Influence of uniaxial pressure on dielectric properties of (1-x)Na0.5Bi0.5TiO3–xSrTiO3 for x = 0.01, 0.04, and 0.1 ceramics

The publication costs of this article were covered by the Estonian Academy of Sciences and the University of Tartu.The conventional solid-state sintering was applied to synthesized (1-x)Na0.5Bi0.5TiO3-xSrTiO3 (x = 0.01, 0.04, and 0.1) ceramics. Dielectric measurements of these ceramics were taken in the temperature range from 20 to 600 °C, in the frequency range from 1 kHz to 2 MHz and under uniaxial pressure ranging from 10 to 1100 bar. The study of the dielectric behaviour showed that the influence of uniaxial pressure on the investigated properties was considerable. The peaks εm gradually decreased and shifted towards lower temperatures with an increase of uniaxial pressure for all samples. The first effect developed with an increase of the strontium ion concentration. Experimental results revealed most interesting properties of the material in the context of its potential applications.Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Sr and stable strontium in bones of wild, herbivorous animals from Poland

Activity concentration of 90 Sr and stable strontium concentration was analysed in 42 samples of animal (deer, roe-deer, elk and boar) bones, which mostly originated from north-eastern Poland. Strontium separation was performed by extraction chromatography. Determination of chemical yield was controlled by means of stable Sr determination using atomic spectrometry at the beginning and at the end of the separation procedure. Equilibrated 90 Sr and 90 Y activity was measured using a liquid scintillator spectrometer. Stable strontium range was from 55.4±1.7 ppm to 91.8±4.5 ppm, the mean was 71.84 ppm with a standard deviation (SD) of 9.31 ppm. The mean recovery of strontium was 26.7% with SD = 16.1%. The maximum activity of 90 Sr, equal to 629±13 Bq/kg (ash) was found for a deer sample from Augustów Primeval Forest. In average, deer show the highest radiostrontium level, followed by roe-deer, elk and the lowest level were observed for boar. Differences between boar and deer or roe-deer are significant in terms of Kruskal-Wallis statistical test. Animal bones from north-eastern Poland showed about twice the mean concentration of 90 Sr, compared to those of south-central Poland, but the difference was found not significant. Activities observed in roe-deer bones suggest the deposition of a concentration of 1.9 to 3.5 kBq/m2 in the average of Chernobyl-origin 90 Sr in 1986 in north-eastern Poland

Preparation and Execution of the Electrical Quality Assurance Program On the LHC Superconducting Circuits During the Second Long Shutdown

The electrical quality assurance (ELQA) of the superconducting circuits of CERN’s Large Hadron Collider (LHC) during its second Long Shutdown (LS2) requires the execution of vast measurement campaigns. Each of 1658 electrical circuits as well as the instrumentation of each of the 1746 individual cryo-assemblies housing magnets, bus-bars and other components of the superconducting circuits, has to undergo a series of tests. At the beginning of the shutdown the tests are performed before and after the warm-up from cryogenic temperatures. The same tests are repeated at the end of the shutdown, this time before and after the cool-down. As part of the dipole bypass diode insulation consolidation project and due to the replacement of a few non-conform magnets, additional electrical tests and measurements had to be performed throughout the shutdown period. With each measurement, electrical parameters like resistance, complex impedance, and the quality of the insulation are verified and stored for future reference. Due to the many thousands of measurements to be performed, multiple automated mobile test benches had to be developed for the different test types along with dedicated database and analysis software applications for the documentation and follow-up of the test results and the non-conformities observed