Effect of the α production process on the direct reaction for the 7Li projectile

Abstract

We investigate the effect of the breakup process on the direct reaction (DR) for 7Li. In order to study this effect, we introduce the theoretical ratio factor, R th, and the average value of the ratio factor is 0.92. The ratio factor is close to unity in the below-barrier region because many of the α particles separated from the breakup process of 7Li are not captured by the target nuclei. As a result, the α production cross sections become the main portion of the DR cross sections. However, the value of R th in the above-barrier region are gradually suppressed because the α particles at energies above the Coulomb-barrier energy can be captured easily by the target. Using the centerof-mass energy regions of α particles, we investigate the difference of the R th values between 6Li + 209Bi and 7Li + 209Bi systems in the above-barrier region, and we find that this difference is attributed to a reduction of the α capture cross-sections for the 7Li + 209Bi system.