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A neutrino is a fermion that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small (-ino) that it was long thought to be zero. The rest mass of the neutrino is much smaller than that of the other known elementary particles excluding massless particles. The weak force has a very short range, the gravitational interaction is extremely weak due to the very small mass of the neutrino, and neutrinos do not participate in the strong interaction. Thus, neutrinos typically pass through normal matter unimpeded and undetected.
The Sudbury Neutrino Observatory (SNO) was a neutrino observatory located 2100 m underground in Vale's Creighton Mine in Sudbury, Ontario, Canada. The detector was designed to detect solar neutrinos through their interactions with a large tank of heavy water.
Frederick Reines was an American physicist. He was awarded the 1995 Nobel Prize in Physics for his co-detection of the neutrino with Clyde Cowan in the neutrino experiment. He may be the only scientist in history "so intimately associated with the discovery of an elementary particle and the subsequent thorough investigation of its fundamental properties."
Neutrino astronomy is the branch of astronomy that observes astronomical objects with neutrino detectors in special observatories. Neutrinos are created as a result of certain types of radioactive decay, nuclear reactions such as those that take place in the Sun or high energy astrophysical phenomena, in nuclear reactors, or when cosmic rays hit atoms in the atmosphere. Neutrinos rarely interact with matter, meaning that it is unlikely for them to scatter along their trajectory, unlike photons. Therefore, neutrinos offer a unique opportunity to observe processes that are inaccessible to optical telescopes, such as reactions in the Sun's core. Neutrinos can also offer a very strong pointing direction compared to charged particle cosmic rays.
The Cowan–Reines neutrino experiment was conducted by physicists Clyde Cowan and Frederick Reines in 1956. The experiment confirmed the existence of neutrinos. Neutrinos, subatomic particles with no electric charge and very small mass, had been conjectured to be an essential particle in beta decay processes in the 1930s. With neither mass nor charge, such particles appeared to be impossible to detect. The experiment exploited a huge flux of electron antineutrinos emanating from a nearby nuclear reactor and a detector consisting of large tanks of water. Neutrino interactions with the protons of the water were observed, verifying the existence and basic properties of this particle for the first time.
A solar neutrino is a neutrino originating from nuclear fusion in the Sun's core, and is the most common type of neutrino passing through any source observed on Earth at any particular moment. Neutrinos are elementary particles with extremely small rest mass and a neutral electric charge. They only interact with matter via the weak interaction and gravity, making their detection very difficult. This has led to the now-resolved solar neutrino problem. Much is now known about solar neutrinos, but the research in this field is ongoing.
A neutrino detector is a physics apparatus which is designed to study neutrinos. Because neutrinos only weakly interact with other particles of matter, neutrino detectors must be very large to detect a significant number of neutrinos. Neutrino detectors are often built underground, to isolate the detector from cosmic rays and other background radiation. The field of neutrino astronomy is still very much in its infancy – the only confirmed extraterrestrial sources as of 2018 are the Sun and the supernova 1987A in the nearby Large Magellanic Cloud. Another likely source is the blazar TXS 0506+056 about 3.7 billion light years away. Neutrino observatories will "give astronomers fresh eyes with which to study the universe".
The Homestake experiment was an experiment headed by astrophysicists Raymond Davis, Jr. and John N. Bahcall in the late 1960s. Its purpose was to collect and count neutrinos emitted by nuclear fusion taking place in the Sun. Bahcall performed the theoretical calculations and Davis designed the experiment. After Bahcall calculated the rate at which the detector should capture neutrinos, Davis's experiment turned up only one third of this figure. The experiment was the first to successfully detect and count solar neutrinos, and the discrepancy in results created the solar neutrino problem. The experiment operated continuously from 1970 until 1994. The University of Pennsylvania took it over in 1984. The discrepancy between the predicted and measured rates of neutrino detection was later found to be due to neutrino "flavour" oscillations.
The Kamioka Observatory, Institute for Cosmic Ray Research is a neutrino and gravitational waves laboratory located underground in the Mozumi mine of the Kamioka Mining and Smelting Co. near the Kamioka section of the city of Hida in Gifu Prefecture, Japan. A set of groundbreaking neutrino experiments have taken place at the observatory over the past two decades. All of the experiments have been very large and have contributed substantially to the advancement of particle physics, in particular to the study of neutrino astronomy and neutrino oscillation.
SNO+ is a physics experiment designed to search for neutrinoless double beta decay, with secondary measurements of proton–electron–proton (pep) solar neutrinos, geoneutrinos from radioactive decays in the Earth, and reactor neutrinos. It is under construction using the underground equipment already installed for the former Sudbury Neutrino Observatory (SNO) experiment at SNOLAB. It could also observe supernovae neutrinos if a supernova occurs in our galaxy.
The Kolar Gold Fields (KGF), located in the Kolar district of the state of Karnataka, India, are a set of defunct gold mines known for the neutrino particle experiments and observations that took place there starting in 1960. The experiments ended with the closing of the mine in 1992.
Yoji Totsuka was a Japanese physicist and Special University Professor, Emeritus, University of Tokyo. A leader in the study of solar and atmospheric neutrinos, he was a scientist and director at Kamioka Observatory, Super-Kamiokande and the High Energy Physics Laboratory (KEK) in Japan.
The solar neutrino problem concerned a large discrepancy between the flux of solar neutrinos as predicted from the Sun's luminosity and as measured directly. The discrepancy was first observed in the mid-1960s and was resolved around 2002.
Large Apparatus studying Grand Unification and Neutrino Astrophysics or LAGUNA is or was a European project aimed to develop the next-generation, very large volume underground neutrino observatory. The detector should be much bigger and more sensitive than any previous detector, and make new discoveries in the field of particle and astroparticle physics. The project involves 21 European institutions in 10 European countries, and brings together over 100 scientists. As of 2011, the project was assessing the feasibility of developing the observatory-infrastructure and the observatory particle detectors themselves, as well as looking for a deployment site in Europe. There have also been propositions of merging the project with similar international projects, like DUSEL.
The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) is a proposed water Cherenkov detector experiment designed to examine the nature of neutrino interactions. This experiment will study phenomena like proton decay, and neutrino oscillations, by analyzing neutrino interactions in gadolinium-loaded water and measuring their neutron yield. Neutron Tagging plays an important role in background rejection from atmospheric neutrinos. By implementing early prototypes of LAPPDs, high precision timing is possible. The suggested location for ANNIE is the SciBooNE hall on the Booster Neutrino Beam associated with the MiniBooNE experiment. The neutrino beam originates in Fermilab where The Booster delivers 8 GeV protons to a beryllium target producing secondary pions and kaons. These secondary mesons decay to produce a neutrino beam with an average energy of around 800 MeV. ANNIE will begin installation in the summer of 2015. Phase I of ANNIE, mapping the neutron background, completed in 2017. The detector is being upgraded for full science operation which is expected to begin late 2018.
Herbert Hwa-sen Chen was a theoretical and experimental physicist at the University of California at Irvine known for his contributions in the field of neutrino detection. Chen's work on observations of elastic neutrino-electron scattering provided important experimental support for the electroweak theory of the standard model of particle physics. In 1984 Chen realized that the deuterium of heavy water could be used as a detector that would distinguish the flavors of solar neutrinos. This idea led Chen to develop plans for the Sudbury Neutrino Observatory that would eventually make fundamental measurements demonstrating that neutrinos were particles with mass.
Eugene William Beier is an American physicist.
FASER is one of the nine particle physics experiments in 2022 at the Large Hadron Collider at CERN. It is designed to both search for new light and weakly coupled elementary particles, and to detect and study the interactions of high-energy collider neutrinos. In 2023, FASER and SND@LHC reported the first observation of collider neutrinos.
Supernova neutrinos are weakly interactive elementary particles produced during a core-collapse supernova explosion. A massive star collapses at the end of its life, emitting on the order of 1058 neutrinos and antineutrinos in all lepton flavors. The luminosity of different neutrino and antineutrino species are roughly the same. They carry away about 99% of the gravitational energy of the dying star as a burst lasting tens of seconds. The typical supernova neutrino energies are 10 to 20 MeV. Supernovae are considered the strongest and most frequent source of cosmic neutrinos in the MeV energy range.
References
- ↑ The Underground Search for Clues to an Unstable Universe, Popular Science, Vol. 219, No. 8 (December, 1981); pages 64-67.
- ↑ John C. Vander Velde's IMB page, accessed 11 April 2008.
- ↑ A Proposal for a Long Baseline Oscillation Experiment Using A High Intensity Neutrino Beam from the Fermilab Main Injector to the IMB Water Cerenkov Detector; FNAL P805.
- ↑ "IMB Detector: The First 30-Days." D. Sinclair et al. 1982. Los Alamos 1982, Proceedings, Science Underground, pg. 138-142.
- ↑ Russell J. Clark's IMB page Archived 2004-12-14 at the Wayback Machine , accessed 5 July 2006.