Bruno Pontecorvo

In response to this solar neutrino problem, he proposed a phenomenon known as neutrino oscillation, whereby electron neutrinos became muon neutrinos. The existence of the oscillations was finally established by the Super-Kamiokande experiment in 1998. He also predicted in 1958 that supernovae would produce intense bursts of neutrinos, which was confirmed in 1987 when Supernova SN1987A was detected by neutrino detectors. Pontecorvo was born on 22 August in Marina di Pisa, the fourth of eight children of Massimo Pontecorvo and his wife Maria. His older brother Guido, who was born in 1907, became a geneticist.


solarSolThe Sun
This discrepancy was resolved in 2001 through the discovery of the effects of neutrino oscillation: the Sun emits the number of neutrinos predicted by the theory, but neutrino detectors were missing 2⁄3 of them because the neutrinos had changed flavor by the time they were detected. The Sun has a magnetic field that varies across the surface of the Sun. Its polar field is 1 - 2 G, whereas the field is typically 3000 G in features on the Sun called sunspots and 10 - 100 G in solar prominences. The magnetic field also varies in time and location. The quasi-periodic 11-year solar cycle is the most prominent variation in which the number and size of sunspots waxes and wanes.

Sudbury Neutrino Observatory

SNOSNO (Sudbury Neutrino Observatory)Sudbury
As several experiments confirmed this deficit the effect became known as the solar neutrino problem. Over several decades many ideas were put forward to try to explain the effect, one of which was the hypothesis of neutrino oscillations. All of the solar neutrino detectors prior to SNO had been sensitive primarily or exclusively to electron neutrinos and yielded little to no information on muon neutrinos and tau neutrinos. In 1984, Herb Chen of the University of California at Irvine first pointed out the advantages of using heavy water as a detector for solar neutrinos.

Homestake experiment

chlorine experimentHomestakeHomestake neutrino experiment
SNO was the first detector able to detect neutrino oscillation, solving the solar neutrino problem. The results of the experiment, published in 2001, revealed that of the three "flavours" between which neutrinos are able to oscillate, Davis's detector was sensitive to only one. After it had been proven that his experiment was sound, Davis shared the 2002 Nobel Prize in Physics. Among those sharing the prize was Masatoshi Koshiba of Japan, who worked on the Kamiokande and the Super Kamiokande. *Cowan–Reines neutrino experiment (a previous experiment by Reines and Cowan which discovered the antineutrino) * Raymond Davis Jr.'s Solar Neutrino Experiments (at


neutrinosantineutrinoneutrino mass
This resolved the solar neutrino problem: the electron neutrinos produced in the Sun had partly changed into other flavors which the experiments could not detect. Although individual experiments, such as the set of solar neutrino experiments, are consistent with non-oscillatory mechanisms of neutrino flavor conversion, taken altogether, neutrino experiments imply the existence of neutrino oscillations. Especially relevant in this context are the reactor experiment KamLAND and the accelerator experiments such as MINOS. The KamLAND experiment has indeed identified oscillations as the neutrino flavor conversion mechanism involved in the solar electron neutrinos.

Takaaki Kajita

Dr Takaaki KajitaT. Kajita
This discovery helped prove the existence of neutrino oscillation and that neutrinos have mass. In 2015, Kajita shared the Nobel Prize in Physics with Canadian physicist Arthur McDonald, whose Sudbury Neutrino Observatory discovered similar results. Kajita's and McDonald's work solved the longstanding Solar neutrino problem, which was a major discrepancy between the predicted and measured Solar neutrino fluxes, and indicated that the Standard Model, which required neutrinos to be massless, had weaknesses. In a news conference at the University of Tokyo, shortly after the Nobel announcement, Kajita said, "I want to thank the neutrinos, of course.


Super KamiokandeSuper-KSuper-Kamiokande Observatory
Solar neutrino problem. Sudbury Neutrino Observatory. K2K experiment. T2K experiment.

Kamioka Observatory

KamiokandeKamiokande IIKamioka mine
The KEK To Kamioka experiment used accelerator neutrinos to verify the oscillations observed in the atmospheric neutrino signal with a well controlled and understood beam. A neutrino beam was directed from the KEK accelerator to Super Kamiokande. The experiment found oscillation parameters which were consistent with those measured by Super-K. By the 1990s particle physicists were starting to suspect that the solar neutrino problem and atmospheric neutrino deficit had something to do with neutrino oscillation. The Super Kamiokande detector was designed to test the oscillation hypothesis for both solar and atmospheric neutrinos.

Solar neutrino

solar neutrinossolarneutrino emissions from the Sun
Note that Borexino measured neutrinos of several energies; in this manner they have demonstrated experimentally, for the first time, the pattern of solar neutrino oscillations predicted by the theory. Neutrinos can trigger nuclear reactions. By looking at ancient ores of various ages that have been exposed to solar neutrinos over geologic time, it may be possible to interrogate the luminosity of the Sun over time, which, according to the Standard Solar Model, has changed with time. * Neutrino oscillations. Solar neutrino problem. Neutrino detector. Neutral particle oscillation. Solar neutrino unit.

Arthur B. McDonald

Art McDonaldArthur McDonaldA. McDonald
McDonald and Oscillating Neutrinos. Arthur B. McDonald Quotes With Pictures.

Mikheyev–Smirnov–Wolfenstein effect

MSW effectanalytic understanding of MSW effectmatter effects
These results are further supported by the reactor experiment KamLAND, that is uniquely able to measure the parameters of oscillation that are also consistent with all other measurements. The transition between the low energy regime (the MSW effect is negligible) and the high energy regime (the oscillation probability is determined by matter effects) lies in the region of about 2 MeV for the Solar neutrinos. The MSW effect can also modify neutrino oscillations in the Earth, and future search for new oscillations and/or leptonic CP violation may make use of this property. *Neutrino oscillations Citations Bibliography *

Standard Model

standard model of particle physicsThe Standard ModelStandard Model of Physics
It also does not incorporate neutrino oscillations and their non-zero masses. The development of the Standard Model was driven by theoretical and experimental particle physicists alike. For theorists, the Standard Model is a paradigm of a quantum field theory, which exhibits a wide range of phenomena including spontaneous symmetry breaking, anomalies and non-perturbative behavior. It is used as a basis for building more exotic models that incorporate hypothetical particles, extra dimensions, and elaborate symmetries (such as supersymmetry) in an attempt to explain experimental results at variance with the Standard Model, such as the existence of dark matter and neutrino oscillations.

Particle physics

high energy physicsparticle physicisthigh-energy physics
It is the home of a number of experiments such as the K2K experiment, a neutrino oscillation experiment and Belle II, an experiment measuring the CP violation of B mesons. SLAC National Accelerator Laboratory (Menlo Park, United States). Its 2-mile-long linear particle accelerator began operating in 1962 and was the basis for numerous electron and positron collision experiments until 2008. Since then the linear accelerator is being used for the Linac Coherent Light Source X-ray laser as well as advanced accelerator design research. SLAC staff continue to participate in developing and building many particle detectors around the world. Introductory reading. Advanced reading.

Liquid Scintillator Neutrino Detector

LSNDliquid scintillatorLSN Detector
The experiment collected data from 1993 to 1998. * LSND strengthens evidence for neutrino oscillations. LSND scientific publications. LSND scientific publications, SPIRES database. The Neutrino Oscillations Industry.

Raymond Davis Jr.

Raymond Davis, Jr.Ray DavisRaymond Davis
"Solar Neutrino Problem", Brookhaven National Laboratory (BNL), (April 28, 1978). Davis, R. Jr., Cleveland, B. T. & J. K. Rowley. "Variations in the Solar Neutrino Flux", Department of Astronomy and Astrophysics at University of Pennsylvania, Los Alamos National Laboratory (LANL), Brookhaven National Laboratory (BNL), (August 2, 1987). Raymond Davis Jr. biography at the Nobel Foundation. Raymond Davis Jr., Brookhaven National Lab Web site. Neutrino web at PBS NOVA. The Raymond Davis Scholarship Society for Imaging Science and Technology.

Standard solar model

and elements such as lithium which are underrepresented in the Sun's photosphereLithium depletion problem
The solution to the solar neutrino problem was finally experimentally determined by the Sudbury Neutrino Observatory (SNO). The radiochemical experiments were only sensitive to electron neutrinos, and the signal in the water Cerenkov experiments was dominated by the electron neutrino signal. The SNO experiment, by contrast, had sensitivity to all three neutrino flavours.

Neutrino detector

neutrino telescopeneutrino detectionneutrino observatory
A chlorine detector in the former Homestake Mine near Lead, South Dakota, containing 520 short tons (470 metric tons) of fluid, was the first to detect the solar neutrinos, and made the first measurement of the deficit of electron neutrinos from the sun (see Solar neutrino problem). A similar detector design, with a much lower detection threshold of 0.233 MeV, uses a gallium → germanium transformation which is sensitive to lower-energy neutrinos. A neutrino is able to react with an atom of gallium-71, converting it into an atom of the unstable isotope germanium-71. The germanium was then chemically extracted and concentrated.


solar oscillationHelioseismicHelioseismography
The so-called solar neutrino problem was ultimately resolved by neutrino oscillations. The experimental discovery of neutrino oscillations was recognized by the 2015 Nobel Prize for Physics. Helioseismology also allowed accurate measurements of the quadrupole (and higher-order) moments of the Sun's gravitational potential, which are consistent with general relativity. The first helioseismic calculations of the Sun's internal rotation profile showed a rough separation into a rigidly-rotating core and differentially-rotating envelope. The boundary layer is now known as the tachocline and is thought to be a key component for the solar dynamo.

Kamioka Liquid Scintillator Antineutrino Detector

If neutrinos have mass, they may oscillate into flavors that an experiment may not detect, leading to a further dimming, or "disappearance," of the electron antineutrinos. KamLAND is located at an average flux-weighted distance of approximately 180 kilometers from the reactors, which makes it sensitive to the mixing of neutrinos associated with large mixing angle (LMA) solutions to the solar neutrino problem. The KamLAND detector's outer layer consists of an 18 meter-diameter stainless steel containment vessel with an inner lining of 1,879 photo-multiplier tubes (1325 17" and 554 20" PMTs). Photocathode coverage is 34%.

Herbert H. Chen

Herb Chen
The observations by SNO would demonstrate that neutrinos oscillated between neutrino flavors (electron, muon, and tau), thus demonstrating that the neutrino was not massless. For this fundamental discovery in physics, McDonald and the Sudbury Neutrino Observatory Collaboration were awarded the 2015 Nobel Prize in Physics jointly with Japanese physicist Takaaki Kajita and the Super-Kamiokande Collaboration. * HUGH EN CHEN (1901-1993) An informal letter describing Herb Chen's family and immigration to the United States in 1955 (China National Aviation Corporation website) (Access date 24-01-2017) Solar neutrino problem. Frederick Reines. Neutrino oscillation. SN 1987A. Neutrino astronomy.


Earth's surfaceterrestrialworld
Shifts in the oceanic temperature distribution can cause significant weather shifts, such as the El Niño–Southern Oscillation. The atmospheric pressure at Earth's sea level averages 101.325 kPa, with a scale height of about 8.5 km. A dry atmosphere is composed of 78.084% nitrogen, 20.946% oxygen, 0.934% argon, and trace amounts of carbon dioxide and other gaseous molecules. Water vapor content varies between 0.01% and 4% but averages about 1%. The height of the troposphere varies with latitude, ranging between 8 km at the poles to 17 km at the equator, with some variation resulting from weather and seasonal factors. Earth's biosphere has significantly altered its atmosphere.

Quantum state

eigenstatepure stateeigenstates
Quantum harmonic oscillator. Quantum logic gate. Qubit. State vector reduction, for historical reasons called a wave function collapse. Stationary state. W state.

Cherenkov radiation

CherenkovCherenkov effectCherenkov light
Cherenkov radiation (IPA: /tʃɛrɛnˈkɔv/, Russian: Черенков) is electromagnetic radiation emitted when a charged particle (such as an electron) passes through a dielectric medium at a speed greater than the phase velocity of light in that medium. The characteristic blue glow of an underwater nuclear reactor is due to Cherenkov radiation. It is named for Soviet physicist Pavel Cherenkov, who shared the 1958 Nobel Prize in Physics for its discovery.

Nobel Prize in Physics

Nobel PrizePhysicsNobel Prize for Physics
The Nobel Prize in Physics is a yearly award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions for mankind in the field of physics. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others being the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and Nobel Prize in Physiology or Medicine.

Complex number

complexreal partimaginary part
Since the voltage in an AC circuit is oscillating, it can be represented as To obtain the measurable quantity, the real part is taken: The complex-valued signal V(t) is called the analytic representation of the real-valued, measurable signal v(t). In fluid dynamics, complex functions are used to describe potential flow in two dimensions. The complex number field is intrinsic to the mathematical formulations of quantum mechanics, where complex Hilbert spaces provide the context for one such formulation that is convenient and perhaps most standard. The original foundation formulas of quantum mechanics – the Schrödinger equation and Heisenberg's matrix mechanics – make use of complex numbers.