NEA-0526 MARE.

1. NAME OR DESIGNATION OF PROGRAM:  MARE.

3. NATURE OF PHYSICAL PROBLEM SOLVED

MARE calculates reaction cross sections induced by neutrons, protons, alpha particles, using a statistical model for the decay of the compound nucleus in the continuum energy range (1 MeV - 15 MeV). The theoretical background  is the evaporation theory and the Blatt-Ewing formula. Computation takes into account processes of the type (x;a,b), (x;a,b,n) where x, a, b can be either neutrons, protons, alpha particles or gamma rays  and n stands for neutrons.

4. METHOD OF SOLUTION

The model adopted is based on the following assumptions:
i) Compound nucleus processes only take place and the cross section for compound nucleus formation is equal to the reaction cross section. De-excitation happens through successive evaporations of neutrons, protons, alpha particles and gamma rays. More than three successive emissions are not admitted.
ii) The nucleus can be described as a perfect gas of nucleons whose      level density is given by the shifted Fermi gas model.
iii) If the residual nucleus after the second emission has an excitation energy above the neutron emission threshold, a neutron is emitted.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Dostrovsky's approximation is assumed to fit neutron reaction cross sections; for incident protons an estimate derived from the W.K.B. approximation is adopted; for incident gamma rays an electric dipole absorption only is considered. No discrete channels are permitted; only continuum particle emission.

6. TYPICAL RUNNING TIME

On the IBM 360/75 OS, the mean time per nucleus and per energy in the range 1-20 MeV is:
  for a process of the type (x,a) 25/100 sec;
  for a process of the type (x;a,b) or (x;a,b,c) 1-2 sec (where x;a,b can be neutrons, protons, alpha particles or gamma rays).

7. UNUSUAL FEATURES OF THE PROGRAM

MARE is designed to have very simple input when "standard parameters" (taken from systematics) are used, but parameters may optionally be specified as input by the user. The program contains the tabulation of: a) mass excesses and automatic calculation of binding energies of protons, neutrons, alpha particles; b) level density parameters for nuclei with n between 23 and 127; c) average radiation width for nuclei with n between 25 and 127.

8. RELATED OR AUXILIARY PROGRAMS: RELATED AND AUXILIARY PROGRAMS

- G. Reffo and M. Vaccari:
  MARE: A FORTRAN IV Code for Compound Nucleus Reaction Calculations
  in the Continuum
  RT/FI(72)7 (20 March 1972)

11. MACHINE REQUIREMENTS:  160k bytes

13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED:  OS, MVS/370.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

15. NAME AND ESTABLISHMENT OF AUTHOR

       M. Vaccari, G.Reffo
       Laboratorio Dati Nucleari
       Centro di Calcolo del C.N.E.N.
       Via Mazzini, 2
       40138 Bologna, Italy

File name	File description	Records
NEA0526_01.001	SOURCE PROGRAM (F4) (G-COMPILER) EBCDIC	1660
NEA0526_01.002	BLOCK DATA EBCDIC	1381
NEA0526_01.003	PROGRAM FOR READING BLOCK DATA EBCDIC	57
NEA0526_01.004	JCL FOR BLOCK DATA AND MARE EBCDIC	17
NEA0526_01.005	BLOCK DATA PROGRAM PRINTED OUTPUT	116
NEA0526_01.006	MARE SAMPLE PROBLEM INPUT DATA EBCDIC	38
NEA0526_01.007	MARE SAMPLE PROBLEM PRINTED OUTPUT	282
NEA0526_01.008	MARE SAMPLE PROBLEM PUNCHED OUTPUT EBCDIC	70