Precise determination of photon emission probabilities for the main X- and gamma-rays of 226Ra in equilibrium with daughters.

Within the context of a joint project between VNIIM (D.I. Mendeleyev Institute for Metrology) and LNHB (Laboratoire National Henri Becquerel), special 226Ra sources were prepared by VNIIM in order to determine as accurately as possible the absolute photon emission probabilities for the main X- and gamma-rays following the decay of 226Ra and daughters. The main purpose of this work was to supplement a previous joint study by Laboratorio Nacional de Metrologia das Radiaçoes Ionizantes (LNMRI) and LNHB to determine their relative values. Some specific point sources were produced for alpha-spectrometry measurements that were undertaken at VNIIM and also for gamma-ray spectrometry studies at VNIIM and LNHB. The 226Ra activity for the gamma-spectrometric sources was measured relative to the alpha-spectrometric sources by comparing the counts of the main gamma-rays. The total uncertainty of the activity for these sources was 0.2% (k = 1). Using calibrated germanium detectors, several X- and gamma-ray spectra were analyzed to determine the absolute photon emission probabilities of 226Ra in radioactive equilibrium with daughters. The results are presented and compared to other published values.

A source for measurement of the absolute intensities of 226Ra gamma-radiation in equilibrium with decay products.

The design and production techniques of a gamma-ray spectrometric source of 226Ra in equilibrium with its daughter decay products have been developed. The radon emanation coefficient of the source did not exceed 0.1%. The 226Ra activity in the gamma-ray spectrometric source was measured relative to that in an alpha-particle spectrometric source by comparison of the intensities of the main gamma rays using a semiconductor gamma-ray spectrometer. The total uncertainty of the activity measurement results was 0.5% for a coverage factor of k = 2.

Study of XK and gamma photon emission following decay of 154Eu.

A joint project has been established between VNIIM (D.I. Mendeleyev Institute for Metrology) and LNHB (Laboratoire National Henri Becquerel) to determine as accurately as possible the X- and gamma-ray emission probabilities of 154Eu. Point sources were prepared by VNIIM, and absolute measurements of activity per unit mass were undertaken by both laboratories using coincidence, anti-coincidence and 4pi-gamma counting methods. Other point sources and one aliquot were also prepared for precise gamma-ray spectrometry measurements. Absolute photon emission probabilities were determined with a maximum uncertainty of 0.5% for the most intense lines, supporting the development of this nuclide as a multigamma standard.