New trends in luminescence dose reconstruction using natural material and personal objects.

In recent years, especially after the Chernobyl accident, techniques and methodology of luminescence dose reconstruction using fired building material have advanced to such an extent that radiation from anthropogenic sources as low as 10mGy can be resolved within two years after the event. It was demonstrated that luminescence measurements using bricks combined with Monte-Carlo simulations of photon transport for a given source geometry and distribution can provide quantities to derive doses for populations or groups of people living in contaminated areas that can be used for epidemiological studies.   In this presentation, recent approaches in luminescence dose reconstruction using un-fired building materials such as concrete and silica brick will be reviewed and the possible use of personal artefacts such as telephone chip cards or prosthetic and restorative teeth will be discussed.   The review will include the results of the joint efforts of the international team supported by the EU at the Chernobyl affected territories, areas affected due to activities of Plutonium production facilities in Southern Urals (Russia), and settlements around the Semipalatinsk nuclear bomb test sites

Radiation safety and Individual dose assessment using personal objects .

After radiation incidents , it is often found that there are not enough data or direct measurements available to describe or define the actual accident situation so as to assess the doses to which particular group of persons have been exposed. Radiation dose reconstruction is essential part of radiation risk assessment and for epidemiological studies, as well as for the correct treatment of individuals in acute cases of exposure. Furthermore, there is a growing concern in the public about accidental radiation exposures due to the ageing of the nuclear power industry, illegal dumping of nuclear waste, or terrorist activities which may result in health risks to individuals. In such events, in areas where radiation dose monitoring has not been performed, it is essential to be able to assess doses to individuals rapidly for immediate emergency medical care or for general estimation of the radiological consequences. Recent investigations have shown that certain types of SIM cards containing microchips have the potential to be used for retrospective dosimetry (Göksu 2003, Marthur 2006). It has been observed that a certain type of telephone chip-card can be used as radiation detectors for individuals exposed to external gamma doses. The radiation dose responses of more than 200 chip-cards, produced by various companies since 1990, were investigated using infrared stimulated luminescence (IRSL). The radiation dose responses of some of the chip-cards were found to be linear with radiation dose over 250 mGy to 5 Gy and stable at ambient temperature, which allows the use of such chip-cards for reconstruction of doses for individuals.  In order to determine the source of radiation induced signal, we have investigated the chip cards produced by INFINEON at various stage of production. The initial investigations show that radiation induced signal mainly come from the layer that is used for protection chip cards from the environmental effects.  In order to improve the radiation dose response and detection limits of the cards, various type of artificial phosphors are added to protecting layer of the chip cards The variation of the dose  response and the detection limit with respect to the amount and the type of the phosphor  is investigated using various luminescence techniques. Feasibility of production of such cards in industrial scale will be discussed

Luminescence dose reconstruction using personal objects and material available in the environment and public domain.

There is a growing concern in the public about accidental radiation exposures due to the ageing of the nuclear power industry, illegal dumping of nuclear waste, or terrorist activities which may increase the health risks to individuals or large numbers of public. In cases where no direct radiation monitoring data are available, luminescence dose reconstruction obtained using material from the immediate environment of population or persons can be used to validate values obtained from the numerical simulations.   In recent years, especially after the Chernobyl accident, techniques and methodology of luminescence dose reconstruction using fired building material have advanced to such an extent that radiation from anthropogenic sources as low as 10mGy can be resolved within two years after the event. It was demonstrated that luminescence measurements using bricks combined with Monte-Carlo simulations of photon transport for a given source geometry and distribution can provide quantities to derive doses for populations or groups of people living in contaminated areas that can be used for epidemiological studies.   In this presentation, recent approaches in luminescence dose reconstruction using un-fired building materials such as concrete and silica brick will be reviewed and the possible use of personal artefacts such as telephone chip cards or prosthetic and restorative teeth will be discussed

OSL from BeO ceramics: New observations from an old material

In BeO ceramics, exposed to ionizing radiation, an intense OSL signal was observed. The properties of the signal and its behavior under various experimental conditions were investigated. It was found that the OSL signal is a composite signal and exhibits strong thermal quenching. The quenching energy was estimated as similar to 0.5 eV. The excitation spectrum of the OSL signal was obtained as a broad peak in the region 420-550 nm with maximum around 435 nm. The possible correlation between the OSL signal and the peaks in the TL glow curve was also examined. It was interesting to observe that the highly light sensitive TL peak near 220 degrees C does not contribute to the OSL signal. The OSL signal was found to originate from a trap near 340 degrees C. To check the possibility of using the material for radiation dosimetry the dose response and thermal stability of the OSL signal were also investigated. The dose response was found to be guile linear up to similar to 10 Gy. The thermal activation energy of the OSL trap was determined as similar to 1.7 eV using isothermal annealing and heating rate methods thus proving the suitability for dosimetry

Phototransferred thermoluminescence from alpha-Al2O3:C using blue light emitting diodes.

Phototransferred thermoluminescence (PTTL) from alpha-Al2O3:C single crystals was studied using a blue light emitting diode (LED) for phototransfer of charges from deep traps to the main dosimetry trap. The dose response was found to be linear in the region from similar to 5 mGy to similar to 5 Gy. It was observed that the corresponding deep traps were located near 500 degrees C and heating to temperatures > 600 degrees C removes the PTTL effect induced by the light from the blue LED. The thermal activation energy of the source traps involved in the PTTL production was calculated as 3.23 eV