Coupling of the proton-hole and neutron-particle states in the neutron-rich48K isotope

Abstract

Excited states in the Z = 19, N = 29 neutron-rich 48 K isotope have been studied using deepinelastic transfer reactions with a thick target at Gammasphere and with a thin target at the PRISMA-CLARA spectrometer. The lowest excited states were located; they involve a proton hole in the s 1/2 or d 3/2 orbital coupled to a p 3/2 neutron. A new 7.1(5) ns, 5 + isomer, analog of the 7/2 − isomer in 47 K, was identified. Based on the observed γ-decay pattern of the isomer a revised spin-parity assignment of 1 − is proposed for the ground state of 48 K.

Single-particle structure atN=29: The structure ofAr47and first spectroscopy ofSGade1, Tostevin2, Bader3 et al. 2016Phys. Rev. C15050View full textAdd to dashboardCite

“…The ground-state spin of 48 K was assigned 1 − from laserspectroscopy hyperfine structure measurements [30], confirming the earlier proposal of (1 − ) by [38] from the analysis of γ-ray decay patterns in deep-inelastic transfer reactions. For the removal to a given final state of 47 Ar, with spin and parity J − , typically several proton orbitals contribute.…”

Shell structure of potassium isotopes deduced from their magnetic moments

“…In addition, an extensive discussion was presented by Gaudefroy [17] on the energy levels and configurations of N = 27, 28 and 29 isotones in the shell-model framework and compared to the experimental observation, where available. However, the predicted spin of 2 − for 48 K, is in contradiction with I π = (1 − ) proposed by Królas et al [15]. In addition, the nuclear spin of the ground state of 50 K was proposed to be 0 − [18] in contrast to the recent βdecay studies where it was suggested to be 1 − [19].…”

“…Both interactions favor a Experimental energy spectrum of 48 K adapted from Ref. [15] using the fact that the nuclear spin is firmly established to be 1 − [26]. Results are compared to the calculated spectra from different effective interactions: SDPF-NR and SDPF-U.…”

“…In addition, an excited 2 − state is near-degenerate with the 1 − level, at E = 408 keV and E = 340 keV respectively. Considering the firmly assigned ground-state spin-parity of 48 K, and using the multipolarities deduced from the measured lifetimes of the lowest four levels by Królas et al [15], the experimental spin-parities of the four lowest excited states can now be more firmly assigned. A reasonable agreement with the calculated level scheme is shown up to 1 MeV.…”

“…Nevertheless, little and especially conflicting information is available so far for the neutron-rich potassium isotopes. Level schemes based on the tentatively assigned spins of the ground state were provided for 48 K [15] and 49 K [16]. In addition, an extensive discussion was presented by Gaudefroy [17] on the energy levels and configurations of N = 27, 28 and 29 isotones in the shell-model framework and compared to the experimental observation, where available.…”