Eur. Phys. J. A (2004) 22: 241-252
https://doi.org/10.1140/epja/i2004-10037-5

The ν9/2[404] orbital and the deformation in the A ∼ 100 region

¹ Laboratoire de Physique Subatomique et de Cosmologie[:EORGNAME:], [:ORGNAME:]IN2P3-CNRS/Université Joseph Fourier, F-38026, Grenoble Cedex, France
² Institute of Experimental Physics, Warsaw University, ul. Hoża 69, PL-00-681, Warszawa, Poland
³ Institut Laue-Langevin, F-38042, Grenoble Cedex, France
⁴ Schuster Laboratory, Department of Physics and Astronomy, University of Manchester, M13 9PL, Manchester, UK
⁵ Argonne National Laboratory, 60439, Argonne, IL, USA
⁶ Institut de Recherches Subatomiques UMR7500, CNRS-IN2P3 et Université Louis Pasteur, F-67037, Strasbourg, France

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

Received: 10 March 2004
Accepted: 2 June 2004
Published online: 9 November 2004

Abstract

A T _1/2 = 16(2)ns isomeric level, populated in the spontaneous fission of ²⁴⁸Cm, has been found in ¹⁰¹Zr at 941.8keV in a measurement of prompt γ-rays using the EUROGAM2 array. The level is interpreted as a K-isomer corresponding to the 9/2[404] neutron-hole excitation. The quadrupole moment, Q ₀ = 3.6(4)eb, deduced for the new band indicates a large deformation of β₂ = 0.38(4), which is produced by a specific shape-coexistence mechanism. This is another observation of the ν9/2[404] orbital in the mass A ∼ 100 region, confirming the presence of the effect reported first in our previous work. The 9/2[404] neutron-hole excitation is also confirmed in the ⁹⁷Sr nucleus and the deformation β₂ = 0.44(2) is determined for this configuration. The properties of the 9/2[404] neutron orbital and its influence on the onset of deformation in the A ∼ 100 region are discussed.