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Title: Improved measurement of the half-life of the Jπ = 8- nuclear isomer 152m2 Eu

The standard γ-ray energy calibration source 152Eu is well known based on the 13.5 y decay of its ground state. Nevertheless, in addition to this decay 152Eu also has two relatively long-lived isomeric states: a 9 h Jπ=0- state at E*=46 keV and a 96 min Jπ=8- state at E*=148 keV. Here we report a new measurement of the half-lives of both of these isomeric states. Excited states in 152Eu were populated following the 154Sm (p,3n) reaction using a 25 MeV proton beam from the K-150 cyclotron at the Cyclotron Institute of Texas A&M University. Post irradiation, γ rays from the de-excitation of the long lived isomeric states were measured using the six BGO shielded high-purity germanium (HPGe) clover detectors that are part of the STARLiTeR array. The half-life of the Jπ=8- isomer 152m2Eu was obtained by measuring the decrease in intensity of the 90 keV γ ray from the cascade to the ground state. The half-life of this state was measured to be 95.8(4) min which is in agreement with and significantly more precise than the previously measured value of 96(1) min. In a manner similar to the ground state the second long-lived isomer 151m1Eu, the Jπ=0- state atmore » 46 keV, β decays to excited states in 152Gd and 152Sm. Also, the half-life of this state was measured to be 9.39(7) h using five γ-ray transitions.« less
 [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [4] ;  [4] ;  [4] ;  [4] ;  [5] ;  [6] ;  [6] ;  [6] ;  [6] ;  [6] ;  [2] ;  [2] ;  [2]
  1. University of Richmond, Richmond, Virginia (United States). Department of Physics; Univ. of Surrey, Surrey (United Kingdom). Department of Physics
  2. University of Richmond, Richmond, VA (United States). Department of Physics
  3. Univ. of Kentucky, Lexington, KY (United States). Department of Chemistry
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Physics Division
  6. Texas A & M Univ., College Station, TX (United States). Cyclotron Institute
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC05-00OR22725; FG02-05ER41379; FG02-93ER40773; AC52-07NA27344; NA0001801; FG52-09NA29467
Accepted Manuscript
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 91; Journal Issue: 2; Journal ID: ISSN 2469-9985
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC); USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20)
Country of Publication:
United States