MiniBooNE is an experiment at Fermilab designed to observe neutrino oscillations (BooNE is an acronym for the Booster Neutrino Experiment). A neutrino beam consisting primarily of muon neutrinos is directed at a detector filled with 800 tons of mineral oil and lined with 1,280 photomultiplier tubes. An excess of electron neutrino events in the detector would support the neutrino oscillation interpretation of the LSND result.
History and motivation
Experimental observation of solar neutrinos and atmospheric neutrinos provided evidence for neutrino oscillations, implying that neutrinos have masses. Data from the LSND experiment at Los Alamos National Laboratory are controversial since they are not compatible with the oscillation parameters measured by other neutrino experiments in the framework of the Standard Model. Either there must be an extension to the Standard Model, or one of the experimental results must have a different explanation. Moreover, the KARMEN experiment in England examined a region similar to the LSND experiment, but saw no indications of neutrino oscillations. This experiment was less sensitive than LSND, and both could be right.
Cosmological data can provide an indirect but rather model-dependent bound to the mass of sterile neutrinos, such as the ms < 0.26 eV (0.44 eV) at 95% (99.9%) confidence limit given by Dodelson et al.. However, cosmological data can be accommodated within models with different assumptions, such as that by Gelmini et al.
MiniBooNE was designed to unambiguously verify or refute the LSND controversial result in a controlled environment. The first results came in late March 2007, and showed no evidence for muon neutrino to electron neutrino oscillations in the LSND region, refuting a simple 2-neutrino oscillation interpretation of the LSND results. More advanced analyses of their data are currently being undertaken by the MiniBooNE collaboration; early indications are pointing towards the existence of the sterile neutrino, an effect interpreted by some physicists to be hinting of the existence of the bulk or Lorentz violation. Some members of MiniBooNE have formed a new collaboration with outside scientists and proposed a new experiment (called MicroBooNE) designed to further investigate this.
^ S. Dodelson, A. Melchiorri, A. Slosar (2006). "Is cosmology compatible with sterile neutrinos?". Physical Review Letters 97: 04301. arXiv:astro-ph/0511500. Bibcode 2006PhRvL..97d1301D. doi:10.1103/PhysRevLett.97.041301.