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  1. Radiation Damage and Mitigation by Minority Carrier Injection in InAsSb/AlAsSb Heterojunction Barrier Mid-Wave Infrared Detector

    Peale, Robert E. ; Fredricksen, C. J. ; Klem, John F. - Journal of Electronic Materials
    Here, the effects of gamma and proton irradiation, and of forward bias minority carrier injection, on photo-response were investigated for InAsSb/AlAsSb pBn mid-wave infrared (MWIR) detectors with an engineered majority-carrier barrier. Room-temperature gamma irradiation had an insignificant effect on 77 K photo-response. Gamma irradiation at 77 K detector temperature, however, decreased in situ photo-response by 19% after a cumulative dose of ~ 500 krad(Si). Subsequent forward bias minority carrier injection had no effect on photo-response. The 77 K detectors irradiated with 30 MeV protons up to 2 Mrad(Si) had photo-response degraded by up to 70%, but here forward bias minoritymore » carrier (hole) injection caused up to 12% recovery that persisted more than 30 min. These results suggest a mitigation strategy for maintaining the photo-response of similar detectors in radiation environments that cause displacement damage defects.« less

  2. Monte Carlo simulations demonstrating physics of equivalency of gamma, electron-beam, and X-ray for radiation sterilization

    Kroc, Thomas K. - Radiation Physics and Chemistry (1993)
    We report the sterilization of medical devices using the gamma rays from the decay of cobalt-60 has accumulated decades of experience of the performance of the materials and devices that are irradiated. The use of radiation using electron beams and x-rays has much less experience and this leads to questions of equivalency between these three technologies. Computer simulations were conducted to model the relevant physical processes of the interactions of each of the three forms of radiation in order to compare the spectra of electron energies at energies below 500 keV. It is predominantly the electrons below this threshold thatmore » produce the sterilization dose. No difference in energy spectra was seen between the three types of initial radiation. It is concluded that there is no energy dependent difference between gamma, e-beam, and x-ray for radiation sterilization.« less

  3. Relaxation of compressive stress in gamma-irradiated Viton™ fluoroelastomer

    Gourdin, William H. ; Jensen, Wayne - Fusion Engineering and Design

  4. LIGO/Virgo Black Holes from a First Order Quark Confinement Phase Transition

    Davoudiasl, Hooman - Physical Review Letters

  5. Effects of thermal aging and ionizing radiation on sPVC and aromatic polyether urethane used to store nuclear materials

    Dumont, Joseph Henry ; Murphy, Eamonn Conor ; Geller, Drew Adam ; ... - Polymer Testing
    In this work, we tested the degradation of two polymeric materials under conditions routinely encountered in nuclear applications. Polymers in the form of plastic bags are commonly used along with metal containers to store and transport nuclear materials. The role of the bag, also known as bag-out bag, is to prevent contamination in case the metal containers are breached. Polymeric materials of interest are sPVC and aromatic polyether urethane (APU-ether), which in this study were exposed to alpha, gamma and thermal conditions. These conditions were specifically chosen to simulate the harsh environments normally encountered in the storage of nuclear materials.more » The physical, chemical and mechanical properties of these materials were investigated by a series of characterization methods before and after exposures. Our results highlight the superior stability of APU-ether under thermal aging and ionizing radiation and provide new insights into the durability of polymeric materials used in nuclear applications. In conclusion, these findings will serve as the foundation for a rational selection of new bag-out bag materials to be considered in the nuclear industry.« less

  6. Variation of α from a dark matter force

    Davoudiasl, Hooman ; Giardino, Pier Paolo - Physics Letters B

  7. GeV-scale messengers of Planck-scale dark matter

    Davoudiasl, Hooman ; Mohlabeng, Gopolang - Physical Review D

  8. Electroweak corrections to Higgs boson decays to γ γ and W + W − in standard model EFT

    Dawson, S. ; Giardino, P. P. - Physical Review D

  9. High-Z Sensitized Plastic Scintillators: A Review

    Hajagos, Tibor Jacob ; Liu, Chao ; Cherepy, Nerine J. ; ... - Advanced Materials
    The need for affordable and reliable radiation detectors has prompted significant investment in new radiation detector materials, due to concerns about national security and nuclear nonproliferation. Plastic scintillators provide an affordable approach to large volume detectors, yet their performance for high-energy gamma radiation is severely limited by the small radiation stopping power inherent to their low atomic number. Although some sensitization attempts with organometallics were made in the 1950s to 1960s, the concomitant decrease in light yield has limited the usefulness of these sensitized detectors. Recently, with new knowledge gained during the rapid development of organic optoelectronics and nanotechnology, theremore » has been a revived interest in the field of heavy element sensitized plastic scintillators. In this paper, the recent efforts on sensitized plastic scintillators are summarized. Basic scintillator physics is first reviewed. The discussion then focuses on two major thrusts in the field: sensitization with: (1) organometallics and (2) oxide and fluoride nanoparticles. The design rationales and major results are examined in detail, with existing limitations and possible future pathways discussed. Lastly, special attention is paid to the underlying energy deposition and transfer processes, as these determine the key performance metrics such as light yield and radioluminescence decay lifetime.« less

  10. Correlated fission data measurements with DANCE and NEUANCE

    Jandel, Marian ; Baramsai, Baramsai ; Bredeweg, Todd Allen ; ... - Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
    To enhance the capabilities of the DANCE array, a new detector array NEUANCE was developed to enable simultaneous measurements of prompt fission neutrons and γ rays. NEUANCE was designed and constructed using 21 stilbene organic scintillator crystals. It was installed in the central cavity of the DANCE array. Signals from the 160 BaF2 detectors of DANCE and the 21 detectors of NEUANCE were merged into a newly designed high-density high-throughput data acquisition system. The excellent pulse shape discrimination properties of stilbene enabled detection of neutrons with energy thresholds as low as 30–40 keVee. A fission reaction tagging method was developedmore » using a NEUANCE γ-ray or neutron signal. The probability of detecting a neutron from the spontaneous fission of 252Cf using NEUANCE is 47%. New correlated data for prompt fission neutrons and prompt fission rays were obtained for 252Cf using this high detection efficiency experimental setup. In conclusion, average properties of prompt fission neutron emission as a function of prompt fission γ-ray quantities were also obtained, suggesting that neutron and γ-ray emission in fission are correlated.« less
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