Nucleon-alpha reactions in nuclei

Abstract

The experimental data on nucleon-alpha reactions to discrete and continuum states are reviewed, together with the theories that have been proposed to account for them. At low energies the compound-nucleus mechanism predominates, and as the energy increases the pre-equilibrium and direct processes become more likely. These theories are described and the results of typical calculations compared with the experimental data. Particular attention is devoted to J-dependent and spectator effects, and to the competition between the triton pick-up and alpha knock-out mechanisms.

Validation of an optical potential for incident and emitted low-energy $$\alpha $$-particles in the $$A\sim 60$$ mass range

“…Such stretched limits have been considered due to missing of certain (see Sect. 4.2) measured α-emission spectra that are usually analyzed in order to obtain reliable values of this PE parameter [2,80,81]; they are also related to an average between a formerly found range 0.09-0.2 in the 27 ≤ A ≤ 123 region [82], and further ϕvalues of 0.25-0.3 [83,84]. Nevertheless, the NLD and PE effects are shown firstly to prove that only the α-particle OMP is the main HF parameter within the energy range ≤ 12 MeV where the most recent and precise (n, α) data remain truly under-predicted.…”

“…The due consideration of DI role within the α-emission in both neutron-and proton-induced reactions is obviously leading to an increase beyond the PE+HF predictions. Moreover, since the beginning of '90s it is concluded that the pickup instead of knockout has the main DI contribution to the low-lying levels in ( p, α) and (n, α) reactions ( [2,80,100] and Refs. therein).…”

Exclusive studies of 130–270 MeVHe3- and 200-MeV proton-induced reactions onAl27

“…Light-charged-particle (LCP: H and He isotopes) emission has been accounted for by preequilibrium [20][21][22] and coalescence [23] models. However, these approaches do not include IMF emission.…”

Analysis of (p, α) and (p,3He) cross-sections to continuum states by the Feshbach-Kerman-Koonin multistep direct theory

“…One of the reactions most frequently used to study alpha-clustering in nuclei is the p; reaction, and many analyses of the differential cross-sections and analysing powers of this reaction to discrete states have been made [3] using either the triton pick-up or the alpha-particle knock-out models. Both models give rather similar results [5,4], but nuclear structure arguments favour the pick-up model.…”