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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. 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 electromagnetic interaction or 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.
The Greisen–Zatsepin–Kuzmin limit (GZK limit or GZK cutoff) is a theoretical upper limit on the energy of cosmic ray protons traveling from other galaxies through the intergalactic medium to our galaxy. The limit is 5×1019 eV (50 EeV), or about 8 joules (the energy of a proton travelling at ≈ 99.99999999999999999998% the speed of light). The limit is set by the slowing effect of interactions of the protons with the microwave background radiation over long distances (≈ 160 million light-years). The limit is at the same order of magnitude as the upper limit for energy at which cosmic rays have experimentally been detected, although indeed some detections appear to have exceeded the limit, as noted below. For example, one extreme-energy cosmic ray, the Oh-My-God Particle, which has been found to possess a record-breaking 3.12×1020 eV (50 joules) of energy (about the same as the kinetic energy of a 95 km/h baseball).
Masatoshi Koshiba was a Japanese physicist and one of the founders of neutrino astronomy. His work with the neutrino detectors Kamiokande and Super-Kamiokande was instrumental in detecting solar neutrinos, providing experimental evidence for the solar neutrino problem.
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.
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.
The IceCube Neutrino Observatory is a neutrino observatory constructed at the Amundsen–Scott South Pole Station in Antarctica. The project is a recognized CERN experiment (RE10). Its thousands of sensors are located under the Antarctic ice, distributed over a cubic kilometre.
Main injector neutrino oscillation search (MINOS) was a particle physics experiment designed to study the phenomena of neutrino oscillations, first discovered by a Super-Kamiokande (Super-K) experiment in 1998. Neutrinos produced by the NuMI beamline at Fermilab near Chicago are observed at two detectors, one very close to where the beam is produced, and another much larger detector 735 km away in northern Minnesota.
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 Kamioka Gravitational Wave Detector (KAGRA), is a large interferometer designed to detect gravitational waves predicted by the general theory of relativity. KAGRA is a Michelson interferometer that is isolated from external disturbances: its mirrors and instrumentation are suspended and its laser beam operates in a vacuum. The instrument's two arms are three kilometres long and located underground at the Kamioka Observatory which is near the Kamioka section of the city of Hida in Gifu Prefecture, Japan.
T2K is a particle physics experiment studying the oscillations of the accelerator neutrinos. The experiment is conducted in Japan by the international cooperation of about 500 physicists and engineers with over 60 research institutions from several countries from Europe, Asia and North America and it is a recognized CERN experiment (RE13). T2K collected data within its first phase of operation from 2010 till 2021. The second phase of data taking (T2K-II) is expected to start in 2023 and last until commencement of the successor of T2K – the Hyper-Kamiokande experiment in 2027.
Hyper-Kamiokande is a neutrino observatory and experiment under construction, conducted in Japan by the collaboration of institutes from 21 countries from six continents. As a successor of the Super-Kamiokande (SK) and T2K experiments, it is designed to search for proton decay and detect neutrinos from natural sources such as the Earth, the atmosphere, the Sun and the cosmos, as well as to study neutrino oscillations of the man-made accelerator neutrino beam. The beginning of data-taking is planned for 2027.
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.
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 Baikal Deep Underwater Neutrino Telescope (BDUNT) is a neutrino detector conducting research below the surface of Lake Baikal (Russia) since 2003. The first detector was started in 1990 and completed in 1998. It was upgraded in 2005 and again starting in 2015 to build the Baikal Gigaton Volume Detector (Baikal-GVD.) BDUNT has studied neutrinos coming through the Earth with results on atmospheric muon flux. BDUNT picks up many atmospheric neutrinos created by cosmic rays interacting with the atmosphere – as opposed to cosmic neutrinos which give clues to cosmic events and are therefore of greater interest to physicists.
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.
The K2K experiment was a neutrino experiment that ran from June 1999 to November 2004. It used muon neutrinos from a well-controlled and well-understood beam to verify the oscillations previously observed by Super-Kamiokande using atmospheric neutrinos. This was the first positive measurement of neutrino oscillations in which both the source and detector were fully under experimenters' control. Previous experiments relied on neutrinos from the Sun or from cosmic sources. The experiment found oscillation parameters which were consistent with those measured by Super-Kamiokande.
Multi-messenger astronomy is astronomy based on the coordinated observation and interpretation of signals carried by disparate "messengers": electromagnetic radiation, gravitational waves, neutrinos, and cosmic rays. They are created by different astrophysical processes, and thus reveal different information about their sources.
Eugene William Beier is an American physicist.
The diffuse supernova neutrino background(DSNB) is a theoretical population of neutrinos (and anti-neutrinos) cumulatively originating from all core-collapse supernovae events throughout the history of the universe. Though it has not yet been directly detected, the DSNB is theorized to be isotropic and consists of neutrinos with typical energies on the scale of 107 eV. Current detection efforts are limited by the influence of background noise in the search for DSNB neutrinos and are therefore limited to placing limits on the parameters of the DSNB, namely the neutrino flux. Restrictions on these parameters have gotten more strict in recent years, but many researchers are looking to make direct observations in the near future with next generation detectors. The DSNB is not to be confused with the cosmic neutrino background (CNB), which is comprised by relic neutrinos that were produced during the Big Bang and have much lower energies (10−4 to 10−6 eV).
References
- ↑ "P-ONE: Why we need another neutrino telescope". The P-ONE Collaboration . 1 January 2022. Retrieved 19 January 2022.
- 1 2 Sutter, Paul (18 January 2022). "Astronomers propose building a neutrino telescope — out of the Pacific Ocean - Meet the ambitious P-ONE proposal". Space.com . Retrieved 19 January 2022.
- 1 2 3 Resconi, Elisa; et al. (P-ONE Collaboration) (25 November 2021). The Pacific Ocean Neutrino Experiment. 37th International Cosmic Ray Conference. 12-23 July 2021. Berlin. p. 24. arXiv: 2111.13133 . Bibcode:2022icrc.confE..24R. doi: 10.22323/1.395.0024 .
- ↑ Agnostini, Matteo; et al. (8 September 2020). "The Pacific Ocean Neutrino Experiment". Nature . 4 (10): 913–915. arXiv: 2005.09493 . Bibcode:2020NatAs...4..913A. doi:10.1038/s41550-020-1182-4. S2CID 218684893 . Retrieved 19 January 2022.