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Updated: Apr 6, 2026

Preparing an Isotopically Pure 229Th Ion Beam for Studies of 229mTh
Published on: May 3, 2019
Results of a Direct Search Using Synchrotron Radiation for the Low-Energy (229)Th Nuclear Isomeric Transition
Justin Jeet1, Christian Schneider1, Scott T Sullivan1
1Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA.
Abstract:
We report the results of a direct search for the (229)Th (I(π)=3/2(+)←5/2(+)) nuclear isomeric transition, performed by exposing (229)Th-doped LiSrAlF(6) crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1-2) s≲τ≲(2000-5600) s. This measurement excludes roughly half of the favored transition search area and can be used to direct future searches.
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