Beyond the N = 50 shell closure: High-spin excitations of 87Kr and ground-state spin of 87Br

M. -G. Porquet; Ts. Venkova; A. Astier; I. Deloncle; A. Prévost; F. Azaiez; A. Buta; D. Curien; O. Dorvaux; G. Duchêne; B. J. P. Gall; F. Khalfallah; I. Piqueras; M. Rousseau; M. Meyer; N. Redon; O. Stézowski; R. Lucas; A. Bogachev

doi:10.1140/epja/i2006-10050-8

2022 Impact factor 2.7

Hadrons and Nuclei

Eur. Phys. J. A (2006) 28: 153-159
https://doi.org/10.1140/epja/i2006-10050-8

Nuclear Structure and Reactions

Beyond the N = 50 shell closure: High-spin excitations of ⁸⁷Kr and ground-state spin of ⁸⁷Br

M. -G. Porquet¹^*, Ts. Venkova², A. Astier¹, I. Deloncle¹, A. Prévost¹, F. Azaiez³, A. Buta³, D. Curien³, O. Dorvaux³, G. Duchêne³, B. J. P. Gall³, F. Khalfallah³, I. Piqueras³, M. Rousseau³, M. Meyer⁴, N. Redon⁴, O. Stézowski⁴, R. Lucas⁵ and A. Bogachev⁶

¹ CSNSM IN2P3-CNRS and Université Paris-Sud, 91405, Orsay, France
² INRNE, BAS, 1784, Sofia, Bulgaria
³ IPHC, IN2P3-CNRS and Université Louis Pasteur, 67037, Strasbourg Cedex 2, France
⁴ IPNL, IN2P3-CNRS and Université Claude Bernard, 69622, Villeurbanne Cedex, France
⁵ CEA/Saclay, DSM/DAPNIA/SPhN, 91191, Gif-sur-Yvette Cedex, France
⁶ JINR, Joliot-Curie 6, 142080, Dubna, Moscow region, Russia

^* e-mail: porquet@csnsm.in2p3.fr

Received: 1 March 2006
Accepted: 11 May 2006
Published online: 12 June 2006

Abstract

The ⁸⁷Kr nucleus has been produced as fission fragment in the fusion reaction ¹⁸O + ²⁰⁸Pb at 85MeV bombarding energy and studied with the Euroball IV array. High-spin states of this neutron-rich isotope have been identified for the first time. Its level scheme has been obtained up to 6.3MeV excitation energy and spin I ∼ 23/2ℏ. Its structure is interpreted by analogy with those of the heavier isotones. The proposed configurations involve both proton and neutron excitations from several sub-shells located close to the Fermi levels, particularly νd _5/2, πp _3/2 f _5/2 and πg _9/2. Moreover, a revised spin value of 5/2^- for the ⁸⁷Br ground state is proposed.