Use of STAX data in global-scale simulation of Xe atmospheric background.

A global-scale simulation of the Xe atmospheric background is automated at the French National Data Center (NDC) for the purpose of categorizing the radionuclide measurements of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System (IMS). These simulations take into account Xe releases from all known major industrial emitters in the world, compiled from the literature and described as constant values. Emission data measured directly at the stack of the Institute for Radio Elements (IRE), a medical isotope production facility located in Fleurus (Belgium), were implemented in the simulations with a time resolution of 15 minutes.

6 months of radioxenon detection in western Europe with the SPALAX-New generation system - Part 2: Atmospheric transport modelling.

Atmospheric transport modeling has been used to interpret the unprecedented number of multi-isotope detections of radioxenons observed during the six months of the qualification process by the Comprehensive Nuclear-Test-Ban Treaty Organization of the new SPALAX-NG system (Système de Prélèvement Automatique en Ligne avec l'Analyse du Xénon - Nouvelle Génération). Highest Xe activity concentrations were found to be systematically associated with the concomitant measurement of several other radioxenons at the prevailing wind direction of north/northeast pointing to the Institute for Radio Elements (IRE), a medical isotope production facility located in Fleurus (Belgium). The lowest Xe activity concentrations were not associated with a prevailing wind direction or other radioxenons, indicating the contribution of distant sources (global background).

6 months of radioxenon detection in western Europe with the SPALAX-New generation system - Part1: Metrological capabilities.

The SPALAX-NG is a new-generation system that is designed to detect radioactive xenon at trace levels in the atmosphere following a nuclear explosion or civilian source release. This new system formed part of a validation program led by the Provisional Technical Secretary of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) Organization. In this study, the first SPALAX-NG unit was tested for six months between October 2018 and April 2019 at the CEA/DIF premises near Paris, France.

Low-level laboratory measurement of xenon radionuclides: Electron-photon versus photon measurements.

Radioactive xenon (mainly Xe, Xe, Xe and Xe) are tracked as markers of nuclear weapons testing. The CEA has developed the PIPSBox, a measurement cell able to detect electrons emitted by xenon nuclides. Combined with an ultra-low background γ spectrometer, electron detection capacities allow reaching minimum detectable activities (MDA) for a 3-day long measurement of about 0.

SPALAX NG: A breakthrough in radioxenon field measurement.

Lessons-learned from 10 years of noble gas stations operation and dedicated R&D allowed the design of a New Generation of station. In order to produce 60m air equivalent Xenon samples every 8h, it implements: (i) larger sampler unit for Xenon extraction (2 compressors and 8 nitrogen membranes), (ii) new noble gas adsorbent (Ag@ZSM5), (iii) hardened components and (iv) new high resolution coincidence low background spectrometer (HPGe/PIPSBox). Station expected radioxenon sensitivity is lower than 0.

Ground surface ultralow background spectrometer: Active shielding improvements and coincidence measurements for the Gamma spectrometer.

The ultralow background versatile spectrometer GAMMA has been optimized with the following shielding improvements: (i) optimized nitrogen injection flux of 300Lh, and (ii) cosmic veto configuration with 9 scintillating plates. These improvements allow a reduction of 39% of the normalized integral background count rate down to 2.7±0.

SPALAX new generation: New process design for a more efficient xenon production system for the CTBT noble gas network.

The SPALAX (Système de Prélèvement Automatique en Ligne avec l'Analyse du Xénon) is one of the systems used in the International Monitoring System of the Comprehensive Nuclear Test Ban Treaty (CTBT) to detect radioactive xenon releases following a nuclear explosion. Approximately 10 years after the industrialization of the first system, the CEA has developed the SPALAX New Generation, SPALAX-NG, with the aim of increasing the global sensitivity and reducing the overall size of the system. A major breakthrough has been obtained by improving the sampling stage and the purification/concentration stage.

Spalax™ new generation: A sensitive and selective noble gas system for nuclear explosion monitoring.

In the context of the verification regime of the Comprehensive nuclear Test ban Treaty (CTBT), CEA is developing a new generation (NG) of SPALAX™ system for atmospheric radioxenon monitoring. These systems are able to extract more than 6cm(3) of pure xenon from air samples each 12h and to measure the four relevant xenon radioactive isotopes using a high resolution detection system operating in electron-photon coincidence mode. This paper presents the performances of the SPALAX™ NG prototype in operation at Bruyères-le-Châtel CEA centre, integrating the most recent CEA developments.

An introduction to γ(3) a new versatile ultralow background gamma spectrometer. Background description and analysis.

The γ(3) setup has been designed as a versatile, high sensitivity spectrometry platform. State-of-the art techniques have been implemented to reduce its background to minimum level even though the system is installed at ground level. The shield design and background performance of the setup are presented.

On the use of (127)Xe standards for the quality control of CTBTO noble gas stations and support laboratories.

(127)Xe has a longer half-life than (131m)Xe, it can be easily purely produced and it is present in the environment at very low level. For these reasons, (127)Xe is supposed to be a convenient quality control radionuclide for remote noble gas stations of the International Monitoring System (IMS) network. As CEA/DAM has recently developed two new photon/electron setups for low-level detection of (131m)Xe, (133m)Xe, (133)Xe and (135)Xe, we took the opportunity to test these setups for the measurement of a (127)Xe standard.

Improvements of low-level radioxenon detection sensitivity by a state-of-the art coincidence setup.

The ability to quantify isotopic ratios of 135, 133 m, 133 and 131 m radioxenon is essential for the verification of the Comprehensive Nuclear-Test Ban Treaty (CTBT). In order to improve detection limits, CEA has developed a new on-site setup using photon/electron coincidence (Le Petit et al., 2013.

Long-term performances of the ⁹⁵ZR/⁹⁵Nb chronometer for nuclear events dating.

The present work reports on a long-term analysis of the performances of the (95)Zr/(95)Nb chronometer for dating a nuclear event. Taking benefit of a recent Profiency Test Exercise, a sample containing a standardized mixture of fission products has been measured repeatedly with a low background HPGe spectrometer during a period extending up to one year with the aim of assessing the accuracy of the various zero-time determinations. Evaluation of the uncertainties associated to these evaluations was performed using a Monte Carlo approach.

Innovative concept for a major breakthrough in atmospheric radioactive xenon detection for nuclear explosion monitoring.

The verification regime of the comprehensive test ban treaty (CTBT) is based on a network of three different waveform technologies together with global monitoring of aerosols and noble gas in order to detect, locate and identify a nuclear weapon explosion down to 1 kt TNT equivalent. In case of a low intensity underground or underwater nuclear explosion, it appears that only radioactive gases, especially the noble gas which are difficult to contain, will allow identification of weak yield nuclear tests. Four radioactive xenon isotopes, Xe, Xe, Xe and Xe, are sufficiently produced in fission reactions and exhibit suitable half-lives and radiation emissions to be detected in atmosphere at low level far away from the release site.

Performance assessment by Monte Carlo simulations of a prospective assembly of up to three HPGe detectors designed for superior detection efficiency and sensitivity.

The present work reports on the results of Monte Carlo simulations performed with MCNP on an assembly of two HPGe detectors facing each other regarding detector efficiencies. Report is also made when a third detector is added to the previous configuration from below. Moreover cross talk between detectors is investigated and found of limited impact.

Some unexpected behaviours of PTW/Nucletron well-type ionization chambers.

Some unexpected behaviours of PTW/Nucletron well-type ionization chambers have been discovered. A significant undesired detection volume is present in the region surrounding the electrical terminals. A finite-element code has been used to compute electrical fields in this region, and it showed that the magnitude of the undesired volume was dependent on the electrical connector type.

Comparison of air kerma standards of LNE-LNHB and NPL for 192Ir HDR brachytherapy sources: EUROMET project no 814.

An indirect comparison has been made in the air kerma standards for high dose rate (HDR) 192Ir brachytherapy sources at the Laboratoire National Henri Becquerel (LNHB) and the National Physical Laboratory (NPL). The measurements were carried out at both laboratories between November and December 2004. The comparison was based on measurements using well-type transfer ionization chambers and two different source types, Nucletron microSelectron HDR Classic and version 2.

Influence of ambient humidity on the current delivered by air-vented ionization chambers revisited.

The influence of ambient humidity on the current delivered by a vented ionization chamber has been re-investigated. A Nucletron 077.091 well-type chamber together with a (192)Ir HDR brachytherapy source was enclosed in a climatic test chamber and the current was recorded for various humidity values.

Comparison of dosimetric standards of USA and France for HDR brachytherapy.

A bilateral comparison of national dosimetric standards for high dose rate brachytherapy has been conducted between the Laboratoire National Henri Becquerel and the University of Wisconsin Accredited Dosimetry Calibration Laboratory. A complete overview of the methods that are currently in use to establish the two national standards is given. The comparison has been carried out using well-type transfer ionization chambers.

Determination of the (76)Ge double beta decay Q value.

The Q value of the (76)Ge double beta decay has been determined by measuring the masses of (76)Ge and (76)Se in a Penning trap using neon- and fluorinelike ions. The obtained masses are 75.921 402 758(96) u and 75.