A prototype detection system for atmospheric monitoring of xenon radioisotopes (original) (raw)
Related papers
Improved β-γ Coincidence Detector For Radioxenon Detection
Proceedings of the 27th …, 2005
The Automated Radioxenon Analyzer/Sampler (ARSA), built by Pacific Northwest National Laboratory (PNNL), can collect and detect several radioxenon isotopes. ARSA is very sensitive to 133 Xe, 131m Xe, 133m Xe and 135 Xe due to the compact high efficiency β-γ coincidence detector it uses. For this reason it is an excellent treaty monitoring and environmental sampling device. Although the system is shown to be both robust and reliable, based on several field tests, it is also complex due to a detailed photomultiplier tube gain matching regime. This complexity is a problem from a maintenance and quality assurance/quality control (QA/QC) standpoint. To reduce these issues a simplified β−γ coincident detector has been developed. A comparison of three different well detectors has been completed. In addition, a new plastic scintillator gas cell was constructed. The new simplified detector system has compared favorably with the original ARSA design in spectral resolution and efficiency and is significantly easier to setup and calibrate.
A radioxenon detection system using PIPS and CZT
Journal of Radioanalytical and Nuclear Chemistry, 2018
This paper introduces and describes the initial characterizations of a prototype beta-gamma coincidence detection system that utilizes a PIPSBox and two coplanar CdZnTe detectors for atmospheric radioxenon identification and nuclear test ban treaty verification. Coincidences between four independent detecting bodies are identified in real time via a custom coincidence module implemented in a field-programmable gate array. The system is compact, maintains simple readout electronics, and provides high resolution radiation detection at room temperature operation. Preliminary measurements using 137 Cs and 131m Xe were conducted to optimize various system parameters to achieve optimal energy resolution of key spectral features. The purpose of this research was to explore the utility of these materials and methods for radioxenon monitoring in the International Monitoring System.
Triple coincidence radioxenon detector
2004
The Automated Radioxenon Sampler/Analyzer (ARSA) built by Pacific Northwest National Laboratory (PNNL) is one of the world's most sensitive systems for monitoring the four radioxenon isotopes 133 Xe, 133m Xe, 131m Xe, and 135 Xe. However, due to size, weight, and power specifications appropriate to meet treaty-monitoring requirements, the ARSA is unsuitable for rapid deployment using modest transportation means. To transition this technology to a portable unit that can be easily and rapidly deployed can be achieved by significant reductions in size, weight and power consumption if concentration were not required. As part of an exploratory effort to reduce both the size of the air sample and the gas processing requirements PNNL has developed an experimental nuclear detector to test and quantify the use of triple coincidence signatures (beta, conversion electron, x-ray) from two of the radioxenon isotopes (135 Xe and 133 Xe) as well as the more traditional beta-gamma coincidence signatures used by the ARSA system. The additional coincidence requirement allows for reduced passive shielding, and makes it possible for unambiguous detection of 133 Xe and 135 Xe in the presence of high 222 Rn backgrounds. This paper will discuss the experimental setup and the results obtained for a 133 Xe sample with and without 222 Rn as an interference signature.
Intercomparison experiments of systems for the measurement of xenon radionuclides in the atmosphere
Applied Radiation and Isotopes, 2004
Radioactive xenon monitoring is one of the main technologies used for the detection of underground nuclear explosions. Precise and reliable measurements of 131m Xe, 133g Xe, 133m Xe, and 135g Xe are required as part of the International Monitoring System for compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). For the first time, simultaneous testing of four highly sensitive and automated fieldable radioxenon measurement systems has been performed and compared to established laboratory techniques. In addition to an intercomparison of radioxenon monitoring equipment of different design, this paper also presents a set of more than 2000 measurements of activity concentrations of radioactive xenon made in the city of Freiburg, Germany in 2000. The intercomparison experiment showed, that the results from the newly developed systems agree with each other and the equipment fulfills the fundamental requirements for their use in the verification regime of the CTBT. For 24-h measurements, concentrations as low as 0.1 mBq m À3 were measured for atmospheric samples ranging in size from 10 to 80 m 3 . The 133 Xe activity concentrations detected in the ambient air ranged from below 1 mBq m À3 to above 100 mBq m À3 .
Measurements of ambient radioxenon levels using the automated radioxenon sampler/analyzer (ARSA)
2001
The Pacific Northwest National Laboratory has developed an Automated Radioxenon Sampler/Analyzer (ARSA) in support of the Comprehensive Nuclear-Test-Ban-Treaty (CTBT) to measure four radioxenon isotopes: 131m Xe, 133m Xe, 133g Xe, and 135g Xe. This system uses a beta-gamma coincidence counting detector to produce two-dimensional plots of gamma-energy versus beta-energy. Betas and conversion electrons (CE) are detected in a cylindrical plastic scintillation cell and gamma and X-rays are detected in a surrounding NaI(Tl) scintillation detector. The ARSA has been field tested at several locations to measure the radioxenon concentrations. Most recently it has been deployed at the Institut für Atmosphärische Radioaktivität in Freiburg, Germany. During the first 4 months of 2000 the measured 133 Xe concentrations have varied between 0.0±0.1 and 110±10 mBq/m 3 air. The longer lived 131m Xe (T 1/2 = 11.9 d) and short lived 135 Xe (T 1/2 = 9.1 h) have also been detected in small quantities, while 133m Xe concentrations have been consistent with zero. Minimum detectable concentration (MDC) calculations for 133g Xe fell well below the 1 mBq per standard-cubic-meter of air requirement adopted by the CTBT Preparatory Commission. 1 A description of the radioxenon detector, the concentration and MDC calculations and preliminary results of the field test in Germany are presented.
Contribution to the development of atmospheric radioxenon monitoring
Journal of Radioanalytical and Nuclear Chemistry, 2008
Within the frame of Comprehensive Nuclear-Test Ban Treaty (CTBT), this paper deals with the development of the new techniques necessary for the xenon monitoring requested by the CTBT. An automatic system called SPALAX , devoted to the on-site sampling and measurement was developed by French atomic energy commission (CEA). Analytical methods and equipments have been studied at our laboratory, using dual X--spectrometry in order to get independent means with better sensitivity within a robust quality assurance program. In the case of a wide number of potential existing sources and depending on meteorological conditions, several solutions can be arrived at.
Gain calibration of a β/γ coincidence spectrometer for automated radioxenon analysis
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2004
Detection and measurement of atmospheric radioxenon is an important component of international monitoring systems for nuclear weapons testing. Monitoring stations separate xenon from air and perform isotopic analysis of the radioxenon. In one such radioxenon measurement scheme, the isotopes of interest are identified by coincident spectroscopy of electrons and photons in a b=g coincidence spectrometer (BGCS). The b spectrometer is a plastic scintillator, manufactured as a cylindrical cell containing the separated xenon sample. This cell is surrounded by the NaI(Tl) g spectrometer. We report here the development of a calibration process for the BGCS suitable for use in remote sampling systems. This procedure is based upon g-ray Compton scattering, resulting in a true coincident signal in both detectors, generation of electrons over a wide energy range that matches the energy distribution of electrons from radioxenon decay, and a relative insensitivity to source location. In addition to gain calibration, this procedure determines the resolution of the b detector as a function of energy. r
2000
The Automated Radioxenon Sampler/Analyzer (ARSA) developed at the Pacific Northwest National Laboratory for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) measures four radioxenon isotopes, 131m Xe, 133m Xe, 133g Xe, and 135g Xe. The system produces three sample histograms and three background histograms daily. The analysis of the sample histograms in conjunction with the background histograms is accomplished with a data analyzer that displays various one-and two-dimensional beta-gamma histograms. It also calculates the radioxenon concentrations and the minimum-detectable-concentrations (MDC) for each sample. This paper will describe the software program along with data formats, various software controllable parameters, and calculations.
Radioxenon Measurements with the Phoswatch Detector System
2009
Many of the radioxenon detector systems used in the International Monitoring System (IMS) and in other applications employ beta/gamma coincidence detection to achieve high sensitivity. In these systems, the coincidence detection is implemented by requiring simultaneous signals from separate beta and gamma detectors. While very sensitive to small amounts of radioxenon, this approach requires careful calibration and gain matching of several detectors and photomultiplier tubes. An alternative approach is the use of a phoswich detector in which beta-gamma coincidences are detected by pulse shape analysis. The phoswich requires only a single photomultiplier tube and thus is easier to set up and calibrate, and can be assembled into a more compact and robust system.
Redesigned β–γ radioxenon detector
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007
The Automated Radio-xenon Sampler/Analyzer (ARSA), designed by Pacific Northwest National Laboratory (PNNL) collects and detects several radioxenon isotopes, and is used to monitor underground nuclear explosions. The ARSA is very sensitive to 133 Xe, 131m Xe, 133m Xe, and 135 Xe (o1 mBq/SCM) [M. Auera et al., Wernspergera, Appl. Radiat. 6 (2004) 60] through use of its compact high efficiency b-g coincidence detector. For this reason, it is an excellent treaty monitoring system and it can be used as an environmental sampling device as well. Field testing of the ARSA has shown it to be both robust and reliable, but the nuclear detector requires a detailed photomultiplier tube (PMT) gain matching regime difficult to implement in a field environment. Complexity is a problem from a maintenance and quality assurance/quality control (QA/QC) standpoint, and efforts to reduce these issues have led to development of a simplified b-g coincident detector. The new design reduces the number of PMT's and the complexity of the calibration needed in comparison to the old design. New scintillation materials (NaI(Tl), CsI(Na), and CsI(Tl)) were investigated and a comparison of three different gamma sensitive well detectors has been completed. A new plastic-scintillator gas cell was constructed and a new method of forming the scintillator gas cell was developed. The simplified detector system compares favorably with the original ARSA design in spectral resolution and efficiency and is significantly easier to set up and calibrate. The new materials and configuration allow the resulting b-g coincidence detector to maintain the overall performance of the ARSA type b-g detector while simplifying the design. Published by Elsevier B.V.