New Veto System
For the last few decades liquid scintillators (LS) were used as the main detector target for a variety of experiments such as Borexino, DayaBay, SNO+ and the outer detector for LUX-Zeplin. Their large light yield, high optical transparency, and low toxicity combined with high flash point ensure safe operations at room temperatures and in challenging experimental environments such as underground experiments. Also handling and infrastructure is fairly straightforward compared to, for example, cryogenic experiments. Doping with suitable rare earths leads to the ability to optimize the scintillator for particular types of radiation. By adding a small amount of the Gadolinium (≈ 0.1%) into liquid scintillator, the thermal neutron capture efficiency can be greatly improved, enabling better detection efficiency on inverse beta decay and neutron background of the direct dark matter detector as well. Plastic scintillator (PS) however exhibits a better mechanical strength, is inexpensive to manufacture and less prone to aging. Traditionally, PS was used in the detection of high energy particles in collider or cosmic ray experiments due to their radiation tolerance. Good endurance to the environmental impacts (temperature, moisture) and mechanical deformation enable the PS to be worked under various environments such as vacuum systems.