T. Belgya

Introducing HYPERMET-PC for automatic analysis of complex gamma-ray spectra

In short time activation analysis prompt gamma-activation analysis and in high rate γ-ray spectroscopy in general, the shape parameters for peaks and back ground usually vary, rendering spectrum evaluation codes based on a fixed shape calibration unsuitable. An interactive version of the well-known, fully automatic γ-ray spectrum analysis code HYPERMET has been developed in C ++ for the IBM-PC. It runs under MS-DOS, in conventional memory, and can handle up to 16k-channel spectra, recorded with CANBERRAs System 100 and AccuSpec and with ORTECs ACE plug-in MCA cards. A Windows-like graphics environment is provided with mouse controlled pull-down menus, pop-up windows and rubber band expansion. All basic features of HYPERMET such as fully automatic peak search, nonlinear fitting of multiplets with automatically adjusted Gaussian peak widths exponential tails and a complex background function have been retained. All details of the fitting procedure are recorded in a data base, hence any fitted region can be retrieved and modified interactively, even after a fully automatic spectrum evaluation. The program also provides an output peak list in SAMPO90 format for further processing. The latter format is widely used in a number of sample analysis programs such as KAYZERO a software package fork0 standardization in neutron activation analysis.

Cold neutron PGAA facility at Budapest

The new cold neutron prompt gamma activation analysis (PGAA) facility provides improved capabilities for routine prompt gamma analysis and for the investigation of radiative neutron capture. The versatile beam chopper makes possible time-of-flight measurements and the acquisition of prompt and decay spectra simultaneously. The chopped beam PGAA technique combines the advantages of the in-beam measurement and the greater simplicity of decay gamma spectra.

The 235U(n, f) prompt fission neutron spectrum at 100 K input neutron energy

Abstract A measurement of the 235U prompt fission neutron spectrum (PFNS) was performed at the Budapest Nuclear Research Reactor at 100 K incident neutron energy. The motivation for this investigation was to verify some literature data measured over the past 20 years that contradict the Los Alamos model, as well as integral data, benchmark (Keff) experiments, and recent spectral data taken at 0.5 MeV incident neutron energy. The measured spectra using three neutron detectors are in excellent agreement with each other. The average spectrum confirms literature data within the error bars in the neutron energy range of 0.7 to 10 MeV. However, the present PFNS shape cannot predict integral experimental data. It seems to be clear now that the disagreement between microscopic and macroscopic data is not connected with a systematic experimental error in the PFNS at low incident neutron energy.

Recent developments in HYPERMET PC

HYPERMET PC is a user-friendly γ-ray spectrum analysis software package developed at Budapest, mainly for the purpose of prompt-γ neutron activation analysis (PGAA). The peak fitting algorithm is an improved version of the well-known HYPERMET code, and contains a partial peak-parameter calibration to describe peak shapes more accurately in the wide energy range typical for prompt-γ spectra. A nuclide identification routine has also been developed using a new PGAA library, shown in a parallel paper. The new module for quantitative PGAA includes all the features necessary to obtain concentration values for elements.

The new prompt gamma-activation analysis facility at Budapest

Prompt gamma-activation analysis (PGAA) is an important complementary technique to conventional instrumental activation analysis that can be successfully used in a number of cases when INAA is not applicable. Therefore, a PGAA facility has been constructed at the recently refurbished and upgraded Budapest Research Reactor. It occupies the end position of a new curved themal guide of 30 m length and 2.5×10 cm2 cross section which provides a clean beam of low energy neutrons. The sophisticated HPGe-BGO γ-ray spectrometer system can be operated in Compton-suppression and pair-spectrometer modes simultaneously. The octal splitting of the main BGO improves efficient pair mode operation when coincidences between pairs of opposite segments and the HPGe detector are required separately. Gamma-gamma coincidence measurements will also be possible when the new multiparameter data acquisition system is completed. One of the main tasks at the new facility will be the accumulation of new spectroscopic data for detector calibration and standardisation, as well as for the construction of a more accurate prompt γ-ray library for the chemical elements. Various applications are planned, such as the determination of hydrogen in fullerenes and of toxic trace elements in environmental samples.

Prompt Gamma-Ray Spectrum Catalog

The spectra and the tables presented in this chapter are the result of many years of experiments in Budapest followed by a thorough evaluation performed in at the Lawrence Berkeley National Laboratory. Our goal has been to provide a data library that is based mainly on measurements performed using a single, well-calibrated, experimental setup in one laboratory. Common systematic errors, which we strived to minimize, often cancel when comparing the measurements, unlike comparisons of measurements from different laboratories. The data from the literature are also included for completeness in the evaluated dataset; however their intensities were normalized to the experimental data measured in Budapest.

The new prompt gamma-ray catalogue for PGAA

A new catalogue of subthermal neutron-induced prompt gamma rays has been created for 79 elements, from hydrogen to uranium (including fission), on the basis of recent measurements at the Budapest guided-neutron PGAA facility. New energy values have been measured using 35Cl neutron-capture gamma rays, while the gamma-ray production cross-sections have been determined with respect to the 1H thermal capture cross-section. The elemental data have been compared with thermal neutron-capture data for individual nuclides from the Evaluated Nuclear Structure Data File, ENSDF, hence isotope identifications could be made. The catalogue contains elemental spectra and a table with nearly 7000 gamma rays with relative intensity over 1% of the strongest line. The average accuracy is about 0.08 keV for energies and about 5% for cross-sections in the whole energy range, from about 40 keV to 11 MeV.

A new gamma-ray spectrum catalog for PGAA

A major obstacle to the use of the prompt gamma activation analysis (PGAA) method has so far been the lack of a suitable library. Therefore, new measurements have been performed at the PGAA facility at Budapest Research Reactor (BRR) in order to create a prompt γ-ray catalog for qualitative and quantitative analysis. Prompt γ-ray energies and associated k0-factors have been determined by internal standardization. The resulting catalog contains prompt γ-ray data from neutron capture and other reactions such as (n,α), and decay γ-ray data from short-lived reaction products. Data have been measured for nearly all stable elements, from hydrogen to uranium. Generally, data for several isotopes are given, to enable isotopic analysis as well.

In Situ Determination of Hydrogen Inside a Catalytic Reactor Using Prompt γ [Gamma] Activation Analysis

Prompt gamma activation analysis (PGAA) has been further developed to analyze reacting components inside a chemical reactor. The new method, in situ PGAA, was used to determine the hydrogen-to-palladium molar ratio under various conditions of palladium-catalyzed alkyne hydrogenation. The H/Pd molar ratio was successfully measured in the range of 0.1-1.0 in an approximately 2-g catalytic reactor containing a few milligrams of palladium catalyst. The amount of hydrogen was only a few tens of micrograms, and the detection limit was approximately 5 microg, i.e., at ppm level compared to the whole reactor. The description of the device, methodological developments, a feasibility study, and results of a series of catalytic measurements are presented.

A new gamma-ray spectrum catalog and library for PGAA

New measurements have been performed at the PGAA facility at the Budapest Research Reactor (BRR) in order to create a prompt γ-ray catalog for qualitative and quantitative analysis. The measured spectra were accurately analyzed by HYPERMET-PC. Prompt γ-ray energies and associated γ-ray production cross-sections have been determined by internal standardization. The resulting catalog contains prompt γ-ray data from neutron capture and other reactions such as (n,α), and decay γ-ray data from short-lived reaction products. Data have been measured for nearly all stable elements, from hydrogen to uranium. Generally, data for several isotopes are given, to enable isotopic analysis as well. The whole library, including elemental spectra, will be available as a book.