arXiv subjects

M. D. Bowen

Publications and source records attributed to M. D. Bowen.

3 recordsLinked to original sources

arXiv2010

Enhanced collectivity in 74Ni

The neutron-rich nucleus 74Ni was studied with inverse-kinematics inelastic proton scattering using a 74Ni radioactive beam incident on a liquid hydrogen targetat a center-of-mass energy of 80 MeV. From the measured de-excitation gamma-rays, the population of the first 2+ state was quantified. The angle-integrated excitation cross section was determined to be 14(4) mb. A deformation length of delta = 1.04(16) fm was extracted in comparison with distorted wave theory, which suggests that the enhancement of collectivity established for 70Ni continues up to 74Ni. A comparison with results of shell model and quasi-particle random phase approximation calculations indicates that the magic character of Z = 28 or N = 50 is weakened in 74Ni.

nucl-ex↗

arXiv2008

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

We report on the first in-beam $γ$-ray spectroscopy of \nuc{23}{Al} using two different reactions at intermediate beam energies: inelastic scattering off \nuc{9}{Be} and heavy-ion induced one-proton pickup, \nuc{9}{Be}(\nuc{22}{Mg},\nuc{23}{Al}$+γ$)X, at 75.1 MeV/nucleon. A $γ$-ray transition at 1616(8) keV -- exceeding the proton separation energy by 1494 keV -- was observed in both reactions. From shell model and proton decay calculations we argue that this $γ$-ray decay proceeds from the core-excited $7/2^+$ state to the $5/2^+$ ground state of \nuc{23}{Al}. The proposed nature of this state, $[\nuc{22}{Mg}(2^+_1) \otimes πd_{5/2}]_{7/2+}$, is consistent with the presence of a gamma-branch and with the population of this state in the two reactions.

nucl-ex↗

arXiv2006

Measurement of excited states in 40Si and evidence for weakening of the N=28 shell gap

Excited states in 40Si have been established by detecting gamma-rays coincident with inelastic scattering and nucleon removal reactions on a liquid hydrogen target. The low excitation energy, 986(5) keV, of the 2+[1] state provides evidence of a weakening in the N=28 shell closure in a neutron-rich nucleus devoid of deformation-driving proton collectivity.

nucl-ex↗