Systematic study of {\Delta}(1232) resonance excitations using single isobaric charge-exchange reactions induced by medium-mass projectiles of Sn

TL;DR

This study uses the fragment separator FRS to measure isobaric charge-exchange reactions in Sn isotopes at 1A GeV, revealing insights into { extDelta}(1232) resonance excitations and nuclear response, with implications for future resonance studies.

Contribution

First measurement of charge-exchange cross sections in Sn isotopes at high energy, separating quasi-elastic and inelastic components related to baryonic resonances.

Findings

Observation of quenching in quasi-elastic component.

Evidence that baryonic resonances can be excited in nuclei.

Potential for detailed resonance dynamics studies with advanced detectors.

Abstract

The fragment separator FRS has been for the first time used to measure the (n,p) and (p,n)-type isobaric charge-exchange cross sections of stable 112,124Sn isotopes accelerated at 1A GeV with an uncertainty of 3% and to separate quasi-elastic and inelastic components in the missing-energy spectra of the ejectiles. The inelastic contribution can be associated to the excitation of isobar {\Delta}(1232) resonances and to the pion emission in s-wave, both in the target and projectile nuclei, while the quasi-elastic contribution is associated to the nuclear spin-isospin response of nucleon-hole excitations. The data lead to interesting results where we observe a clear quenching of the quasi-elastic component and their comparisons to theoretical calculations demonstrate that the baryonic resonances can be excited in the target and projectile nuclei. To go further in this investigation, we propose to study the excitation of baryonic resonances taking advantage of the combination of high-resolving power magnetic spectrometers with the WASA calorimeter. These new measurements will allow us to determine the momenta of the ejectiles and pions emitted in coincidence after the single isobaric charge-exchange collisions, providing us unique opportunities to study the evolution of the baryonic resonance dynamics with the neutron-proton asymmetry through the use of exotic radioactive ion beams.