GEANT-3

Abstract: A comparison of efficiency calibration of a HPGe gamma-ray spectrometer applied for non-destructive analysis of gamma-ray emitters in large volume samples of irregular shape is presented. The detector efficiency calibration was carried out during the analysis of cosmogenic radionuclides (60Co, 54Mn, 22Na and 26Al) in fragments of the Kosice meteorite. Fourteen meteorite fragments were available for the analysis with masses from 27 to 2,163 g. A reasonable agreement in the estimation of the HPGe detector efficiency was obtained using the Monte Carlo simulation GEANT 3 code, and the experimental calibration using radioactive standards mixed with iron–silica–copper powder housed in mock-ups of similar shapes as the original samples. The differences in the efficiency estimation obtained by both methods were within 10 %. It is recommended that the Monte Carlo simulation of the detector efficiency can be applied in routine analysis of gamma-ray emitters in large volume samples of regular or irregular shapes.

Abstract: A new γ-tracking method based on the Compton-scattering probability of photons in a spectrometer composed of segmented Ge detectors has been developed and evaluated with the GEANT 3 simulation code. The performance of this probabilistic method, in terms of photopeak detection efficiency and peak-to-total ratio calculated for a 4π array composed of planar detectors, is comparable with the ones obtained with the previous γ-tracking methods. Furthermore, the algorithm has been tested successfully with single detection units of other crystal shapes. A simple application is also proposed as a peak-to-total ratio enhancer for bare segmented Ge crystals in replacement of the Compton-suppression shield.

Abstract: The Monte Carlo simulation of the electron transport through air slabs is studied with four codes: PENELOPE, GEANT3, Geant4 and EGSnrc. Monoenergetic electron beams with energies 6, 12 and 18 MeV are considered to impinge on air slabs with thicknesses ranging from 10 to 100 cm. The angular and radial distributions of the transmitted electrons are used to make a comparison between the codes. Non-negligible differences are observed in the radial distributions. These differences produce worth effects in the macroscopical dose distribution absorbed in a water phantom situated behind the slabs.

Abstract: Experimental data, recently measured at CERN, on the LPM effect have been used to benchmark the description of the discrete bremsstrahlung incorporated into the GEANT 3 and GEANT 4 codes The limited accuracy of the native versions required a major revision in the framework of the original Migdal theory The results obtained with the new implementation agree quite satisfactorily with measurements The stability of the calculations when several parameters are varied has been thoroughly investigated