The low-lying level structure of 59V and 61V was investigated for the first time. The neutron knockout reaction and inelastic proton scattering were applied for 61V while the neutron knock-out ...reaction provided the data for 59V. Four and five new transitions were determined for 59V and 61V, respectively. Based on the comparison to our shell-model calculations using the Lenzi-Nowacki-Poves-Sieja (LNPS) interaction, three of the observed γ rays for each isotope could be placed in the level scheme and assigned to the decay of the first 11/2− and 9/2− levels. The (p,p′) excitation cross sections for 61V were analyzed by the coupled-channels formalism assuming quadrupole plus hexadecapole deformations. Due to the role of the hexadecapole deformation, 61V could not be unambiguously placed on the island of inversion.
Low-lying excited states in the N = 32 isotope Ar-50 were investigated by in-beam gamma-ray spectroscopy following proton- and neutron-knockout, multinucleon removal, and proton inelastic scattering ...at the RIKEN Radioactive Isotope Beam Factory. The energies of the two previously reported transitions have been confirmed, and five additional states are presented for the first time, including a candidate for a 3(-) state. The level scheme built using gamma gamma coincidences was compared to shell-model calculations in the sd-pf model space and to ab initio predictions based on chiral two- and three-nucleon interactions. Theoretical proton- and neutron-knockout cross sections suggest that two of the new transitions correspond to 2(+) states, while the previously proposed 4(1)(+) state could also correspond to a 2(+) state.
A first gamma-ray study of Cl-47,Cl-49 spectroscopy was performed at the Radioactive Isotope Beam Factory with 50 Ar projectiles at 217 MeV/nucleon, impinging on the liquid hydrogen target of the ...MINOS device. Prompt deexcitation gamma rays were measured with the NaI(T1) array DALI2(+). Through the one-proton knockout reaction Ar-50(p, 2p), a spin assignment could be determined for the low-lying states of Cl-49 from the momentum distribution obtained with the SAMURAI spectrometer. A spin-parity J(pi) = 3/2(+) is deduced for the ground state of Cl-49, similar to the recently studied N = 32 isotope K-51. The evolution of the energy difference E(1/2(1)(+)) - E (3/2(1)(+)) is compared to state-of-the-art theoretical predictions.
States in the N = 35 and 37 isotopes Ca-55,Ca-57 have been populated by direct proton-induced nucleon removal reactions from Sc-56,Sc-58 and Ca-56 beams at the RIBF. In addition, the (p, 2p) ...quasi-free single-proton removal reaction from Ca-56 was studied. Excited states in K-55, Ca-55, and Ca-57 were established for the first time via in-beam gamma-ray spectroscopy. Results for the proton and neutron removal reactions from Ca-56 to states in K-55 and Ca-55 for the level energies, excited state lifetimes, and exclusive cross sections agree well with state-of-the-art theoretical calculations using different approaches. The observation of a short-lived state in Ca-57 suggests a transition in the calcium isotopic chain from single-particle dominated states at N = 35 to collective excitations at N = 37.
The nuclear structure of Ar-51, an uncharted territory so far, was studied by the (p,2p) reaction using gamma-ray spectroscopy for the bound states and the invariant mass method for the unbound ...states. Two peaks were detected in the gamma-ray spectrum and six peaks were observed in the Ar-50+n relative energy spectrum. Comparing the results to our shell-model calculations, two bound and six unbound states were established. Three of the unbound states could only be placed tentatively due to the low number of counts in the relative energy spectrum of events associated with the decay through the first excited state of Ar-50. The low cross sections populating the two bound states of Ar-51 could be interpreted as a clear signature for the presence of significant subshell closures at neutron numbers 32 and 34 in argon isotopes. It was also revealed that due to the two valence holes, unbound collective states coexist with individual-particle states in Ar-51.
The low-lying level structure of 63V was studied for the first time by the inelastic proton scattering and the proton knock-out reaction in inverse kinematics. The comparison of the newly observed ...γ-ray transitions at 696(8) keV and 889(16) keV with our shell-model calculations using the Lenzi-Nowacki-Poves-Sieja interaction established two excited states proposed to be the first 11/2− and 9/2− levels. The (p,p′) excitation cross sections were analyzed by the coupled channel formalism assuming pure quadrupole as well as quadrupole+hexadecapole deformations. This resulted in large deformation parameters placing 63V in the island of inversion located below 68Ni.
The low-lying level structure of 63V was studied for the first time by the inelastic proton scattering and the proton knock-out reaction in inverse kinematics. The comparison of the newly observed ...γ-ray transitions at 696(8) keV and 889(16) keV with our shell-model calculations using the Lenzi-Nowacki-Poves-Sieja interaction established two excited states proposed to be the first 11/2− and 9/2− levels. The (p,p′) excitation cross sections were analyzed by the coupled channel formalism assuming pure quadrupole as well as quadrupole+hexadecapole deformations. This resulted in large deformation parameters placing 63V in the island of inversion located below 68Ni.
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