Determination of gamma dose and thermal neutron fluence in BNCT beams from the TLD-700 glow curve shape

State of the art on nuclear heating measurement methods and expected improvements in zero power research reactors

“…Since the photon sensitivity of 6 Li and 7 Li-enriched TLDs are equivalent, and assuming that their isotopic composition is accurately known, differential measurements with these two types of TLDs could allow estimating both the neutron and photon doses in a mixed field. Researchers from INFN 2 recently proposed a method for determining the photon dose and the thermal neutron fluence in a BNCT n-g field from the glow curves (GCs) of LiF TLDs [11]. This method, illustrated in Figure 3, relies on the deconvolution of the signal of a TLD-700 ( 7 Li-enriched, low neutron sensitivity) irradiated in mixed field, using the GCs obtained from the same TLD irradiated in a pure g field (photon calibration), and with thermal neutrons (neutron calibration).…”

“…As shown in Figure 3, the neutron component of the TLD-700 response (pink triangles) and the TLD-600 GC (green squares) are in rather good agreement. Li ∼ 0.01%) irradiated in mixed n-g field (blue line), compared with the glow curve of a TLD-600 ( 6 Li/ 7 Li ∼ 95.6%) irradiated with thermal neutrons (green squares, secondary axis) [11].…”

“…10 Vulcan Experimental Nuclear System (SCK•CEN, Mol, Belgium). 11 Maquette de Surgénérateur de Cadarache (CEA Cadarache, France).…”

“…The direct neutron dose D n is then calculated in the reactor geometry. As discussed in Section 2.2, the use of 7 Li and 6 Li-enriched TLDs calibrated in both g and neutron fields would permit to experimentally determine the neutron contribution to the total measured dose using the INFN method [11] (see Sect. 2.2), that would avoid resorting to literature data whose uncertainties are usually pretty large (see Tab.…”

“…Finally, the determination of integrated doses implies a processing of raw measurements thanks to calibration and cavity correction factors, as well as neutron dose correction, which is currently deduced from literature data with pretty high uncertainties (up to 100% at 1s). Starting from that current methodology, one can identify some optimization opportunities revolving around the following three aspects: ü -Need to experimentally determine the neutron contribution to the total measured dose, by using the discrimination method described in Section 2.2 [11,59].…”