The EXO detector acts as both a Time Projection Chamber (TPC) and a scintillation counter used to search for the neutrinoless double beta decay.  Such decays can only occur if neutrinos are their own anti-particle (Majorana) and a positive signal would provide a first measurement of the neutrino mass scale.   The Carleton EXO group members are involved in many aspects of the EXO experiment as members of the global  EXO collaboration.