Martin Šefl1 ,2, Václav Štěpán3,2, Kateřina Pachnerová Brabcová4,2, Iva Ambrožová2, Ondřej Ploc2, Mathieu Karamitros3, Sébastien Incerti3, Marie Davídková1 ,2 1 Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic. 2 Department of Radiation Dosimetry, Nuclear Physics Institute of the ASCR, Prague, Czech Republic. 3 Université Bordeaux, CNRS/IN2P3, Centre d’Etudes Nucléaires de Bordeaux Gradignan, CENBG, Gradignan, France. 4 Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden. Calculation of solid-state track-etched detectors response in 290 MeV/u and 400 MeV/u C-1 2 ion beams using Geant4 Abstract Solid-state track-etched detectors (TED) can be applied as linear energy transfer (LET) spectrometers of charged particles. Monte Carlo simulations are helpful to identify particle types in the LET spectra and estimate their importance outside the detection range of TEDs. We have applied the Geant4 Monte Carlo simulation toolkit version 9.6p01 [1 ,2] to reproduce the beamline geometry [3] and experimental setup used for the measurements of LET spectra of 290 MeV/u and 400 MeV/u carbon ion beams at Heavy Ion Medical Accelerator in Chiba, Japan. The spectra were measured with track-etched detector TD1 (Japan Fukuvi Chemical Industry Co. Ltd), which is under our evaluation conditions sensitive to charged particles of LET between 9.46 and 500 keV/µm. The dose and LET spectra of the beam attenuated by several thicknesses of PMMA filters were calculated in water and compared with the experimental data. Calculations and measurements [4, 5] were in a good agreement within the sensitivity range of the detectors. Track etched detectors Heavily ionizing particles cause damage in the track etched detector (TED) material―a latent track. The latent track can be developed by etching in NaOH (70°C). The etched tracks are visible under an optical microscope (Figure 1 ). TED can work as spectrometers of LET. TED were exposed with C-1 2 beam 290 and 400 MeV/u in HIMAC-BIO room in Japan. TEDs do not detect particles with LET below the certain threshold (9.46 keV/µm for the TD1 by Japan Fukuvi Chemical Industry Co. Ltd). Methods The geometry description of the HIMAC-BIO beamline and the experimental set-up was based on on-site measurements. The upper view of the geometry can be seen in the Figures 2a, b, c. The beam was attenuated with the given combination of the Binary PMMA filters. The particles were scored inside a 0.1 mm thick layer. TED were calibrated to unrestricted LET in water, hence water was assigned to the detector volume TD1 . The LET of each particle was calculated as the fraction of the total energy loss and the total track length in the scoring volume. Electrons are not included in the LET spectra, since TED do not detect electrons. We used Geant4 version 9.6p01 , physics list FTF_BIC 2.0 and production threshold was set to 5 µm. Results The spectra of unrestricted LET in water behind PMMA shielding of various thickness were calculated using 2x1 05 primary C-1 2 ions and depth dose distributions in water phantom were calculated with 1 05 primary particles. Acknowledgements The work was supported by the Ministry of Education, Youth and Sports of the Czech Republic project n. LG1 3031 . The access to computing and storage facilities owned by parties and projects contributing to the National Grid Infrastructure MetaCentrum, provided under the programme “Projects of Large Infrastructure for Research, Development, and Innovations” (LM201 0005) is highly appreciated. Thanks belongs to the Czech Technical University and Nuclear Physics Institute of the Academy of Sciences of the Czech Republic for funding the attendance at this workshop. We thank to HIMAC staff for data from the reference measurements. References [1 ] J. Allison et al. IEEE Transactions on Nuclear Science, 53 (2006) 270–278. [2] S. Agostinelli et al. Nuclear Instruments and Methods in P