Pion elastic and inelastic 21+ scattering on 58,60,62,64Ni at T pi =180 MeV.

Abstract

Angular distributions for {pi}{sup +} and {pi}{sup {minus}} elastic and inelastic scattering from the {ital Z}=28 closed-proton-shell nuclei {sup 58,60,62,64}Ni have been measured at an incident pion kinetic energy of 180 MeV. Values for the neutron and proton matrix elements for the transition to the {ital J}{sup {pi}}=2{sup +}{sub 1} state have been extracted using the distorted wave impulse approximation in which the {pi}{sup +} and {pi}{sup {minus}} data were fitted simultaneously and the neutron and proton vibrational transition strengths were treated as free parameters. While all transitions are predominantly collective, extracted values of {ital M}{sub {ital n}}/{ital M}{sub {ital p}} indicate increasing collectivity as a function of neutron number and are consistent with the collective limit of {ital N}/{ital Z} for {sup 64}Ni. {copyright} {ital 1996 The American Physical Society.}