Li6(p, p′)

Abstract

The total cross section for the 6 Li(^,^') 6 Li(3.56 MeV) reaction was measured by observing the isotropic 3.56-MeV de-excitation y rays in a 20-cm 3 Ge(Li) detector and was found to decrease slowly with energy. In a microscopic model of the reaction, this cross section depends only on the spin-isospin-dependent part Fn of the effective interaction. At energies above 34 MeV, the data are well described by a potential, Vn= Ve-ar /ar, where the range 1/a is taken to be 1.0 F, and F= 12.1 MeV. At 25 MeV, F= 11.1 MeV fits the data. The impulse approximation predicts a cross section larger than the data for the energy range of this experiment, the ratio decreasing from 2.9 at 25 MeV to 1.4 at 45 MeV. Available evidence on the spinisospin-dependent interaction is summarized. For proton energies between 23 and 52 MeV, the strength of Vu lies in the range 12.5±2.5 MeV and does not appear to vary with energy.

Charge Exchange Part of the Effective Two-Body Interaction

“…The critical potential, below which moment formation does not occur, is ITL\/A . 5 S = i expected for the singly occupied localized s state treated in this model. In addition, the density of states, while closer to that expected for U» A than the density of states of the nonparquet equations, still has much too strong a background in the region between the two peaks.…”

“…2(b)]. The cross-hatched area represents an estimate of the ratio at 20 MeV obtained by extrapolating the 7 n l cross sections measured at higher energies (23 ^E p ^ 53 MeV) by Locard et al 5 The K is required because our neglect of optical parameters is no longer justified in this case since in addition to the large difference in Q value we have different isospins in the initial and final states and hence quite possibly different optical parameters. There is another difficulty in that (a) 2 was obtained from the 6 He -* 6 Li beta decay, but 6 Be is unstable against particle emission and hence the overlap of the wave functions will not be as large as estimated from beta decay.…”