The angular momentum effects in deep inelastic processes and fission have been studied in the limit of statistical equilibrium. The model consists of two touching liquid drop spheres. Angular momentum fractionation has been found to occur along the mass asymmetry coordinate. If neutron competition is included (i.e., in compound nucleus formation and fission), the fractionation occurs only to a slight degree, while extensive fractionation is predicted if no neutron competition occurs (i.e., in "fusion-fission" without compound nucleus formation). Thermal fluctuations in the angular momentum are predicted to occur due to degrees of freedom which can bear angular momentum such as wriggling, tilting, bending, and twisting. The coupling of relative motion to one of the wriggling modes, leading to fluctuations between orbital and intrinsic angular momentum, is considered first. Next the effect of the excitation of all the collective modes on the fragment spin is treated. General expressions for the first and second moments of the fragment spins are derived as a function of total angular momentum and the limiting behavior at large and small total angular momentum is examined. Furthermore, the effect of collective mode excitation on the fragment spin alignment is explored and is discussed in light of recent experiments. The relevance of the present study to the measured first and second moments of the y-ray multiplicities as well as to sequential fission angular distributions is illustrated by applying the results of the theory to a well studied heavy-ion reaction.NUCLEAR REACTIONS Studied angular momentum fractionation along mass asymmetry mode. Investigated effect of collective rotational modes on fragment spins. Equilibrium statistical treatment.
We consider the radiative capture process u+d-+ Li+ y at energies, E,~3 00 keV, that are relevant for astrophysical processes. Due to the peripheral character of the reaction, the overall normalization of the astrophysical factor S24 is entirely governed by one quantity, the asymptotic normalization coefficient Col for Li-+ u+ d. Using the recently well established value for this constant Co& = 2.3~0.12 fm ", we calculated S24 taking into account both E1 and E2 contributions. Our recommended value for S24 is 2.57 MeV nb at the most effective energy for the capture reaction in astrophysical processes, E, = 70 keV, which gives a reaction rate 0.036 cm mole ' s ' at the temperature 0.8X 10 K. We found a significant energy dependence of S24 at astrophysical energies. At energies of less than 110 keV, the E1 component dominates over the E2 component. At E, =70 keV, the E1 contribution to the total transition is about 58%%uo.
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