- 3006 - NEUTRINOS - what have we learned? Neutrinos are the smallest atomic particles. If we could see neutrinos they would be exceptional probes into our environment. Neutrinos are produced in fusions reactions in the Sun and stars, and in radioactive decay in the earth's crust. The “ICECUBE neutrino detector” at the South Pole has over 5,000 light sensors to detect neutrinos interacting with atoms in the ice.
------------------- 3006 - NEUTRINOS - what have we learned?
- Neutrinos are the smallest atomic particles. If we could see neutrinos they would be exceptional probes into our environment. Neutrino means " the little one", they were first detected in 1956.
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- There are 3 varieties of neutrinos that behave the same, but all have different atomic weights. They all are electrically neutral so they pass through matter undetected. More than 50,000,000,000,000 neutrinos pass through your body every second. ( Review 2835 for more.)
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- Neutrinos are produced in fusions reactions in the Sun and stars, and in radioactive decay in the earth's crust. Potassium 40 in our body is one of these natural radioactive decay elements. Your body emits 340,000,000 neutrinos each day. The Sun emits 2*10^36 and the Earth receives 65 billion neutrinos per second per square centimeter. (Review 630: Six sources of Neutrinos. The history of the discoveries of neutrinos from 1927 to 2006)
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- Where have all the neutrinos gone? Neutrinos have been thought to exist since 1930. When radioactive decay added up the before energy and the after energy a small amount was missing. Wolfgang Pauli called this missing energy the neutrino. (Review 1139)
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- ICECUBE is a neutrino telescope built deep in the ice at the South Pole. ( Review 1219 describes how the telescope was built, how it works and what it expects to discover.)
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- There may be an undiscovered particle called the "sterile neutrino". This neutrino would interact with gravity but not with any of the other forces. This may explain Dark Matter that makes up 23% of the Universe. (Reviesw 1511)
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- In order for the neutrino to be nearly massless it must have a very weak interaction with the Higgs Field. Every particle has a counterpart anti-particle . The neutrino may be different and be its own anti-particle. (Review 1589)
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- In 2013 neutrinos can be routinely detected. Neutrinos are "leptons´ because they have 1/2 spin in their angular momentum. Neutrinos leave the Sun and reach us in 8 minutes. While reading this sentence 5,000,000 of them passed through your thumbnail. (Review 1608)
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- Neutrinos are neutral particles that travel in a straight line. They arrive hours ahead of light coming from supernovae explosions. The mass of these neutrinos must be very, very small because they are traveling nearly the speed of light. Neutrino measurements show some that are accelerated to energies above 50 trillion electron volts. Two detections were even at 1,000 trillion electron volts. (Review 1631)
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- Particle physics is trying to reduce the Universe to as few particles as possible. It is narrowed down to 12 particles. Three of these are neutrinos. Physicists are searching for a violation in the Law of Conservation of mass/energy. (Review 1814)
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- Are their neutrinos that are right handed? Only a few neutrinos interact with the atoms in your body over your entire lifetime. Discovering sterile neutrinos may help explain the source of neutrino mass. There are hundreds of math models working on this problem. (Review 1840)
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- Neutrinos are sub-atomic particles that reside with electrons and protons at the center of atoms. There are three types: electron, muon, tau neutrinos. (Review 1978)
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- There is an experiment that is sending neutrinos through the earth from Illinois to the detector in South Dakota. Neutrinos may acquire their mass through a new undiscovered type of physics. Other particles inside atoms obtain their mass by interacting with the Higgs Field. (Review 2026)
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- The ICECUBE neutrino detector at the South Pole has over 5,000 light sensors to detect neutrinos interacting with atoms in the ice. The array of sensors is designed to plot the direction from which the neutrinos are coming. Astronomers then search for the origin, the source.
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- Neutrinos are neutral particles and travel in a straight line. The source was a blazar, a super massive blackhole at the center of a galaxy. February, 1987, 25 neutrinos were detected in Japan, the U.S., and in Russia. 3 hours later the light came from this exploding supernova. By November x-rays and gamma rays arrived. All created from this star's collapse. 99% of the total explosive energy comes in the form of neutrinos.
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- In September, 2017, ICECUBE detected another high energy neutrino. Then the Swift x-ray telescope detected nine sources of x-rays coming from that same part of the sky. Two days later the Fermi space telescope detected gamma rays coming from the same sources.
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- Optical telescopes identified a source brightening over the past 50 days. Another telescope identified a “blazar” , a huge blackhole emitting jets as it swallowed mass. Radio light detections further identified the source to be the blazar.
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- Gravitational waves were detected by the LIGO observatory resulting from the merger of two blackholes.
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- Astronomers have a whole raft of new detectors used to explore the Universe. Past the electromagnetic spectrum gravity waves and neutrino detectors have been added to the mix. ("Neutrinos at the ends of the Earth", Francis Halzen, October, 2015.)
- The neutrino is a tiny elementary particle that is a billion times more abundant than protons and electrons that make up our normal atoms. Neutrinos are produced in the fusion reactions of our Sun and in the natural radioactive decay of elements in the Earth’s crust.
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- The neutrino is a tiny elementary particle that is a billion times more abundant than protons and electrons that make up our normal atoms. Neutrinos are produced in the fusion reactions of our Sun and in the natural radioactive decay of elements in the Earth’s crust.
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- This may surprise you but your body contains about 20 milligrams of Potassium 40. This is one of these natural radioactive elements. During normal radioactive decay inside your body you are emitting 340,000,000 neutrinos each day. These neutrinos leave your body at light speed and travel to the farthest ends of the Universe.
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- Neutrinos are invisible, they carry no electric charge, and have almost no mass. Consequently, they pass through most everything with no interactions at all. In fact, from all the various sources there are 1,000,000,000,000 neutrinos (trillions) passing through your body every second.
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- Before describing where neutrinos come from I first need to define how we measure them and how we can tell them apart. We know that energy is equal to mass times the speed of light squared (E = mc^2). So, mass can be describe as Energy divided by the speed of light squared (m = E/c^2). One convenient way to measure mass in small particles is in electron volts.
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- One electron volt, one eV, equals the energy of one electron falling through an electrostatic potential difference of one volt. This is a very small amount of energy. 1 ev = 1.6 * 10^-19 joules of energy. One electron volt is the energy needed to lift a grain of sand one centimeter off the surface of Earth. One eV is the energy used in the blink of an eye.
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------------------ There are 18,750,000,000,000,000 eV in an uncontrollable sneeze.
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------------------ A Sneeze = 3*10^-3 joules / 1.6*10^-19 joules/eV = 1.875 * 10^16 eV
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- An electron has a rest mass of 511,000 eV. If the electron disintegrates into pure energy it would yield 1,022,000 eV of energy.
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- A proton has a mass of 938,000,000 eV. One kilogram of mass = 90*10^15 joules. 1 eV/cm^2 = 1.783*10^-36 kilograms. Charged particles in a nuclear bomb explosion range from 300,000 to 3,000,000 eV. A molecule in the air has an average energy of
0.03 eV.
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- Hopefully, these numbers give you some flavor of energy in electron volts. Now we will use this measure to describe the sources of neutrinos:
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- Neutrinos from stars, and from our Sun:
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-------------------------------------- .000006 neutrinos / cm^3 at 20,000,000 eV
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- The sun emits 2*10^38 neutrinos per second. The Earth’s surface receives 40,000,000,000 neutrinos per second per square centimeter. The Sun generates these neutrinos through the fusion of hydrogen into helium. 85% of the Sun’s neutrinos come from two protons combining to form Deuterium nuclei plus a positron and plus an electron neutrino. Deutrium is heavy hydrogen, it is a proton combined with a neutron.
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- Neutrinos from high energy particle accelerators and from nuclear reactors, or from nuclear bombs:
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---------------------------------------- 5*10^20 neutrons per second at 4,000,000 eV
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- A nuclear reactor core will radiate 500,000,000,000,000,000,000 neutrinos each second. Neutrinos from particle accelerators today very with mean energies from 30,000,000 eV to 30,000,000,000 eV.
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- Neutrinos from natural radioactivity in Earth’s crust:
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---------------------------------------- 6,000,000 neutrino / second / centimeter^2
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Natural radioactivity occurs from beta decay of Uranium, Thorium, and Potassium 40. It is equivalent to about 20,000 nuclear plants.
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- Neutrinos from the Big Bang:
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------------------------ 330 neutrinos /cm^3 over the whole Universe at .0004 eV
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- This is very similar to the Cosmic Microwave Background Radiation that was caused by the decoupling of photons from electrons, 300,000 years after the Big Bang that started out as light and now comes to us as microwave energy, 1.4 Ghz at 2.73 degrees Kelvin. (You can convert energy in electron volts to temperature in Kelvin multiplying by 11,605).
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- The Neutrino Cosmic Background comes from decoupling of neutrinos emitted by neutrons about one second after the Big Bang. Before the decoupling neutrinos were absorbed by protons as fast as emitted by neutrons.
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- After one second of cooling the lower temperature prevented the protons from absorbing neutrinos and the neutron emitted neutrinos were free. Today, they are very low energy, only .0004 eV. By comparison, on average, there are 330,000,000 neutrinos, 0.5 protons, and 1,000,000,000 photons in each cubic meter of the Universe
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- Neutrinos from Supernova explosions:
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--------------------------------------------- 0.0002 neutrino / cm^3
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- These were first detected in the Supernova 1987a in the Magellan Cloud exploding 150,000 lightyears from Earth.
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- Neutrinos from Cosmic Rays:
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- When a Cosmic Ray penetrates Earth’s atmosphere hitting a gas molecule it shatters and generates a shower of elementary particles. Cosmic Rays are hydrogen nuclei (protons) traveling at nearly the speed of light. Among the particles are atmospheric neutrinos.
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- The sum of all of these sources create trillions of neutrinos traveling through your body, and everything else, every second at the speed of light. 400,000,000,000 from the Sun, 50,000,000 from natural radioactivity, 100,000,000 from nuclear plants all around the world.
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- These neutrinos are very difficult to detect and to measure. The most successful experiment in detecting the very high energy neutrinos is occurring in the Antarctic. Here experiments called AMANDA II and ICECUBE have used hot water drills to drill deep holes into the ice. They have sunk 677 glass optical modules arranged on 19 cables down as deep as 1,500 meters. They form an array of detectors 500 meters high by 120 meters in diameter.
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- The glass modules work like light bulbs in reverse. They detect light signals and send electric data up to computers on the surface. The light signals come from looking down through the Earth into the Northern Hemisphere. Only neutrinos can easily traverse through the Earth, yet some do crash in to ice atom nuclei scattering other elementary particles, called muons.
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- These muons travel in water faster than light travels in water (ice). (Light travels about 75% as fast in water as it does in a vacuum.) The faster muons create a shockwave much like breaking the sound barrier, that in turn creates a blue streak of light, called Cherenkov Radiation.
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- It is these streaks of light that are detected. From the array of detectors the direction and the energy levels of the neutrinos can be calculated. Neutrinos have been detected that are 100 times more energy than we can create in our most powerful particle accelerators.
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- ICECUBE is planning to expand the array to 4,800 optical modules covering one cubic kilometer. This instrument will be , in effect, a neutrino telescope looking down through the Earth into the Northern Hemisphere to learn where these high energy neutrinos are coming from.
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- By “seeing” with neutrinos it will allow us to see things we have never seen before. We understand our Universe by seeing photons. But, photons have disadvantages, they interact with matter, they scatter in gas and dust, they bend with gravity, they slow down in different mediums, they change wavelength with velocity. Neutrinos can avoid some of this interference in what we see. If we can learn to see with neutrinos we will surely discover many new things unseen before.
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- By looking at the neutrinos emitted from the Sun we discovered only 1/3 as many as our calculations showed should be there. The Sun burns 600,000,000 tons of hydrogen into helium every second, so we know how many neutrinos are produced. From this study we have learned that there are really three types of neutrinos:
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------------------- Electron neutrinos < 2.5 eV
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------------------- Muon neutrinos < 170,000 eV
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------------------- Tau neutrinos < 18,000,000 eV
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- We do not know the exact masses for these neutrinos but we have learned that neutrinos oscillate between the three different types. Neutrinos leave the Sun as electron neutrinos. In the 8 minutes, traveling at the speed of light, they arrive at Earth with 2/3rds changed into the other types and undetected.
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- On March 30, 2006 Fermi National Labs announced the discovery of the tau neutrino. Electron neutrinos were discovered in 1956 and muon neutrinos in 1962. Now, all three types have been produced.
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------------------------------ The history of neutrinos:
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1927 - The spectrum of beta decay as discovered to be continuous
1930 - To account for energy conservation in beta decay Wolfgang Pauli hypothesized the existence of neutrinos.
1932 - neutron is discovered
1946 - neutrino to accompany muon is proposed.
1956 - neutrinos discovered coming from nuclear reactors.
1957 - neutrinos found to be left-handed. Neutrino oscillation proposed.
1962 - neutrinos come in 3 flavors proposed. Muon neutrino discovered.
1965 - neutrinos discovered in natural radioactive decay in gold mine in South Africa.
1968 - solar neutrinos detected, only one third number expected.
1976 - tau lepton discovered.
1987 - neutrinos discovered from Supernova 1987a.
1989 - neutrinos determined to come in three species, electron, muon and tau.
2000 - tau particles produced in Fermilab.
2002 - neutrino oscillations between 3 species explains number of solar neutrinos detected.
2006 - Fermi lab announced tau neutrino was discovered.
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- Neutrinos are Fermions which are elementary particles having a spin of ½. Spin is the angular momentum of a rotating particle. Fermions include Leptons, quarks, and baryons. Neutrinos are also Leptons. Leptons do not partake in the Strong Nuclear Force interactions. They interact only through the Weak Nuclear Force. There are six types of Leptons: electron, muon, tau, electron neutrino, muon neutrino, and tau neutrino.
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------------------------------------ Other reviews available:
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- 2973 - NEUTRINOS - the littlest particles! Many more discoveries are needed to explain neutrinos. A detector in the ice at the South Pole may make these new neutrino discoveries. Another experiment is sending neutrinos from Illinois to South Dakota. Neutrinos are a billion times more abundant than electrons.
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- 2938 - NEUTRINO - and cosmic ray discoveries? - We all know that all material is made of atoms. Atoms combine into elements and molecules to create our material world. But what makes up atoms? You may have already learned that they are made up of electrons and protons. Now we enter the world of Particle Physics, what makes up protons?
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- 2835 - NEUTRINOS - a thermal history. If you could see neutrinos you could see back in time to 1 second after the Big Bang. To see with visible light, we see with photons. And, because the Universe is expanding seeing with visible light, near the red end of the spectrum, we can see back to when the Universe was 2.3 billion years old,
17 % its current size.
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- 2762 - NEUTRINOS - experiments to learn more? The difficult-to-detect neutrino seems to undergo a strange identity-flipping process, and if this reaction occurs differently between neutrinos and antineutrinos, then this process, called neutrino oscillation, could help physicists explain why matter dominates over antimatter.
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- 2619 - NEUTRINOS - and other mysterious particles? Our best model of particle physics is being challenged with the weirdness a series of strange events in Antarctica. Strange results from laboratory experiments suggest a ghostly new species of neutrinos beyond the three described in the Standard Model. And the universe seems full of dark matter that no particle in the Standard Model can explain.
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- 2223 - Astronomers have learned much more about the Universe with their “microwave telescopes”. They have determined the Universe to be 13,800,000,000 years old. They have determined that only 5% or the Universe is visible or ordinary matter. The rest is Dark Matter (25%) and Dark Energy (70%) . To learn more astronomers want to be able to use “neutrino telescopes” and “gravity wave telescopes”.
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- 2131 - Neutrinos - The Little Neutral Ones. The neutrino is a tiny elementary particle that is a billion times more abundant than protons and electrons that make up our normal atoms. Neutrinos are produced in the fusion reactions of our Sun and in the natural radioactive decay of elements in the Earth’s crust. Potassium 40 in your body is emitting 340,000,000 neutrinos every day. This review contains the history of discoveries of neutrinos.
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- 2093 - Neutrinos - What have we learned? - Neutrinos are the smallest atomic particles. If we could see neutrinos they would be exceptional probes into our environment. Neutrinos are produced in fusions reactions in the Sun and stars, and in radioactive decay in the earth's crust. The ICECUBE neutrino detector at the South Pole has over 5,000 light sensors to detect neutrinos interacting with atoms in the ice.
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- 2026 - Many more discoveries are needed to explain neutrinos. A detector in the ice at the South Pole may make these new neutrino discoveries. Another experiment is sending neutrinos from Illinois to South Dakota. Neutrinos are a billion times more abundant than electrons.
January 26, 2021 NEUTRINOS 2093 2131 3006
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