The Strontium Iodide Radiation Instrumentation (SIRI) is designed to space-qualify new gamma-ray detector technology for space-based astrophysical and defense applications. This new technology offers improved energy resolution, lower power consumption and reduced size compared to similar systems. The SIRI instrument consists of a single europiumdoped strontium iodide (SrI<sub>2</sub>:Eu) scintillation detector. The crystal has an energy resolution of 3% at 662 keV compared to the 6.5% of traditional sodium iodide and was developed for terrestrial-based weapons of mass destruction (WMD) detection. SIRI’s objective is to study the internal activation of the SrI<sub>2</sub>:Eu material and measure the performance of the silicon photomultiplier (SiPM) readouts over a 1-year mission. The combined detector and readout measure the gammaray spectrum over the energy range of 0.04 - 4 MeV. The SIRI mission payoff is a space-qualified compact, highsensitivity gamma-ray spectrometer with improved energy resolution relative to previous sensors. Scientific applications 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 SIRI instrument has been completed, and it is currently awaiting integration onto the spacecraft. The expected launch date is May 2018 onboard STPSat-5. This work discusses the objectives, design details and the STPSat-5 mission concept of operations of the SIRI spectrometer.
We have developed, fabricated and tested a prototype imaging neutron spectrometer designed for real-time neutron
source location and identification. Real-time detection and identification is important for locating materials. These
materials, specifically uranium and transuranics, emit neutrons via spontaneous or induced fission. Unlike other forms
of radiation (e.g. gamma rays), penetrating neutron emission is very uncommon. The instrument detects these neutrons,
constructs images of the emission pattern, and reports the neutron spectrum. The device will be useful for security and
proliferation deterrence, as well as for nuclear waste characterization and monitoring. The instrument is optimized for
imaging and spectroscopy in the 1-20 MeV range. The detection principle is based upon multiple elastic neutron-proton
scatters in organic scintillator. Two detector panel layers are utilized. By measuring the recoil proton and scattered
neutron locations and energies, the direction and energy spectrum of the incident neutrons can be determined and
discrete and extended sources identified. Event reconstruction yields an image of the source and its location. The
hardware is low power, low mass, and rugged. Its modular design allows the user to combine multiple units for increased
sensitivity. We will report the results of laboratory testing of the instrument, including exposure to a calibrated Cf-252
source. Instrument parameters include energy and angular resolution, gamma rejection, minimum source identification
distances and times, and projected effective area for a fully populated instrument.
SONNE, the SOlar NeutroN Experiment proposed for Solar Probe Plus, is designed to measure solar neutrons from 1-20 MeV and solar gammas from 0.5-10 MeV. SONNE is a double scatter instrument that employs imaging to maximize its signal-to-noise ratio by rejecting neutral particles from non-solar directions. Under the assumption of quiescent or episodic small-flare activity, one can constrain the energy content and power dissipation by fast ions in the low corona.
Although the spectrum of protons and ions produced by nanoflaring activity is unknown, we estimate the signal in neutrons and γ−rays that would be present within thirty solar radii, constrained by earlier measurements at 1 AU. Laboratory results and simulations will be presented illustrating the instrument sensitivity and resolving power.
FNIT (the Fast Neutron Imaging Telescope), a detector with both imaging and energy measurement capabilities,
sensitive to neutrons in the range 0.8-20 MeV, was initially conceived to study solar neutrons as a candidate design for
the Inner Heliosphere Sentinel (IHS) spacecraft of NASA's Solar Sentinels program and successively reconfigured to
locate fission neutron sources. By accurately identifying the position of the source with imaging techniques and
reconstructing the Watt spectrum of fission neutrons, FNIT can detect samples of special nuclear material (SNM),
including heavily shielded and masked ones. The detection principle is based on multiple elastic neutron-proton
scatterings in organic scintillators. By reconstructing n-p event locations and sequence and measuring the recoil proton
energies, the direction and energy spectrum of the primary neutron flux can be determined and neutron sources
identified. We describe the design of the FNIT prototype and present its energy reconstruction and imaging
performance, assessed by exposing FNIT to a neutron beam and to a Pu fission neutron source.