RSICC Home Page ITS6


1.         NAME AND TITLE

ITS 6.0: Integrated TIGER Series of Coupled Electron/Photon Monte Carlo Transport Codes System.


XGEN: Continuous-energy cross-section generation program.

CEPXS: Multigroup cross-section generation program.

2.         CONTRIBUTOR

Sandia National Laboratories, Albuquerque, New Mexico.


Fortran 95; Shell Scripts; PC Windows, Linux, MAC (C00792PCX8600).


The Integrated Tiger Series (ITS) is a powerful and user-friendly software package permitting state-of-the-art Monte Carlo solution of linear time-independent coupled electron/photon radiation transport problems, with or without the presence of macroscopic electric and magnetic fields of arbitrary spatial dependence. The goal has been to simultaneously maximize operational simplicity and physical accuracy. Through a set of preprocessor directives, the user selects one of the many ITS codes. The ease with which the makefile system is applied combines with an input scheme based on order-independent descriptive keywords that makes maximum use of defaults and internal error checking to provide experimentalists and theorists alike with a method for the routine but rigorous solution of sophisticated radiation transport problems. Physical rigor is provided by employing accurate cross sections, sampling distributions, and physical models for describing the production and transport of the electron/photon cascade from 1.0 GeV down to 1.0 keV. The availability of source code permits the more sophisticated user to tailor the codes to specific applications and to extend the capabilities of the codes to more complex applications. Version 6, the latest version of ITS, contains (1) improvements to the ITS 5.0 codes, and (2) conversion to Fortran 95. The general user friendliness of the software has been enhanced through memory allocation to reduce the need for users to modify and recompile the code.


The TIGER series of time-independent coupled electron/photon Monte Carlo transport codes is a group of multimaterial and multidimensional codes designed to provide a state-of-the-art description of the production and transport of the electron/photon cascade. The continuous-energy ITS codes are based primarily on the ETRAN model, which combines microscopic photon transport with a macroscopic random walk for electron transport. The multigroup ITS codes are based primarily on the MORSE model, with a modification by Sloan to model electron elastic scattering, both of which preserve the angular moments of scattering with discrete scattering angle models. Emphasis is on simplicity of application without sacrificing the rigor or sophistication of the physical model.


New Capabilities Since 5.0

·         Array allocation is the foremost feature added to ITS since version 5.0. The requirement that users modify array-size parameters and recompile for different calculations has been nearly eliminated. Instead, ITS now reads the input file to dynamically allocate almost all arrays to the required sizes. While most arrays are dynamically allocated based on the contents of the input file, some array sizes are still hardwired. In a few cases, keywords have been made available to allow the user to increase these array sizes without code modification and recompilation. For example, the CODEZONES-PER-PATH, TRAJECTORY-POINTS, OVERLAP-MAX-OUTPUT, and PLOTS-OVAL-RESOLUTION keywords serve this purpose.


·         Along with automating the memory allocation functions, the user has been provided with keywords that assist in controlling memory usage. The new keywords NO-DEPOSITIONOUTPUT and NO-SZDEPOSITION-OUTPUT can be used to suppress printing deposition in the output file, while the new keywords NO-DEPOSITION and NO-DETAILED-DEPOSITION can be used to limit the tallies and memory allocated for deposition. To limit the memory required for tallying photon flux and escape, line radiation can be tallied with continuum radiation using the new LINE-TALLY-WITH-CONTINUUM and ANNIHILATION-LINETALLY- WITH-CONTINUUM keywords.


·         Electrons can now be transported in CAD geometries in the continuous-energy codes.


·         The user can now run the PCODES without uniform shell biasing enabled and uniform shell biasing is no longer the default behavior of the PCODES. Instead this can be activated with the BIAS-SHELL sub-keyword under the BIASING keyword. With this change it is now recommend that the PCODES be used for almost all calculations.


·         Doppler broadening for incoherent photon interactions is now supported for all materials, i.e. compounds as well as single element materials.


·         Support for radiation below 1 keV has been added. For now, this is restricted to photons sampled below 1 keV and only absorption is modeled. Photons may be sampled below 1 keV as source particles. Some physical processes can produce photons below 1 keV, such as bremsstrahlung production and incoherent photon scattering. No scattering of radiation below 1 keV is included. See the BELOW-1KEV keyword for more details. The new capability for attenuation of source photons below 1 keV requires the Livermore evaluated data library for photons, which is not distributed with ITS. It is available for download from the IAEA website at ITS uses the EPDL97 in ENDF/B-VI format. This file should be located in the XGEN distribution at .../Code/XSdata/epdl97.all.


·         The efficiency of large combinatorial geometries can be improved using features to read and write the geometry connectivity array. See the READ-CONNECTIVITY and DUMPCONNECTIVITY keywords for more details.


·         A more efficient parallel algorithm has been implemented along with more robust parallel error handling.  The improved efficiency is most significant for calculations performed on thousands of processors. Dynamic load balancing is now accessed as a keyword, DYNAMIC-MPI, rather than as a preprocessor definition.


·         The field codes have changed considerably as the MCODES have been integrated into the standard codes. There are now more options for selection of fields without code modification. See the EBFIELDS keyword for more details. See the following section on changes to input requirements also.


·         The PLOTS capability is now an integral part of the CYLTRAN and ACCEPT codes. PLOTS is invoked only with a keyword, without requiring a unique preprocessor definition. Plotting is now amenable to use with spreadsheets and plotting programs like TecplotR.


·         Material thickness information can be extracted to a separate file while performing a RAYTRACE calculation. See the AREAL-DENSITY-OUTPUT keyword for more information.


·         ITS now performs the proper normalization for volumetric sources in adjoint.


·         Electron escape and emission data can be output to a PFF formatted file. (The user must supply the pff libraries.) See the PFF-FILE keyword for more details.


·         Deposition data can be written to a separate file in a simple list format with a variety of formatting options. These are options to the FINITE-ELEMENT-FORMAT keyword.


·         ITS now allows other files to be “included” in an input deck with the INCLUDE-FILE keyword. This allows a user to eliminate duplicate information between input decks. E.g., one file with the combinatorial geometry data used for multiple runs with differing output data requirements.


·         A diff utility capable of suppressing differences in numerical data below specified tolerances is now included with ITS. This can simplify the task of performing installation testing of ITS and XGEN on a new platform.


None stated.


Running time varies greatly depending on problem parameters.  The sample problems were on the order of 10s of seconds.


ITS is operable on Windows, Linux, and MacOS systems.


Fortran compilers are required to compile the source code.  No executables are included.  The source was compiled and tested on Windows 7, RedHat Enterprise Linux, and MacOS 10.7.2 operating systems.

10.       REFERENCES

a. included documentation:

Brian C. Franke, Ronald P. Kensek, Thomas W. Laub, and Martin J. Crawford, “ITS Version 6: The Integrated TIGER Series of Coupled Electron/Photon Monte Carlo Transport Code Revision 4,” SAND2008-3331 (July 2009).


Included in the package are the referenced document, source files and sample problems with outputs transmitted on CD ROM in zip format.


January 1985; revised August 1987, October 1987, February 1988, September 1990, February 1991, April 1992, June 1992, July 1992, March 1993, January 1994, February 1994, March 1994, November 1994, November 1997, November 1999, October 2002, November 2004, November 2012.