Marcin Latocha

AVIDOS--a software package for European accredited aviation dosimetry.

AVIDOS is a computer code used for the dose assessment of aircraft crew exposed to cosmic radiation. The code employs a multiparameter model built upon simulations of cosmic radiation exposure done using the FLUKA Monte Carlo code. AVIDOS calculates both ambient dose equivalent H*(10) and effective dose E for flight routes over the whole world at typically used altitudes and for the full range of solar activity. The dose assessment procedure using AVIDOS is accredited by the Austrian office for accreditation according to European regulations and is valid in the whole Europe. AVIDOS took part in an international comparison of different codes assessing radiation exposure of aircraft crew where a fully satisfactory agreement between codes has been found. An online version of AVIDOS with user friendly interface is accessible to public under the internet address: http://avidos.healthphysics.at.

Microdosimetric assessment of the radiation quality of a therapeutic proton beam: comparison between numerical simulation and experimental measurements

Using protons for the treatment of ocular melanoma (especially of posterior pole tumours), the radiation quality of the beam must be precisely assessed to preserve the vision and to minimise the damage to healthy tissue. The radiation quality of a therapeutic proton beam at the Centre Antoine Lacassagne in Nice (France) was measured using microdosimetric techniques, i.e. a miniaturised version of a tissue-equivalent proportional counter. Measurements were performed in a 1-µm site at different depths in a Lucite phantom. Experimental data showed a significant increase in the beam quality at the distal edge of the spread-out Bragg peak (SOBP). In this paper, the numerical simulation of the experimental setup is done with the FLUKA Monte Carlo radiation transport code. The calculated microdosimetric spectra are compared with the measured ones at different depths in tissue for a monoenergetic proton beam (E=62 MeV) and for a modulated SOBP. Numerically and experimentally predicted relative biological effectiveness values are in good agreement. The calculated frequency-averaged and dose-averaged lineal energy mean values are consistent with measured data.

Investigations on Photon Energy Response of RadFET Using Monte Carlo Simulations

We describe investigations of RadFET energy response simulated with Geant4 and FLUKA2005 Monte Carlo codes. An analysis of energy deposition is carried out for photon irradiation with energies between 35 keV and 2 MeV. The absorbed dose in the silicon dioxide layer (few hundred nanometers) is compared for both transport codes.

MATSIM: Development of a Voxel Model of the MATROSHKA Astronaut Dosimetric Phantom

The AIT Austrian Institute of Technology coordinates the project MATSIM (MATROSHKA Simulation) in collaboration with the Vienna University of Technology and the German Aerospace Center, to perform FLUKA Monte Carlo simulations of the MATROSHKA numerical phantom irradiated under reference radiation field conditions as well as for the radiation environment at the International Space Station (ISS). MATSIM is carried out as co-investigation of the ESA ELIPS projects SORD and RADIS (commonly known as MATROSHKA), an international collaboration of more than 18 research institutes and space agencies from all over the world, under the science and project lead of the German Aerospace Center. During MATSIM a computer tomography scan of the MATROSHKA phantom has been converted into a high resolution 3-dimensional voxel model. The energy imparted and absorbed dose distribution inside the model is determined for various radiation fields. The major goal of the MATSIM project is the validation of the numerical model under reference radiation conditions and further investigations under the radiation environment at ISS. In this report we compare depth dose distributions inside the phantom measured with thermoluminescence detectors (TLDs) and an ionization chamber with FLUKA Monte Carlo particle transport simulations due to 60Co photon exposure. Further reference irradiations with neutrons, protons and heavy ions are planned. The fully validated numerical model MATSIM will provide a perfect tool to assess the radiation exposure to humans during current and future space missions to ISS, Moon, Mars and beyond.

Microdosimetric GEANT4 and FLUKA Monte Carlo Simulations and Measurements of Heavy Ion Irradiation of Silicon and Tissue

We describe microdosimetric measurements and simulations with Geant4 and FLUKA Monte Carlo codes in silicon and tissue. Analyses of deposited energy in sensitive volumes of some micrometers were carried out after exposure to heavy ion radiation

Applicability of the Accelerated Switching Test Method - A Comprehensive Survey

The enhanced degradation exhibited at low dose rates by many bipolar-technology components is a major reliability issue for spacecraft electronics. As an accelerated ELDRS test method an approach has been suggested that makes use of sequenced high dose rate and low dose rate exposures - the so called accelerated switching test method. In this paper we describe the results of an application of the accelerated switching test method to the LM158 operational amplifier and LM339 comparator. Degradations of a comprehensive set of device parameters are measured. Prediction curves of the low dose rate response are estimated. The quality of the prediction curves is discussed by comparing them with reference data obtained from continuous low dose rate testing.

Cosmic radiation assessment at ESA's space weather portal with AVIDOS

We present an overview of cosmic radiation assessment done by measurements and Monte Carlo modelling. Further, we discuss effects by sporadic solar energetic particles and introduce a nowcast model for radiation exposure at flight altitudes.

Comprehensive radiation characterization of digital isolators

We investigate TID radiation response and SEE susceptibility of six different digital isolators by exposing them to Co-60 gammas with 300 krad(Si) and various proton and heavy ion fields with LET of up to 60 MeV·mg^−1·cm². The type with the least radiation degradation was also exposed to 10 MeV electrons and 14 MeV neutrons.

TID and SEGR Radiation Characterisation of European COTS Power MOSFETs with Respect to Space Application Electronics

We investigated TID radiation response and SEGR susceptibility of two COTS power MOSFETs by exposing them to Co-60 photons with 100 krad(Si) and various heavy ion fields of LET between 18.5 and 60 MeV mg-1cm-2.

MATSIM: A voxel model for the astronaut dosimetric phantom MATROSHKA

The AIT Austrian Institute of Technology coordinated the project MATSIM (MATROSHKA Simulation) in collaboration with the Vienna University of Technology and the German Aerospace Center, to perform FLUKA Monte Carlo simulations of the MATROSHKA numerical phantom for the radiation environment at the International Space Station (ISS). MATSIM, a voxel model of the MATROSHKA phantom was developed during the project MATSIM Phase-A. In this paper we describe results of the project Phase-B of MATSIM, Monte Carlo simulation of the absorbed dose and the neutron fluence assessed inside the whole model phantom. The simulations are verified by reference measurements using thermoluminescence dosimeters, an ionisation chamber and a tissue equivalent proportional counter (TEPC). Further investigations are carried out for ISS cosmic radiation conditions. MATSIM provides a comprehensive risk assessment of radiation hazard to humans working in space onboard the ISS, for missions to the Moon, Mars and beyond, as well as for terrestrial mixed radiation fields comprising ionizing high-energy particle radiation.