White Paper on the Majorana Zero-Neutrino Double-Beta Decay Experiment

The objective of the Majorana Experiment is to study neutrinoless double beta decay (0nbb) with an effective Majorana-neutrino mass sensitivity below 50 meV in order to characterize the Majorana nature of the neutrino, the Majorana mass spectrum, and the absolute mass scale. An experimental study of the neutrino mass scale implied by neutrino oscillation results is now technically within our grasp. This exciting physics goal is best pursued using the well-established technique of searching for 0nbb of 76Ge, augmented with recent advances in signal processing and detector design. The Majorana Experiment will consist of a large mass of 76Ge in the form of high-resolution intrinsic germanium detectors located deep underground within a low-background shielding environment. Observation of a sharp peak at the bb endpoint will quantify the 0nbb half-life and thus the effective Majorana mass of the electron neutrino. In addition to the modest R&D program, we present here an overview of the entire project in order to help put in perspective the scope, the low level of technical risk, and the readiness of the Collaboration to immediately begin the undertaking.