Special introduction for this issue

Abstract

The 10B/11B isotopic ratio and the atomic composition of boron carbide, an important non-metallic ceramic, have been determined non-destructively by the particle induced γ-ray emission (PIGE) and elastic backscattering spectrometry (EBS) techniques with proton beams. The analysis has been performed on powder as well as sintered ceramics containing boron in natural or 10B enriched composition. The PIGE technique, performed at a 4.0–4.2 MeV proton energy, utilizes the 10B(p,αγ)7Be, 10B(p,p′γ)10B and 11B(p, p′γ)11B nuclear reactions for (a) the isotopic analysis of boron and (b) the determination of total boron, and the 13C(p,p′γ)13C nuclear reaction for the determination of carbon. The irradiation conditions were optimized by determining the thick targets yields of prompt γ-rays, characteristic of these reactions, in the 3.0–4.2 MeV proton energy range. The quantitative analysis was performed by comparison with standards taking into account the attenuation of γ-rays in the specimens. The uncertainty in the determination of the 10B/11B isotopic ratio and the B/C atomic ratio is about 2% and about 5% respectively. The analysis by EBS, on the other hand, involves the 10B(p,p)10B, 11B(p,p)11B and 12C(p,p)12C elastic scatterings at the 2.0 MeV proton energy. This method too yields satisfactory results. Between the two, PIGE is the method of choice for bulk analysis while EBS is useful in discerning compositional variations in surface regions.