A bottle-like structure was discovered in etched tracks of fission fragment
s recorded in the gamma-ray-irradiated CR-39 track detector. The etched tra
ck has a relatively larger pit radius near the etched surface and has a sma
ller one in the deeper layer. This indicates that the supply of oxygen from
the air should control the damage formation process. (C) 2001 Elsevier Sci
ence Ltd. All rights reserved.