3. DESCRIPTION OF PROGRAM OR FUNCTION
CCRMN is a program for calculating complex reactions of a medium-heavy nucleus with six light particles. In CCRMN, the incoming and outgoing particles can be neutrons, protons, 4He, deuterons, tritons and 3He. In CCRMN, we calculate all the reactions in the first, second, third, ..., up to tenth emitting processes. CCRMN is valid in 1--100 MeV energy region, it can give correct results for optical model quantities and all kinds of reaction cross sections in first, second, ..., up to tenth emitting processes.
The output data of CCRMN include total cross section; elastic scattering cross section and its angular distribution; total reaction (or nonelastic) cross section; radiative capture cross section; (x,x') reaction cross section and (x,x1,x2) reaction cross section, where x, x', x1 and x2 can be neutron, proton, 4He, deuteron, triton or 3He. To compare with experimental data conveniently, we also give the sum of the cross sections of all reactions that lead to the same residual nucleus, usually called as the isotope yields cross sections. These cross sections refer to activation or transmutation processes.
The CCRMN code is constructed within the framework of optical model, pre-equilibrium statistical theory based on the exciton model (with some changes by Zhang et al) and the evaporation model. In the first, second, and third emitting processes, we consider pre-equilibrium emission and evaporation; in the fourth to tenth emitting process, we consider only evaporation. For emission of composite particles, we adopted a pickup reaction mechanism introduced by Zhang et al. In the calculation of state densities for the exciton model, we accommodate the Pauli principle. All nuclear level densities required in the evaporation model are calculated by the formula of Gilbert and Cameron. The inverse reaction cross sections of the emitted particles used in statistical theory are calculated from the optical model. In CCRMN, for gamma-ray emission, in addition to the evaporation we also consider pre-equilibrium emission; and the partial widths are calculated based on the giant dipole resonance model with one or two resonances.
In the optical model calculation, we frequently adopt the phenomenological optical potential of Beccetti and Greenless (the parameters are usually given by a program for automatically searching for the optimum optical model parameters). The CCRMN code can also do microscopic optical potential calculations based on Skyrme force and the phenomenological optical potential calculation with CH89 or CH86 parameters for the neutron and proton channels.
The CCRMN code does not calculate direct reactions, but it can accept direct reaction cross sections calculated by other programs as input for six outgoing channels in the first process. First, CCRMN subtracts the input direct cross sections from the total reaction cross section and then adds them to corresponding statistical cross sections.
In CCRMN, we do not directly do the Hauser-Feshbach calculation, but it can accept the compound-nucleus elastic scattering cross section and its angular distribution calculated by other programs as input. CCRMN adds them to the shape elastic scattering cross section and its angular distribution respectively, and subtracts the input compound-nucleus elastic scattering cross section from the total reaction cross section. At the same time, we change the lower limit of the integration of excited energy in the first emitted process at the emitting channel corresponding to the incoming channel from zero to the first excited level energy.