A method for resolution enhancement of interfering peaks in Ge(Li) gamma-ray spectra

A method is proposed for the analysis of interfering peaks in Ge(Li) gamma-ray spectra making use of resolution enhancement by digital resonators. The successive steps of analysis are: (1) the resolution enhancement of multiplets by a special convolution transformation (5 or 7 channels); (2) non-recursive filtering and (3) the elimination of ripples. The final result of the first and second steps is equivalent of a digital resonator. A computional code is quite simple and can be executed by small computers. For opened multiplets one can obtain practically complete separation by means of this method. The limit of identification for a closed doublet of equal intensities amounts to about 0.6 times the FWHM. Subroutine COMPLEX was written in FORTAN IV and BASIC. The validity of the method is shown by an analysis of some synthetic multiplets and the determination of gold traces in Pt-Rh alloy by means of instrumental and destructive activation analysis.     

A program for complete quantitative neutron activation analysis using Ge(Li) detector gamma spectrometry and a small computer

It is shown that the large sophisticated programs designed for big computers can be efficiently used on medium scale machines for complete quantitative neutron activation analysis with Ge(Li) detectors.     

A computer program for calculating Ge(Li) detector counting efficiencies for Marinelli beakers

A novel computing method has been developed to calculate the absolute photopeak efficiency of a Ge(Li) detector for Marinelli beakers of different heights and diameters and with variable density. For each point in the cylindrical sample the detection efficiency is calculated taking into account the distance from the detector and gamma-ray attenuation and the efficiency is integrated numerically over the volume of the sample. The detector is approximated as a point detector with an experimentally determined effective interaction depth. It is necessary to measure the absolute efficiency for a point source located on the detector axis and on a line beside the detector parallel to the axis. The computer program calculates the absolute counting efficiency for Marinelli beakers of any geometry and for any density. The measured and calculated values for three different densities give a good (–2.2%) overall agreement.     

Cross-correlation analysis of Ge(Li) spectra

A sensitive technique is proposed for activation analysis using cross-correlation and improved spectral orthogonality achieved through use of a rectangular zero area digital filter.     

Analysis of interfering peaks in Ge(Li) gamma-ray spectra using the resolution enhancement filters second version of the method

The new results obtained during the last two years are presented against a background of the previous development of the method (first version). The effect of the resolution enhancement filters containing non-recursive smoothing on the wide peaks, advantages of recursive technique and the construction of nonlinear baseline under multiplet to be resolved according to the GUNNINK and NIDAY method are reported in this paper.     

Radial efficiency gradients in Ge(Li) gamma detectors

Counting of radioactive sources in contact with the vacuum container of a Ge(Li) detector may lead to errors because of large efficiency gradients. In order to explore the radial dimension of this problem, several point sources were stepped across in contact with the cap of several detectors, and curves of absolute efficiency against radius were measured. The insensitive core of an open-end coaxial detector reduced the central point-source efficiency at 122 keV at the cap to 20% less than a comparable closed-end detector. In compensation, however, there was a reduction in the radial efficiency gradient. The radial efficiency gradient was approximately proportional to the radius, with the central flattening for the open-end detector superimposed on the trend.     

A program for evaluation of NAA spectra

A program for qualitative and quantitative analysis of spectra obtained by comparative NAA method is described. It includes peak search, calculation of essential peak parameters, isotope identification and estimation of concentrations and/or detection limits of nuclides, corrected for cooling time and decay during measurement. Corrections for blank samples and peak interference are performed as well. Uncertainties estimation of final results are performed according to the error propagation law. The program is aimed to help an experienced user to calculate the results of analysis but the possibility for automatic mode for routine analysis is provided as well.Supported by International Atomic Energy Agency through the research contract 7268/RB.     

A method for systematically analyzing Ge(Li) photopeaks

A relatively straight forward method of fitting Ge(Li) photopeaks with a Gaussian histogram is presented. The method, which is expecially suited to photopeaks which are distributed over a relatively small number of channels, determines photopeak area, pulse height, resolution and the residual background. Results are given to indicate the Gaussian distribution of the experimental data from −1σ to +6σ.     

A simple computer program for high resolution gamma-ray spectra

A computer program is presented, which locates peaks in high-resolution γ-ray spectra and determines their content. The program has been written in Basic; ‘translations’ have been made into Fortran and Algol. For detailed information the reader is referred to the original TNO Report CL 69/137.     

A computer program for the collection,reduction and analysis of echelle spectra

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hardcopy text, comprising the main article and an appendix, is accompanied by a disk containing the compiled program, a manual, the source code and tutorial in ASCII format, and data files. The work presented is a result of the need to facilitate collection, calibration, and extraction of data from an echelle spectrometer employing charge coupled array detection (CCD). A computer program, written using Microsoft's BASIC Professional Development System version 7.1 under MS DOS, is explained and demonstrated. Wavelength calibration requires critical spectrometer dimensions, grating counter settings, and the identification of a single spectral line. Calibration accuracies are better than ± 1 pixel across a 576 × 384 pixel array. Extraction of intensity-normalized spectra for all detected orders requires less than 3 min on a 33 MHz 80386 personal computer with an 80387 math coprocessor.     

Analytical approximation of the gamma ray spectra from germanium detectors

Several functional forms for shape function are tested using data obtained by a Ge(Li) detector. A function built from a Gaussian, a step function and a symmetric or asymmetric tailing on a linear or polynomial background is needed. A new shape function is proposed and superior fit are obtained.     

Photopeak profile of full energy and escape peaks in neutron capture prompt-gamma ray spectra

This paper describes effect of base profile for precise measurement of photon energy in prompt -ray analysis (PGA). The base profile has been examined in the vicinity of full energy (FE), single escape and double escape peaks. Major origins of step-wise base profiles are single and double escape events for triple photon annihilation and single and double Compton escape events for double photon annihilation in the detector, in addition to general events for the FE peak. A formula has been proposed for the quantitative characterization of the base profile.     

Computer program for processing gamma spectra in neutron activation analysis

A program based on the method of least squares and written in the ALGOL-60 code was developed for data processing in the activation analysis of biological substances. The applicability of the program was checked on synthetic mixtures of the radioisotopes⁶⁴Cu,^69mZn and⁵⁶Mn measured with a scintillation γ-spectrometer.     

Multielement neutron activation analysis of biological materials using chemical group separation and Ge(Li) gamma spectrometry

Neutron activation analysis (NAA) for the determination of some trace elements in biological materials is described. The method presented permits the simple and rapid determination of Se, Ag, Au, Sb, Pt (via¹⁹⁹Au), Hg, Co, Ni (via⁵⁸Co), Fe, Zn, Mo, Sn, Cr, Cd, Cu and As after radiochemical separation from Na, K, Cs, Rb and partially Br. For this purpose, postirradiation separation by extraction with mercury or zinc amalgam was used. Separation of gold by extraction with ethyl acetate or by precipitation with dimethylglyoxime was applied for the determination of gold and platinum in biological materials.     

Calculation of the absolute peak efficiency of Ge and Ge(Li) detectors for different counting geometries

A new method is presented to calculate with improved accuracy the absolute peak efficiency of cylindrical Ge and Ge(Li) detectors for point, disk and cylinder sources, positioned at any source-detector distance. Moreover attention was paid to true-coincidence effects. The method is extensively tested and applied for the analysis of reference materials. The accuracy turned out to be 3% or better. Research associate of the “Nationaal Fonds voor Wetenschappelijk Onderzoek”.     

A program for evaluation of gamma-spectra (ANA)

A program (ANA) for evaluation of -spectra is reported. The program is based on a nonlinear least-squares procedure which uses a composite algorithm called KATOK. The program includes spectrum visualization, energy and FWHM calibration, automatic peak search with data preparation, possibility for manual data preparation and utilities.     

A computer program for a general case evaluation of the expanded uncertainty

The ISO Guide to the Expression of Uncertainty in Measurement provides a uniform method for the evaluation of combined standard uncertainty of a measurand whose expectation and standard deviation are stable over the measurement period. However, the method provided for the evaluation of the expanded uncertainty is not complete. Particularly, it does not include the case where the contributing components are correlated. Also, the probability distribution of the combined uncertainty must be close to a Normal distribution otherwise other methods must be used. The method presented here, which is implemented in a computer program, is based on a combination of the ISO guide method and Monte-Carlo simulation.The Monte-Carlo Simulation can obtain the data needed for the evaluation of the expanded and standard uncertainties directly from the measurement equation (that defines the measurand in terms of the contributing components) or from a spreadsheet-like format. Some sample results obtained by the computer program using both methods are compared and discussed.     

A new improved expression for gamma-ray detection efficiency of Ge(Li) detectors

In the present paper, a new improved expression for -ray detection efficiency of Ge(Li) detectors, ⁰ , is given. It is represented as a continuous function of x (viz. E ^–1) with a maximum and decreases very rapidly to a small positive value as -ray energy, E, drops to 40 keV or lower, but slowly as E rises to 1.7 MeV or higher. Since it can well represent the whole physical process of the -ray detection, this expression may be one of the simplest and most precise representations, for ⁰ at the present time.     

The determination of the Si and Ge content in SiGe alloy by gamma ray absorption spectroscopy

γ-Ray absorption spectroscopy has been used to accurately determine the Si and Ge content in SiGe alloys. This technique provides a fast, accurate, and non-destructive method for determining concentrations of components in binary systems. This work supported by the U. S. Atomic Energy Commission.