Grant: Subatomic Physics Envelope - Research Tools and Instruments

Neutrinos are one of the most abundant particles in the universe, yet their critical properties, like their absolute mass, are unknown. Recent results from experiments like SNO, SuperKamiokande and Kamland have demonstrated that neutrinos have mass, but only the mass differences could be measured. Neutrinoless double beta decay offers a unique possibility to investigate for the mass amplitude and type. This process implies the simultaneous beta decays of two nucleons within a single atomic nucleus, with neutrinos interacting in a way that they do not leave the nucleus. This is only possible if neutrinos possess mass and special properties. The discovery of neutrinoless double beta decay would imply that neutrinos are their own anti-particles. This decay, if it exists, will be extremely rare and the very low background techniques developed by SNO will be essential to bring this search to success. The hardware requested in this proposal will be utilized to mitigate background in the EXO-200 detector which searches for neutrino-less double beta decay of xenon-136 nuclei and to calibrate the detector response to gamma rays, the principal source of background.