Neutrinoless Double Beta Decay

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The Enriched Xenon Observatory is an experiment in particle physics aiming to detect "neutrino-less double beta decay" using large amounts of xenon isotopically enriched in the isotope 136. A 200-kg detector using liquid Xe is currently being installed at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico. Many research and development efforts are underway for a ton-scale experiment, with the goal of probing new physics and the mass of the neutrino. The Enriched Xenon Observatory

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Feynman diagram of neutrinoless double-beta decay, with two neutrons decaying to two protons. The only emitted products in this process are two electrons, which can only occur if the neutrino and antineutrino are the same particle (i.e. Majorana neutrinos) so the same neutrino can be emitted and absorbed within the nucleus. In conventional double-beta decay, two antineutrinos - one arising from each W vertex - are emitted from the nucleus, in addition to the two electrons. The detection of neutrinoless double-beta decay is thus a sensitive test of whether neutrinos are Majorana particles.

Neutrinoless double-beta decay experiments

Numerous experiments have been carried out to search for neutrinoless double-beta decay. Some recent and proposed future experiments include:

• Completed experiments:
  
  
  
  
  
  • Gotthard TPC
  • Heidelberg-Moscow
  • IGEX
  • NEMO1 and 2

• Current and proposed experiments
  
  
  
  
  
  • COBRA
  • CUORICINO and CUORE
  • EXO
  • GERDA
  • MAJORANA
  • MOON
  • NEMO-3 and SuperNEMO
  • SNO+

See:Direct Dark Matter Detection

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