Eur. Phys. J. A (2006) 30: 541-549
https://doi.org/10.1140/epja/i2006-10151-4

Nuclear Structure and Reactions

High-spin excitations of ⁸⁴ ₃₅Br₄₉ and ⁸⁵ ₃₅Br₅₀: Mapping the proton sub-shells towards ⁷⁸Ni

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: astier@csnsm.in2p3.fr

Received: 25 September 2006
Accepted: 28 November 2006
Published online: 18 December 2006

Abstract

The ^{84, 85}Br nuclei have been produced as fission fragments in the fusion reaction ¹⁸O + ²⁰⁸Pb at 85MeV bombarding energy and studied with the Euroball IV array. The high-spin states of the odd-odd ⁸⁴Br nucleus have been identified for the first time, the observed structure being built on the known 6^- isomeric state. High-spin states of ⁸⁵Br have been observed up to 5.4MeV excitation energy and spin I ∼ 21/2. From angular correlation analysis, spin values have been assigned to most of the ⁸⁵Br excited states up to 4MeV. None of these excited states has been found to exhibit a delayed decay having T _1/2 > 10ns. All the observed states in ^{84, 85}Br can be described by various proton excitations involving at least the two sub-shells ( πf _5/2 and πp _3/2) located just above the Z = 28 shell closure.