The Neutron Radiation Detection Instrument-1A (NeRDI-1A) is a neutron sensor on the International Space Station (ISS) as part of the Department of Defense Space Test Program (STP) mission STP-H9. NeRDI-1A uses the scintillator Tl2LiYCl6:Ce as well as three Domino microstructured semiconductor neutron detectors (MSNDs) with varying levels of moderation and an EJ-270 plastic scintillator. The primary objective of NeRDI-1A is to space qualify TLYC and MSND detectors by studying the effects of on-orbit radiation background on the performance of these detectors over the nominal one-year mission. NeRDI-1A was launched to the ISS on 15 March 2023 GMT aboard SpX-27.
The GAGG Radiation Instruments (GARI), two identical instruments, are designed to space-qualify new gamma-ray detector technology for space-based astrophysical and defense applications. The detector technology offers improved energy resolution, lower power consumption and reduced size compared to similar systems. Each identical GARI instrument consists of a two cerium-doped gadolinium aluminum gallium garnet (GAGG (Gd3(Al,Ga)5O12 :Ce)) scintillation detectors. The crystals have an energy resolution of 4.2% at 662 keV (specified by the manufacturer) compared to the 6.5% of traditional sodium iodide, and the material has found widespread use in medical imaging applications. GAGG is also unique in the fact that it is rugged (resistant to harsh environments) and one of the few non-hygroscopic scintillators available. GARI’s objective is to study the on-orbit internal activation of the GAGG material and measure the performance of the silicon photomultiplier (SiPM) readouts over its 1-year mission. The combined detectors measure the gamma-ray spectrum over the energy range of 0.02 - 8 MeV. The GARI mission payoff is a space-qualified compact, high-sensitivity gamma-ray spectrometer with improved energy resolution relative to previous sensors. Applicable studies in solar physics and astrophysics include solar flares, Gamma Ray Bursts, novae, supernovae, and the synthesis of the elements. Department of Defense (DoD) and security applications are also possible. Construction of the GARI instruments has been completed, and both instruments are being integrated onto their respective platforms. Both instruments are expected to launch in December of 2021 onboard STP-H7 and STP-H8. This work discusses the objectives, design details and mission concept of operations of the GARI spectrometers.
Strontium iodide doped with europium [SrI2(Eu2+)] is a new scintillator material being developed as an alternative to lanthanum bromide doped with cerium [LaBr3(Ce3+)] for use in high-energy astrophysical detectors. As with all scintillators, the issue of nonproportionality is important because it affects the energy resolution of the detector. We investigate how the nonproportionality of SrI2(Eu2+) changes as a function of temperature from 16 to 60°C by heating the SrI2(Eu2+) scintillator separate from the photomultiplier tube. In a separate experiment, we also investigate the nonproportionality at high energies (up to 6 MeV) of SrI2(Eu2+) at a testing facility located at NASA Goddard Space Flight Center. We find that the nonproportionality increases nearly monotonically as the temperature of the SrI2(Eu2+) scintillator is increased, although there is evidence of nonmonotonic behavior near 40°C, perhaps due to electric charge carriers trapping in the material. We also find that within the energy range of 662 keV to 6.1 MeV, the change in the nonproportionality of SrI2(Eu2+) is ∼1.5 to 2%.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.