Universal calibration of a scintillation spectrometer with a NaI(Tl) detector when measuring 137Cs activity in counting samples of arbitrary density and volume

The article proposes an empirical method for constructing a universal calibration for a scintillation gamma spectrometer, which allows determining the activity and specific activity of 137Cs with an accuracy of no more than 15% in counting samples of arbitrary density and volume in cylindrical containers with a volume of 250 ml and 500 ml. To construct calibration ratios, measurements of 137Cs sample media prepared on the basis of materials of different densities (quartz sand, plastic granules and sawdust) were performed. The calibration was carried out by preparing samples from the listed materials with a volume of 50 to 250 ml in increments of 50 ml for a 250 ml container and 100-500 ml in increments of 100 ml for a 500 ml container. Along with taking into account the volume of the counting sample, its weighing was also carried out. The result of the measurements performed for each material was the ratio of the activity of the counting sample to the counting intensity in the 137Cs window, depending on the volume. The universal calibration factor is obtained by taking into account the counting rate from the mass and volume of the sample for the corresponding measuring vessel.

Application of laboratory beta radiometry for quantitative indication of radionuclide concentration in plant samples

The aim is to improve the beta-radiometric method of quantitative indication of the content of 90Sr and 137Cs in the counters of plant samples. Material and methods. In the Chernobyl exclusion zone (ChEZ) in 2017, 2019, leaves of silver birch, black poplar, common reed, sedge were selected, which were dried, crushed, and used as calculating samples for beta radiometry and spectrometry. For measurements, a combined KRK-1 radiometer and a SEB 01-150 spectrometer beta-radiation energy were used. Results. Currently, in plant samples from the ChEZ, the following are widespread: natural 40K, the concentration of which is usually less than 1 % in relation to the concentration of technogenic radionuclides 90Sr+90Y and 137Cs, therefore, when measuring 90Sr and 137Cs, beta radiation of 40K can be ignored. The measurements were carried out without a spectral filter and using a thin molybdenum filter. Without filter – show the count rate of 90Sr+90Y and 137Cs radiation. The filter transmits 2–3.5 % of the low-energy beta radiation of 90Sr and 137Cs and more than 95 % of the high-energy 90Y. The ratio of the count rate of 90Y pulses with and without filter is 2.14. The 90Sr concentration in the samples was determined from the results of measurements of 90Y, and 137Cs – through the fraction of the counting rate, which remains after deducting 90Sr+90Y. Comparison of the concentration of radionuclides measured by the method of beta-radiometry and spectrometry showed no significant difference between the results obtained by the two methods. Conclusions. The beta radiometry method for 90Sr and 137Cs provides for measuring the counting rate of beta radiation from counting samples without a spectral filter and using a thin molybdenum filter. Based on the research results, a procedure for calculating the concentration of 90Sr and 137Cs in counting samples of plant leaves was developed

Photoluminescence and scintillation characteristics of Bi-loaded PVK-based plastic scintillators for the high counting-rate measurement of high-energy X-rays

Bi-loaded PVK-based plastic scintillators doped with bis-MSB are applicable for high counting-rate measurement of high-energy X-rays. They showed a higher detection efficiency and light yield than EJ-256 under 67.41 keV X-ray irradiation.

SATELLITE OBSERVATIONS OF EFFECTS OF AURORAL IONOSPHERE HEATING WITH THE EISCAT FACILITY

The measurements are presented of the dynamics of energetic electrons on the Meteor-M No. 2 orbit during the experiment on the ionosphere heating by strong shortwave radiation with the EISCAT heating facility (Tromso, Norway) on October 12, 2018. It is revealed that the counting rate of electrons with energy >40 keV increased by five times in 30 s after the moment of the facility switch-off, and sharp (by 3–4 times) short counting rate peaks were registered as compared to the background. The peaks were repeated approximately every 6 seconds. The results of observations of variations in total electron content of the high-latitude ionosphere reconstructed from ionospheric delays of GLONASS R21 satellite signals during the same heating experiment are also presented. The analysis of these data revealed small exceeding of TEC values over the trend at the boundary of the heating area.

LOW ENERGY NEUTRINOS AS THE CAUSE OF ANOMALIES IN BETA DECAYS AND COLD NUCLEAR TRANSMUTATIONS

In a number of experiments, when registering particles emitted in beta decays, periodic fluctuations in the counting rate with an amplitude of up to tenths of a percent of the average value were detected, and short bursts were found that significantly exceed the usual counting rate. These anomalies can be comprehensively explained by the participation of extremely low-energy cosmic neutrinos in beta decays. The assumption that neutrino-antineutrino pairs are generated by collisions of matter particles during thermal motion allows us to find approaches to explaining the phenomenon of cold nuclear transmutations. Experiments proving this hypothesis are described.

Photon Counting Imaging with Low Noise and a Wide Dynamic Range for Aurora Observations

The radiation intensity of observed auroras in the far-ultraviolet (FUV) band varies dramatically with location for aerospace applications, requiring a photon counting imaging apparatus with a wide dynamic range. However, combining high spatial resolution imaging with high event rates is technically challenging. We developed an FUV photon counting imaging system for aurora observation. Our system mainly consists of a microchannel plate (MCP) stack readout using a wedge strip anode (WSA) with charge induction and high-speed electronics, such as a charge sensitive amplifier (CSA) and pulse shaper. Moreover, we constructed an anode readout model and a time response model for readout circuits to investigate the counting error in high counting rate applications. This system supports global rates of 500 kilo counts, 0.610 dark counts s−1 cm−2 at an ambient temperature of 300 K and 111 µm spatial resolution at 400 kilo counts s−1 (kcps). We demonstrate an obvious photon count loss at incident intensities close to the counting capacity of the system. To preserve image quality, the response time should be improved and some noise performance may be sacrificed. Finally, we also describe the correlation between counting rate and imaging resolution, which further guides the design of space observation instruments.

Counting-loss correction method based on dual-exponential impulse shaping

Under the condition of high counting rate, the phenomenon of nuclear pulse signal pile-up using a single exponential impulse shaping method is still very serious, and leads to a severe loss in counting rate. A real nuclear pulse signal can be expressed as a dual-exponential decay function with a certain rising edge. This paper proposes a new dual-exponential impulse shaping method and shows its deployment in hardware to test its performance. The signal of a high-performance silicon drift detector under high counting rate in an X-ray fluorescence spectrometer is obtained. The result of the experiment shows that the new method can effectively shorten the dead-time caused by nuclear signal pile-up and correct the counting rate.