The interest and relevance of next-generation 0, @-decay experiments is increasing. Even with nonzero neutrino mass strongly suggested by solar and atmospheric neutrino experiments sensitive to 6m2, 0, P&decay experiments are still the only way to establish the Dirac or Majorana nature of neutrinos by measuring the effective electron neutrino mass, (m,). In addition, the atmospheric neutrino oscillation experiments imply that at least one neutrino has a mass greater than about 50 meV. The Majorana Experiment expects to probe an effective neutrino mass near this critical value.
Majorana is a next-generation 76Ge double-beta decay search. It will employ 500 kg of Ge, isotopically enriched to 86% in "Ge, in the form of N 200 detectors in a close-packed array. Each crystal will be electronically segmented and each segment fitted with pulse-shape analysis electronics. This combination of segmentation and pulse-shape analysis significantly improves our ability to discriminate neutrinoless double beta-decay from internal cosmogenic s8Ge and 6oCo. The half-life sensitivity is estimated to be 4.2 x 10z7 y corresponding to a (m,) range of 5 20 -70 meV, depending on the nuclear matrix elements used to interpret the data.