Retrospective Rn-220 Measurements by Compact Discs.

Recently, a method for retrospective ^220Rn measurements by etching alpha-tracks in compact discs (CDs) or digital video discs (DVDs) has been proposed. In that method the tracks at the front surface (with respect to the reading laser beam) of the discs are analyzed. These measurements are influenced by ^222Rn absorbed in the disc material and the signal must be corrected for ^222Rn presence. In this work we study whether the influence of ^222Rn can be eliminated if the back (labeled) side of the CDs is analyzed. Because of the coating on the back side of the disc, ^222Rn absorption is prevented and its influence on ^220Rn signal is significantly reduced. Moreover, it has been found that in most discs the signal at the back side is an order of magnitude greater than that at the front side, which significantly improves the sensitivity of the method. Thus, this work proposes a new practical approach for retrospective ^220Rn measurements of improved sensitivity and reduced ^222Rn influence. [ABSTRACT FROM AUTHOR]