First results of the search of neutrinoless double beta decay with the NEMO 3 detector

TL;DR

The NEMO 3 detector conducted a search for neutrinoless double beta decay, setting new lower limits on half-lives and neutrino masses, but found no evidence of the decay after 389 days of data collection.

Contribution

First experimental results from NEMO 3 on neutrinoless double beta decay, establishing new half-life limits and neutrino mass constraints.

Findings

No evidence for neutrinoless double beta decay was observed.

Half-life lower limits are 4.6 x 10^23 years for 100Mo and 1.0 x 10^23 years for 82Se.

Effective Majorana neutrino mass limits are < 0.7-2.8 eV for 100Mo and < 1.7-4.9 eV for 82Se.

Abstract

The NEMO 3 detector, which has been operating in the Frejus underground laboratory since February 2003, is devoted to the search for neutrinoless double beta decay (bb0nu). Half-lives of the two neutrino double beta decays (bb2nu) have been measured for 100Mo and 82Se. After 389 effective days of data collection from February 2003 until September 2004 (Phase I), no evidence for neutrinoless double beta decay was found from ~7kg of 100Mo and ~1 kg of 82Se. The corresponding lower limits for the half-lives are 4.6 x 10^23 years for 100Mo and 1.0 x10^23 years for 82Se (90% C.L.). Depending on the nuclear matrix elements calculation, limits for the effective Majorana neutrino mass are <m> < 0.7-2.8 eV for 100Mo and <m> < 1.7-4.9 eV for 82Se