Evaluation of techniques for 0νββ0νββ-decay experiments, and prospects for direct observation

The data from neutrino oscillations yield values for neutrino mixing angles and squares of the differences of neutrino mass eigenvalues. These imply that if neutrinos are Majorana particles, the half-lives for neutrinoless double-beta 0νββ0νββ decay should be within the sensitivity of well-designed experiments. In this paper, some of the proposed experimental techniques will be analyzed using criteria that allow comparison of their relative merits. The target sensitivity of the physics reach of a one-ton scale experiment is defined as the ability to cover the inverted neutrino mass hierarchy.