Anomalous band-crossings in the N=57 isotones¹⁰³Pd and¹⁰⁵Cd

Abstract

High-spin stares of the N = 57 isotones. Io3Pd and %d. have been studied using the reactions "i!~f'~On3n)'~'Pd and 94Zr(1b0.5n)'MCd. l l ~ vhll/z p t bands in both nuclei

RDM lifetime measurements in107Cd

“…However, as pointed out in [6][7][8] the yrast sequences of such nuclei appear to show a change in collective excitation from vibrational to rotational which is associated with the population of low-, unnatural parity h 11 2 orbitals. The decay schemes of the odd-N, Cd isotopes from A = 105-123 all show collective band structures built on this negative parity orbital [9][10][11][12][13][14] and magnetic moment measurements in these nuclei have demonstrated an almost pure h 11 2 neutron character for the bandhead of these structures [15]. However, in contrast to the vibrational-like behaviour deduced for the even-even cores, the structures in the odd-A Cd isotopes have been interpreted using cranked-shell model (CSM) arguments to be rotational in nature [8][9][10][11][12][13][14] , with the h 11 2 neutron orbital weakly-coupled in a rotationaligned [16] manner to a statically (weakly) deformed core.…”

Binary-reaction spectroscopy ofMo99,100: Intruder alignment systematics inN=57<

“…Therefore as the atomic number is reduced and the Fermi surface falls lower in the g 9/2 subshell, one might expect an increased influence on alignments from the lower-⍀ Nilsson components of the g 9/2 protons. This can be explained by the position of the proton Fermi surface changing from the mid-to-high ⍀ orbitals of the g 9 Cd have also been shown to demonstrate a strong dependence on the quadrupole deformation [9]. Specifically the observation *Corresponding author.…”

“…Rotational-like sequences in the N=57 and N=58 isotones between the subshell closure at Z=40͑Zr͒ and the magic number at Z=50͑Sn͒ present particularly good laboratories with which to probe such Coriolis-driven alignment effects in weakly deformed nuclei (e.g., Refs. [7][8][9][10][11][12][13][14][15][16]). The odd-A, N=57 isotones systematically exhibit weakly deformed, decoupled bands associated with the population of the low-⍀ components of the unique-parity h 11/2 orbital [8,9].…”

“…[7][8][9][10][11][12][13][14][15][16]). The odd-A, N=57 isotones systematically exhibit weakly deformed, decoupled bands associated with the population of the low-⍀ components of the unique-parity h 11/2 orbital [8,9]. By comparing the observed increase in aligned angular momentum as the structures of these decoupled negative-parity sequences evolve with spin, it is possible to gain insight into the nature of the particles that are responsible for the alignment.…”

Identification of a high-spin isomer inMo99

“…This isomeric state is interpreted as an energetically favored, maximally aligned configuration of νh The near-yrast structure of the A ∼ 100 region with N 56 is dominated by excitations associated with the high-j "unnatural parity" proton g 9 2 and neutron h 11 2 orbitals. Decoupled, rotational sequences built on a single νh 11 2 orbital are observed in all N = 57 isotones from 2 configurations, depending on the proton number and the associated core deformation [1][2][3]. These collective rotational bands can compete with single-particle excitations formed by the favored, maximally aligned couplings of high-j proton (g 9 2 ) and neutron (h 11 2 and g 7 2 ) orbitals.…”