Innovative concept for a major breakthrough in atmospheric radioactive xenon detection for nuclear explosion monitoring
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Innovative concept for a major breakthrough in atmospheric radioactive xenon detection for nuclear explosion monitoring G. Le Petit • A. Cagniant • M. Morelle • P. Gross • P. Achim • G. Douysset • T. Taffary C. Moulin
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Received: 1 February 2013 Ó The Author(s) 2013. This article is published with open access at Springerlink.com
Abstract 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, 131mXe, 133m Xe, 133Xe and 135Xe, 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. Four different monitoring CTBT systems, ARIX, ARSA, SAUNA, and SPALAXTM have been developed in order to sample and to measure them with high sensitivity. The latest developed by the French Atomic Energy Commission (CEA) is likely to be drastically improved in detection sensitivity (especially for the metastable isotopes) through a higher sampling rate, when equipped with a new conversion electron (CE)/X-ray coincidence spectrometer. This new spectrometer is based on two combined detectors, both exhibiting very low radioactive background: a well-type NaI(Tl) detector for photon detection surrounding a gas cell equipped with two large passivated implanted planar silicon chips for electron detection. It is characterized by a low electron energy
G. Le Petit (&) A. Cagniant P. Gross P. Achim G. Douysset T. Taffary C. Moulin CEA, DAM, DIF, 91297 Arpajon, France e-mail: [email protected] M. Morelle Canberra Semiconductor NV, Olen, Belgium
threshold and a much better energy resolution for the CE than those usually measured with the existing CTBT equipments. Furthermore, the compact geometry of the spectrometer provides high efficiency for X-ray and for CE associated to the decay modes of the four relevant radioxenons. The paper focus on the design of this new spectrometer and presents spectroscopic performances of a prototype based on recent results achieved from both radioactive xenon standards and air sample measurements. Major improvements in detection sensitivity have been reached and quantified, especially for metastable radioactive isotopes 131mXe and 133mXe with a gain in minimum detectable activity (about 2 9 10-3 Bq) relative to current CTBT SPALAXTM system (air sampling frequency normalized to 8 h) of about 70 and 30 respectively. Keywords Radioactive xenon Beta/conversion electron-X-ray/photon coincidence SPALAXTM Silicon detector CTBT
Introduction Since the opening for signature of the Comprehensive Test Ban
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