Alpha-cluster transfer from alpha-decaying nuclei

Abstract

The (d, 6Li) α-cluster pickup reaction on targets of 144Nd, 148Sm, 152Gd, 208Pb, 232Th and 238U at bombarding energies from 33 MeV to 55 MeV as well as the α-cluster stripping reaction, 208Pb( 6Li, d) at 90 Mev have been analyzed and the results compared with the known α-decay properties of 144Nd, 148Sm, 152Gd, 212Po, 232Th and 238U, respectively. The dependence of the finite-range DWBA cross sections on a number of quantities was studied : (i) the optical model parameters; (ii) the α-cluster wave function in 6Li and the influence of α + d antisymmetrization effects; (iii) the effective interaction between the deuteron and the α-particle; (iv) the α-cluster wave function in the target nucleus and its relationship to the A-dependence of nuclear matter radii. Reduced widths and spectroscopic factors extracted independently for α-transfer and α-decay agree within a factor 1.4±0.5 for appropriate choices of parameters. This confirms the validity of the reaction and decay analyses and indicates that the g.s. → g.s. transitions proceed predominantly by a direct α-transfer. Antisymmetrization effects which may influence α-decay and α-transfer differently are weak as the latter takes place primarily in the surface region of nuclei. It is estimated that about 25 % of the nuclear matter in the surface at ρ nucl ( r)/ ρ nucl (0) ≈ 0.3% is associated with α-particle matter (α-particle condensation).