1. NAME AND TITLE

STAR CODES: Code System for Calculating Stopping-Power and Range Tables for Electrons, Protons, and Helium Ions.

2. CONTRIBUTOR

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

3. CODING LANGUAGE AND COMPUTER/OPERATING SYSTEM

Fortran 77, IBM PC.

4. NATURE OF PROBLEM SOLVED

The "STAR CODES", ESTAR, PSTAR, and ASTAR, calculate stopping-power and range tables for electrons, protons, and helium ions (alphas), according to methods described in ICRU Reports 37 and 49.

5. METHOD OF SOLUTION

Collision stopping powers are calculated from the theory of Bethe (1930, 1932), with a density-effect correction evaluated according to Sternheimer (1952, 1982). The stopping-power formula contains an important parameter, the mean excitation energy (I-value), which characterizes the stopping properties of a material. The codes provide output for electrons in any stopping material (279 provided) and for protons and helium ions in 74 materials. The calculations include the 1)Collision stopping power, 2)Radiative stopping power (electrons only), 3)Nuclear stopping power (protons and helium ions), 4)Total stopping power, 5)CSDA range, 6)Projected range (protons and helium ions), 7)Density effect parameter (electrons), 8)Radiation yield (electrons), and 9)Detour factor (protons and helium ions). Standard energy grids and files of elements w/ionization-excitation information are included with lookup table capabilities.

6. RESTRICTIONS OR LIMITATIONS

The minimum energies used in the calculations are at 1 keV (protons and helium ions) and 10 keV (electrons), and the maximum are 1 GeV. The standard energy grids are set at 81 for electrons, equally spaced (logrithmically), 133 for protons, and 122 for helium ions. The lower energy electron calculations (< 10 keV) have up to 5-10% errors and are considered too fallable.

7. TYPICAL RUNNING TIME

The running time is dependent on the type of hardware (PC XT vs. PC 486) used, but generally a calculation takes a few seconds.

8. COMPUTER HARDWARE REQUIREMENTS

Any IBM PC or compatible using a parallel printer (Epson, IBM, or HP laserjet) would be adequate. A math co-processor is necessary. The entire software package with examples will require 2.7 Mbytes of space on the harddrive.

9. COMPUTER SOFTWARE REQUIREMENTS

DOS 2.0 or higher, with 640 kB RAM are requirements. The Lahey Fortran compiler was used to create the executables included in the package.

10. REFERENCES

A. Included in Package:

Berger, M. J., "ESTAR, PSTAR, and ASTAR: Computer Programs for Calculating Stopping-Power and Range Tables for Electrons, Protons, and Helium Ions" NISTIR 4999 (1992).

B. Background Information:

ICRU Report 37, "Stopping Powers for Electrons and Positrons" (1984).

ICRU Report 49, "Stopping Powers and Ranges for Protons and Alpha Particles" (1993).

Sternheimer, R. M. "The density effect for the ionization loss in various materials," Phys. Rev. 88, 851 (1952).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and 1 DS/HD (1.2 MB) diskette which contain the Fortran 77 source files, compiled Lahey Fortran executables, with input data files, a packing list, and a README.1ST help file. README.1ST describes the installation and operation of the codes. All executables are compressed and contained in self-extracting (est.exe,pst.exe, and ast.exe) files using LHarc's SFX 2.125 compression utility.

12. DATE OF ABSTRACT

April 1993.