K. Hosier

In-beam γ-ray spectroscopy at the proton dripline: 23Al

Abstract We report on the first in-beam γ-ray spectroscopy of the proton-dripline nucleus 40Sc using two-nucleon pickup onto an intermediate-energy rare-isotope beam of 38Ca. The 9Be(38Ca,40Sc+γ)X reaction at 60.9 MeV/nucleon mid-target energy selectively populates states in 40Sc for which the transferred proton and neutron couple to high orbital angular momentum. In turn, due to angular-momentum selection rules in proton emission and the nuclear structure and energetics of 39Ca, such states in 40Sc then exhibit γ-decay branches although they are well above the proton separation energy. This work uniquely complements results from particle spectroscopy following charge-exchange reactions on 40Ca as well as 40Ti EC/ β + decay which both display very different selectivities. The population and γ-ray decay of the previously known first ( 5 − ) state at 892 keV and the observation of a new level at 2744 keV are discussed in comparison to the mirror nucleus and shell-model calculations. On the experimental side, this work shows that high-resolution in-beam γ-ray spectroscopy is possible with new generation Ge arrays for reactions induced by rare-isotope beams on the level of a few μb of cross section.

Inverse-kinematics one-proton pickup with intermediate-energy beams: The {sup 9}Be ({sup 20}Ne,{sup 21}Na+{gamma})X reaction

The possibility of studying particle-like states near the Fermi surfaces of exotic nuclei by using measurements of heavy-ion-induced single-nucleon pickup reactions with in-flight separated rare-isotope beams is discussed. The analysis of an exploratory data set for the intermediate-energy {sup 9}Be({sup 20}Ne,{sup 21}Na)X proton pickup reaction measured using a {sup 20}Ne beam at 63 MeV per nucleon is reported. The data are compared with expectations based on model calculations of the transfer reaction cross sections and the {sup 21}Na residue spectroscopy prediction by the sd-shell model. The measured cross sections are broadly consistent with these expectations.