CCC-0160: PICA, Photon-Induced Medium-Range Nuclear Cascade Analysis by Monte-Carlo

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CCC-0160 PICA. (Abstract last modified 21-NOV-2001)

PICA, Photon-Induced Medium-Range Nuclear Cascade Analysis by Monte-Carlo

Abstract Table of Contents:

1. NAME OR DESIGNATION OF PROGRAM - PICA.

2. COMPUTER FOR WHICH PROGRAM IS DESIGNED AND OTHER MACHINE VERSION PACKAGES AVAILABLE -

To request or retrieve programs click on the one of the active versions below. A password and special authorization is required.

Explanation of the status codes.

Program-name Package-ID Status PICA CCC-0160/01 Arrived

Machines used: Package-ID Orig.Computer Test Computer CCC-0160/01 VAX under VMS

3. DESCRIPTION OF PROGRAM OR FUNCTION - PIC calculates the results of nuclear reactions caused by the collision of medium-energy photons with nuclei. The photon energy range in which the calculations are applicable is 30 < E gamma < 400 MeV. All target nuclei with mass numbers > 4 are possible. The program PIC can accommodate incident monoenergetic photons as well as thin-target bremsstrahlung spectra, thin-target bremsstrahlung difference spectra and thick-target bremsstrahlung spectra. For the last type of spectra the user must furnish the photon spectral data. PIC writes a history tape containing data on the properties of the particles (protons, neutrons, or pions) escaping from the nucleus. The data consists of the types of escaping particles and their energies and angles of emission. MECCAN utilizes the data on the PIC history tape to calculate cross sections such as the nonelastic cross section or the doubly differential cross section for energy-angle correlated distributions. EVAP then carries the nuclear reaction through an additional phase, that of evaporation, and calculates the energy spectra of particles (protons, neutrons, deuterons, tritons, 3He, and alpha particles) "boiled off" from the nucleus after the cascade has stopped, evaporation particle multiplicities, and evaporation residual nuclei (radio-chemical) cross sections.

4. METHOD OF SOLUTION - The interaction of high-energy photons with nuclei is described by using the intranuclear cascade and evaporation models. Monte Carlo methods are employed to provide a
detailed description of each interaction. The initial interaction of the photon with the nucleus is obtained from the quasi-deuteron model of Levinger, that is, photon absorption by a neutron-proton pair moving within the nucleus or from one of the four pion-nucleon states formed in the photon-nucleon interaction. The effect of secondary nucleon-nucleus and/or pion-nucleus interactions following the photon absorption is accounted for by utilizing the intranuclear-cascade concept of high-energy particle-nucleus reactions. Each particle involved in a collision is traced through the nucleus using the appropriate particle-particle cross sections until the particle escapes from the nucleus or is captured by the nucleus. In all parts of the calculation, the Fermi momentum of the struck particle, the exclusion principle, and the nonuniform density distribution are taken into account. Following the cascade phase, the nucleus is usually in a state of high excitation. This excitation energy can be dissipated through particle emission. This de-excitation is handled by the evaporation model.
NUC creates modified nuclear configuration data input for PIC. In PIC three nuclear regions are used to approximate a continuous nucleon-density distribution in the nucleus, and the radii of these regions can be changed by using NUC. PIC uses an exact sampling technique to determine the collision site and the types of particles in the reaction.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM - The range of validity of PIC is from 30 to 400 MeV for the energy of the incident photon.

6. TYPICAL RUNNING TIME - The approximate machine time to obtain reasonable statistical accuracy is 30 to 60 minutes on the IBM 360/77 computer.
Estimated running times of the packaged sample problem: CON, one minute; PIC, 2 minutes; MECCAN, one second; EVAP, 5 seconds; and NUC; one second.
The run time for PIC on a VAX 6000-420 using 40000 incident particles is 34 seconds.

7. UNUSUAL FEATURES OF THE PROGRAM -

8. RELATED AND AUXILIARY PROGRAMS -

CCC-0160/01:

CON                 Data Conversion (BCD to binary) code.
PIC                 Cascade Data Generator.
MECCAN              Interaction Data Analysis Code.
EVAP                Evaporation Data Generator.
NUC                 Nuclear Configuration Code.
FLRAN,FLOTR,FLTRN   Random Number Generators.

9. STATUS
CCC-0160/01: 21-NOV-2001 Masterfiled Arrived

10. REFERENCES  -
CCC-0160/01:
- T.A. Gabriel et al.:
  Instructions for the Operation of the Program Package PICA, An
  Intranuclear-Cascade Calculation for High-Energy (20 to 400 MeV)
  Photon-Induced Nuclear Reactions
  ORNL-4687 (September 1971).
- T.A. Gabriel and R.G. Alsmiller, Jr.:
  Photonuclear Disintegration at High (<350 MeV) Energies (Thesis)
  ORNL-TM-2481 (February 1969).
- Hugo 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
  Reprint from Phys. Rev. 188, 1711-1730 (1969).

11. MACHINE REQUIREMENTS - The codes were designed for the IBM 360/75/91 computer configuration, requiring a maximum of 3 tape units or direct access devices in addition to I-O. Storage (GO STEP) required: CON, 15K; PIC, 300K; MECCAN, 40K; EVAP, 250K: and NUC, 160K. In February 1994 the VAX package was released. It is a conversion of the February 1971 IBM version.

12. PROGRAMMING LANGUAGE(S) USED -
CCC-0160/01: FORTRAN

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED - The codes packaged are operable on the IBM 360/75/91 Operating System using OS-360 Level 18 FORTRAN H Compiler and on DEC VAX computers using VMS and the VAX Fortran compiler.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS -

15. NAME AND ESTABLISHMENT OF AUTHORS -
Contributed by:
                Radiation Shielding Information Center
                Oak Ridge National Laboratory
                Oak Ridge, Tennessee, U. S. A.

16. MATERIAL AVAILABLE -
CCC-0160/01:
README.RSI RSIC Information File
AUX1.FOR PICA Subprogram
AUX2.FOR PICA Subprogram
CROSSEC.FOR Block X-section Data
FLRAN.FOR Random Number Generator
PIC.COM VAX Command File
PIC.FOR PICA Main Module
POL1.FOR PICA Subprogram
READ_ME.PIC PICA Information File
ROUT.FOR PICA Subprogram
SAMPLE1.INP 1000 Incident Particles
SAMPLE2.INP 10000 Incident Particles
SAMPLE3.INP 40000 Incident Particles
report                   ORNL-4687 (September 1971)                 REPPT
report                   ORNL-TM-2481 (February 1969)               REPPT
paper                    Repr. from Phys. Rev. 188, 1711-1730 (1969)PAPPT

17. CATEGORIES -

- A. Cross Section and Resonance Integral Calculations
- J. Gamma Heating and Shield Design

Keywords: GAMMA RADIATION, NUCLEAR CASCADES, PHOTON INTERACTION, PHOTON TRANSPORT