Grant: Subatomic Physics Envelope - Research Tools and Instruments

Neutrinos, a fundamental component to the constituent matter of the universe, are similar to electrons but are many orders of magnitude lighter and have no electric charge. This makes neutrinos, of which there are three types, extremely difficult to detect and, although first experimentally discovered more than fifty years ago, their properties are still poorly understood. The recent measurements by SNO, SuperKamiokande, Kamland, and other experiments, have shown that neutrinos change flavour and have mass. These measurements are only sensitive to the difference of the squares of neutrino masses and the absolute mass scale is not yet known. Some of the most important remaining questions regarding neutrino properties include: What is the neutrino mass scale? How are the masses of the three known neutrinos ordered? Are neutrinos their own antiparticle? Discovery and precise measurement of neutrinoless double beta decay, the process in which two neutrinos in a nucleus simultaneously decay to two protons and two electrons, can provide answers to these questions. The hardware requested in this proposal will be utilized to develop detector technology that will lead to a sensitive search for the neutrinoless double beta decay of xenon 136 atoms. The requested hardware consists of a pressure vessel able to operate at pressures up to 10 bar and the internal components required to construct a gaseous xenon time projection chamber with a novel electroluminescence gain stage. The detector will be used to evaluate and optimize the energy resolution and tracking information of 1 MeV electrons. The longer-term goal is to scale up the technology first to a 200 kg xenon mass and ultimately to a multi-tonne detector.