The thermal neutron responses in the range 1010 to 2*1012 n cm-2 and the gamma -ray sensitivities of common thermoluminescent materials (CaSO4:Dy, CaSO4:Tm, CaF2:Dy, CaF2:Mn, Li2B4O7:Mn, LiF (TLD-700, TLD-100, TLD-600), Mg2SiO4:Tb and BeO) have been studied in detail and the results compared with those published elsewhere.

A thermoluminescent dosimeter badge has been designed for use in a countrywide personnel monitoring program. The badge is based on CaS0,:Dy phosphorembedded Teflon TLD discs. A set of metal filters has been incorporated in the badge to compensate for the energy-dependent response of the CaSOs:Dy phosphor at low photon energies. An open-window region has been provided for estimating beta dose. The response of the badge to beta and gamma radiation, its energy and angular dependence, and its reusability in a number of repeated cycles of measurements are discussed.

The effect of UV (253.7 nm) bleaching at room temperature (= 25 "C) as well as at 300 "C on the intensity of peak 10 (425 "C), and on radiation induced sensitization of peak 5 (210 "C) and peak 7 (270 "C) is studied in LiF (TLD-100) as a function of UV bleaching time. Intense W irradiation at 300 "C for 1 h almost completely removes the RTL peak 10 (reduced by about a factor of 200) and the sensitization factor (8/8,,) of peak 7 reduces from 35 to 1.1. The decay of peak 10 and the decay of sensitization of peak 7 appear to follow each other very well. On the basis of results presented here it is confirmed that peak 10 is responsible for the sensitization of peak 7. The conversion of peak 10-centres to peak 7-centres is suggested as one of the possible mechanisms for the sensitization of peak 7 during the test y-irradiation of the sensitized sample.Der EinfluB einer W (253,7 nm)-Tilgung bei Zimmertemperatur (e 25 "C) und bei 300 "C auf die Intensitit des Maximum 10 (425 "C) und auf die strahlungsinduzierte Sensibilisierung des Maximum 5 (210 "C) und Maximum 7 (270 "C) wird in LiF (TLD-100) in Abhiingigkeit von der W-Tilgungsdauer untersucht. Eine intensive UV-Bestrahlung bei 300 "C von 1 h beseitigt fast vollstiindig den RTL-Peak 10 (reduziert urn etwa den Faktor 200) und der Sensibilisierungsfaktor (S/S,) von Maximum 7 verringert sich von 35 auf 1,l. Die Abnahme von Maximum 10 und die Abnahme der Sensibilisierung von Maximum 7 scheinen gut aufeinander zu folgen. Auf der Grundlage der vorgelegten Ergebnisse wird bestitigt, daB Maximum 10 fur die Sensibilisierung des Maximum 7 verantwortlich ist. Es wird angenommen, daB die Umwandlung der Maximum-10-Zentren in Maximum-7-Zentren als einer der moglichen Mechanismen fur die Sensibilisierung des Maximum 7 wiihrend der y-Bestrahlung der sensibilisierten Probe darstellt.

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In LiF:Mg, Ti dosimeters, gamma -irradiation at low temperature (77K) reduces the TL intensities of peaks 7 (260 degrees C) and 10 (450 degrees C) drastically whereas the TL intensity of peak 5 (200 degrees C) remains nearly the same as that after irradiation at room temperature (RT). This implies that during irradiation, interstitial migration is involved in the formation of traps giving rise to peaks 7 and 10. The generic nature of peaks 7 (Z2) and 10 (Z3) traps and their (Z2 to or from Z3) trap conversion are further demonstrated. Since diffusion processes are inhibited, F and Z centres are not formed efficiently in LiF dosimeters irradiated at 77K. Studies on supralinearity, sensitisation, thermal history, optical absorption, optical bleaching, phototransfer and LET dependence following irradiation at RT and at 77K imply that four different processes (competing nonluminescent centre, track interaction during read-out, Z centre and mobile interstitial) are operating simultaneously to varying extents during the trapping/luminescent stage of different TL glow peaks. The photon emission mechanisms of these peaks are discussed. The claim that supralinearity of peak 5 is related to Z3 production is disproved. Further studies on Z centre identification in LiF:Mg, Ti are indicated.

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The thermal neutron response and gamma -ray sensitivity of CaSO4:Dy as a function of Dy concentration were studied in detail. CaSO4 with 0.2% Dy has maximum gamma -ray sensitivity. The thermal neutron response of CaSO4:Dy increases rapidly with concentration beyond 0.1% Dy. CaSO4:0.05% Dy (or Tm) has high gamma -ray sensitivity coupled with low thermal neutron response and hence is useful for gamma -ray dosimetry in mixed fields. A mixture of LiF TLD-100 and TLD-700 was arrived at for rem equivalent dosimetric purposes in a mixed field consisting of thermal and intermediate energy neutrons and gamma -rays. Mixtures of CaSO4:Dy with various lithium based materials were also selected for the same purpose. The thermal neutron response and glow peak temperature of CaSO4:(Dy, 6Li) were studied as a function of 6Li concentration.