Nuvia (Czechia)

Many international low-background experiments are showing increasing interest in the use of different plastic scintillation detectors. Based on our experience in the field of quality improvement of the polystyrene (PS) based plastic scintillation detectors, this work is focusing on a further enhancement of the scintillator light output and the associated energy resolution crucial for the detection of a very rare nuclear processes. To produce PS scintillators from liquid styrene various stabilization additives and conditions of polymerization process are commonly used. These factors, i.e. stabilization additives and atmospheric oxygen, have a negative impact on above mentioned optical properties of the scintillation detectors. Within this study, several samples under different conditions, e.g. concentrations of luminescent additives; presence of stabilization additives; air and inert atmosphere, were prepared and tested using a unique tunable electron spectrometer providing a monoenergetic electron beam ranging from 200 keV to 1.5 MeV.

The work deals with the comparison of voltage dividers with different wiring of resistors and capacitors. The voltage divider recommended by the manufacturer of the used photomultiplier (ET Enterprises, GB) was used as a reference. The aim was to assess the influence of different voltage dividers together with the large volume scintillation detector on detection parameters such as the efficiency of the measurement and dose rate linearity using 241Am, 137Cs, and 60Co gamma sources. The experiments showed relatively great differences between 15_10(_C) voltage divider (R1 and R2-R11, 15 MW and 10 MW) and the rest. Furthermore, it was confirmed that the voltage divider recommended by the manufacturer of the used photomultiplier showed the best results, but some of the measured dividers exhibited similar results and therefore can be used in radiation portal monitors as well.

The discovery of scintillation in the blue regime from poly(ethylene naphthalate) (PEN), a commonly used high-performance industrial polyester plastic, has sparked the interest of the physics community as a new type of plastic scintillator material. This observation in addition to its good mechanical and radiopurity properties makes PEN an attractive candidate as an active structure scintillator for low-background physics experiments. This paper reports on investigations of its potential in terms of production tests of custom made tiles and various scintillation light output measurements. These investigations substantiate the high potential of usage of PEN in low-background experiments.