Reduction of beta-interference in gamma-spectrometric measurements of neutron-irradiated geological material

Abstract

The analytical technique for instrumental neutron activation analysis, when applied to geological materials, is improved by introducing an lectromagnetic field between sample and detector. This field lowers the bremsstrahlung background intensity in the gamma-spectrum, by reducing the number of beta-particles reaching the detector. Thus, precision, accuracy and lower detection limit are improved. In this work the technique has been used on an alkalisyenite and on meteoritic material, rocks containing high quantities of sodium and iron, respectively. After neutron irradiation, the induced nuclides²⁴Na and⁵⁹Fe are responsible for high bremsstrahlung interference, which under normal analytical conditions would mask any X-ray or gamma-ray peaks of interest. The technique is easily applied to multielement analysis of geological and biological material (although the latter is not treated in this paper). It can be combined with sophisticated spectrum-treating techniques such as spectrum stripping and spectrum smoothing, or coincidence-anticoincidence circuits.