The determination of boron using 11B(p, α)8Be nuclear reaction

Abstract

Determination of trace quantities of boron is required in various studies of materials and in geology. Using 11B(p, α)8Be nuclear reaction with focused proton beam of 670 keV energy is one of the few microanalytical techniques capable of achieving detection limits in the 5-10 ppm range. The set-up for the determination of boron with high sensitivity was developed at iThemba LABS nuclear microprobe (NMP) facility by using a PIN photodiodes detector. The trace elements such as boron and lithium were analyzed using the nuclear reaction analysis (NRA) method. This project aims at performing microanalysis of boron by NRA method and reaching the developmental phase in which routine, non-destructive boron analyses would be possible at detection limits below 5 ppm. A 228Th source was used for energy calibration of the detector. Five set of standards and unknown samples with a wide range of boron concentrations were analyzed in order to demonstrate the effectiveness of the 11B(p, α)8Be reaction by NRA technique. The standards were used to calibrate the boron yield with respect to their concentration in order to determine the boron concentration of the unknown specimen from the calibrated curve. The determination of the detection limit was also addressed. The concentrations of boron from Mts+Tu 950 glass samples were ranging between 0.17-1.05 wt % and the detection limit of 8.6 ppm for the minimum counts of 100 for 1μC accumulated charge was obtained.