Weighing options for passive environmental neutron dosimetry: A comparative study of PADCs, TLDs, OSLDs, and fission track detectors

This study aims to evaluate the potential of polyallyl diglycol carbonate (PADC) detectors, coupled with ${}^6$LiF converters, for passive environmental neutron dosimetry. Their performance is compared against three other methods, fission track detectors, thermoluminescent detectors (TLDs), and optically stimulated luminescence detectors (OSLDs), to determine their viability for passive routine neutron monitoring in environmental settings.

The four detector types investigated (PADCs, fission tracks, TLDs and OSLDs) were placed in a moderator sphere and exposed to an AmBe neutron field. The measurements evaluated the dose response, measurement range, and precision of each system.

Results confirm that the advantage of the track detectors (PADC or fission track) is their gamma insensitivity: the TLD and OSLD methods require the combination of neutron-sensitive with neutron-insensitive detectors, as both are gamma-sensitive. This translated into a detection limit $H^{\ast }\left(10\right)$=6 μ Sv for PADC detectors coupled with ${}^6$LiF converters, comparable to that of fission track detectors (3 μ Sv). In contrast, the gamma-sensitive luminescence systems showed a detection limit of 10 μ Sv for the TLDs and 180 μ Sv for the OSLDs under AmBe neutron irradiations. This worsens under simulated environmental conditions, where a significant gamma contribution is expected, as demonstrated by a test where mixed gamma/neutron irradiation was used.

These results indicate the potential of the PADC coupled with a ${}^6$LiF converter system as a robust alternative to fission track detectors for passive environmental neutron dosimetry.