Purification of liquid scintillator and Monte Carlo simulations of relevant internal backgrounds in SNO+

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Quirk, Sarah Elizabeth
The SNO+ experiment has begun research and development to engineer replacing the heavy water in the Sudbury Neutrino Observatory with liquid scintillator in order to study low energy solar neutrinos, double beta decay, and many other exciting physics topics. Experimentation and simulation have been combined to evaluate the purification of the liquid scintillator, linear alkylbenzene, for the SNO+ pro ject. Four radiopurification methods were tested: water and acid extraction, adsorption and distillation. The combination of adsorption and distillation yielded the best results with a reduction factor of 10000. Optical purification tests showed that double distillation and the combination of adsorption and distillation provided the best method of removing optical impurities from the liquid scintillator. Simulation studies showed that it is necessary to minimize internal radioisotopes: 210 Bi, 210 Pb, uranium chain, thorium chain, and 40 K in order to achieve desired uncertainty levels in the measurement of the pep solar neutrino signal.
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