Enhanced collectivity in 74Ni

TL;DR

This study investigates the enhanced nuclear collectivity in 74Ni using inelastic proton scattering, revealing increased deformation and weakened magicity compared to neighboring isotopes, supported by experimental and theoretical analysis.

Contribution

It provides new experimental data on 74Ni's collectivity and compares it with theoretical models, showing continued enhancement and weakened magicity in this isotope.

Findings

Deformation length of 1.04(16) fm indicates increased collectivity.

Excitation cross section measured at 14(4) mb.

Shell model and RPA calculations suggest weakened magicity in 74Ni.

Abstract

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.