Cs2LiYCl6:Ce (CLYC) is one of the most promising new scintillators for detecting both neutrons and gamma-rays. Its neutron and gamma-ray discrimination capability using pulse-shape analysis has drawn ...much attention, and there is significant interest in its use in field applications. For such applications, compact and low-power readout electronics capable of exploiting the pulse-shape discrimination (PSD) capabilities of CLYC will be essential. A readout system centered around a PSD-capable application specific integrated circuit (ASIC) that is well-suited for use with CLYC has been characterized, tested, and validated. As part of this study, automated analysis of CLYC data collected with a fast waveform digitizer extracted optimized charge integration windows for PSD. Additionally, several different CLYC samples were studied in order to gain understanding of the dependance of pulse shapes on parameters such as crystal size, 6Li enrichment level, crystal packaging, and choice of PMT. Extremely good PSD performance was obtained from CLYC scintillator and the ASIC-based readout system.
The Los Alamos National Laboratory designed and built Mars Odyssey Neutron Spectrometer (MONS) has been operating and collecting data from February 2002 to the present. MONS measures the neutron ...leakage albedo from galactic cosmic ray bombardment of Mars. These signals can indicate the presence of near-surface water deposits on Mars, and can also be used to study properties of the seasonal polar CO2 ice caps. This work outlines a new analysis of the MONS data that results in new and extended time-series maps of MONS thermal and epithermal neutron data. The new data are compared to previous publications on the MONS instrument. We then present preliminary results studying the inter-annual variability in the polar regions of Mars based on 8 Mars-Years of MONS data from the new dataset.
•New processing of Mars Odyssey Neutron Spectrometer data, covering 2002–2017•Neutrons provide information on near-surface water deposits and seasonal CO2 cycle.•Extracted counting rates for 8 Mars Years enables study of inter-annual variability.•Documentation of analysis procedure and usage of new dataset presented•Impacts of MY 28 global dust storm observed at the Northern seasonal cap in MY 29
Cs2LiLaBr6:Ce3+(CLLB) is an elpasolite scintillator that offers excellent linearity and gamma-ray energy resolution and sensitivity to thermal neutrons with the ability to perform pulse-shape ...discrimination (PSD) to distinguish gammas and neutrons. Our investigation of CLLB has indicated the presence of intrinsic radioactive alpha background that we have determined to be from actinium contamination of the lanthanum component. We measured the pulse shapes for gamma, thermal neutron, and alpha events and determined that PSD can be performed to separate the alpha background with a moderate figure of merit of 0.98. We also measured the electron-equivalent-energy of the alpha particles in CLLB and simulated the intrinsic alpha background from 227Ac to determine the quenching factor of the alphas. A linear quenching relationship Lα=Eα×q+L0 was found at alpha particle energies above 5MeV, with a quenching factor q=0.71MeVee/MeV and an offset L0=−1.19MeVee.
Effects of proton-induced radiation damage on CLYC and CLLBC performance Mesick, K.E.; Bartlett, K.D.; Coupland, D.D.S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2019, Letnik:
948, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Cerium-doped Cs2LiYCl6 (CLYC) and Cs2LiLaBrxCl6−x (CLLBC) are scintillators in the elpasolite family that are attractive options for resource-constrained applications due to their ability to detect ...both gamma rays and neutrons within a single volume. Space-based detectors are one such application, however, the radiation environment in space can over time damage the crystal structure of the elpasolites, leading to degraded performance. We have exposed 4 samples each of CLYC and CLLBC to 800 MeV protons at the Los Alamos Neutron Science Center. The samples were irradiated with a total number of protons of 1.3×109, 1.3×1010, 5.2×1010, and 1.3×1011, corresponding to estimated doses of 0.14, 1.46, 5.82, and 14.6 kRad, respectively on the CLYC samples and 0.14, 1.38, 5.52, and 13.8 kRad, respectively on the CLLBC samples. We report the impact these radiation doses have on the light output, activation, gamma-ray energy resolution, pulse shapes, and pulse-shape discrimination figure of merit for CLYC and CLLBC.
Galactic cosmic rays undergo complex nuclear interactions with nuclei within planetary bodies that have little to no atmosphere. Radiation transport simulations are a key tool used in understanding ...the neutron and gamma ray albedo coming from these interactions and tracing these signals back to geochemical composition of the target. We study the validity of the code Geant4 for simulating such interactions by comparing simulation results to data from the Apollo 17 Lunar Neutron Probe Experiment. Different assumptions regarding the physics are explored to demonstrate how these impact the Geant4 simulation results. In general, all of the Geant4 results overpredict the data; however, certain physics lists perform better than others. In addition, we show that results from the radiation transport code MCNP6 are similar to those obtained using Geant4.
Key Points
Neutron and gamma ray spectroscopy of planetary bodies provides information about hydrogen abundance and geochemical composition
Radiation transport simulations of GCR interactions with these bodies are a key tool to predict and interpret data from such measurements
In this paper we benchmark Geant4 simulations with the Apollo 17 Lunar Neutron Probe Experiment data
The coupling of Cs2LiYCl6:Ce (CLYC) scintillator to silicon photon converters has been evaluated with the goal of investigating replacements for the traditional photomultiplier tube (PMT) in small ...handheld spectrometers. Energy spectra produced under irradiation by a range of gamma-ray and neutron sources were collected with CLYC mounted to several avalanche photodiodes, PIN photodiodes, and silicon photomultipliers. The performance for both gamma rays and neutrons was compared to that obtained by coupling CLYC to PMTs. None of the silicon devices evaluated provide comparable performance to that of a PMT with CLYC. This is attributed to the photon-detection efficiency of the silicon detectors over the wavelength range of CLYC emissions, as well as the noise characteristics of the devices.
Cs
2LiYCl
6:Ce (CLYC) is one of the most promising new scintillators for detecting both neutrons and gamma-rays. Its neutron and gamma-ray discrimination capability using pulse-shape analysis has ...drawn much attention, and there is significant interest in its use in field applications. For such applications, compact and low-power readout electronics capable of exploiting the pulse-shape discrimination (PSD) capabilities of CLYC will be essential. A readout system centered around a PSD-capable application specific integrated circuit (ASIC) that is well-suited for use with CLYC has been characterized, tested, and validated. As part of this study, automated analysis of CLYC data collected with a fast waveform digitizer extracted optimized charge integration windows for PSD. Additionally, several different CLYC samples were studied in order to gain understanding of the dependance of pulse shapes on parameters such as crystal size,
6Li enrichment level, crystal packaging, and choice of PMT. Extremely good PSD performance was obtained from CLYC scintillator and the ASIC-based readout system.
The Sudbury Neutrino Observatory (SNO) used an array of {sup 3}He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active ...({nu}{sub x}) {sup 8}B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54{sub -0.31}{sup +0.33}(stat){sub -0.34}{sup +0.36}(syst)x10{sup 6} cm{sup -2} s{sup -1}, in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields {delta}m{sup 2}=7.59{sub -0.21}{sup +0.19}x10{sup -5} eV{sup 2} and {theta}=34.4{sub -1.2}{sup +1.3} degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.
Scintillation efficiency of low-energy nuclear recoils in noble liquids plays a crucial role in interpreting results from some direct searches for weakly interacting massive particle (WIMP) dark ...matter. However, the cause of a reduced scintillation efficiency relative to electronic recoils in noble liquids remains unclear at the moment. We attribute such a reduction of scintillation efficiency to two major mechanisms: (1) energy loss and (2) scintillation quenching. The former is commonly described by Lindhard’s theory and the latter by Birk’s saturation law. We propose to combine these two to explain the observed reduction of scintillation yield for nuclear recoils in noble liquids. Birk’s constants
kB for argon, neon and xenon determined from experimental data are used to predict noble liquid scintillator’s response to low-energy nuclear recoils and low-energy electrons. We find that energy loss due to nuclear stopping power that contributes little to ionization and excitation is the dominant reduction mechanism in scintillation efficiency for nuclear recoils, but that significant additional quenching results from the nonlinear response of scintillation to the ionization density.
A Cs2LiYCl6:Ce-based advanced radiation monitoring device Budden, B.S.; Stonehill, L.C.; Dallmann, N. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2015, Letnik:
784
Journal Article
Recenzirano
Cs2LiYCl6:Ce3+ (CLYC) scintillator has gained recent interest because of its ability to perform simultaneous gamma spectroscopy and thermal neutron detection. Discrimination between the two incident ...particle types owes to the fundamentally unique emission waveforms, a consequence of the interaction and subsequent scintillation mechanisms within the crystal. Due to this dual-mode detector capability, CLYC was selected for the development of an Advanced Radiation Monitoring Device (ARMD), a compact handheld instrument for radioisotope identification and localization. ARMD consists of four 1in.-right cylindrical CLYC crystals, custom readout electronics including a suitable multi-window application specific integrated circuit (ASIC), battery pack, proprietary software, and Android-based tablet for high-level analysis and display. We herein describe the motivation of the work and engineering design of the unit, and we explain the software embedded in the core module and for radioisotope analysis. We report an operational range of tens of keV to 8.5MeV with approximately 5.3% gamma energy resolution at 662keV, thermal neutron detection efficiency of 10%, battery lifetime of up to 10h, manageable rates of 20kHz; further, we describe in greater detail time to identify specific gamma source setups.
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