EXO and the quest for Majorana Neutrino Masses

Event Date: 

Tuesday, April 30, 2013 - 4:00pm

Event Location: 

  • Broida 1640

Event Contact: 

Refreshments served at 3:40

Speaker:

Giorgio Gratta - Stanford University

With the definitive evidence for neutrino oscillations collected in the last decade, we now believe that neutrino masses are non-zero. Oscillation measurements, however, only measure mass differences and give us little information about the absolute values of neutrino masses.

The hypothetical phenomenon of neutrino-less double-beta decay can probe the neutrino mass scale with exquisite sensitivity. This process, if observed, would also imply that neutrinos, unlike all other spin-1/2 particles, have only two component wave functions and that lepton number is not a conserved quantity. Following the well known principle that there is no free lunch in life, interesting half-lives for neutrino-less double-beta decay exceed 10^25 years (or ~10^15 times the age of the Universe) making experiments rather challenging. I will describe the EXO program that is developing the tools to search for this rare decay and discuss the recent measurements by EXO-200 that recently discovered the 2-neutrino double-beta decay in 136Xe and substantially improved the limit on Majorana neutrino masses.