Eur. Phys. J. A 11, 25-38 (2001)

High-spin spectroscopy of ⁶³₃₁ Ga ₃₂ and ⁶⁵₃₁ Ga ₃₄

M. Weiszflog¹, G. de Angelis², A. Axelsson³, D. Bazzacco⁴, F. Becker⁵, M. De Poli², J. Eberth⁵, C. Fahlander^{2, 6}, A. Gadea², S. Lunardi⁴, D.R. Napoli², J. Nyberg¹, C. Rossi Alvarez⁴, B. Rubio⁷, D. Rudolph⁶, S. Skoda⁵, H.G. Thomas⁵ and R. Wyss<sup>8

1</sup>  Department of Neutron Research, Uppsala University, 75121 Uppsala, Sweden
²  INFN, Laboratori Nazionali di Legnaro, 35020 Legnaro, Italy
³  Department of Radiation Sciences, Uppsala University, 75121 Uppsala, Sweden
⁴  Dipartimento di Fisica dell'Università and INFN, 35131 Padova, Italy
⁵  Institut für Kernphysik, Universität zu Köln, 50937 Köln, Germany
⁶  Lund University, 22100 Lund, Sweden
⁷  Instituto de Física Corpuscular, Valencia, Spain
⁸  The Royal Institute of Technology, 10044 Stockholm, Sweden

matthias@tsl.uu.se

(Received: 20 December 2000 / Revised version: 9 April 2001 Communicated by D. Guerreau)

Abstract
High-spin states in the nuclei ⁶³Ga and ⁶⁵Ga were studied following the reaction ³²S + ⁴⁰Ca at a reaction energy of 125 MeV and using the GASP -ray spectrometer in combination with the ISIS charged-particle detector system. In addition to low-lying negative-parity states with single-particle character, rotational-like cascades built on the 9/2⁺ and 19/2^- states have been observed in both nuclei. Sidebands with negative parity in ⁶³Ga and positive parity in ⁶⁵Ga could be established. The experimental results are compared with Total Routhian Surface calculations which describe the nuclei as moderately deformed ( ) and soft at low rotational frequencies. The highest experimentally observed positive-parity state in ⁶⁵Ga (41/2⁺) is in good agreement with the calculated crossing of the collective band with a non-collective one terminating at this spin.

PACS
21.60.Ev - Collective models.
23.20.En - Angular distribution and correlation measurements.
23.20.Lv - Gamma transitions and level energies.
27.50.+e - .

© Società Italiana di Fisica, Springer-Verlag 2001