Study of $\Delta$ excitations in medium-mass nuclei with peripheral heavy ion charge-exchange reactions

Abstract

Isobaric single charge-exchange reactions, changing nuclear charges by one unit but leaving the mass partitions unaffected, have been for the first time investigated by peripheral collisions of ${}^{112}$Sn ions accelerated up to 1\textit{A} GeV at the GSI facilities. The high-resolving power of the FRS spectrometer allows us to obtain $(p,n)$-type isobaric charge-exchange cross sections with an uncertainty of $3.5\%$ and to separate quasi-elastic and inelastic components in the missing-energy spectra of the ejectiles. The inelastic component is associated to the excitation of the $\Delta$(1232) isobar resonance and the emission of pions in s-wave both in the target and projectile nucleus, while the quasi-elastic contribution is associated to the nuclear spin-isospin response of nucleon-hole excitations. An apparent shift of the $\Delta$-resonance peak of $\sim$63 MeV is observed when comparing the missing-energy spectra obtained from the measurements with proton and carbon targets. A detailed analysis, performed with a theoretical model for the reactions, indicates that this observation can be simply interpreted as a change in the relative magnitude between the contribution of the excitation of the resonance in the target and in the projectile.

References in corpus (5)

• Neutron-Rich Nuclei in Heaven and Earth
• Critical Density and Impact of $\Delta (1232)$ Resonance Formation in Neutron Stars
• Isotopic and velocity distributions of Bi produced in charge-pickup reactions of 208Pb at 1 A GeV
• Nuclear fragmentation and charge-exchange reactions induced by pions in the $\Delta$-resonance region
• The Delta N -> NN transition in finite nuclei

Cited by in corpus (5)

• Charge radii, moments and masses of mercury isotopes across the N = 126 shell closure
• Systematic study of Δ(1232) resonance excitations using single isobaric charge-exchange reactions induced by medium-mass projectiles of Sn
• Interactions of $\omega$-Mesons in Nuclear Matter and with Nuclei
• A study of the elastic $\pi N$ scattering at finite baryon density
• Study of Nucleon Charge-Exchange Processes at ${}^{12}$C Fragmentation with an Energy of 300 MeV/Nucleon