Introduction on MULASSIS and GEMAT analysis tools

The Geant4-based Microdosimetry Analysis Tool (GEMAT) and Multi-Layered Shielding Simulation Software (MULASSIS) are application programs for the study of SEP radiation effects based on the Geant4 radiation transport simulation toolkit. GEMAT studies microdosimetry effects of space radiation on microelectronics/micro-sensors and MULASSIS uses one-dimensional multi-layered planar or spherical shield geometries to assess radiation shielding performance, particularly for the evaluation of secondary radiation. Concerning the secondary particle production, GEANT4 follows the following principles:

The GEMAT and MULASSIS tools function as run managers for Geant4, controlling the initialization of the appropriate classes to define the geometry and the particle sources, track the physical interaction processes (e.g. electromagnetic and nuclear interactions) and to commence execution of the radiation transport simulation. For the execution of both functions the following parameters need to be defined:

Table 1. List of Geant4 physics scenarios applicable for solar protons:
scenarios 1-8 are treated by MULASSIS and scenario 4 and 8 are treated by GEMAT.

Table 2. Types of analysis provided in GEMAT and MULASSIS.
Fluence of particle entering each SV and record their energy spectrum Fluence spectra at the boundaries between the different layers
Pulse-height spectrum of energy deposition in each SV Non-ionizing energy loss (NIEL) analysis at the boundaries of layers
Path length distribution in units of events .bin-1 per incident particle Energy deposition/Total ionizing dose in any layer
Coincidence rates between the SVs Pulse-height spectrum (PHS) of energy deposition at any layer


In SEPEM both tools can be applied by users with no programming experience and very little knowledge of Geant4 itself. SEPEM users only have to define the data table, the particle species, the device geometry and the device material(s).


[1] Geant4:
[2] GEMAT:

Last modified: 21.05.2010 by IS