A study of the 46, 48Ti( 3He, t) and 58, 60Ni( 3He, t) reactions to isobaric analogue states

Abstract

The ( 3He, t) reaction populating 0 + and 2 + states in 58, 60Cu and 46, 48V which are isobaric analogue states (IAS) of the 0 + ground states and 2 + first excited states in 58, 60Ni and 46, 48Ti have been studied at an incident 3He energy of 24.6 MeV. Triton spectra were measured for the targets 46,48Ti, natNi and 58Ni and angular distributions for the 0 + and 2 + IAS of 46, 48Ti and 58, 60Ni determined. The data were obtained using a magnetic spectrometer and position-sensitive detectors. The results have been analysed using DWBA theory. The 0 + → 0 + transitions to analogue states are described quite well using a microscopic form factor derived from a nucleon-nucleon interaction. However, with a Gaussian form, the m.s. radius of this interaction is only limited to the region 0–9 fm 2. Comparisons with data at other incident energies indicate that the strength of the effective interaction is strongly energy dependent. The Coulomb energies and ( 3He, t) angular distributions of the states assigned as the 2 + analogues in 48V and 58,60Cu are not described well by the models investigated. The 46V 2 + IAS angular distribution is reproduced by a microscopic calculation, however. The ratios of the 0 + → 2 + IAS to the 0 + → 0 + IAS transitions are used to deduce a quadrupole deformation for the valence neutrons. The difference in the quadrupole deformations of the matter and proton distributions, as determined by other means, is found to be correlated with those of the valence neutrons. Several transitions to non-analogue states are also investigated.