Study On Prompt-Gamma Neutron Activation Analysis And K₀ Method

Neutron-induced prompt-gamma activation analysis, PGNAA, is a method by detecting the gamma rays promptly emitted from the nuclear reactions. It is an important nuclear method for rapid and nondestructive analysis of some trace and major components in many fields. Particularly, PGNAA works well for the analysis of light elements such as hydrogen, boron, nitrogen, silicon, and the elements with high neutron capture cross sections, which cannot be readily analyzed by instrumental neutron activation analysis.This paper presents our investigation on the PGNAA including its setup and the methodology study. There are four major aspects as briefly described below:1, Since 2003, a new PGNAA facility has been operational at the 15 MW HWRR in the China Institute of Atomic Energy. The PGNAA facility is composed of a sample box, a sample holder, a detection system and a shielding system for neutrons and gamma rays.2, Efficiency calibration over a wide energy range for germanium (Ge) detectors: As we all know, the calibration of efficiency to a broad energy range is very difficult. One of important reasons is that only a limited number of calibrated radioactive standards are available and none of them provide Y -rays with energies above 4.8 MeV. In our studies, the decay gamma rays from some calibrated radioactive standards and prompt gamma rays emitted from 35Cl(n, y )36C1 were used for the detector efficiency calibration with the energy range from 0.09 to 8 MeV. In the calibration, least square fitting for all measured data with either one high order polynomial or fitting piecewise with several low order polynomials were used, and the latter was more accurate.3, The k0 method was used for the calculation of the elements content. The PGAA k0 factors of some elements relative to the 1951 keV of36Cl were measured. They aregenerally in good agreement with those measured by other countries. 4, The direct counting rate measurement was employed. The method is more convenient for multielement determinations. If we know the mass of an element (single standard) and measured the analytical peak count rates of this element and the elements to be determined, the elements of interest can be determined because the ratios of the peak counting rates among elements are constant for given measurement conditions. This method has been validated in some standard samples.,...