First evidence of low energy enhancement in Ge isotopes

¹ Department of Physics, University of Oslo, N-0316 Oslo, Norway
² Department of Physics, Konan University, Okamoto 8-9-1, Higashinada, Kobe 658-8501, Japan
³ Extreme Light Infrastructure Nuclear Physics, str Atomistilor nr. 407, Bucharest-Magurele, P.O.BOX MG6, Romania
⁴ National Institute for Physics and Nuclear Engineering Horia Hulubei, str Atomistilor nr. 407, Bucharest-Magurele, P.O.BOX MG6, Romania
⁵ Faculty of Physics, University of Bucharest, Bucharest, Romania
⁶ Institut d’Astronomie et d’Astrophysique, ULB, Belgium
⁷ Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550-9234, US
⁸ Cyclotron Institute, Texas A&M University, College Station, Texas 77843, USA
⁹ iThemba LABS, P.O. Box 722, 7129 Somerset West, South Africa
¹⁰ Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
¹¹ Research Center for Nuclear Physics, Osaka University, Suita, Osaka 567-0047, Japan
¹² Institute of Nuclear Research of the Hungarian Academy of Sciences (MTA Atomki), Debrecen, Hungary

^a e-mail: therese.renstrom@fys.uio.no

Published online: 28 May 2015

Abstract

The γ-strength functions and level densities of ^73,74Ge have been extracted from particle-γ coincidence data using the Oslo method. In addition the γ-strength function of ⁷⁴Ge above the neutron separation threshold, S_n = 10.196 MeV has been extracted from photoneutron measurements. When combined, these two experiments give a γ-strength function covering the energy range of ∼1-13 MeV for ⁷⁴Ge. This thorough investigation of ⁷⁴Ge is a part of an international campaign to study the previously reported low energy enhancement in this mass region in the γ-strength function from ∼3MeV towards lower γ energies. The obtained data show that both ^73,74Ge display an increase in strength at low γ energies.