K. Siwek

In-beam gamma-ray spectroscopy of very neutron-rich nuclei: excited states in 46S and 48Ar.

We report on the first in-beam gamma-ray spectroscopy study of the very neutron-rich nucleus 46S. The N=30 isotones 46S and 48Ar were produced in a novel way in two steps that both necessarily involve nucleon exchange and neutron pickup reactions 9Be(48Ca,48K)X followed by 9Be(48K,48Ar+gamma)X at 85.7 MeV/u midtarget energy and 9Be(48Ca,46Cl)X followed by 9Be(46Cl,46S+gamma)X at 87.0 MeV/u midtarget energy, respectively. The results are compared to large-scale shell-model calculations in the sd-pf shell using the SDPF-NR effective interaction and Z-dependent modifications.

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.

Two-proton knockout from {sup 32}Mg: Intruder amplitudes in {sup 30}Ne and implications for the binding of {sup 29,31}F

gamma-ray decays from excited states in {sup 30}Ne and inclusive and exclusive cross sections were measured in the {sup 9}Be({sup 32}Mg,{sup 30}Ne+gamma)X two-proton knockout reaction at incident beam energies of 99.7 and 86.7 MeV/nucleon. The measured cross section is suppressed compared to calculations and is indicative of a reduced overlap of initial and final state wave functions in {sup 32}Mg and {sup 30}Ne. We interpret this reduction as due to large 4p4h amplitudes present in the {sup 30}Ne ground state wave function, but not {sup 32}Mg. Such large intruder components are predicted to help stabilize the heavier fluorine isotopes against neutron emission.

Isobaric Analogue States Studied in Mirrored Fragmentation and Knockout Reactions

A Gamma-ray spectroscopic study of excited states of isobaric multiplets has been performed in recent years, with a view to gaining a quantitative understanding of energy differences between excited states in terms of a range of Coulomb and other isospin breaking phenomena. Recently, the experimental programme has been augmented by a study of isobaric analogue states of mirror nuclei populated in mirrored fragmentation reactions. In this presentation, recent results on the

Mirrored Fragmentation Reactions--A New Technique for Probing Isospin Symmetry in Exotic Nuclei

T =\frac{3}{2}

Reduction of spectroscopic strength: Weakly-bound and strongly-bound single-particle states studied using one-nucleon knockout reactions

analogue states in the

Spectroscopy of Mg-36: Interplay of normal and intruder configurations at the neutron-rich boundary of the "Island of Inversion"

T_z =\pm \frac{3}{2}

CAESAR—A high-efficiency CsI(Na) scintillator array for in-beam γ‐ray spectroscopy with fast rare-isotope beams

mirror pair 53Ni/53Mn will be summarised. In this work, further strong evidence is found for the need to include an anomalous isospin-breaking two-body matrix element for angular-momentum couplings of J = 2, in addition the expected Coulomb contribution, in order to account for the experimental data.

In-beam γ-ray spectroscopy and inclusive two-proton knockout cross section measurements at N ≈ 40

Gamma decays have been observed for the first time in the Tz = −3/2 nucleus 53Ni. This represents the first gamma‐spectroscopy of a Tz = −3/2 nucleus heavier than A = 33. The nucleus was produced via a two‐step fragmentation process, along with its mirror 53Mn. Differences in excitation energy between isobaric analogue states have been calculated and a preliminary interpretation attempted; shell model calculations are required to further understand these results. This work represents the first study of isobaric analogue states via mirrored fragmentation reactions and demonstrates the power of this new technique.