This is a guest post composed as part of the NSF Science: Becoming the Messenger workshop, Lawrence KS January 27, 2011.
Neutrinos are tiny particles that pass through matter almost without a trace. Created in nuclear reactions such as those powering the sun and nuclear reactors, a mile of lead would stop only one neutrino in six trillion. This is great for studying anything hidden deep in matter, such as the core of the sun, buried radioactive elements in the Earth, distant supernova, possibly even mysterious dark matter. But some neutrino science projects are hampered by lack of knowledge about the neutrino itself. A new neutrino experiment has just begun taking data to answer one of the biggest unknowns about neutrinos. It is known that neutrinos come in three types, some more detectable than others at the energies typical of radioactive decay. It was discovered in 1990s and 2000s that neutrinos can transform in at least two ways between types. When they transform into less-detectable forms, they seem to “disappear”. In principle, there should be three ways neutrinos can transform. But an experiment at the Chooz nuclear power plant showed that this third transformation is either absent or weak. If the third transformation happens, it never affects more than 20% of reactor neutrinos. The new experiment, named “Double Chooz”, is designed to be up to 6 times more sensitive to this third neutrino mode. One of three international experiments designed to make this measurement, Double Chooz is the first to start taking data. Neutrino researchers planning future experiments are eagerly awaiting the results. -- Glenn Horton-Smith
