DLC-0174 ZZ-XCOM.

ZZ-XCOM.

FORMAT: The input file FDAT produces the binary file UDAT (direct access unformatted). This file is then used by the program XCOM1 to retrieve and display the photon cross-sections and attenuation coefficients.

NUMBER OF GROUPS:Photon cross-section data files (partial interaction coefficients and total attenuation coefficients) for 100 elements in the energy range 1 KeV to 100 GeV.

MATERIALS:H, He, Li, Be, B, C, N, O, F, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Po, At, Rn, Fr, Ra, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm.

TEMPERATURES:

ORIGIN: Several sources. It is based on an experimental data base consisting of 21000 data points from 512 literature sources. Same sources as DLC-136/PHOTX.

WEIGHTING SPECTRUM: The weighting factors, i.e., the fractions by weights of the atomic constituents, are calculated from the chemical formula entered by the user.

The National Institute of Standards and Technology, through its Office of Standard Reference Data, has long maintained and published compilations of measured and evaluated photon cross sections. This compilation of XCOM Version 1.2, released on personal computer media, represents best values as  determined in 1987. XCOM1 (Version 1.3, copyright 1991) is similar to XCOM but uses the direct-access unformatted database file UDAT.

The data from the National Institute of Standards and Technology are in binary files 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. The XCOM data are derived from the same source  as DLC-0136/ZZ-PHOTX.

The programs are interactive.

DLC-0174/01: The package was installed and the auxiliary programs were executed in the following systems:

1. PC DELL Optiplex GXM 5100 - Pentium processor @ 99 MHz base memory 640 Kbye and extended memory 32 Mbyte

2. DEC 3000 Model 300X - Alpha AXP Architec.

Workstation In both systems, the retrieval and display of the photon data takes a few tenths of a second in both the PC and the DEC-Alpha workstation.

ZZ-XCOM is a program for the IBM PC and compatibles for the retrieval and display of the partial interaction coefficients and total attenuation coefficients for elements, compounds, and mixtures. The input is interactive. The user specifies the element or compound chemical symbol or provides weight fractions for each constituent specified by atomic number. A standard energy grid can be used for the output, or the user can modify the energy grid. Two kinds of output are produced: labeled tables for printing or arrays for input to other programs. The output can be in units of cm2/g or barns per atom.

Note: the total attenuation coefficient without coherent scattering includes bound Compton scattering.

• S.L. Kalla, C. Leubner and J.H. Hubbell:
  Further Results on Generalized Elliptic-Type Integrals. Reprint from "Applicable Analysis", 25(1987) 269-274

• J.H. Hubbell:
  Photon Attenuation Coefficients and Cross Section Data 100 Ev to 100 GeV. Current Status and Prospects. Proceedings of the 2nd International Symposium on Radiation Physics, Penang (1983) 15-27

The memory requirement for XCOM1.2 is 256 Kbytes. The operating system assumed is PC-DOS or MS-DOS, version 2.0 or later. A math co-processor is desirable but not necessary.

The XCOM1.2 program is written in Fortran 77 and was tested at RSIC using the Ryan-McFarland Version 2.42 compiler. Both the source program (eight files) and the executable program provided by NIST, compiled by a Ryan-McFarland compiler, are on the distribution media.

The XCOM1.3 subdirectory includes a less system-dependent Fortran source and ASCII data files. This program can be compiled on many systems and was tested at RSIC on an IBM RS/6000 under aix 3.2.5 using the f77 command with the xlf 3.2.2.3 compiler. It was also tested on a Northgate 486 using the Lahey F77 Vers. 5.1 compiler under DOS 6.0 with 8 MB memory and on a P5-120 MHz with 16 MB memory under Windows 95. The PC executables RSIC created when testing are included in this directory. XTRANS must be run to convert the ASCII data to binary before executing ZZ-XCOM.

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

Developed by:   National Institute of Standards and Technology
                Gaithersburg, Maryland, U.S.A.