High-pressure Xenon Detectors Research Articles

High-Pressure Xenon Detector in Nuclear Radiation Measurement System

With its excellent energy resolution and good temperature characteristics, high-pressure xenon detectors are widely used in extreme measurement environments such as high temperature and strong radiation. However, the energy resolution of the energy spectrum of the high-pressure xenon detector will be reduced or even distorted in a high-decibel noise environment. In order to better understand the noise sensitivity of high-pressure xenon detectors, this paper summarizes and analyzes the principle, development process and research status of high-pressure xenon detectors based on the literature on high-pressure xenon detector structure and performance at home and abroad. The study found that for the problem of baseline drift caused by the noise sensitivity of high-pressure xenon detectors, the traditional baseline restoration algorithm cannot effectively play a role. The adaptive baseline restoration method should be able to overcome this problem.

Baseline restoration method based on mathematical morphology for high-pressure xenon detectors

The shift of baseline has always existed in high-pressure xenon (HPXe) detectors because of the influence of external acoustic noise. This problem seriously influences the spectrometric characteristics of these detectors. A special baseline restoration method is required to remove the shift of baseline in real time. This study demonstrated that the top hat transform based on mathematical morphology can restrain the shift of baseline in digital multichannel analyzer. An improved baseline restoration (IBLR) method based on mathematical morphology was proposed and implemented in field programmable gate array (FPGA) to obtain superior baseline restoration. The structuring element of the IBLR method can be adjusted automatically in real time according to the characteristics of the baseline. Experimental results show that the IBLR method can maintain an excellent energy resolution over a wide shift range of baseline. To strengthen our conclusion, we carried out an external acoustic noise experiment on a HPXe detector. The HPXe detector with IBLR was virtually unaffected by external acoustic noise.

Large-volume and room-temperature gamma spectrometer for environmental radiation monitoring

Abstract The use of a room-temperature gamma spectrometer is an issue in environmental radiation monitoring. To monitor radionuclides released around a nuclear power plant, suitable instruments giving fast and reliable information are required. High-pressure xenon (HPXe) chambers have range of resolution and efficiency equivalent to those of other medium resolution detectors such as those using NaI(Tl), CdZnTe, and LaBr 3 :Ce. An HPXe chamber could be a cost-effective alternative, assuming temperature stability and reliability. The CEA LIST actively studied and developed HPXe-based technology applied for environmental monitoring. Xenon purification and conditioning was performed. The design of a 4-L HPXe detector was performed to minimize the detector capacitance and the required power supply. Simulations were done with the MCNPX2.7 particle transport code to estimate the intrinsic efficiency of the HPXe detector. A behavioral study dealing with ballistic deficits and electronic noise will be utilized to provide perspective for further analysis.

A plan for directional dark matter sensitivity in high-pressure xenon detectors through the addition of wavelength shifting gaseous molecules

Xenon is an especially attractive candidate for both direct WIMP and 0νββ decay searches. Although the current trend has exploited the liquid phase, the gas phase xenon offers remarkable performance advantages for: energy resolution, topology visualization, and discrimination between electron and nuclear recoils. The NEXT-100 experiment, now under construction in the Canfranc Underground Laboratory, Spain, will operate at ∼ 15 bars with 100 kg of 136Xe for the 0νββ decay search. We will describe recent results with small prototypes, indicating that NEXT-100 can provide about 0.5% FWHM energy resolution at the decay's Q value (2457.83 keV), as well as rejection of γ-rays with topological cuts. However, sensitivity goals for WIMP dark matter and 0νββ decay searches indicate the probable need for ton-scale active masses. NEXT-100 provides the springboard to reach this scale with xenon gas. We describe a scenario for performing both searches in a single, high-pressure, ton-scale xenon gas detector, without significant compromise to either. In addition, even in a single ton-scale, high-pressure xenon gas TPC, an intrinsic sensitivity to the nuclear recoil direction may exist. This plausibly offers an advance of more than two orders of magnitude relative to current low-pressure TPC concepts. We argue that, in an era of deepening fiscal austerity, such a dual-purpose detector may be possible at acceptable cost, within the time frame of interest, and deserves our collective attention.

Improving Spectroscopic Performance of a Coplanar-Anode High-Pressure Xenon Gamma-Ray Spectrometer

High-pressure xenon (HPXe) gas is a desirable radiation detection medium for homeland security applications because of its good inherent room-temperature energy resolution, potential for large, efficient devices, and stability over a broad temperature range. Past work in HPXe has produced large-diameter gridded ionization chambers with energy resolution at 662 keV between 3.5 and 4% FWHM. However, one major limitation of these detectors is resolution degradation due to Frisch grid microphonics. A coplanar-anode HPXe detector has been developed as an alternative to gridded chambers. An investigation of this detector's energy resolution is reported in this submission. A simulation package is used to investigate the contributions of important physical processes to the measured photopeak broadening. Experimental data is presented for pure Xe and Xe + 0.2%H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> mixtures, including an analysis of interaction location effects on the energy spectrum.

Simulation of γ-ray spectrometry of failed TRISO fuel

Very High Temperature Reactors (VHTR) utilize the TRISO microsphere as the fundamental fuel unit in the core. To understand better its behavior under in-core conditions, the fuel is irradiated in a controlled environment that resembles anticipated operating conditions. In this work, simulated γ-ray spectra are developed for the fission product gases that are released upon fuel failure. The simulations are based on Monte Carlo calculations of spectra assuming the use of high-purity germaniun (HPGe) and high-pressure xenon (HPXe) detectors. The γ-ray source terms for the simulations are derived from ORIGEN 2.2 fuel depletion calculations. In addition, measured detector resolution information are included in the Monte Carlo simulations to produce realistically broadened spectra. The effect of fission product release processes are incorporated in the simulation by reconstructing the Monte Carlo photon source terms using a specific gas-release model. Consequently, birth and release γ-ray spectra are constructed for the Kr and Xe gaseous fission products.

High-pressure xenon detector development at Constellation Technology Corporation

Xenon-filled ionization detectors, due to their high atomic number fill gas ( Z=54), moderate densities (∼0.3–0.5 g/cm 3) and good energy resolution (2–4% at 662 keV), fill an important niche between more familiar technologies such as NaI(Tl) scintillators and germanium detectors. Until recently, difficulties with obtaining sufficient xenon purity, reducing microphonic sensitivity, and developing low-noise electronics compatible with small ionization signals have hampered the development of this nuclear detection field. Constellation Technology Corporation, whose experience with xenon detectors goes back to the mid 1990s, has made significant progress in these areas and has developed a commercial line of detectors with active volumes ranging from small (35 g Xe) to large (1400 g Xe). Current applications for Constellation's detectors are principally in the area of defense (Unmanned Aerial Vehicles and Advanced Spectroscopic Portals), but as awareness of this technology grows, it will surely find applications in a much expanded range of fields.

High-pressure xenon ion chambers for gamma-ray spectroscopy in nuclear safeguards

There has been a long-standing need for a room-temperature gamma-ray detector system with high efficiency and adequate resolution for nuclear safeguards applications. For nuclear safeguards, measurements must resolve the uranium complex at 186keV and the plutonium complex at 414keV. The need for adequate room-temperature resolution has been met by CdZnTe detectors, but these small detectors cannot produce the efficiency needed for broad application in nuclear safeguards. The high-pressure xenon (HPXe) detector offers resolution, efficiency, intrinsic radiation resistance and temperature stability, making this detector type a viable candidate for broad application in nuclear safeguards. We will examine the current status HPXe detector systems, contrast HPXe with other detector types for nuclear safeguards applications, and discuss our efforts to improve the HPXe detector operating characteristics.

Detection sensitivity for special nuclear materials with an advanced high-pressure xenon detector and robust fitting analysis

The sensitivity for detection of two special nuclear materials, /sup 235/U and /sup 239/Pu, using an advanced high-pressure xenon detector (HPXe) and robust fitting analysis (RFA) with RobWin is experimentally determined for a set of collections with varying attenuation thicknesses of lead. These measurements provide essential information that enables comparisons with other detector systems for nuclear portal monitoring applications. Advantages of the combined use of HPXe and RFA for nuclear portal monitors are discussed, and recent progress with them is described briefly. An experiment designed to provide data from which models for nuclear portal monitor design can be grounded is described. Spectra were collected at CEA/Saclay with an HPXe unit from MEPhI for both /sup 235/U and /sup 239/Pu With attenuating thicknesses of lead ranging from zero to four millimeters. A single analysis procedure that yielded consistent results for all spectra was developed to simulate the automated application of analysis without user intervention and without advance knowledge of shielding thickness. These two spectrum series were then analyzed with RFA methodology for detection sensitivity and is reported in a form that can be used for comparison with other detector systems and for optimization of design parameters for HPXe/RFA portal monitor systems.

Pulse rise-time characterization of a high pressure xenon gamma detector for use in resolution enhancement

Abstract High pressure xenon ionization chamber detectors are possible alternatives to traditional thallium doped sodium iodide [NaI(Tl)] and hyperpure germanium as gamma-spectrometers in certain applications. Xenon detectors incorporating a Frisch grid exhibit energy resolutions comparable to cadmium/zinc/telluride (CZT) (e.g., 2% @ 662 keV) but with far greater sensitive volumes. The Frisch grid reduces the position dependence of the anode pulse rise-times, but it also increases the detector vibration sensitivity, anode capacitance, voltage requirements and mechanical complexity. We have been investigating the possibility of eliminating the grid electrode in high-pressure xenon detectors and preserving the high energy resolution using electronic rise-time compensation methods. A two-electrode cylindrical high pressure xenon gamma-detector coupled to time-to-amplitude conversion electronics was used to characterize the pulse rise-time of deposited gamma-photons. Time discrimination was used to character...

Vibrostability of high pressure xenon gamma-ray detectors

For about 20 years high-pressure xenon (HPXe) detectors have been developed for the measurement of gamma-radiation spectra in the energy range 0.1-5 MeV with high-energy resolution. These detectors have numerous advantages in comparison with germanium and scintillation detectors, but they are relatively sensitive to the influence of acoustic and mechanical vibrations. Decreasing the microphonic sensitivity is necessary for improving the characteristics of these detectors. In this paper the results of acoustic and vibration testing performed on parallel-plate and cylindrical HPXe detectors are presented. Design modifications of high-pressure xenon detectors for improved vibration stability are discussed.

High-pressure xenon detectors for gamma-ray spectrometry

The main results of long-term research on compressed xenon detector properties conducted at the laboratory of cosmic physics of MEPhI are given along with a description of the latest gamma-ray spectrometers based on this work. It is shown that using xenon as working substance, it is possible to create a gamma-ray spectrometer with high energy resolution. The construction and the main physical, technical and operation performances of xenon gamma-ray spectrometers based on ionization chambers of various configurations are described. For a gamma-ray spectrometer with a cylindrical ionization chamber and shielding grid, an energy resolution of about 14 keV (10 keV intrinsic resolution) for gamma-ray line of 662 keV is obtained. The characteristics of these detectors allow one to apply them in various fields of science and engineering, moreover, their good spectrometric properties provide the opportunity to use them for metrology measurements.

Ultra-high pressure proportional counters Part II. Xenon

Proportional counters filled with xenon-methane mixtures at ultra-high pressures have been tested since the publication of the first part of this paper. These tests have clearly demonstrated the feasibility of using large area high pressure xenon detectors for application in the hard X-ray and low energy gamma ray regions. Our measurements also indicate that the mobility of positive ions changes with gas pressure thereby affecting the gas amplification process and the anode pulse shape in proportional counters. The spatial and energy resolution of counters at high pressures depends not only on the increased fluctuations in the number of primary electrons produced and the statistics of the charge multiplication process, but also on the gas pressure, concentration of quenching gas and the presence of electro-negative impurities.

An ultra high pressure xenon detector for hard x-ray astronomy

A programme has been in progress in our laboratory to determine the performance of a cylindrical proportional counter filled with argon or xenon at pressures up to 30 atmospheres, using methane as the quenching agent. The successful operation of a prototype counter has led to the design of a large area balloon-borne detector for hard x-ray astronomy. The ultra high pressure in an array of cylindrical proportional counter modules, together with the large dimensions possible, will enable us to fabricate a detector with very high efficiency and sensitivity, capable of extending its energy response well beyond the limits of contemporary flow detectors. The details of our investigations and the proposed detector are described.

Spatial resolution in high-pressure xenon x-ray detectors

High-pressure xenon detectors used in medical x-ray scanning have high stopping power for x rays and high resolution, typically 1 mm for 50–150 keVP x rays. Industrial inspection calls for even higher spatial resolution at higher x-ray energies. The precision in localizing incident x-ray photons is limited by the spread of the primary electrons and other radiations produced by the x-ray photons in the detector. In this paper, the spatial resolution of the high-pressure xenon detector is determined by analytically modeling the interactions between the x-ray photons and Xe atoms, and calculating the spatial spread of the secondary radiation produced by the conversion electrons, bremsstrahlung, and fluorescent radiation. It is found that spatial resolution of the order of 100 μm is achievable for 320-keVP x rays in Xe at 75 atm. The spatial resolution determined in this way can be used in designing and calibrating gas detectors, and in estimating the contribution from all other experimental sources to the spatial spread of the detected signals.

Split Xenon Detector for Tomochemistry in Computed Tomography

The design of a split high-pressure xenon detector array for tomochemistry in computed tomography (CT) is described. Each detector produces a signal from the front primarily due to low energy photons and a signal from the back primarily due to high energy photons. Two methods are described whereby these signals are used to determine the photoelectric and Compton coefficients. From these, the electron density and average atomic number can be determined for each pixel in the image. These methods were tested by computer simulations of scans of a simple phantom, and the resulting Compton and photoelectric images are presented and compared with a conventional CT image. It was found that electron density and atomic number can be determined to an accuracy of better than 4%. The sensitivity to noise was studied, and it was found that the standard deviation of the mean of a 5 X 5 pixel region in the conventional image is about a factor of 3 lower than in the same region in the Compton image and about a factor of 40 lower than in the photoelectric image.