GDE (GamBet Distributed-computing Extension) is a utility for the Field Precision GamBet or Xenos packages for researchers who run massive Monte Carlo simulations. The utility makes it possible to split a calculation between any number of worker computers, using all processors on each machine. GDE is compatible with any network of Windows computers.

GamBet is Monte Carlo package for simulations of X-ray and electron transport in matter. The package has several features that stand out from other Monte Carlo codes:

* 2D and 3D geometries are defined with powerful finite-element mesh generators rather than idiosyncratic solid-modeling algorithms. Advantages include the direct input of complex shapes from  SolidWorks, ProE and other packages as well as extensive visualization options. The conformal meshes provide close fits to material surfaces.

* 2D or 3D calculated electric and magnetic field solutions may be imported for detailed electron dynamics.

* GamBet incorporates the Penelope 2006 physics engine for high-accuracy interaction calculations, from GeV energies down to less than 100 eV.

* Calculations of fields, electron beam dynamics and target heating are integrated with Monte Carlo simulations in Xenos, a comprehensive software suite for X-ray source development.

* GamBet features extensive graphical and quantitative post-processing capabilities for dose distributions and particle statistics.

Field Precision introduced support in Gambet for multi-core and multiple processor computers last year. The company has taken another major step forward with GDE, which allows the division of large calculations with statistical accuracy between any number of network-connected computers.The package includes two programs, GB_SOW and GB_REAP. The operating sequence is as follows:

* GB_SOW includes all technical features of GamBet. The program may be installed on any number of computers without a license restrictions. GB_REAP is installed on a master computer with a GamBet license.

* The user sets up and tests a GamBet run using the standard programs. Then, the required input files (GamBet control script, mesh definition, electric or magnetic field files,…) are ported to the worker computers.

* GB_SOW is launched on each worker computer, either from a window or from the command line. Multiple instances of GB_SOW may run on multiprocessor machines.

* GB_SOW run produces a single binary file with a unique identifying name that contains all information from the GamBet calculation (escape particles, dose, statistics,…). The user moves output files from the worker computers to a data folder on the master computer.

* GB_REAP identifies all binary input files in the specified directory and combines them to produce GamBet output files in standard format. These files may be analyzed with GBView2, GBView3 or GenDist. Escape particles are combined in a single escape file with appropriate weightings. Statistical and dose information is averaged.

The user’s only role is to transfer files to and from the worker computers. This leaves complete flexibility for configuring the distributed network and automating file transfers. The GDE concept has several advantages:

* Calculations are independent and need not be synchronized.

* There is no overhead for parallel processing. Five quad-core computers can reduce the time to generate a required number of showers by a factor of 20.

* If one machine fails during the computation, data from the other computers is still useful.

* It is easy to improve the accuracy of a calculation by adding more showers without starting anew. The user simply creates more worker-computer files. They are added to the master folder and the total collection is recombined with GB_REAP.

* Communication between computers is solely through file transfers. Therefore, it is easy to carry out extended calculations at any locations via a company network or the Internet.

The GDE package is now available in the Field Precision catalog at http://www.fieldp.com/order.html.

About Field Precision
Field Precision LLC has created easy-to-use 2D and 3D simulation software for personal computers since 1989. Application areas include electrostatics, permanent magnets, charged-particle devices, microwave equipment, biomedical engineering and X-ray technology. The company, based in Albuquerque, New Mexico, can provide individualized training and consulting for advanced applications. For detailed information (customer lists, research projects and publications), please see http://www.fieldp.com/company.html.

Contact:

Field Precision LLC
Dr. Stanley Humphries
PO Box 13595
Albuquerque, NM 87192 U.S.A.
E mail: humphriess@fieldp.com
Telephone: +1-505-220-3975
FAX: +1-617-752-9077