Collective properties of the odd-mass Cs nuclei. II. Cs119,121,123,125

Abstract

Using the techniques of in-beam -ray spectroscopy, the high-spin states in the odd-mass Cs119-125 have been studied via the Cd106(O16,p2n)Cs119, Cd110-114(N14,3n)Cs121-125, and Sn116,118(B10,3n)Cs123,125 reactions on enriched, self-supporting targets. Two distinct collective features are observed in the resulting level schemes: J=2 bands built on the 112- (1h112 quasi-proton states, and J=1 bands built on the 92+ (1g92 proton-hole) states. The 92+ bandheads, believed to result from the excitation of the 1g92 proton across the Z=50 closed shell, are observed at surprisingly low energies, becoming the ground state in Cs119. The systematics of the 92+ J=1 bands are presented and discussed in terms of the particle-plus-rotor and particle-plus-vibrator models. A deformed structure relationship between the excitation of a 1g92 proton and the excitation of a pair of 1g92 protons across the Z=50 closed shell is discussed. NUCLEAR REACTIONS Cd106(O16,p2n)Cs119, Cd110-114(N14,3n)Cs121-125, Sn116,118 (B10,3n)Cs123,125; measured - coincidence, (E,); deduced level schemes in odd-mass Cs119-125, multipolarities, J. Enriched targets, Ge (Li) detectors. NUCLEAR STRUCTURE Odd-mass Cs119-125, calculated 92+ J=1 rotational bands. © 1979 The American Physical Society.