EFFECT OF VACUUM, OXYGEN AND CARBON-DIOXIDE ON THE TRACK REGISTRATIONIN SR-90 AND CR-39

The molecular structure of SR-90 and CR-39 is very similar except that the average length of carbonate linkages in SR-90 is 1.6 times longer than in CR-39. However, the effect of vacuum and carbon dioxide (CO2) on the track registration of these two detectors is very different: 1 ) the sensitivity of CR-39 becomes very low in vacuum; the sensitivity of SR-90 does not go down to zero even after storage in vacuum for a long time; 2) the sensitivity of SR-90 decreases both in air and in va cuum but the original sensitivity can be restored by storing it in CO2 of 1 similar to 3 atm for several days. We also found that the sensit ization of latent tracks by oxygen (O-2) is effective only at the time of irradiation but the sensitization by CO2 is effective after irradi ation.