Temperature quenching in LAB based liquid scintillator

Abstract

The effect of temperature changes on the light output of LAB based liquid scintillator is investigated in a range from −5 to 30 • C with α-particles and electrons in a small scale setup. Two PMTs observe the scintillator liquid inside a cylindrically shaped aluminum cuvette that is heated or cooled and the temperature dependent PMT sensitivity is monitored and corrected. The α-emitting isotopes in dissolved radon gas and in natural Samarium (bound to a LAB solution) excite the liquid scintillator mixtures and changes in light output with temperature variation are observed by fitting light output spectra. Furthermore, also changes in light output by compton electrons, which are generated from external calibration γ -ray sources, is analysed with varying temperature. Assuming a linear behaviour, a combined negative temperature coefficient of (−0.29 ± 0.01) %/ • C is found. Considering hints for a particle type dependency, electrons show (−0.17 ± 0.02) %/ • C, whereas the temperature dependency seems stronger for α-particles, with (−0.35 ± 0.03) %/ • C. Due to a high sampling rate, a pulse shape analysis can be performed and shows an enhanced slow decay component at lower temperatures, pointing to reduced non-radiative triplet state de-excitations.

A liquid scintillator for a neutrino Detector working at -50 degree

“…The light yield of Linear Alkylbenzene (LAB) based LS was found to increase ∼ 0.3% per degree in average from room temperature to -40 • C [15]. A similar result was also reported in another study from 30 • C to -5 • C [16]. However, all these studies focus on reducing thermal quenching, thus increasing the light yield of LS, with small samples.…”

Development, characterisation, and deployment of the SNO+ liquid scintillator

“…Additionally, the quenching of the scintillator cocktail has a temperature dependence that varies based on the particle type [28]. These measurements have been corroborated through multiple other studies [29,30].…”

“…Recent measurements of the Birks' constant are in the range of 0.0066 ± 0.0016 to 0.0076 ± 0.0003 cm/MeV for -particles [24], 0.0094 ± 0.0002 to 0.0098 ± 0.0003 cm/MeV for protons [25], and ∼ 0.0074 cm/MeV for electrons [26]. Additionally, the quenching of the scintillator cocktail has a temperature dependence that varies based on the particle type [27]. These measurements have been corroborated through multiple other studies [28,29].…”

Neutrino Physics with an Opaque Detector

“…No timing information has been used and more sophisticated spatial reconstruction techniques could likely improve the e − vs. γ separation further. [18]. The measurements from the prototype obtained with the opaque formulations are compared with those from the transparent scintillator (red), which serves as a control sample.…”

“…The high (dark blue) and low (light blue) opacity formulations are obtained by mixing in a paraffin polymer at 10% and setting the temperature at 12 • C and 26 • C, respectively. Studies of an LAB-based scintillator showed only percent-level effects on the light yield from a similar temperature change[18]. The measurements from the prototype obtained with the opaque formulations are compared with those from the transparent scintillator (red), which serves as a control sample.…”