Proton removal from $^{73,75}$Br to $^{72,74}$Se at intermediate energies

TL;DR

This study provides new experimental data on excited states of $^{72,74}$Se from proton removal reactions on $^{73,75}$Br, revealing insights into the reaction mechanisms and nuclear structure at intermediate energies.

Contribution

It offers detailed measurements of proton removal cross sections and partial fragmentation, highlighting the role of various angular momentum transfers and shell contributions in excited state population.

Findings

Inclusive cross sections are similar for $^{73,75}$Br proton removal.

Multiple angular momentum transfers ($l=1,2,3,4$) are involved in populating excited states.

Multi-step processes influence high-$J$ state population in proton-removal reactions.

Abstract

We report new experimental data for excited states of $^{72,74}$Se obtained from proton removal from $^{73,75}$Br secondary beams on a proton target. The experiments were performed with the Ursinus-NSCL Liquid Hydrogen Target and the combined GRETINA+S800 setup at the Coupled Cyclotron Facility of the National Superconducting Cyclotron Laboratory at Michigan State University. Within uncertainties, the inclusive cross sections for proton removal from $^{73,75}$Br on a proton target are identical suggesting that the same single-particle orbitals contribute to the proton-removal reaction. In addition, details of the partial cross section fragmentation are discussed. The data might suggest that $l = 1, 2, 3$, and 4 angular momentum transfers are important to understand the population of excited states of $^{72,74}$Se in proton removal. Available data for excited states of $^{74}$Ge populated through the $^{75}$As$(d,{}^{3}{\mathrm{He}}){}^{74}$Ge proton-removal reaction in normal kinematics suggest indeed that the $fp$ and $sd$ shell as well as the $1g_{9/2}$ orbital contribute. A comparison to data available for odd-$A$ nuclei supports that the bulk of the spectroscopic strengths could be found at lower energies in the even-even Se isotopes than in, for instance, the even-even Ge isotopes. In addition, the population of high-$J$ states seems to indicate that multi-step processes contribute to proton-removal reactions at intermediate energies in these collective nuclei.