Efficiency calibration of a coaxial HPGe detector-Marinelli beaker geometry using an 152Eu source prepared in epoxy matrix and its validation by efficiency transfer method

In this paper, the Monte Carlo efficiency transfer method was used to calibrate the full energy peak efficiency (FEPE) of a coaxial p-type HPGe detector. The gamma standard radioactive sources including 22Na, 54Mn, 57Co, 60Co, 65Zn, 109Cd,133Ba, 137Cs, 154Eu, 207Bi, 241Am were measured at different positions on-center of detector with the distance of 5, 10, 15, 20, 25 cm. Besides, a cylindrical sample containing standard mixed nuclides solution was also measured at surface of the detector. The experimental FEPE curves as function of gamma energy for these geometries were determined with the coincidence-summing corrections. A HPGe detector model based on the specifications of manufacturer was built to directly calculate the FEPE for the geometries by Monte Carlo simulations with MCNP6 code. However, these simulated FEPEs show a quite high discrepancy from experimental FEPEs. Then, the FEPEs were calculated by the efficiency transfer method with the efficiency curve for point source at distance of 25 cm as the reference data. A good agreement was obtained between the calculated results by the Monte Carlo efficiency transfer method and experimental results. The comparisons between experimental and calculated FEPE showed that the relative deviations were mostly within +/-4% in the energy range of 53-1770 keV.

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Modeling the impact of uncertainty in detector specification on efficiency values of a HPGe detector using ANGLE software

Nuclear Technology and Radiation Protection ◽

10.2298/ntrp1302169m ◽

2013 ◽

Vol 28 (2) ◽

pp. 169-181 ◽

Cited By ~ 6

Author(s):

Maurice Miller ◽

Mitko Voutchkov

Keyword(s):

Hpge Detector ◽

Efficiency Curve ◽

Peak Efficiency ◽

Detector Characterization ◽

Transfer Method ◽

P Type ◽

The Impact ◽

First Time ◽

Efficiency Transfer Method ◽

Full Peak

The objective of this study is to model the impact of uncertainties in the engineering specifications of a typical p-type HPGe detector on the efficiency values when the measured soil sample is in contact geometry with the detector. We introduce a parameter named the normalized sensitivity impact which allows a comparative analysis to be made of the impact of the detector specification uncertainties and develop a correction factor table for the most important parameters. The areas of the detector most susceptible to error were found to be the crystal geometry, vacuum layer above the crystal and the bulletizing radius. In all cases the major impacts were mathematically modeled - for the first time - and found to vary either quadratically or logarithmically over the energy range of 180 keV to 1500 keV. Finally, we propose a set of detector characterization values that may be used in ANGLE for generating a reference efficiency curve using the efficiency transfer method inherent in this software. These values are to be used with the understanding that their uncertainty impact on the full-peak efficiency though not very significant in this counting arrangement, is not non-zero.

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