Wireless, low-cost, FPGA-based miniature gamma ray spectrometer Becker, E.M.; Farsoni, A.T.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2014, Letnik:
761
Journal Article
Recenzirano
Odprti dostop
A compact, low-cost, wireless gamma-ray spectrometer is a tool sought by a number of different organizations in the field of radiation detection. Such a device has applications in emergency response, ...battlefield assessment, and personal dosimetry. A prototype device fitting this description has been constructed in the Advanced Radiation Instrumentation Laboratory at Oregon State University. The prototype uses a CsI(Tl) scintillator coupled to a solid-state photomultiplier and a 40MHz, 12-bit, FPGA-based digital pulse processor to measure gamma radiation, and is able to be accessed wirelessly by mobile phone. The prototype device consumes roughly 420mW, weighs about 28g (not including battery), and measures 2.54×3.81cm2. The prototype device is able to achieve 5.9% FWHM energy resolution at 662keV.
A lightweight, low-cost multi-panel direction-sensitive radiation detector prototype has been developed at Oregon State University that is designed to be mounted on a small unmanned aerial system to ...autonomously search for radiation sources while flying close to the ground. The detection system comprises sixteen BGO-SiPM detector panels with an adjustable view angle, and signal outputs are processed in parallel in an FPGA. The minimum detectable activity was calculated to be 1.3μCi of 137Cs at 1m in under 60s. The counting response of the detector panels were characterized and found to have 4.7% relative standard deviation, indicating good uniformity in overall design and assembly. The detector was also able to estimate the direction of a 12.3μCi 137Cs source 100cm from the device center with 2.3° accuracy in a 95% confidence width of 10.8° in 60s.
A real-time FPGA-based algorithm has been developed and tested to discriminate pulse-shapes, identify beta–gamma coincidence events and collect energy spectra from xenon radioisotopes using a ...phoswich detector. The detector consists of a thin plastic scintillator (BC-400) to detect beta and conversion electrons, a CsI(Tl) crystal for measuring X-rays and gamma-rays, and a BGO crystal, which surrounds the CsI(Tl) layer, to identify scattered photons and ultimately to reduce Compton continuum in the gamma energy spectrum. In this paper, we report on the detail of the FPGA hardware design, the pulse-shape discrimination method, and the system's operational modes. In addition, our initial real-time radioxenon measurement results with the phoswich detector are presented.
A custom radiation monitoring system was developed by Oregon State University at the request of the Woods Hole Oceanographic Institute to measure radioactive cesium contaminants in the ocean waters ...near Fukushima Dai-ichi Nuclear Power Plant. The system was to be used on board the R/V Ka’imikai-O-Kanaloa during a 15 d research cruise to provide real-time approximations of radionuclide concentration and alert researchers to the possible occurrence of highly elevated radionuclide concentrations. A NaI(Tl) scintillation detector was coupled to a custom-built compact digital spectroscopy system and suspended within a sealed tank of continuously flowing seawater. A series of counts were acquired within an energy region corresponding to the main photopeak of 137Cs. The system was calibrated using known quantities of radioactive 134Cs and 137Cs in a ratio equating to that present at the reactors’ ocean outlet. The response between net count rate and concentration of 137Cs was then used to generate temporal and geographic plots of 137Cs concentration throughout the research cruise in Japanese coastal waters. The concentration of 137Cs was low but detectable, reaching a peak of 3.8 ± 0.2 Bq/L.
A phoswich detector with Compton suppression capability has been developed and tested for measuring xenon radioisotopes via a beta-gamma coincidence measurement technique. The phoswich detector has ...been designed with three scintillation layers. Beta-gamma coincidence events from radioxenon isotopes are identified when a coincidence energy absorption is detected in the first (BC-400) and second (CsI(Tl) crystal) scintillation layers. To identify and reject scattered photons from the CsI(Tl) crystal, the crystal is surrounded by a BGO scintillation layer. Our measurements show that the Compton suppression mechanism reduces the Compton continuum from 662 keV photons by 20-50% in the low-energy region of spectrum. Our beta-gamma coincidence measurements with 135 Xe and 133 Xe radioisotopes show energy resolutions (FWHM) of 13%, 46% and 24% for 250 keV, 30 keV and 80 keV gamma-ray peaks, respectively. In this paper, the detector design, assembly steps, digital pulse shape discrimination technique, and our recent measurements with radioactive lab sources and xenon radioisotopes are discussed.
A system for simultaneous beta and gamma spectroscopy Farsoni, A.T.; Hamby, D.M.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2007, Letnik:
578, Številka:
3
Journal Article
Recenzirano
A state-of-the-art radiation detection system for real-time and simultaneous spectroscopy of beta-particles and gamma-rays has been developed. The system utilizes a triple-layer phoswich detector and ...a customized Digital Pulse Processor (DPP) designed and built in our laboratory. The DPP board digitally captures the analog signal pulses and, following several digital preprocessing steps, transfers valid pulses to the host computer for further digital processing. A resolving algorithm also was developed to digitally discriminate beta and gamma events, and reconstruct separate beta and gamma-ray energy spectra with minimal crosstalk. The spectrometer has proven to be an effective tool for recording separate beta and gamma-ray spectra from mixed radiation fields. The system as a beta–gamma spectrometer will have broad-ranging applications in nuclear non-proliferation, radioactive waste management, worker safety, systems reliability, dose assessment, and risk analysis.
In this work, a well-type phoswich detector with three scintillation layers has been designed and tested for measuring atmospheric xenon radioisotopes in order to monitor nuclear explosions. The ...detector was made by optically coupling three concentric cylindrical scintillation layers (BC-400, CsI(Tl) and BGO) to a single photomultiplier tube. Beta-gamma coincidence technique was used to detect beta particles and gamma rays. Other important features of this detector are its Compton suppression capability and simple, compact and cost effective design. Our calculations and measurements with the well-type phoswich detector show that the minimum detectable concentrations are close to or below 1 mBq/m
3
for the four xenon radioisotopes.
A phoswich detector with two scintillation layers has been designed and assembled at Oregon State University. This detector is able to identify and reject Compton events and ultimately reduce the ...Compton continuum in gamma energy spectra. In this detector, CsI(Tl) crystal is used to primarily detect photoelectric events. The CsI(Tl) crystal is partially surrounded by a BGO crystal layer to capture and identify Compton-scattered photons. Both crystals are optically coupled to a single photomultiplier tube. A real-time, FPGA-based digital pulse shape analysis was developed to discriminate and reject Compton-induced pulses from the CsI(Tl) crystal. All the digital pulse processing functions including pulse shape discrimination analysis, pile-up rejection and energy measurement were implemented in an on-board FPGA device. In this paper, the results of recent measurements using radioactive lab sources will be presented and discussed.
To measure and study energy deposition of
β-particles at different depths, a triple-layer phoswich detector has been designed. The phoswich detector consists of BC-400/CaF2:Eu/BC-444 with decay time ...constants of 2.4, 940 and 264
ns, respectively, all with thicknesses corresponding to that necessary to completely stop 0.1
MeV electrons in the first layer, 1.0
MeV electrons in the second layer and 2.5
MeV electrons in the third layer. Monte Carlo N-Particle (MCNP) version 4B was used to simulate energy deposition in each layer from monoenergetic
β-particles. The simulations and measurements revealed that the traditional rise time measurement technique is not able to provide appropriate and accurate pulse shape discrimination for this type of detector.
A real-time FPGA-based algorithm has been developed and tested to discriminate pulse-shapes, identify betaagamma coincidence events and collect energy spectra from xenon radioisotopes using a ...phoswich detector. The detector consists of a thin plastic scintillator (BC-400) to detect beta and conversion electrons, a CsI(Tl) crystal for measuring X-rays and gamma-rays, and a BGO crystal, which surrounds the CsI(Tl) layer, to identify scattered photons and ultimately to reduce Compton continuum in the gamma energy spectrum. In this paper, we report on the detail of the FPGA hardware design, the pulse-shape discrimination method, and the system's operational modes. In addition, our initial real-time radioxenon measurement results with the phoswich detector are presented.
