Ludmil Tsankov

Pilot Study of the Application of Plastic Scintillation Microspheres to Rn-222 Detection and Measurement

This work demonstrates that when plastic scintillation microspheres (PSms) synthesized from polystyrene are exposed to 222Rn in air or water, they concentrate 222Rn in their volume. A theoretical model, based on the solution of the diffusion equation is developed, in order to describe the 222Rn sorption and desorption processes in PSms. A macroscopic quantity termed “sampling efficiency” is used to quantify the absorption properties of the PSms. The sampling efficiency is estimated by exposure of PSms to 222Rn in air and water. Estimates of the counting efficiency for measurement of the exposed PSms by commercial scintillation counters are presented. The results show that polystyrene PSms are simultaneously good samplers and detectors of 222Rn. These properties indicate that sensitive approaches for the measurement of 222Rn based on absorption and scintillation counting of PSms can be developed.

Light pulse generator for multi-element scintillation detectors testing

This paper discusses the key characteristics and the specific requirements for light pulse generators for testing multi-element scintillation detectors. A prototype of such a generator has been built and studied. The block diagrams and the schematics of the LED amplitude drivers of its individual channels are presented. Some key signals obtained with the light pulse generator are also shown.

Synthesis and characterisation of scintillating microspheres made of polystyrene/polycarbonate for 222 Rn measurements

Several studies have demonstrated that polycarbonate-based polymers have good capacities for the absorption of 222Rn. Meanwhile, polystyrene polymers are reported to be the most appropriate for developing plastic scintillator materials for the detection of radioactivity. The objective of this work was to develop plastic scintillators in the form of microspheres (PSm) composed of polystyrene and polycarbonate that could be used to measure 222Rn and improve this performance thanks to the combination of characteristics of both polymers. Our results show that PSm of polystyrene and polycarbonate can be made via the evaporation/extraction method, despite the two polymers not being miscible. From the point of view of the radioactive measurements, we observed that the addition of polycarbonate causes quenching, although it does not significantly affect the detection efficiency for alpha and high-energy beta emitters. From the point of view of 222Rn absorption, we observed that synthesis of the PSm through the evaporation/extraction method changes the 222Rn absorption of the raw material. This result demonstrates that the method of production of the polymer and the resulting physical characteristics are a key parameter for its final 222Rn absorption properties.

A test system for the front-end electronics of the PADME charged particle detector system

The PADME charged particle detector system aims to detect positrons and electrons with efficiency better than 99 % and time resolution below 1 ns. The system hosts about 200 readout electronics channels whose operation has to be verified and commissioned. A custom based test system allowing performing qualitative check of the detector and the front-end electronics has been developed. The initial tests and the performance of the front-end electronics are described and discussed. Time resolution better than 400 ps was achieved.

Electronic circuits for the high voltage supply and additional sensors for the polyphemus 222 Rn in soil-gas scintillation detector

A microcontroller system for managing the high voltage supply of a plastic scintillation detector for continuous in situ monitoring of the 222Rn concentration in soil gas is developed and tested. Additional sensors are provided to the system to follow up some ambient parameters (atmospheric pressure, temperature, relative humidity and 3D acceleration)