Simple experimental method for alpha particle range determination in lead iodide films

An experimental method for determining the range of alpha particles in films based on I-V-s analysis has been suggested. The range of 5.5 MeV alpha particles in PbI2 films determined by this technique is 30 +/- 5 mu m, and this value is in agreement with the value calculated by SRIM (the stopping and range of ions in matter), r=24 mu m in PbI2. More than 100 I-V-s of PbI2 films with different thicknesses and quality have been analyzed, and the influence of alpha particle radiation on PbI2 I-V-s curves has been studied. Developed analytical methods (dependence of current density on electric field and conception of surface defects) were used, and the method limitations are discussed. It was shown that I-V-s demonstrate the tendency to obey Ohm's law under alpha radiation. On the other hand, dark conductivity of the lead iodide films shows a typical impure character that can lead to an overestimation of the alpha particles' range in PbI2 films. After films were exposed to alpha radiation, the dark resistivity and I-V shape of some films improved. Also, a weak decrease of the charge carrier concentration, due to a decrease of the "surface defect" concentration ("surface refining"), was registered after successive measurements of I-V-s. (C) 2007 American Institute of Physics.