CCC-0064 LPSC.

1. NAME OR DESIGNATION OF PROGRAM:  LPSC: Lewis Proton Shielding Code.

3. DESCRIPTION OF PROBLEM OR FUNCTION

LPSC calculates proton and neutron flux and energy spectra behind a multilayered infinite slab  of shielding, irradiated normally with a given energy spectrum of protons. The fluxes are used to calculate doses in water or tissue.
The total dose, in rads or rems, includes contributions from primary and secondary protons and from secondary neutrons.

4. METHOD OF SOLUTION

Primary protons are assumed to travel in straight lines through the shield, losing energy by ionizing inter-  actions at a rate given by tabulated range-energy data. Inelastic collisions remove protons from the beam and generate the following secondaries:
i) Cascade protons and neutrons, assumed to be emitted in the same      direction as the primaries
ii) Evaporation neutrons, emitted isotropically, with a fission     energy spectrum.
Cascade protons and neutrons are propagated through the system in the same way as the primaries, and they produce higher generations of secondary particles. Evaporation neutrons are assumed to produce  no secondaries, their flux at the inside of the shield is computed by the numerical evaluation of the appropriate integral expression.
Elastic scattering between cascade neutrons and hydrogen is assumed to reduce the neutron energy without changing its direction. The recoil proton is assigned the energy lost by the neutron, and is assumed to be omitted in the same direction.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

There is a maximum of 20 layers of shielding, and a maximum of 10 angles, used in the angular part of the numerical integration to compute the evaporation neutron flux.

6. TYPICAL RUNNING TIME

For a sample problem 0.01 hours for TAPFIX and 0.09 hours for LPSC itself were required on an IBM 7090.

7. UNUSUAL FEATURES OF THE PROGRAM

The program includes relevant data for the following materials: hydrogen, beryllium, carbon, nitrogen,  oxygen, aluminium, titanium, iron, tungsten, lead, uranium, water, polyethylene.

8. RELATED AND AUXILIARY PROGRAMS

Program TAPFIX was written to read  the data, mentioned in section 7, from cards and to create a data tape to be input to LPSC.

- R.I. Hildebrand and H.E. Renkel
"The Lewis Proton Shielding Code"
NASA TM X-52166 (1966)
- H.W. Bertini
"Low Energy Intranuclear Cascade Calculations"
Phys.Rev. 131, 1801 (1963)

11. MACHINE REQUIREMENTS

Standard input and output, and one additional logical input unit, 32768 bytes of core and a maximum of five external storage units are required.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  Standard.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHOR

R.I. Hildebrand, H.E. Renkel
Lewis Research Center
Cleveland, Ohio, USA

File name	File description	Records
CCC0064_01.001	TAPFIX SOURCE - FORTRAN IV	76
CCC0064_01.002	TAPFIX SAMPLE PROBLEM DATA	894
CCC0064_01.003	LPSC SOURCE - FORTRAN IV	1550
CCC0064_01.004	LPSC SAMPLE PROBLEM DATA	21
CCC0064_01.005	LPSC SAMPLE PROBLEM OUTPUT	755