Correlation between Conductivity and X-ray Colorability in Pure and Doped KCL

According to the mass action law and electrical neutrality, Ca doped alkali-halide crystals should be more difficult to color with X-rays than pure crystals.This is contrary to what experiments show.It was then decided to investigate the correlation between the amount of divalent impurities (Ca) contained in “pure” and doped KC1 crystals, and the number of F centers produced with X-ray.Conductivity measurements were done to determine the Ca++ content of the crystals. It was found that at 78° K the number of F centers produced after some time of irradiation is insensitive to the amount of impurities for the impure crystals. At 273° K the number of F centers produced after relatively long irradiation time was roughly proportional to the concentration of Ca to the 1/5 power, for the impure crystals.At 273° K for long irradiation, the absorption band at223 mu was found to be proportional to the absorption at the F band, independent of the amount of impurities. Advisor: E. Pearlstei