Calculation of the (γ, n) and (γ, p) cross sections for 4He in a continuum shell-model approximation

Abstract

The photonucleon reaction has been studied by using a straightforward extension of bound-state shell-model theory. Continuum wave functions are replaced by their value at the centre of small energy intervals. When this process is truncated at some maximum excitation energy, a finite set of wave functions describing the continuum is produced. Calculations are performed using a finite square well and a zero-range residual interaction in the 1p-1h space. Application of the method is illustrated by calculating the photoneutron and photoproton cross sections and angular distributions for 4He. Good agreement between the calculated cross sections and most experimental data is obtained.