High-spin structures and alignment properties in126Ce

Abstract

Excited states in 126 Ce have been observed with the GAMMASPHERE ␥-ray detector array, used in conjunction with the MICROBALL charged-particle detector. The reaction 64 Zn( 64 Zn, xpn␣) ͑beam energy 260 MeV͒ was used to populate a wide range of nuclei in the neutron-deficient region with AϷ120. 126 Ce was populated via the 2p evaporation channel. The three previously observed bands have been extended to higher spins and some other structures have been identified. The yrast band shows evidence of a delayed neutron alignment occurring at a rotational frequency Ϸ0.5 MeV/ប as observed in the neighboring odd-A nucleus 127 Pr. One of the two excited bands shows evidence for a similar crossing at a slightly lower frequency and also exhibits a sudden gain in alignment at ϭ0.57 MeV/ប. The third band may involve the coupling of a ␥-vibrational state. All three rotational bands are discussed in terms of standard and extended cranked shell model calculations.

Projected shell model study of the yrast bands of neutron-deficient126–130Ce isotopes

“…The experimental study of excitation energy spectra in the neutron-deficient cerium isotopes has been at the centre stage of nuclear physics in recent years [1][2][3][4][5][6][7][8][9][10]. The γ -ray spectroscopy of these nuclei is dominated by rotational bands, built on the ground and low-lying excited states.…”

“…The γ -ray spectroscopy of these nuclei is dominated by rotational bands, built on the ground and low-lying excited states. Recently, excited states in 126 Ce [4] have been observed with the GAMMASPHERE γ -ray detector array, used in conjunction with the MICROBALL charged-particle detector. The energy spectra of [126][127][128][129][130] Ce are known correctly at least up to 26h.…”

“…The energy spectra of [126][127][128][129][130] Ce are known correctly at least up to 26h. In 126 Ce [4], the energy spectrum is available up to a spin of 34h, whereas in 130 Ce [8,10] the yrast band is available up to a spin of 26h. Aligned angular momenta have been studied in [124][125][126][127][128][129][130] Ce [1,4,6,11].…”

“…In 126 Ce [4], the energy spectrum is available up to a spin of 34h, whereas in 130 Ce [8,10] the yrast band is available up to a spin of 26h. Aligned angular momenta have been studied in [124][125][126][127][128][129][130] Ce [1,4,6,11]. The yrast structures of even-even neutron-deficient cerium nuclei show evidence for rotational alignment of π(h 11/2 ) 2 quasiproton pairs at a well-defined rotational frequency in the range 0.3-0.4 MeV/h.…”

“…In the past, some theoretical attempts [4,6,[9][10][11]13] have been employed to study the high-spin states and electromagnetic properties in cerium isotopes, taking one isotope at a time. For example, Wilson et al [4] used cranked shell model for studying the excitation energy spectra in 126 Ce only and were successful in reproducing the observed experimental spectra within desirable accuracy. Todd et al [11] interpreted the experimental data of 130 Ce nucleus in terms of the cranking model by assuming prolate deformation.…”