Eur. Phys. J. A (2006) 27: 257-262
https://doi.org/10.1140/epja/i2005-10273-1

Letter

New information on the T_1/2 = 47 s isomer in the ¹³⁶I nucleus

¹ Faculty of Physics, Warsaw University, ul.Hoża 69, 00-681, Warsaw, Poland
² Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, 700064, Kolkata, India
³ Department of Physics, The University of Burdwan, 713104, Burdwan, India
⁴ Department of Physics and Astronomy, University of Manchester, M13 9PL, Manchester, UK
⁵ Laboratoire de Physique Subatomique et de Cosmologie, IN2P3-CNRS/Université J. Fourier, F-38026, Grenoble Cedex, France
⁶ Institut Laue-Langevin, 6 rue Jules Horowitz, F-38042, Grenoble, France
⁷ Argonne National Laboratory, 60439, Argonne, IL, USA

^* e-mail: urban@fuw.edu.pl

Received: 12 September 2005
Accepted: 10 April 2006
Published online: 4 May 2006

Abstract

The ¹³⁶I nucleus, populated in the spontaneous fission of ²⁴⁸Cm, was studied by means of prompt γ-ray spectroscopy using the EUROGAM2 array. The observation in this work of the 42.6keV prompt-γ, M1 + E2 transition de-exciting the 7^- level in ¹³⁶I indicates that this level, interpreted as the configuration, does not correspond to the T = 47s, β-decaying isomer in ¹³⁶I. The isomer is placed 42.6keV below the 7^- level. It has spin 6^- and is interpreted as the configuration. This and other members of both multiplets can be reproduced properly only if one assumes that the πd _5/2 orbital in ¹³⁶I is located 400keV lower than in ¹³³Sb. Possible mechanisms causing this effect are discussed.