A study of the low-lying isobaric analogue states of 89Sr by means of the 88Sr (p, p) and (p, p') reactions
The isobaric analogue states of levels in 89Sr are studied here as virtual states in 89Y by means of elastic and inelastic proton scattering on 88Sr. A total of 15 analogues states is identified within a range of incident energies from 4.9 to 8.7 MeV by observing resonances in the p 0(0 +), p 1'(2 1+) and p 2'(3-) channels at several scattering angles. On-resonance angular distributions for the p'(2 +) and p'(3 1-) transitions have been measured in a number of cases. The former inelastic distributions show significantly asymmetries about 90° at energies where elastic resonances are also present suggesting the existence of direct interference processes. One example is shown of a 3 - state angular distribution where the p 2(3-) channel resonates strongly, whereas the elastic p 0 channel does not. In this case, the pattern appears symmetric, and a tentative analogue spin assignment is deduced. Simple Breit-Wigner curves have been compared with the data, and estimates of the single-particle reduced widths are given. The energetic and spectroscopic information so obtained is then compared with that from the 88Sr(d, p) 89Sr reaction performed with high resolution.