Gamma Radiation Spectrometer Research Articles

A statistical method for the assessment of metrological characteristics of reference materials

Standard reference materials of the composition and properties of substances and materials are used in both industrial and non-industrial sectors of society to ensure measurement uniformity and traceability in those types of measurements that cannot be provided using standards.
 During times of war and increased nuclear threat due to a full-scale invasion by an aggressor state, there is a need for heightened attention to the verification of ionizing radiation detection blocks, measurement channels of radiation monitoring systems, radiometers, and radiometric installations, as well as alpha, beta, and gamma radiation spectrometers.
 The aim of the paper is to demonstrate the method to evaluate the measurement uncertainty of reference materials (Europium-152 (Eu-152), Сaesium-137 (Cs-137), and Thorium-232 (Th-232)) when they are generated and calibrated according to the international regulations. The evaluation of the measurement uncertainty of a radioactive reference material with a natural half-life period is relevant and valid, considering its homogeneity properties and stability. To assess the properties, as well as the measurement uncertainty, one-variant variance analysis was performed.

Fast Neutron Measurement System Using Prompt Gamma Neutron Activation Solid Converter: Monte Carlo Study.

Measuring fast neutron emission around accelerators is important for purposes of environmental monitoring and radiation safety. It is necessary to detect two types of neutrons: thermal and fast. Fast neutron spectroscopy is commonly employed using a hydrogen-recoil proportional-counter; however, its threshold is 2 MeV. The aim of this study was to expand PGNA converters based on KCl to fulfil the need to detect neutron energies ranging from 0.02 MeV to 3 MeV. In our previous research, we established a counting system comprised of a large converter of KCl with a NaI(Tl) gamma radiation spectrometer. The KCl converter is efficient for fast neutron prompt gamma emission. The potassium naturally includes a radioisotope that emits 1.460 MeV gamma rays. The presence of the constant level of 1.460 MeV gamma ray counts offers an advantage, providing a stable background for the detector. The study was carried out using MCNP simulations of the counting system with a variety of PGNA converters based on KCl. We concluded that KCl mixtures combined with other elements, such as PGNA converters, demonstrated improved detection performance for fast neutron emissions. Furthermore, an explication of how to add materials to KCl to provide a proper converter for fast neutrons was introduced.

A Low-Cost and Semi-Autonomous Robotic Scanning System for Characterising Radiological Waste

A novel, semi-autonomous radiological scanning system for inspecting irregularly shaped and radiologically uncharacterised objects in various orientations is presented. The system utilises relatively low cost, commercial-off-the-shelf (COTS) electronic components, and is intended for use within relatively low to medium radioactive dose environments. To illustrate the generic concepts, the combination of a low-cost COTS vision system, a six DoF manipulator and a gamma radiation spectrometer are investigated. Three modes of vision have been developed, allowing a remote operator to choose the most appropriate algorithm for the task. The robot arm subsequently scans autonomously across the selected object, determines the scan positions and enables the generation of radiological spectra using the gamma spectrometer. These data inform the operator of any likely radioisotopes present, where in the object they are located and thus whether the object should be treated as LLW, ILW or HLW.

Design, characterisation, and digital linearisation of an ADC analogue front-end for gamma spectroscopy measurements

<p class="Abstract">This work presents the design, experimental characterisation, and digital post-distortion (i.e., digital linearisation) of a MHz-range ADC analogue front-end prototype for a gamma radiation spectrometry system under development at the National Center for Nuclear Research (NCBJ) in Poland. The design accounts for the electrical response of the gamma particle detector in providing signal conditioning and ADC protection against high-voltage spikes due to occasional high-energy cosmic radiation, as well as proper ADC clocking. As the front-end inevitably introduces nonlinear distortion and dynamic effects, a characterisation is performed to quantify the actual performance in terms of Total Harmonic Distortion (THD) and Effective Number of Bits (ENOB). Thus, a digital linearisation based on both static and memory polynomial models is successfully applied by means of post-distortion processing, guaranteeing a substantial improvement in THD and ENOB, and demonstrating the effectiveness of the hardware/software method for gamma radiation spectrometers. </p>

A hemispherical high-pressure xenon gamma radiation spectrometer

A prototype hemispherical high-pressure xenon gamma radiation spectrometer was designed, constructed and tested. The detector consists of a pair of concentric hemispherical electrodes contained inside a thin-walled stainless steel pressure dome. Detector performance parameters such as energy resolution, linearity and vibration sensitivity were determined and compared to previous cylindrical and planar designs. Without a Frisch grid, the hemispherical detector provides a total room temperature energy resolution of 6% @ 662 keV and is relatively insensitive to acoustic interference.

Performance and simulation of CdZnTe strip detectors as sub-millimeter resolution imaging gamma radiation spectrometers

We report /spl gamma/-ray detection performance measurements and computer simulations of a sub-millimeter pitch CdZnTe strip detector. The detector is a prototype for /spl gamma/-ray astronomy measurements in the range of 20-200 keV. The prototype is a 1.5 mm thick, 64/spl times/64 orthogonal stripe CdZnTe detector of 0.375 mm pitch in both dimensions, with approximately one square inch of sensitive area. Using discrete laboratory electronics to process signals from an 8/spl times/8 strip region of the prototype we measured good spectroscopic uniformity and sub-pitch (/spl sim/0.2 mm) spatial resolution in both x and y dimensions. We present below measurements of the spatial uniformity, relative timing and pulse height of the anode and cathode signals, and the photon detection efficiency. We simulated the photon interactions and signal generation in the strip detector and the test electronics and we compare these results to the data. The data indicate that the cathode signal-as well as the anode signal-arises primarily from the conduction electrons rather than the holes. This presents a detection efficiency limitation which must be considered in the design of strip detector systems.

Large Area Mercuric Iodide Photodetectors

Results of an investigation of large area mercuric iodide (HgI2) photodetectors are reported. Different entrance contacts were studied, including semitransparent metallic films and conductive liquids. Theoretical calculations of electronic noise of these photodetectors were compared with experimental results. HgI2 photodetectors with active area up to 4 cm2 were matched with NaI(Tl) and CsI(Tl) scintillation crystals and were evaluated as gamma-radiation spectrometers. Energy resolution of 9.3% for gamma radiation of 511 keV with a CsI(Tl) scintillator and energy resolution of 9.0% for gamma radiation of 622 keV with a NaI(Tl) scintillator have been obtained.

A True Gamma-Radiation Spectrometer

A true gamma-radiation spectrometer is described which utilizes a standard 3- by 3-in. diam NaI(Tl) scintillation detector and outputs the gamma spectrum (in photons MeV-1 cm-2 sec-1) with all spurious peaks and tails corrected. A small digital computer is utilized to accumulate the pulse-height distribution and simultaneously perform a digital filtering operation in real time.