RADCAP: A potential model tool for direct capture reactions

Abstract

A computer program is presented aiming at the calculation of bound and continuum states, reduced transition probabilities, phase-shifts, photo-disintegration cross sections, radiative capture cross sections, and astrophysical S-factors, for a two-body nuclear system. The code is based on a potential model of a Woods–Saxon, a Gaussian, or a M3Y, type. It can be used to calculate nuclear reaction rates in numerous astrophysical scenarios. Program summary Title of program: RADCAP (RADiative CApture) Catalogue identifier:ADSH Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ADSH Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computers: The code has been created on an IBM-PC, but also runs on UNIX machines Operating systems: WINDOWS or UNIX Program language used: Fortran-77 Memory required to execute with typical data: 8 Mbytes of RAM memory and 2 MB of hard disk space No. of bits in a word: 32 or 64 Memory required for test run with typical data: 2 MB No. of bytes in distributed program: 376 817 No. of lines in distributed program, including test data, etc.: 3054 Distribution format: tar gzip file Keywords: Potential model, photodissociation, radiative capture, astrophysical S-factors Nature of physical problem: The program calculates bound and continuum wavefunctions, phase-shifts and resonance widths, astrophysical S-factors, and other quantities of interest for direct capture reactions. Method of solution: Solves the radial Schrödinger equation for bound and for continuum states. First the eigenenergy is estimated by using the WKB method. Then, a Numerov integration is used outwardly and inwardly and a matching at the nuclear surface is done to obtain the energy and the bound state wavefunction with good accuracy. The continuum states are obtained by a Runge–Kutta integration, matching the Coulomb wavefunctions at large distances outside the range of the nuclear potential. Typical running time: Almost all the CPU time is consumed by the solution of the radial Schrödinger equation. It is about 1 min on a 1 GHz Intel P4-processor machine for a Woods–Saxon potential.