Borosilicate glass media for neutron sensing

Abstract

This work using a borosilicate glass medium seeks to detect photoneutrons generated by a medical linear accelerator. The studies involved an Elekta Infiniti accelerator located in the Oncology Centre, Medical City, Riyadh, the neutrons resulting from interactions at above-threshold therapeutic photon energies. The borosilicate detectors were produced from microscope glass slides of nominal thickness 1.0 mm, the latter made into square segments of area 0.6 × 0.6 cm2, a size capable of being accommodated within the planchette of the thermoluminescent (TLD) Reader (Harshaw 600). With some 4% boron in the coverslip glass and the abundance of 10B being 19.8%, thermalised neutrons 10B(n,α)7Li interactions offer a cross-section that can achieve a value as large as 3837 b. Apart from interactions in boron, of additional note is that 2H(γ,n)1H and 9Be(γ,n)8Be are two further photoneutron reactions, giving rise to particularly low threshold energies at 2.226 and 1.666 MeV, respectively. The presence of natural carbon in the present borosilicate samples has been measured to be 1.3%. Accordingly, with the abundance of 13C in natural carbon being 1.109% this would appear to be of very little interest herein. Moreover, compositional measurements made on the borosilicate coverslip glass indicates 9.40 Na. The induced activity in the glass falls to some 25% 30 h post-irradiation, a delay time beyond which readout can subsequently be conducted.