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Hoover, Andrew Scott

Publications and source records attributed to Hoover, Andrew Scott.

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Proton Quenching in Rare-Earth Inorganic Scintillators: GAGG:Ce and YSO:Ce

Scintillator detectors are an integral component of radiation detection systems for a variety of applications such as medical imaging, accelerator diagnostics, and space science. Typically, a scintillator detector’s response is characterized using gamma sources to understand the detection response to different types of radiation, including charged particle detection. However, there exists a nonlinearity of the amount of light produced from an incident gamma ray of specific energy and the light produced from an incident charged particle of the same energy. This important effect, known as quenching, must be accounted for to interpret energies from charged particles incident on detectors. In this article, we present results of quenching parameterization for two types of cerium-doped inorganic scintillators, Y2SiO5:Ce (YSO:Ce) and Gd3Al2Ga3O12:Ce (GAGG:Ce). We measured the light output from incident proton energies from 1 to 25 MeV using a 3-MV tandem accelerator and two reactions: Au(p,p)Au and 3He(d,p)⁴He. Using gamma-ray sources to calibrate the detectors, we compared the measured electron-equivalent energy versus the incident energy expected. Using an adaptation of the Birks semi-empirical formula, we extracted the Birks parameter (kB) to understand quenching. For one of the GAGG:Ce samples, the kB parameter of 0.0072 [g cm-2 MeV-1] is comparable to a similar study where the value of kB was 0.0065 [g cm-2 MeV-1]. For YSO:Ce, no other kB values were found in the literature. Three different types of GAGG:Ce were used to collect measurements of kB as a function of dopant concentration.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Gamma and Decay Energy Spectroscopy Measurements of Trinitite

We report gamma-ray spectroscopy measurements of trinitite samples and analogous samples obtained from detonation sites in Nevada and Semipalatinsk, as well as in situ measurements of topsoil at the Trinity site. We also report the first isotopic composition measurements of trinitite using the novel forensics technique of decay energy spectroscopy (DES) as a complement to traditional forensics techniques. Our gamma spectroscopy and DES measurements are compared to other published results.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

The Mini Astrophysical MeV Background Observatory (MAMBO): A CubeSat for Measuring the MeV Extragalactic Gamma-Ray Background

The origin of Extragalactic Background (EGB) light in the 300 keV - 30 MeV energy range is an unsolved question that has persisted for more than 40 years. MAMBO (Mini Astrophysical MeV Background Observatory) is a CubeSat mission concept motivated by the realization that an instrument purpose-built for measuring the MeV EGB from a CubeSat can provide quality measurements that exceed the best that are currently available. There are two key reasons for this: (1) the EGB is so bright at MeV energies that it only requires an instrument with a small effective area and (2) the best existing measurements are compromised by instrumental background, which scales with the mass of the spacecraft/instrument. Here, small is beautiful. We present a design for a gamma-ray spectrometer capable of both providing quality measurements of the spectrum and angular distribution of the MeV EGB and meeting the tight Size, Weight, and Power (SWaP) constraints imposed by deployment on a 6U CubeSat. During a two year baseline mission, MAMBO will be able to collect measurements of the MeV EGB background that are superior to the best currently available and place important constraints on MeV EGB origin.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Progress, Performance, and Prospects of Ultra-High Resolution Microcalorimeter Spectrometers

In 2005 the LANL/NIST team used a single high-resolution microcalorimeter detector to measure the gamma-ray spectrum of a plutonium sample. After more than a decade of research and development on this topic, both the technology and our general understanding of its capabilities have advanced greatly, such that a progress review is now timely. We examine the scenario of a large-scale reprocessing plant and conclude that current non-destructive analysis (NDA) methods are inadequate to safeguard such a facility to the desired levels, leading to undesirable dependence on massspectrometry (MS) destructive analysis (DA). The development of microcalorimeter detectors is intended to close the performance gap between NDA and DA methods to address the needs of nuclear facilities.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Development of Holmium-163 electron-capture spectroscopy with transition-edge sensors

Calorimetric decay energy spectroscopy of electron-capture-decaying isotopes is a promising method to achieve the sensitivity required for electron neutrino mass measurement. The very low total nuclear decay energy (Q EC < 3 keV) and short half-life (4570 years) of 163 Ho make it attractive for high-precision electron-capture spectroscopy (ECS) near the kinematic endpoint, where the neutrino momentum goes to zero. In the ECS approach, an electron-capture-decaying isotope is embedded inside a microcalorimeter designed to capture and measure the energy of all the decay radiation except that of the escaping neutrino. We have developed a complete process for proton irradiation-based isotope production, isolation, and purification of 163 Ho. We have developed transition-edge sensors for this measurement and methods for incorporating 163 Ho into high-resolution microcalorimeters, and have measured the electron-capture spectrum of 163 Ho. Finally, we present our work in these areas and discuss the measured spectrum and its comparison to current theory.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Q-Spectroscopy

A new tool for rapid single-particle analysis in safeguards is described. This quantitative analysis tool has advantages over conventional methods for isotopic analysis of actinide-bearing samples. The method can be used to determine chemical age via 241 Am/ 241 Pu ''atomic clock''.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗