The response of a tissue equivalent proportional counter (TEPC) has been simulated with the Monte Carlo transport code FLUKA. The absorbed dose distribution of lineal energy y has been determined for several monoenergetic photon and neutron sources. The agreement between the calculated results and the measurements carried out with different well-known sources is well demonstrated. Work is in progress in order to evaluate the response of the instrument in the cosmic ray environment.

The European-Commission-supported project DOSMAX (Dosimetry of Aircrew Exposure to Radiation During Solar Maximum) was aimed at measuring aircrew exposure to cosmic radiation on-board the aircraft during solar maximum. During a dedicated international comparison mission (Co-ordinated Access to Aircraft for Transnational Environmental Research; CAATER) different measurement techniques have been compared by six European institutes (Results of the CAATER Mission, DOSMAX Meeting, Dublin, June 2004). In this paper, we present the tissue-equivalent proportional counter (TEPC) measurements carried out by ARC Seibersdorf research (ARCS), Austria, and Institut de Radioprotection et de Sûreté Nucléaire (IRSN), France, together with a comparison with simulation results under the same conditions. The whole flight campaign consists of four different in-flight investigations performed at two different geographical positions at 12.2 km (FL 400) and 9.8 km (FL 320). One location was chosen above Rome (42 degrees North, 12 degrees East), Italy, for high cut-off rigidity (6.4 GV) and the second above Aalborg (57 degrees North, 10 degrees East), Denmark, for low cut-off rigidity (1.8 GV). The TEPC measurements are presented in terms of absorbed dose and ambient dose equivalent as well as microdosimetric spectra as a function of lineal energy. For the same conditions of the CAATER flights the response of the TEPC has also been simulated by using the Monte Carlo Transport Code FLUKA (version 2003). The results from simulations are compared with measurements and they show a reasonable agreement.

In times of climate change, the reduction in embodied greenhouse gas emissions is a premise for sustainable concrete infrastructure. As Portland cement clinker is mainly responsible for the high CO2 emissions of concrete, its reduction is necessary. In order to be sustainable, the concrete must meet processing, mechanical and durability properties while taking cost aspects into account. The paper presents (i) the “micro-filler/eco-filler concept” for achieving a clinker reduced, optimised binder and (ii) a performance-based approach to put sustainable “Eco-concrete” into practice. Clinker is substituted by locally available inert fillers by at least two different particle size fractions and supplementary cementitious materials. The method is based on particle packing optimisation, reduction in water demand and optimisation of the mix ratio of the binder blend, which allows the performance requirements to be met. The new Eco-concretes deliver the desired performance in terms of processability, strength and durability (water penetration, frost, carbonation and chloride resistance) while lowering the environmental impact in comparison to standard concrete. One of the new mixes was used for a small animal passage tunnel. The direct comparison of the developed Eco-concrete and standard concrete showed a 24% reduction in CO2, while achieving satisfactory workability, stripping strength and durability performance.

The response of a tissue equivalent proportional counter (TEPC) in a mixed radiation field with a neutron energy distribution similar to the radiation field at commercial flight altitudes has been studied. The measurements have been done at the CERN-EU High-Energy Reference Field (CERF) facility where a well-characterised radiation field is available for intercomparison. The TEPC instrument used by the ARC Seibersdorf Research is filled with pure propane gas at low pressure and can be used to determine the lineal energy distribution of the energy deposition in a mass of gas equivalent to a 2 microm diameter volume of unit density tissue, of similar size to the nuclei of biological cells. The linearity of the detector response was checked both in term of dose and dose rate. The effect of dead-time has been corrected. The influence of the detector exposure location and orientation in the radiation field on the dose distribution was also studied as a function of the total dose. The microdosimetric distribution of the absorbed dose as a function of the lineal energy has been obtained and compared with the same distribution simulated with the FLUKA Monte Carlo transport code. The dose equivalent was calculated by folding this distribution with the quality factor as a function of linear energy transfer. The comparison between the measured and simulated distributions show that they are in good agreement. As a result of this study the detector is well characterised, thanks also to the numerical simulations the instrument response is well understood, and it's currently being used onboard the aircrafts to evaluate the dose to aircraft crew caused by cosmic radiation.

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