The Rayleigh ratio measurement for SNO+ liquid scintillator and background studies of the internal ropes
Abstract
As a successor of the Sudbury Neutrino Observatory, the SNO+ experiment is planned
to start data taking in early 2013. Making use of the liquid scintillator, Linear
Alkylbenzene (LAB), the SNO+ experiment aims to perform ux measurements of
low energy solar neutrinos in one phase, and wait for neutrinoless double beta decay
events in another phase where 44 kg of natural Neodymium would be added into
LAB.
The Rayleigh ratio of LAB was found to be 16.60 _ 3.14 _106 cm1 at 546
nm using the relative measurement technique. The wavelength dependency of the
Rayleigh scattering was also examined and compared with the theoretical prediction.
A setup which is usable to measure the angular dependency of the Rayleigh scattering
was built, and an isotropic behaviour of the scattering was tested. The _ and
backgrounds, due to the internal calibration ropes situated in the scintillator volume,
were studied using the SNO+ Monte Carlo Package. Also, the amount of 210Pb
originating from the internal calibration ropes due to the intrinsic contamination of
238U, Rn emanation and plated on the surface prior to the installation were assessed
to examine if it is a tolerable level to achieve the target level of 13.4 background
events per day.