Eur. Phys. J. A 12, 129-133 (2001)

Short Note

First measurements of yrast excitations in ¹³⁷I and the missing 12⁺ isomer in ¹³⁶Te

A. Korgul¹, W. Urban¹, T. Rzaca-Urban¹, M. Górska², J.L. Durell³, M.J. Leddy³, M.A. Jones³, W.R. Phillips³, A.G. Smith³, B.J. Varley³, M. Bentaleb⁴, E. Lubkiewicz⁴, N. Schulz⁴, I. Ahmad⁵ and L.R. Morss<sup>5

1</sup>  Institute of Experimental Physics, Warsaw University, ul.Hoza 69, 00-681 Warszawa, Poland
²  Instituut voor Kern- en Stralingsfysica, Katholieke Universiteit Leuven, B-3001 Heverlee, Belgium
³  Schuster Laboratory, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
⁴  Institut de Recherches Subatomiques UMR7500, CNRS-IN2P3 and Université Louis Pasteur, 67037 Strasbourg, France
⁵  Argonne National Laboratory, Argonne, IL 60439, USA

urban@fuw.edu.pl

(Received: 6 June 2001 / Revised version: 23 September 2001 Communicated by D. Schwalm)

Abstract
The ¹³⁷I nucleus, populated in the spontaneous fission of ²⁴⁸Cm has been studied by means of prompt -ray spectroscopy using the EUROGAM2 array. Medium-spin yrast excitations in ¹³⁷I were observed for the first time. The experimental level scheme is compared to the shell model calculation with modified Kuo-Herling interaction. The theoretical predictions differ significantly from the experimental results, indicating that the excitation pattern in ¹³⁷I deviates significantly from the shell model scheme.

PACS
23.20.Lv - Gamma transitions and level energies.
21.60.Cs - Shell model.
25.85.Ca - Spontaneous fission.
27.60.+j - .

© Società Italiana di Fisica, Springer-Verlag 2001