Two significant limitations of the paired LiF thermoluminescent (TL) technique for the determination of γ dose in mixed n-γ radiation fields are discussed. These are; (i) the likelihood of large variations in the behaviour of the TL sensitivity as a function of neutron energy from dosimeter batch to dosimeter batch due to minute variations in the dosimeter preparation and (2) the likelihood of large absorbed dose in TLD-600 due to thermal neutrons (compared to the fast neutron or γ dose) resulting in the necessity of a third independent experimental dose or fluence measurement of the thermal neutrons. It is estimated that for radiation fields where φth φf > 0.05, even the angular distribution of the thermal neutrons at the point of interest must be determined to enable adequately accurate calculation of the thermal neutron selfshielding factor in TLD-600.
ASJC Scopus subject areas
- Medicine (all)