- 1700 - Neutrino - A summary of what we have learned so far. They are nearly massless and travel nearly the speed of light. They are as abundant as photons but behave quite differently. They are generated in fusion and fission processes, some to enormous energies.
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--------------------------- 1700 - Neutrino - What we learned about the “Little One“?
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- Neutrinos, what are they and where did they come from? Neutrinos are atomic particles, part of the nucleus of atoms. Their charges are neutral and they are nearly massless. The photon is massless, simply a particle of energy. The neutrino is close to massless. Neutrinos do not interact with matter except slightly with the Weak Nuclear Force. Also, if they have a slight mass then that implies they must also interact with the Higgs Field.
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- Neutrinos bombard us constantly because they arrive with the Sunlight. The fusion reactions at the core of the Sun produces billions of neutrinos. They arrive at near the speed of light and pass right through our bodies and through the entire Earth without obstruction.
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- Hold up your thumb towards the Sun.
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- 65,000,000,000 neutrinos are passing through your thumbnail every second. Neutrinos pass through your body unimpeded. That is why they are so hard to detect.
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- In contrast photons are massless and carry energy depending on their wavelength. In sunlight 79,000,000,000,000,000 photons hit your thumbnail every second. Your eye can detect their reflection, maybe even feel some heat from ultraviolet. You would even see the bone if it were X-rays wavelengths. The shorter the wavelength the greater the energy. E = h / w.
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- Neutrino mass is small, unknown , but less than 1,000,000th the mass of an electron.
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------------------ Neutrino mass < 0.13 electron volts / c^2
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- Neutrino’s energy comes in three generations:
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--------------------Electron Neutrinos < 2.5 electron volts
--------------------Muon Neutrinos < 170,000 electron volts
--------------------Tau Neutrinos < 18,000,000 electron volts
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- How can we possible catch one of these “little ones” to study it?
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- Astronomers have made a major attempt at the South Pole. They have installed 5,160 detectors in one cubic kilometer of ice. After 2 years of data collecting astronomers think they have discovered 80 high energy Tau Neutrinos that came to us from somewhere , other than our Sun, which are all low energy Electron Neutrinos. One possibility is that Cosmic Rays slamming into our upper atmosphere could produce high energy neutrinos, much like a particle accelerator does in our science labs.
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- These high energy Tau Neutrinos carry 10 trillion times more energy than visible light photons. They have 1 million times more energy than the neutrinos discovered coming from the Supernova 1987A that occurred in our neighbor galaxy, the Large Megellanic Cloud.
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- Neutrinos are generated in fusion and fission reactions in stars mostly. However, low energy neutrinos are created in radioactive decay. Your body contains 20 milligrams of Potassium 40, a natural radioactive element. As a result your body is emitting 340,000,000 neutrinos every day. But, don’t expect to loose much weight.
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- Low energy neutrinos exit the fusion in the core of the Sun and reach the Earth in 8 minutes, nearly the speed of light. Photons created at the same time in Gamma Ray wavelengths interact with the electromagnetic and nuclear forces in the hydrogen and helium atoms scattering so many times it takes them 40,000 years to reach the surface of the Sun. By then they have lost so much energy their longer wavelengths are green light that reaches the Earth in 8 minutes scatters in the upper nitrogen atmosphere creating a blue sky and a yellow Sun to us surface dwellers.
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- For astronomers it has been a mystery where the high energy, Tau Neutrinos, are being created. They come from somewhere outside our Solar System. Astronomers have 4 instruments using coordinated detection to possibly answer this question:
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------------------------ ICECube Neutrino Observatory at the South Pole
------------------------ Chandra X-ray observatory in orbit.
------------------------ Swift Gamma-Ray observatory in orbit
------------------------ Nuclear Spectroscopic Telescope, NuSTAR
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- Over the last 4 years, 2010 - 2014, ICECube has detected 80 high energy Tau Neutrinos. ( See Review # 1219 to learn about the ICECube observatory).
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- Chandra X-ray observatory witnessed a giant flare outburst from the Blackhole at the center of our Milky Way Galaxy. Exactly 3 hours later ICECube detected a neutrino signature. 3 other X-ray telescopes detectors received corresponding data on this high energy neutrino.
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------------ CONCLUSION: Blackholes are one source for high energy neutrinos.
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- Astronomer’s theory is that particles orbiting around a Blackhole get accelerated by a shockwave, like a sonic boom, launching charged particles at enormous velocities that decay into high energy neutrinos. This may be the same mechanism that launches high energy Cosmic Rays. But, Cosmic Rays are charged particles that change directions in magnetic fields so many times we can not determine their trajectories.
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- Could all these neutrinos in the Cosmos explain Dark Matter that represents 23% of all the mass-energy in the Universe. Normal matter represents less than 5%.
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- If we really did invent a neutrino telescope we could learn a lot about the Universe. Electromagnetic wave detection is nice but still limiting in how much we can see. Stay tuned, there is much more to learn.
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- Other Reviews on the topic of Neutrinos available upon request:
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- #1631 Neutrinos used to detect Supernovae Explosions.
- #1608 Left-handed neutrinos interact with Gravity ad the Weak Nuclear Force.
- #1589 Neutrinos have a half-spin in angular momentum.
- #1511 Sterile Neutrinos, would interact with Gravity but none of the other forces.
- # 1219 ICE Cube , neutrino telescope at the South Pole.
- # 1139 The Universe will light up when we can see with neutrino eyes.
- # 732 Neutrino Thermal history, Big Bang to present.
- # 630 History of neutrino discoveries since 1927.
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RSVP, with comments, suggestions, corrections. Index of reviews available ---
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