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**1. NAME AND TITLE**

PTRAN: Proton Monte Carlo Transport Program for the PC.

**2. CONTRIBUTOR**

National Institute of Standards (NIST), Gaithersburg, Maryland.

**3. CODING LANGUAGE AND COMPUTER**

Fortran 77; PC 386.

**4. NATURE OF PROBLEM SOLVED**

PTRAN, Version 1.1, uses a Monte Carlo program to calculate the transport of proton beams through extended media. The PTRAN code uses 50 to 250 MeV beams through water phantoms. Multiple scattering and Coulomb interaction energy loss mechanisms are taken into account along with nonelastic nuclear interactions. PTRAN calculates deposition of energy as a function of depth and radial distance from the beam, energy spectra of the primary protons as function of depth. Both 1 and 3 dimensional calculations are available.

**5. METHOD OF SOLUTION**

The PTRAN system uses several cross-section preparation programs and two main codes, PTRAN3D and PTRAN1D. The heart of the calculations is the Monte Carlo model which is based on the condensed-random-walk method (BERGER, 1963), and takes into account the following types of events occurring in successive short track segments: (a) energy-loss straggling in Coulomb collisions with atomic electrons, (b) multiple-scattering deflections due to elastic scattering by atoms, and (c) energy losses in nonelastic nuclear reactions. Data preparation programs the facilitate the sampling of energy losses (VAVILOV, 1957) and angular deflections (MOLIERE, 1948). The initial proton stopping powers and ranges in water use PSTAR (NISTIR 4999, RSIC PSR-330).

**6. RESTRICTIONS OR LIMITATIONS**

The codes PTRAN1D(PTRAN1DX & PTRAN1DY) and PTRAN3D are memory intensive, and need 7.5 MBytes of RAM to execute. The support codes, data conversion and preparation codes (PTSUM, PARAM4, MPREP, VPREP, MCON, VCON) need 4 MBytes RAM. The code PTRAN3D ran an example that took 56 minutes on a 80486/87 50 MHz machine. The math co-processor is mandatory with the executables supplied which used the Lahey Fortran F77L3 compiler and Phar Lap DOS Extender/Linker.

**7. TYPICAL RUNNING TIME**

Using the 80486/87 50 MHz PC, the PTRAN3D took 56 minutes of run time, the PTRAN1D took 35 minutes. On a 80386/87 33 MHz PC, all the data preparation programs were run using less than a minute, including the interactive requests for parameter input.

**8. COMPUTER HARDWARE REQUIREMENTS**

The executable codes were compiled and linked using Lahey F77L3 /EM32 version 5.0 which requires a 80386 w/80387 math co-processor or better. The PTRAN1D and PTRAN3D required 7.5 Mbytes of RAM to run while the other executables need less than 3.5 Mbytes RAM. No special graphics monitor or printer is necessary. The total set of codes with executables, input files, and output files will occupy at least 15 Mbytes of hard disk space.

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9. COMPUTER SOFTWARE REQUIREMENTS**

MS-DOS version 3.3 or higher is required. The memory requirements of several Mbytes of RAM require DOS Extender software or equivalent to access the memory above 640 kByte. The Lahey F77L3/EM32 version 5.01 with Phar Lap's DOS Extender was used to compile and link the executables included in the distribution diskettes. When running these executable programs there needs to be access on the hard drive to a error file F77L3.EER supplied by Lahey and included in the diskettes.

**10. REFERENCE**

Included in Package:

M. J. Berger, "Proton Monte Carlo Transport Program PTRAN," NISTIR 5113 (January 1993).

Background Information:

M. J. Abramowitz and I. A. Stegun, "Handbook of Mathematical Functions," National Bureau of Standards Applied Mathematics Series 55 (1964).

M. J. Berger, "Monte Carlo Calculation of the Penetration and Diffusion of Charged Particles," Methods in Computational Physics, Vol. 1, p. 135, Academic Press, N.Y. (1963).

M. J. Berger, "ESTAR, PSTAR, and ASTAR: Computer Codes for Calculating Stopping Power and Range Tables for Electrons, Protons, and Helium Ions," National Institute of Standards and Technology Report, NISTIR 4999, (1992) (RSIC PSR-330).

H. A. Bethe, "Moliere's Theory of Multiple Scattering," Phys. Rev. 89, 1256 (1953).

D. Kahaner, C. Moler, S. Nash, "Numerical Methods and Software," Prentice-Hall (1989).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and 3 DS/HD 5.25-in. (1.2 MB) diskettes which include source, executable, and data files in DOS compressed, self extracting format using software from PKware. See the README.1ST computer file for an updated listing of the contents of each self-extracting file, and an introductory help file on the distribution diskette and F77L3.EER a run-time error listing file needed by the Lahey compiled programs.

**12. DATE OF ABSTRACT**

May 1993.

**KEYWORDS:** COMPLEX GEOMETRY; MONTE CARLO; PROTON;

MICROCOMPUTER