First observation of low-energy $\ensuremath{\gamma}$-ray enhancement in the rare-earth region

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

A. Simon, M. Guttormsen, A. C. Larsen, C. W. Beausang, P. Humby, J. T. Harke, R. J. Casperson, R. O. Hughes, T. J. Ross, J. M. Allmond, R. Chyzh, M. Dag, J. Koglin, E. McCleskey, M. McCleskey, S. Ota, and A. Saastamoinen

Phys. Rev. C 93, 034303 – Published 4 March 2016

Abstract

The $γ$ -ray strength function and level density in the quasi-continuum of ${}^{151, 153}{Sm}$ 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 $\approx 500$ 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.

Received 15 July 2015

DOI:https://doi.org/10.1103/PhysRevC.93.034303

Physics Subject Headings (PhySH)

Energy levels Photonuclear reactions Resonance reactions

150 ≤ A ≤ 189

Nuclear Physics

Authors & Affiliations

A. Simon^1,*, M. Guttormsen^2,†, A. C. Larsen^2,‡, C. W. Beausang², P. Humby^3,4, J. T. Harke⁵, R. J. Casperson⁵, R. O. Hughes⁵, T. J. Ross⁶, J. M. Allmond⁷, R. Chyzh⁸, M. Dag⁸, J. Koglin⁵, E. McCleskey⁸, M. McCleskey⁸, S. Ota^5,9, and A. Saastamoinen⁸

¹Department of Physics, University of Notre Dame, Indiana 46556-5670, USA
²Department of Physics, University of Oslo, N-0316 Oslo, Norway
³Department of Physics, University of Richmond, Richmond, Virginia 23171, USA
⁴Department of Physics, University of Surrey, Surrey, GU27XH, UK
⁵Lawrence Livermore National Laboratory, Livermore, California 94551, USA
⁶Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, USA
⁷Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
⁸Cyclotron Institute, Texas A&M University, College Station, Texas 77843, USA
⁹Department of Physics and Astronomy, Rutgers University, New Brunswick, New Jersey 08903, USA

^*anna.simon@nd.edu
^†magne.guttormsen@fys.uio.no
^‡a.c.larsen@fys.uio.no

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 93, Iss. 3 — March 2016

Reuse & Permissions

Access Options

Article Available via CHORUS

Download Accepted Manuscript

Author publication services for translation and copyediting assistance advertisement

Physical Review C

covering nuclear physics

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

A. Simon, M. Guttormsen, A. C. Larsen, C. W. Beausang, P. Humby, J. T. Harke, R. J. Casperson, R. O. Hughes, T. J. Ross, J. M. Allmond, R. Chyzh, M. Dag, J. Koglin, E. McCleskey, M. McCleskey, S. Ota, and A. Saastamoinen

Phys. Rev. C 93, 034303 – Published 4 March 2016

Abstract

Physics Subject Headings (PhySH)

Authors & Affiliations

Article Text (Subscription Required)

References (Subscription Required)

Issue

Access Options

Physical Review C

covering nuclear physics

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

A. Simon, M. Guttormsen, A. C. Larsen, C. W. Beausang, P. Humby, J. T. Harke, R. J. Casperson, R. O. Hughes, T. J. Ross, J. M. Allmond, R. Chyzh, M. Dag, J. Koglin, E. McCleskey, M. McCleskey, S. Ota, and A. Saastamoinen

Phys. Rev. C 93, 034303 – Published 4 March 2016

Abstract

Physics Subject Headings (PhySH)

Authors & Affiliations

Article Text (Subscription Required)

References (Subscription Required)

Issue

Access Options

Authorization Required

Other Options

Download & Share

Images

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Log In

Search

Article Lookup

Paste a citation or DOI

Enter a citation

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