After 11 years, the Main Injector Neutrino Oscillation Search (MINOS) experiment and its second iteration, MINOS+, in the upgraded NuMI neutrino beamline, have concluded their runs. A significant forerunner to DUNE, MINOS was the first Fermilab experiment to shoot a beam of neutrinos through two massive detectors spaced hundreds of miles apart.
The NOvA experiment, currently operating, was designed as the successor to MINOS, and DUNE will spearhead future cutting-edge neutrino research. Many of MINOS’ more than 200 collaborators are moving on to these and other neutrino experiments.
MINOS’ notable accomplishments include a highly precise measurement of the mass-squared difference parameter. The detector’s built-in magnet enabled the experiment to distinguish neutrino and antineutrino interactions event by event, a capability that separated MINOS from all other neutrino experiments of its generation. MINOS studied neutrino and antineutrino oscillations separately, and it set stringent constraints for sterile neutrinos. MINOS also made early competitive measurements of electron appearance, and determined that the mass-squared difference of a neutrino and its antineutrino counterpart are the same, as predicted by theory.
MINOS’ second phase, MINOS+, began in 2013. The higher-energy neutrinos from the powerful NuMI beam enabled MINOS+ to investigate a different energy region and to paint a more complete picture of neutrino oscillation.
In 2014, MINOS/MINOS+ combined its various data sets from disappearance and appearance data, as well as from atmospheric and beam data, thereby helping to launch the era of precision neutrino physics analyses using a full three-neutrino model.
“With its strong oscillation signal, MINOS solidly excluded alternative interpretations and gave precise measurements of the main parameters involved in neutrino disappearance,” said Rob Plunkett, co-spokesperson of the experiment from 2006 to 2014. “MINOS was also a major player in the uncovering of large electron neutrino appearance, the phenomenon that underlies the DUNE program.”