Grant: Subatomic Physics Envelope - Project

Mysterious subatomic particles known as neutrinos are still not fully understood. A recent and controversial experiment at the world's largest nuclear physics laboratory CERN (located near Geneve) has reported that neutrinos may travel faster than the speed of light, exceeding nature's cosmic speed limit. The character of massive neutrinos is one of the most puzzling questions in physics. The possibility of observing a special kind of decay, called neutrinoless double-beta decay (0nußß), offers scientists the chance to gain insight into the mysterious nature of neutrinos. Although this decay process has yet to be observed, many low-counting rates experiments are being conducted worldwide in underground laboratories to address this problem. If the 0nußß decay is observed, detailed knowledge of the underlying nuclear structure will be required to determine the mass of the neutrino from the half-life of the 0nußß decay. The nuclear transition is described by a special term called the nuclear matrix elements (NME), that is calculated theoretically. These calculations can be tested using the 2nußß decay mode. Not only can the NME be extracted from the 2nußß decay, but part of the NME can be inferred from the electron capture (EC) decay branches of the several nuclei in ßß decays. The TITAN-EC project measures the EC branching ratios in a set of special nuclei involved in ßß decay. This experimental input is essential to test theoretical nuclear models. The experiments will be carried out by an international collaboration using the TITAN ion trap facility at TRIUMF, Canada's Nuclear and Particle Physics Laboratory (Vancouver, BC). The proposed research builds on work funded by a previous NSERC project, where proof-of-principle measurements and major experimental improvements were accomplished and published. The proposed next stage of the TITAN-EC collaboration will capitalize on the recent investments, and will move into modus operandi, performing the high-priority experiments already approved at TRIUMF.