Measurement of the branching ratio related to the internal pair production of Y-90.

The aim of the work is to determine the number of positron-electron pair creation in the E0 transition between the 1760.7 keV level and the ground level of the Zr-90 nucleus at the Y-90 decay. The number of conversions is determined from the number of 511 keV photons originating from positron annihilation corrected for the annihilation of positrons in flight.

Activity measurements and determination of nuclear decay data of Ho in the MRTDosimetry project.

Holmium-166 is a high-energy β-emitter radionuclide (~ 1.8 MeV) with a short half-life (~26.8h) that offers great potential as an alternative to Y for the treatment of liver cancer based on radioembolization.

Measurement of absolute γ-ray emission probabilities in the decay of Ac in equilibrium with its progeny.

The emission probabilities of γ rays produced in the Ac decay series were determined by high-resolution γ-ray spectrometry of sources with standardised activity. The sources were prepared quantitatively on glass discs by drop deposition of a solution with Ac in radioactive equilibrium with its daughter nuclides. Their activity was measured by a primary standardisation technique based on alpha-particle counting at a defined low solid angle.

Measurement of absolute γ-ray emission probabilities in the decay of U.

Accurate measurements were performed of the photon emission probabilities following the α decay of U to Th. Sources of highly enriched U were characterised in terms of isotopic composition by mass spectrometry and their activities were standardised by means of alpha-particle counting at a low defined solid angle. The standardised sources were subsequently measured by high-resolution γ-ray spectrometry with calibrated high-purity germanium detectors to determine the photon emission probabilities.

Emission probability measurement of γ- and X- rays in Ra-226 and Pb-210 decay.

The emission intensities of 186.21keV, 46.54keV, XL(Bi) and XK(Rn) photons were measured with calibrated HPGe detectors.

(60)Co in cast steel matrix: A European interlaboratory comparison for the characterisation of new activity standards for calibration of gamma-ray spectrometers in metallurgy.

Two series of activity standards of (60)Co in cast steel matrix, developed for the calibration of gamma-ray spectrometry systems in the metallurgical sector, were characterised using a European interlaboratory comparison among twelve National Metrology Institutes and one international organisation. The first standard, consisting of 14 disc shaped samples, was cast from steel contaminated during production ("originally"), and the second, consisting of 15 similar discs, from artificially-contaminated ("spiked") steel. The reference activity concentrations of (60)Co in the cast steel standards were (1.

Activity standardization, photon emission probabilities and half-life measurements of (177)Lu.

Activity standardization of (177)Lu and measurement of two nuclear parameters were done. Activity standardization of (177)Lu was done utilizing the 4πβ-γ coincidence method with a combined standard uncertainty of 0.28%.

Comparison of properties of digital spectrometer systems.

We have tested two digital spectrometer systems, the DSP 9660 and Lynx(®) modules, connected to a HPGe detector. Lynx(®) is a fully integrated 32K channel signal analyzer based on digital signal processing techniques, which offers advanced digital stabilization. The model DSP 9660 digitalizes the signal directly at a very high sampling rate.

Use of a Si(Li) detector as β spectrometer.

The aim of this work is to demonstrate the capability of a Si(Li) detector for the measurement of β spectra, despite the energy absorption in air and in the Be window. A simple source holder fixes the source on the symmetry axis at 3mm from the detector window. The β-sources are produced by evaporation on a plastic backing plate.

Disease activity is an important factor for indeterminate interferon-γ release assay results in children with inflammatory bowel disease.

Background: Interferon-γ release assay (IGRA) is widely used for screening of latent tuberculosis (TB) before and during biological therapy (BT). An indeterminate result of IGRA represents a limitation in the management of inflammatory bowel disease (IBD). Data on factors influencing IGRA results are scarce in children.

Activity measurement of gamma-ray emitters in aerosol filters exposed in Lithuania, in March-April 2011.

Two aerosol sampling stations in Lithuania were simultaneously used for assessing consequences of the accident at the Fukushima Dai-ichi nuclear power plant. The maximum activity concentrations of (129 m)Te, (131)I, (134)Cs and (137)Cs were 0.59 ± 0.

Calibration of stack monitors for measurement of noble gases in nuclear facilities.

In nuclear facilities stack monitors are used for the measurement of the volumetric activity of noble gases. Spectrometric measurement is needed because the content of stack effluents is always a mixture of radionuclides. In some nuclear power plants new types of monitors were installed based on HPGe detectors.

Correction of the TRUE summations in volume sources.

The correction factors for volume sources may be approximated using average efficiencies determined by experiment or by Monte Carlo methods in the same way as for point sources. This simple technique does not take into account properly the absorption of photons in the source, nor the change of the effective solid angle. A more precise method must take into account for the spatial distribution of products of efficiencies η(peak)*η(total) (for summing-out) or η(peak)*η(peak) (for summing-in) over the volume of the source.

Standardization, decay data measurements and evaluation of 64Cu.

The purposes of this study were to create national activity standards of (64)Cu, to make possible the definition of an international key comparison reference value and to determine the decay data in order to improve the decay scheme. Four laboratories measured the activity of a (64)Cu solution; these results were compared through the International Reference System. Moreover, the laboratories carried out new measurements of the photon emission intensities and of the half-life.

International exercise on 124Sb photon emission intensities determination.

An international exercise, registered as EUROMET project no. 907, was launched to measure both the activity of a solution of (124)Sb and the photon emission intensities of its decay. The same solution was sent by LNE-LNHB to eight participating laboratories, six of which sent results for photon emission intensities both in absolute and in relative terms.

International exercise on 124Sb activity measurements.

An international exercise, registered as EUROMET project no. 907, was launched to measure both the activity of a solution of (124)Sb and the photon emission intensities of its decay. The same solution was sent by LNE-LNHB to eight participating laboratories.

Intercomparison of methods for coincidence summing corrections in gamma-ray spectrometry.

A comparison of the coincidence summing correction methods is presented. Since there are several ways for computing these corrections, each method has advantages and drawbacks that could be compared. This part of the comparison was restricted to point sources.

Total efficiency of GE detectors--dead layer signal effect.

Two types of detectors (GC 4018 and BE 5030) were compared regarding the signal from the outer dead layer of the detector. Gamma-spectra of Am-241 were acquired with various delays against the starting signal from an alpha LS probe. Coincidence spectra from both detectors were different.

The new IAEA-372 grass-certified reference material for (40)K and (137)Cs.

A new grass-certified reference material characterized for (137)Cs and (40)K has been issued by the International Atomic Energy Agency. Characterization of this material was conducted by a group of national metrological institutes and expert laboratories. The paper describes the process for assigning the certified reference value to the material.

Gaseous standards preparation with the radionuclide Ar-41 for stack monitors calibration and verification in nuclear facilities.

The Czech Metrology Institute performs calibration and verification of noble gases stack monitors in nuclear power plants and nuclear research facilities. Together with Kr-85 and Xe-133, the radionuclide Ar-41 is measured using HPGe detectors and its activity is determined using a gamma-ray peak at 1293keV. The counting efficiency used in these measurements was calculated by the Monte Carlo method using the MCNP code.

Determination of emission probabilities of gamma photons in the decay of (56)Co.

The emission probabilities of gamma photons in the decay of (56)Co were determined at Czech Metrology Institute (CMI) by means of an HPGe detector. This detector was calibrated experimentally and by MCNP-computation in the energy range from 40 to 2754keV for a point source geometry and source-to-detector distance of 25cm. Experimental and computed peak and total efficiencies were compared and calibration curves were determined.

Experimental and MC determination of HPGe detector efficiency in the 40-2754 keV energy range for measuring point source geometry with the source-to-detector distance of 25 cm.

A precise model of a 40% relative efficiency p-type HPGe detector was created for photon detection efficiency calculation using the MCNP code. All detector parameters were determined by different experiments. No experimental calibration points were used for the modification of detector parameters.

Testing of properties of digital modules used in gamma-ray spectrometry.

The properties of digital modules (analog-to-digital converters (ADC), digital signal processor (DSP)) in spectrometric chain are the decisive factors which affect the quality of spectrometric measurements. Several properties, integral and differential linearity, channel profiles and throughput, of various ADC and DSP models by CANBERRA were tested.