Automatic interpretation of gamma-ray data obtained in non-destructive activation analysis

The procedure in use at our institute for the extraction of the desired element concentrations in a sample from the peak data obtained by a spectrum analysis program, is described in detail. The method is based on the use of zinc as a single comparator and takes into consideration primary activation products as well as their daughter isotopes. After assigning isotopes to spectrum peaks on the basis of γ-ray energies, the list of possible isotopes is reduced to a list of present isotopes with their concentrations using criteria based on half life, specificity and intensity of γ-rays. For elements not observed, detection limits are estimated. The procedure has been used extensively during the last two years and has shown to produce reliable results.     

A compilation of X- and gamma-ray sensitivities from isotopes produced by the (n, γ) reaction for utilization in instrumental neutron activation analysis

A comprehensive compilation of X- and γ-ray emitting isotopes produced by the (n, γ) reaction is reported in this paper for application to instrumental neutron activation analysis (INAA). The X- and γ-ray sensitivities are computed theoretically by a computer code. Interfering photons from isotopes of neighbouring elements are identified by the code and the percentage interference is computed. Additionally an advantage factor (X-ray: γ-ray sensitivity) is computed, which is a figure of merit for X-ray spectroscopy in INAA. Further, mathematical representation of background continua for typical matrices encountered in INAA allow the calculation of elemental detection limits for the X-ray and γ-ray photons.     

On-line nuclear ash gauge for coal based on gamma-ray transmission techniques

Developments and applications of on-line nuclear gauges in the coal industry are highly requested. In this work, a nuclear ash gauge for coal, based on γ-ray transmission techniques is developed. Single and dual energy γ-ray beams are used to determine the ash content of coal. The percentage ash content as a function of the γ-ray intensities transmitted through coal samples is measured and sensitivity curves are obtained. An empirical formulation relating the ash content values to the γ-ray intensities is derived. Preliminary results show that both single and dual energy γ-ray transmission techniques can be used to give a rapid on-line estimation of the ash concentration values in coal with low cost and reasonable accuracy, but the dual one is much preferable.     

A computer program in ALGOL-60 for the location and evaluation of peaks in Ge(Li) gamma ray spectra

A program is presented for the analysis of γ-ray spectra from Ge(Li) multichannel spectrometer systems. The program is written in ALGOL-60 for off-line working with a large Philips Electrologica X8 computer. It has been extensively used in thermal neutron activation analysis practice.     

Prompt gamma-ray yields from proton bombardment of transition elements (Ti to Zn)

Gamma-ray yields from bombardment with protons of thick targets of Ti, V, Mn, Cr, Fe, Co, Ni, Cu and Zn are tabulated for proton energies ranging between 0.6 and 3.2 MeV. The applications of these reactions for quantitative analysis of these chemical elements are discussed. The sensitivity of this technique of analysis is poorer than the PIXE method for these transition elements, but is sufficient for rapid and accurate quantitative analysis of alloys when elements are present in concentrations down to 1%. The knowledge of the γ-ray energies and intensities produced by the bombardment of these elements with protons is also necessary for solving interferences with several γ-rays induced in light elements, for which the proton induced γ-ray technique is sensitive, without any correction for photon attenuation.     

Kris—A computer program for the least-squares resolution of gamma-ray spectra by half-life and gamma-ray energy

KRIS offers the capability of resolving complex γ-spectra, even when spectra of the individual components are quite similar. A scheme is employed which allows for the use of half-lives as well as γ-ray energies in the least-squares resolution of γ-spectra. Options are also supplied for averaging of repetitive counts, least-squares smoothing of the data, iterative improvement of the weighting factors used in the least-squares solution, and use of either live or clock time counts. The number of control cards required for each sample has been minimized to simplify input. KRIS is written in FORTRAN IV and is being run under Fortran G and the Watfor compiler on the IBM 360/65. The name of the program, KRIS, is not an acronym, nor does it have any scientific significance.     

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.     

Spectra: A computer program for gamma-ray analysis

A computer program infortran iv is presented for the determination of peak location, peak areas and elemental abundances of γ-ray spectra.     

Gamma-ray yield dependence on bulk density and moisture content of a sample of a PGNAA setup: A Monte Carlo study

Monte Carlo calculations were carried out to study the dependence of γ-ray yield on the bulk density and moisture content of a sample in a thermal-neutron capture-based prompt gamma neutron activation analysis (PGNAA) setup. The results of the study showed a strong dependence of the γ-ray yield upon the sample bulk density. An order of magnitude increase in yield of 1.94 and 6.42 MeV prompt γ-rays from calcium in a Portland cement sample was observed for a corresponding order of magnitude increase in the sample bulk density. On the contrary the γ-ray yield has a weak dependence on sample moisture content and an increase of only 20% in yield of 1.94 and 6.42 MeV prompt γ-rays from calcium in the Portland cement sample was observed for an order of magnitude increase in the moisture content of the Portland cement sample. A similar effect of moisture content has been observed on the yield of 1.167 MeV prompt γ-rays from chlorine contaminants in Portland cement samples. For an order of magnitude increase in the moisture content of the sample, a 7 to 12% increase in the yield of the 1.167 MeV chlorine γ-ray was observed for the Portland cement samples containing 1 to 5 wt.% chlorine contaminants. This study has shown that effects of sample moisture content on prompt γ-ray yield from constituents of a Portland cement sample are insignificant in a thermal-neutrons capture-based PGNAA setup.     

Tables of gamma rays emitted by radionuclides produced through photonuclear reactions

The tables have been prepared as an auxiliary for the interpretation of results in photoactivation analysis. They include data concerning the disintegration of radionuclides produced by (γ, n) reactions on all stable isotopes with a relative abundance greater than 1% and by (γ, p) reactions on elements withZ≤39. The γ-rays are listed in ascending order of the energies; half-lives, intensities and other useful informations are also included.     

Determination of photopeak energy in instrumental neutron activation analysis

The precision and accuracy of the peak energy allocation in γ-ray spectrometry govern the subsequent computer processing of the data. By applying the main procedures for peak energy determination to a well-defined case, it is possible to define the minimal statistical uncertainties to be expected. The systematic bias of the energies obtained is caused mainly by changes in the total count rate. A correction can be applied based on the pulser peak. From the precision and the accuracy of the peak energy determination, the scanning width for automatic peak indexing follows.     

New gamma-ray intensities for the <Superscript>14</Superscript>N(n,γ)<Superscript>15</Superscript>N high energy standard and its influence on PGAA and on nuclear quantities

The ¹⁴N(n,γ)¹⁵N reaction is a primary γ-ray source for high energy calibration of detectors. The relative γ-ray-intensities of ¹⁵N and the relative γ-ray detection efficiency function have been simultaneously determined up to 10 MeV from γ-peak areas alone. Absolute γ-ray-intensities were obtained with proper renormalization to known absolute intensity. The influence of these new intensity values are assessed for use in PGAA. Any consistently used set of calibration intensities applied in the creation of library values and for analysis do not influence the concentrations. Contrary to this, quantities based on sums of γ-ray cross sections may provide different answers with the new ¹⁵N intensities and they give means to validate them.     

Determination of boron in Japanese geochemical reference samples by neutron-induced prompt gamma-ray analysis

Determination of ppm levels of B in 21 igneous and sedimentary rocks of the Japanese geochemical reference samples prepared by the Geological Survey of Japan (GSJ) has been performed by neutron-induced prompt γ-ray analysis (PGA) using cold and thermal guided neutron beams of the JRR-3M. Owing to the Doppler broadened γ-ray line of B 478 keV, many elements such as Na, Ni, Cl and so on showed spectral interference in the determination of B. The interference was corrected by computer fitting and a reference peak method. The analytical results obtained by the present method almost agreed with the GSJ values recommended in 1994 within the standard deviation of the recommended values. Sodium contents determined by the PGA in the reference rock samples are also reported.     

Pulsed neutron-based on-line coal analysis

A neutron generator-based on-line coal analysis system is described, capable of measuring the content of the major and minor elements in coal. The system utilizes reactions produced from fast and themal neutrons, as well as from neutron activation with half lives of seconds or minutes. Characteristic γ-rays, detected with BGO detectors are used for the identification of the various chemical elements. The method for the analysis of the γ-ray spectra is presented, and the measurements of coal density, carbon and sulfur content are shown.     

An analytical representation of the response of the NaI(T1) detector for the gamma-ray spectrum analysis

An analytical function for describing the response function of γ-rays from the NaI(Ti) detector was constructed with the purpose of establishing the method of automatic γ-ray spectrum analysis. The response was found to be divided into six portions; the function of each portion joins smoothly to the one representing the adjacent part. Empirical equations for the parameters specifying the response function were found as functions of the γ-ray energy in relation to the detector dimension. The obtained response function was fitted to the observed spectrum by the least squares method. The calculated spectrum agreed well with the observed one.     

Effects of gamma-ray treatment on wastewater toxicity from a rubber products factory

In order to reduce the toxicity of both raw wastewater and effluent from a rubber products factory, γ-ray treatment was applied at different dose levels. The γ-ray treatment did not completely removed the toxicity, suggesting that there were major toxicants other than destroyable organic compounds. Toxicity identification evaluation (TIE phase 1) was conducted to characterize major toxicants using Daphnia magna. The suspected toxicants in both raw wastewater and effluent were mostly filterable materials and EDTA chelatable metals and, to some degree, non-polar organic compounds. Anion-exchange removable compounds, most likely organics, were found only in raw wastewater. Metal analyses showed that zinc and copper concentrations were above levels causing toxicity to D. magna. After 20 kGy γ-ray treatment of raw wastewater, filtrations both at pH 3 and at the initial pH (pH 3.6) showed dramatic change (9 to 77% and 29 to 85%, respectively) in toxicity reduction, suggesting the formation of toxic filterable materials which are stable even at acidic conditions. Unlike raw wastewater, there was no significant change in TIE results after γ-ray treatment at 20 kGy for rubber effluent.     

Quantitative analysis by (p,X) and (p, γ) reactions at low energies

Production of atomic X-rays and nuclear γ-rays by bombardment with 0–3 MeV protons of thick targets is described. In the case of low-Z atomic X-rays, the absorption in the target is very large, while in the case ofK X-rays from high-Z atoms or for γ-rays, this phenomenon is negligible. Both of these reactions can be used for analysis of elements from F to U, and the sensitivities and the accuracies of the determinations are discussed. A table is given showing the γ-ray energies observed in 11 substances and the limits of sensitivity.     

Extraction studies of plutonium from acidic solution using γ-ray induced PC-88A/TBP modified polymers

2-Ethylhexyl-2-ethylhexyl phosphonic acid (PC-88A) and Tributylphosphate (TBP) extractants have been attached to polypropylene (PP) in granular, film and non-woven fabric forms, by a simultaneous γ-ray irradiation method. The extraction of plutonium from the acidic radioactive liquid waste by modified polymers was studied by varying the γ-ray dose. The uptake of plutonium was also studied by polyethylene (PE) in film form. This modified polymer also showed extraction capability for plutonium from nitric acid medium. The uptake of plutonium depends upon the γ-ray dose as well as the nature and source of the polymer. Liquid–solid extraction studies showed that the equivalent amount of uptake of plutonium on TBP–polyethylene film requires twice the γ-ray dose as compare to TBP–polypropylene film. It was observed that at given γ-ray dose polypropylene fabric is not sturdy, compare to the granules and films, and material leach out in aqueous phase. The presence of other solvents like di-methyl formamide (DMF) and cyclohexane during γ-ray irradiation were able to enhance the extraction capabilities. The optimum conditions established during this study was successfully applied for the separation of plutonium, uranium and thorium from the fission products in acidic waste solution.     

Estimation of growth rate of hokutolite from Tamagawa hot-spring,Akita, Japan

The concentrations of radium isotopes and the progenies (²²⁶Ra; ²²⁸Ra and ²²⁸Th) in three hokutolite samples from Tamagawa hot-spring were measured. These isotopes were analyzed by a well-type HPGe γ-ray spectrometer for the 351, 911 and 583 keV γ-ray from ²¹⁴Pb, ²²⁸Ac and ²⁰⁸Tl, respectively, each being in radioactive equilibrium with precursors. Concentration of ²²⁶Ra and ²²⁸Ra were observed to be in the range of 52–85 and 7.1–85 Bq/g, respectively. The activity ratios of ²²⁸Ra/²²⁶Ra and ²²⁸Th/²²⁶Ra provided the estimation of the growth rate (0.09–0.15 mm/y). Estimated ²²⁸Ra/²²⁶Ra activity ratios in hot-spring water from surface of three hokutolite were concordant.     

Quality assurance features of “HYPERMET-PC”

The γ-ray spectrum analysis code HYPERMET-PC has been significantly upgraded since its introduction in the firstk ₀-Users Workshop (1992). Some aspects of the implemented procedures in the new version 5.0, such as the novel approach to handle tandem LFC spectra and the benefit of using ortho-normal polynomials for fitting efficiency curves will be outlined. Having realized the importance of quality assurance in applied γ-ray spectrometry, additional utilities have been incorporated for checking system parameters: nonlinearity, energy resolution, etc. The new Nuclide Identification routine makes the program suitable for qualitative analysis both of NAA and PGAA type.