[en] The scaling of electron implantation profiles with incident energies over the range 0.5-4 keV at normal angle of incidence are presented using the Monte Carlo scheme to generate stopping profiles in semi-infinite Al and Au. A simple scaling relationship which reduced the stopping profiles onto a single universal curve for that studied material is proposed with only two fitting parameters instead of four parameters previously reported in the literature. This permits accurate profiles for low energy electrons in metals to be obtained in a simple way that does not require any recourse to Monte Carlo calculations in the generation of electron stopping profiles

[en] Backscattering (Bcs) coefficients for low-energy positrons (∼100 eV) from elemental solids have been simulated using an analytic approach. The model is based on the use of the transport cross-sections (TCSs) and the stopping power calculated from partial wave methods and the best-fit stopping power data of Ashley, respectively. The new result is an extension of recent calculations in the medium energy range. Comparisons, when possible, with experimental and Monte-Carlo (MC) simulation data have been made

[en] Electron and positron backscattering coefficients are analytically calculated for a number of selected atomic targets in the energy range 1-10 keV and for incident angles between 0 deg. and 80 deg. The dependence of the backscattering coefficient on the material, on the projectile primary energy and on the incidence angle has been examined and discussed. Our results are found to be in better agreement with experiment than earlier Monte Carlo simulations

[en] We report one case of multilocular cyst of the kidney in one year and three months female infant who underwent echography, computed tomography and MRI before surgery. MR image accurately reflect the morphology of the tumor: the capsule is hypointense on T1-weighted images, the septa show moderate enhancement with intraveinous contrast. Varied intensities from fluid in the visualized locules presumably represent different concentration of proteins. MR imaging features are highly suggestive but non pathognomonic of the disease. Positive diagnosis always require histology. (authors). 7 refs., 7 figs

[en] The general purpose Monte Carlo code PENELOPE is used to calculate microdosimetric quantities including dose-weighted lineal energy spectra, which can be used to predict relative biological effect (RBE), for binary radiation therapies that utilise the photoabsorption of X-ray of high-Z materials. Spectra are calculated for Gd homogenously distributed at a concentration of 10 mg/ml in water and irradiated by 70 keV monoenergetic photons, around 20 keV above the k-edge of Gd (50.239 keV), which has been shown to give optimal dose enhancement, and for a metallic Gd surface in close proximity (within 2 μm) to a sensitive component of the nucleosome, modelled as a sphere of water of 1 μm diameter, for 60 and 70 keV monoenergetic X-rays. X-ray interactions with homogenously distributed Gd lead to a greater population of high lineal energy electrons than in liquid water, probably due to the creation of short range Auger electrons and photoelectrons, whereas interactions with Gd outside of the sensitive volume are longer ranged increasing the population of low lineal energy electrons. The data does not support increased therapeutic advantage through increased RBE in the case of Gd bearing contrast systems where little cellular absorption of Gd occurs. Homogenously distributed Gd leads to higher lineal energies than pure water, probably due to the creation of short range, high LET Auger and photoelectrons, whereas photoelectrons that originate in Gd that are outside the sensitive volume tend to have relatively higher energies and long ranges increasing the population of low LET electrons

[en] In order to simulate the energy deposited of low energy electrons in a solid state silicon detector, a detailed Monte Carlo technique has been applied to describe electron scattering processes from silicon in the keV and sub-keV electron energy range. However, the precision on the energy deposited depends strongly on the accuracy of the energy of the total backscattered electrons. Thus, accurate models are needed to simulate the energy spectra of primary, secondary and Auger electron yields. In the present Letter, we show that the inclusion of ionizations, excitations, secondary electron generation, relaxations and Auger emissions provide a better description of the experimental measurements.

[en] The Karlsruhe Tritium Neutrino experiment (KATRIN) derives the mass of the electron anti-neutrino with a sensitivity of 0.2 eV/c² (90% C.L.) in a model-independent way from the measured energy spectrum of tritium β-decay electrons. The focal plane detector (FPD) is a large silicon PIN diode detecting the electrons transmitted by a large MAC-E spectrometer. To model the detector response to low-energy electrons, a full Monte Carlo simulation was developed and benchmarked.

[en] The Karlsruhe Tritium Neutrino (KATRIN) experiment will determine the mass of the electron neutrino with a sensitivity of 0.2 eV (90% CL) via a measurement of the β-spectrum of gaseous tritium near its endpoint of E₀ = 18.57 keV. An ultra-low background of about b = 10 mHz is among the requirements on reaching this sensitivity. In the KATRIN main beam line, two spectrometers of MAC-E filter type are used in tandem configuration. This setup, however, produces a Penning trap, which could lead to increased background. We have performed test measurements showing that the filter energy of the pre-spectrometer can be reduced by several keV in order to diminish this trap. These measurements were analyzed with the help of a complex computer simulation, modeling multiple electron reflections from both the detector and the photoelectric electron source used in our test setup. (paper)

[en] Semiconductor detectors in general have a dead layer at their surfaces that is either a result of natural or induced passivation, or is formed during the process of making a contact. Charged particles passing through this region produce ionization that is incompletely collected and recorded, which leads to departures from the ideal in both energy deposition and resolution. The silicon p–i–n diode used in the KATRIN neutrino-mass experiment has such a dead layer. We have constructed a detailed Monte Carlo model for the passage of electrons from vacuum into a silicon detector, and compared the measured energy spectra to the predicted ones for a range of energies from 12 to 20 keV. The comparison provides experimental evidence that a substantial fraction of the ionization produced in the “dead” layer evidently escapes by diffusion, with 46% being collected in the depletion zone and the balance being neutralized at the contact or by bulk recombination. The most elementary model of a thinner dead layer from which no charge is collected is strongly disfavored

[en] The focal-plane detector system for the KArlsruhe TRItium Neutrino (KATRIN) experiment consists of a multi-pixel silicon p-i-n-diode array, custom readout electronics, two superconducting solenoid magnets, an ultra high-vacuum system, a high-vacuum system, calibration and monitoring devices, a scintillating veto, and a custom data-acquisition system. It is designed to detect the low-energy electrons selected by the KATRIN main spectrometer. We describe the system and summarize its performance after its final installation