (NTRS)

    Schoenfelder, V.

    1986-01-01

    A survey is given of gamma ray astronomy topics presented at the Cosmic Ray Conference. The major conclusions at the Cosmic Ray Conference in the field of gamma ray astronomy are given. (1) MeV-emission of gamma-ray bursts is a common feature. Variations in duration and energy spectra from burst to burst may explain the discrepancy between the measured log N - log S dependence and the observed isotropy of bursts. (2) The gamma-ray line at 1.809 MeV from Al(26) is the first detected line from a radioactive nucleosynthesis product. In order to understand its origin it will be necessary to measure its longitude distribution in the Milky Way. (3) The indications of a gamma-ray excess found from the direction of Loop I is consistent with the picture that the bulk of cosmic rays below 100 GeV is produced in galactic supernova remnants. (4) The interpretation of the large scale distribution of gamma rays in the Milky Way is controversial. At present an extragalactic origin of the cosmic ray nuclei in the GeV-range cannot be excluded from the gamma ray data. (5) The detection of MeV-emission from Cen A is a promising step towards the interesting field of extragalactic gamma ray astronomy.

  13. Multiple Scatters in Single Site Gamma Backgrounds

    SciTech Connect

    Brodsky, J. P.

    2016-09-16

    nEXO aims to reduce its gamma backgrounds by taking advantage of the fact that a large number of gammas that would otherwise be backgrounds will undergo multiple compton scattering in the TPC and produce spatially distinct signals. These multi-sited (MS) events can be excluded from the 0νββ search.

  14. Scanning Gamma Ray Densitometer System for Detonations.

    DTIC Science & Technology

    in loaded detonators and delays. The 317 KEV gamma rays from an Ir192 source were collimated into a beam of 0.002 by 0.100 inch. A scanning system...minus 3%. With Ir192 , density measurements on NOL-130 were reproduced to plus or minus 5%, and on RDX to plus or minus 16%. Based on gamma ray

  15. The History of Gamma-Ray Astronomy

    NASA Astrophysics Data System (ADS)

    Schönfelder, V.

    An overview of the history of gamma-ray astronomy is given starting with predictions in the 1950's and first detections in the 1960's. Tremendous efforts have been made since then, with exciting discoveries, which finally culminated in the ``Golden Age'' of gamma-ray astronomy which we are presently experiencing.

  16. The history of gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Schönfelder, V.

    2002-07-01

    An overview of the history of gamma-ray astronomy is given starting with predictions in the 1950s and first detections in the 1960s. Tremendous efforts have been made since then, with exciting discoveries, which finally culminated in the ``Golden Age'' of gamma-ray astronomy which we are presently experiencing.

  17. Study of gamma-ray strength functions

    SciTech Connect

    Gardner, D.G.; Gardner, M.A.; Dietrich, F.S.

    1980-08-07

    The use of gamma-ray strength function systematics to calculate neutron capture cross sections and capture gamma-ray spectra is discussed. The ratio of the average capture width, GAMMA/sub ..gamma../-bar, to the average level spacing, D/sub obs/, both at the neutron separation energy, can be derived from such systematics with much less uncertainty than from separate systematics for values of GAMMA/sub ..gamma../-bar and D/sub obs/. In particular, the E1 gamma-ray strength function is defined in terms of the giant dipole resonance (GDR). The GDR line shape is modeled with the usual Lorentzian function and also with a new energy-dependent, Breit-Wigner (EDBW) function. This latter form is further parameterized in terms of two overlapping resonances, even for nuclei where photonuclear measurements do not resolve two peaks. In the mass ranges studied, such modeling is successful for all nuclei away from the N = 50 closed neutron shell. Near the N = 50 shell, a one-peak EDBW appears to be more appropriate. Examples of calculated neutron capture excitation functions and capture gamma-ray spectra using the EDBW form are given for target nuclei in the mass-90 region and also in the Ta-Au mass region. 20 figures.

  18. Shielding for beta-gamma radiation.

    PubMed

    Fletcher, J J

    1993-06-01

    The build-up factor, B, for lead was expressed as a polynominal cubic function of the relaxation length, mu x, and incorporated in a "general beta-gamma shielding equation." A computer program was written to determine shielding thickness for polyenergetic beta-gamma sources without resorting to the conventional "add-one-HVL" method.

  19. Gamma-ray spectral analysis algorithm library

    SciTech Connect

    Egger, A. E.

    2013-05-06

    The routines of the Gauss Algorithms library are used to implement special purpose products that need to analyze gamma-ray spectra from Ge semiconductor detectors as a part of their function. These routines provide the ability to calibrate energy, calibrate peakwidth, search for peaks, search for regions, and fit the spectral data in a given region to locate gamma rays.

  20. ASTRONOMY: Neighborhood Gamma Ray Burst Boosts Theory.

    PubMed

    Schilling, G

    2000-07-07

    Titanic explosions that emit powerful flashes of energetic gamma rays are one of astronomy's hottest mysteries. Now an analysis of the nearest gamma ray burst yet detected has added weight to the popular theory that they are expelled during the death throes of supermassive stars.

  1. Genetics Home Reference: mucolipidosis III gamma

    MedlinePlus

    ... time. People with mucolipidosis III gamma often have heart valve abnormalities and mild clouding of the clear covering ... III Gamma MedlinePlus Encyclopedia: Cloudy Cornea MedlinePlus Encyclopedia: Heart Valves General Information from MedlinePlus (5 links) Diagnostic Tests ...

  2. HIGGS PHYSICS WITH A GAMMA GAMMA COLLIDER BASED ON CLIC 1*.

    SciTech Connect

    ASNER,D.; BURKHARDT,H.; DE ROECK,A.; ELLIS,J.; GRONBERG,J.; HEINEMEYER,S.; SCHMITT,M.; SCHULTE,D.; VELASCO,M.; ZIMMERMAN,F.

    2001-11-01

    We present the machine parameters and physics capabilities of the CLIC Higgs Experiment (CLICHE), a low-energy {gamma}{gamma} collider based on CLIC 1, the demonstration project for the higher-energy two-beam accelerator CLIC. CLICHE is conceived as a factory capable of producing around 20,000 light Higgs bosons per year. We discuss the requirements for the CLIC 1 beams and a laser backscattering system capable of producing a {gamma}{gamma} total (peak) luminosity of 2.0 (0.36) x 10{sup 34} cm{sup -2} s{sup -1} with E{sub CM}({gamma}{gamma}) 115 GeV. We show how CLICHE could be used to measure accurately the mass, {bar b}b, WW and {gamma}{gamma} decays of a light Higgs boson. We illustrate how these measurements may distinguish between the Standard Model Higgs boson and those in supersymmetric and more general two-Higgs-doublet models, complementing the measurements to be made with other accelerators. We also comment on other prospects in {gamma}{gamma} and e{sup -}{gamma} physics with CLICHE.

  3. Software tool for xenon gamma-ray spectrometer control

    NASA Astrophysics Data System (ADS)

    Chernysheva, I. V.; Novikov, A. S.; Shustov, A. E.; Dmitrenko, V. V.; Pyae Nyein, Sone; Petrenko, D.; Ulin, S. E.; Uteshev, Z. M.; Vlasik, K. F.

    2016-02-01

    Software tool "Acquisition and processing of gamma-ray spectra" for xenon gamma-ray spectrometers control was developed. It supports the multi-windows interface. Software tool has the possibilities for acquisition of gamma-ray spectra from xenon gamma-ray detector via USB or RS-485 interfaces, directly or via TCP-IP protocol, energy calibration of gamma-ray spectra, saving gamma-ray spectra on a disk.

  4. Neutron monitoring systems including gamma thermometers and methods of calibrating nuclear instruments using gamma thermometers

    DOEpatents

    Moen, Stephan Craig; Meyers, Craig Glenn; Petzen, John Alexander; Foard, Adam Muhling

    2012-08-07

    A method of calibrating a nuclear instrument using a gamma thermometer may include: measuring, in the instrument, local neutron flux; generating, from the instrument, a first signal proportional to the neutron flux; measuring, in the gamma thermometer, local gamma flux; generating, from the gamma thermometer, a second signal proportional to the gamma flux; compensating the second signal; and calibrating a gain of the instrument based on the compensated second signal. Compensating the second signal may include: calculating selected yield fractions for specific groups of delayed gamma sources; calculating time constants for the specific groups; calculating a third signal that corresponds to delayed local gamma flux based on the selected yield fractions and time constants; and calculating the compensated second signal by subtracting the third signal from the second signal. The specific groups may have decay time constants greater than 5.times.10.sup.-1 seconds and less than 5.times.10.sup.5 seconds.

  5. PPAR-gamma in the Cardiovascular System.

    PubMed

    Duan, Sheng Zhong; Ivashchenko, Christine Y; Usher, Michael G; Mortensen, Richard M

    2008-01-01

    Peroxisome proliferator-activated receptor-gamma (PPAR-gamma), an essential transcriptional mediator of adipogenesis, lipid metabolism, insulin sensitivity, and glucose homeostasis, is increasingly recognized as a key player in inflammatory cells and in cardiovascular diseases (CVD) such as hypertension, cardiac hypertrophy, congestive heart failure, and atherosclerosis. PPAR-gamma agonists, the thiazolidinediones (TZDs), increase insulin sensitivity, lower blood glucose, decrease circulating free fatty acids and triglycerides, lower blood pressure, reduce inflammatory markers, and reduce atherosclerosis in insulin-resistant patients and animal models. Human genetic studies on PPAR-gamma have revealed that functional changes in this nuclear receptor are associated with CVD. Recent controversial clinical studies raise the question of deleterious action of PPAR-gamma agonists on the cardiovascular system. These complex interactions of metabolic responsive factors and cardiovascular disease promise to be important areas of focus for the future.

  6. Visual awareness, emotion, and gamma band synchronization.

    PubMed

    Luo, Qian; Mitchell, Derek; Cheng, Xi; Mondillo, Krystal; Mccaffrey, Daniel; Holroyd, Tom; Carver, Frederick; Coppola, Richard; Blair, James

    2009-08-01

    What makes us become aware? A popular hypothesis is that if cortical neurons fire in synchrony at a certain frequency band (gamma), we become aware of what they are representing. We tested this hypothesis adopting brain-imaging techniques with good spatiotemporal resolution and frequency-specific information. Specifically, we examined the degree to which increases in event-related synchronization (ERS) in the gamma band were associated with awareness of a stimulus (its detectability) and/or the emotional content of the stimulus. We observed increases in gamma band ERS within prefrontal-anterior cingulate, visual, parietal, posterior cingulate, and superior temporal cortices to stimuli available to conscious awareness. However, we also observed increases in gamma band ERS within the amygdala, visual, prefrontal, parietal, and posterior cingulate cortices to emotional relative to neutral stimuli, irrespective of their availability to conscious access. This suggests that increased gamma band ERS is related to, but not sufficient for, consciousness.

  7. Origin of the gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Vahia, M. N.; Rao, A. R.

    1988-12-01

    The authors establish a similarity between the gamma ray burst characteristics and solar hard X-ray flares. They show that all the temporal and spectral features observed in gamma ray bursts are also seen in solar hard X-ray flares. The only distinction is in the energy contents of the two. The authors suggest that the gamma-ray bursts originate from sources which have Sun like activity. Large scale Sun like activity has been observed in flare stars, RS CVn binaries and cataclysmic variables which are grouped together as the magnetically active stellar systems. The energetics of such systems is discussed and it is shown that these systems have enough energy to produce gamma-ray bursts. The authors then attempt positional identification between gamma-ray burst error boxes and the magnetically active stellar systems and find an association of 34 objects.

  8. Production of modified starches by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Kang, Il-Jun; Byun, Myung-Woo; Yook, Hong-Sun; Bae, Chun-Ho; Lee, Hyun-Soo; Kwon, Joong-Ho; Chung, Cha-Kwon

    1999-04-01

    As a new processing method for the production of modified starch, gamma irradiation and four kinds of inorganic peroxides were applied to commercial corn starch. The addition of inorganic peroxides without gamma irradiation or gamma irradiation without the addition of inorganic peroxides effectively decreased initial viscosity, but did not sufficiently keep viscosity stable. The combination of adding ammonium persulfate (APS) and gamma irradiation showed the lowest initial viscosity and the best stability out of the tested four kinds of inorganic peroxides. Among the tested mixing methods of APS, soaking was found to be more effective than dry blending or spraying. Therefore, the production of modified starch with low viscosity as well as with sufficient viscosity stability became feasible by the control of gamma irradiation dose levels and the amount of added APS to starch.

  9. Unveiling the secrets of gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Gomboc, Andreja

    2012-07-01

    Gamma Ray Bursts are unpredictable and brief flashes of gamma rays that occur about once a day in random locations in the sky. Since gamma rays do not penetrate the Earth's atmosphere, they are detected by satellites, which automatically trigger ground-based telescopes for follow-up observations at longer wavelengths. In this introduction to Gamma Ray Bursts we review how building a multi-wavelength picture of these events has revealed that they are the most energetic explosions since the Big Bang and are connected with stellar deaths in other galaxies. However, in spite of exceptional observational and theoretical progress in the last 15 years, recent observations raise many questions which challenge our understanding of these elusive phenomena. Gamma Ray Bursts therefore remain one of the hottest topics in modern astrophysics.

  10. Gamma cameras--state of the art.

    PubMed

    Zimmerman, R E

    1979-01-01

    The growth of nuclear medicine has paralleled the development and acceptance of gamma cameras, which are stationary instruments that produce an image of an isotope distribution. The most successful gamma camera is based on a large, single crystal of the scintillator sodium iodide coupled to an array of photomultiplier tubes and electronic networks to determine the location of a gamma ray. Current cameras are capable of spatial resolution of 4.0 mm or better. Other types of gamma cameras have been developed, including the multi-crystal camera and a limited number of instruments using gas detectors and semiconductor detectors. The scintillation type of gamma camera will continue to be the dominant camera for the next 5 to 10 years, and will continue to gradually improve. Most significant improvements will result from application of digital electronics to position circuits.

  11. Zapping Mars Rocks with Gamma Rays

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    1999-12-01

    Because we do not know what deadly microorganisms might be lurking inside samples returned from Mars, the samples will either have to be sterilized before release or kept in isolation until biological studies declare them safe. One way to execute microorganisms is with radiation, such as gamma rays. Although quite effective in snuffing out bacteria and viruses, gamma rays might also affect the mineralogical, chemical, and isotopic compositions of the zapped rocks and soils. Carl Allen (Lockheed Martin Space Operations, Houston) and a team of 18 other analysts tested the effect of gamma rays on rock and mineral samples like those we expect on Mars. Except for some darkening of some minerals, high doses of gamma rays had no significant effect on the rocks, making gamma radiation a feasible option for sterilizing samples returned from Mars.

  12. Gamma interferon: a central mediator in atherosclerosis.

    PubMed

    Leon, M L Alfaro; Zuckerman, S H

    2005-10-01

    Atherosclerosis is a chronic inflammatory disease of the vasculature with lesions developing in the arterial wall, frequently in the coronary and carotid arteries. The interaction between macrophages and lymphocytes within the atherosclerotic lesion microenvironment exemplifies a site where both innate and adaptive immunity contribute towards disease progression. As gamma interferon (IFN-gamma), the classic macrophage activating factor, has been localized to atherosclerotic lesions, this review will focus on its contribution to plaque pathology and will finally consider how current therapies, as exemplified by HMG CoA reductase inhibitors or statins, may impact this process beyond lipid lowering, in part by inhibiting IFN-gamma dependent processes. IFN-gamma sources within the atheroma as well as receptors, signaling pathways and its effects on macrophages as well as on vascular smooth muscle and endothelial cells will be considered. Therapeutic interventions targeting molecular events associated with IFN-gamma signaling offer novel approaches to the treatment of atherosclerosis.

  13. Atmospheric gamma-ray and neutron flashes

    SciTech Connect

    Babich, L. P. Kudryavtsev, A. Yu. Kudryavtseva, M. L. Kutsyk, I. M.

    2008-01-15

    Gamma-ray pulses are calculated from 2D numerical simulations of an upward atmospheric discharge in a self-consistent electric field using the multigroup approach to the kinetics of relativistic runaway electrons (REs). Computed {gamma}-ray numbers and spectra are consistent with those of terrestrial {gamma}-ray flashes (TGFs) observed aboard spacecrafts. The RE flux is concentrated mainly within the domain of the Blue Jet fluorescence. This confirms that exactly the domain adjacent to a thundercloud is the source of the observed {gamma}-ray flashes. The yield of photonuclear neutrons is calculated. One {gamma}-ray pulse generates {approx}10{sup 14}-10{sup 15} neutrons. The possibility of the direct deposition of REs to the detector readings and the origin of the lightning-advanced TGFs are discussed.

  14. The EGRET high energy gamma ray telescope

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.; Bertsch, D. L.; Fichtel, C. E.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.; Mayer-Hasselwander, H. A.

    1992-01-01

    The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (GRO) is sensitive in the energy range from about 20 MeV to about 30,000 MeV. Electron-positron pair production by incident gamma photons is utilized as the detection mechanism. The pair production occurs in tantalum foils interleaved with the layers of a digital spark chamber system; the spark chamber records the tracks of the electron and positron, allowing the reconstruction of the arrival direction of the gamma ray. If there is no signal from the charged particle anticoincidence detector which surrounds the upper part of the detector, the spark chamber array is triggered by two hodoscopes of plastic scintillators. A time of flight requirement is included to reject events moving backward through the telescope. The energy of the gamma ray is primarily determined by absorption of the energies of the electron and positron in a 20 cm deep NaI(Tl) scintillator.

  15. Future Missions for Gamma-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Meegan, Charles; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Gamma-ray astronomy has made great advances in recent years, due largely to the recently completed 9-year mission of the Compton Gamma Ray Observatory. In this talk I will give an overview of what advances we may expect in the near future, with particular emphasis on earth-orbiting missions scheduled for flight within the next 5 years. Two missions, the High Energy Transient Explorer and Swift, will provide important new information on the sources of gamma-ray bursts. The Gamma-Ray Large Area Space Telescope will investigate high energy emission from a wide variety of sources, including active galaxies and gamma-ray pulsars. The contributions of ground-based and multiwavelength observations will also be addressed.

  16. Calculations of g{alpha}0{omega}{gamma}, gf0{omega}{gamma}, g{alpha}0{rho}{gamma} and gf0{rho}{gamma} Coupling Constants in QCD Sum Rules

    SciTech Connect

    Aydin, C.; Bayar, M.; Yilmaz, A. H.

    2007-04-23

    The coupling constants of {alpha}0 {yields} {omega}{gamma}, f0 {yields} {omega}{gamma}, {alpha}0 {yields} {rho}{gamma}, and f0 {yields} {rho}{gamma} are calculated using 3-point QCD sum rules. We estimate the coupling constants g{alpha}0{omega}{gamma}, gf0{omega}{gamma}, g{alpha}0{rho}{gamma} and gf0{rho}{gamma} which are an essential ingredient in the analysis of physical processes involving isoscalar f0(980) and isovector {alpha}0(980) mesons.

  17. Method of Incident Low-Energy Gamma-Ray Direction Reconstruction in GAMMA-400 Gamma-Ray Space Telescope

    NASA Astrophysics Data System (ADS)

    Kheymits, M. D.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Galper, A. M.; Zverev, V. G.; Leonov, A. A.; Suchkov, S. I.; Topchiev, N. P.; Yurkin, Y. T.

    Gamma-telescope GAMMA-400 is designed to measure fluxes of γ-rays and the electron-positron cosmic ray component possibly associated with dark matter particles annihilation or decay; and to search for and study in detail discrete γ-ray sources, to investigate the energy spectra of Galactic and extragalactic diffuse γ-rays, and to study γ-ray bursts (GRB) and γ-rays from the active Sun. GAMMA-400 gamma-ray space-based telescope scientific goals require fine angular resolution. GAMMA-400 is the pair production telescope. In the converter-tracker the incident gamma-quantum convert into electron-positron pair in the tungsten layer and then the tracks are registered by silicon-strip position-sensitive detectors. Multiple scattering processes become a significant obstacle in the incident gamma direction reconstruction for energies below several GeV. The method of utilising this process to improve the resolution is proposed in the presented work.

  18. Gamma Rays from Classical Novae

    NASA Technical Reports Server (NTRS)

    1997-01-01

    NASA at the University of Chicago, provided support for a program of theoretical research into the nature of the thermonuclear outbursts of the classical novae and their implications for gamma ray astronomy. In particular, problems which have been addressed include the role of convection in the earliest stages of nova runaway, the influence of opacity on the characteristics of novae, and the nucleosynthesis expected to accompany nova outbursts on massive Oxygen-Neon-Magnesium (ONeMg) white dwarfs. In the following report, I will identify several critical projects on which considerable progress has been achieved and provide brief summaries of the results obtained:(1) two dimensional simulation of nova runaway; (2) nucleosynthesis of nova modeling; and (3) a quasi-analytic study of nucleosynthesis in ONeMg novae.

  19. The Portuguese gamma irradiation facility

    NASA Astrophysics Data System (ADS)

    Mendes, C. M.; Almeida, J. C.; Botelho, M. L.; Cavaco, M. C.; Almeida-Vara, E.; Andrade, M. E.

    A Gamma Radiation Facility was built up in the National Laboratory of Industrial Technology and Engineering (LNETI), Lisbon, Portugal. This plant (UTR GAMA-Pi) is a Cobalt-60 dry storage continuous facility with a nominal capacity of 1.5X10 16 Bq. The initial activity is 1.1X10 16 Bq and the troughput capacity 10 3 ton/year for product with a bulk density of 0.2 g/cm 3 treated with a minimum absorbed dose of 25 kGy. Complementary control devices were installed: ventilation system, closed water refrigeration circuit, internal TV system, detection and extinction fire system and emergency power group. It must be emphasized that the best attention was given to the conception and efficiency of the interlock safety systems. This facility will be utilized mainly for radiosterilization of medical articles and decontamination of wine cork stoppers.

  20. Gamma-insensitive optical sensor

    DOEpatents

    Kruger, H.W.

    1994-03-15

    An ultraviolet/visible/infrared gamma-insensitive gas avalanche focal plane array is described comprising a planar photocathode and a planar anode pad array separated by a gas-filled gap and across which is applied an electric potential. Electrons ejected from the photocathode are accelerated sufficiently between collisions with the gas molecules to ionize them, forming an electron avalanche. The gap acts like a proportional counter. The array of anode pad are mounted on the front of an anode plate and are connected to matching contact pads on the back of the anode via feed through wires. Connection of the anode to signal processing electronics is made from the contact pads using standard indium bump techniques, for example. 6 figures.

  1. Gamma Knife Radiosurgery for Acromegaly

    PubMed Central

    Rolston, John D.; Blevins, Lewis S.

    2012-01-01

    Acromegaly is debilitating disease occasionally refractory to surgical and medical treatment. Stereotactic radiosurgery, and in particular Gamma Knife surgery (GKS), has proven to be an effective noninvasive adjunct to traditional treatments, leading to disease remission in a substantial proportion of patients. Such remission holds the promise of eliminating the need for expensive medications, along with side effects, as well as sparing patients the damaging sequelae of uncontrolled acromegaly. Numerous studies of radiosurgical treatments for acromegaly have been carried out. These illustrate an overall remission rate over 40%. Morbidity from radiosurgery is infrequent but can include cranial nerve palsies and hypopituitarism. Overall, stereotactic radiosurgery is a promising therapy for patients with acromegaly and deserves further study to refine its role in the treatment of affected patients. PMID:22518132

  2. Gamma-4 electrophysical facility project

    NASA Astrophysics Data System (ADS)

    Zavyalov, N. V.; Gordeev, V. S.; Punin, V. T.; Grishin, A. V.; Nazarenko, S. T.; Pavlov, V. S.; Demanov, V. A.; Shikhanova, T. F.; Kalashnikov, D. A.; Kozachek, A. V.; Glushkov, S. L.; Strabykin, K. V.; Puchagin, S. Yu.; Mansurov, D. O.; Mironychev, B. P.; Maiorov, R. A.; Maiornikova, V. L.

    2015-01-01

    The paper presents the Gamma-4 four-module electrophysical facility project developed for radiation physics research. For this facility, we have developed and tested a typical module which, with a matched load, generates an electrical pulse with voltage and current amplitudes of up to 2 MV and 750 kA, respectively, and with a half-height duration of 60 ns. 700 shots were performed which conformed the operating parameters and reliability of the module. Layouts of the facility for the modes of synchronous (with accuracy of ±3 ns) operation of the modules with vacuum electron diodes and with a current summator to generate soft x-ray pulses have been developed.

  3. Gamma-insensitive optical sensor

    DOEpatents

    Kruger, Hans W.

    1994-01-01

    An ultra-violet/visible/infra-red gamma-insensitive gas avalanche focal plane array comprising a planar photocathode and a planar anode pad array separated by a gas-filled gap and across which is applied an electric potential. Electrons ejected from the photocathode are accelerated sufficiently between collisions with the gas molecules to ionize them, forming an electron avalanche. The gap acts like a proportional counter. The array of anode pad are mounted on the front of an anode plate and are connected to matching contact pads on the back of the anode via feed through wires. Connection of the anode to signal processing electronics is made from the contact pads using standard indium bump techniques, for example.

  4. Durability Assessment of Gamma Tial

    NASA Technical Reports Server (NTRS)

    Draper, Susan L.; Lerch, Bradley A.; Pereira, J. Michael; Miyoshi, Kazuhisa; Arya, Vinod K.; Zhuang, Wyman

    2004-01-01

    Gamma TiAl was evaluated as a candidate alloy for low-pressure turbine blades in aeroengines. The durability of g-TiAl was studied by examining the effects of impact or fretting on its fatigue strength. Cast-to-size Ti-48Al-2Cr-2Nb was studied in impact testing with different size projectiles at various impact energies as the reference alloy and subsequently fatigue tested. Impacting degraded the residual fatigue life. However, under the ballistic impact conditions studied, it was concluded that the impacts expected in an aeroengine would not result in catastrophic damage, nor would the damage be severe enough to result in a fatigue failure under the anticipated design loads. In addition, other gamma alloys were investigated including another cast-to-size alloy, several cast and machined specimens, and a forged alloy. Within this Ti-48-2-2 family of alloys aluminum content was also varied. The cracking patterns as a result of impacting were documented and correlated with impact variables. The cracking type and severity was reasonably predicted using finite element models. Mean stress affects were also studied on impact-damaged fatigue samples. The fatigue strength was accurately predicted based on the flaw size using a threshold-based, fracture mechanics approach. To study the effects of wear due to potential applications in a blade-disk dovetail arrangement, the machined Ti-47-2-2 alloy was fretted against In-718 using pin-on-disk experiments. Wear mechanisms were documented and compared to those of Ti-6Al-4V. A few fatigue samples were also fretted and subsequently fatigue tested. It was found that under the conditions studied, the fretting was not severe enough to affect the fatigue strength of g-TiAl.

  5. A new measurement of the rare decay eta -> pi^0 gamma gamma with the Crystal Ball/TAPS detectors at the Mainz Microtron

    SciTech Connect

    Nefkens, B M; Prakhov, S; Aguar-Bartolom��, P; Annand, J R; Arends, H J; Bantawa, K; Beck, R; Bekrenev, V; Bergh��user, H; Braghieri, A; Briscoe, W J; Brudvik, J; Cherepnya, S; Codling, R F; Collicott, C; Costanza, S; Danilkin, I V; Denig, A; Demissie, B; Dieterle, M; Downie, E J; Drexler, P; Fil'kov, L V; Fix, A; Garni, S; Glazier, D I; Gregor, R; Hamilton, D; Heid, E; Hornidge, D; Howdle, D; Jahn, O; Jude, T C; Kashevarov, V L; K��ser, A; Keshelashvili, I; Kondratiev, R; Korolija, M; Kotulla, M; Koulbardis, A; Kruglov, S; Krusche, B; Lisin, V; Livingston, K; MacGregor, I J; Maghrbi, Y; Mancel, J; Manley, D M; McNicoll, E F; Mekterovic, D; Metag, V; Mushkarenkov, A; Nikolaev, A; Novotny, R; Oberle, M; Ortega, H; Ostrick, M; Ott, P; Otte, P B; Oussena, B; Pedroni, P; Polonski, A; Robinson, J; Rosner, G; Rostomyan, T; Schumann, S; Sikora, M H; Starostin, A; Strakovsky, I I; Strub, T; Suarez, I M; Supek, I; Tarbert, C M; Thiel, M; Thomas, A; Unverzagt, M; Watts, D P; Werthmueller, D; Witthauer, L

    2014-08-01

    A new measurement of the rare, doubly radiative decay eta->pi^0 gamma gamma was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the dependence of the partial decay width, Gamma(eta->pi^0 gamma gamma), on the two-photon invariant mass squared, m^2(gamma gamma), as well as a new, more precise value for the decay width, Gamma(eta->pi^0 gamma gamma) = (0.33+/-0.03_tot) eV, are based on analysis of 1.2 x 10^3 eta->pi^0 gamma gamma decays from a total of 6 x 10^7 eta mesons produced in the gamma p -> eta p reaction. The present results for dGamma(eta->pi^0 gamma gamma)/dm^2(gamma gamma) are in good agreement with previous measurements and recent theoretical calculations for this dependence.

  6. Interpretations and implications of gamma ray lines from solar flares, the galactic center in gamma ray transients

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1980-01-01

    Observations and theories of astrophysical gamma ray line emission are reviewed and prospects for future observations by the spectroscopy experiments on the planned Gamma Ray Observatory are discussed.

  7. Comparison of gamma-gamma Phase Coarsening Responses of Three Powder Metal Disk Superalloys

    NASA Technical Reports Server (NTRS)

    Gabb, T. P.; Gayda, J.; Johnson, D. F.; MacKay, R. A.; Rogers, R. B.; Sudbrack, C. K.; Garg, A.; Locci, I. E.; Semiatin, S. L.; Kang, E.

    2016-01-01

    The phase microstructures of several powder metal (PM) disk superalloys were quantitatively evaluated. Contents, chemistries, and lattice parameters of gamma and gamma strengthening phase were determined for conventionally heat treated Alloy 10, LSHR, and ME3 superalloys, after electrolytic phase extractions. Several of long term heat treatments were then performed, to allow quantification of the precipitation, content, and size distribution of gamma at a long time interval to approximate equilibrium conditions. Additional coarsening heat treatments were performed at multiple temperatures and shorter time intervals, to allow quantification of the precipitation, contents and size distributions of gamma at conditions diverging from equilibrium. Modest differences in gamma and gamma lattice parameters and their mismatch were observed among the alloys, which varied with heat treatment. Yet, gamma coarsening rates were very similar for all three alloys in the heat treatment conditions examined. Alloy 10 had higher gamma dissolution and formation temperatures than LSHR and ME3, but a lower lattice mismatch, which was slightly positive for all three alloys at room temperature. The gamma precipitates of Alloy 10 appeared to remain coherent at higher temperatures than for LSHR and ME3. Higher coarsening rates were observed for gamma precipitates residing along grain boundaries than for those within grains in all three alloys, during slow-moderate quenching from supersolvus solution heat treatments, and during aging at temperatures of 843 C and higher.

  8. Quantitative comparison of 3D and 2.5D gamma analysis: introducing gamma angle histograms

    NASA Astrophysics Data System (ADS)

    Sa'd, M. Al; Graham, J.; Liney, G. P.; Moore, C. J.

    2013-04-01

    Comparison of dose distributions using the 3D gamma method is anticipated to provide better indicators for the quality assurance process than the 2.5D (stacked 2D slice-by-slice) gamma calculation, especially for advanced radiotherapy technologies. This study compares the accuracy of the 3D and 2.5D gamma calculation methods. 3D and 2.5D gamma calculations were carried out on four reference/evaluation 3D dose sample pairs. A number of analysis methods were used, including average gamma and gamma volume histograms. We introduce the concept of gamma-angle histograms. Noise sensitivity tests were also performed using two different noise models. The advantage of the 3D gamma method showed up as a higher proportion of points passing the tolerance criteria of 3% dose difference and 3 mm distance-to-agreement (DTA), with considerably lower average gamma values, a lower influence of the DTA criterion, and a higher noise tolerance. The 3D gamma approach is more reliable than the 2.5D approach in terms of providing comprehensive quantitative results, which are needed in quality assurance procedures for advanced radiotherapy methods.

  9. Gamma-Ray Burst Physics with GLAST

    SciTech Connect

    Omodei, N.; /INFN, Pisa

    2006-10-06

    The Gamma-ray Large Area Space Telescope (GLAST) is an international space mission that will study the cosmos in the energy range 10 keV-300 GeV, the upper end of which is one of the last poorly observed region of the celestial electromagnetic spectrum. The ancestor of the GLAST/LAT was the Energetic Gamma Ray Experiment Telescope (EGRET) detector, which flew onboard the Compton Gamma Ray Observatory (CGRO). The amount of information and the step forward that the high energy astrophysics made thanks to its 9 years of observations are impressive. Nevertheless, EGRET uncovered the tip of the iceberg, raising many questions, and it is in the light of EGRET's results that the great potential of the next generation gamma-ray telescope can be appreciated. GLAST will have an imaging gamma-ray telescope, the Large Area Telescope (LAT) vastly more capable than instruments own previously, as well as a secondary instrument, the GLAST Bursts Monitor, or GBM, to augment the study of gamma-ray bursts. Gamma-Ray Bursts (GRBs) science is one of the most exciting challenges for the GLAST mission, exploring the high energy emission of one of the most intense phenomena in the sky, shading light on various problems: from the acceleration of particles to the emission processes, to more exotic physics like Quantum Gravity effect. In this paper we report the work done so far in the simulation development as well as the study of the LAT sensitivity to GRB.

  10. Python in gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Deil, Christoph Deil

    2016-03-01

    Gamma-ray astronomy is a relatively new window on the cosmos. The first source detected from the ground was the Crab nebula, seen by the Whipple telescope in Arizona in 1989. Today, about 150 sources have been detected at TeV energies using gamma-ray telescopes from the ground such as H.E.S.S. in Namibia or VERITAS in Arizona, and about 3000 sources at GeV energies using the Fermi Gamma-ray Space Telescope. Soon construction will start for the Cherenkov Telescope Array (CTA), which will be the first ground-based gamma-ray telescope array operated as an open observatory, with a site in the southern and a second site in the northern hemisphere. In this presentation I will give a very brief introduction to gamma-ray astronomy and data analysis, as well as a short overview of the software used for the various missions. The main focus will be on recent attempts to build open-source gamma-ray software on the scientific Python stack and Astropy: ctapipe as a CTA Python pipeline prototype, Fermipy and the Fermi Science Tools for Fermi-LAT analysis, Gammapy as a community-developed gamma-ray Python package and naima as a non-thermal spectral modeling and fitting package.

  11. Gamma-Ray Emission from Microquasars

    NASA Astrophysics Data System (ADS)

    Kaufman Bernado, M. M.

    2005-04-01

    Microquasars, X-ray binary systems that generate relativistic jets, were discovered in our Galaxy in the last decade of the XXth century. Their name indicates that they are manifestations of the same physics as quasars but on a completely different scale. Parallel to this discovery, the EGRET instrument on board of the Compton Gamma Ray Observatory detected 271 point like gamma-ray sources 170 of which were not clearly identified with known objects. This marked the beginning of gamma-ray source population studies in the Galaxy. We present in this thesis models for gamma-ray production in microquasars with the aim to propose them as possible parent populations for different groups of EGRET unidentified sources. These models are developed for a variety of scenarios taking into account several possible combinations, i.e. black holes or neutron stars as the compact object, low mass or high mass stellar companions, as well as leptonic or hadronic gamma-ray production processes. We also show that the presented models for gamma-rays emitting microquasars can be used to explain observations from well known sources that are detected in energy ranges other than EGRET's. Finally, we include an alternative gamma-ray producing situation that does not involve microquasars but a specific unidentified EGRET source possibly linked to a magnetized accreting pulsar.

  12. Observations of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.

    1995-01-01

    Some basic observed properties of gamma-ray bursts are reviewed. Although some properties were known 25 years ago, new and more detailed observations have been made by the Compton Observatory in the past three years. The new observation with the greatest impact has been the observed isotropic distribution of bursts along with a deficiency of weak bursts which would be expected from a homogeneous burst distribution. This is not compatible with any known Galactic population of objects. Gamma-ray bursts show an enormous variety of burst morphologies and a wide spread in burst durations. The spectra of gamma-ray bursts are characterized by rapid variations and peak power which is almost entirely in the gamma-ray energy range. Delayed gamma-ray burst photons extending to GeV energies have been detected for the first time. A time dilation effect has also been reported to be observed in gamma-ray, bursts. The observation of a gamma-ray burst counterpart in another wavelength region has yet to be made.

  13. Gamma-ray Astronomy and GLAST

    NASA Technical Reports Server (NTRS)

    McEnery, Julie

    2007-01-01

    The high energy gamma-ray (30 MeV to 100 GeV) sky has been relatively poorly studied. Most of our current knowledge comes from observations made by the Energetic Gamma Ray Experiment Telescope (EGRET) detector on the Compton Gamma Ray Observatory (CGRO), which revealed that the GeV gamma-ray sky is rich and vibrant. Studies of astrophysical objects at GeV energies are interesting for several reasons: The high energy gamma-rays are often produced by a different physical process than the better studied X-ray and optical emission, thus providing a unique information for understanding these sources. Production of such high-energy photons requires that charged particles are accelerated to equally high energies, or much greater. Thus gamma-ray astronomy is the study of extreme environments, with natural and fundamental connections to cosmic-ray and neutrino astrophysics. The launch of GLAST in 2008 will herald a watershed in our understanding of the high energy gamma-ray sky, providing dramatic improvements in sensitivity, angular resolution and energy range. GLAST will open a new avenue to study our Universe as well as to answer scientific questions EGRET observations have raised. In this talk, I will describe the GLAST instruments and capabilities and highlight some of the science we expect to address.

  14. Gamma-ray Astronomy and GLAST

    NASA Technical Reports Server (NTRS)

    McEnery, Julie

    2007-01-01

    The high energy gamma-ray (30 MeV to 100 GeV) sky has been relatively poorly studied. Most of our current knowledge comes from observations made by the Energetic Gamma Ray Experiment Telescope (EGRET) detector on the Compton Gamma Ray Observatory (CGRO), which revealed that the GeV gamma-ray sky is rich and vibrant. Studies of astrophysical objects at GeV energies are interesting for several reasons: The high energy gamma-rays are often produced by a different physical process than the better studied X-ray and optical emission, thus providing a unique information for understanding these sources. Production of such high-energy photons requires that charged particles are accelerated to equally high energies, or much greater. Thus gamma-ray astronomy is the study of extreme environments, with natural and fundamental connections to cosmic-ray and neutrino astrophysics. The launch of GLAST in 2008 will herald a watershed in our understanding of the high energy gamma-ray sky, providing dramatic improvements in sensitivity, angular resolution and energy range. GLAST will open a new avenue to study our Universe as well as to answer scientific questions EGRET observations have raised. In this talk, I will describe the GLAST instruments and capabilities and highlight some of the science we expect to address.

  15. NEAR Gamma Ray Spectrometer Characterization and Repair

    NASA Technical Reports Server (NTRS)

    Groves, Joel Lee; Vajda, Stefan

    1998-01-01

    This report covers the work completed in the third year of the contract. The principle activities during this period were (1) the characterization of the NEAR 2 Gamma Ray Spectrometer using a neutron generator to generate complex gamma ray spectra and a large Ge Detecter to identify all the major peaks in the spectra; (2) the evaluation and repair of the Engineering Model Unit of the Gamma Ray Spectrometer for the NEAR mission; (3) the investigation of polycapillary x-ray optics for x-ray detection; and (4) technology transfer from NASA to forensic science.

  16. Combination neutron-gamma ray detector

    DOEpatents

    Stuart, Travis P.; Tipton, Wilbur J.

    1976-10-26

    A radiation detection system capable of detecting neutron and gamma events and distinguishing therebetween. The system includes a detector for a photomultiplier which utilizes a combination of two phosphor materials, the first of which is in the form of small glass beads which scintillate primarily in response to neutrons and the second of which is a plastic matrix which scintillates in response to gammas. A combination of pulse shape and pulse height discrimination techniques is utilized to provide an essentially complete separation of the neutron and gamma events.

  17. Cosmic gamma-ray lines - Theory

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.; Ramaty, R.

    1980-01-01

    The various processes that lead to gamma-ray line emission and the possible astrophysical sources of such emission are reviewed. The processes of nuclear excitation, radiative capture, positron annihilation, and cyclotron radiation, which may produce gamma-ray line emission from such diverse sources as the interstellar medium, novas, supernovas, pulsars, accreting compact objects, the galactic nucleus and the nuclei of active galaxies are considered. The significance of the relative intensities, widths, and frequency shifts of the lines are also discussed. Particular emphasis is placed on understanding those gamma-ray lines that have already been observed from astrophysical sources.

  18. Detecting axionlike particles with gamma ray telescopes.

    PubMed

    Hooper, Dan; Serpico, Pasquale D

    2007-12-07

    We propose that axionlike particles (ALPs) with a two-photon vertex, consistent with all astrophysical and laboratory bounds, may lead to a detectable signature in the spectra of high-energy gamma-ray sources. This occurs as a result of gamma rays being converted into ALPs in the magnetic fields of efficient astrophysical accelerators according to the "Hillas criterion", such as jets of active galactic nuclei or hot spots of radio galaxies. The discovery of such an effect is possible by GLAST in the 1-100 GeV range and by ground-based gamma-ray telescopes in the TeV range.

  19. Isothermal deformation of gamma titanium aluminide

    SciTech Connect

    Srinivasan, R.; Singh, J.P.; Tuval, E.; Weiss, I.

    1996-04-15

    Gamma titanium aluminide has received considerable attention in recent years from the automotive industry as a potential material for making rotating and reciprocating components to produce a quieter and more efficient engine. The objectives of this study were to identify processing routes for the manufacture of automobile valves from gamma titanium aluminide. The issues considered were microstructure and composition of the material, and processing parameters such as deformation rates, temperatures, and total deformation. This paper examines isothermal deformation of gamma titanium aluminide in order to develop a processing window for this type of material.

  20. Fermi Gamma-Ray Space Telescope

    NASA Technical Reports Server (NTRS)

    McEnery, Julie E.; Michelson, Peter F.; Paclesas, William S.; Ritz, Steven

    2012-01-01

    The Fermi Gamma-ray Space Telescope, launched in June 2008, is an observatory designed to survey the high-energy gamma-ray sky. The primary instrument, the Large Area Telescope (LAT), provides observations from 20 MeV to greater than 300 GeV. A second instrument, the Gamma-ray Burst Monitor (GBM), provides observations of transients from less than 10 keV to 40 MeV. We describe the design and performance of the instruments and their subsystems, the spacecraft and the ground system.

  1. Collagen I confers gamma radiation resistance.

    PubMed

    Azorin, E; González-Martínez, P R; Azorin, J

    2012-12-01

    The effect of collagen on the response of somatomammotroph tumor cells (GH3) to gamma, radiation therapy was studied in vitro. After incubating confluent GH3 cell monolayers in a serum-free, maintaining medium, either with or without collagen, the monolayers were irradiated with 137Cs, gamma radiation. Collagen reduces cell mortality via ERK1/2 activation, abolishing gamma radiation, cell death, and promotes cell invasion when acting in synergy with collagen and in association with the, MAPK/ERK1/2 signaling pathway activation. The presence of collagen in somatomammotroph tumors, confers resistance to radiation.

  2. Modeling gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Maxham, Amanda

    Discovered serendipitously in the late 1960s, gamma-ray bursts (GRBs) are huge explosions of energy that happen at cosmological distances. They provide a grand physical playground to those who study them, from relativistic effects such as beaming, jets, shocks and blastwaves to radiation mechanisms such as synchrotron radiation to galatic and stellar populations and history. Through the Swift and Fermi space telescopes dedicated to observing GRBs over a wide range of energies (from keV to GeV), combined with accurate pinpointing that allows ground based follow-up observations in the optical, infrared and radio, a rich tapestry of GRB observations has emerged. The general picture is of a mysterious central engine (CE) probably composed of a black hole or neutron star that ejects relativistic shells of matter into intense magnetic fields. These shells collide and combine, releasing energy in "internal shocks" accounting for the prompt emission and flaring we see and the "external shock" or plowing of the first blastwave into the ambient surrounding medium has well-explained the afterglow radiation. We have developed a shell model code to address the question of how X-ray flares are produced within the framework of the internal shock model. The shell model creates randomized GRB explosions from a central engine with multiple shells and follows those shells as they collide, merge and spread, producing prompt emission and X-ray flares. We have also included a blastwave model, which can constrain X-ray flares and explain the origin of high energy (GeV) emission seen by the Fermi telescope. Evidence suggests that gamma-ray prompt emission and X-ray flares share a common origin and that at least some flares can only be explained by long-lasting central engine activity. We pay special attention to the time history of central engine activity, internal shocks, and observed flares. We calculate the gamma-ray (Swift/BAT band) and X-ray (Swift/XRT band) lightcurves for arbitrary

  3. Gamma-Gamma Angular Correlation Measurements With GRIFFIN

    NASA Astrophysics Data System (ADS)

    Maclean, Andrew; Griffin Collaboration

    2016-09-01

    The goal of this work was to explore the sensitivity of the Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei (GRIFFIN) 16 clover-detector γ-ray spectrometer at TRIUMF-ISAC to such γ - γ angular correlations. The methodology was established using both experimental measurements and Geant4 simulations that were used to create angular correlation templates for the GRIFFIN geometry. Direct comparisons were made between experimental data sets and the simulated angular correlation templates. A first in-beam test of the γ - γ angular correlation measurements with GRIFFIN was performed with a radioactive beam of 66Ga. Mixing ratios of δ = - 2 . 1(2) and δ = - 0 . 08(3) were measured for the 2+ ->2+ ->0+ 833-1039 keV and 1+ ->2+ ->0+ 2752-1039 keV cascades in the daughter nucleus 66Zn. These results are in good agreement with pervious literature values and the mixing ratio for the 833-1039 keV cascade has a higher precision. Also, the sensitivity to the 1333-1039 keV cascade, with its pronounced 0+ ->2+ ->0+ angular correlation, was measured.A test measurement of the superallowed Fermi β emitter 62Ga will also be discussed. Canada Foundation of Innovation, Natural Sciences and Engineering Research Council of Canada, National Research Council of Canada and Canadian Research Chairs Program.

  4. A Search for the Rare Decay $B\\rightarrow\\gamma\\gamma$

    SciTech Connect

    del Amo Sanchez, P.; Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, D.N.; Hooberman, B.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; Osipenkov, I.L.; Tanabe, T.; /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /Indian Inst. Tech., Guwahati /Harvard U. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa State U. /Iowa State U. /Johns Hopkins U. /Orsay, LAL /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /INFN, Naples /Naples U. /NIKHEF, Amsterdam /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /Rostock U. /Rutherford /DAPNIA, Saclay /SLAC /South Carolina U. /Southern Methodist U. /Stanford U., Phys. Dept. /SUNY, Albany /Tel Aviv U. /Tennessee U. /Texas Nuclear Corp., Austin /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U. /Victoria U. /Warwick U. /Wisconsin U., Madison

    2011-06-02

    We report the result of a search for the rare decay B{sup 0} {yields} {gamma}{gamma} in 426 fb{sup -1} of data, corresponding to 226 million B{sup 0}{bar B}{sup 0} pairs, collected on the {Upsilon}(4S) resonance at the PEP-II asymmetric-energy e{sup +}e{sup -} collider using the BABAR detector. We use a maximum likelihood fit to extract the signal yield and observe 21{sub -12}{sup +13} signal events with a statistical signficance of 1.9 {sigma}. This corresponds to a branching fraction {Beta}(B{sup 0} {yields} {gamma}{gamma}) = (1.7 {+-} 1.1(stat.) {+-} 0.2(syst.)) x 10{sup -7}. Based on this result, we set a 90% confidence level upper limit of {Beta}(B{sup 0} {yields} {gamma}{gamma}) < 3.2 x 10{sup -7}.

  5. The gamma 1 and gamma 3 bands of (16)O3: Line positions and intensities

    NASA Technical Reports Server (NTRS)

    Flaud, J.-M.; Camy-Peyret, C.; Devi, V. Malathy; Rinsland, C. P.; Smith, M. A. H.

    1988-01-01

    Using 0.005/cm-resolution Fourier transform spectra of samples of ozone, the gamma 1 and gamma 3 bands of (16)O3 have been reanalyzed to obtain accurate line positions and an extended set of upper state rotational levels (J up to 69, K sub a up to 20). Combined with the available microwave data, these upper state rotational levels were satisfactorily fitted using a Hamiltonian which takes explicitly into account the strong Coriolis interaction affecting the rotational levels of these two interacting states. In addition, 350 relative line intensities were measured from which the rotational expansions of the transition moment operators for the gamma 1 and gamma 3 states have been deduced. Finally, a complete listing of line positions, intensities, and lower state energies of the gamma 1 and gamma 3 bands of (16)O3 has been generated.

  6. Exclusive production of pion pairs in {gamma}*{gamma} collisions at Large Q{sup 2}

    SciTech Connect

    Diehl, M.

    2000-03-15

    The authors perform a QCD analysis of the exclusive production of two mesons in {gamma}*{gamma} collisions in the kinematical domain of large photon virtuality Q and small hadronic invariant mass W. This reaction is dominated by a scale invariant mechanism which factorizes into a perturbative subprocess, {gamma}*{gamma} {r{underscore}arrow} q{anti q} or {gamma}*{gamma} {r{underscore}arrow} gg, and a generalized two-meson distribution amplitude. The authors develop in detail the phenomenology of this process at e{sup +}e{sup {minus}} colliders. Using a simple model for the two-pion distribution amplitude, based on its general properties, the authors estimate the cross section for the kinematics accessible at BABAR, BELLE, CLEO and LEP.

  7. High-energy gamma rays from the intense 1993 January 31 gamma-ray burst

    NASA Technical Reports Server (NTRS)

    Sommer, M.; Bertsch, D. L.; Dingus, B. L.; Fichtel, C. E.; Fishman, G. J.; Harding, A. K.; Hartman, R. C.; Hunter, S. D.; Hurley, K.; Kanbach, G.

    1994-01-01

    The intense gamma-ray burst of 1993 January 31 was detected by the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Observatory. Sixteen gamma rays above 30 MeV were imaged in the telescope when only 0.04 gamma rays were expected by chance. Two of these gamma rays have energies of approximately 1 GeV, and the five bin spectrum of the 16 events is fitted by a power law of photon spectral index -2.0 +/- 0.4. The high-energy emission extends for at least 25 s. The most probable direction for this burst is determined from the directions of the 16 gamma rays observed by Egret and also by requiring the position to lie on annulus derived by the Interplanetary Network.

  8. GammaLib: A New Framework for the Analysis of Astronomical Gamma-Ray Data

    NASA Astrophysics Data System (ADS)

    Knödlseder, J.

    2012-09-01

    With the advent of a new generation of telescopes (INTEGRAL, Fermi, H.E.S.S., MAGIC, VERITAS, MILAGRO) and the prospects of planned observatories such as CTA or HAWC, gamma-ray astronomy is becoming an integral part of modern astrophysical research. Analysing gamma-ray data is still a major challenge, and today relies on a large diversity of tools and software frameworks that were specifically developed for each instrument. With the goal of facilitating and unifying the analysis of gamma-ray data, we are currently developing an innovative data analysis toolbox, called the GammaLib, that enables gamma-ray data analysis in an instrument independent way. We will present the basic ideas that are behind the GammaLib, and describe its architecture and usage.

  9. Higgs mediated flavor violating top quark decays t{yields}u{sub i}H, u{sub i{gamma}}, u{sub i{gamma}{gamma}}, and the process {gamma}{gamma}{yields}tc in effective theories

    SciTech Connect

    Aranda, J. I.; Ramirez-Zavaleta, F.; Tututi, E. S.; Toscano, J. J.

    2010-04-01

    The rare top quark couplings tu{sub i{gamma}} and tu{sub i{gamma}{gamma}} (u{sub i}=u, c) induced at the one-loop level by a flavor violating tu{sub i}H vertex are studied within the context of an effective Yukawa sector that incorporates SU{sub L}(2)xU{sub Y}(1)-invariant operators of up to dimension six. Data on the recently observed D{sup 0}-D{sup 0} mixing are employed to constrain the tu{sub i}H vertex, which is then used to predict the t{yields}u{sub i}H, t{yields}u{sub i{gamma}}, and t{yields}u{sub i{gamma}{gamma}} decays, as well as the {gamma}{gamma}{yields}tu{sub i}+tu{sub i} reaction in the context of the ILC. It is found that the t{yields}cH and t{yields}c{gamma}{gamma} decays can reach sizable branching ratios as high as 5x10{sup -3} and 10{sup -4}, respectively. As for the t{yields}c{gamma} decay, it can have a branching ratio of 5x10{sup -8} that is about 6 orders of magnitude larger than the standard model prediction, which, however, is still very small to be detected. As for tc production, it is found that, due to the presence of a resonant effect in the convoluted cross section {sigma}(e{sup +}e{sup -{yields}{gamma}{gamma}{yields}}tc+tc), about (0.5-2.7)x10{sup 3} tc events may be produced at the ILC for a value of the Higgs mass near to the top mass.

  10. Method of incident low-energy gamma-ray direction reconstruction in the GAMMA-400 gamma-ray space telescope

    NASA Astrophysics Data System (ADS)

    Kheymits, M. D.; Leonov, A. A.; Zverev, V. G.; Galper, A. M.; Arkhangelskaya, I. V.; Arkhangelskiy, A. I.; Suchkov, S. I.; Topchiev, N. P.; Yurkin, Yu T.; Bakaldin, A. V.; Dalkarov, O. D.

    2016-02-01

    The GAMMA-400 gamma-ray space-based telescope has as its main goals to measure cosmic γ-ray fluxes and the electron-positron cosmic-ray component produced, theoretically, in dark-matter-particles decay or annihilation processes, to search for discrete γ-ray sources and study them in detail, to examine the energy spectra of diffuse γ-rays — both galactic and extragalactic — and to study gamma-ray bursts (GRBs) and γ-rays from the active Sun. Scientific goals of GAMMA-400 telescope require fine angular resolution. The telescope is of a pair-production type. In the converter-tracker, the incident gamma-ray photon converts into electron-positron pair in the tungsten layer and then the tracks are detected by silicon- strip position-sensitive detectors. Multiple scattering processes become a significant obstacle in the incident-gamma direction reconstruction for energies below several gigaelectronvolts. The method of utilising this process to improve the resolution is proposed in the presented work.

  11. Tests of quantum chromodynamics in exclusive e sup + e sup minus and. gamma. gamma. processes

    SciTech Connect

    Brodsky, S.J.

    1989-09-01

    This paper discusses the following topics: Factorization theorem for exclusive processes; Electromagnetic form factors of baryons; Suppression of final state interactions; The {gamma}{pi}{sub 0} Transition form factor; Exclusive charmonium decays; The {pi}-{rho} puzzle; Time-like compton processes; Multi-hadron production; Heavy Quark exclusive states and form factor zeros in QCD; Exclusive {gamma}{gamma} reactions; Higher twist effects; and Tauonium and threshold {tau}{sup +}{tau}{sup {minus}} production. 41 refs., 15 figs. (LSP)

  12. Radon concentration monitoring using xenon gamma-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Novikov, A.; Ulin, S.; Dmitrenko, V.; Chernysheva, I.; Grachev, V.; Vlasik, K.; Uteshev, Z.; Shustov, A.; Petrenko, D.; Bychkova, O.

    2017-01-01

    A method for 222Rn concentration monitoring by means of intensity measurement of its daughter nuclei (214Pb and 214Bi) gamma-ray emission using xenon gamma-ray spectrometer is presented. Testing and calibration results for a gamma-spectrometric complex based on xenon gamma-ray detector are described.

  13. Hardness Evolution of Gamma-Irradiated Polyoxymethylene

    NASA Astrophysics Data System (ADS)

    Hung, Chuan-Hao; Harmon, Julie P.; Lee, Sanboh

    2016-12-01

    This study focuses on analyzing hardness evolution in gamma-irradiated polyoxymethylene (POM) exposed to elevated temperatures after irradiation. Hardness increases with increasing annealing temperature and time, but decreases with increasing gamma ray dose. Hardness changes are attributed to defects generated in the microstructure and molecular structure. Gamma irradiation causes a decrease in the glass transition temperature, melting point, and extent of crystallinity. The kinetics of defects resulting in hardness changes follow a first-order structure relaxation. The rate constant adheres to an Arrhenius equation, and the corresponding activation energy decreases with increasing dose due to chain scission during gamma irradiation. The structure relaxation of POM has a lower energy barrier in crystalline regions than in amorphous ones. The hardness evolution in POM is an endothermic process due to the semi-crystalline nature of this polymer.

  14. Gamma-Ray Pulsar Studies With GLAST

    SciTech Connect

    Thompson, D.J.; /NASA, Goddard

    2011-11-23

    Some pulsars have their maximum observable energy output in the gamma-ray band, offering the possibility of using these high-energy photons as probes of the particle acceleration and interaction processes in pulsar magnetospheres. After an extended hiatus between satellite missions, the recently-launched AGILE mission and the upcoming Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) will allow gamma-ray tests of the theoretical models developed based on past discoveries. With its greatly improved sensitivity, better angular resolution, and larger energy reach than older instruments, GLAST LAT should detect dozens to hundreds of new gamma-ray pulsars and measure luminosities, light curves, and phase-resolved spectra with unprecedented resolution. It will also have the potential to find radio-quiet pulsars like Geminga, using blind search techniques. Cooperation with radio and X-ray pulsar astronomers is an important aspect of the LAT team's planning for pulsar studies.

  15. Solar flare gamma-ray line shapes

    NASA Technical Reports Server (NTRS)

    Werntz, C.; Kim, Y. E.; Lang, Frederick L.

    1990-01-01

    A computer code has been developed which is used to calculate ab initio the laboratory shapes and energy shifts of gamma-ray lines from (C-12)(p, gamma/4.438/)p-prime(C-12) and (O-16)(p, gamma/6.129/)p-prime(O-16) reactions and to calculate the expected shapes of these lines from solar flares. The sensitivity of observable solar flare gamma-ray line shapes to the directionality of the incident particles is investigated for several projectile angular distributions. Shapes of the carbon and oxygen lines are calculated assuming realistic proton energy spectra for particles in circular orbits at the mirror points of magnetic loops, for particle beams directed downward into the photosphere, and for isotropic particle distributions. Line shapes for flare sites near the center of the sun and on the limb are shown for both thin-target and thick-target interaction models.

  16. Gamma rays from giant molecular clouds

    NASA Technical Reports Server (NTRS)

    Hunter, Stanley D.; Kanbach, Gottfried

    1990-01-01

    Giant Molecular Clouds (GMCs) are massive, bounded, cool, dense regions containing mostly H2, but also H I, CO, and other molecules. These clouds occupy less than 1 percent of the galactic volume, but are a substantial part of the interstellar mass. They are irradiated by the high energy cosmic rays which are possibly modulated by the matter and magnetic fields within the clouds. The product of cosmic-ray flux and matter density is traced by the emission of high energy gamma-rays. A spherical cloud model is considered and the gamma ray flux from several GMCs within 1 kpc of the sun which should be detectable by the EGRET (Energetic Gamma-Ray Experimental Telescope) instrument on GRO (Gamma Ray Observatory).

  17. Gamma-ray spectroscopy - Requirements and prospects

    NASA Technical Reports Server (NTRS)

    Matteson, James L.

    1991-01-01

    The only previous space instrument which had sufficient spectral resolution and directionality for the resolution of astrophysical sources was the Gamma-Ray Spectrometer carried by HEAO-3. A broad variety of astrophysical investigations entail gamma-ray spectroscopy of E/Delta-E resolving power of the order of 500 at 1 MeV; it is presently argued that a sensitivity to narrow gamma-ray lines of a few millionths ph/sq cm, from about 10 keV to about 10 MeV, should typify the gamma-ray spectrometers of prospective missions. This performance is achievable with technology currently under development, and could be applied to the NASA's planned Nuclear Astrophysics Explorer.

  18. Airborne Gamma-Spectrometry in Switzerland

    NASA Astrophysics Data System (ADS)

    Butterweck, Gernot; Bucher, Benno; Rybach, Ladislaus

    2008-08-01

    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 137Cs 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.

  19. Gamma beam system at ELI-NP

    SciTech Connect

    Ur, Calin Alexandru

    2015-02-24

    The Gamma Beam System of ELI-NP will produce brilliant, quasi-monochromatic gamma-ray beams via Inverse Compton Scattering of short laser pulses on relativistic electron beam pulses. The scattered radiation is Doppler upshifted by more than 1,000,000 times and is forward focused in a narrow, polarized, tunable, laser-like beam. The gamma-ray beam at ELI-NP will be characterized by large spectral density of about 10{sup 4} photons/s/eV, narrow bandwidth (< 0.5%) and tunable energy from 200 keV up to about 20 MeV. The Gamma Beam System is a state-of-the-art equipment employing techniques and technologies at the limits of the present-day's knowledge.

  20. Gamma Rays at Very High Energies

    NASA Astrophysics Data System (ADS)

    Aharonian, Felix

    This chapter presents the elaborated lecture notes on Gamma Rays at Very High Energies given by Felix Aharonian at the 40th Saas-Fee Advanced Course on "Astrophysics at Very High Energies". Any coherent description and interpretation of phenomena related to gammarays requires deep knowledge of many disciplines of physics like nuclear and particle physics, quantum and classical electrodynamics, special and general relativity, plasma physics, magnetohydrodynamics, etc. After giving an introduction to gamma-ray astronomy the author discusses the astrophysical potential of ground-based detectors, radiation mechanisms, supernova remnants and origin of the galactic cosmic rays, TeV emission of young supernova remnants, gamma-emission from the Galactic center, pulsars, pulsar winds, pulsar wind nebulae, and gamma-ray loud binaries.

  1. A localized excess of diffuse gamma radiation

    NASA Technical Reports Server (NTRS)

    Chen, A.; Dwyer, J.; Kaaret, P.

    1995-01-01

    Using archival Energetic Gamma Ray Experiment Telescope (EGRET) gamma-ray data and atomic hydrogen (H I) column densities derived from 21 cm radio observations, we have found a large irregular region in the northern Galactic hemisphere extending from (l approximately 90 deg, b approximately 52 deg) to (l approximately 45 deg, b approximately 77 deg) with a significant enhancement in the gamma-ray emissivity compared to the surrounding sky. The region contains no previously identified gamma-ray point sources. The emission may arise from a localized enhancement in cosmic-ray density or from the presence of matter other than H I. If the emission is due to unseen matter, a column density enhancement equivalent to approximately 2 x 10(exp 20) H-atoms/sq cm is required.

  2. Compact Electronic Gamma Source For Radiotherapy

    SciTech Connect

    Chen, A. X.; Antolak, A. J.; Raber, T. N.; Morse, D. H.; Leung, K.-N.

    2011-06-01

    A compact mono-energetic gamma source is being developed to replace the radiological sources used in radiotherapy and other medical instruments. The electronic gamma source utilizes low-energy nuclear reactions to generate gammas in the 0.5 to 1.0 MeV energy range. Independent control of the ion current and energy is achieved by decoupling the RF-driven ion source and pyroelectric crystal-based acceleration systems The ions are accelerated to voltages above 100 keV and bombard a reaction target to produce gammas. Thermal management of the pyroelectric crystal-based accelerator is achieved by convective dielectric fluid flow around the crystal. This approach provides better temperature uniformity in the crystal and higher dielectric strength for suppressing voltage breakdown and enabling faster thermal cycling rates.

  3. 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.

  4. HotSpotter? Neutron/Gamma Detector

    SciTech Connect

    Bell, Z.W.

    2003-04-01

    The HotSpotter{trademark} Neutron/Gamma Detector combines in a single detecting module high sensitivity to gamma rays up to 3 MeV and sensitivity to neutrons. Using a 15 mm cubic CdWO{sub 4} (cadmium tungstate) crystal mounted on a 25 mm photomultiplier, the instrument realizes a factor of 5 increased photopeak efficiency over NaI(Tl) at 1 MeV, and a factor of 2 improvement over CsI(Tl). The addition of a 0.5 mm layer of {sup 10}B- impregnated epoxy covering the crystal provides neutron sensitivity without sacrificing gamma ray spectroscopic characteristics. Neutrons are detected by the presence of the 478 keV gamma from the {sup 10}B(n,{alpha}){sup 7}Li* reaction. In this paper, we describe the electronics and software of the instrument, and some of its characteristics.

  5. Gamma-ray observatory INTEGRAL reloaded

    NASA Astrophysics Data System (ADS)

    van den Heuvel, Edward P. J.

    2017-04-01

    The scientific aims of the European Space Agency's International Gamma-Ray Astrophysics Laboratory are considerably extended because of its unique capability to identify electromagnetic counterparts to sources of gravitational waves and ultra-high-energy neutrinos.

  6. Overview Animation of Gamma-ray Burst

    NASA Image and Video Library

    Gamma-ray bursts are the most luminous explosions in the cosmos. Astronomers think most occur when the core of a massive star runs out of nuclear fuel, collapses under its own weight, and forms a b...

  7. High resolution gamma spectroscopy well logging system

    SciTech Connect

    Giles, J.R.; Dooley, K.J.

    1997-05-01

    A Gamma Spectroscopy Logging System (GSLS) has been developed to study sub-surface radionuclide contamination. The absolute counting efficiencies of the GSLS detectors were determined using cylindrical reference sources. More complex borehole geometries were modeled using commercially available shielding software and correction factors were developed based on relative gamma-ray fluence rates. Examination of varying porosity and moisture content showed that as porosity increases, and as the formation saturation ratio decreases, relative gamma-ray fluence rates increase linearly for all energies. Correction factors for iron and water cylindrical shields were found to agree well with correction factors determined during previous studies allowing for the development of correction factors for type-304 stainless steel and low-carbon steel casings. Regression analyses of correction factor data produced equations for determining correction factors applicable to spectral gamma-ray well logs acquired under non-standard borehole conditions.

  8. Solar flare gamma-ray line shapes

    NASA Technical Reports Server (NTRS)

    Werntz, C.; Kim, Y. E.; Lang, Frederick L.

    1990-01-01

    A computer code has been developed which is used to calculate ab initio the laboratory shapes and energy shifts of gamma-ray lines from (C-12)(p, gamma/4.438/)p-prime(C-12) and (O-16)(p, gamma/6.129/)p-prime(O-16) reactions and to calculate the expected shapes of these lines from solar flares. The sensitivity of observable solar flare gamma-ray line shapes to the directionality of the incident particles is investigated for several projectile angular distributions. Shapes of the carbon and oxygen lines are calculated assuming realistic proton energy spectra for particles in circular orbits at the mirror points of magnetic loops, for particle beams directed downward into the photosphere, and for isotropic particle distributions. Line shapes for flare sites near the center of the sun and on the limb are shown for both thin-target and thick-target interaction models.

  9. Gamma-Ray "Raindrops" from Flaring Blazar

    NASA Image and Video Library

    2017-09-28

    This visualization shows gamma rays detected during 3C 279's big flare by the LAT instrument on NASA's Fermi satellite. Gamma rays are represented as expanding circles reminiscent of raindrops on water. The flare is an abrupt shower of "rain" that trails off toward the end of the movie. Both the maximum size of the circle and its color represent the energy of the gamma ray, with white lowest and magenta highest. In a second version of the visualization, a background map shows how the LAT detects 3C 279 and other sources by accumulating high-energy photons over time (brighter squares reflect higher numbers of gamma rays). The movie starts on June 14 and ends June 17. The area shown is a region of the sky five degrees on a side and centered on the position of 3C 279. Read more: go.nasa.gov/1TqximF Credits: NASA/DOE/Fermi LAT Collaboration

  10. POPULATION SYNTHESIS AND GAMMA RAY BURST PROGENITORS

    SciTech Connect

    C. L. FREYER

    2000-12-11

    Population synthesis studies of binaries are always limited by a myriad of uncertainties from the poorly understood effects of binary mass transfer and common envelope evolution to the many uncertainties that still remain in stellar evolution. But the importance of these uncertainties depends both upon the objects being studied and the questions asked about these objects. Here I review the most critical uncertainties in the population synthesis of gamma-ray burst progenitors. With a better understanding of these uncertainties, binary population synthesis can become a powerful tool in understanding, and constraining, gamma-ray burst models. In turn, as gamma-ray bursts become more important as cosmological probes, binary population synthesis of gamma-ray burst progenitors becomes an important tool in cosmology.

  11. Status of the GAMMA-400 project

    NASA Astrophysics Data System (ADS)

    Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Gusakov, Yu. V.; Farber, M. O.; Fradkin, M. I.; Kachanov, V. A.; Kaplin, V. A.; Kheymits, M. D.; Leonov, A. A.; Longo, F.; Maestro, P.; Marrocchesi, P.; Mazets, E. P.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I.; Naumov, P. Yu.; Papini, P.; Picozza, P.; Rodin, V. G.; Runtso, M. F.; Sparvoli, R.; Spillantini, P.; Suchkov, S. I.; Tavani, M.; Topchiev, N. P.; Vacchi, A.; Vannuccini, E.; Yurkin, Yu. T.; Zampa, N.; Zverev, V. G.

    2013-01-01

    The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100 MeV-3 TeV is presented. The angular resolution of the instrument, 1-2° at Eγ ˜ 100 MeV and ˜0.01° at Eγ > 100 GeV, its energy resolution ˜1% at Eγ > 100 GeV, and the proton rejection factor ˜106 are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.

  12. SEARCH FOR THE EXCLUSIVE RADIATIVE DECAYS B ---> RHO GAMMA AND B0 ---> OMEGA GAMMA

    SciTech Connect

    Convery, Mark R

    2002-07-26

    A search for the exclusive radiative decays B {yields} {rho}(770){gamma} and B{sup 0} {yields} {omega}(782){gamma} is performed on a sample of 84 million B{bar B} events collected by the BaBar detector at the PEP-II asymmetric e{sup +}e{sup -} collider. No significant signal is seen in any of the channels. They set preliminary upper limits of {Beta}[B{sup 0} {yields} {rho}{sup 0}{gamma}] < 1.4 x 10{sup -6}, {Beta}[B{sup +} {yields} {rho}{sup +}{gamma}] < 2.3 x 10{sup -6} and {Beta}[B{sup 0} {yields} {omega}{gamma}] < 1.2 x 10{sup -6} at 90% Confidence Level. Combining these into a single limit on the generic process B {yields} {rho}{gamma}, they find the preliminary limit {Beta}[B {yields} {rho}{gamma}] < 1.9 x 10{sup -6} corresponding, to a limit of {Beta}[B {yields} {rho}{gamma}]/{Beta}[B {yields} K*{gamma}] < 0.047 at 90% Confidence Level.

  13. Phase separation in aqueous solutions of lens gamma-crystallins: special role of gamma s.

    PubMed Central

    Liu, C; Asherie, N; Lomakin, A; Pande, J; Ogun, O; Benedek, G B

    1996-01-01

    We have studied liquid-liquid phase separation in aqueous ternary solutions of calf lens gamma-crystallin proteins. Specifically, we have examined two ternary systems containing gamma s--namely, gamma IVa with gamma s in water and gamma II with gamma s in water. For each system, the phase-separation temperatures (Tph (phi)) alpha as a function of the overall protein volume fraction phi at various fixed compositions alpha (the "cloud-point curves") were measured. For the gamma IVa, gamma s, and water ternary solution, a binodal curve composed of pairs of coexisting points, (phi I, alpha 1) and (phi II, alpha II), at a fixed temperature (20 degrees C) was also determined. We observe that on the cloud-point curve the critical point is at a higher volume fraction than the maximum phase-separation temperature point. We also find that typically the difference in composition between the coexisting phases is at least as significant as the difference in volume fraction. We show that the asymmetric shape of the cloud-point curve is a consequence of this significant composition difference. Our observation that the phase-separation temperature of the mixtures in the high volume fraction region is strongly suppressed suggests that gamma s-crystallin may play an important role in maintaining the transparency of the lens. PMID:8552642

  14. Samarium(II) promoted stereoselective synthesis of antiproliferative cis-beta-alkoxy-gamma-alkyl-gamma-lactones.

    PubMed

    Donadel, Osvaldo J; Martín, Tomás; Martín, Víctor S; Padrón, José M

    2007-01-01

    Samarium(II) iodide promotes the stereoselective synthesis of cis-beta-alkoxy-gamma-alkyl-gamma-lactones under mild conditions starting from linear precursors. The in vitro antiproliferative activities were examined in the human solid tumor cell lines from diverse origin A2780, SW1573, and WiDr. From the growth inhibition data a structure-activity relationship was obtained. Overall the results point to the relevant role of cis-beta-alkoxy-gamma-alkyl-gamma-lactones as novel scaffolds for the development of new anticancer drugs.

  15. Electrophoretic separation of A gamma and G gamma human globin chains in Nonidet P-40.

    PubMed

    Guerrasio, A; Saglio, G; Mazza, U; Pich, P; Camaschella, C; Ricco, G; Gianazza, E; Righetti, P G

    1979-11-15

    Electrophoresis in cellulose acetate in the presence of 3% Nonidet P-40 can resolve two neutral genetic variants, A gamma and G gamma human fetal globin chains. The ratio of these two chains, determined by densitometry of the electrophoretic strips, is in excellent agreement with the Gly-Ala ratio obtained by chemical analysis of the cyanogen bromide fragment gamma CB3. It is suggested that the detergent binds preferentially to the hydrophobic amino acid segment 133-141 in the A gamma chain, thus masking either a Lys or an Arg residue at the two extremes.

  16. A method to describe inelastic gamma field distribution in neutron gamma density logging.

    PubMed

    Zhang, Feng; Zhang, Quanying; Liu, Juntao; Wang, Xinguang; Wu, He; Jia, Wenbao; Ti, Yongzhou; Qiu, Fei; Zhang, Xiaoyang

    2017-08-21

    Pulsed neutron gamma density logging (NGD) is of great significance for radioprotection and density measurement in LWD, however, the current methods have difficulty in quantitative calculation and single factor analysis for the inelastic gamma field distribution. In order to clarify the NGD mechanism, a new method is developed to describe the inelastic gamma field distribution. Based on the fast-neutron scattering and gamma attenuation, the inelastic gamma field distribution is characterized by the inelastic scattering cross section, fast-neutron scattering free path, formation density and other parameters. And the contribution of formation parameters on the field distribution is quantitatively analyzed. The results shows the contribution of density attenuation is opposite to that of inelastic scattering cross section and fast-neutron scattering free path. And as the detector-spacing increases, the density attenuation gradually plays a dominant role in the gamma field distribution, which means large detector-spacing is more favorable for the density measurement. Besides, the relationship of density sensitivity and detector spacing was studied according to this gamma field distribution, therefore, the spacing of near and far gamma ray detector is determined. The research provides theoretical guidance for the tool parameter design and density determination of pulsed neutron gamma density logging technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Enzymatic synthesis of radioactive (-)-carnitine from. gamma. -butyrobetaine prepared by the methylation of. gamma. -aminobutyric acid

    SciTech Connect

    Daveluy, A.; Parvin, R.; Pande, S.V.

    1982-01-15

    Radioactive ..gamma..-butyrobetaine was prepared by quaternization of ..gamma..-aminobutyric acid with tritiated methyl iodide under conditions giving high yields with respect to both the above precursors. Part of the product was passed through a column of ion-retardation resin and gave radioactive ..gamma..-butyrobetaine of good purity. The remainder was converted to (-)-carnitine stoichiometrically by employing a 50-60% ammonium sulfate fraction of rat liver supernatant as the source of ..gamma..-butyrobetaine hydroxylase (EC 1,14,11,1) Successive column chromatographies on a cation exchanger and ion-retardation resins then gave radioactive (-)-carnitine of good purity in high yield.

  18. Laser Electron Gamma Source Facility biennial progress report, June 1992

    SciTech Connect

    Caracappa, A.; Kuczewski, A.; Kistner, O.C.; Lincoln, F. ); Hoblit, S. . Dept. of Physics); Whisnant, C.S. South Carolina Univ., Columbia, SC . Dept. of Physics)

    1992-01-01

    This report briefly discusses the Laser Electron Gamma Source facility and the following experiments conducted here: polarization in D(gamma, p)n and N-N tensor forces for energies less than 225 Mev; constraints on the nuclear tensor force from D(gamma, p)n for energies less than 315 Mev; the p(gamma, neutral pion) reaction and the E2 excitation of delta resonance; quasi-two- and three-body absorption in helium 3(gamma, N-N); and the delta-nucleon interaction in D(gamma,p-negative pion)p and D(gamma, p-n)neutral pions. (LSP).

  19. Laser Electron Gamma Source Facility biennial progress report, June 1992

    SciTech Connect

    Caracappa, A.; Kuczewski, A.; Kistner, O.C.; Lincoln, F.; Hoblit, S.; Whisnant, C.S. |

    1992-08-01

    This report briefly discusses the Laser Electron Gamma Source facility and the following experiments conducted here: polarization in D(gamma, p)n and N-N tensor forces for energies less than 225 Mev; constraints on the nuclear tensor force from D(gamma, p)n for energies less than 315 Mev; the p(gamma, neutral pion) reaction and the E2 excitation of delta resonance; quasi-two- and three-body absorption in helium 3(gamma, N-N); and the delta-nucleon interaction in D(gamma,p-negative pion)p and D(gamma, p-n)neutral pions. (LSP).

  20. Higgs mediated lepton flavor violating tau decays {tau}{yields}{mu}{gamma} and {tau}{yields}{mu}{gamma}{gamma} in effective theories

    SciTech Connect

    Aranda, J. I.; Tututi, E. S.; Toscano, J. J.

    2008-07-01

    The size of the branching ratios for the {tau}{yields}{mu}{gamma} and {tau}{yields}{mu}{gamma}{gamma} decays induced by a lepton flavor violating Higgs interaction H{tau}{mu} is studied in the framework of effective field theories. The best constraint on the H{tau}{mu} vertex, derived from the know measurement on the muon anomalous magnetic moment, is used to impose the upper bounds Br({tau}{yields}{mu}{gamma})<7.5x10{sup -10} and Br({tau}{yields}{mu}{gamma}{gamma})<2.3x10{sup -12}, which are more stringent than current experimental limits on this class of transitions.

  1. Gamma-ray burst cosmology

    NASA Astrophysics Data System (ADS)

    Wang, F. Y.; Dai, Z. G.; Liang, E. W.

    2015-08-01

    Gamma-ray bursts (GRBs) are the most luminous electromagnetic explosions in the Universe, which emit up to 8.8 × 1054 erg isotropic equivalent energy in the hard X-ray band. The high luminosity makes them detectable out to the largest distances yet explored in the Universe. GRBs, as bright beacons in the deep Universe, would be the ideal tool to probe the properties of high-redshift universe: including the cosmic expansion and dark energy, star formation rate, the reionization epoch and the metal enrichment history of the Universe. In this article, we review the luminosity correlations of GRBs, and implications for constraining the cosmological parameters and dark energy. Observations show that the progenitors of long GRBs are massive stars. So it is expected that long GRBs are tracers of star formation rate. We also review the high-redshift star formation rate derived from GRBs, and implications for the cosmic reionization history. The afterglows of GRBs generally have broken power-law spectra, so it is possible to extract intergalactic medium (IGM) absorption features. We also present the capability of high-redshift GRBs to probe the pre-galactic metal enrichment and the first stars.

  2. Gamma-Ray Burst Progenitors

    NASA Astrophysics Data System (ADS)

    Levan, Andrew; Crowther, Paul; de Grijs, Richard; Langer, Norbert; Xu, Dong; Yoon, Sung-Chul

    2016-12-01

    We review our current understanding of the progenitors of both long and short duration gamma-ray bursts (GRBs). Constraints can be derived from multiple directions, and we use three distinct strands; (i) direct observations of GRBs and their host galaxies, (ii) parameters derived from modelling, both via population synthesis and direct numerical simulation and (iii) our understanding of plausible analog progenitor systems observed in the local Universe. From these joint constraints, we describe the likely routes that can drive massive stars to the creation of long GRBs, and our best estimates of the scenarios that can create compact object binaries which will ultimately form short GRBs, as well as the associated rates of both long and short GRBs. We further discuss how different the progenitors may be in the case of black hole engine or millisecond-magnetar models for the production of GRBs, and how central engines may provide a unifying theme between many classes of extremely luminous transient, from luminous and super-luminous supernovae to long and short GRBs.

  3. Recombinant human gamma interferon inhibits simian malaria.

    PubMed Central

    Maheshwari, R K; Czarniecki, C W; Dutta, G P; Puri, S K; Dhawan, B N; Friedman, R M

    1986-01-01

    Prophylactic treatment with 0.1 mg of human gamma interferon per kg (body weight) per day completely suppressed experimental infection with Plasmodium cynomolgi B sporozoites in rhesus monkeys. Treatment with lower doses partially suppressed this infection. Prophylactic treatment with human gamma interferon, however, had no protective effect against trophozoite-induced infection, suggesting that the interferon effect was limited to the exoerythrocytic stage of parasitic development. PMID:3091507

  4. Gamma Imaging using Rotational Modulation Collimation

    DTIC Science & Technology

    2014-01-01

    Gamma imaging techniques 2 2.1 Compton imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.2 Pinhole or parallel-hole collimation...imaging techniques that are of relevance to national security applications. 2.1 Compton imaging Compton scattering is a specific interaction...Overlaying multiple trajectory cones over many gamma photon interactions reveals the source position, and this forms the basis for the technique of Compton

  5. Gamma heating measurements with proportional counters

    SciTech Connect

    Chiu, H.; Bennett, E.F.; Micklich, B.J.

    1990-05-01

    A new data acquisition technique (the Continuously-varied Bias- voltage Acquisition mode) has been developed and tested for the low-flux broad-energy regime characteristic of existing fusion blanket mock-ups. This method of analysis allows for the acquisition of data spanning several orders of magnitude in energy with a single proportional counter. Utilizing this method, the gamma energy deposition in a mixed neutron and gamma field was measured. 7 refs., 5 figs.

  6. Gamma radiation induced resistivity changes in Iron

    NASA Astrophysics Data System (ADS)

    Tundwal, Ambika; Kumar, V.; Datta, A.

    2017-03-01

    Monte Carlo Code JA-IPU is used for estimation of Frenkel pairs and their effect on change of resistivity of Iron on irradiation by gamma spectrum of Co60. The Code includes three cascade processes of incident gamma, produced electrons and recoiled atoms and simulation of the lattice structure of the target material. Change in experimentally measured resistivity of Iron is found to vary with number of Frenkel pairs as (x - 1) ln N d .

  7. Ballerina - pirouettes in search of gamma bursts

    NASA Astrophysics Data System (ADS)

    Brandt, S.; Lund, N.; Pedersen, H.; Hjorth, J.; BALLERINA Collaboration

    1999-09-01

    The cosmological origin of gamma ray bursts has now been established with reasonable certainty. Many more bursts will need to be studied to establish the typical distance scale, and to map out the large diversity in properties which have been indicated by the first handful of events. We are proposing Ballerina, a small satellite to provide accurate positions and new data on the gamma-ray bursts. We anticipate a detection rate an order of magnitude larger than obtained from Beppo-SAX.

  8. Observation of J/psi-->3gamma.

    PubMed

    Adams, G S; Anderson, M; Cummings, J P; Danko, I; Hu, D; Moziak, B; Napolitano, J; He, Q; Insler, J; Muramatsu, H; Park, C S; Thorndike, E H; Yang, F; Artuso, M; Blusk, S; Khalil, S; Li, J; Mountain, R; Nisar, S; Randrianarivony, K; Sultana, N; Skwarnicki, T; Stone, S; Wang, J C; Zhang, L M; Bonvicini, G; Cinabro, D; Dubrovin, M; Lincoln, A; Naik, P; Rademacker, J; Asner, D M; Edwards, K W; Reed, J; Briere, R A; Ferguson, T; Ma, J S Y; Tatishvili, G; Vogel, H; Watkins, M E; Rosner, J L; Alexander, J P; Cassel, D G; Duboscq, J E; Ehrlich, R; Fields, L; Galik, R S; Gibbons, L; Gray, R; Gray, S W; Hartill, D L; Heltsley, B K; Hertz, D; Hunt, J M; Kandaswamy, J; Kreinick, D L; Kuznetsov, V E; Ledoux, J; Mahlke-Krüger, H; Mohapatra, D; Onyisi, P U E; Patterson, J R; Peterson, D; Riley, D; Ryd, A; Sadoff, A J; Shi, X; Stroiney, S; Sun, W M; Wilksen, T; Athar, S B; Patel, R; Yelton, J; Rubin, P; Eisenstein, B I; Karliner, I; Mehrabyan, S; Lowrey, N; Selen, M; White, E J; Wiss, J; Mitchell, R E; Shepherd, M R; Besson, D; Pedlar, T K; Cronin-Hennessy, D; Gao, K Y; Hietala, J; Kubota, Y; Klein, T; Lang, B W; Poling, R; Scott, A W; Zweber, P; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A; Libby, J; Powell, A; Wilkinson, G; Ecklund, K M; Love, W; Savinov, V; Mendez, H; Ge, J Y; Miller, D H; Shipsey, I P J; Xin, B

    2008-09-05

    We report the first observation of the decay J/psi-->3gamma. The signal has a statistical significance of 6sigma and corresponds to a branching fraction of B(J/psi-->3gamma)=(1.2+/-0.3+/-0.2)x10;{-5}, in which the errors are statistical and systematic, respectively. The measurement uses psi(2S)-->pi;{+}pi;{-}J/psi events acquired with the CLEO-c detector operating at the CESR e;{+}e;{-} collider.

  9. Dark Matter Indirect Detection with Gamma Rays

    DOE PAGES

    Patrick Harding, J.

    2017-07-27

    Searches for weakly interacting massive particle (WIMP) dark matter with gamma-ray instruments are a way to get a unique observational handle on the particle nature of dark matter. I will discuss the details of how to perform these searches, both for annihilating and decaying WIMPs. I will discuss the calculation of the gamma-ray flux from possible sources of dark matter annihilation or decay and show examples of limits which have been calculated using these techniques.

  10. Research in cosmic and gamma ray astrophysics

    NASA Technical Reports Server (NTRS)

    Stone, E. C.; Davis, L., Jr.; Mewaldt, R. A.; Prince, T. A.

    1989-01-01

    Research activities in cosmic rays, gamma rays, and astrophysical plasmas are covered. The activities are divided into sections and described, followed by a bibliography. The astrophysical aspects of cosmic rays, gamma rays, and of the radiation and electromagnetic field environment of the Earth and other planets are investigated. These investigations are performed by means of energetic particle and photon detector systems flown on spacecraft and balloons.

  11. Gamma-ray constraints on supernova nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Leising, Mark D.

    1994-01-01

    Gamma-ray spectroscopy holds great promise for probing nucleosynthesis in individual supernova explosions via short-lived radioactivity, and for measuring current global Galactic supernova nucleosynthesis with longer-lived radioactivity. It was somewhat surprising that the former case was realized first for a Type II supernova, when both Co-56 and Co-57 were detected in SN 1987A. These provide unprecedented constraints on models of Type II explosions and nucleosynthesis. Live Al-26 in the Galaxy might come from Type II supernovae, and if it is eventually shown to be so, can constrain massive star evolution, supernova nucleosynthesis, and the Galactic Type II supernova rate. Type Ia supernovae, thought to be thermonuclear explosions, have not yet been detected in gamma-rays. This is somewhat surprising given current models and recent Co-56 detection attempts. Ultimately, gamma-ray measurements can confirm their thermonuclear nature, probe the nuclear burning conditions, and help evaluate their contributions to Galactic nucleosynthesis. Type Ib/c supernovae are poorly understood. Whether they are core collapse or thermonuclear events might be ultimately settled by gamma-ray observations. Depending on details of the nuclear processing, any of these supernova types might contribute to a detectable diffuse glow of Fe-60 gamma-ray lines. Previous attempts at detection have come very close to expected emission levels. Remnants of any type of age less that a few centuries might be detectable as individual spots of Ti-44 gamma-ray line emission. It is in fact quite surprising that previous surveys have not discovered such spots, and the constraints on the combination of nucleosynthesis yields and supernova rates are very interesting. All of these interesting limits and possibilities mean that the next mission, International Gamma-Ray Astrophysics Laboratory (INTEGRAL), if it has sufficient sensitivity, is very likely to lead to the realization of much of the great potential

  12. The Mystery of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    1998-01-01

    Gamma-ray bursts remain on of the greatest mysteries in astrophysics in spite of recent observational advances and intense theoretical work. Although some of the basic properties of bursts were known 25 years ago, new and more detailed observations have been made by the BATSE (Burst and Transient Source Experiment) experiment on the Compton Gamma Ray Observatory in the past five years. Recent observations of bursts and some proposed models will be discussed.

  13. Fermi Sees the Gamma Ray Sky

    NASA Image and Video Library

    2017-09-28

    This view of the gamma-ray sky constructed from one year of Fermi LAT observations is the best view of the extreme universe to date. The map shows the rate at which the LAT detects gamma rays with energies above 300 million electron volts -- about 120 million times the energy of visible light -- from different sky directions. Brighter colors equal higher rates. Credit: NASA/DOE/Fermi LAT Collaboration Full story: www.nasa.gov/mission_pages/GLAST/news/first_year.html

  14. Gamma -radiations connected to atmospheric precipitations

    NASA Astrophysics Data System (ADS)

    Vashenyuk, Eduard; Balabin, Yury; Gvozdevsky, Boris; Germanenko, Alexey

    Since 2008 we are monitoring the gamma -radiation in surface layer of atmosphere with scin-tillation gamma -spectrometers. Instruments consist of a crystal NaI (Tl), a photomultiplier and a pulse amplifier. The data are transmitted to a computer with a special card with the 4096 channel pulse-amplitude analyzer. The gamma-ray monitoring is presently carried out at two high-latitude points: Apatity (N 65.57, E 33.39) and Barentsburg, Spitsbergen(N 78.06, E 14.22). The detectors in Apatity and Barentsburg are covered from sides and bottom by metallic screen for shielding them from environmental radiations from a building and ground. Together with gamma-spectrometer in Apatity a precipitation measuring device (PMD) was installed, which allows us to estimate presence and intensity of precipitations. Information about precipitations in Barentsburg was taken from the local meteorological observatory. The observations have shown that sporadic increases of gamma -radiation registered by spectrome-ters are almost always accompanied by intensive precipitations (rain, snowfall). The measured spectrum of gamma -radiation was rather smooth and did not show peaks in a range from 1 up to 200 KeV. Two basic hypotheses of an origin of high-energy photons during precipitations are discussed. The first is probable connection with atmospheric radionuclides, which are at-tached to aerosols and are taken out from the atmosphere by precipitations (rain and snow). Against this hypothesis speaks lack of peaks on gamma-ray spectrum. The gamma-spectrum from radionuclides usually has characteristic and expressed spectral lines. The second probable cause is x-ray radiation arising at deceleration in air of free electrons, accelerated in an electric field between clouds and ground. All cases of precipitations are accompanied by dense cloudi-ness and strengthening of an atmospheric electric field. The arguments for this mechanism are resulted.

  15. Supernovae and gamma-ray bursts connection

    SciTech Connect

    Valle, Massimo Della

    2015-12-17

    I’ll review the status of the Supernova/Gamma-Ray Burst connection. Several pieces of evidence suggest that long duration Gamma-ray Bursts are associated with bright SNe-Ic. However recent works suggest that GRBs might be produced in tight binary systems composed of a massive carbon-oxygen cores and a neutron star companion. Current estimates of the SN and GRB rates yield a ratio GRB/SNe-Ibc in the range ∼ 0.4% − 3%.

  16. Gamma-ray Albedo of the Moon

    SciTech Connect

    Moskalenko, Igor V.; Porter, Troy A.

    2007-06-14

    We use the GEANT4 Monte Carlo framework to calculate the gamma-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of gamma-rays from the Moon is very steep with an effective cutoff around 3 GeV (600 MeV for the inner part of the Moon disc). Since it is the only (almost) black spot in the gamma-ray sky, it provides a unique opportunity for calibration of gamma-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). The albedo flux depends on the incident CR spectrum which changes over the solar cycle. Therefore, it is possible to monitor the CR spectrum using the albedo gamma-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo -rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the GLAST LAT to monitor the CR spectrum near the Earth beyond the lifetime of PAMELA.

  17. Gamma Putty dosimetric studies in electron beam

    PubMed Central

    Gloi, Aime M.

    2016-01-01

    Traditionally, lead has been used for field shaping in megavoltage electron beams in radiation therapy. In this study, we analyze the dosimetric parameters of a nontoxic, high atomic number (Z = 83), bismuth-loaded material called Gamma Putty that is malleable and can be easily molded to any desired shape. First, we placed an ionization chamber at different depths in a solid water phantom under a Gamma Putty shield of thickness (t = 0, 3, 5, 10, 15, 20, and 25 mm, respectively) and measured the ionizing radiation on the central axis (CAX) for electron beam ranging in energies from 6 to 20 MeV. Next, we investigated the relationship between the relative ionization (RI) measured at a fixed depth for several Gamma Putty shield at different cutout diameters ranging from 2 to 5 cm for various beam energies and derived an exponential fitting equation for clinical purposes. The dose profiles along the CAX show that bremsstrahlung dominates for Gamma Putty thickness >15 mm. For high-energy beams (12–20 MeV) and all Gamma Putty thicknesses up to 25 mm, RI below 5% could not be achieved due to the strong bremsstrahlung component. However, Gamma Putty is a very suitable material for reducing the transmission factor below 5% and protecting underlying normal tissues for low-energy electron beams (6–9 MeV). PMID:27651563

  18. Shock response of a gamma titanium aluminide

    SciTech Connect

    Shazly, Mostafa; Prakash, Vikas

    2008-10-15

    Potential use of {gamma}-TiAl alloys in aerospace and other structural applications require knowledge of their impact behavior for better evaluation and modeling. In the present study plate impact experiments are conducted using a single-stage gas gun to better understand the shock behavior of the recently developed class of gamma titanium aluminide alloys--the Gamma-Met PX. The Gamma-Met PX showed superior shock properties when compared to the conventional titanium aluminide alloys. The spall strength of Gamma-Met PX is 1.8{+-}0.09 GPa, which is four to six times higher than those reported for other gamma titanium aluminide alloys. Moreover, it has a Hugoniot elastic limit of 1.88 GPa at a target thickness of 3.86 mm, which drops to 1.15 GPa at target thickness of 15.8 mm. The decay in the elastic precursor is continuous without showing an asymptote to a constant level within the range of target thicknesses studied.

  19. Molecular recognition of nitrated fatty acids by PPAR[gamma

    SciTech Connect

    Li, Yong; Zhang, Jifeng; Schopfer, Francisco J.; Martynowski, Dariusz; Garcia-Barrio, Minerva T.; Kovach, Amanda; Suino-Powell, Kelly; Baker, Paul R.S.; Freeman, Bruce A.; Chen, Y. Eugene; Xu, H. Eric

    2010-03-08

    Peroxisome proliferator activated receptor-{gamma} (PPAR{gamma}) regulates metabolic homeostasis and adipocyte differentiation, and it is activated by oxidized and nitrated fatty acids. Here we report the crystal structure of the PPAR{gamma} ligand binding domain bound to nitrated linoleic acid, a potent endogenous ligand of PPAR{gamma}. Structural and functional studies of receptor-ligand interactions reveal the molecular basis of PPAR{gamma} discrimination of various naturally occurring fatty acid derivatives.

  20. Mercuric iodine room temperature gamma-ray detectors

    NASA Technical Reports Server (NTRS)

    Patt, Bradley E.; Markakis, Jeffrey M.; Gerrish, Vernon M.; Haymes, Robert C.; Trombka, Jacob I.

    1990-01-01

    high resolution mercuric iodide room temperature gamma-ray detectors have excellent potential as an essential component of space instruments to be used for high energy astrophysics. Mercuric iodide detectors are being developed both as photodetectors used in combination with scintillation crystals to detect gamma-rays, and as direct gamma-ray detectors. These detectors are highly radiation damage resistant. The list of applications includes gamma-ray burst detection, gamma-ray line astronomy, solar flare studies, and elemental analysis.

  1. Mercuric iodine room temperature gamma-ray detectors

    NASA Technical Reports Server (NTRS)

    Patt, Bradley E.; Markakis, Jeffrey M.; Gerrish, Vernon M.; Haymes, Robert C.; Trombka, Jacob I.

    1990-01-01

    high resolution mercuric iodide room temperature gamma-ray detectors have excellent potential as an essential component of space instruments to be used for high energy astrophysics. Mercuric iodide detectors are being developed both as photodetectors used in combination with scintillation crystals to detect gamma-rays, and as direct gamma-ray detectors. These detectors are highly radiation damage resistant. The list of applications includes gamma-ray burst detection, gamma-ray line astronomy, solar flare studies, and elemental analysis.

  2. Predicting diffusion paths and interface motion in gamma/gamma + beta, Ni-Cr-Al diffusion couples

    NASA Technical Reports Server (NTRS)

    Nesbitt, J. A.; Heckel, R. W.

    1987-01-01

    A simplified model has been developed to predict Beta recession and diffusion paths in ternary gamma/gamma + beta diffusion couples (gamma:fcc, beta: NiAl structure). The model was tested by predicting beta recession and diffusion paths for four gamma/gamma + beta, Ni-Cr-Al couples annealed for 100 hours at 1200 C. The model predicted beta recession within 20 percent of that measured for each of the couples. The model also predicted shifts in the concentration of the gamma phase at the gamma/gamma + beta interface within 2 at. pct Al and 6 at. pct Cr of that measured in each of the couples. A qualitative explanation based on simple kinetic and mass balance arguments has been given which demonstrates the necessity for diffusion in the two-phase region of certain gamma/gamma + beta, Ni-Cr-Al couples.

  3. Gamma ray astrophysics to the year 2000. Report of the NASA Gamma Ray Program Working Group

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Important developments in gamma-ray astrophysics up to energies of 100 GeV during the last decade are reviewed. Also, the report seeks to define the major current scientific goals of the field and proposes a vigorous program to pursue them, extending to the year 2000. The goals of gamma-ray astronomy include the study of gamma rays which provide the most direct means of studying many important problems in high energy astrophysics including explosive nucleosynthesis, accelerated particle interactions and sources, and high-energy processes around compact objects. The current research program in gamma-ray astronomy in the U.S. including the space program, balloon program and foreign programs in gamma-ray astronomy is described. The high priority recommendations for future study include an Explorer-class high resolution gamma-ray spectroscopy mission and a Get Away Special cannister (GAS-can) or Scout class multiwavelength experiment for the study of gamma-ray bursts. Continuing programs include an extended Gamma Ray Observatory mission, continuation of the vigorous program of balloon observations of the nearby Supernova 1987A, augmentation of the balloon program to provide for new instruments and rapid scientific results, and continuation of support for theoretical research. Long term recommendations include new space missions using advanced detectors to better study gamma-ray sources, the development of these detectors, continued study for the assembly of large detectors in space, collaboration with the gamma-ray astronomy missions initiated by other countries, and consideration of the Space Station attached payloads for gamma-ray experiments.

  4. Supernovae and Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Panagia, Nino; Sahu, Kailash

    2001-07-01

    Participants; Preface; Gamma-ray burst-supernova relation B. Paczynski; Observations of gamma-ray bursts G. Fishman; Fireballs T. Piran; Gamma-ray mechanisms M. Rees; Prompt optical emission from gamma-ray bursts R. Kehoe, C. Akerlof, R. Balsano, S. Barthelmy, J. Bloch, P. Butterworth, D. Casperson, T. Cline, S. Fletcher, F. Frontera, G. Gisler, J. Heise, J. Hills, K. Hurley, B. Lee, S. Marshall, T. McKay, A. Pawl, L. Piro, B. Priedhorsky, J. Szymanski and J. Wren; X-ray afterglows of gamma-ray bursts L. Piro; The first year of optical-IR observations of SN1998bw I. Danziger, T. Augusteijn, J. Brewer, E. Cappellaro, V. Doublier, T. Galama, J. Gonzalez, O. Hainaut, B. Leibundgut, C. Lidman, P. Mazzali, K. Nomoto, F. Patat, J. Spyromilio, M. Turatto, J. Van Paradijs, P. Vreeswijk and J. Walsh; X-ray emission of Supernova 1998bw in the error box of GRB980425 E. Pian; Direct analysis of spectra of type Ic supernovae D. Branch; The interaction of supernovae and gamma-ray bursts with their surroundings R. Chevalier; Magnetars, soft gamma-ray repeaters and gamma-ray bursts A. Harding; Super-luminous supernova remnants Y. -H. Chu, C. -H. Chen and S. -P. Lai; The properties of hypernovae: SNe Ic 1998bw, 1997ef, and SN IIn 1997cy K. Nomoto, P. Mazzali, T. Nakamura, K. Iwanmoto, K. Maeda, T. Suzuki, M. Turatto, I. Danziger and F. Patat; Collapsars, Gamma-Ray Bursts, and Supernovae S. Woosley, A. MacFadyen and A. Heger; Pre-supernova evolution of massive stars N. Panagia and G. Bono; Radio supernovae and GRB 980425 K. Weiler, N. Panagia, R. Sramek, S. Van Dyk, M. Montes and C. Lacey; Models for Ia supernovae and evolutionary effects P. Hoflich and I. Dominguez; Deflagration to detonation A. Khokhlov; Universality in SN Iae and the Phillips relation D. Arnett; Abundances from supernovae F. -K. Thielemann, F. Brachwitz, C. Freiburghaus, S. Rosswog, K. Iwamoto, T. Nakamura, K. Nomoto, H. Umeda, K. Langanke, G. Martinez-Pinedo, D. Dean, W. Hix and M. Strayer; Sne, GRBs, and the

  5. Gamma-Ray Imaging Probes.

    NASA Astrophysics Data System (ADS)

    Wild, Walter James

    1988-12-01

    External nuclear medicine diagnostic imaging of early primary and metastatic lung cancer tumors is difficult due to the poor sensitivity and resolution of existing gamma cameras. Nonimaging counting detectors used for internal tumor detection give ambiguous results because distant background variations are difficult to discriminate from neighboring tumor sites. This suggests that an internal imaging nuclear medicine probe, particularly an esophageal probe, may be advantageously used to detect small tumors because of the ability to discriminate against background variations and the capability to get close to sites neighboring the esophagus. The design, theory of operation, preliminary bench tests, characterization of noise behavior and optimization of such an imaging probe is the central theme of this work. The central concept lies in the representation of the aperture shell by a sequence of binary digits. This, coupled with the mode of operation which is data encoding within an axial slice of space, leads to the fundamental imaging equation in which the coding operation is conveniently described by a circulant matrix operator. The coding/decoding process is a classic coded-aperture problem, and various estimators to achieve decoding are discussed. Some estimators require a priori information about the object (or object class) being imaged; the only unbiased estimator that does not impose this requirement is the simple inverse-matrix operator. The effects of noise on the estimate (or reconstruction) is discussed for general noise models and various codes/decoding operators. The choice of an optimal aperture for detector count times of clinical relevance is examined using a statistical class-separability formalism.

  6. Automated Gamma Knife dose planning

    NASA Astrophysics Data System (ADS)

    Leichtman, Gregg S.; Aita, Anthony L.; Goldman, H. W.

    1998-06-01

    The Gamma Knife (Elekta Instruments, Inc., Atlanta, GA), a neurosurgical, highly focused radiation delivery device, is used to eradicate deep-seated anomalous tissue within the human brain by delivering a lethal dose of radiation to target tissue. This dose is the accumulated result of delivering sequential `shots' of radiation to the target where each shot is approximately 3D Gaussian in shape. The size and intensity of each shot can be adjusted by varying the time of radiation exposure and by using one of four collimator sizes ranging from 4 - 18 mm. Current dose planning requires that the dose plan be developed manually to cover the target, and only the target, with a desired minimum radiation intensity using a minimum number of shots. This is a laborious and subjective process which typically leads to suboptimal conformal target coverage by the dose. We have used adaptive simulated annealing/quenching followed by Nelder-Mead simplex optimization to automate the selection and placement of Gaussian-based `shots' to form a simulated dose plane. In order to make the computation of the problem tractable, the algorithm, based upon contouring and polygon clipping, takes a 2 1/2-D approach to defining the cost function. Several experiments have been performed where the optimizers have been given the freedom to vary the number of shots and the weight, collimator size, and 3D location of each shot. To data best results have been obtained by forcing the optimizers to use a fixed number of unweighted shots with each optimizer set free to vary the 3D location and collimator size of each shot. Our preliminary results indicate that this technology will radically decrease planning time while significantly increasing accuracy of conformal target coverage and reproducibility over current manual methods.

  7. Hardening anisotropy of {gamma}/{gamma}{prime} superalloy single crystals. 2: Numerical analysis of heterogeneity effects

    SciTech Connect

    Estevez, R.; Hoinard, G.; Franciosi, P.

    1997-04-01

    In the first part of this study, the {gamma}/{gamma}{prime} superalloy single crystals yield stress and hardening anisotropy were experimentally estimated at 650 C, assuming homogeneous plasticity, G. Hoinard, R. Estevez and P. Franciosi, Acta Metall. 43, 1593 (1995). Here alloy morphology is regarded in two different ways: first as a two-phase anisotropic material with a uniform {gamma} matrix, describing the {gamma}{prime} precipitates arrangement with the help of an elementary pattern of inclusions; then treating the {gamma} matrix as a three (geometrical) phase medium, i.e., the three families of orthogonal {gamma} layers separating the precipitates, to estimate the matrix behavior heterogeneity in a 4-phase modelling of the alloy. Both {gamma} and {gamma}{prime} phases are treated as elastic-plastic crystalline media deforming by octahedral and cubic slip, and the models are based on the self consistent approximation. The alloy elasticity limit, internal stresses and hardening anisotropy are discussed with regard to the chosen behavior description for each phase, and behavior simulations are compared to experimental information.

  8. High-energy gamma-ray studying with GAMMA-400 after Fermi-LAT

    NASA Astrophysics Data System (ADS)

    Topchiev, N. P.; Galper, A. M.; Bonvicini, V.; Adriani, O.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Bakaldin, A. V.; Bobkov, S. G.; Boezio, M.; Dalkarov, O. D.; Egorov, A. E.; Gorbunov, M. S.; Gusakov, Yu V.; Hnatyk, B. I.; Kadilin, V. V.; Kaplin, V. A.; Kheymits, M. D.; Korepanov, V. E.; Leonov, A. A.; Longo, F.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Moskalenko, I. V.; Naumov, P. Yu; Picozza, P.; Runtso, M. F.; Serdin, O. V.; Sparvoli, R.; Spillantini, P.; Stozhkov, Yu I.; Suchkov, S. I.; Taraskin, A. A.; Tavani, M.; Yurkin, Yu T.; Zverev, V. G.

    2017-01-01

    Fermi-LAT has made a significant contribution to the study of high-energy gamma-ray diffuse emission and the observation of ∼3000 discrete sources. However, one third of all gamma-ray sources (both galactic and extragalactic) are unidentified, the data on the diffuse gamma-ray emission should be clarified, and signatures of dark matter particles in the high-energy gamma-ray range are not observed up to now. GAMMA-400, currently developing gamma-ray telescope, will have the angular (∼0.01° at 100 GeV) and energy (∼1% at 100 GeV) resolutions in the energy range of 10-1000 GeV better than the Fermi-LAT (as well as ground gamma-ray telescopes) by a factor of 5-10 and observe some regions of the Universe (such as Galactic Center, Fermi Bubbles, Crab, Cygnus, etc.) in the highly elliptic orbit (without shading the telescope by the Earth) continuously for a long time. It will permit to identify many discrete sources, to clarify the structure of extended sources, to specify the data on the diffuse emission, and to resolve gamma rays from dark matter particles.

  9. Perspectives of the GAMMA-400 space observatory for high-energy gamma rays and cosmic rays measurements

    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, S.; 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.; 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.; Men'shenin, A. L.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu; Papini, P.; 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.; Yurkin, Yu T.; Zampa, N.; Zirakashvili, V. N.; Zverev, V. G.

    2016-02-01

    The GAMMA-400 gamma-ray telescope is intended to measure the fluxes of gamma-rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. Such measurements concern the following scientific tasks: investigation of point sources of gamma-rays, studies of the energy spectra of Galactic and extragalactic diffuse emission, studies of gamma-ray bursts and gamma-ray emission from the Sun, as well as high precision measurements of spectra of high-energy electrons and positrons. Also the GAMMA- 400 instrument provides the possibility for protons and nuclei measurements up to knee. But the main goal for the GAMMA-400 mission is to perform a sensitive search for signatures of dark matter particles in high-energy gamma-ray emission. To fulfill these measurements the GAMMA-400 gamma-ray telescope possesses unique physical characteristics in comparison with previous and present experiments. The major advantage of the GAMMA-400 instrument is excellent angular and energy resolution for gamma-rays above 10 GeV. The GAMMA-400 experiment will be installed onboard of the Navigator space platform, manufactured by the NPO Lavochkin Association. The expected orbit will be a highly elliptical orbit (with apogee 300.000 km and perigee 500 km) with 7 days orbital period. An important profit of such an orbit is the fact that the full sky coverage will always be available for gamma ray astronomy.

  10. Dual Gamma Neutron Directional Elpasolite Detector

    SciTech Connect

    Guss, P. P.; Mukhopadhyay, S.

    2013-09-01

    Some applications, particularly in homeland security, require detection of both neutron and gamma radiation. Typically, this is accomplished with a combination of two detectors registering neutrons and gammas separately. We have investigated a new type of neutron/gamma (n/γ) directional detection capability. We explored a new class of scintillator, cerium (Ce)-doped Elpasolites such as Cs2LiYCl6:Ce (CLYC), Cs2LiLaCl6 (CLLC), Cs2LiLaBr6:Ce (CLLB), or Cs2LiYBr6:Ce (CLYB). These materials are capable of providing energy resolution as good as 2.9% at 662 keV (FWHM), which is better than that of NaI:Tl. Because they contain 6Li, Elpasolites can also detect thermal neutrons. In the energy spectra, the full energy thermal neutron peak appears near or above 3 GEEn MeV. Thus, very effective pulse height discrimination is possible. In addition, the core-to-valence luminescence (CVL) provides Elpasolites with different temporal responses under gamma and neutron excitation, and, therefore, may be exploited for effective pulse shape discrimination. For instance, the CLLC emission consists of two main components: (1) CVL spanning from 220 nm to 320 nm and (2) Ce emission found in the range of 350 to 500 nm. The former emission is of particular interest because it appears only under gamma excitation. It is also very fast, decaying with a 2 ns time constant. The n/γ discrimination capability of Elpasolite detectors may be optimized by tuning the cerium doping content for maximum effect on n/γ pulse shape differences. The resulting Elpasolite detectors have the ability to collect neutron and gamma data simultaneously, with excellent discrimination. Further, an array of four of these Elpasolites detectors will perform directional detection in both the neutron and gamma channels simultaneously.

  11. New insights from cosmic gamma rays

    NASA Astrophysics Data System (ADS)

    Roland, Diehl

    2016-04-01

    The measurement of gamma rays from cosmic sources at ~MeV energies is one of the key tools for nuclear astrophysics, in its study of nuclear reactions and their impacts on objects and phenomena throughout the universe. Gamma rays trace nuclear processes most directly, as they originate from nuclear transitions following radioactive decays or high-energy collisions with excitation of nuclei. Additionally, the unique gamma-ray signature from the annihilation of positrons falls into this astronomical window and is discussed here: Cosmic positrons are often produced from β-decays, thus also of nuclear physics origins. The nuclear reactions leading to radioactive isotopes occur inside stars and stellar explosions, which therefore constitute the main objects of such studies. In recent years, both thermonuclear and core-collapse supernova radioactivities have been measured though 56Ni, 56Co, and 44Ti lines, and a beginning has thus been made to complement conventional supernova observations with such measurements of the prime energy sources of supernova light created in their deep interiors. The diffuse radioactive afterglow of massive-star nucleosynthesis in gamma rays is now being exploited towards astrophysical studies on how massive stars feed back their energy and ejecta into interstellar gas, as part of the cosmic cycle of matter through generations of stars enriching the interstellar gas and stars with metals. Large interstellar cavities and superbubbles have been recognised to be the dominating structures where new massive-star ejecta are injected, from 26Al gamma-ray spectroscopy. Also, constraints on the complex interiors of stars derive from the ratio of 60Fe/26Al gamma rays. Finally, the puzzling bulge-dominated intensity distribution of positron annihilation gamma rays is measured in greater detail, but still not understood; a recent microquasar flare provided evidence that such objects may be prime sources for positrons in interstellar space, rather than

  12. Human Gamma Oscillations during Slow Wave Sleep

    PubMed Central

    Valderrama, Mario; Crépon, Benoît; Botella-Soler, Vicente; Martinerie, Jacques; Hasboun, Dominique; Alvarado-Rojas, Catalina; Baulac, Michel; Adam, Claude; Navarro, Vincent; Le Van Quyen, Michel

    2012-01-01

    Neocortical local field potentials have shown that gamma oscillations occur spontaneously during slow-wave sleep (SWS). At the macroscopic EEG level in the human brain, no evidences were reported so far. In this study, by using simultaneous scalp and intracranial EEG recordings in 20 epileptic subjects, we examined gamma oscillations in cerebral cortex during SWS. We report that gamma oscillations in low (30–50 Hz) and high (60–120 Hz) frequency bands recurrently emerged in all investigated regions and their amplitudes coincided with specific phases of the cortical slow wave. In most of the cases, multiple oscillatory bursts in different frequency bands from 30 to 120 Hz were correlated with positive peaks of scalp slow waves (“IN-phase” pattern), confirming previous animal findings. In addition, we report another gamma pattern that appears preferentially during the negative phase of the slow wave (“ANTI-phase” pattern). This new pattern presented dominant peaks in the high gamma range and was preferentially expressed in the temporal cortex. Finally, we found that the spatial coherence between cortical sites exhibiting gamma activities was local and fell off quickly when computed between distant sites. Overall, these results provide the first human evidences that gamma oscillations can be observed in macroscopic EEG recordings during sleep. They support the concept that these high-frequency activities might be associated with phasic increases of neural activity during slow oscillations. Such patterned activity in the sleeping brain could play a role in off-line processing of cortical networks. PMID:22496749

  13. Investigation of {gamma} radiation from {sup 178}Hf in the respective (n, n Prime {gamma}) reaction

    SciTech Connect

    Govor, L. I.; Demidov, A. M.; Kurkin, V. A. Mikhailov, I. V.

    2012-12-15

    The spectra and angular distributions of gamma rays were measured in the reaction {sup 178}Hf(n, n Prime {gamma}) induced by a beam of fast reactor neutrons. Data onmultipole mixtures in gamma transitions and a lot of new information about gamma transitions of energy 1.5 to 3.0 MeV were obtained. A comparison of these results with information known from the respective (n, {gamma}) reaction made it possible to refine the schemes of deexcitation of {sup 178}Hf levels at energies above 1.5 MeV, to determine more precisely features of these levels, and to introduce new levels and rotation bands at excitation energies of about 2MeV.

  14. Gamma response study of radiation sensitive MOSFETs for their use as gamma radiation sensor

    SciTech Connect

    Srivastava, Saurabh; Kumar, A. Vinod; Aggarwal, Bharti; Singh, Arvind; Topkar, Anita

    2016-05-23

    Continuous monitoring of gamma dose is important in various fields like radiation therapy, space-related research, nuclear energy programs and high energy physics experiment facilities. The present work is focused on utilization of radiation-sensitive Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) to monitor gamma radiation doses. Static characterization of these detectors was performed to check their expected current-voltage relationship. Threshold voltage and transconductance per unit gate to source voltage (K factor) were calculated from the experimental data. The detector was exposed to gamma radiation in both, with and without gate bias voltage conditions, and change in threshold voltage was monitored at different gamma doses. The experimental data was fitted to obtain equation for dependence of threshold voltage on gamma dose. More than ten times increase in sensitivity was observed in biased condition (+3 V) compared to the unbiased case.

  15. Gamma response study of radiation sensitive MOSFETs for their use as gamma radiation sensor

    NASA Astrophysics Data System (ADS)

    Srivastava, Saurabh; Aggarwal, Bharti; Singh, Arvind; Kumar, A. Vinod; Topkar, Anita

    2016-05-01

    Continuous monitoring of gamma dose is important in various fields like radiation therapy, space-related research, nuclear energy programs and high energy physics experiment facilities. The present work is focused on utilization of radiation-sensitive Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) to monitor gamma radiation doses. Static characterization of these detectors was performed to check their expected current-voltage relationship. Threshold voltage and transconductance per unit gate to source voltage (K factor) were calculated from the experimental data. The detector was exposed to gamma radiation in both, with and without gate bias voltage conditions, and change in threshold voltage was monitored at different gamma doses. The experimental data was fitted to obtain equation for dependence of threshold voltage on gamma dose. More than ten times increase in sensitivity was observed in biased condition (+3 V) compared to the unbiased case.

  16. Evaluation of gamma interferon (IFN-gamma)-induced protein 10 (IP-10) responses for detection of cattle infected with Mycobacterium bovis: comparisons to IFN-gamma responses

    USDA-ARS?s Scientific Manuscript database

    Gamma interferon (IFN-gamma)-induced protein 10 (IP-10) has recently shown promise as a diagnostic biomarker of Mycobacterium tuberculosis infection of humans. The aim of the current study was to compare IP-10 and IFN-gamma responses upon Mycobacterium bovis infection in cattle using archived sample...

  17. Gamma-ray Output Spectra from 239 Pu Fission

    DOE PAGES

    Ullmann, John

    2015-05-25

    The gamma-ray multiplicities, individual gamma-ray energy spectra, and total gamma energy spectra following neutron-induced fission of 239Pu were measured using the DANCE detector at Los Alamos. Corrections for detector response were made using a forward-modeling technique based on propagating sets of gamma rays generated from a paramaterized model through a GEANT model of the DANCE array and adjusting the parameters for best fit to the measured spectra. The results for the gamma-ray spectrum and multiplicity are in general agreement with previous results, but the measured total gamma-ray energy is about 10% higher. We found that a dependence of the gamma-raymore » spectrum on the gamma-ray multplicity was also observed. Finally, global model calculations of the multiplicity and gamma energy distributions are in good agreement with the data, but predict a slightly softer total-energy distribution.« less

  18. Future Prospects for Space-Based Gamma Ray Astronomy

    NASA Astrophysics Data System (ADS)

    McConnell, Mark

    2015-04-01

    The gamma-ray sky offers a unique view into broad range of astrophysical phenomena, from nearby solar flares, to galactic pulsars, to gamma-ray bursts at the furthest reaches of the Universe. The Fermi mission has dramatically demonstrated the broad range of topics that can be addressed by gamma-ray observations. The full range of gamma-ray energies is quite broad, covering the electromagnetic spectrum at energies above about 100 keV. The energy range below several hundred GeV is the domain of space-based gamma-ray observatories, a range that is not completely covered by the Fermi LAT instrument. The gamma ray community has recently embarked on an effort to define the next steps for space-based gamma ray astronomy. These discussions are being facilitated through the Gamma-ray Science Interest Group (GammaSIG), which exists to provide community input to NASA in regards to current and future needs of the gamma-ray astrophysics community. The GammaSIG, as a part of the Physics of the Cosmos Program Analysis Group, provides a forum open to all members of the gamma-ray community. The GammaSIG is currently working to bring the community together with a common vision that will be expressed in the form of a community roadmap. This talk will summarize some of the latest results from active gamma ray observatories, including both Fermi and INTEGRAL, and will summarize the status of the community roadmap effort.

  19. Peroxisome proliferator activated receptor-gamma (PPAR-gamma) mediates the action of gamma linolenic acid in breast cancer cells.

    PubMed

    Jiang, W G; Redfern, A; Bryce, R P; Mansel, R E

    2000-02-01

    Gamma linolenic acid (GLA) is a polyunsaturated fatty acid, which induces cytotoxicity and regulates cell adhesion in cancer cells. The molecular mechanism of these actions is not clear. We have shown that GLA acts via peroxisome proliferator activated receptors (PPARs), by stimulating their phosphorylation and translocation to the nucleus. Removing PPAR gamma with antisense oligos abolished the effect of GLA on the expression of adhesion molecules and tumour suppressor genes, whereas removal of PPAR alpha had no effect. Tissues from patients with breast cancer showed a reduction of expression of both PPARs in cancer tissues, as compared with normal. Thus, PPAR gamma serves as the receptor for GLA in the regulation of gene expression in breast cancer cells.

  20. A simple gamma ray direction finder.

    PubMed

    Fujimoto, K

    2006-07-01

    One of the simplest gamma spectrometry systems that could provide the directional information of incident gamma rays has been developed. The system consists of a 3'' x 3'' phi NaI (Tl) scintillator, a specially shaped lead shield, and software. The measurement was carried out four times by rotating the shield position along the axis of the detector to obtain four energy spectra at one location. Four count rates at a special region of interest in the spectra were fed into the software for determining incident directions of gamma rays. Experiments using (137)Cs and (54)Mn at the same time demonstrated that the direction of gamma rays from several dominant sources from any direction could be identified with good precision by the total measurement time of 10 to 20 min. The system could be used to identify the locations of missing radioactive sources or the cause of elevation in ambient radiation dose rates. The disadvantages of the present system are follows: (1) It requires four time measurements at one location; (2) It can provide one pseudo incident angle when several contamination sources exist around the detector system and emit the same energy gamma rays; and (3) It can scan only one plane geometry that is usually chosen as the horizontal plane.

  1. Stellar Photon Archaeology with Gamma-Rays

    NASA Technical Reports Server (NTRS)

    Stecker, Floyd W.

    2009-01-01

    Ongoing deep surveys of galaxy luminosity distribution functions, spectral energy distributions and backwards evolution models of star formation rates can be used to calculate the past history of intergalactic photon densities and, from them, the present and past optical depth of the Universe to gamma-rays from pair production interactions with these photons. The energy-redshift dependence of the optical depth of the Universe to gamma-rays has become known as the Fazio-Stecker relation (Fazio & Stecker 1970). Stecker, Malkan & Scully have calculated the densities of intergalactic background light (IBL) photons of energies from 0.03 eV to the Lyman limit at 13.6 eV and for 0$ < z < $6, using deep survey galaxy observations from Spitzer, Hubble and GALEX and have consequently predicted spectral absorption features for extragalactic gamma-ray sources. This procedure can also be reversed. Determining the cutoff energies of gamma-ray sources with known redshifts using the recently launched Fermi gamma-ray space telescope may enable a more precise determination of the IBL photon densities in the past, i.e., the "archaeo-IBL.", and therefore allow a better measure of the past history of the total star formation rate, including that from galaxies too faint to be observed.

  2. Gamma-ray limits on neutrino lines

    SciTech Connect

    Queiroz, Farinaldo S.; Yaguna, Carlos E.; Weniger, Christoph

    2016-05-23

    Monochromatic neutrinos from dark matter annihilations (χχ→νν-bar) are always produced in association with a gamma-ray spectrum generated by electroweak bremsstrahlung. Consequently, these neutrino lines can be searched for not only with neutrino detectors but also indirectly with gamma-ray telescopes. Here, we derive limits on the dark matter annihilation cross section into neutrinos based on recent Fermi-LAT and HESS data. We find that, for dark matter masses above 200 GeV, gamma-ray data actually set the most stringent constraints on neutrino lines from dark matter annihilation and, therefore, an upper bound on the dark matter total annihilation cross section. In addition, we point out that gamma-ray telescopes, unlike neutrino detectors, have the potential to distinguish the flavor of the final state neutrino. Our results indicate that we have already entered into a new era where gamma-ray telescopes are more sensitive than neutrino detectors to neutrino lines from dark matter annihilation.

  3. Gamma radiation effects on peanut skin antioxidants.

    PubMed

    de Camargo, Adriano Costa; de Souza Vieira, Thais Maria Ferreira; Regitano-D'Arce, Marisa Aparecida Bismara; Calori-Domingues, Maria Antonia; Canniatti-Brazaca, Solange Guidolin

    2012-01-01

    Peanut skin, which is removed in the peanut blanching process, is rich in bioactive compounds with antioxidant properties. The aims of this study were to measure bioactive compounds in peanut skins and evaluate the effect of gamma radiation on their antioxidant activity. Peanut skin samples were treated with 0.0, 5.0, 7.5, or 10.0 kGy gamma rays. Total phenolics, condensed tannins, total flavonoids, and antioxidant activity were evaluated. Extracts obtained from the peanut skins were added to refined-bleached-deodorized (RBD) soybean oil. The oxidative stability of the oil samples was determined using the Oil Stability Index method and compared to a control and synthetic antioxidants (100 mg/kg BHT and 200 mg/kg TBHQ). Gamma radiation changed total phenolic content, total condensed tannins, total flavonoid content, and the antioxidant activity. All extracts, gamma irradiated or not, presented increasing induction period (h), measured by the Oil Stability Index method, when compared with the control. Antioxidant activity of the peanut skins was higher than BHT. The present study confirmed that gamma radiation did not affect the peanut skin extracts' antioxidative properties when added to soybean oil.

  4. Oligomerization of L-gamma-carboxyglutamic acid

    NASA Technical Reports Server (NTRS)

    Hill, A. R. Jr; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    1999-01-01

    Unlike glutamic acid, L-gamma-carboxyglutamic acid does not oligomerize efficiently when treated with carbonyldiimidazole in aqueous solution. However, divalent ions such as Mg2+ catalyze the reaction, and lead to the formation of oligomers in good yield. In the presence of hydroxylapatite, L-gamma-carboxyglutamic acid oligomerizes efficiently in a reaction that proceeds in the absence of divalent ions but is further catalyzed when they are present. After 'feeding' 50 times with activated amino acid in the presence of the Mg2+ ion, oligomers longer than the 20-mer could be detected. The effect of hydroxylapatite on peptide elongation is very sensitive to the nature of the activated amino acid and the acceptor peptide. Glutamic acid oligomerizes more efficiently than L-gamma-carboxyglutamic acid on hydroxylapatite and adds more efficiently to decaglutamic acid in solution. One might, therefore, expect that glutamic acid would add more efficiently than L-gamma-carboxyglutamic acid to decaglutamic acid on hydroxylapatite. The contrary is true--the addition of L-gamma-carboxyglutamic acid is substantially more efficient. This suggests that oligomerization on the surface of hydroxylapatite depends on the detailed match between the structure of the surface of the mineral and the structure of the oligomer.

  5. Short gamma-ray bursts: A review

    NASA Astrophysics Data System (ADS)

    D'Avanzo, P.

    2015-09-01

    Gamma-Ray Bursts (GRBs) are rapid, bright flashes of radiation peaking in the gamma-ray band occurring at an average rate of one event per day at cosmological distances. They are characterized by a collimated relativistic outflow pushing through the interstellar medium shining in gamma-rays powered by a central engine. This prompt phase is followed by a fading afterglow emission at longer wavelength, powered in part by the expanding outflow, and in part by continuous energy injection by the central engine. The observed evidences of supernovae associated to long GRBs (those with a duration of the gamma-ray emission > 2 s) brought to a general consensus on indicating the core collapse of massive stars as the progenitor of these events. Following the most accredited model, short GRBs (the events with a duration of the gamma-ray emission ≤ 2 s) originate from the coalescence of compact binary systems (two neutron stars or neutron star-black hole systems). This paper presents a review of the observational properties of short GRBs and shows how the study of these properties can be used as a tool to unveil their elusive progenitors and provide information on the nature of the central engine powering the observed emission. The increasing evidence for compact object binary progenitors makes short GRBs one of the most promising sources of gravitational waves for the forthcoming Advanced LIGO/Virgo experiments.

  6. Gamma Radiation Effects on Peanut Skin Antioxidants

    PubMed Central

    de Camargo, Adriano Costa; de Souza Vieira, Thais Maria Ferreira; Regitano-D’Arce, Marisa Aparecida Bismara; Calori-Domingues, Maria Antonia; Canniatti-Brazaca, Solange Guidolin

    2012-01-01

    Peanut skin, which is removed in the peanut blanching process, is rich in bioactive compounds with antioxidant properties. The aims of this study were to measure bioactive compounds in peanut skins and evaluate the effect of gamma radiation on their antioxidant activity. Peanut skin samples were treated with 0.0, 5.0, 7.5, or 10.0 kGy gamma rays. Total phenolics, condensed tannins, total flavonoids, and antioxidant activity were evaluated. Extracts obtained from the peanut skins were added to refined-bleached-deodorized (RBD) soybean oil. The oxidative stability of the oil samples was determined using the Oil Stability Index method and compared to a control and synthetic antioxidants (100 mg/kg BHT and 200 mg/kg TBHQ). Gamma radiation changed total phenolic content, total condensed tannins, total flavonoid content, and the antioxidant activity. All extracts, gamma irradiated or not, presented increasing induction period (h), measured by the Oil Stability Index method, when compared with the control. Antioxidant activity of the peanut skins was higher than BHT. The present study confirmed that gamma radiation did not affect the peanut skin extracts’ antioxidative properties when added to soybean oil. PMID:22489142

  7. Gamma Reaction History for the NIF

    SciTech Connect

    Herrmann, H W; Evans, S C; Kim, Y; Mack, J M; Young, C S; Cox, B C; Frogget, B C; Kaufman, M I; Malone, R M; Tunnell, T W; Stoeffl, W; Horsfield, C J

    2009-06-05

    Bang time and reaction history measurements are fundamental components of diagnosing ICF implosions and will be essential contributors to diagnosing attempts at ignition on the National Ignition Facility (NIF). Fusion gammas provide a direct measure of fusion interaction rate without being compromised by Doppler spreading. Gamma-based gas Cherenkov detectors that convert fusion gamma rays to optical Cherenkov photons for collection by fast recording systems have been developed and fielded at Omega. These systems have established their usefulness in illuminating ICF physics in several experimental campaigns. Bang time precision better than 25 ps has been demonstrated, well below the 50 ps accuracy requirement defined by the NIF System Design Requirements. A staged approach of implementing Gamma Reaction History (GRH) diagnostics on the NIF has been initiated. In the early stage, multiple detectors located close to target chamber center (at 2 and 6 m) and coupled to photomultiplier tubes are geared toward the loweryield THD campaign. In the later stage, streak camera–coupled instruments will be used for improved temporal resolution at the higher yields expected from the DT ignition campaign. Multiple detectors will allow for increased dynamic range and gamma energy spectral information.

  8. Oligomerization of L-gamma-carboxyglutamic acid.

    PubMed

    Hill, A R; Orgel, L E

    1999-03-01

    Unlike glutamic acid, L-gamma-carboxyglutamic acid does not oligomerize efficiently when treated with carbonyldiimidazole in aqueous solution. However, divalent ions such as Mg2+ catalyze the reaction, and lead to the formation of oligomers in good yield. In the presence of hydroxylapatite, L-gamma-carboxyglutamic acid oligomerizes efficiently in a reaction that proceeds in the absence of divalent ions but is further catalyzed when they are present. After 'feeding' 50 times with activated amino acid in the presence of the Mg2+ ion, oligomers longer than the 20-mer could be detected. The effect of hydroxylapatite on peptide elongation is very sensitive to the nature of the activated amino acid and the acceptor peptide. Glutamic acid oligomerizes more efficiently than L-gamma-carboxyglutamic acid on hydroxylapatite and adds more efficiently to decaglutamic acid in solution. One might, therefore, expect that glutamic acid would add more efficiently than L-gamma-carboxyglutamic acid to decaglutamic acid on hydroxylapatite. The contrary is true--the addition of L-gamma-carboxyglutamic acid is substantially more efficient. This suggests that oligomerization on the surface of hydroxylapatite depends on the detailed match between the structure of the surface of the mineral and the structure of the oligomer.

  9. High spins in gamma-soft nuclei

    SciTech Connect

    Leander, G.A.; Frauendorf, S.; May, F.R.

    1982-01-01

    Nuclei which are soft with respect to the ..gamma.. shape degree of freedom are expected to have many different structures coexisting in the near-yrast regime. In particular, the lowest rotational quasi-particle in a high-j shell exerts a strong polarizing effect on ..gamma... The ..gamma.. to which it drives is found to vary smoothly over a 180/sup 0/ range as the position of the Fermi level varies. This simple rule is seen to have a direct connection with the energy staggering of alternate spin states in rotational bands. A diagram is presented which provides a general theoretical reference for experimental tests of the relation between ..gamma.., spin staggering, configuration, and nucleon number. In a quasicontinuum spectrum, the coexistence of different structures are expected to make several unrelated features appear within any one slice of sum energy and multiplicity. However, it is also seen that the in-band moment of inertia may be similar for many bands of different ..gamma...

  10. Stellar Photon Archaeology with Gamma-Rays

    NASA Technical Reports Server (NTRS)

    Stecker, Floyd W.

    2009-01-01

    Ongoing deep surveys of galaxy luminosity distribution functions, spectral energy distributions and backwards evolution models of star formation rates can be used to calculate the past history of intergalactic photon densities and, from them, the present and past optical depth of the Universe to gamma-rays from pair production interactions with these photons. The energy-redshift dependence of the optical depth of the Universe to gamma-rays has become known as the Fazio-Stecker relation (Fazio & Stecker 1970). Stecker, Malkan & Scully have calculated the densities of intergalactic background light (IBL) photons of energies from 0.03 eV to the Lyman limit at 13.6 eV and for 0$ < z < $6, using deep survey galaxy observations from Spitzer, Hubble and GALEX and have consequently predicted spectral absorption features for extragalactic gamma-ray sources. This procedure can also be reversed. Determining the cutoff energies of gamma-ray sources with known redshifts using the recently launched Fermi gamma-ray space telescope may enable a more precise determination of the IBL photon densities in the past, i.e., the "archaeo-IBL.", and therefore allow a better measure of the past history of the total star formation rate, including that from galaxies too faint to be observed.

  11. Shock response of a gamma titanium aluminide

    NASA Astrophysics Data System (ADS)

    Shazly, Mostafa; Prakash, Vikas

    2008-10-01

    Potential use of γ-TiAl alloys in aerospace and other structural applications require knowledge of their impact behavior for better evaluation and modeling. In the present study plate impact experiments are conducted using a single-stage gas gun to better understand the shock behavior of the recently developed class of gamma titanium aluminide alloys—the Gamma-Met PX. The Gamma-Met PX showed superior shock properties when compared to the conventional titanium aluminide alloys. The spall strength of Gamma-Met PX is 1.8±0.09 GPa, which is four to six times higher than those reported for other gamma titanium aluminide alloys. Moreover, it has a Hugoniot elastic limit of 1.88 GPa at a target thickness of 3.86 mm, which drops to 1.15 GPa at target thickness of 15.8 mm. The decay in the elastic precursor is continuous without showing an asymptote to a constant level within the range of target thicknesses studied.

  12. Oligomerization of L-gamma-carboxyglutamic acid

    NASA Technical Reports Server (NTRS)

    Hill, A. R. Jr; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    1999-01-01

    Unlike glutamic acid, L-gamma-carboxyglutamic acid does not oligomerize efficiently when treated with carbonyldiimidazole in aqueous solution. However, divalent ions such as Mg2+ catalyze the reaction, and lead to the formation of oligomers in good yield. In the presence of hydroxylapatite, L-gamma-carboxyglutamic acid oligomerizes efficiently in a reaction that proceeds in the absence of divalent ions but is further catalyzed when they are present. After 'feeding' 50 times with activated amino acid in the presence of the Mg2+ ion, oligomers longer than the 20-mer could be detected. The effect of hydroxylapatite on peptide elongation is very sensitive to the nature of the activated amino acid and the acceptor peptide. Glutamic acid oligomerizes more efficiently than L-gamma-carboxyglutamic acid on hydroxylapatite and adds more efficiently to decaglutamic acid in solution. One might, therefore, expect that glutamic acid would add more efficiently than L-gamma-carboxyglutamic acid to decaglutamic acid on hydroxylapatite. The contrary is true--the addition of L-gamma-carboxyglutamic acid is substantially more efficient. This suggests that oligomerization on the surface of hydroxylapatite depends on the detailed match between the structure of the surface of the mineral and the structure of the oligomer.

  13. LUMINOSITY EVOLUTION OF GAMMA-RAY PULSARS

    SciTech Connect

    Hirotani, Kouichi

    2013-04-01

    We investigate the electrodynamic structure of a pulsar outer-magnetospheric particle accelerator and the resulting gamma-ray emission. By considering the condition for the accelerator to be self-sustained, we derive how the trans-magnetic-field thickness of the accelerator evolves with the pulsar age. It is found that the thickness is small but increases steadily if the neutron-star envelope is contaminated by sufficient light elements. For such a light element envelope, the gamma-ray luminosity of the accelerator is kept approximately constant as a function of age in the initial 10,000 yr, forming the lower bound of the observed distribution of the gamma-ray luminosity of rotation-powered pulsars. If the envelope consists of only heavy elements, on the other hand, the thickness is greater, but it increases less rapidly than a light element envelope. For such a heavy element envelope, the gamma-ray luminosity decreases relatively rapidly, forming the upper bound of the observed distribution. The gamma-ray luminosity of a general pulsar resides between these two extreme cases, reflecting the envelope composition and the magnetic inclination angle with respect to the rotation axis. The cutoff energy of the primary curvature emission is regulated below several GeV even for young pulsars because the gap thickness, and hence the acceleration electric field, is suppressed by the polarization of the produced pairs.

  14. Study of (178m2)hafnium(gamma, gamma')(178)hafnium reaction by nuclear spectroscopy methods

    NASA Astrophysics Data System (ADS)

    Rusu, Claudiu

    Controlled release of the energy stored in nuclear isomers is very attractive for producing powerful sources of induced gamma-ray radiation. High-energy nuclear isomers can have very long lifetimes of the order of years and thus they can serve as good energy storage media. For instance, 1 mg of the 178m2Hf isomer stores about 1 MJ as excitation energy of the isomeric state. One of the most promising ways to release the energy stored in the isomeric state involves photonuclear reactions in the energy range of soft X-rays. Photons with energies lower than 20 keV can excite the 178m2Hf isomeric state to an intermediate level from which gamma transitions cascade to lower levels with a decay rate much faster than the rate of spontaneous decay of the isomeric state. In this work, the photoexcitation of 178m2Hf by (gamma, gamma ') reactions at low energies was studied by nuclear spectroscopy methods. The experimental arrangement was based on the coincident detection of gamma photons with four large HPGe detectors. A bremsstrahlung X-ray generator was used as excitation source, which covered a continuous energy-range from 0 to 60 keV. The interpretation of the experimental results shows that the decay of the 178m2Hf isomer can be triggered by X-rays at a power on the order of only mW/cm 2. The analysis of the gamma-gamma coincidence data has revealed that during X-ray irradiations, a line of 129.5 keV was found in coincidence with the 213.4 keV ground state band (GSB) transition. The 129.5 keV line has not been previously observed and is not a known transition of the spontaneous decay of 178m2Hf. The 129.5 keV gamma transition must be a member of a sequence of gamma transitions that bypasses most of the normal decay cascade populated by spontaneous decay. This result leads to a deeper understanding of the (gamma, gamma ') reactions at low energies. These photonuclear reactions are of special interest because of the importance of possible practical applications. The studies

  15. Low radioactivity spectral gamma calibration facility

    SciTech Connect

    Mathews, M.A.; Bowman, H.R.; Huang, L., H.; Lavelle, M.J.; Smith, A.R.; Hearst, J.R.; Wollenberg, H.A.; Flexser, S.

    1986-01-01

    A low radioactivity calibration facility has been constructed at the Nevada Test Site (NTS). This facility has four calibration models of natural stone that are 3 ft in diameter and 6 ft long, with a 12 in. cored borehole in the center of each model and a lead-shielded run pipe below each model. These models have been analyzed by laboratory natural gamma ray spectroscopy (NGRS) and neutron activation analysis (NAA) for their K, U, and Th content. Also, 42 other elements were analyzed in the NAA. The /sup 222/Rn emanation data were collected. Calibrating the spectral gamma tool in this low radioactivity calibration facility allows the spectral gamma log to accurately aid in the recognition and mapping of subsurface stratigraphic units and alteration features associated with unusual concentrations of these radioactive elements, such as clay-rich zones.

  16. Gamma ray pulsars. [electron-photon cascades

    NASA Technical Reports Server (NTRS)

    Oegelman, H.; Ayasli, S.; Hacinliyan, A.

    1977-01-01

    Data from the SAS-2 high-energy gamma-ray experiment reveal the existence of four pulsars emitting photons above 35 MeV. An attempt is made to explain the gamma-ray emission from these pulsars in terms of an electron-photon cascade that develops in the magnetosphere of the pulsar. Although there is very little material above the surface of the pulsar, the very intense magnetic fields (10 to the 12th power gauss) correspond to many radiation lengths which cause electrons to emit photons by magnetic bremsstrahlung and which cause these photons to pair-produce. The cascade develops until the mean photon energy drops below the pair-production threshold which is in the gamma-ray range; at this stage, the photons break out from the source.

  17. Fuzzy correlations of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Hartmann, Dieter H.; Linder, Eric V.; Blumenthal, George R.

    1991-01-01

    The origin of gamma-ray bursts is not known, both in the sense of the nature of the source emitting the radiation and literally, the position of the burst on the sky. Lacking unambiguously identified counterparts in any wavelength band studied to date, statistical approaches are required to determine the burster distance scale. Angular correlation analysis is one of the most powerful tools in this regard. However, poor detector resolution gives large localization errors, effectively beam smearing the positions. The resulting fuzzy angular correlation function is investigated and the generic isotropization that smearing induces on any intrinsic clustering is discussed. In particular, the extent to which gamma-ray burst observations by the BATSE detector aboard the Gamma-Ray Observatory might recover an intrinsic source correlation is investigated.

  18. Gamma-Ray Imaging for Explosives Detection

    NASA Technical Reports Server (NTRS)

    deNolfo, G. A.; Hunter, S. D.; Barbier, L. M.; Link, J. T.; Son, S.; Floyd, S. R.; Guardala, N.; Skopec, M.; Stark, B.

    2008-01-01

    We describe a gamma-ray imaging camera (GIC) for active interrogation of explosives being developed by NASA/GSFC and NSWCICarderock. The GIC is based on the Three-dimensional Track Imager (3-DTI) technology developed at GSFC for gamma-ray astrophysics. The 3-DTI, a large volume time-projection chamber, provides accurate, approx.0.4 mm resolution, 3-D tracking of charged particles. The incident direction of gamma rays, E, > 6 MeV, are reconstructed from the momenta and energies of the electron-positron pair resulting from interactions in the 3-DTI volume. The optimization of the 3-DTI technology for this specific application and the performance of the GIC from laboratory tests is presented.

  19. Gamma ray lines from buried supernovae

    NASA Technical Reports Server (NTRS)

    Morfill, G. E.; Meyer, P.

    1982-01-01

    An investigation is conducted concerning the possibility that supernovae (SN), located in dense interstellar clouds, might become the sources of gamma ray lines. The SN progenitor, in such a case, has to be an O or B star so that its evolutionary lifetime is short, and an explosion inside the cloud is still possible. It is shown that, in principle, a measurement of the abundances in the ejecta is possible. Attention is given to the characteristics of a model, the expected luminosity of gamma-ray lines, and the study of specific numerical examples for testing the feasibility of the considered mechanism. On the basis of the obtained results, it is concluded that gamma-ray line production by collisional excitation in confined supernovae remnants may be quite important.

  20. SUB-LUMINOUS {gamma}-RAY PULSARS

    SciTech Connect

    Romani, R. W.; Kerr, M.; Craig, H. A.; Johnston, S.; Cognard, I.; Smith, D. A.

    2011-09-01

    Most pulsars observed by the Fermi Large Area Telescope have {gamma}-ray luminosities scaling with spin-down power E-dot as L{sub {gamma}}{approx}(E-dot x 10{sup 33} erg s{sup -1}){sup 1/2}. However, there exist one detection and several upper limits an order of magnitude or more fainter than this trend. We describe these 'sub-luminous' {gamma}-ray pulsars and discuss the case for this being an orientation effect. Of the 12 known young radio pulsars with E-dot >10{sup 34} erg s{sup -1} and d {<=} 2 kpc several are substantially sub-luminous. The limited available geometrical constraints favor aligned geometries for these pulsars, although no one case for alignment is compelling. In this scenario GeV emission detected from such sub-luminous pulsars can be due to a lower altitude, lower-power accelerator gap.

  1. Dosimetry in mixed neutron-gamma fields

    SciTech Connect

    Remec, I.

    1998-04-01

    The gamma field accompanying neutrons may, in certain circumstances, play an important role in the analysis of neutron dosimetry and even in the interpretation of radiation induced steel embrittlement. At the High Flux Isotope Reactor pressure vessel the gamma induced reactions dominate the responses of {sup 237}Np and {sup 238}U dosimeters, and {sup 9}Be helium accumulation fluence monitors. The gamma induced atom displacement rate in steel is higher than corresponding neutron rate, and is the cause of ``accelerated embrittlement`` of HFIR materials. In a large body of water, adjacent to a fission plate, photofissions contribute significantly to the responses of fission monitors and need to be taken into account if the measurements are used for the qualification of the transport codes and cross-section libraries.

  2. (n,{gamma}) Experiments on tin isotopes

    SciTech Connect

    Baramsai, B.; Mitchell, G. E.; Walker, C. L.; Rusev, G.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Mosby, S.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Becvar, F.; Krticka, M.; Kroll, J.; Agvaanluvsan, U.; Dashdorj, D.; Erdenehuluun, B.; Tsend-Ayush, T.

    2013-04-19

    Neutron capture experiments on highly enriched {sup 117,119}Sn isotopes were performed with the DANCE detector array located at the Los Alamos Neutron Science Center. The DANCE detector provides detailed information about the multi-step {gamma}-ray cascade following neutron capture. Analysis of the experimental data provides important information to improve understanding of the neutron capture reaction, including a test of the statistical model, the assignment of spins and parities of neutron resonances, and information concerning the Photon Strength Function (PSF) and Level Density (LD) below the neutron separation energy. Preliminary results for the (n,{gamma}) reaction on {sup 117,119}Sn are presented. Resonance spins of the odd-A tin isotopes were almost completely unknown. Resonance spins and parities have been assigned via analysis of the multi-step {gamma}-ray spectra and directional correlations.

  3. Plasma driven neutron/gamma generator

    DOEpatents

    Leung, Ka-Ngo; Antolak, Arlyn

    2015-03-03

    An apparatus for the generation of neutron/gamma rays is described including a chamber which defines an ion source, said apparatus including an RF antenna positioned outside of or within the chamber. Positioned within the chamber is a target material. One or more sets of confining magnets are also provided to create a cross B magnetic field directly above the target. To generate neutrons/gamma rays, the appropriate source gas is first introduced into the chamber, the RF antenna energized and a plasma formed. A series of high voltage pulses are then applied to the target. A plasma sheath, which serves as an accelerating gap, is formed upon application of the high voltage pulse to the target. Depending upon the selected combination of source gas and target material, either neutrons or gamma rays are generated, which may be used for cargo inspection, and the like.

  4. Tycho's Star Shines in Gamma Rays

    NASA Image and Video Library

    2017-09-27

    NASA image relase December 13, 2011 Gamma-rays detected by Fermi's LAT show that the remnant of Tycho's supernova shines in the highest-energy form of light. This portrait of the shattered star includes gamma rays (magenta), X-rays (yellow, green, and blue), infrared (red) and optical data. Credit: Gamma ray, NASA/DOE/Fermi LAT Collaboration; X-ray, NASA/CXC/SAO; Infrared, NASA/JPL-Caltech; Optical, MPIA, Calar Alto, O. Krause et al. and DSS To read more go to: www.nasa.gov/mission_pages/GLAST/news/tycho-star.html NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  5. Gamma-induced modifications of polycarbonate polymer

    NASA Astrophysics Data System (ADS)

    Sinha, D.; Sahoo, K. L.; Sinha, U. B.; Swu, T.; Chemseddine, A.; Fink, D.

    2004-10-01

    Gamma-induced modifications in polycarbonate polymer have been studied in the dose range of 10(1)-10(6) Gy. Thin films of polycarbonate have been irradiated with different gamma doses from a Co-60 source. To monitor the modifications caused by gamma radiation, FT-IR, differential scanning calorimetry and X-ray diffraction studies have been performed. The studies have indicated that at the dose of 10(6) Gy, phenolic group forms through scissioning of ester linkage. Though the effect of radiation is most significant at the highest dose, the process of modifications starts at 10(3) Gy. Scissioning of the polymeric chain initiates a different morphological zone within the polymer matrix, and the polymer becomes more crystalline with increasing dose. Owing to chain scissioning, the mobility of the polymer increases, which in turn reduces the glass transition temperature of the polymer.

  6. Apparatus and method for detecting gamma radiation

    DOEpatents

    Sigg, R.A.

    1994-12-13

    A high efficiency radiation detector is disclosed for measuring X-ray and gamma radiation from small-volume, low-activity liquid samples with an overall uncertainty better than 0.7% (one sigma SD). The radiation detector includes a hyperpure germanium well detector, a collimator, and a reference source. The well detector monitors gamma radiation emitted by the reference source and a radioactive isotope or isotopes in a sample source. The radiation from the reference source is collimated to avoid attenuation of reference source gamma radiation by the sample. Signals from the well detector are processed and stored, and the stored data is analyzed to determine the radioactive isotope(s) content of the sample. Minor self-attenuation corrections are calculated from chemical composition data. 4 figures.

  7. Apparatus and method for detecting gamma radiation

    DOEpatents

    Sigg, Raymond A.

    1994-01-01

    A high efficiency radiation detector for measuring X-ray and gamma radiation from small-volume, low-activity liquid samples with an overall uncertainty better than 0.7% (one sigma SD). The radiation detector includes a hyperpure germanium well detector, a collimator, and a reference source. The well detector monitors gamma radiation emitted by the reference source and a radioactive isotope or isotopes in a sample source. The radiation from the reference source is collimated to avoid attenuation of reference source gamma radiation by the sample. Signals from the well detector are processed and stored, and the stored data is analyzed to determine the radioactive isotope(s) content of the sample. Minor self-attenuation corrections are calculated from chemical composition data.

  8. Nuclear isomer suitable for gamma ray laser

    NASA Technical Reports Server (NTRS)

    Jha, S.

    1979-01-01

    The operation of gamma ray lasers (gasers) are studied. It is assumed that the nuclear isomers mentioned in previously published papers have inherent limitations. It is further assumed that the judicious use of Bormann effect or the application of the total external reflection of low energy gamma radiation at grazing angle of incidence may permit the use of a gaser crystal sufficiently long to achieve observable stimulated emission. It is suggested that a long lived 0(+) isomer decaying by low energy gamma ray emission to a short lived 2(+) excited nuclear state would be an attractive gaser candidate. It is also suggested that the nuclear isomer be incorporated in a matrix of refractory material having an electrostatic field gradient whose principal axis lies along the length of the medium. This results in the preferential transmission of electric quadrupole radiation along the length of the medium.

  9. Microsecond flares in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.; Cohen, Justin; Teegarden, Bonnard J.; Cline, Thomas L.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Paciesas, William S.; Pendleton, Geoffrey N.; Matteson, James L.

    1993-01-01

    It has been suggested that gamma-ray burst light curves may consist of many superposed flares with a duration shorter than 30/microsec. If true, the implications for the interpretation of burst data are enormous. With the launch of the Compton Gamma-Ray Observatory, four predictions of Mitrofanov's (1989) suggestion can be tested. Our results which contradict this suggestion are (1) the photon arrival times are not correlated between independent detectors, (2) the spectral hardness and intensity does not depend on the detector area, (3) the bursts seen by detectors which measure photon positions do not see microsecond flares, and (4) burst positions deduced from detectors with different projected areas are close to the positions deduced from time-of-flight differences between separated spacecraft. We conclude, therefore, that gamma-ray bursts are not composed of microsecond flares.

  10. Technology Needs for Gamma Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2011-01-01

    Gamma ray astronomy is currently in an exciting period of multiple missions and a wealth of data. Results from INTEGRAL, Fermi, AGILE, Suzaku and Swift are making large contributions to our knowledge of high energy processes in the universe. The advances are due to new detector and imaging technologies. The steps to date have been from scintillators to solid state detectors for sensors and from light buckets to coded aperture masks and pair telescopes for imagers. A key direction for the future is toward focusing telescopes pushing into the hard X-ray regime and Compton telescopes and pair telescopes with fine spatial resolution for medium and high energy gamma rays. These technologies will provide finer imaging of gamma-ray sources. Importantly, they will also enable large steps forward in sensitivity by reducing background.

  11. Gamma rays and neutrons from solar flares

    NASA Astrophysics Data System (ADS)

    Murphy, R. J.

    Recent observations with the Gamma-Ray Spectrometer (GRS) on the Solar Maximum Mission (SMM), along with observations from a number of ground-based and spacecraft detectors, contain a wealth of information on particle acceleration in solar flares. The analysis and interpretation of this data is crucial to the understanding of the flare process. A general analysis of gamma-ray and neutron production in solar flared and a comparison of theoretical calculations with data are presented. An overview of the flare phenomenon is given, recent gamma-ray and particle observations are discussed, the theory of each production process is reviewed and detailed calculations are presented, and a comparison of these calculations with data is made.

  12. Form factors of the transitions {gamma}{sup *}{pi}{sup 0} {r_arrow} {gamma} and {gamma}{sup *}{eta}{r_arrow}{gamma}

    SciTech Connect

    Afanasev, A.

    1994-04-01

    The author discusses possibilities to study {gamma}*{pi}{sup 0} and {gamma}*{eta} {r_arrow} {gamma} transition form factors at CEBAF energies. The author shows that for 4 GeV electron beam, these form factors can be measured at CEBAF for the 4-momentum transfers Q{sup 2} {le} 2.5 (GeV/c){sup 2} using virtual Compton scattering on the proton and nuclear target in the kinematic regime of low momentum transfers to the target. These measurements can be extended to Q{sup 2} {le} 4.0 (GeV/c){sup 2} using the electron beam with the energy 6 GeV.

  13. Scale-invariance in soft gamma repeaters

    NASA Astrophysics Data System (ADS)

    Chang, Zhe; Lin, Hai-Nan; Sang, Yu; Wang, Ping

    2017-06-01

    The statistical properties of the soft gamma repeater SGR J1550-5418 are investigated carefully. We find that the cumulative distributions of fluence, peak flux and duration can be well fitted by a bent power law, while the cumulative distribution of waiting time follows a simple power law. In particular, the probability density functions of fluctuations of fluence, peak flux, and duration have a sharp peak and fat tails, which can be well fitted by a q-Gaussian function. The q values keep approximately steady for different scale intervals, indicating a scale-invariant structure of soft gamma repeaters. Those results support that the origin of soft gamma repeaters is crustquakes of neutron stars with extremely strong magnetic fields. Supported by National Natural Science Foundation of China (11375203, 11675182, 11690022, 11603005), and Fundamental Research Funds for Central Universities (106112016CDJCR301206)

  14. Gamma ray emission from radio pulsars

    NASA Technical Reports Server (NTRS)

    Romani, Roger W.

    1994-01-01

    While the proposed research received partial funding under this grant, during the term of support substantial progress was made on the development of a new model for the emission of gamma-rays from isolated rotation-powered pulsars. In phase one of the work, we showed how a modified version of the 'outer gap' model of pulsar emission could reproduce the double peaked profiles seen in CGRO pulsar observations. This work also demonstrated the spectrum of gap radiation varies significantly with position in the magnetosphere, and produced approximate computations of the emission from outer magnetosphere gap zones, including primary curvature radiation, gamma - gamma pair production and synchrotron radiation and inverse Compton scattering by the resulting secondary particles. This work was followed in phase two by a more complete treatment of the geometry of the radiation zone, and improved connections with observations at other wavelengths.

  15. Gamma-Ray Bursts Search with HAWC

    NASA Astrophysics Data System (ADS)

    de Leon, Cederik; Salazar Ibarguen, Humberto; Villaseã+/-Or Cendejas, Luis Manuel; HAWC Collaboration

    2017-01-01

    The High Altitude Water Cherenkov (HAWC) Gamma-ray observatory is a wide field-of-view observatory sensitive to gamma rays in the 100 GeV - 100 TeV energy range, located in Mexico at an altitude of 4100 m. In the present work we present results on the search for excesses in the rates of signals from the individual photomultiplier tubes (PMTs) using the Time to Digital Converters (TDC) of HAWC. This search is based on the implementation of the Moving Average Ratio Analysis (MARA) focused on the characterization of the different physical phenomena that may give rise to such excesses: noise in the PMTs, atmospheric conditions related with thunderstorms and excesses of astrophysical origin such as variable sources of high energy gamma rays and in particular GRBs. In particular we present an analysis over the HAWC historical data for the search of such excesses and elaborate on the possible physical interpretation of the found excesses.

  16. A novel fully integrated handheld gamma camera

    NASA Astrophysics Data System (ADS)

    Massari, R.; Ucci, A.; Campisi, C.; Scopinaro, F.; Soluri, A.

    2016-10-01

    In this paper, we present an innovative, fully integrated handheld gamma camera, namely designed to gather in the same device the gamma ray detector with the display and the embedded computing system. The low power consumption allows the prototype to be battery operated. To be useful in radioguided surgery, an intraoperative gamma camera must be very easy to handle since it must be moved to find a suitable view. Consequently, we have developed the first prototype of a fully integrated, compact and lightweight gamma camera for radiopharmaceuticals fast imaging. The device can operate without cables across the sterile field, so it may be easily used in the operating theater for radioguided surgery. The prototype proposed consists of a Silicon Photomultiplier (SiPM) array coupled with a proprietary scintillation structure based on CsI(Tl) crystals. To read the SiPM output signals, we have developed a very low power readout electronics and a dedicated analog to digital conversion system. One of the most critical aspects we faced designing the prototype was the low power consumption, which is mandatory to develop a battery operated device. We have applied this detection device in the lymphoscintigraphy technique (sentinel lymph node mapping) comparing the results obtained with those of a commercial gamma camera (Philips SKYLight). The results obtained confirm a rapid response of the device and an adequate spatial resolution for the use in the scintigraphic imaging. This work confirms the feasibility of a small gamma camera with an integrated display. This device is designed for radioguided surgery and small organ imaging, but it could be easily combined into surgical navigation systems.

  17. The Prototype of GAMMA-400 Apparatus

    NASA Astrophysics Data System (ADS)

    Arkhangelskiy, A. I.; Arkhangelskaja, I. V.; Kheymits, M. D.; Runtso, M. F.; Suchkov, S. I.; Topchiev, N. P.; Yurkin, Yu. T.

    Scientific project GAMMA-400 (Gamma-Astronomy Multifunction Modules Apparatus) relates to the new generation of space observatories for investigation of cosmic γ-emission in the energy band from ∼20 MeV up to several TeV, electron/positron fluxes from ∼1 GeV up to ∼10 TeV and cosmic-ray nuclei fluxes with energies up to ∼1015 eV by means of GAMMA-400 gamma-telescope represents the core of the scientific complex. The investigation of gamma ray bursts in the energy band of 10 keV-15 MeV are possible too by means of KONUS-FG apparatus included in the complex. For γ-rays in the energy region from 10 to 100 GeV expected energy resolution changes from ∼3% to ∼1% and angular resolution from ∼0.1% to ∼ 0.01% respectively, γ/protons rejection factor is ∼5·105. The GAMMA-400 satellite will be launched at the beginning of the next decade on the high apogee orbit with following initial parameters: apogee altitude ∼300000 km, perigee altitude ∼500 km, rotation period ∼7 days, inclination to the equator plane 51.4°. The active functioning interval will be 7-10 years. The scientific complex will have next main technical parameters: total weight ∼4100 kg, power consumption ∼2000 W, information quote 100 GByte/day. During the project development, the prototype of apparatus was created for working-off of the main apparatus construction units in laboratory conditions. The main distinctive features of the prototype are presented.

  18. Expression of functional receptors by the human gamma-aminobutyric acid A gamma 2 subunit.

    PubMed

    Martínez-Torres, Ataúlfo; Miledi, Ricardo

    2004-03-02

    gamma-Aminobutyric acid A (GABA(A)) receptors are heteromeric membrane proteins formed mainly by various combinations of alpha, beta, and gamma subunits; and it is commonly thought that the gamma 2 subunit alone does not form functional receptors. In contrast, we found that cDNA encoding the gamma 2L subunit of the human GABA(A) receptor, injected alone into Xenopus oocytes, expressed functional GABA receptors whose properties were investigated by using the two-microelectrode voltage-clamp technique. GABA elicited desensitizing membrane currents that recovered after a few minutes' wash. Repetitive applications of GABA induced a "run-up" of GABA currents that nearly doubled the amplitude of the first response. The GABA currents inverted direction at about -30 mV, indicating that they are carried mainly by Cl(-) ions. The homomeric gamma 2L receptors were also activated by beta-alanine > taurine > glycine, and, like some types of heteromeric GABA(A) receptors, the gamma 2L receptors were blocked by bicuculline and were potentiated by pentobarbital and flunitrazepam. These results indicate that the human gamma 2L subunit is capable of forming fully functional GABA receptors by itself in Xenopus oocytes and suggest that the roles proposed for the various subunits that make up the heteromeric GABA(A) receptors in situ require further clarification.

  19. Separation of electrons and protons in the GAMMA-400 gamma-ray telescope

    NASA Astrophysics Data System (ADS)

    Leonov, A. A.; Galper, A. M.; Bonvicini, V.; Topchiev, N. P.; Adriaini, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Bergstrom, L.; Berti, E.; Bigongiari, G.; Bobkov, S. G.; Boezio, M.; Bogomolov, E. A.; Bonechi, S.; Bongi, M.; Bottai, S.; Castellini, G.; Cattaneo, P. W.; Cumani, P.; Dedenko, G. L.; De Donato, C.; Dogiel, V. A.; 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.; Loginov, V. A.; Longo, F.; Maestro, P.; Marrocchesi, P. S.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu.; Papini, P.; Pearce, M.; Picozza, P.; Rappoldi, A.; Ricciarini, S.; Runtso, M. F.; Ryde, F.; Serdin, O. V.; Sparvoli, R.; Spillantini, P.; Suchkov, S. I.; Taraskin, A. A.; Tavani, M.; Tiberio, A.; Tyurin, E. M.; Ulanov, M. V.; Vacchi, A.; Vannuccini, E.; Vasilyev, G. I.; Yurkin, Yu. T.; Zampa, N.; Zirakashvili, V. N.; Zverev, V. G.

    2015-10-01

    The GAMMA-400 telescope will measure the fluxes of gamma rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. These measurements will allow it to achieve the following scientific objectives: search for signatures of dark matter, investigation of gamma-ray point-like and extended sources, study of the energy spectrum of the Galactic and extragalactic diffuse emission, study of gamma-ray bursts and gamma-ray emission from the active Sun, together with high-precision measurements of the high-energy electrons and positrons spectra, protons and nuclei up to the knee. The bulk of cosmic rays are protons and helium nuclei, whereas the lepton component in the total flux is ∼10-3 at high energy. In the present paper, the simulated capability of the GAMMA-400 telescope to distinguish electrons and positrons from protons in cosmic rays is addressed. The individual contribution to the proton rejection from each detector system of GAMMA-400 is studied separately. The use of the combined information from all detectors allows us to reach a proton rejection of the order of ∼4 × 105 for vertical incident particles and ∼3 × 105 for particles with initial inclination of 30° in the electron energy range from 50 GeV to 1 TeV.

  20. Rescue of gamma2 subunit-deficient mice by transgenic overexpression of the GABAA receptor gamma2S or gamma2L subunit isoforms.

    PubMed

    Baer, K; Essrich, C; Balsiger, S; Wick, M J; Harris, R A; Fritschy, J M; Lüscher, B

    2000-07-01

    The gamma2 subunit is an important functional determinant of GABAA receptors and is essential for formation of high-affinity benzodiazepine binding sites and for synaptic clustering of major GABAA receptor subtypes along with gephyrin. There are two splice variants of the gamma2 subunit, gamma2 short (gamma2S) and gamma2 long (gamma2L), the latter carrying in the cytoplasmic domain an additional eight amino acids with a putative phosphorylation site. Here, we show that transgenic mice expressing either the gamma2S or gamma2L subunit on a gamma2 subunit-deficient background are phenotypically indistinguishable from wild-type. They express nearly normal levels of gamma2 subunit protein and [3H]flumazenil binding sites. Likewise, the distribution, number and size of GABAA receptor clusters colocalized with gephyrin are similar to wild-type in both juvenile and adult mice. Our results indicate that the two gamma2 subunit splice variants can substitute for each other and fulfil the basic functions of GABAA receptors, allowing in vivo studies that address isoform-specific roles in phosphorylation-dependent regulatory mechanisms.

  1. Gamma ray line observations with OSSE

    NASA Technical Reports Server (NTRS)

    Kurfess, J. D.; Grove, J. E.; Johnson, W. N.; Murphy, R. J.; Share, G. H.; Purcell, W. R.; Leising, M. D.; Harris, M. J.

    1997-01-01

    Observations from the oriented scintillation spectrometer experiment of the gamma ray lines originating from a variety of Galactic center sources are reviewed. Extensive observations were acquired of the Galactic center region, including the 0.511 MeV positron annihilation line and associated positronium continuum and Al-26 emission. The results reviewed include: Co-57 from SN 1987A; limits on Co-56 from SN 1991T; gamma ray lines from solar flares; searches for Ti-44 emission from Cas A, and searches for C-12 and O-16 lines from the Orion region.

  2. Gamma ray line observations with OSSE

    NASA Technical Reports Server (NTRS)

    Kurfess, J. D.; Grove, J. E.; Johnson, W. N.; Murphy, R. J.; Share, G. H.; Purcell, W. R.; Leising, M. D.; Harris, M. J.

    1997-01-01

    Observations from the oriented scintillation spectrometer experiment of the gamma ray lines originating from a variety of Galactic center sources are reviewed. Extensive observations were acquired of the Galactic center region, including the 0.511 MeV positron annihilation line and associated positronium continuum and Al-26 emission. The results reviewed include: Co-57 from SN 1987A; limits on Co-56 from SN 1991T; gamma ray lines from solar flares; searches for Ti-44 emission from Cas A, and searches for C-12 and O-16 lines from the Orion region.

  3. VHE Gamma-ray Supernova Remnants

    SciTech Connect

    Funk, Stefan; /KIPAC, Menlo Park

    2007-01-22

    Increasing observational evidence gathered especially in X-rays and {gamma}-rays during the course of the last few years support the notion that Supernova remnants (SNRs) are Galactic particle accelerators up to energies close to the ''knee'' in the energy spectrum of Cosmic rays. This review summarizes the current status of {gamma}-ray observations of SNRs. Shell-type as well as plerionic type SNRs are addressed and prospect for observations of these two source classes with the upcoming GLAST satellite in the energy regime above 100 MeV are given.

  4. Gamma ray inactivation of some animal viruses.

    PubMed Central

    Thomas, F C; Davies, A G; Dulac, G C; Willis, N G; Papp-Vid, G; Girard, A

    1981-01-01

    Twenty samples of animal viruses comprising 14 different viruses in 12 families were subjected to varying doses of gamma irradiation from a 60Co source in a Gamma Cell 220 (Atomic Energy of Canada Limited) to determine lethal dose levels. The dose responses appeared linear throughout inactivation. The D10 values, that is the dose necessary to reduce infectivity by one log10, ranged from less than 0.20 Megarads to approximately 0.55 Megarads. There was not a complete inverse correlation between the target size (virion core) and the D10 value. PMID:6802472

  5. Gamma radiation background measurements from Spacelab 2

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.; Gregory, John C.; Fishman, Gerald J.

    1988-01-01

    A Nuclear Radiation Monitor incorporating a NaI(Tl) scintillation detector was flown as part of the verification flight instrumentation on the Spacelab 2 mission, July 29 to August 6, 1985. Gamma-ray spectra were measured with better than 20 s resolution throughout most of the mission in the energy range 0.1 to 30 MeV. Knowledge of the decay characteristics and the geomagnetic dependence of the counting rates enable measurement of the various components of the Spacelab gamma-ray background: prompt secondary radiation, Earth albedo, and delayed induced radioactivity. The status of the data analysis and present relevant examples of typical background behavior are covered.

  6. Radioactivities and gamma-rays from supernovae

    NASA Technical Reports Server (NTRS)

    Woosley, S. E.

    1991-01-01

    An account is given of the implications of several calculations relevant to the estimation of gamma-ray signals from various explosive astronomical phenomena. After discussing efforts to constrain the amounts of Ni-57 and Ti-44 produced in SN 1987A, attention is given to the production of Al-27 in massive stars and SNs. A 'delayed detonation' model of type Ia SNs is proposed, and the gamma-ray signal which may be expected when a bare white dwarf collapses directly into a neutron star is discussed.

  7. Gamma ray spectrometer for Lunar Scout 2

    NASA Technical Reports Server (NTRS)

    Moss, C. E.; Burt, W. W.; Edwards, B. C.; Martin, R. A.; Nakano, George H.; Reedy, R. C.

    1993-01-01

    We review the current status of the Los Alamos program to develop a high-resolution gamma-ray spectrometer for the Lunar Scout-II mission, which is the second of two Space Exploration Initiative robotic precursor missions to study the Moon. This instrument will measure gamma rays in the energy range of approximately 0.1 - 10 MeV to determine the composition of the lunar surface. The instrument is a high-purity germanium crystal surrounded by an CsI anticoincidence shield and cooled by a split Stirling cycle cryocooler. It will provide the abundance of many elements over the entire lunar surface.

  8. Gamma radiation background measurements from Spacelab 2

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.; Gregory, John C.; Fishman, Gerald J.

    1989-01-01

    A Nuclear Radiation Monitor incorporating a NaI(Tl) scintillation detector was flown as part of the verification flight instrumentation on the Spacelab 2 mission, July 29 to August 6, 1985. Gamma-ray spectra were measured with better than 20 s resolution throughout most of the mission in the energy range 0.1 to 30 MeV. Knowledge of the decay characteristics and the geomagnetic dependence of the counting rates enable measurement of the various components of the Spacelab gamma-ray background: prompt secondary radiation, earth albedo, and delayed induced radioactivity. The status of the data analysis and present relevant examples of typical background behavior are covered.

  9. Geochemical applications for prompt gamma neutron activation

    NASA Astrophysics Data System (ADS)

    Glascock, M. D.; Coveney, R. M.; Tittle, C. W.; Gartner, M. L.; Murphy, R. D.

    1985-05-01

    Neutron-capture (prompt) gamma-ray neutron activation techniques are finding increasing application for both laboratory and in situ measurement of geological materials. Prompt gamma rays can be used to measure abundances for most light mass elements and several heavier mass elements which are more difficult by other techniques. These elements include many of those routinely measured in rocks and minerals. Geochemical abundance data provide information useful for determining rock and ore genesis, porosity, moisture content, salinity, and the detection of formerly oxidizing or reducing environments. Some of the applications include development of petrogenetic models, exploration and development of oil and mineral deposits, and process control in the mining industry.

  10. Environmental monitoring and in situ gamma spectrometry

    NASA Astrophysics Data System (ADS)

    Klusoň, J.

    2001-06-01

    In situ gamma ray spectrometry is widely used for monitoring of natural as well as man-made radionuclides and corresponding gamma fields in the environment or working places. It finds effective application in the operational and accidental monitoring of nuclear facilities and their vicinity, spent fuel storages and waste depositories, radioactive contamination measurements and mapping, environmental, radiohygienic and radiation safety studies, geological prospecting and mapping, etc. Progressive spectrometric methods based on scintillation and semiconductor spectrometry and spectral deconvolution are discussed, including experimental arrangement as well as detection system responses/response matrixes simulation using stochastic (Monte Carlo) models. Methods for ground-level and airborne measurements are presented.

  11. Nuclear Forensics using Gamma-ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Norman, E. B.

    2016-09-01

    Much of George Dracoulis's research career was devoted to utilising gamma-ray spectroscopy in fundamental studies in nuclear physics. This same technology is useful in a wide range of applications in the area of nuclear forensics. Over the last several years, our research group has made use of both high- and low-resolution gamma-ray spectrometers to: identify the first sample of plutonium large enough to be weighed; determine the yield of the Trinity nuclear explosion; measure fission fragment yields as a function of target nucleus and neutron energy; and observe fallout in the U. S. from the Fukushima nuclear reactor accident.

  12. Gamma compensated, self powered neutron detector

    DOEpatents

    Brown, Donald P.

    1977-01-01

    An improved, self-powered, gamma compensated, neutron detector having two electrically conductive concentric cylindrical electrodes and a central rod emitter formed from a material which emits beta particles when bombarded by neutrons. The outer electrode and emitter are maintained at a common potential and the neutron representative current is furnished at the inner cylindrical electrode which serves as a collector. The two concentric cylindrical electrodes are designed to exhibit substantially equal electron emission induced by Compton scattering under neutron bombardment to supply the desired gamma compensation.

  13. The gamma-ray laser project

    NASA Astrophysics Data System (ADS)

    Collins, Carl B.

    1987-07-01

    Recent approaches to the problem of the gamma-ray laser have focused on upconversion techniques in which metastable nuclei are pumped with long wavelength radiation. At the nuclear level the storage of energy can approach tera-Joules (10 to the 12th power J) per liter for thousands of years. However, any plan to use such a resource for a gamma-ray laser poses problems of a broad interdisciplinary nature requiring the fusion of concepts taken from relatively unrelated fields of physics.

  14. Fermi GBM Observations of Terrestrial Gamma Flashes

    NASA Technical Reports Server (NTRS)

    Wilson-Hodge, Colleen A.; Briggs, M. S.; Connaughton, V.; Fishman, G. J.; Bhat, P. N.; Paciesas, W. S.; Preece, R. D.; Kippen, R. M.; vonKienlin, A.; Dwyer, J. R.; Smith, D. M.; Holzworth, R.

    2010-01-01

    In its first two years of operation, the Fermi Gamma Ray Burst Monitor (GBM) has observed 79 Terrestrial Gamma Flashes (TGFs). The thick Bismuth Germanate (BGO) detectors are excellent for TGF spectroscopy, having a high probability of recording the full energy of an incident photon, spanning a broad energy range from 150 keV to 40 MeV, and recording a large number of photons per TGF. Correlations between GBM TGF triggers and lightning sferics detected with the World-Wide Lightning Location Network indicate that TGFs and lightning are simultaneous to within tens of microseconds.

  15. Study of Active Shielding for {gamma} - Spectrometers

    SciTech Connect

    Bikit, I.; Mrdja, D.; Forkapic, S.; Todorovic, N.; Veskovic, M.; Slivka, J.; Conkic, Lj.; Krmar, M.; Varga, E.

    2006-04-26

    The features of the ground located gamma ray spectrometer shielded passively with 12 cm of lead and actively by five 0.5m x 0.5m x 0.05m plastic veto shields are described. The detector mass related background was 0.345 C/kg s. The 511 keV annihilation line was reduced by the factor of 7 by the anticoincidence gate. It is shown that the plastic shields increase the neutron capture gamma line intensities due to neutron thermalization.

  16. Fermi GBM Observations of Terrestrial Gamma Flashes

    NASA Technical Reports Server (NTRS)

    Wilson-Hodge, Colleen A.; Briggs, M. S.; Connaughton, V.; Fishman, G. J.; Bhat, P. N.; Paciesas, W. S.; Preece, R. D.; Kippen, R. M.; vonKienlin, A.; Dwyer, J. R.; hide

    2010-01-01

    In its first two years of operation, the Fermi Gamma Ray Burst Monitor (GBM) has observed 79 Terrestrial Gamma Flashes (TGFs). The thick Bismuth Germanate (BGO) detectors are excellent for TGF spectroscopy, having a high probability of recording the full energy of an incident photon, spanning a broad energy range from 150 keV to 40 MeV, and recording a large number of photons per TGF. Correlations between GBM TGF triggers and lightning sferics detected with the World-Wide Lightning Location Network indicate that TGFs and lightning are simultaneous to within tens of microseconds.

  17. Gamma ray spectroscopy monitoring method and apparatus

    DOEpatents

    Stagg, William R; Policke, Timothy A

    2017-05-16

    The present invention relates generally to the field of gamma ray spectroscopy monitoring and a system for accomplishing same to monitor one or more aspects of various isotope production processes. In one embodiment, the present invention relates to a monitoring system, and method of utilizing same, for monitoring one or more aspects of an isotope production process where the monitoring system comprises: (A) at least one sample cell; (B) at least one measuring port; (C) at least one adjustable collimator device; (D) at least one shutter; and (E) at least one high resolution gamma ray spectrometer.

  18. High Energy Neutron Induced Gamma Production

    SciTech Connect

    Brown, D A; Johnson, M; Navratil, P

    2007-09-28

    N Division has an interest in improving the physics and accuracy of the gamma data it provides to its customers. It was asked to look into major gamma producing reactions for 14 MeV incident neutrons for several low-Z materials and determine whether LLNL's processed data files faithfully represent the current state of experimental and theoretical knowledge for these reactions. To address this, we surveyed the evaluations of the requested materials, made recommendations for the next ENDL release and noted isotopes that will require further experimental study. This process uncovered several major problems in our translation and processing of the ENDF formatted evaluations, most of which have been resolved.

  19. Polarimetric properties of the Reiner Gamma swirl

    NASA Astrophysics Data System (ADS)

    Jeong, Minsup; Kim, Sungsoo S.; Choi, Young-Jun; Garrick-Bethell, Ian

    2016-12-01

    In order to understand the regolith characteristics of the Reiner Gamma swirl, one of the most prominent lunar swirls, we analyze the correlation between the linear polarization flux Q and the intensity I of the swirl. We present comparisons between the phase function (the intensity variation with the phase angle) of the swirl and the phase functions of its neighbors using polarimetric data. We find that the swirl has unusually large Q values for given I values. We also show that the phase function of the swirl is relatively shallow compared to its neighbors. We suggest that the microstructure of the regolith on the Reiner Gamma swirl has been disrupted.

  20. Gamma-sky.net: Portal to the gamma-ray sky

    NASA Astrophysics Data System (ADS)

    Voruganti, Arjun; Deil, Christoph; Donath, Axel; King, Johannes

    2017-01-01

    http://gamma-sky.net is a novel interactive website designed for exploring the gamma-ray sky. The Map View portion of the site is powered by the Aladin Lite sky atlas, providing a scalable survey image tesselated onto a three-dimensional sphere. The map allows for interactive pan and zoom navigation as well as search queries by sky position or object name. The default image overlay shows the gamma-ray sky observed by the Fermi-LAT gamma-ray space telescope. Other survey images (e.g. Planck microwave images in low/high frequency bands, ROSAT X-ray image) are available for comparison with the gamma-ray data. Sources from major gamma-ray source catalogs of interest (Fermi-LAT 2FHL, 3FGL and a TeV source catalog) are overlaid over the sky map as markers. Clicking on a given source shows basic information in a popup, and detailed pages for every source are available via the Catalog View component of the website, including information such as source classification, spectrum and light-curve plots, and literature references. We intend for gamma-sky.net to be applicable for both professional astronomers as well as the general public. The website started in early June 2016 and is being developed as an open-source, open data project on GitHub (https://github.com/gammapy/gamma-sky). We plan to extend it to display more gamma-ray and multi-wavelength data. Feedback and contributions are very welcome!

  1. The measurement of gamma ray induced heating in a mixed neutron and gamma ray environment

    SciTech Connect

    Chiu, H.K.

    1991-10-01

    The problem of measuring the gamma heating in a mixed DT neutron and gamma ray environment was explored. A new detector technique was developed to make this measurement. Gamma heating measurements were made in a low-Z assembly irradiated with 14-Mev neutrons and (n, n{prime}) gammas produced by a Texas Nuclear Model 9400 neutron generator. Heating measurements were made in the mid-line of the lattice using a proportional counter operating in the Continuously-varied Bias-voltage Acquisition mode. The neutron-induced signal was separated from the gamma-induced signal by exploiting the signal rise-time differences inherent to radiations of different linear energy transfer coefficient, which are observable in a proportional counter. The operating limits of this measurement technique were explored by varying the counter position in the low-Z lattice, hence changing the irradiation spectrum observed. The experiment was modelled numerically to help interpret the measured results. The transport of neutrons and gamma rays in the assembly was modelled using the one- dimensional radiation transport code ANISN/PC. The cross-section set used for these calculations was derived from the ENDF/B-V library using the code MC{sup 2}-2 for the case of DT neutrons slowing down in a low-Z material. The calculated neutron and gamma spectra in the slab and the relevant mass-stopping powers were used to construct weighting factors which relate the energy deposition in the counter fill-gas to that in the counter wall and in the surrounding material. The gamma energy deposition at various positions in the lattice is estimated by applying these weighting factors to the measured gamma energy deposition in the counter at those locations.

  2. On Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Ruffini, R.; Bernardini, M. G.; Bianco, C. L.; Caito, L.; Chardonnet, P.; Cherubini, C.; Dainotti, M. G.; Fraschetti, F.; Geralico, A.; Guida, R.; Patricelli, B.; Rotondo, M.; Rueda Hernandez, J. A.; Vereshchagin, G.; Xue, S.-S.

    2008-09-01

    We show by example how the uncoding of Gamma-Ray Bursts (GRBs) offers unprecedented possibilities to foster new knowledge in fundamental physics and in astrophysics. After recalling some of the classic work on vacuum polarization in uniform electric fields by Klein, Sauter, Heisenberg, Euler and Schwinger, we summarize some of the efforts to observe these effects in heavy ions and high energy ion collisions. We then turn to the theory of vacuum polarization around a Kerr-Newman black hole, leading to the extraction of the blackholic energy, to the concept of dyadosphere and dyadotorus, and to the creation of an electron-positron-photon plasma. We then present a new theoretical approach encompassing the physics of neutron stars and heavy nuclei. It is shown that configurations of nuclear matter in bulk with global charge neutrality can exist on macroscopic scales and with electric fields close to the critical value near their surfaces. These configurations may represent an initial condition for the process of gravitational collapse, leading to the creation of an electron-positron-photon plasma: the basic self-accelerating system explaining both the energetics and the high energy Lorentz factor observed in GRBs. We then turn to recall the two basic interpretational paradigms of our GRB model: 1) the Relative Space-Time Transformation (RSTT) paradigm and 2) the Interpretation of the Burst Structure (IBS) paradigm. These paradigms lead to a "canonical" GRB light curve formed from two different components: a Proper-GRB (P-GRB) and an extended afterglow comprising a raising part, a peak, and a decaying tail. When the P-GRB is energetically predominant we have a "genuine" short GRB, while when the afterglow is energetically predominant we have a so-called long GRB or a "fake" short GRB. We compare and contrast the description of the relativistic expansion of the electron-positron plasma within our approach and within the other ones in the current literature. We then turn

  3. Resistance of a gamma/gamma prime - delta directionally solidified eutectic alloy to recrystallization

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Scheuermann, C. M.; Andrews, C. W.

    1975-01-01

    The lamellar directionally solidified nickel-base eutectic alloy gamma/gamma prime-delta has potential as an advanced turbine blade material. The microstructural stability of this alloy was investigated. Specimens were plastically deformed by uniform compression or Brinell indentation, then annealed between 705 and 1120 C. Microstructural changes observed after annealing included gamma prime coarsening, pinch-off and spheroidization of delta lamellae, and the appearance of an unidentified blocky phase in surface layers. All but the first of these was localized in severely deformed regions, suggesting that microstructural instability is not a serious problem in the use of this alloy.

  4. Relativistic feedback models of terrestrial gamma-ray flashes and gamma-ray glows

    NASA Astrophysics Data System (ADS)

    Dwyer, J. R.

    2015-12-01

    Relativistic feedback discharges, also known as dark lightning, are capable of explaining many of the observed properties of terrestrial gamma-ray flashes (TGFs) and gamma-ray glows, both created within thunderstorms. During relativistic feedback discharges, the generation of energetic electrons is self-sustained via the production of backward propagating positrons and back-scattered x-rays, resulting in very larges fluxes of energetic radiation. In addition, ionization produces large electric currents that generate LF/VLF radio emissions and eventually discharge the electric field, terminating the gamma-ray production. In this presentation, new relativistic feedback model results will be presented and compared to recent observations.

  5. Studies in humans using deuterium-labeled alpha- and gamma-tocopherols demonstrate faster plasma gamma-tocopherol disappearance and greater gamma-metabolite production.

    PubMed

    Leonard, Scott W; Paterson, Elaine; Atkinson, Jeffrey K; Ramakrishnan, Rajasekhar; Cross, Carroll E; Traber, Maret G

    2005-04-01

    We hypothesized that human plasma alpha- and gamma-tocopherol concentrations reflect differences in their kinetics, especially influenced by gamma-tocopherol metabolism. Vitamin E kinetics were evaluated in humans (n=14) using approximately 50 mg each of an equimolar ratio of d6-alpha- and d2-gamma-tocopheryl acetates administered orally. Mass spectrometry was used to measure deuterated plasma tocopherols, as well as plasma and urinary vitamin E metabolites, alpha- and gamma-carboxyethylhydroxychromans (CEHCs). Plasma d2-gamma-tocopherol fractional disappearance rates (FDR; 1.39+/-0.44 pools/day, mean+/-SD) were more than three times greater than those of d6-alpha-tocopherol (0.33+/-0.11, p<0.001). The d2-gamma-tocopherol half-life was 13+/-4 h compared with 57+/-19 for d6-alpha-tocopherol. Whereas neither plasma nor urinary d6-alpha-CEHC was detectable (limit of detection 1 nmol/L), gamma-CEHC (labeled plus unlabeled) increased from 129+/-20 to 258+/-40 nmol/L by 12 h and returned to baseline by 48 h; at 12 h d2-gamma-CEHC represented 54+/-4% of plasma gamma-CEHC. Women compared with men had a greater d2-gamma-tocopherol FDR (p<0.004) and a greater maximal plasma d2-gamma-CEHC concentration (p<0.02) and CEHC FDR (p<0.007), as well as excreting four times as much d2-gamma-CEHC (p<0.04) in urine. Thus, gamma-tocopherol is rapidly metabolized to gamma-CEHC, and to a greater degree in women than in men, whereas alpha-tocopherol is maintained in the plasma and little is metabolized to alpha-CEHC.

  6. Found: A Galaxy's Missing Gamma Rays

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-04-01

    Recent reanalysis of data from the Fermi Gamma-ray Space Telescope has resulted in the first detection of high-energy gamma rays emitted from a nearby galaxy. This discovery reveals more about how supernovae interact with their environments.Colliding Supernova RemnantAfter a stellar explosion, the supernovas ejecta expand, eventually encountering the ambient interstellar medium. According to models, this generates a strong shock, and a fraction of the kinetic energy of the ejecta is transferred into cosmic rays high-energy radiation composed primarily of protons and atomic nuclei. Much is still unknown about this process, however. One open question is: what fraction of the supernovas explosion power goes into accelerating these cosmic rays?In theory, one way to answer this is by looking for gamma rays. In a starburst galaxy, the collision of the supernova-accelerated cosmic rays with the dense interstellar medium is predicted to produce high-energy gamma rays. That radiation should then escape the galaxy and be visible to us.Pass 8 to the RescueObservational tests of this model, however, have beenstumped by Arp 220. This nearby ultraluminous infrared galaxy is the product of a galaxy merger ~700 million years ago that fueled a frenzy of starbirth. Due to its dusty interior and extreme levels of star formation, Arp 220 has long been predicted to emit the gamma rays produced by supernova-accelerated cosmic rays. But though weve looked, gamma-ray emission has never been detected from this galaxy until now.In a recent study, a team of scientists led by Fang-Kun Peng (Nanjing University) reprocessed 7.5 years of Fermi observations using the new Pass 8 analysis software. The resulting increase in resolution revealed the first detection of GeV emission from Arp 220!Acceleration EfficiencyGamma-ray luminosity vs. total infrared luminosity for LAT-detected star-forming galaxies and Seyferts. Arp 220s luminosities are consistent with the scaling relation. [Peng et al. 2016

  7. Measurements of the CKM Angle Gamma at BaBar

    SciTech Connect

    Latour, Emmanuel; /Ecole Polytechnique

    2007-10-02

    We present a short review of the measurements of the CKM angle {gamma} performed by the BABAR experiment. We focus on methods using charged B decays, which give a direct access to {gamma} and provide the best constraints so far.

  8. Investigation of gamma rays from the galactic center

    NASA Technical Reports Server (NTRS)

    Helmken, H. F.

    1973-01-01

    Data from Argentine balloon flights made to investigate gamma ray emission from the galactic center are summarized. Data are also summarized from a Palestine, Texas balloon flight to measure gamma rays from NP 0532 and Crab Nebulae.

  9. Study of Z gamma events and limits on anomalous Z Z gamma and Z gamma gamma couplings in p anti-p collisions at s**(1/2) = 1.96-TeV

    SciTech Connect

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Agelou, M.; Agram, J.-L.; Ahn, S.H.; Ahsan, M.; Alexeev, G.D.; Alkhazov, G.; Alton, A.; Alverson, G.; Alves, G.A.; Anastasoaie, M.; Andeen, T.; Anderson, S.; Andrieu, B.; Arnoud, Y.; Askew, A.; /Buenos Aires U. /Rio de Janeiro, CBPF /Rio de Janeiro State U. /Sao Paulo, IFT /Alberta U. /Simon Fraser U. /York U., Canada /McGill U. /Beijing, Inst. High Energy Phys. /Hefei, CUST /Andes U., Bogota /Charles U. /Prague, Tech. U. /Prague, Inst. Phys. /San Francisco de Quito U. /Clermont-Ferrand U. /LPSC, Grenoble /Marseille, CPPM /Orsay, LAL /Paris U., VI-VII /DAPNIA, Saclay

    2005-02-01

    The authors present a measurement of the Z{gamma} production cross section and limits on anomalous ZZ{gamma} and Z{gamma}{gamma} couplings for form-factor scales of {Lambda} = 750 and 1000 GeV. The measurement is based on 138 (152) candidate events in the ee{gamma} ({mu}{mu}{gamma}) final state using 320 (290) pb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV. The 95% C.L. limits on real and imaginary parts of individual anomalous couplings are |h{sub 10,30}{sup Z}| < 0.23, |h{sub 20,40}{sup Z}| < 0.020, |h{sub 10,30}{gamma}| < 0.23, and |h{sub 20,40}{gamma}| < 0.019 for {Lambda} = 1000 GeV.

  10. Regulation of PPAR{gamma} function by TNF-{alpha}

    SciTech Connect

    Ye Jianping

    2008-09-26

    The nuclear receptor PPAR{gamma} is a lipid sensor that regulates lipid metabolism through gene transcription. Inhibition of PPAR{gamma} activity by TNF-{alpha} is involved in pathogenesis of insulin resistance, atherosclerosis, inflammation, and cancer cachexia. PPAR{gamma} activity is regulated by TNF-{alpha} at pre-translational and post-translational levels. Activation of serine kinases including IKK, ERK, JNK, and p38 may be involved in the TNF-regulation of PPAR{gamma}. Of the four kinases, IKK is a dominant signaling molecule in the TNF-regulation of PPAR{gamma}. IKK acts through at least two mechanisms: inhibition of PPAR{gamma} expression and activation of PPAR{gamma} corepressor. In this review article, literature is reviewed with a focus on the mechanisms of PPAR{gamma} inhibition by TNF-{alpha}.

  11. Dietary modulation of peroxisome proliferator-activated receptor gamma.

    PubMed

    Marion-Letellier, R; Déchelotte, P; Iacucci, M; Ghosh, S

    2009-04-01

    Peroxisome proliferator-activated receptor gamma (PPAR gamma) is a nuclear receptor that regulates intestinal inflammation. PPAR gamma is highly expressed in the colon and can be activated by various dietary ligands. A number of fatty acids such as polyunsaturated fatty acids or eicosanoids are considered as endogenous PPAR gamma activators. Nevertheless, other nutrients such as glutamine, spicy food or flavonoids are also able to activate PPAR gamma. As PPAR gamma plays a key role in bacterial induced inflammation, anti-inflammatory properties of probiotics may be mediated through PPAR gamma. The aims of the present review are to discuss of the potential roles of dietary compounds in modulating intestinal inflammation through PPAR gamma.

  12. Anti-Gamma Globulins and Chronic Infection: Comparative Studies of the Immune Response to Various Bacteria and Gamma Globulin Preparations

    PubMed Central

    Williams, Ralph C.; Mellbye, Ove J.; Kronvall, Göran

    1972-01-01

    A study of the relationship of clinical states associated with prolonged infection (bacterial endocarditis and osteomyelitis) and generation of serum anti-gamma globulins was made with particular reference to quantitative amounts of staphylococcal protein A in various infecting strains. No correlation between individual strain amounts of protein A and presence of anti-gamma globulins was detected. Thirty-eight rabbits were immunized intravenously with various strains of bacteria (Staphylococcus aureus, enterococci, Streptomyces viridans, pneumococci, pseudomonas, and Escherichia coli) for periods of 6 weeks, and antibacterial as well as anti-gamma globulin antibodies were assayed. No single group or strain of bacteria stood out as being more prone to produce anti-gamma globulins than others tested. Most rabbits developed anti-gamma globulins reacting with human gamma globulins, whereas the specificity for rabbit gamma globulin appeared more restricted. In 16 rabbits immunized with eight different strains of S. aureus, quantitative elevation of serum gamma globulin above 2.5 g per 100 ml often seemed to be correlated with presence of detectable serum anti-gamma globulins. By contrast 15 rabbits immunized with autologous or isologous rabbit gamma globulins in many instances developed extremely high titers of anti-gamma globulins showing primary specificity for human rather than rabbit gamma globulin. These studies further amplify the remarkably heterogeneous anti-gamma globulin reactivity associated with various types of immune response. PMID:4404684

  13. Gamma ray constraints on the Galactic supernova rate

    NASA Technical Reports Server (NTRS)

    Hartmann, D.; The, L.-S.; Clayton, Donald D.; Leising, M.; Mathews, G.; Woosley, S. E.

    1991-01-01

    We perform Monte Carlo simulations of the expected gamma ray signatures of Galactic supernovae of all types to estimate the significance of the lack of a gamma ray signal due to supernovae occurring during the last millenium. Using recent estimates of the nuclear yields, we determine mean Galactic supernova rates consistent with the historic supernova record and the gamma ray limits. Another objective of these calculations of Galactic supernova histories is their application to surveys of diffuse Galactic gamma ray line emission.

  14. ALEGRO: A new-generation Cherenkov gamma observatory

    NASA Astrophysics Data System (ADS)

    Kholupenko, E. E.; Aruev, P. N.; Baiko, D. A.; Bogdanov, A. A.; Vasilyev, G. I.; Zabrodskii, V. V.; Krasil'shchikov, A. M.; Tuboltsev, Yu. V.; Chichagov, Yu. V.

    2016-12-01

    The concept of a new-generation terrestrial Cherenkov gamma observatory is proposed on the basis of the results of numerical modeling and research and development work. The key parameters of this observatory are estimated. Its primary objective should be the observation of cosmic gamma-ray sources in the 5-50 GeV energy range. Neither ground-based Cherenkov gamma observatories nor orbital gamma telescopes are presently able to perform such observations efficiently.

  15. Applications of Monte Carlo simulations of gamma-ray spectra

    SciTech Connect

    Clark, D.D.

    1995-12-31

    A short, convenient computer program based on the Monte Carlo method that was developed to generate simulated gamma-ray spectra has been found to have useful applications in research and teaching. In research, we use it to predict spectra in neutron activation analysis (NAA), particularly in prompt gamma-ray NAA (PGNAA). In teaching, it is used to illustrate the dependence of detector response functions on the nature of gamma-ray interactions, the incident gamma-ray energy, and detector geometry.

  16. Baseline measurements of terrestrial gamma radioactivity at the CEBAF site

    SciTech Connect

    Wollenberg, H.A.; Smith, A.R.

    1991-10-01

    A survey of the gamma radiation background from terrestrial sources was conducted at the CEBAF site, Newport News, Virginia, on November 12--16, 1990, to provide a gamma radiation baseline for the site prior to the startup of the accelerator. The concentrations and distributions of the natural radioelements in exposed soil were measured, and the results of the measurements were converted into gamma-ray exposure rates. Concurrently, samples were collected for laboratory gamma spectral analyses.

  17. ALEGRO: A new-generation Cherenkov gamma observatory

    SciTech Connect

    Kholupenko, E. E.; Aruev, P. N.; Baiko, D. A.; Bogdanov, A. A.; Vasilyev, G. I.; Zabrodskii, V. V.; Krasil’shchikov, A. M. Tuboltsev, Yu. V.; Chichagov, Yu. V.

    2016-12-15

    The concept of a new-generation terrestrial Cherenkov gamma observatory is proposed on the basis of the results of numerical modeling and research and development work. The key parameters of this observatory are estimated. Its primary objective should be the observation of cosmic gamma-ray sources in the 5–50 GeV energy range. Neither ground-based Cherenkov gamma observatories nor orbital gamma telescopes are presently able to perform such observations efficiently.

  18. Baseline measurements of terrestrial gamma radioactivity at the CEBAF site

    SciTech Connect

    Wollenberg, H.A.; Smith, A.R.

    1991-10-01

    A survey of the gamma radiation background from terrestrial sources was conducted at the CEBAF site, Newport News, Virginia, on November 12--16, 1990, to provide a gamma radiation baseline for the site prior to the startup of the accelerator. The concentrations and distributions of the natural radioelements in exposed soil were measured, and the results of the measurements were converted into gamma-ray exposure rates. Concurrently, samples were collected for laboratory gamma spectral analyses.

  19. Simultaneous optical/gamma-ray observations of GRBs

    NASA Technical Reports Server (NTRS)

    Greiner, J.; Wenzel, W.; Hudec, R.; Moskalenko, E. I.; Metlov, V.; Chernych, N. S.; Getman, V. S.; Ziener, Rainer; Birkle, K.; Bade, N.

    1994-01-01

    Details on the project to search for serendipitous time correlated optical photographic observations of Gamma Ray Bursters (GRB's) are presented. The ongoing photographic observations at nine observatories are used to look for plates which were exposed simultaneously with a gamma ray burst detected by the gamma ray instrument team (BATSE) and contain the burst position. The results for the first two years of the gamma ray instrument team operation are presented.

  20. Gamma-ray astronomy--A status report

    NASA Technical Reports Server (NTRS)

    Holt, Stephen S.

    1994-01-01

    Gamma-rays provide us with powerful insight into the highest energy processes occurring in the cosmos. This review highlights some of the progress in our understanding of gamma-ray astronomy that has been enabled by new data from GRANAT and the Compton Gamma-Ray Observaatory, and suggests requirements for future progress. In particular, the unique role of the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) mission and concurrent multiwavelength observations is highlighted.

  1. Gamma line radiation from supernovae. [nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Arnett, W. D.

    1978-01-01

    Recent calculations of core collapse or massive stars result in explosive ejection of the mantle by a reflected shock. These hydrodynamic results are important for predictions of explosive nucleosynthesis and gamma-ray line emission from supernovae. Previous estimates, based on simple parameterized models or the nucleosynthesis in an average supernova, are compared with these latest results.

  2. Tomographic Gamma Scanner Experience: Three Cases

    SciTech Connect

    Mercer, David J.

    2014-06-30

    This is a summary of field applications of tomographic gamma scanning (TGS). Three cases are shown: enriched uranium scanning at Rocky Flats, heat-source plutonium at LANL, and plutonium-bearing pyrochemical salts at Rocky Flats. Materials are taken from the references shown below.

  3. Polymerase Gamma Disease through the Ages

    ERIC Educational Resources Information Center

    Saneto, Russell P.; Naviaux, Robert K.

    2010-01-01

    The most common group of mitochondrial disease is due to mutations within the mitochondrial DNA polymerase, polymerase gamma 1 ("POLG"). This gene product is responsible for replication and repair of the small mitochondrial DNA genome. The structure-function relationship of this gene product produces a wide variety of diseases that at times, seems…

  4. Gamma-ray Astrophysics with AGILE

    SciTech Connect

    Longo, Francesco |; Tavani, M.; Barbiellini, G.; Argan, A.; Basset, M.; Boffelli, F.; Bulgarelli, A.; Caraveo, P.; Cattaneo, P.; Chen, A.; Costa, E.; Del Monte, E.; Di Cocco, G.; Di Persio, G.; Donnarumma, I.; Feroci, M.; Fiorini, M.; Foggetta, L.; Froysland, T.; Frutti, M.

    2007-07-12

    AGILE will explore the gamma-ray Universe with a very innovative instrument combining for the first time a gamma-ray imager and a hard X-ray imager. AGILE will be operational in spring 2007 and it will provide crucial data for the study of Active Galactic Nuclei, Gamma-Ray Bursts, unidentified gamma-ray sources. Galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing. The AGILE instrument is designed to simultaneously detect and image photons in the 30 MeV - 50 GeV and 15 - 45 keV energy bands with excellent imaging and timing capabilities, and a large field of view covering {approx} 1/5 of the entire sky at energies above 30 MeV. A CsI calorimeter is capable of GRB triggering in the energy band 0.3-50 MeV AGILE is now (March 2007) undergoing launcher integration and testing. The PLSV launch is planned in spring 2007. AGILE is then foreseen to be fully operational during the summer of 2007.

  5. Gamma Radiation Tolerance of Magnetic Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Ren, Fanghui; Jander, Albrecht; Dhagat, Pallavi; Nordman, Cathy

    2011-10-01

    Determining the radiation tolerance of magnetic tunnel junctions (MTJ), which are the storage elements of non-volatile magnetoresistive random access memories (MRAM), is important for investigating their potential application in space. In this effort, the effect of gamma radiation on MTJs with MgO tunnel barriers was studied. Experimental and control groups of samples were characterized by ex situ measurements of the magnetoresistive hysteresis loops and I-V curves. The experimental group was exposed to gamma rays from a ^60Co source. The samples initially received a dose of 5.9 Mrad (Si) after which they were again characterized electrically and magnetically. Irradiation was then continued for a cumulative dose of 10 Mrad and the devices re-measured. The result shows no change in magnetic properties such as coercivity or exchange coupling due to irradiation. After correcting for differences in temperature at the time of testing, the tunneling magnetoresistance was also found to be unchanged. Thus, it has been determined that MgO-based MTJs are highly tolerant of gamma radiation, particularly in comparison to silicon field-effect transistors which have been shown to degrade with gamma ray exposure even as low as 100 Krad [Zhiyuan Hu. et al., IEEE trans. on Nucl. Sci., vol. 58, 2011].

  6. Gamma-Ray Telescope and Uncertainty Principle

    ERIC Educational Resources Information Center

    Shivalingaswamy, T.; Kagali, B. A.

    2012-01-01

    Heisenberg's Uncertainty Principle is one of the important basic principles of quantum mechanics. In most of the books on quantum mechanics, this uncertainty principle is generally illustrated with the help of a gamma ray microscope, wherein neither the image formation criterion nor the lens properties are taken into account. Thus a better…

  7. Polymerase Gamma Disease through the Ages

    ERIC Educational Resources Information Center

    Saneto, Russell P.; Naviaux, Robert K.

    2010-01-01

    The most common group of mitochondrial disease is due to mutations within the mitochondrial DNA polymerase, polymerase gamma 1 ("POLG"). This gene product is responsible for replication and repair of the small mitochondrial DNA genome. The structure-function relationship of this gene product produces a wide variety of diseases that at times, seems…

  8. [Analog gamma camera digitalization computer system].

    PubMed

    Rojas, G M; Quintana, J C; Jer, J; Astudillo, S; Arenas, L; Araya, H

    2004-01-01

    Digitalization of analogue gamma cameras systems, using special acquisition boards in microcomputers and appropriate software for acquisition and processing of nuclear medicine images is described in detail. Microcomputer integrated systems interconnected by means of a Local Area Network (LAN) and connected to several gamma cameras have been implemented using specialized acquisition boards. The PIP software (Portable Image Processing) was installed on each microcomputer to acquire and preprocess the nuclear medicine images. A specialized image processing software has been designed and developed for these purposes. This software allows processing of each nuclear medicine exam, in a semiautomatic procedure, and recording of the results on radiological films. . A stable, flexible and inexpensive system which makes it possible to digitize, visualize, process, and print nuclear medicine images obtained from analogue gamma cameras was implemented in the Nuclear Medicine Division. Such a system yields higher quality images than those obtained with analogue cameras while keeping operating costs considerably lower (filming: 24.6%, fixing 48.2% and developing 26%.) Analogue gamma camera systems can be digitalized economically. This system makes it possible to obtain optimal clinical quality nuclear medicine images, to increase the acquisition and processing efficiency, and to reduce the steps involved in each exam.

  9. New shield for gamma-ray spectrometry

    NASA Technical Reports Server (NTRS)

    Brar, S. S.; Gustafson, P. F.; Nelson, D. M.

    1969-01-01

    Gamma-ray shield that can be evacuated, refilled with a clean gas, and pressurized for exclusion of airborne radioactive contaminants effectively lowers background noise. Under working conditions, repeated evacuation and filling procedures have not adversely affected the sensitivity and resolution of the crystal detector.

  10. HAWC observatory catches first gamma rays

    NASA Astrophysics Data System (ADS)

    Frías Villegas, Gabriela

    2013-06-01

    The world's largest and most modern gamma-ray observatory has carried out its first successful observations. Located inside the Pico de Orizaba national park in the Mexican state of Puebla, the High-Altitude Water Cherenkov Observatory (HAWC) is a collaboration between 26 Mexican and US institutions.

  11. Multiple gamma lines from semi-annihilation

    NASA Astrophysics Data System (ADS)

    D'Eramo, Francesco; McCullough, Matthew; Thaler, Jesse

    2013-04-01

    Hints in the Fermi data for a 130 GeV gamma line from the galactic center have ignited interest in potential gamma line signatures of dark matter. Explanations of this line based on dark matter annihilation face a parametric tension since they often rely on large enhancements of loop-suppressed cross sections. In this paper, we pursue an alternative possibility that dark matter gamma lines could arise from ''semi-annihilation'' among multiple dark sector states. The semi-annihilation reaction ψiψj → ψkγ with a single final state photon is typically enhanced relative to ordinary annihilation ψibar psii → γγ into photon pairs. Semi-annihilation allows for a wide range of dark matter masses compared to the fixed mass value required by annihilation, opening the possibility to explain potential dark matter signatures at higher energies. The most striking prediction of semi-annihilation is the presence of multiple gamma lines, with as many as order N3 lines possible for N dark sector states, allowing for dark sector spectroscopy. A smoking gun signature arises in the simplest case of degenerate dark matter, where a strong semi-annihilation line at 130 GeV would be accompanied by a weaker annihilation line at 173 GeV. As a proof of principle, we construct two explicit models of dark matter semi-annihilation, one based on non-Abelian vector dark matter and the other based on retrofitting Rayleigh dark matter.

  12. Cascade model of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Sturrock, P. A.; Harding, A. K.; Daugherty, J. K.

    1989-01-01

    If, in a neutron star magnetosphere, an electron is accelerated to an energy of 10 to the 11th or 12th power eV by an electric field parallel to the magnetic field, motion of the electron along the curved field line leads to a cascade of gamma rays and electron-positron pairs. This process is believed to occur in radio pulsars and gamma ray burst sources. Results are presented from numerical simulations of the radiation and photon annihilation pair production processes, using a computer code previously developed for the study of radio pulsars. A range of values of initial energy of a primary electron was considered along with initial injection position, and magnetic dipole moment of the neutron star. The resulting spectra was found to exhibit complex forms that are typically power law over a substantial range of photon energy, and typically include a dip in the spectrum near the electron gyro-frequency at the injection point. The results of a number of models are compared with data for the 5 Mar., 1979 gamma ray burst. A good fit was found to the gamma ray part of the spectrum, including the equivalent width of the annihilation line.

  13. Slow gamma takes the reins in replay.

    PubMed

    Colgin, Laura Lee

    2012-08-23

    The mechanisms supporting hippocampal memory reactivation are puzzling. Reactivation occurs during ripple oscillations, yet ripples are not coordinated across regions. In this issue of Neuron, Carr et al. (2012) report that another oscillation, slow gamma, coordinates memory reactivation across the hippocampal network.

  14. INTEGRAL: International Gamma Ray Astrophysics Laboratory

    NASA Astrophysics Data System (ADS)

    Winkler, Christoph

    1992-07-01

    INTEGRAL is dedicated to the fine spectroscopy and imaging of celestial gamma ray sources in the energy range 15 keV to 10 MeV. The instruments on INTEGRAL will achieve a gamma ray line sensitivity of 3 times 10 to the minus 6th power ph/sq cm/s, a continuum sensitivity of 3 times 10 to the minus 8th power ph/sq cm/s/keV at 1 MeV (approximately 10 mCrab at 1 MeV) and imaging with an angular resolution of better than 20 minutes. This represents an order of magnitude improvement over the Gamma Ray Observatory (GRO) in line sensitivity, energy resolution and angular resolution. Comparison with the low energy gamma ray telescope Sigma also shows a major advance: the continuum sensitivity improvement is considerably more than one order of magnitude between 100 keV and 1 MeV; and the narrow line sensitivity is increased by nearly two orders of magnitude. INTEGRAL consists of two main instruments: a germanium spectrometer and a caesium iodide coded aperture mask imager. These instruments are supplemented by two monitors: an X-ray monitor and an optical transient camera.

  15. COMPUTER ANALYSIS OF PLANAR GAMMA CAMERA IMAGES

    EPA Science Inventory



    COMPUTER ANALYSIS OF PLANAR GAMMA CAMERA IMAGES

    T Martonen1 and J Schroeter2

    1Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. EPA, Research Triangle Park, NC 27711 USA and 2Curriculum in Toxicology, Unive...

  16. Inspection of cargo containers using gamma radiation

    NASA Astrophysics Data System (ADS)

    Hussein, Esam M. A.; Gokhale, Prasad; Arendtsz, Nina V.; Lawrence, Andre H.

    1997-02-01

    This paper investigate, with the aid of Monte Carlo simulations and laboratory experiments, a technique for the detection of narcotics in large cargo containers using gamma-radiation. The transmission and back-scattering of photons, at different energies, is used to provide information useful for identifying the presence of bulk quantities of commonly encountered narcotics.

  17. Toward standardising gamma camera quality control procedures

    NASA Astrophysics Data System (ADS)

    Alkhorayef, M. A.; Alnaaimi, M. A.; Alduaij, M. A.; Mohamed, M. O.; Ibahim, S. Y.; Alkandari, F. A.; Bradley, D. A.

    2015-11-01

    Attaining high standards of efficiency and reliability in the practice of nuclear medicine requires appropriate quality control (QC) programs. For instance, the regular evaluation and comparison of extrinsic and intrinsic flood-field uniformity enables the quick correction of many gamma camera problems. Whereas QC tests for uniformity are usually performed by exposing the gamma camera crystal to a uniform flux of gamma radiation from a source of known activity, such protocols can vary significantly. Thus, there is a need for optimization and standardization, in part to allow direct comparison between gamma cameras from different vendors. In the present study, intrinsic uniformity was examined as a function of source distance, source activity, source volume and number of counts. The extrinsic uniformity and spatial resolution were also examined. Proper standard QC procedures need to be implemented because of the continual development of nuclear medicine imaging technology and the rapid expansion and increasing complexity of hybrid imaging system data. The present work seeks to promote a set of standard testing procedures to contribute to the delivery of safe and effective nuclear medicine services.

  18. 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.

  19. Gamma ray observations of the solar system

    SciTech Connect

    Not Available

    1981-01-01

    Two general categories are discussed concerning the evolution of the solar system: the dualistic view, the planetesimal approach and the monistic view, the nebular hypothesis. The major points of each view are given and the models that are developed from these views are described. Possible applications of gamma ray astronomical observations to the question of the dynamic evolution of the solar system are discussed.

  20. Gamma-ray Emission from Globular Clusters

    NASA Astrophysics Data System (ADS)

    Tam, Pak-Hin T.; Hui, Chung Y.; Kong, Albert K. H.

    2016-03-01

    Over the last few years, the data obtained using the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope has provided new insights on high-energy processes in globular clusters, particularly those involving compact objects such as MilliSecond Pulsars (MSPs). Gamma-ray emission in the 100 MeV to 10 GeV range has been detected from more than a dozen globular clusters in our galaxy, including 47 Tucanae and Terzan 5. Based on a sample of known gammaray globular clusters, the empirical relations between gamma-ray luminosity and properties of globular clusters such as their stellar encounter rate, metallicity, and possible optical and infrared photon energy densities, have been derived. The measured gamma-ray spectra are generally described by a power law with a cut-off at a few gigaelectronvolts. Together with the detection of pulsed γ-rays from two MSPs in two different globular clusters, such spectral signature lends support to the hypothesis that γ-rays from globular clusters represent collective curvature emission from magnetospheres of MSPs in the clusters. Alternative models, involving Inverse-Compton (IC) emission of relativistic electrons that are accelerated close to MSPs or pulsar wind nebula shocks, have also been suggested. Observations at >100 GeV by using Fermi/LAT and atmospheric Cherenkov telescopes such as H.E.S.S.-II, MAGIC-II, VERITAS, and CTA will help to settle some questions unanswered by current data.

  1. Gamma ray observations of the solar system

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Two general categories are discussed concerning the evolution of the solar system: the dualistic view, the planetesimal approach; and the monistic view, the nebular hypothesis. The major points of each view are given and the models that are developed from these views are described. Possible applications of gamma ray astronomical observations to the question of the dynamic evolution of the solar system are discussed.

  2. Diffuse Galactic Soft Gamma-Ray Emission

    NASA Astrophysics Data System (ADS)

    Boggs, S. E.; Lin, R. P.; Slassi-Sennou, S.; Coburn, W.; Pelling, R. M.

    2000-11-01

    The Galactic diffuse soft gamma-ray (30-800 keV) emission has been measured from the Galactic center by the High Resolution Gamma-Ray and Hard X-Ray Spectrometer balloon-borne germanium instrument to determine the spectral characteristics and origin of the emission. The resulting Galactic diffuse continuum is found to agree well with a single power law (plus positronium) over the entire energy range, consistent with RXTE and COMPTEL/Compton Gamma Ray Observatory observations at lower and higher energies, respectively. We find no evidence of spectral steepening below 200 keV, as has been reported in previous observations. The spatial distribution along the Galactic ridge is found to be nearly flat, with upper limits set on the longitudinal gradient and with no evidence of an edge in the observed region. The soft gamma-ray diffuse spectrum is well modeled by inverse Compton scattering of interstellar radiation off of cosmic-ray electrons, minimizing the need to invoke inefficient nonthermal bremsstrahlung emission. The resulting power requirement is well within that provided by Galactic supernovae. We speculate that the measured spectrum provides the first direct constraints on the cosmic-ray electron spectrum below 300 MeV.

  3. {gamma}5 Higgs coupling and supersymmetry breaking

    SciTech Connect

    Moreno, Matias; Bernal-Arroyo, Jorge

    1996-02-20

    It is pointed out that the spontaneous symmetry breaking occurring from a {gamma}5-coupling contains a generalization of supersymmetry. Consequences for the fermion mass spectra are studied for three models: a generic one, the pion-nucleon or quark-pion chiral system and a modified electroweak model.

  4. Concomitant GRID boost for Gamma Knife radiosurgery

    SciTech Connect

    Ma Lijun; Kwok, Young; Chin, Lawrence S.; Simard, J. Marc; Regine, William F.

    2005-11-15

    We developed an integrated GRID boost technique for Gamma Knife radiosurgery. The technique generates an array of high dose spots within the target volume via a grid of 4-mm shots. These high dose areas were placed over a conventional Gamma Knife plan where a peripheral dose covers the full target volume. The beam weights of the 4-mm shots were optimized iteratively to maximize the integral dose inside the target volume. To investigate the target volume coverage and the dose to the adjacent normal brain tissue for the technique, we compared the GRID boosted treatment plans with conventional Gamma Knife treatment plans using physical and biological indices such as dose-volume histogram (DVH), DVH-derived indices, equivalent uniform dose (EUD), tumor control probabilities (TCP), and normal tissue complication probabilities (NTCP). We found significant increase in the target volume indices such as mean dose (5%-34%; average 14%), TCP (4%-45%; average 21%), and EUD (2%-22%; average 11%) for the GRID boost technique. No significant change in the peripheral dose coverage for the target volume was found per RTOG protocol. In addition, the EUD and the NTCP for the normal brain adjacent to the target (i.e., the near region) were decreased for the GRID boost technique. In conclusion, we demonstrated a new technique for Gamma Knife radiosurgery that can escalate the dose to the target while sparing the adjacent normal brain tissue.

  5. The [Gamma] Algorithm and Some Applications

    ERIC Educational Resources Information Center

    Castillo, Enrique; Jubete, Francisco

    2004-01-01

    In this paper the power of the [gamma] algorithm for obtaining the dual of a given cone and some of its multiple applications is discussed. The meaning of each sequential tableau appearing during the process is interpreted. It is shown that each tableau contains the generators of the dual cone of a given cone and that the algorithm updates the…

  6. In sync: gamma oscillations and emotional memory

    PubMed Central

    Headley, Drew B.; Paré, Denis

    2013-01-01

    Emotional experiences leave vivid memories that can last a lifetime. The emotional facilitation of memory has been attributed to the engagement of diffusely projecting neuromodulatory systems that enhance the consolidation of synaptic plasticity in regions activated by the experience. This process requires the propagation of signals between brain regions, and for those signals to induce long-lasting synaptic plasticity. Both of these demands are met by gamma oscillations, which reflect synchronous population activity on a fast timescale (35–120 Hz). Regions known to participate in the formation of emotional memories, such as the basolateral amygdala, also promote gamma-band activation throughout cortical and subcortical circuits. Recent studies have demonstrated that gamma oscillations are enhanced during emotional situations, coherent between regions engaged by salient stimuli, and predict subsequent memory for cues associated with aversive stimuli. Furthermore, neutral stimuli that come to predict emotional events develop enhanced gamma oscillations, reflecting altered processing in the brain, which may underpin how past emotional experiences color future learning and memory. PMID:24319416

  7. Gamma-ray Pulsars: Models and Predictions

    NASA Technical Reports Server (NTRS)

    Harding Alice K.; White, Nicholas E. (Technical Monitor)

    2000-01-01

    Pulsed emission from gamma-ray pulsars originates inside the magnetosphere, from radiation by charged particles accelerated near the magnetic poles or in the outer gaps. In polar cap models, the high energy spectrum is cut off by magnetic pair production above an energy that is, dependent on the local magnetic field strength. While most young pulsars with surface fields in the range B = 10(exp 12) - 10(exp 13) G are expected to have high energy cutoffs around several GeV, the gamma-ray spectra of old pulsars having lower surface fields may extend to 50 GeV. Although the gamma-ray emission of older pulsars is weaker, detecting pulsed emission at high energies from nearby sources would be an important confirmation of polar cap models. Outer gap models predict more gradual high-energy turnovers of the primary curvature emission around 10 GeV, but also predict an inverse Compton component extending to TeV energies. Detection of pulsed TeV emission, which would not survive attenuation at the polar caps, is thus an important test of outer gap models. Next-generation gamma-ray telescopes sensitive to GeV-TeV emission will provide critical tests of pulsar acceleration and emission mechanisms.

  8. Physics issues of gamma ray burst emissions

    NASA Technical Reports Server (NTRS)

    Liang, Edison

    1987-01-01

    The critical physics issues in the interpretation of gamma-ray-burst spectra are reviewed. An attempt is made to define the emission-region parameter space satisfying the maximum number of observational and theoretical constraints. Also discussed are the physical mechanisms responsible for the bursts that are most consistent with the above parameter space.

  9. IUS guidance algorithm gamma guide assessment

    NASA Technical Reports Server (NTRS)

    Bray, R. E.; Dauro, V. A.

    1980-01-01

    The Gamma Guidance Algorithm which controls the inertial upper stage is described. The results of an independent assessment of the algorithm's performance in satisfying the NASA missions' targeting objectives are presented. The results of a launch window analysis for a Galileo mission, and suggested improvements are included.

  10. Spectroscopic mode identification in gamma Doradus stars

    NASA Astrophysics Data System (ADS)

    Rylvia Pollard, Karen

    2015-08-01

    The MUSICIAN programme at the University of Canterbury has been successfully identifying frequencies and pulsation modes in many gamma Doradus stars using hundreds of precise, high resolution spectroscopic observations. This paper describes some of these frequency and mode identifications and the emerging patterns of the programme.

  11. Structural organization of mouse peroxisome proliferator-activated receptor {gamma} (mPPAR{gamma}) gene: Alternative promoter use and different splicing yield two mPPAR{gamma} isoforms

    SciTech Connect

    Zhu, Y.; Qi, C.; Rao, M.S.

    1995-08-15

    To gain insight into the regulation of expression of peroxisome proliferator-activated receptor (PPAR) isoforms, we have determined the structural organization of the mouse PPAR {gamma} (mPPAR{gamma}) gene. This gene extends >105 kb and gives rise to two mRNAs (mPPAR{gamma}1 and mPPAR{gamma}2) that differ at their 5{prime} ends. The mPPAR{gamma}2 cDNA encodes an additional 30 amino acids N-terminal to the first ATG codon of mPPAR{gamma}1 and reveals a different 5{prime} untranslated sequence. We show that mPPAR{gamma}1 mRNA is encoded by eight exons, whereas the mPPAR{gamma}2 mRNA is encoded by seven exons. Most of the 5{prime} untranslated sequence of mPPAR{gamma}1 mRNA is encoded by two exons, whereas the 5{prime} untranslated sequence of mPPAR{gamma}1 mRNA is encoded by two exons, whereas the 5{prime} untranslated sequence and the extra 30 N-terminal amino acids of mPPAR{gamma}2 are encoded by one exon, which is located between the second and third exons coding for mPPAR{gamma}1. The last six exons of mPPAR{gamma} gene code for identical sequences in mPPAR{gamma}1 and mPPAR{gamma}2 isoforms. The mPPAR{gamma}1 and mPPAR{gamma}2 isoforms are transcribed from different promoters. The mPPAR{gamma} gene has been mapped to chromosome 6 E3-F1 by in situ hybridization using a biotin-labeled probe. These results establish that at least one of the PPAR genes yields more than one protein product, similar to that encountered with retinoid X receptor and retinoic acid receptor genes. The existence of multiple PPAR isoforms transcribed from different promoters could increase in the diversity of ligand and tissue-specific transcriptional responses. 22 refs., 5 figs.

  12. Interdiffusion Behavior of Pt-Diffused gamma+gamma' Coatings on Ni-Based Superalloys

    SciTech Connect

    Zhang, Ying; Stacy, J P; Pint, Bruce A; Haynes, James A; Hazel, Brian T; Nagaraj, Ben

    2008-01-01

    Platinum-diffused {gamma} + {gamma}{prime} coatings ({approx} 20 at.% Al, {approx} 22 at.% Pt) were synthesized on Rene 142 and Rene N5 Ni-based superalloys by electroplating the substrates with {approx} 7 {micro}m of Pt, followed by an annealing treatment in vacuum at 1175 C. In order to study the compositional and microstructural evolution of these coatings at elevated temperatures, interdiffusion experiments were carried out on coated specimens in the temperature range of 900-1050 C for various durations. Composition profiles of the alloying elements in the {gamma} + {gamma}{prime} coatings before and after diffusion experiments were determined by electron probe microanalysis. Although the change of the Al content in the coatings was minimal under these interdiffusion conditions, the decrease of the Pt content and increase of the diffusion depth of Pt into the substrate alloys were significant. A preliminary diffusion model was used to estimate the Pt penetration depth after diffusion.

  13. Measurement of the {sup 157}Gd(n,{gamma}) reaction with the DANCE {gamma} calorimeter array

    SciTech Connect

    Chyzh, A.; Dashdorj, D.; Baramsai, B.; Mitchell, G. E.; Walker, C. L.; Becker, J. A.; Parker, W.; Wu, C. Y.; Becvar, F.; Kroll, J.; Krticka, M.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.

    2011-07-15

    The {sup 157}Gd(n,{gamma}) reaction was measured with the DANCE {gamma} calorimeter (consisting of 160 BaF{sub 2} scintillation detectors) at the Los Alamos Neutron Science Center. The multiplicity distributions of the {gamma} decay were used to determine the resonance spins up to E{sub n}=300 eV. The {gamma}-ray energy spectra for different multiplicities were measured for the s-wave resonances. The shapes of these spectra were compared with simulations based on the use of the DICEBOX statistical model code. Simulations showed that the scissors mode is required not only for the ground-state transitions but also for transitions between excited states.

  14. Structure and creep rupture properties of directionally solidified eutectic gamma/gamma-prime-alpha alloy

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.; Wirth, G.

    1982-01-01

    A simple ternary gamma/gamma-prime-alpha alloy of nominal composition (wt-%) Ni-32Mo-6Al has been directionally solidified at 17 mm/h and tested in creep rupture at 1073, 1173, and 1273 K. A uniform microstructure consisting of square-shaped Mo fibers in a gamma + gamma-prime matrix was found despite some variation in the molybdenum and aluminum concentrations along the growth direction. Although the steady-state creep rate is well described by the normal stress temperature equation, the stress exponent (12) and the activation energy (580 kJ/mol) are high. The rupture behavior is best characterized by the Larson-Miller parameter where the constant equals 20.

  15. Gamma ray lines from the Galactic Center and gamma ray transients

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Leiter, D.; Lingenfelter, R. E.

    1981-01-01

    The observations and interpretations of cosmic (nonsolar) gamma ray lines are discussed. The most prominent of these lines is the e(+)e(-) annihilation line which was observed from the Galactic Center and from several gamma ray transients. At the Galactic Center the e(+)e(-) pairs are probably produced by an accreting massive black hole (solar mass of approximately one million) and annihilate within the central light year to produce a line at almost exactly 0.511 MeV. In gamma ray transients the annihilation line is redshifted by factors consistent with neutron star surface redshifts. Other observed transient gamma ray lines appear to be due to cyclotron absorption in the strong magnetic fields of neutron stars, and nuclear deexcitations and neutron capture, which could also occur on or around these objects.

  16. Studying the High Energy Gamma Ray Sky with Gamma Ray Large Area Space Telescope (GLAST)

    NASA Technical Reports Server (NTRS)

    Kamae, T.; Ohsugi, T.; Thompson, D. J.; Watanabe, K.

    1998-01-01

    Building on the success of the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory, the Gamma Ray Large Area Space Telescope (GLAST) will make a major step in the study of such subjects as blazars, gamma Ray bursts, the search for dark matter, supernova remnants, pulsars, diffuse radiation, and unidentified high energy sources. The instrument will be built on new and mature detector technologies such as silicon strip detectors, low-power low-noise LSI, and a multilevel data acquisition system. GLAST is in the research and development phase, and one full tower (of 25 total) is now being built in collaborating institutes. The prototype tower will be tested thoroughly at Stanford Linear Accelerator Center (SLAC) in the fall of 1999.

  17. Measuring the charged pion polarizability in the gamma gamma -> pi+pi- reaction

    SciTech Connect

    Lawrence, David W.; Miskimen, Rory A.; Mushkarenkov, Alexander Nikolaevich; Smith, Elton S.

    2013-08-01

    Development has begun of a new experiment to measure the charged pion polarizability $\\alpha_{\\pi}-\\beta_{\\pi}$. The charged pion polarizability ranks among the most important tests of low-energy QCD presently unresolved by experiment. Analogous to precision measurements of $\\pi^{\\circ}\\rightarrow\\gamma\\gamma$ that test the intrinsic odd-parity (anomalous) sector of QCD, the pion polarizability tests the intrinsic even-parity sector of QCD. The measurement will be performed using the $\\gamma\\gamma\\rightarrow\\pi^{+{}}\\pi^{-{}}$ cross section accessed via the Primakoff mechanism on nuclear targets using the GlueX detector in Hall D at Jefferson Lab. The linearly polarized photon source in Hall-D will be utilized to separate the Primakoff cross-section from coherent $\\rho^{\\circ}$ production.

  18. Cross Sections for (gamma)-ray Production in the 191Ir (n,xn(gamma)) Reactions

    SciTech Connect

    Fotiades, N; Nelson, R O; Devlin, M; Chadwick, M B; Talou, P; Becker, J A; Garrett, P E; Younes, W

    2005-01-11

    Discrete {gamma}-ray spectra have been measured for nuclei populated in {sup 191}Ir(n{sub 4}xn{gamma}) with x{<=}11, as a function of incident neutron energy using neutrons from the 'white' neutron source at the Los Alamos Neutron Science Center's WNR facility. The energy of the neutrons was determined using the time-of-flight technique. The data were taken using the GEANIE spectrometer. The cross sections for emission of 202 {gamma} rays of {sup 181-191}Ir were determined for neutron energies 0.2 MeV < E{sub n} < 300 MeV. Comparison with model calculations, using the GNASH reaction model, and with GEANIE results from the similar {sup 193}Ir(n{sub 4}xn{gamma}) reactions is made.

  19. Structure and creep rupture properties of directionally solidified eutectic gamma/gamma-prime-alpha alloy

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.; Wirth, G.

    1982-01-01

    A simple ternary gamma/gamma-prime-alpha alloy of nominal composition (wt-%) Ni-32Mo-6Al has been directionally solidified at 17 mm/h and tested in creep rupture at 1073, 1173, and 1273 K. A uniform microstructure consisting of square-shaped Mo fibers in a gamma + gamma-prime matrix was found despite some variation in the molybdenum and aluminum concentrations along the growth direction. Although the steady-state creep rate is well described by the normal stress temperature equation, the stress exponent (12) and the activation energy (580 kJ/mol) are high. The rupture behavior is best characterized by the Larson-Miller parameter where the constant equals 20.

  20. Very High-Energy Gamma-Ray Sources.

    ERIC Educational Resources Information Center

    Weekes, Trevor C.

    1986-01-01

    Discusses topics related to high-energy, gamma-ray astronomy (including cosmic radiation, gamma-ray detectors, high-energy gamma-ray sources, and others). Also considers motivation for the development of this field, the principal results to date, and future prospects. (JN)

  1. Future Prospects for Space-Based Gamma Ray Astronomy

    NASA Astrophysics Data System (ADS)

    McConnell, Mark

    2016-03-01

    The gamma-ray sky offers a unique view into broad range of high energy astrophysical phenomena, from nearby solar flares, to galactic pulsars, to gamma-ray bursts at the furthest reaches of the Universe. In recent years, results from the Fermi mission have further demonstrated the broad range of topics that can be addressed by gamma-ray observations. The full range of gamma-ray energies is quite broad, from about 100 keV up to about 100 TeV. The energy range below several hundred GeV is the domain of space-based gamma-ray observatories, a range that is not completely covered by the Fermi LAT instrument. The gamma ray community has embarked on an effort to define the next steps for space-based gamma ray astronomy. These discussions are being facilitated through the Gamma-ray Science Interest Group (GammaSIG), which exists to provide community input to NASA in regards to current and future needs of the gamma-ray astrophysics community. Through a series of workshops and symposia, the GammaSIG is working to bring the community together with one common vision, a vision that will be expressed in the form of a community roadmap. This talk will summarize some of the latest results from active gamma ray observatories and will summarize the status of the community roadmap effort.

  2. Gamma radiation from blazar PKS 0537-441

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

    1993-01-01

    The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) observed high-energy gamma rays from PKS 0537-441 during observations in 1991 July-August. Upper limits from later EGRET observations suggest time variability.

  3. Environmental gamma radiation measurements on the island of Pantelleria.

    PubMed

    Brai, M; Bellia, S; Di Liberto, R; Dongarra, G; Hauser, S; Parello, F; Puccio, P; Rizzo, S

    1992-09-01

    The population exposure to those living on the island of Pantelleria, Italy, was estimated by measuring the natural gamma background. Gamma spectra of natural rocks and measurements of absorbed dose in air were taken. A correlation was found between the mean gamma exposure rate and the mean values of natural radionuclide concentrations in the investigated rocks.

  4. Atypical Laterality of Resting Gamma Oscillations in Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Maxwell, Christina R.; Villalobos, Michele E.; Schultz, Robert T.; Herpertz-Dahlmann, Beate; Konrad, Kerstin; Kohls, Gregor

    2015-01-01

    Abnormal brain oscillatory activity has been found in autism spectrum disorders (ASD) and proposed as a potential biomarker. While several studies have investigated gamma oscillations in ASD, none have examined resting gamma power across multiple brain regions. This study investigated resting gamma power using EEG in 15 boys with ASD and 18 age…

  5. Gamma-Ray Telescopes: 400 Years of Astronomical Telescopes

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Cannizzo, John K.

    2010-01-01

    The last half-century has seen dramatic developments in gamma-ray telescopes, from their initial conception and development through to their blossoming into full maturity as a potent research tool in astronomy. Gamma-ray telescopes are leading research in diverse areas such as gamma-ray bursts, blazars, Galactic transients, and the Galactic distribution of Al-26.

  6. Atypical Laterality of Resting Gamma Oscillations in Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Maxwell, Christina R.; Villalobos, Michele E.; Schultz, Robert T.; Herpertz-Dahlmann, Beate; Konrad, Kerstin; Kohls, Gregor

    2015-01-01

    Abnormal brain oscillatory activity has been found in autism spectrum disorders (ASD) and proposed as a potential biomarker. While several studies have investigated gamma oscillations in ASD, none have examined resting gamma power across multiple brain regions. This study investigated resting gamma power using EEG in 15 boys with ASD and 18 age…

  7. Gamma radiation from blazar PKS 0537-441

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

    1993-01-01

    The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) observed high-energy gamma rays from PKS 0537-441 during observations in 1991 July-August. Upper limits from later EGRET observations suggest time variability.

  8. 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 where...

  9. 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 where...

  10. 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 where...

  11. Very High-Energy Gamma-Ray Sources.

    ERIC Educational Resources Information Center

    Weekes, Trevor C.

    1986-01-01

    Discusses topics related to high-energy, gamma-ray astronomy (including cosmic radiation, gamma-ray detectors, high-energy gamma-ray sources, and others). Also considers motivation for the development of this field, the principal results to date, and future prospects. (JN)

  12. The development of gamma-gamma-prime lamellar structures in a nickel-base superalloy during elevated temperature mechanical testing

    NASA Technical Reports Server (NTRS)

    Mackay, R. A.; Ebert, L. J.

    1985-01-01

    The kinetics of the formation and subsequent development of the directional coarsening of the gamma-prime precipitate in model Ni-Al-Mo-Ta superalloy single crystals are examined during tensile creep under various stress levels at 982 and 1038 C. Special attention is given to the gamma and gamma-prime relation to creep time and strain in order to trace the changing gamma-gamma-prime morphology. Directional coarsening of gamma-prime is found to begin during primary creep and its rate is shown to increase with an increase in temperature or stress level. The length of gamma-prime thickness increased linearly with time up to a plateau reached after the onset of steady state creep. The raft thickness, equal to the gamma-prime size, remained constant at this initial value up through the onset of the tertiary creep. The interlaminar spacing indicates the stability of directionally coarsened structure.

  13. TEM, HRTEM, electron holography and electron tomography studies of gamma' and gamma'' nanoparticles in Inconel 718 superalloy.

    PubMed

    Dubiel, B; Kruk, A; Stepniowska, E; Cempura, G; Geiger, D; Formanek, P; Hernandez, J; Midgley, P; Czyrska-Filemonowicz, A

    2009-11-01

    The aim of the study was the identification of gamma' and gamma'' strengthening precipitates in a commercial nickel-base superalloy Inconel 718 (Ni-19Fe-18Cr-5Nb-3Mo-1Ti-0.5Al-0.04C, wt %) using TEM dark-field, HRTEM, electron holography and electron tomography imaging. To identify gamma' and gamma'' nanoparticles unambiguously, a systematic analysis of experimental and theoretical diffraction patterns were performed. Using HRTEM method it was possible to analyse small areas of precipitates appearance. Electron holography and electron tomography techniques show new possibilities of visualization of gamma' and gamma'' nanoparticles. The analysis by means of different complementary TEM methods showed that gamma'' particles exhibit a shape of thin plates, while gamma' phase precipitates are almost spherical.

  14. The development of gamma-gamma-prime lamellar structures in a nickel-base superalloy during elevated temperature mechanical testing

    NASA Technical Reports Server (NTRS)

    Mackay, R. A.; Ebert, L. J.

    1985-01-01

    The kinetics of the formation and subsequent development of the directional coarsening of the gamma-prime precipitate in model Ni-Al-Mo-Ta superalloy single crystals are examined during tensile creep under various stress levels at 982 and 1038 C. Special attention is given to the gamma and gamma-prime relation to creep time and strain in order to trace the changing gamma-gamma-prime morphology. Directional coarsening of gamma-prime is found to begin during primary creep and its rate is shown to increase with an increase in temperature or stress level. The length of gamma-prime thickness increased linearly with time up to a plateau reached after the onset of steady state creep. The raft thickness, equal to the gamma-prime size, remained constant at this initial value up through the onset of the tertiary creep. The interlaminar spacing indicates the stability of directionally coarsened structure.

  15. Diagnosing ICF gamma-ray physics

    SciTech Connect

    Herrmann, Hans W; Kim, Y H; Mc Evoy, A; Young, C S; Mack, J M; Hoffman, N; Wilson, D C; Langenbrunner, J R; Evans, S; Sedillo, T; Batha, S H; Dauffy, L; Stoeffl, W; Malone, R; Kaufman, M I; Cox, B C; Tunnel, T W; Miller, E K; Rubery, M

    2010-01-01

    Gamma rays produced in an ICF environment open up a host of physics opportunities we are just beginning to explore. A branch of the DT fusion reaction, with a branching ratio on the order of 2e-5 {gamma}/n, produces 16.7 MeV {gamma}-rays. These {gamma}-rays provide a direct measure of fusion reaction rate (unlike x-rays) without being compromised by Doppler spreading (unlike neutrons). Reaction-rate history measurements, such as nuclear bang time and burn width, are fundamental quantities that will be used to optimize ignition on the National Ignition Facility (NIF). Gas Cherenkov Detectors (GCD) that convert fusion {gamma}-rays to UV/visible Cherenkov photons for collection by fast optical recording systems established their usefulness in illuminating ICF physics in several experimental campaigns at OMEGA. Demonstrated absolute timing calibrations allow bang time measurements with accuracy better than 30 ps. System impulse response better than 95 ps fwhm have been made possible by the combination of low temporal dispersion GCDs, ultra-fast microchannel-plate photomultiplier tubes (PMT), and high-bandwidth Mach Zehnder fiber optic data links and digitizers, resulting in burn width measurement accuracy better than 10ps. Inherent variable energy-thresholding capability allows use of GCDs as {gamma}-ray spectrometers to explore other interesting nuclear processes. Recent measurements of the 4.44 MeV {sup 12}C(n,n{prime}) {gamma}-rays produced as 14.1 MeV DT fusion neutrons pass through plastic capsules is paving the way for a new CH ablator areal density measurement. Insertion of various neutron target materials near target chamber center (TCC) producing secondary, neutron-induced {gamma}y-rays are being used to study other nuclear interactions and as in-situ sources to calibrate detector response and DT branching ratio. NIF Gamma Reaction History (GRH) diagnostics, based on the GCD concept, are now being developed based on optimization of sensitivity, bandwidth

  16. Gamma ray spectroscopy in astrophysics: Solar gamma ray astronomy on solar maximum mission. [experimental design

    NASA Technical Reports Server (NTRS)

    Forrest, D. J.

    1978-01-01

    The SMM gamma ray experiment and the important scientific capabilities of the instrument are discussed. The flare size detectable as a function of spectrum integration time was studied. A preliminary estimate indicates that a solar gamma ray line at 4.4 MeV one-fifth the intensity of that believed to have been emitted on 4 August 1972 can be detected in approximately 1000 sec with a confidence level of 99%.

  17. GAMMA FACILITY, TRA641. AERIAL CONTEXTUAL VIEW OF GAMMA FACILITY, UNDER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    GAMMA FACILITY, TRA-641. AERIAL CONTEXTUAL VIEW OF GAMMA FACILITY, UNDER CONSTRUCTION NEXT TO CONTROL HOUSE, TRA-620. CAMERA FACING NORTHWEST. CONCRETE SLAB AND BUILDING AT RIGHT EDGE OF VIEW IS TRA-614, IN USE AS A COLD METALLURGICAL LAB. INL NEGATIVE NO. 13187. Unknown Photographer, 11/24/1954 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  18. Gamma ray bursts of black hole universe

    NASA Astrophysics Data System (ADS)

    Zhang, T. X.

    2015-07-01

    Slightly modifying the standard big bang theory, Zhang recently developed a new cosmological model called black hole universe, which has only a single postulate but is consistent with Mach's principle, governed by Einstein's general theory of relativity, and able to explain existing observations of the universe. In the previous studies, we have explained the origin, structure, evolution, expansion, cosmic microwave background radiation, quasar, and acceleration of black hole universe, which grew from a star-like black hole with several solar masses through a supermassive black hole with billions of solar masses to the present state with hundred billion-trillions of solar masses by accreting ambient matter and merging with other black holes. This study investigates gamma ray bursts of black hole universe and provides an alternative explanation for the energy and spectrum measurements of gamma ray bursts according to the black hole universe model. The results indicate that gamma ray bursts can be understood as emissions of dynamic star-like black holes. A black hole, when it accretes its star or merges with another black hole, becomes dynamic. A dynamic black hole has a broken event horizon and thus cannot hold the inside hot (or high-frequency) blackbody radiation, which flows or leaks out and produces a GRB. A star when it collapses into its core black hole produces a long GRB and releases the gravitational potential energy of the star as gamma rays. A black hole that merges with another black hole produces a short GRB and releases a part of their blackbody radiation as gamma rays. The amount of energy obtained from the emissions of dynamic star-like black holes are consistent with the measurements of energy from GRBs. The GRB energy spectra derived from this new emission mechanism are also consistent with the measurements.

  19. Gamma-Guided Stereotactic Breast Biopsy System

    SciTech Connect

    B. Welch, R. Brem, B. Kross, V. Popov, R. Wojcik, S. Majewski

    2006-10-01

    A gamma-ray imaging system has been developed for acquiring stereo images of the distribution of radiopharmaceuticals in breast tissue. The system consists of a small field-of-view gamma-ray camera mounted to a stereotactic biopsy table. The camera is mounted on a rotational arm such that it can be used to image the breast from two 15deg stereo views. These stereo images can be used to determine the three dimensional spatial location of a region of focal uptake. Once the location of this region is determined, this information can be used as a guide for stereotactic core needle biopsy. The accuracy that the spatial location of a source can be determined was investigated by moving a point source within the field of view. A center-of gravity calculation was used to localize the centroid of the image of the source and this was used to determine the spatial location. Measurements indicate that the source can be localized to within 1 mm. A comparison of the operation of the gamma imaging system and an x-ray imaging system has been done using a dual modality phantom. These measurements indicated that the spatial location of an isolated source can be determined by the gamma imaging system to within approximately the same performance criteria as required for the X-ray system (1 mm). Collimators were tested to determine the spatial resolution in the transverse dimension and the impact of this transverse resolution on the axial resolution was investigated. The performance of this gamma-guided stereotactic biopsy system will be presented.

  20. The effect of alloying on gamma and gamma prime in nickel-base superalloys

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.; Wallace, J. F.

    1972-01-01

    An investigation was conducted to determine the compositional limits of gamma and gamma prime phases in nickel-base superalloys. Fifty-one nickel-base alloys were melted under vacuum and heat treated for 4 hours at 1190 C followed by 1008 hours at 850 C. The alloys had the following composition ranges: A1 4.0 to 13 atomic percent, Cr 6.5 to 20.5 percent, Ti 0.25 to 4.75 percent, Mo 0.0 to 6.0 percent, and W 0.0 to 4.0 percent. The residues from the ammonium sulfate electrolytic extraction for the two-phase alloys were analyzed chemically and by X-ray diffraction. The results of the investigation were used to assemble a mathematical model of the gamma-gamma prime region of the Ni-Al-Cr-Ti-Mo-W system. A computer program was written to analyze the model of the phase diagram. Some of these results are also presented graphically. The resulting model is capable of satisfactorily predicting the compositions of conjugate gamma-gamma prime phases in the alloys investigated and twelve of fifteen commercial superalloys studied.