MiniBooNE
Encyclopedia
Fermilab
Fermi National Accelerator Laboratory , located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics...
designed to observe neutrino oscillation
Neutrino oscillation
Neutrino oscillation is a quantum mechanical phenomenon predicted by Bruno Pontecorvowhereby a neutrino created with a specific lepton flavor can later be measured to have a different flavor. The probability of measuring a particular flavor for a neutrino varies periodically as it propagates...
s (BooNE is an acronym for the Booster
Tevatron
The Tevatron is a circular particle accelerator in the United States, at the Fermi National Accelerator Laboratory , just east of Batavia, Illinois, and is the second highest energy particle collider in the world after the Large Hadron Collider...
Neutrino
Neutrino
A neutrino is an electrically neutral, weakly interacting elementary subatomic particle with a half-integer spin, chirality and a disputed but small non-zero mass. It is able to pass through ordinary matter almost unaffected...
Experiment
Experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...
). A neutrino
Neutrino
A neutrino is an electrically neutral, weakly interacting elementary subatomic particle with a half-integer spin, chirality and a disputed but small non-zero mass. It is able to pass through ordinary matter almost unaffected...
beam consisting primarily of muon neutrino
Muon neutrino
The muon neutrino is a subatomic lepton elementary particle which has the symbol and no net electric charge. Together with the muon it forms the second generation of leptons, hence its name muon neutrino. It was first hypothesized in the early 1940s by several people, and was discovered in 1962 by...
s is directed at a detector filled with 800 tons of mineral oil
Mineral oil
A mineral oil is any of various colorless, odorless, light mixtures of alkanes in the C15 to C40 range from a non-vegetable source, particularly a distillate of petroleum....
and lined with 1,280 photomultiplier tubes
Photomultiplier
Photomultiplier tubes , members of the class of vacuum tubes, and more specifically phototubes, are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum...
. An excess of electron neutrino events
Event (particle physics)
An event in particle physics describes one set of particle interactions occurring in a brief span of time, typically recorded together. At modern particle accelerators this refers to the interactions that occur as a result of one beam crossing inside a detector....
in the detector would support the neutrino oscillation interpretation of the LSND
LSND
The Liquid Scintillator Neutrino Detector was a scintillation counter at Los Alamos National Laboratory that measured the number of neutrinos being produced by an accelerator neutrino source...
result.
History and motivation
Experimental observation of solar neutrinoSolar neutrino
Electron neutrinos are produced in the Sun as a product of nuclear fusion. By far the largest fraction of neutrinos passing through the Earth are Solar neutrinos....
s and atmospheric neutrinos provided evidence for neutrino oscillation
Neutrino oscillation
Neutrino oscillation is a quantum mechanical phenomenon predicted by Bruno Pontecorvowhereby a neutrino created with a specific lepton flavor can later be measured to have a different flavor. The probability of measuring a particular flavor for a neutrino varies periodically as it propagates...
s, implying that neutrinos have masses. Data from the LSND experiment
LSND
The Liquid Scintillator Neutrino Detector was a scintillation counter at Los Alamos National Laboratory that measured the number of neutrinos being produced by an accelerator neutrino source...
at Los Alamos National Laboratory
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...
are controversial since they are not compatible with the oscillation parameters measured by other neutrino experiments in the framework of the Standard Model
Standard Model
The Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles. Developed throughout the mid to late 20th century, the current formulation was finalized in the mid 1970s upon...
. Either there must be an extension to the Standard Model
Standard Model
The Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles. Developed throughout the mid to late 20th century, the current formulation was finalized in the mid 1970s upon...
, or one of the experimental results must have a different explanation. Moreover, the KARMEN experiment
KARMEN
KARMEN , a detector associated with the ISIS synchrotron at the Rutherford Appleton Laboratory...
in England examined a region similar to the LSND experiment, but saw no indications of neutrino oscillations. This experiment was less sensitive than LSND
LSND
The Liquid Scintillator Neutrino Detector was a scintillation counter at Los Alamos National Laboratory that measured the number of neutrinos being produced by an accelerator neutrino source...
, and both could be right.
Cosmological data can provide an indirect but rather model-dependent bound to the mass of sterile neutrino
Sterile neutrino
Sterile neutrinosIn scientific literature, these particles are also variously referred to as right-handed neutrinos, inert neutrinos, heavy neutrinos, or neutral heavy leptons . are a hypothetical type of neutrino that do not interact via any of the fundamental interactions of the Standard Model...
s, such as the ms < 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
Muon neutrino
The muon neutrino is a subatomic lepton elementary particle which has the symbol and no net electric charge. Together with the muon it forms the second generation of leptons, hence its name muon neutrino. It was first hypothesized in the early 1940s by several people, and was discovered in 1962 by...
to electron neutrino
Electron neutrino
The electron neutrino is a subatomic lepton elementary particle which has no net electric charge. Together with the electron it forms the first generation of leptons, hence its name 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
Sterile neutrino
Sterile neutrinosIn scientific literature, these particles are also variously referred to as right-handed neutrinos, inert neutrinos, heavy neutrinos, or neutral heavy leptons . are a hypothetical type of neutrino that do not interact via any of the fundamental interactions of the Standard Model...
, an effect interpreted by some physicists to be hinting of the existence of the bulk
Brane cosmology
Brane cosmology refers to several theories in particle physics and cosmology motivated by, but not exclusively derived from, superstring theory and M-theory.-Brane and 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.
External links
- MiniBooNe first results press release and
- MiniBooNE website
- Overview of MiniBooNE for Mineral Oil Suppliers
- An informal discussion of the experiment and initial results
- Experiment Nixes Fourth Neutrino (April 2007 Scientific American)
- Dimensional Shortcuts - evidence for sterile neutrino; (August 2007; Scientific American)