Efficient liquid scintillator loaded with a light-emitting conjugated oligomer for beta- and gamma-ray spectroscopic measurements

Abstract

Liquid scintillation (LS) counting is a common way to detect and measure radioactivity because it has a better time resolution and can discriminate between neutrons and gamma rays. We show how to make a promising liquid scintillator with a light-emitting conjugated oligomer: 9,9,9′,9′,9″,9″-hexakis(octyl)-2,7′,2′,7″-trifluorene (ADS038FO or 9HOTF). A container with a LS blend coupled with a photomultiplier detector setup showed enhanced scintillation for different radioactive sources. The gamma and beta radiation responses of LS were studied under various radiation sources: 137Cs, 60Co, and 22Na as gamma rays and 90Sr as a beta source. We observed a scintillation count increase with an increase in the percentage of 9HOTF. Further studies were performed to evaluate the characteristics of the fabricated liquid scintillator, such as emission wavelength, absorption, Compton edge (CE), and count rate. CE spectra were used to calibrate the energy, and the pulse height spectra were measured for the prepared LSs. The energy linearity was investigated, and the fabricated LSs showed more than 99% energy linearity. According to the results, the CE determined was more than 90% of the theoretical values for the 137Cs, 60Co, and 22Na sources. For the 90Sr/90Y beta source, the pulse height spectrum's lower energy (90Sr) and the higher energy (90Y) were distinguishable. The comparison between POPOP and 9HOTF-based LS proved that the performance of 9HOTF was marginally better than that of POPOP.