Differentiation of Rn-220 and Rn-222 alpha tracks on cellulose nitrate film by using alpha absorbers

The objects of this experiment is to study the differentiation of Rn-220 and Rn-222 Alpha tracks on cellulose nitrate film type CN-85 by using track-etch method with alpha absorber and to determine weight percentages of uranium and thorium in minerals which have both of uranium and thorium. Sodium hydroxide solution (NaOH-solution) with concentration of 10% weight at temperature of 60 degree celsius is used for being the suitable etchant. Aluminum-foil with thickness of 6.8 mg/cm2, which can be available, is used for being the alpha absorber. It was found that the optimum time intervals for etching Rn-222 and Rn-220 alpha tracks on cellulose nitrate film type CN-85 with aluminum absorber is 30 minutes and without aluminum absorber is 40 minutes, the ratio of Rn-222 alpha tracks density without aluminum absorber is 0.1815, the ratio of Rn-220 alpha tracks density without aluminum absorber is 0.3074. Alpha tracks from mixed gas, appeared on cellulose nitrate film with aluminum and without aluminum absorber thickness of 6.8 mg/cm2, can be differed by the ratio of alpha tracks density remainder to alpha tracks density without aluminum absorber are between 0.2468 and 0.2971. And it was found that the results of weight percentage of uranium and thorium which was analysed by track-etch method is the same order of the results from being analysed by gamma spectro metre method