Eur. Phys. J. A (2015) 51: 170
https://doi.org/10.1140/epja/i2015-15170-4

Regular Article - Experimental Physics

Experimental level densities of atomic nuclei

¹ Department of Physics, University of Oslo, N-0316, Oslo, Norway
² CENBG, CNRS/IN2P3, University of Bordeaux, B.P. 120, 33175, Gradignan, France
³ Lawrence Livermore National Laboratory, 7000 East Avenue, 94550-9234, Livermore, CA, USA
⁴ Department of Physics and Astronomy, Ohio University, 45701, Athens, Ohio, USA
⁵ CEA Saclay, DSM/Irfu/SPhN, F-91191, Cedex, France
⁶ Institut de Physique Nucleaire d’Orsay, 15 rue G. Glemenceau, 91406, Orsay Cedex, France
⁷ iThemba LABS, P.O. Box 722, 7129, Somerset West, South Africa

^* e-mail: magne.guttormsen@fys.uio.no

Received: 11 March 2015
Accepted: 8 May 2015
Published online: 23 December 2015

Abstract

It is almost 80 years since Hans Bethe described the level density as a non-interacting gas of protons and neutrons. In all these years, experimental data were interpreted within this picture of a fermionic gas. However, the renewed interest of measuring level density using various techniques calls for a revision of this description. In particular, the wealth of nuclear level densities measured with the Oslo method favors the constant-temperature level density over the Fermi-gas picture. From the basis of experimental data, we demonstrate that nuclei exhibit a constant-temperature level density behavior for all mass regions and at least up to the neutron threshold.