Double Beta Decay
Measuring the Mass of the Neutrino
One of the most elusive and exotic subatomic particles being investigated around the world today is the neutrino. Understanding the family of neutrino particles and how they interact with other matter (and among themselves) has become one the most intensive physics research efforts ever attempted by mankind.
With a virtually undetectable mass, and without electric charge, these weakly interacting particles have been devilishly difficult to measure. They can travel through a light year of solid lead without interacting, and they have been recently shown to "oscillate" from one neutrino flavor to another. Most of the neutrino searches involve enormous detectors in deep underground cavities.
Two groups of researchers are fielding substantially different devices at WIPP that attempt to make the neutrino mass measurement. Research collaborators including Pacific Northwest National Laboratory (PNNL) and Los Alamos are developing the Majorana Project which will use solid state semiconductors to make the measurement. In contrast, collaborators lead by Stanford University have designed a detector called the Enriched Xenon Observatory (EXO) which will use a special pressurized chamber of the rare gas Xenon to make the measurement.