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Title: First observation of low-energy γ-ray enhancement in the rare-earth region

Abstract

Here, the γ-ray strength function and level density in the quasi-continuum of 151,153Sm have been measured using bismuth germanate shielded Ge clover detectors of the STARLiTeR system. The Compton shields allow an extraction of the γ strength down to unprecedentedly low γ energies of ≈ 500 keV. For the first time an enhanced low-energy γ-ray strength has been observed in the rare-earth region. In addition, for the first time both the upbend and the well-known scissors resonance have been observed simultaneously for the same nucleus. Hauser-Feshbach calculations show that this strength enhancement at low γ energies could have an impact of 2 3 orders of magnitude on the (n, γ) reaction rates for r-process nucleosynthesis.

Authors:
 [1];  [2];  [2];  [2];  [3];  [4];  [4];  [4];  [5];  [6];  [7];  [7];  [4];  [7];  [7];  [8];  [7]
  1. Univ. of Notre Dame, Notre Dame, IN (United States)
  2. Univ. of Oslo, Oslo (Norway)
  3. Univ. of Richmond, Richmond, VA (United States); Univ. of Surrey, Surrey (United Kingdom)
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. Univ. of Kentucky, Lexington, KY (United States)
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  7. Texas A & M Univ., College Station, TX (United States)
  8. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rutgers Univ., New Brunswick, NJ (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE; Research Council of Norway (NFR); National Science Foundation (NSF); European Research Council (ERC)
OSTI Identifier:
1267050
Alternate Identifier(s):
OSTI ID: 1240452; OSTI ID: 1432959
Report Number(s):
LLNL-JRNL-704138
Journal ID: ISSN 2469-9985; KB0401022; ERKBP06
Grant/Contract Number:  
AC52-07NA27344; AC05-00OR22725; NA0001801; FG02-05ER41379; PHY-1430152; 205528; 637686
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 93; Journal Issue: 3; Journal ID: ISSN 2469-9985
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Simon, Anna, Guttormsen, M., Larsen, A. C., Beausang, C. W., Humby, P., Burke, J. T., Casperson, R. J., Hughes, R. O., Ross, T. J., Allmond, James M., Chyzh, R., Dag, M., Koglin, J., McCleskey, E., McCleskey, M., Ota, S., and Saastamoinen, A. First observation of low-energy γ-ray enhancement in the rare-earth region. United States: N. p., 2016. Web. doi:10.1103/PhysRevC.93.034303.
Simon, Anna, Guttormsen, M., Larsen, A. C., Beausang, C. W., Humby, P., Burke, J. T., Casperson, R. J., Hughes, R. O., Ross, T. J., Allmond, James M., Chyzh, R., Dag, M., Koglin, J., McCleskey, E., McCleskey, M., Ota, S., & Saastamoinen, A. First observation of low-energy γ-ray enhancement in the rare-earth region. United States. doi:10.1103/PhysRevC.93.034303.
Simon, Anna, Guttormsen, M., Larsen, A. C., Beausang, C. W., Humby, P., Burke, J. T., Casperson, R. J., Hughes, R. O., Ross, T. J., Allmond, James M., Chyzh, R., Dag, M., Koglin, J., McCleskey, E., McCleskey, M., Ota, S., and Saastamoinen, A. Fri . "First observation of low-energy γ-ray enhancement in the rare-earth region". United States. doi:10.1103/PhysRevC.93.034303. https://www.osti.gov/servlets/purl/1267050.
@article{osti_1267050,
title = {First observation of low-energy γ-ray enhancement in the rare-earth region},
author = {Simon, Anna and Guttormsen, M. and Larsen, A. C. and Beausang, C. W. and Humby, P. and Burke, J. T. and Casperson, R. J. and Hughes, R. O. and Ross, T. J. and Allmond, James M. and Chyzh, R. and Dag, M. and Koglin, J. and McCleskey, E. and McCleskey, M. and Ota, S. and Saastamoinen, A.},
abstractNote = {Here, the γ-ray strength function and level density in the quasi-continuum of 151,153Sm have been measured using bismuth germanate shielded Ge clover detectors of the STARLiTeR system. The Compton shields allow an extraction of the γ strength down to unprecedentedly low γ energies of ≈ 500 keV. For the first time an enhanced low-energy γ-ray strength has been observed in the rare-earth region. In addition, for the first time both the upbend and the well-known scissors resonance have been observed simultaneously for the same nucleus. Hauser-Feshbach calculations show that this strength enhancement at low γ energies could have an impact of 2 3 orders of magnitude on the (n, γ) reaction rates for r-process nucleosynthesis.},
doi = {10.1103/PhysRevC.93.034303},
journal = {Physical Review C},
number = 3,
volume = 93,
place = {United States},
year = {2016},
month = {3}
}

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