**RSICC CODE PACKAGE CCC-713**

**1. NAME AND TITLE**

PENELOPE-MPI: Code System to Perform Monte Carlo Simulation of Electron Gamma-Ray Showers in Arbitrary Materials,

based on PENELOPE-2001. PENELOPE is available from the NEADB and RSICC

**AUXILIARY PROGRAM**

PENGEOM2: Generation of random electron-photon showers in material systems consisting of homogeneous bodies limited by quadric surfaces.

GVIEW2D and GVIEW3D: Display geometry on the computer screen.

**2. CONTRIBUTORS**

Universitat de Barcelona and Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya, Barcelona, Spain; Universidad Nacional de Cordoba, Argentina; Indiana University, Indianapolis, Indiana.

**3. CODING LANGUAGE AND COMPUTER**

Fortran 90, MPI; IBM-SP (C00713IBMSP00).

**4. NATURE OF PROBLEM SOLVED**

PENELOPE performs Monte Carlo simulation of electron-photon showers in arbitrary materials. Initially, it was devised to simulate the PENetration and Energy LOss of Positrons and Electrons in matter; photons were introduced later. The adopted scattering model gives a reliable description of radiation transport in the energy range from a few hundred eV to about 1GeV. PENELOPE generates random electron-photon showers in complex material structures consisting of any number of distinct homogeneous regions (bodies) with different compositions. The Penelope Forum list archives and other information can be accessed at http://www.nea.fr/lists/penelope.html.

PENELOPE-MPI extends capabilities of PENELOPE-2001 (RSICC C00682MNYCP02; NEA-1525/05) by providing for usage of MPI type parallel drivers and extends the original version's ability to read different types of input data sets such as voxel. The motivation is to increase efficiency of Monte Carlo simulations for medical applications. The physics of the calculations have not been changed, and the original description of PENELOPE-2001 (which follows) is still valid.

PENELOPE-2001 contains substantial changes and improvements to the previous versions 1996 and 2000. As for the physics, the model for electron/positron elastic scattering has been revised. Bremsstrahlung emission is now simulated using partial-wave data instead of analytical approximate formulae. Photoelectric absorption in K and L-shells is described from the corresponding partial cross sections. Fluorescence radiation from vacancies in K and L-shells is followed. Refinements were also introduced in electron/positron transport mechanics, mostly to account for energy dependence of the mean free paths for hard events. Simulation routines were re-programmed in a more structured way, and new example MAIN programs were written with a more flexible input and expanded output.

**5. METHOD OF SOLUTION**

The Monte Carlo method is used. A sufficiently large number of particle histories is simulated, and relevant quantities are obtained as averages.

**6. RESTRICTIONS OR LIMITATIONS**

Note that PENELOPE does not work for elements with atomic number Z>92. Electron and positron kinetic energies must be in the range from 100 eV to 1 GeV. Plural or multiple scattering conditions must be fulfilled, i.e. the number of both elastic and inelastic interactions in the material must be larger than about 10. Photon energies must be in the range from 100 eV (or the M-shell absorption edge, whichever is largest) to 1 GeV. Photo-nuclear reactions are disregarded.

**7. TYPICAL RUNNING TIME**

The running time largely depends on the number of histories to be simulated, the kind of incident particle and its initial energy and the considered geometry.

**8. COMPUTER HARDWARE REQUIREMENTS**

Penelope-MPI runs on IBM SP workstations.

**9. COMPUTER SOFTWARE REQUIREMENTS**

Penelope-MPI runs under the AIX operating system on IBM SP workstations and can be run in serial mode on IBM. Fortran 90 and C compilers and MPI are required to build executables for the parallel version. The code was tested at RSICC on an IBM SP3 with mpxlf90 and mpcc compilers.

GVIEW2D, GVIEW3D, and GVIEWC executables from Penelope-2001 are included to display geometry on the computer screen. They run on personal computers under Microsoft Windows 9x, NT or Windows2000 and are simple and effective tools for debugging geometry definition files.

**10. REFERENCES**

**a: Included in document:**

"ReadmeIU.txt" information file (October 2002).

F. Salvat, J.M. Fernandez-Varea E. Costa, and J. Sempau, "PENELOPE - A Code System for Monte Carlo Simulation of Electron and Photon Transport," Workshop Proceedings, Issy-les-Moulineaux, France, ISBN:92-64-18475-9 (November 2001).

**b. Background information:**

R. B. Cruise, V. P. Moskvin, R. L. Sheppard, " Parallelization of PENELOPE Monte Carlo," Indiana University, to be presented at ANS M&C 2003, Gatlinburg, Tennessee (April 6-10, 2003).

F. Salvat and J.M. Fernandez-Varea, "Semiempirical cross sections for the simulation of
the energy loss of electrons and positrons in matter." *Nucl. Instrum. and Meth. B63* (1992) 255-269.

J.M. Fernandez-Varea, R. Mayol, J. Baro and F. Salvat, "On the theory and simulation of
multiple elastic scattering of electrons." *Nucl. Instrum. and Meth. B73* (1993) 447-473.

J.M. Fernandez-Varea, R. Mayol and F. Salvat, "Cross sections for elastic scattering of
fast electrons and positron by atoms." *Nucl. Instrum. and Meth. B82* (1993) 39-45.

T.M. Jenkins, W.R. Nelson and A. Rindi, eds., Monte Carlo Transport of Electrons and Photons (Plenum, New York, 1988). See, in particular, chapter 17.

M.J. Berger and S.M. Seltzer, several chapters in Monte Carlo Transport of Electrons and Photons, eds. T.M. Jenkins, W.R. Nelson and A. Rindi (Plenum, New York, 1988).

J.A. Halbleib, R.P. Kensek, T.A. Mehlhorn, G.D. Valdez, S.M. Seltzer and M.J. Berger, Sandia National Laboratories Report SAND91-1634 (1992).

W.R. Nelson, H. Hirayama and D.W.O. Rogers, Stanford Linear Accelerator Center Report SLAC-265 (1985).

R. Brun, F. Bruyant, M. Maire, A.C. McPherson and P. Zanarini, CERN Report DD/EE/84{1 (1986).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document in 10.a and a CD which contains source files, test case input files, data files and documentation written in a GNU compressed Unix tar file.

**12. DATE OF ABSTRACT**

October 2002.

** KEYWORDS:** MONTE CARLO; BREMSSTRAHLUNG; HIGH ENERGY; GAMMA-RAY;
POSITRON; WORKSTATION