Experimental observations of changes in thermoluminescence sensitivity of a
polymineral fine-grain sample are reported. A repeat alpha regeneration ex
periment, involving multiple cycles of heating and alpha irradiation reveal
ed a sensitivity decrease. It was further investigated whether this effect
is caused by irradiation or heating. Our experiments show that repeated the
rmal treatments result in an increase in thermoluminescence (TL) sensitivit
y. This is in contrast to the effect of cycles of alpha irradiation which l
ed to a decrease in TL sensitivity. This decrease was found to be dependent
on the alpha irradiation history. (C) 2000 Elsevier Science Ltd. All right
s reserved.