Technical note: On the reliability of laboratory beta-source calibration for luminescence dating

The dose rate of the 90Sr / 90Y beta source used in most luminescence readers is a laboratory key parameter. There is a well-established body of knowledge about parameters controlling accuracy and precision of the calibration value but some hard-to-explain inconsistencies still exist. Here, we have investigated the impact of grain size, aliquot size and irradiation geometry on the resulting calibration value through experiments and simulations. The resulting data indicate that the dose rate of an individual beta source results from the interplay of a number of parameters, most of which are well established by previous studies. Our study provides evidence for the impact of aliquot size on the absorbed dose in particular for grain sizes of 50–200 µm. For this grain-size fraction, the absorbed dose is enhanced by ∼ 10 %–20 % as aliquot size decreases due to the radial increase of dose rate towards the centre of the aliquot. The enhancement is most variable for 50–100 µm grains mounted as aliquots of < 8 mm size. The enhancement is reversed when large grains are mounted as small aliquots due to the edge effect by which the dose induced by backscattered electrons is reduced. While the build-up of charge dictates the increase of absorbed dose with the increase of grain size, this principle becomes more variable with changing irradiation geometry. We conclude that future calibration samples should consist of subsamples composed of small, medium, large and very large quartz grains, each obtaining several gamma doses. The calibration value measured with small, medium and large aliquots is then obtained from the inverse slope of the fitted line, not from a single data point. In this way, all possible irradiation geometries of an individual beta source are covered, and the precision of the calibration is improved.

Исследование радиационной эрозии в газоразрядном детекторе с помощью атомно-силовой микроскопии

Using Atomic Force Microscopy Methods, we studied the samples of the cathodes of multiwire proportional chambers after long-term irradiation with a beta-source 90Sr at the longevity test. The changes in the morphology of the copper foil surface at the cathode of the detector as a result of the influence of the electron flow are described. It is presented a quantitative assessment and analysis of the evolution of the resulting radiation defects depending on the irradiation conditions. It is shown the similarity of the radiation defects in the laboratory prototypes and in full scale proportional chambers that have been operated at the LHC for almost 10 years.

The Self-Absorption Effect of Ni-63 Beta Source to the Silicon Carbide based Betavoltaic Battery

A typical planar structure is the most feasible conceptual design of betavoltaic battery due to its simplicity. The self-absorption of beta source, however, causes a limitation to the geometrical efficiency. Herein, we tried to investigate the self-absorption event in Ni-63 beta source by changing the geometrical aspects and evaluated its effect on each layer of a 4H-SiC semiconductor as the radiation-electricity converter. The design configuration from previous literature was adopted and the model was developed using Monte Carlo N-Particle X (MCNPX) consists of radioisotope source, semiconductor, and also ohmic contacts. The energy of beta emission was adjusted to the actual Ni-63 beta spectra with an isotropic distribution of ejected particles. The average beta energy deposition degrades along with the addition of source mass thickness, but the n+ substrate has a unique result where a peak is observed at 0.1246 mg/cm2 due to the self-absorption effect. Furthermore, the rectangular surface area magnification gives a positive impact on the beta energy deposition up to 2.48% and the photon average energy deposition up to 137.21%. The results of average electron absorbed dose are consistent with Oldano-Pasquarelli semi-empirical theory of self-absorption in the beta source, where the upper layer receives a wider angular distribution of particles compared to the lower one, which corresponds to the counting geometrical coefficients.

Technical note: On the reliability of laboratory beta-source calibration for luminescence dating

The dose rate of the 90Sr / 90Y beta source used in most luminescence readers is a laboratory key parameter. There is a well-established body of knowledge about parameters controlling accuracy and precision of the calibration value but some hard to explain inconsistencies still exist. Here we have investigated the impact of grain size, aliquot size and irradiation geometry on the resulting calibration value through experiments and simulations. The resulting data indicate that the dose rate of an individual beta source results from the interplay of a number of parameters, most of which are well established by previous studies. Our study provides evidence for an additionally complicating parameter which is aliquot size in particular for grain sizes of 50–200 μm. For this grain-size fraction the absorbed dose is enhanced by ~10–20 % as aliquot size decreases. This enhancement is most variable for 50–100 μm grains mounted as aliquots of