High resolution study of isovector negative parity states in the {sup 16}O({sup 3}He,t){sup 16}F reaction at 140 MeV/nucleon

The isovector transitions from the ground state (g.s.) of {sup 16}O to the negative parity states in {sup 16}F, i.e., the J{sup {pi}}=0{sup -} g.s., the 0.193 MeV, 1{sup -} state, the 0.424 MeV, 2{sup -} state, the 0.721 MeV, 3{sup -} state, and the 4{sup -}''stretched'' state at 6.372 MeV, were studied by using a high resolution {sup 16}O({sup 3}He,t){sup 16}F reaction at 140 MeV/nucleon. With the help of high energy resolution, these states were, for the first time, clearly resolved in a charge exchange reaction at an intermediate energy, which favorably excites spin-flip states. Angular distributions of the reaction cross sections were measured in the laboratory frame from 0 deg. to 14 deg. Parameters of phenomenological effective interactions were derived so as to reproduce these angular distributions in distorted wave Born approximation (DWBA) calculations. The angular distribution of the 0{sup -} state could be reproduced well at {theta}{sub c.m.}<10 deg. The empirical values, however, are larger by a factor of 2-2.5 in the larger angle region, where the contribution of the so-called 'condensed pion field' is expected. The high resolution also enabled the decay widths of these states to be measured.