CCC-0070 CHARGE-2/C.

1. NAME OR DESIGNATION OF PROGRAM:  CHARGE-2/C.

3. DESCRIPTION OF PROBLEM OR FUNCTION

The CHARGE code computes flux spectra, dose and other response rates behind a multilayered spherical or infinite planar shield exposed to isotopic fluxes of electrons, protons and heavy charged particles. The doses, or other  responses, to electron, primary proton, heavy particle, electron bremsstrahlung, secondary proton, and secondary neutron radiations are calculated as a function of penetration into the shield; the materials of each layer may be mixtures of elements contained in the accompanying data library, or supplied by the user. The calculation  may optionally be halted before the entire shield is traversed by specifying a minimum total dose rate; the computation stops when the dose drops below this value.
The ambient electron, proton and heavy particle spectra may be specified in tabular or functional form. These incident charged particle spectra are divided into energy bands or groups, the number or spacing of which are controlled by input data. The variation of the group boundary energies and group spectra as a function of shield penetration uniquely determines charged particle dose rates and secondary particle production rates. The charged particle shielding calculation is essentially the integration of the range- energy equation which expresses the variation of particle energy wit distance travelled.

4. METHOD OF SOLUTION

The "straight-ahead" approximation is used throughout, that is the changes in particle direction of motion due  to elastic scattering are ignored. This approximation is corrected,  in the case of electrons, by applying transmission factors obtained  from Monte Carlo calculations. Inelastic scattering between protons  and the shielding material is assumed to produce two classes of secondaries
1) Cascade protons and neutrons, emitted in the same direction as    the primaries
2) Evaporation neutrons, emitted isotropically.
The transmission of secondary protons is analyzed in exactly the same way as the primaries, secondary neutron transport is calculated by a simple energy-dependent removal cross section model.
Bremsstrahlung X-rays produced by decelerating electrons are analyzed using a production model proposed by Koch and Motz (Reference 2). The response rate to X-rays is calculated by assuming an exponential attenuation through the shielding, modified by buildup factors.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Maxima of 100 shield layers and 100 energy groups are allowed.

6. TYPICAL RUNNING TIME

A 14-region, spherical geometry problem using 55 electron 40 gamma ray, 16 proton and 61 neutron groups required 3.94 minutes CP time an IBM 7090.

The test case of the program was run at NEA-DB on a PC/80486 with 66 MHz in about 30 seconds.

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS

The program includes a general purpose data input routine INPUT1, to provide flexibility in data card formats.

10. REFERENCES

- H.W. Kock, J. Motz,
  Bremmsstrahlung Cross Section Formulas and Related Data,
  Reviews of Modern Physics Vol. 31, p.920 (1959).

- W. R. Yucker, and J. R. Lilley;
  Charge Code for Space Radiation Shielding Analysis,
  DAC-62231, April 1969.
- W.R. Yucker, and J.R. Lilley:
  CHARGE Code for Space Radiation Shielding Analysis
  DAC-62231 (April 1969).
- J.R. Lilley, and W.R. Yucker:
  CHARGE, A Space Radiation Shielding Code
  SM-46335 (April 1965).
- J.R. Lilley, and W.R. Yucker:
  Coded Input Subroutine with Double Precision and Logical Input
  Capabilities
  Memorandum FORTRAN IV (November 1964).
- W.R. Yucker, and J.R. Lilley:
  Space Radiation Shielding Analysis by Program CHARGE
  Douglas Paper No. 3415 (June 1965).
- README.DOC, Informal Notes for the IBM PC, EMPC
  Gaithersburg, MD (October 13, 1990).

11. MACHINE REQUIREMENTS

Standard input and output and two scratch external storage units.

The program was implemented on a DELL 466/L PC/80486 with 66 MHz and 16 Mbytes of RAM. The disk space required by all source files is about 260 Kbytes. The filesize of the executable CHARGE.EXE is 219 Kbytes.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:

The test case was run under MS-DOS 6.2. The source program was compiled and linked using the Microsoft FORTRAN compiler Version 5.10 and the Microsoft Linker Version 5.15, respectively.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

The
input subprogram INPUT1 requires several machine dependent parameters to be stored in a COMMON block.

15. NAME AND ESTABLISHMENT OF AUTHOR

Contributed by: Radiation Safety Information Computational Center
                Oak Ridge National Laboratory
                Oak Ridge, Tennessee, U. S. A.

Developed by:   W.R. Ucker, J.R. Lilley
                Nuclear Technology and Subsystems Branch
                Mc Donnell Douglas Astronautics Company
                Western Division, USA

File name	File description	Records
CCC0070_01.001	CHARGE2/C SOURCE - FORTRAN IV	6841
CCC0070_01.002	CHARGE2/C OVERLAY CARDS	9
CCC0070_01.003	CHARGE2/C JOB CONTROL	8
CCC0070_01.004	CHARGE2/C SAMPLE PROBLEM INPUT	40
CCC0070_01.005	CHARGE2/C SAMPLE PROBLEM OUTPUT	1819

File name	File description	Records
CCC0070_03.001	CHARGE Information file	183
CCC0070_03.002	Source file # 1	1101
CCC0070_03.003	Source file # 2	1115
CCC0070_03.004	Source file # 3	936
CCC0070_03.005	Source file # 4	923
CCC0070_03.006	Source file # 5	1066
CCC0070_03.007	Source file # 6	1051
CCC0070_03.008	Source file # 7	959
CCC0070_03.009	Source file # 8	34
CCC0070_03.010	Batch "make" file (compile and link)	36
CCC0070_03.011	Auxiliary batch file to compile the sources	9
CCC0070_03.012	File with the linker directives	6
CCC0070_03.013	Linker output file	73
CCC0070_03.014	Executable file fo program CHARGE	0
CCC0070_03.015	Sample input file (test case)	39
CCC0070_03.016	Sample output file (printout results)	909
CCC0070_03.017	Half-geo sample data	39
CCC0070_03.018	Half-geo tabulated results	59
CCC0070_03.019	Half-geo, CHARGE, slab out	909
CCC0070_03.020	Half-geo, CHARGE, sphere out	909
CCC0070_03.021	Original sample problem data	44
CCC0070_03.022	DOS file-names	21