Neutron spectroscopy with bubble detectors - potential and limitations

Bubble detectors have proved to be valuable devices for quick and sensitive neutron dosimetry. Now there are bubble detectors available with different thresholds ranging from 10 keV to 10 MeV (spectrometer sets). Using these sets it is possible to get some information about the neutron spectrum but they are not a complete substitute for a conventional neutron spectrometer. With this device it is only possible to get information about trends of neutron spectra. Nevertheless this is of great interest because the neutron dose equivalent depends strongly on the neutron energy. The response of many neutron survey monitors (e.g. rem counters) overestimate the dose equivalent for neutrons with energies less than 500 keV and their response falls off rapidly for neutrons with energies above 5 MeV. We have performed measurements with the spectrometer sets at the INT facilities (300 keV D2-Accelerator, SODERN Genie 26, isotopic neutron sources). The results are compared to other neutron spectrom eters with higher energy resolution. Additionally, we made measurements behind different shielding materials and compared the results with shielding calculations.