1. NAME AND TITLE

MECC-7: Medium-Energy Intranuclear Cascade Code System.

AUXILIARY ROUTINES

MECC-7 Cascade data generator.

I4C: Cascade Data Analysis, combined form of 4 routines: Analysis I, Analysis II, Evaporation, and Angular Momentum.

NUCON: CS update code.

CONV: BCD-to-binary converter for data libraries.

ANG: Angular momentum distribution calculation.

Non-standard library subroutines.

DATA LIBRARIES

CS: Nuclear Configuration Data and Cross Sections for MECC-7.

ET: Evaporation Table for EVAP.

Originally packaged as MECC-3 (1971), MECC-7 is the latest in this series of ORNL intranuclear cascade code development.

2. CONTRIBUTOR

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV; IBM 360/75/91. Non-standard library subroutines are in Assembly Language.

4. NATURE OF PROBLEM SOLVED

MECC-7 calculates the results of nuclear reactions caused by a medium-high energy particle colliding with a nucleus. The incident particles may be protons or neutrons with energies from about 100 to 2500 MeV or charged pions with energies from about 100 to 1500 MeV. Target nuclei may be any element heavier than carbon. MECC-7 writes a history tape containing data on the properties of the particles escaping from the nucleus as a result of the particle-nucleus collision. The data consist of the type of escaping particles, their energies, and angles of emission.

I4C utilizes the data on the MECC-7 history tape to calculate particle multiplicities and various cross sections, such as the nonelastic cross section or the doubly-differential cross section for energy-angle correlated distributions. I4C also carries the nuclear reaction through an additional phase, that of evaporation, and calculates evaporation residual nuclei (radiochemical) cross sections and the particle multiplicities and energy spectra of particles "boiled off" from the nucleus after the cascade has stopped.

5. METHOD OF SOLUTION

The code system is based on the assumption that nuclear reactions involving high-energy particles can be described in terms of particle-particle collisions within the nucleus. The life history of each individual particle is traced as the incident particle, and the subsequent generations of particles involved in collisions, wind their way through the nucleus. The point of collision, the type of collision, the momentum of the struck nucleon, and the scattering angles for each collision are determined by statistical sampling techniques. Free-particle experimental data are used whenever cross-section data are required. Cross sections and distributions resulting from the nuclear reaction are calculated in I4C by taking the average value of many results.

6. RESTRICTIONS OR LIMITATIONS

There are no known restrictions implied by storage allocation. Target nuclei may be any element from 4He to 239Pu. Incident particle energies must be 1 MeV or greater. Incident nucleon energies must be less than 3500 MeV, and incident pion energies must be less than 2500 MeV. The results are expected to be valid only over the ranges described in section 4. The maximum possible number of incident particle histories is 999,999.

7. TYPICAL RUNNING TIME

The approximate running times on the IBM 360/91 per 1000 incident particles ranged from 0.26 minutes for a 1-GeV particle on oxygen to 3.3 minutes for the same energy particle on lead, and from 0.4 minutes for a 2.5-GeV particle on oxygen to 6.2 minutes for the same energy particle on lead. The I4C analysis with all options takes approximately 1/5 of the MECC-7 running time.

8. COMPUTER HARDWARE REQUIREMENTS

The codes were designed for the IBM 360/75/91 with standard I-O and a maximum of 6 tape units or direct access devices. Maximum core size required ~ 1020K.

9. COMPUTER SOFTWARE REQUIREMENTS

The packaged codes were run on the IBM 360/75/91 Operating System using OS-360 FORTRAN H Compiler.

I4C uses the overlay feature and was compiled with OPT = 2.

10. REFERENCES

H. W. Bertini, M. P. Guthrie, and O. W. Hermann, "Instructions for the Operation of Codes Associated with MECC-7, A Preliminary Version of an Intranuclear-Cascade Calculation for Nuclear Reactions," ORNL-4564 (May 1971).

R. L. Hahn and O. W. Hermann, "Inclusion of Fission and Charged-Particle Emission in Calculations of Nuclear Reactions; Computed Energies, Angles, and Ranges of Recoil Nuclei," ORNL-TM-3179 (April 1971).

M. P. Guthrie, "EVAP-4: Another Modification of a Code to Calculate Particle Evaporation from Excited Compound Nuclei," ORNL-TM-3119 (September 1970).

Contents of MECC Primary Output Tape, informal notes.

Contents of Nuclear Configuration Tape, informal notes (March 1969).

H. W. Bertini and M. P. Guthrie, "Results from Medium-Energy Intranuclear-Cascade Calculation," Nucl. Phys., Al69, (1971) 670-672.

H. W. Bertini, "Nonelastic Interactions of Nucleons and pi Mesons with Complex Nuclei at Energies Below 3 GeV," Phys. Rev. C, Vol. 6, No. 2 (August 1972), 631-659.

H. W. Bertini, "Intranuclear-Cascade Calculation of the Secondary Nucleon Spectra from Nucleon-Nucleus Interactions in the Energy Range 340 to 2900 MeV and Comparisons with Experiment," Phys. Rev., Vol. 188, No. 4 (December 1969) 1711-1730.

H. W. Bertini, "Low-Energy Intranuclear Cascade Calculation," Phys. Rev., Vol. 138, No. 7AB, AB2 (June 1965).

H. W. Bertini, "Low-Energy Intranuclear Cascade Calculation," Phys. Rev., Vol. 131, No. 4 (August 1963) 1801-1821.

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and one (1.2MB) DOS diskette which contains the source codes, data libraries, and sample problem input and output.

12. DATE OF ABSTRACT

February 1972; revised December 1984.