CALIBRATION OF SILICON DETECTORS LIULIN AND AIRDOS USING COSMIC RAYS AND TIMEPIX FOR USE AT FLIGHT ALTITUDES.

Silicon detectors such as Liulin and AIRDOS are used for cosmic radiation measurements onboard aircraft. These measurements can be used for the verification of computer programs assessing aircraft crew radiation exposure. Recently performed intercomparison flights showed large variances of absorbed doses among individual detectors and significant differences between results of silicon detectors and computer programs. In order to explain for these differences, we have developed energy calibration method that can be performed on short flights. The method is based on cross-calibration of Liulin and AIRDOS deposited energy spectra with deposited energy spectra measured by Timepix which has superior detection properties in terms of energy resolution and the detection threshold. Moreover, the portion of dose which is omitted due to low sensitivity for low-energy deposits was calculated. The resulting absorbed dose rates at two intercomparison flights show significantly improved variation of results and better agreement with modelled absorbed dose rates.

VERTICAL DOSIMETRIC MEASUREMENT OF ELECTRIC DISCHARGE INDUCED AT LIGHTNING IMPULSE VOLTAGE GENERATOR.

This paper deals with the measurement of ionising radiation emitted in the vertical field of electric discharge generated between the tip and the grounded plate electrode. The generator set-up was for 400 consecutive negative discharges with voltage amplitude 0.9 MV, waveform shape 1.2/50 $\mu $s, discharge energy 80 kJ and electrodes 1 m apart. Thermoluminescent, passive detectors were used to avoid electromagnetic interference from the discharge. The detectors were placed at the electrodes and three vertical positions 1 m from the discharge axis. This work extends a previous study focused on dosimetry in the plane parallel to the ground. This experiment confirmed the presence of a photon/electron component at the electrode tip and 0.5 m vertical position at a distance of 1 m from the discharge axis. In addition, the presence of neutrons was found for new positions in the vertical axis and the ground electrode.