A new theoretical approach was developed for computing the FEP efficiency of HPGe and scintillation detectors using the concept of probability function. Thus integral expressions for the FEP ...efficiency were developed using three probability functions. Starting from the integral expression of the FEP efficiency and using integral means and Chebyshev functional, new expressions of the FEP efficiency, detector response, and self-attenuation factors were obtained. Also, the new approach provides new insights useful for gamma spectrometry measurements. Two practical applications of this approach are described.
•A new theoretical approach for computing the FEP efficiency is described.•Integral expressions of the FEP efficiency were developed.•New expressions of the FEP efficiency were obtained using integral means.•New expressions were developed for self-attenuation factors.•Two practical applications of the new approach are described.
In this work, a classical approach was used for calibrating the GESPECOR detector model for computing the full-energy peak efficiency of p-type coaxial HPGe detectors that is based on the use of ...linear least squares optimization. The key element of the work is the multiplicative model developed for approximating the values of the full-energy peak efficiency provided by GESPECOR code. It was linearized using the logarithmic transformation to allow an easy use of the linear least squares optimization. A procedure was also developed to estimate the optimal values of the parameters, describing the p-type coaxial HPGe detectors. Its application to a Canberra detector GC3018 showed that it is possible to determine accurate values of the full-energy peak efficiency computed by GESPECOR code using the optimized parameter values.
A simple method has been developed for determining the activity of large-area beta reference sources in anodized aluminum foils. It is based on the modeling of the transmission of beta rays through ...thin foils in planar geometry using Monte Carlo simulation. The method was checked experimentally and measurement results show that the activity of large-area beta reference sources in anodized aluminum foils can be measured with standard uncertainties smaller than the limit of 10% required by ISO 8769.
•A method for determining the activity of large-area beta sources is presented.•The method is based on a model of electron transport in planar geometry.•The method makes use of linear programming for determining the activity.•The uncertainty of the method is smaller than 10%.
A novel virtual point detector model was developed for cylindrical high purity germanium detectors that are widely used in gamma-ray spectrometry. According to this model, the full energy peak ...efficiency response of these detectors can be computed by replacing the detector with a virtual point detector located at the center of the detector crystal. In fact, the novel model makes the transfer of the FEP efficiency response from a reference point source to a given point source, both sources being located on a line that passes through the virtual point detector. The model was tested and provided accurate results.
•A novel virtual point detector model is described in this paper.•The FEP efficiency response is approximated by a power function model.•The novel model has a solid theoretical basis.•Two computational ways were developed to apply in practice the model.•This model may provide accurate values of the FEP efficiency response.
The numerical modeling of large-area beta sources constructed from anodized-aluminum foils is described in this paper. Based on a realistic model for the activity depth distribution, theoretical ...lower and upper bounds for the efficiency and the transmission coefficient were calculated and used to analyze the comparison method recommended by ISO 8769 for measuring the surface emission rate. The analysis shows that this method can provide measurement results with relative standard uncertainties smaller than 3% for high energy beta emitters such as 90Sr–90Y, 36Cl and 204Tl.
This paper provides guidance for determining the neutron activation profile of core drill samples taken from the biological shield of nuclear reactors using gamma spectrometry measurements. Thus, it ...provides guidance for selecting a model of the right form to fit data and using least squares methods for model fitting. The activity profiles of two core samples taken from the biological shield of a nuclear reactor were determined. The effective activation depth and the total activity of core samples along with their uncertainties were computed by Monte Carlo simulation.
•The paper provides guidance for determining the activity profile of core drill samples.•Effective activation depth and total activity are computed by Monte Carlo simulation.•Exponential fit is the simplest way for evaluating the activity profile of core samples.
In this paper, the application of the efficiency transfer method to the evaluation of the surface beta contamination is described. Using efficiency transfer factors, the reference calibration factor ...of contamination monitors is corrected, to obtain the calibration factor for an actual contamination source. The experimental part of the paper illustrates the applicability of the method to the direct measurement of the surface beta contamination.
•Efficiency transfer method is applied to surface beta contamination measurements.•Efficiency transfer factors are computed by Monte Carlo method.•Efficiency transfer factors are computed using the available information on sources.•Calibration factor of contamination monitors is corrected using transfer factors.
This paper describes a new approach in evaluating the surface beta contamination using the direct method of measurement. It makes use of previous results obtained in numerical modeling of electron ...transport in planar geometry and is mainly based on the estimation of the efficiency of contamination sources for beta radiation and its standard uncertainty using the available information concerning the component materials of the sources and their main parameters. Experimental results illustrate the appropriateness of the new approach for surface beta contamination measurements.
•A new approach in evaluating surface beta contamination is described.•The approach is based on the evaluation of the source efficiency for beta radiation.•It alleviates difficulties in uncertainty evaluation in beta contamination measurements.
The assessment of uncertainty in free release measurements by integral gamma scanning method is described and applied to the measurement of homogeneous and heterogeneous waste drums. It is based on ...the propagation of distributions using the Monte Carlo method. In addition, two techniques for the uncertainty reduction are also described. The first technique makes use of containers constructed from two concentric cylinders and the second technique is based on the measurement of a group of waste drums. It is proved that the uncertainty of clearance measurements can be reduced using both techniques.
•Uncertainty assessment in free release measurements is described.•Uncertainty assessment is based on the propagation of distributions.•Two techniques for uncertainty reduction are also described.•It is proved that the uncertainty can be reduced using both techniques.
The paper presents a new approach in the integral gamma scanning of rotating waste drums based on solving a first-kind Fredholm integral equation using a small number of measurements. Both numerical ...experiments and experimental results show that the nuclide inventory of waste drums can be determined accurately using the new approach especially when the waste drums contain multi-gamma emitters.
► A new approach in the integral gamma scanning of rotating waste drums is presented. ► Approach is based on solving a Fredholm integral equation using several measurements. ► Extensive numerical experiments were performed for testing the new approach. ► The accuracy of the gamma scanning is improved especially for multi-gamma emitters. ► Accuracy better than 16% was obtained in the measurement of a waste drum with 152Eu.
