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INTRODUCTIONDosimetry plays an important function in the quality control of radiation processing (1) . Radiochromic ilms dosimeters based on the radiation-induced color bleaching of organic dyes have been extensively investigated for high radiation dose dosimetry (2)(3)(4)(5)(6)(7) and also in radiotherapy (8) . Clear polyvinyl chloride (PVC) ilms were investigated (9) , but there are only a few articles published about the use of PVC as a dosimeter for gamma radiation. Khan and Ahmad (10) reported that undyed PVC ilms with thickness of 1 mm were useful as gamma radiation dosimeters in the range of 1-30 kGy, and were stable for up to 30 days after irradiation. Radiation-induced color bleaching of PVC ilms containing malachite green and bromocresol purple dyes were investigated as high-dose radiation dosimeters in the dose ranges of 0-125 kGy (11) and from 0 to 50 kGy (12) , respectively. The effect of gamma radiation on the organic dye methyl red and its possible use in chemical dosimetry was investigated (13) . The useful dose range of aqueous solution of methyl red in alkaline was between 50 and 6000 Gy. Radiation-chromic ilm based on polyvinyl butyral (PVB) dyed with methyl red was investigated as a high dosimeter (14) in the range up to 150 kGy.The aim of this study was to use polyvinyl chloride PVC ilms dyed with methyl red as a high dose dosimeter. Since radio-chromic ilms used in routine dosimetry systems are usually in luenced by the environmental conditions such as irradiation time, dose rate, shelf life and post irradiation time, this study investigated the effect of these parameters on the dose range up to 150 kGy. MATERIALS AND METHODS Films preparationCommercial PVC ilms from Sabic made from resins PVC57S with thickness of 60 µm, and

Introduction It has been recently shown /1/ that, in a thin semiconductor slab (thickness much smaller than the carrier diffusion length), high current enhancement can be produced by the magnetoconcentration (MC) effect when such a sensor operates under mbre important electric or magnetic fields.In this letter, we derive general relations allowing to forecast (according to material properties) the bounds of sensitivity, the optimum slab thickness, the fields to be applied as well as the corrbsponding carrier concentrations. Moreover it is experimentally evidenced that sensitivities larger than 1500 V/T can be obtained from 100 p m thick Ge samples.