1. NAME AND TITLE
MICAP: A Monte Carlo Code System for Analysis of Ionization Chamber Responses.
RDNDF: Reads and processes ENDF/B-formatted cross section files.
MICRO: Manipulates the microscopic cross section data sets.
MACRO: Creates macroscopic cross section data sets.
NEUTRON: Neutron transport module.
RECOMB: Calculates the saturation effects correction data.
HEAVY: Recoil heavy ions and charged particle transport module.
PECSP: Generates photon and electron cross section and material data.
PHOTPREP: Generates photon source input for the PHOTON module.
PHOTON: Photon and electron transport module.
ENDF/B-V data pre-processed through the RESEND5-LINEAR/SIGMA1 programs so that all
cross section data are linearly interpolable over the entire energy range have been included in the
package for the following nuclides: hydrogen, carbon, nitrogen, oxygen, fluorine, aluminum, argon
and calcium. Pair production data is also included for input to PESCP.
Oak Ridge National Laboratory, Oak Ridge, Tennessee.
3. CODING LANGUAGE AND COMPUTER
Fortran IV and Assembler Language; IBM 3033 (P00261I303300).
4. NATURE OF PROBLEM SOLVED
MICAP has been developed to determine the response of a gas-filled cavity ionization chamber or
other detector type (plastic scintillator, calorimeter) in a mixed neutron and photon radiation
environment. In particular, MICAP determines the neutron, photon, and total response of the detector
system. The applicability of MICAP encompasses all aspects of mixed field dosimetry analysis
including detector design, pre-experimental planning and post-experimental analysis. MICAP is a
modular code system developed to be general with respect to problem applicability. The transport
modules utilize combinatorial geometry to accurately model the source/detector geometry and also use
continuous energy and angle cross section and material data to represent the materials for a particular
5. METHOD OF SOLUTION
The calculational scheme used in MICAP follows individual radiation particles incident on the
detector wall material. The incident neutrons produce photons and heavy charged particles, and both
primary and secondary photons produce electrons and positrons. As these charged particles enter or
are produced in the detector material, they lose energy and produce ion pairs until their energy is
completely dissipated or until they escape the detector. Ion recombination effects are included along
the path of each charged particle rather than applied as an integral correction to the final result. The
neutron response is determined from the energy deposition resulting from the transport of the charged
particles and recoil heavy ions produced via the neutron interactions with the detector materials. The
photon response is determined from the transport of both the primary photon radiation incident on the
detector and also the secondary photons produced via the neutron interactions. MICAP not only yields
the energy deposition by particle type and total energy deposited, but also the particular type reaction,
i.e. elastic scattering, inelastic scattering, (n,p),(n,alpha),etc., which produced the particle depositing
the energy. Physics to handle ENDF/B-V partial cross section data have been incorporated in the
neutron transport module to account for all processes which may contribute to the output signal. The
transport modules utilize continuous angular distribution and secondary energy distribution data when
selecting the emergent direction and energy of a particle. Furthermore, reactions are treated as
discrete and are allowed to occur with any of the constituent nuclides comprising a mixture. Finally,
MICAP incorporates a combinatorial geometry package and input cross section processors to eliminate
restrictions in the modeling capability of the code system with respect to geometry, physical processes,
nuclear data and sources.
6. RESTRICTIONS OR LIMITATIONS
Present dimensions limit the number of media to 10 in PHOTON. Dimensions restrict the number
of media to 15 and the number of nuclei per medium to 11 in the RECOMB module. The RDNDF
module is currently configured to process one nuclide at a time.
7. TYPICAL RUNNING TIME
Running time is problem dependent. The sample problem requires no more than 25 seconds in any
8. COMPUTER HARDWARE REQUIREMENTS
MICAP is operable on the IBM 3033 computer. Core storage required varies among modules.
Typical problems require approximately 1000 K bytes of memory.
9. COMPUTER SOFTWARE REQUIREMENTS
The Fortran H-Extended Enhanced compiler was used under MVS.
a. Included in documentation:
J. O. Johnson and T. A. Gabriel, "A User's Guide to MICAP: A Monte Carlo Ionization Chamber
Analysis Package," ORNL/TM-10340 (January 1988).
b. Background information:
J. O. Johnson and T. A. Gabriel, "Development and Evaluation of a Monte Carlo Code System
for Analysis of Ionization Chamber Responses," ORNL/TM-10196 (July 1987).
11. CONTENTS OF CODE PACKAGE
Included are the referenced document and one DC6150 cartridge tape in TAR format, with source
programs, sample input and output.
12. DATE OF ABSTRACT
KEYWORDS: DETECTOR RESPONSE; GAMMA-RAY CROSS SECTION PROCESSING; MONTE CARLO; NEUTRON CROSS SECTION PROCESSING; SCINTILLATION DETECTOR