Uso de sistema de coincidência gama-gama associado à espectroscopia simples em medidas de análise por ativação neutrônica

Abstract

In this study was the developed a γγ acquisition system that make possible to perform Neutron Activation Analysis by single gamma spectroscopy and coincidence γγ spectroscospy simultaneously for the elements As, Co, Cs, La, Sc, Se e Sm. In order to achieve this main goal preliminary measurements in γγ acquisition systems with analogical and digital instrumentation were performed to check the efficiency of technique through measurements of synthetic standard and certified reference material. These measurements also helped to choose the most suitable instrumentation for the development of the acquisition system in the Applied Nuclear Physics Laboratory (LFNA) located at IPEN. The developed system is composed by a CAEN v1724 digitizer board and two hyperpure Germanium detectors. The data acquisition is controled by MC2Analyzer software, which provide raw data of energy and time information of the recorded pulses.Two softwares for data reduction that allow the set the coincident events from single spectra were developed: DPP which prepare the data to be analyzed with softwares for bidimensional espectra.; and AnalisaCaen which handle the data to be analyzed with softwares for single spectra. Determination of the concentration for some elements in certified reference materials and sytnhetic standards were performed applying the conventional and coincidence Neutron Activation Analysis methods. Accuracy and precision of the results obtained by Instrumental Neutron Activation Analysis and Coincidence Instrumental Neutron Activation Analysis were performed by E n score criteria. The results obtained with this system allowed to check the reliability on the determination for the elements As, Co, Cs, La, Sc, Se and Sm. In some cases the concentration results obtained with coincidence measurements were better than the results from single spectroscopy.

Aplicação de Técnicas de Coincidência Gama-Gama No LFNA-CRPQ

“…No trabalho de Ribeiro Jr. [11], verificou-se que o uso da técnica de Análise por Ativação Neutrônica (NAA) com medidas em coincidência permitiu determinar com boa precisão e exatidão concentrações de Sc, Co, Cs, Se, As, La, Sb e Sm, mesmo em matrizes altamente complexas -ao custo de tempos de aquisição bem mais longos, é importante que se diga.…”