A database for QA/QC in neutron activation analysis and gamma-ray spectrometry

A database has been designed for storing, retrieving and analyzing information about samples, experimental conditions and results obtained by neutron activation analysis and gamma-ray spectrometry. It has been created using Microsoft ACCESS 2002 under a Windows operating system. The database has been designed not only for saving information but also for quality assurance and quality control purposes. The structure of the relational design has been discussed and demonstrated with a new graphical feature of ACCESS 2002 called PIVOTCHART.     

An automated gamma-ray counting system for fast neutron activation analysis

An automated gamma-ray counting system was designed and built for use in counting long-lived nuclides (T>hr) produced during analysis by fast neutron activation. The system is mechanically simple, vet interfaced to sophisticated control and counting equipment for completely automated counting.     

Design of a new instrument for cold neutron prompt gamma-ray activation analysis at NIST

A new instrument for cold neutron prompt gamma-ray activation analysis (CNPGAA) is being designed and constructed at the NIST Center for Neutron Research (NCNR). The new instrument is expected to have lower gamma-ray and neutron background and better detection limits for most elements than the current cold neutron PGAA instrument. Other advantages over the current facility will include the ability to analyze larger samples and greater overall measurement capability due to the addition of scanning stages, cryostats, and sample changers.     

In-situ CeBr3 gamma-ray spectrometry for radioactivity analysis of soil

Journal of Radioanalytical and Nuclear Chemistry - A CeBr3 scintillation detector was applied for in situ gamma-ray spectrometry for radioactivity assessment of soil. The full energy peak...     

14 MeV neutron activation analysis of ternary copper ilver selenide by X-ray and gamma-ray spectrometry

14 MeV neutron activation of ternary copper silver selenide gives rise to a predominant activity from the 0.511 MeV annihilation peak from the three elements when -ray spectrometry is used. To overcome the interference problems, X-ray spectrometry was applied to the simultaneous nondestructive determination of silver and selenium, after which copper can be determined by -ray spectrometry. The results of analysis show a relative error not higher than ±5%, when the samples were diluted with H₃BO₃ /90%/ to minimize the interelement effects.     

A gamma-spectrometry system for activation analysis

Based on a Preloaded Digital Filter operating on a 20% n-type HpGe detector with transistor reset preamplifier, and on a software implementation of a loss-free counting MCA, storing immediately into the multi-megabyte main memory of a low-cost 486-type PC, the new system enables the collection of up to 120 pairs of simultaneously recorded loss-corrected and non-corrected spectra of 16 k channels each, in a true sequence without time gaps in between, at a throughput rate of up to 140 kc/s. Intended for activation analysis of short-lived isomeric transitions, the system for the first time makes possible peak to background optimizations and even separations of lines with different half-lives without an a priori knowledge of sample composition by summing up appropriate numbers of spectra over appropriate intervals of time. The speed of this programmable system also made possible the direct comparison of two methods of real-time correction of counting loss, by simultaneous recording of LFC-corrected, ZDT^tm -corrected and non-corrected spectra together with their corresponding weighting factor distributions.     

On the construction of a new instrument for cold-neutron prompt gamma-ray activation analysis at the FRM-II

Summary A new flexible prompt gamma-ray activation analysis (PGAA) station will be installed and operated at the FRM-II reactor in Garching at the beginning of the year 2006. The PGAA station has been moved from the Paul Scherrer Institute (PSI), Villigen, Switzerland and is now being re-designed for three different experimental applications: PGAA instrument, cold neutron tomography setup and a compact Ge-array. Simulations of the beam guide have been carried out in order to yield the best conditions for each of the instruments, and are discussed here. A number of the PGAA applications are listed here. A new project dealing with a systematic measurement of bulky composition of small amount of meteorites (~100 mg) is proposed. Results of a test measurement of the Dhurmasala meteorite composition at the PGAA station at the Budapest Research Reactor are presented. Expected parameters of the PGAA facility at FRM-II are compared both with those at PSI and with the Budapest facility.     

A computer program for automatic gamma-ray spectra analysis with isotope identification for the purpose of activation analysis

A FORTRAN IV program for a PDP-9 computer, with 16 K storage capacity, is developed performing automatic analysis of complex γ-spectra, taken with Ge(Li) detectors. It searches for full energy peaks and evaluates the peak areas. The program features an automatically performed isotope identification. It is written in such a flexible manner that after reactor irradiation, spectra from samples of any composition can be evaluated for activation analysis.     

Epithermal instrumental neutron activation analysis in conjunction with anti-coincidence gamma-ray spectrometry for investigating iodine levels in Canadian foods

In order to reduce interferences from high activities of ²⁴Na, ⁵⁶Mn, ⁸²Br, and ³⁸Cl as well as to improve detection limits, precision, and accuracy of measuring iodine levels in biological materials, foods and diets in particular, an epithermal instrumental neutron activation analysis (EINAA) method in conjunction with anti-coincidence (EINAA-AC) gamma-ray spectrometry was employed. The Compton scattering background in the region of the 442.9-keV photopeak of ¹²⁸I was significantly suppressed by anti-coincidence counting. In order to validate the EINAA-AC method as well as to evaluate its broad applicability to diverse types of biological material, 17 NIST and IAEA reference materials containing very low to high levels of iodine as well as interfering elements were analyzed by the EINAA-AC method. The samples were irradiated in the cadmium-lined pneumatic site at a neutron flux of 2 × 10¹¹ cm^?2 s^?1 of the Dalhousie University SLOWPOKE-2 Reactor (DUSR) facility for 10 or 20 min followed by 1-min decay and 30-min counting. The detection limit for iodine by EINAA-AC was improved by a factor of 2–5 compared to EINAA depending on the sample matrix and other factors, and a limit of 3–5 μg kg^?1 was achieved for low-salt foods. We found the RSD to be about ±5 % above 200, increasing to ±10 % at 20, and then to greater than ±30 % at about 5 μg kg^?1 iodine levels.     

A comparative study of computer programs used for analyzing gamma-ray spectra in activation analysis

The paper describes the results of a comparison of programs, used for analyzing γ-ray spectra. Testspectra were measured and distributed to a group of specialists for activation analysis. The values of the calculated peak areas were collected and compared. The detailed results are presented in the paper, generally one can say, that the agreement is better with intense peaks than with weak ones and that with overlapping peaks many of the programs fail.     

HyperLab: A new concept in gamma-ray spectrum analysis

HyperLab is a new Ge gamma-ray analysis code for MS Windows, developed using object-oriented design. The novel feature of the program is the extensive use of relational database technology, which allows the efficient storage and handling of any digital data encountered in gamma-ray spectroscopy. While preserving the main concept of the predecessors (HYPERMET and its derivatives) for semi-automatic analysis of multichannel pulse-height spectra, the substantially reshaped basic routines vastly improved the stability and reliability of peak fitting. New features include the fitting of peaks with high energy tail, as well as library-directed Graphical Isotope Identification. Procedures for efficiency, nonlinearity, etc. calibrations are now highly automated. By exploiting all the benefits of MS Windows technology (point-and-click simplicity in task executions, intelligent mouse pointer, etc.) HyperLab is a versatile and user-friendly tool which the discriminating spectroscopist will find of great value.     

Low-level gamma-ray spectrometry for environmental samples

Low-level gamma-ray spectrometry with large volume HPGe detectors has been widely used in analysis of environmental radionuclides. The reasons are excellent energy resolution and high efficiency that permits selective and non-destructive analyses of several radionuclides in composite samples. Although the most effective way of increasing the sensitivity of a gamma-ray spectrometer is to increase counting efficiency and the amount of the sample, very often the only possible way is to decrease the detector’s background. The typical background components of a low-level HPGe detector, not situated deep underground, are cosmic radiation (cosmic muons, neutrons and activation products), radioactivity of construction materials, radon and its progenies. A review of Monte Carlo simulations of background components of HPGe detectors, and their characteristics in coincidence and anti-Compton mode of operation are presented and discussed.     

Some practical procedures in computerized thermal neutron activation analysis with Ge(Li) gamma-ray spectrometry

The practical use of a correction procedure for random coincidence losses, the determination of the detection limit and the standardization of measuring conditions are described. Special correction methods for the interference of the Cu analysis by²⁴Na, the burn-up of the radioactive nuclide formed and the interference of the Pt determination by Au are also given.     

Software for X- and gamma-ray spectrometry

Summary A computational approach to the true-coincidence summing correction factor evaluating was developed on the basis of the extended version of the MCNP - a general Monte Carlo N-particle transport code. A specially developed utility program generates the MCNP input on the basis of a routinely updated Evaluated Nuclear Structure Data File (ENSDF) library. Necessary information is automatically added to allow accurate simulating of the emission of correlated particles accompanying the decay of a particular radionuclide, including emission of annihilation quanta, K- and L- X-rays, β-particles and conversion electrons. Gamma-ray angular correlations as well as lifetimes of the nuclear excited states are also taken into account. The approach is applicable to correction factor evaluation for ordinary single- and multi-detector spectrometers as well as for Compton suppression systems. The paper describes the developed computational scheme as well as presents the results of its preliminary testing for the case of both point and volumetric sources.     

Application of prompt gamma-ray spectrometry to helium-3-induced activation of boron

An assessment was made of the analytical potential of the exoergic reactions on boron, induced by³He⁺ beams. Possible interferences from C, N and O were studied. Gamma-rays originating from (³He, n), (³He, d), (³He, d), (³He, ) and Coulomb excitation were identified. Possible practical applications in boron studies are indicated.     

Radiometric analysis of some building materials using gamma-ray spectrometry

Journal of Radioanalytical and Nuclear Chemistry - The present study focuses on the effect of natural radioactivity of some common building materials to humans. The main radiological risk...