Accurate and efficient determination of boron content in volcanic rocks byneutron induced prompt gamma-ray analysis

An accurate and efficient analytical method using neutron-induced prompt ga mma-ray was developed for the determination of boron contents in volcanic r ocks. We corrected the effect of sample geometry and flux fluctuation by us ing silicon as an internal standard. However, we found that the slopes of t he calibration line vary among volcanic samples with different matrix. Beca use the increase of boron activity correlates positively with gamma-ray cou nt rate of hydrogen (water), we call this as the hydrogen effect. The hydro gen effect was confirmed by our experiment in which the boron activities sh owed systematic increase with the amount of added hydrogen (water). Most vo lcanic rocks, however, contain little water (<wt.%) to show this effect. We determined boron contents in various volcanic rocks in order to confirm th e validity of the procedure that we established. The analyzed boron content s agreed well with the previous reported values. For efficient PGA of boron in volcanic rocks, we recommend JB-2 (GSJ standard rock) as a single geoch emical standard, because of its high boron content (31.2 ppm).