1. NAME AND TITLE OF DATA LIBRARY

PHOTX: Photon Interaction Cross Section Library.

2. NAME AND TITLE OF DATA RETRIEVAL PROGRAMS

XREAD: Program for Retrieval and Display of Photon Cross Sections (PC version).

READX: Program for Retrieval and Display of Photon Cross Sections (minicomputer version).

3. CONTRIBUTORS

National Institute of Standards and Technology, Gaithersburg, Maryland.

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

4. HISTORICAL BACKGROUND AND INFORMATION

The National Bureau of Standards, through its Office of Standard Reference Data, has long maintained and published compilations of measured and evaluated photon cross sections. This compilation of PHOTX Version 2, released on personal computer media, represents best values as determined in 1987.

5. APPLICATION OF THE DATA

Partial interaction coefficients and total attenuation coefficients are useful in any radiation transport or other radiation analysis application.

6. SOURCE AND SCOPE OF DATA

The data from the National Bureau of Standards include interaction cross sections and attenuation coefficients for 100 elements covering the energy range 1 keV to 100 GeV. The reactions considered are coherent and incoherent scattering, photoelectric absorption, and pair production. A separate table gives the photo-effect cross section for each electron shell.

7. DISCUSSION OF THE DATA RETRIEVAL PROGRAMS

XREAD is a program for the IBM PC and compatibles for the retrieval and display of the partial interaction coefficients and total attenuation coefficients for any selected element. The input is interactive. The user specifies the element by atomic number, and a formatted data file with column headings is produced. Output cross sections are in units of barns per atom, and attenuation coefficients are in units of cm²/g. Note: the total attenuation coefficient without coherent scattering includes bound Compton scattering.

The XREAD program is written in Fortran 77 and was tested at RSIC using the Ryan-McFarland Version 2.42 compiler. NBS provided both source and executable programs, compiled by a Ryan-McFarland compiler, on the distribution diskettes. A math co-processor is necessary.

The mainframe-minicomputer version, which was tested on both Data General and VAX computers, is distributed on tape with all the data in one formatted file. Two Fortran 77 retrieval programs, tested on the VAX and Data General families of computers, are provided. RANDOM will produce a direct-access file from the basic data file; and READX will retrieve data for particular elements interactively, producing output similar to that of XREAD. The total attenuation coefficient, without coherent and based on free-electron Compton scattering, is also listed in the READX output.

8. DATA FORMAT AND COMPUTER

ASCII Fortran source, binary data files and executable program on 360 K DS/DD diskettes (3) or 1.2 MB HD diskette (1); IBM PC (A). Fortran sources and data file on DOS diskette; Data General MV and VAX computers (B).

9. TYPICAL RUNNING TIME

The programs are interactive.

10. REFERENCES

D. K. Trubey, M. J. Berger and J. H. Hubbell, "Photon Cross Sections for ENDF/B-VI," American Nuclear Society topical meeting, Advances in Nuclear Engineering Computation and Radiation Shielding, Santa Fe, New Mexico (April 9-13, 1989).

D. K. Trubey, Informal Notes, RSIC (December 1988).

11. CONTENTS OF LIBRARY

Included are the referenced documents and either three 5.25-in. DS/DD diskettes or one 1.2 MB diskette containing the data files, Fortran source file, executable file, and documentation file for the PC version (A); or Fortran source files and data files on tape for the mainframe-minicomputer version (B).

12. DATE OF ABSTRACT

May 1989.