| Etching time (min) | Track density (ρno/mm2) | ||
| Time of exposure to alpha source | |||
| (10 sec) | (20 sec) | (30 sec) | |
| 30 | 637 | 1003 | 1846 |
| 60 | 644 | 1050 | 2288 |
| 90 | 720 | 1304 | 2208 |
| 120 | 732 | 1367 | 2211 |
| 150 | 823 | 1300 | 2122 |
| 180 | 681 | 1254 | 2034 |
| 210 | 670 | 1216 | 2018 |
| 240 | 654 | 1212 | 1979 |
| Average | 695.1 | 1213.2 | 2163.2 |
| Max | 823 | 1367 | 2288 |