While theories for gamma-ray sources are often not conclusive regarding the presence of cosmic rays in the sources, cosmic rays interacting in the sources with matter or photons will lead to neutrino production. This means that cosmic rays and neutrinos are intimately connected..
How is a neutrino created?
Every time atomic nuclei come together (like in the sun) or break apart (like in a nuclear reactor), they produce neutrinos. Even a banana emits neutrinos—they come from the natural radioactivity of the potassium in the fruit. Once produced, these ghostly particles almost never interact with other matter..
What is meant by cosmic neutrinos?
Neutrinos react rarely with normal matter, making them great messengers for phenomena happening far beyond our own galaxy. Undeterred by intervening planets, stars, and light-years of space, these neutrinos carry information from distant sources to our doorstep. It's the dawn of neutrino astrophysics.
What is meant by cosmic neutrinos?
The cosmic neutrino background (CNB or CνB) is the universe's background particle radiation composed of neutrinos. They are sometimes known as relic neutrinos..
In 1997 Super-Kamiokande reported a deficit of cosmic-ray muon neutrinos and solar electron neutrinos at rates that agreed with measurements by earlier experiments. And in 1998, after analyzing 535 days of data, the Super-Kamiokande team reported finding oscillations—and so mass—in muon neutrinos.
The role that neutrinos may play in formation of large scale structure of the universe is described and neutrino mass limits are presented. Effects of neutrinos on cos- mological background radiation and on big bang nucleosynthesis are discussed. Limits on the number of neutrino flavors and mass/mixing are given.
While theories for gamma-ray sources are often not conclusive regarding the presence of cosmic rays in the sources, cosmic rays interacting in the sources with matter or photons will lead to neutrino production. This means that cosmic rays and neutrinos are intimately connected.
Cosmic neutrinos are generated by cosmic rays in extragalactic sources that can be thought of as “cosmic accelerators.” These neutrinos carry far more energy than any other kind of neutrino we see here on Earth—and more than we could hope to produce in any of our experiments.
The cosmic neutrino background is the universe's background particle radiation composed of neutrinos. They are sometimes known as relic neutrinos. Wikipedia
The Liquid Scintillator Neutrino Detector (LSND) was a scintillation counter at Los Alamos National Laboratory that measured the number of neutrinos being produced by an accelerator neutrino source. The LSND project was created to look for evidence of neutrino oscillation, and its results conflict with the Standard Model expectation of only three neutrino flavors, when considered in the context of other solar and atmospheric neutrino oscillation experiments. Cosmological data bound the mass of the sterile neutrino to ms < 0.26eV (0.44eV) at 95% (99.9%) confidence limit, excluding at high significance the sterile neutrino hypothesis as an explanation of the LSND anomaly. The controversial LSND result was tested by the MiniBooNE experiment at Fermilab which has found similar evidence for oscillations. The hint is currently undergoing further tests at MicroBooNE at Fermilab.
In Big Bang cosmology, neutrino decoupling was the epoch at which neutrinos ceased interacting with other types of matter, and thereby ceased influencing the dynamics of the universe at early times. Prior to decoupling, neutrinos were in thermal equilibrium with protons, neutrons and electrons, which was maintained through the weak interaction. Decoupling occurred approximately at the time when the rate of those weak interactions was slower than the rate of expansion of the universe. Alternatively, it was the time when the time scale for weak interactions became greater than the age of the universe at that time. Neutrino decoupling took place approximately one second after the Big Bang, when the temperature of the universe was approximately 10 billion kelvin, or 1 MeV.
Cosmological neutrinos
Phenomenon in which a neutrino changes lepton flavor as it travels
Neutrino oscillation is a quantum mechanical phenomenon in which a neutrino created with a specific lepton family number can later be measured to have a different lepton family number. The probability of measuring a particular flavor for a neutrino varies between three known states, as it propagates through space.
