xenon-136

xenon-136
Name	xenon-136
Mass number	136
Atomic number	54
Neutrons	82
Half life	~2.165×10^21 years (double beta decay)
Decay modes	double beta decay (to barium-136)
Natural abundance	8.87%

xenon-136 xenon-136 is a stable isotope of the noble gas xenon notable for its very long-lived double beta decay and significance in neutrino physics, cosmochemistry, and low-background experiments; researchers from Enrico Fermi Institute, Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, CERN, and Gran Sasso National Laboratory have frequently studied it. Experimental collaborations including EXO, KamLAND-Zen, LUX-ZEPLIN, XENON, and GERDA reference xenon-136 for rare-event searches, while cosmochemists at Smithsonian Institution, Max Planck Society, and Harvard University use it for isotope geochemistry. Major conferences such as the International Conference on Neutrino Physics and Astrophysics, Neutrino 2024, and meetings at American Physical Society divisions often feature results involving xenon-136.

Overview

xenon-136 is one of nine naturally occurring isotopes of xenon and is studied across disciplines including particle physics at Stanford Linear Accelerator Center, nuclear physics at TRIUMF, and planetary science at Jet Propulsion Laboratory; it is often enriched or depleted in experiments run by Oak Ridge National Laboratory, Paul Scherrer Institute, and University of Tokyo. The isotope plays a role in constraints on grand unified theories presented at institutions like Princeton University and in cosmochemical investigations by teams at California Institute of Technology and University of Oxford. Policy and funding agencies such as the National Science Foundation, European Research Council, and Department of Energy have supported xenon-136 research initiatives.

Nuclear Properties

xenon-136 has atomic number 54 and neutron number 82, corresponding to the closed neutron shell also relevant to nuclei studied at Argonne National Laboratory, RIKEN, and GSI Helmholtz Centre for Heavy Ion Research; its nuclear structure informs models from the Shell model (nuclear physics) community and theoretical groups at Institute for Nuclear Theory and Los Alamos National Laboratory. Nuclear mass measurements by teams at CERN-ISOLDE and TRIUMF constrain nuclear matrix elements used in calculations from researchers at Uppsala University and Institut de Physique Nucléaire d'Orsay. The isotope’s energy levels, spin-parity assignments, and transition probabilities are compared with predictions from models developed at University of Manchester and University of Wisconsin–Madison and cited in evaluations by National Nuclear Data Center.

Double Beta Decay

xenon-136 undergoes two-neutrino and neutrinoless double beta decay processes studied by collaborations such as EXO-200, nEXO, KamLAND-Zen, and NEXT; results inform neutrino mass hierarchy debates discussed at Neutrino 2012 and Neutrino 2018. Measurements constrain effective Majorana neutrino masses in theoretical frameworks advanced at Perimeter Institute, CERN, and Institute for Advanced Study and are interpreted alongside limits from experiments like GERDA, CUORE, and SNO+. Nuclear matrix element calculations by groups at University of Milano, Tsinghua University, and Università di Padova are essential for converting xenon-136 half-life limits into particle-physics parameters cited in reviews at Particle Data Group.

Natural Occurrence and Production

xenon-136 occurs at about 8.87% natural abundance in atmospheric xenon samples collected and analyzed by researchers at Massachusetts Institute of Technology, Scripps Institution of Oceanography, and NOAA; its isotopic ratios are used in studies by teams at Smithsonian Astrophysical Observatory and Carnegie Institution for Science. Enrichment and isotope separation are performed at facilities such as URENCO partners, experimental separations at ISTU, and research labs at Kyoto University and CEA; xenon-136 is also a fission product monitored by International Atomic Energy Agency safeguards and nuclear forensics groups at Los Alamos National Laboratory and Pacific Northwest National Laboratory.

Applications and Uses

xenon-136 is used as target material in neutrinoless double beta decay searches run by EXO and planned by nEXO and as an active medium in dark matter detectors such as XENONnT, LUX-ZEPLIN, and PandaX which are built by collaborations involving Stockholm University, University of California, Berkeley, and Shanghai Jiao Tong University. It contributes to geochronology and solar system formation models pursued at University of Arizona and Brown University and informs xenon isotope anomalies studied in meteorites by teams at Field Museum and Natural History Museum, London. Industrial and medical uses draw on expertise from GE Healthcare and Siemens Healthineers for imaging technologies, while cryogenic handling methods trace to developments at CERN and Fermilab.

Detection and Measurement Techniques

Techniques for detecting xenon-136 events employ time projection chambers and liquid xenon detectors developed by collaborations at Lawrence Livermore National Laboratory, Columbia University, and Ecole Polytechnique, as well as high-resolution mass spectrometry implemented at WHOI, NIST, and Max Planck Institute for Chemistry. Low-background counting and assay methods are conducted in deep underground laboratories such as SNOLAB, Gran Sasso National Laboratory, and Boulby Underground Laboratory by teams from Queen Mary University of London, University of British Columbia, and University of Zurich. Data analysis techniques draw on software and statistical methods from groups at CERN, MIT, and Los Alamos National Laboratory and are presented at meetings including Neutrino 2016 and Identification of Dark Matter.

Safety and Handling

Handling xenon-136 requires standard noble gas protocols implemented at Argonne National Laboratory, Oak Ridge National Laboratory, and Sandia National Laboratories including cryogenic safety practices developed at CERN and Fermilab; training programs are modeled on those at National Institutes of Health and Occupational Safety and Health Administration. Transport and storage follow regulations enforced by International Air Transport Association and U.S. Department of Transportation and safety reviews by institutional compliance offices at University of California, Santa Barbara and Imperial College London. Waste management and environmental monitoring procedures are coordinated with agencies such as Environmental Protection Agency and European Environment Agency when xenon handling occurs in research facilities.

Category:Isotopes of xenon