Study of Some Parameters Affecting Efficiency of HpGe Detectors for Accurate Radionuclides Analysis

Document Type : Original Article

Authors

1 Nuclear Engineering Department, Military Technical College, Cairo, Egypt.

2 Nuclear and Radiological Regularity Authority (ENRRA), Nasr city, Cairo, Egypt.

Abstract

Abstract
In fact, optimized and adjusted parameters of analysis techniques are critical issues and lead strongly to accuracy and high confidence of results. This study is mainly focus on investigation (validation and verification; V&V) of some parameters affecting the efficiency and efficacy of HpGe gamma spectrometers; voltage variation, shaping time, type of detectors (n-type or p-type), geometry (size) of detector, source to detector distance and density of the sample matrix. Three different HpGe detectors with their electronics were used to carry out this work. The standard sources; 137Cs, 60Co, 57Co, 133Ba were used. The source-to-detector distance of 25cm was optimized to avoid the coincidence summing and dead-time correction .The efficiency curves of the spectrometers have been measured and presented at the above-mentioned parameters. A simulated reference efficiency curve at different parameters using standard point sources was also produced by Angel-3 software. The noises of electronics due to the electro-mechanical cooling system were also investigated. The optimum parameters were selected for precise analysis of some samples (Black sand and El-Dabaa site) at 3300V and 4000V for p-type and n-type detector respectively. It was observed that n-type detector has better efficiency than p-type especially at low energy below 120 KeV. It covers energies from 10 keV to 3 MeV. The analyses found also that the density has a strong effect on efficiency curve below energy 250 keV. The results obtained at different parameters are discussed, interpreted and presented as figures

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