Posted on 07/13/2018 12:09:03 PM PDT by ETL
The so-called "ghost particle" was trapped by researchers in a giant ice cube at the South Pole.
It's actually a high-energy neutrino, and is the first of its type ever detected by scientists.
Importantly, researchers believe they've tracked its likely source: a supermassive black hole that emits light and cosmic rays.
The black hole is roughly four billion light years away, at the centre of a completely different galaxy.
The discovery, reported in the journal Science, solves a major scientific riddle.
Part of the problem with these "ghost particles" is that they're in no short supply, but we've never really understood them.
They shoot around the universe at the speed of light, having almost no mass, and passing through almost anything.
They're so common that around 65million of these particles pass through every square centimetre of your body each second.
The fact that they pass through matter so easily makes them difficult to track, and very tricky to actually capture.
Here's what you need to know...
But scientists were able to snatch one, and then identify its source – because the particle will have travelled in a completely straight line from its origin to Earth.
"Neutrinos rarely interact with matter," said Professor Paul O'Brien, a member of the international team of astronomers from the University of Leicester.
"To detect them at all from the cosmos is amazing, but to have a possible source identified is a triumph.
"This result will allow us to study the most distant, powerful energy sources in the universe in a completely new way."
Astronomers first set up their giant neutrino trap – called 'IceCube' – seven years ago, around a giant ice cube sunk a mile beneath the South Pole.
Then, on September 22 last year, researchers were able to detect a neutrino's presence in the chilly 'IceCube' trap.
A grid of more than 5,000 super-sensitive sensors picked up blue "Cherenkov" light that was emitted as the neutrino interacted with the ice.
Scientists had previously spotted 81 such flashes without finding the associated neutrinos.
But then, finally, luck was on the science's side when it came to tracking the particle's origin.
A telescope orbiting Earth picked up a burst of radiation coming from the same direction as the neutrino.
This radiation was burst was a blazar, a special type of galaxy that contains a supermassive black hole.
” Oh look!! there is a oxygen bubble in this worthless rock.” Happens all the time. Just google “ life on Mars” , It is all to justify spending money we don’t have. I call it “work fare for scientist”.
So, how do you "trap" something that passes through everything?
If one particle in ice changes your view of the Universe, then your theory of the Universe was horrendously wrong.
...
This is the first example of neutrino astronomy. That’s what they mean by a new view of the Universe. They shouldn’t have put something so vague in the title.
>>So, how do you “trap” something that passes through everything?
From Wikipedia...
Neutrino detector
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.[1]
The field of neutrino astronomy is still very much in its infancy – the only confirmed extraterrestrial sources so far are the Sun and Supernova 1987A.
Neutrino observatories will “give astronomers fresh eyes with which to study the universe.”[2]
Various detection methods have been used. Super Kamiokande is a large volume of water surrounded by phototubes that watch for the Cherenkov radiation emitted when an incoming neutrino creates an electron or muon in the water.
The Sudbury Neutrino Observatory is similar, but uses heavy water as the detecting medium. Other detectors have consisted of large volumes of chlorine or gallium which are periodically checked for excesses of argon or germanium, respectively, which are created by neutrinos interacting with the original substance.
MINOS uses a solid plastic scintillator watched by phototubes; Borexino uses a liquid pseudocumene scintillator also watched by phototubes; and the A detector uses a liquid scintillator watched by avalanche photodiodes.
The proposed acoustic detection of neutrinos via the thermoacoustic effect is the subject of dedicated studies done by the ANTARES, IceCube, and KM3NeT collaborations.
Theory
Neutrinos are omnipresent in nature such that every second, tens of billions of them “pass through every square centimetre of our bodies without us ever noticing.”[3]
Many were created during the big bang and others are generated by nuclear reactions inside stars, planets, and other interstellar processes[4].
Some may also originate from events in the universe such as “colliding black holes, gamma ray bursts from exploding stars, and/or violent events at the cores of distant galaxies,” according to speculation by scientists.[5]
Despite how common they are, neutrinos are extremely “difficult to detect” due to their low mass and lack of electric charge. Unlike other particles, neutrinos only interact via gravity and the neutral current (involving the exchange of a Z boson) or charged current (involving the exchange of a W boson) weak interactions.
As they have only a “smidgen of rest mass” according to the laws of physics, perhaps less than a “millionth as much as an electron,”[1] the gravitational force caused by neutrinos has proven too weak to detect, leaving the weak interaction as the main method for detection:
In a neutral current interaction, the neutrino enters and then leaves the detector after having transferred some of its energy and momentum to a target particle. If the target particle is charged and sufficiently light (e.g. an electron), it may be accelerated to a relativistic speed and consequently emit Cherenkov radiation, which can be observed directly.
All three neutrino flavors can participate regardless of the neutrino energy.
However, no neutrino flavor information is left behind.
In a charged current interaction, a high-energy neutrino transforms into its partner lepton (electron, muon, or tau).[6] However, if the neutrino does not have sufficient energy to create its heavier partner’s mass, the charged current interaction is unavailable to it.
Neutrinos from the sun and from nuclear reactors have enough energy to create electrons. Most accelerator-based neutrino beams can also create muons, and a few can create taus.
A detector which can distinguish among these leptons can reveal the flavor of the incident neutrino in a charged current interaction. Because the interaction involves the exchange of a charged boson, the target particle also changes character (e.g., neutron; proton).
Detection techniques...
Scintillators
Antineutrinos were first detected near the Savannah River nuclear reactor in 1956. Frederick Reines and Clyde Cowan used two targets containing a solution of cadmium chloride in water. Two scintillation detectors were placed next to the cadmium targets.
Antineutrinos with an energy above the threshold of 1.8 MeV caused charged current “inverse beta-decay” interactions with the protons in the water, producing positrons and neutrons. The resulting positron annihilations with electrons created pairs of coincident photons with an energy of about 0.5 MeV each, which could be detected by the two scintillation detectors above and below the target.
The neutrons were captured by cadmium nuclei resulting in delayed gamma rays of about 8 MeV that were detected a few microseconds after the photons from a positron annihilation event.
This experiment was designed by Cowan and Reines to give a unique signature for antineutrinos, to prove the existence of these particles. It was not the experimental goal to measure the total antineutrino flux.
The detected antineutrinos thus all carried an energy greater 1.8 MeV, which is the threshold for the reaction channel used (1.8 MeV is the energy needed to create a positron and a neutron from a proton).
Only about 3% of the antineutrinos from a nuclear reactor carry enough energy for the reaction to occur.
A more recently built and much larger KamLAND detector used similar techniques to study oscillations of antineutrinos from 53 Japanese nuclear power plants.
A smaller, but more radiopure Borexino detector was able to measure the most important components of the neutrino spectrum from the Sun, as well as antineutrinos from Earth and nuclear reactors.
Radiochemical methods
Chlorine detectors, based on the method suggested by Bruno Pontecorvo, consist of a tank filled with a chlorine containing fluid such as tetrachloroethylene. A neutrino converts a chlorine-37 atom into one of argon-37 via the charged current interaction.
The threshold neutrino energy for this reaction is 0.814 MeV. The fluid is periodically purged with helium gas which would remove the argon. The helium is then cooled to separate out the argon, and the argon atoms are counted based on their electron capture radioactive decays.
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. Neutrinos were thus detected by measuring the radioactive decay of germanium. This latter method is nicknamed the “Alsace-Lorraine” technique because of the reaction sequence (gallium-germanium-gallium) involved. Gallium and germanium are named after France and Germany, respectively, and ownership of the Alsace-Lorraine territory has historically been a point of contention between France and Germany, thus the nickname of the technique.
These radiochemical detection methods are useful only for counting neutrinos; no neutrino direction or energy information is available. The SAGE experiment in Russia used about 50 tons, and the GALLEX/GNO experiments in Italy about 30 tons, of gallium as reaction mass.
This experiment is difficult to scale up due to the prohibitive cost of gallium. Larger experiments have therefore turned to a cheaper reaction mass.
Cherenkov detectors
“Ring-imaging” Cherenkov detectors take advantage of a phenomenon called Cherenkov light. Cherenkov radiation is produced whenever charged particles such as electrons or muons are moving through a given detector medium somewhat faster than the speed of light in that medium.
In a Cherenkov detector, a large volume of clear material such as water or ice is surrounded by light-sensitive photomultiplier tubes.
A charged lepton produced with sufficient energy and moving through such a detector does travel somewhat faster than the speed of light in the detector medium (although somewhat slower than the speed of light in a vacuum).
The charged lepton generates a visible “optical shockwave” of Cherenkov radiation. This radiation is detected by the photomultiplier tubes and shows up as a characteristic ring-like pattern of activity in the array of photomultiplier tubes.
As neutrinos can interact with atomic nuclei to produce charged leptons which emit Cherenkov radiation, this pattern can be used to infer direction, energy, and (sometimes) flavor information about incident neutrinos.
Two water-filled detectors of this type (Kamiokande and IMB) recorded a neutrino burst from supernova SN 1987A.[7] Scientists detected 19 neutrinos from an explosion of a star inside the Large Magellanic Cloud—only 19 out of the billion trillion trillion trillion trillion neutrinos emitted by the supernova.[1]
The Kamiokande detector was able to detect the burst of neutrinos associated with this supernova, and in 1988 it was used to directly confirm the production of solar neutrinos. The largest such detector is the water-filled Super-Kamiokande. This detector uses 50,000 tons of pure water surrounded by 11,000 photomultiplier tubes buried 1 km underground.
The Sudbury Neutrino Observatory (SNO) uses 1,000 tonnes of ultrapure heavy water contained in a 12-metre-diameter vessel made of acrylic plastic surrounded by a cylinder of ultrapure ordinary water 22 metres in diameter and 34 metres high.[6] In addition to the neutrino interactions visible in a regular water detector, a neutrino can break up the deuterium in heavy water.
The resulting free neutron is subsequently captured, releasing a burst of gamma rays that can be detected. All three neutrino flavors participate equally in this dissociation reaction.
The MiniBooNE detector employs pure mineral oil as its detection medium. Mineral oil is a natural scintillator, so charged particles without sufficient energy to produce Cherenkov light still produce scintillation light. Low-energy muons and protons, invisible in water, can be detected.
Located at a depth of about 2.5 km in the Mediterranean Sea, the ANTARES (Astronomy with a Neutrino Telescope and Abyss environmental RESearch) is fully operational since May 30, 2008. Consisting of an array of twelve separate 350-meter-long vertical detector strings 70 meters apart, each with 75 photomultiplier optical modules, this detector uses the surrounding sea water as the detector medium.
The next generation deep sea neutrino telescope KM3NeT will have a total instrumented volume of about 5 km3. The detector will be distributed over three installation sites in the Mediterranean. Implementation of the first phase of the telescope was started in 2013.
The Antarctic Muon And Neutrino Detector Array (AMANDA) operated from 1996 to 2004. This detector used photomultiplier tubes mounted in strings buried deep (1.5–2 km) inside Antarctic glacial ice near the South Pole. The ice itself is the detector medium.
The direction of incident neutrinos is determined by recording the arrival time of individual photons using a three-dimensional array of detector modules each containing one photomultiplier tube. This method allows detection of neutrinos above 50 GeV with a spatial resolution of approximately 2 degrees.
AMANDA was used to generate neutrino maps of the northern sky to search for extraterrestrial neutrino sources and to search for dark matter. AMANDA has been upgraded to the IceCube observatory, eventually increasing the volume of the detector array to one cubic kilometer.[8]
Radio detectors
The Radio Ice Cherenkov Experiment uses antennas to detect Cherenkov radiation from high-energy neutrinos in Antarctica. The Antarctic Impulse Transient Antenna (ANITA) is a balloon-borne device flying over Antarctica and detecting Askaryan radiation produced by ultra-high-energy neutrinos interacting with the ice below.
Tracking calorimeters
Tracking calorimeters such as the MINOS detectors use alternating planes of absorber material and detector material. The absorber planes provide detector mass while the detector planes provide the tracking information. Steel is a popular absorber choice, being relatively dense and inexpensive and having the advantage that it can be magnetised.
The ... proposal suggests eliminating the absorber planes in favor of using a very large active detector volume. The active detector is often liquid or plastic scintillator, read out with photomultiplier tubes, although various kinds of ionisation chambers have also been used.
Tracking calorimeters are only useful for high-energy (GeV range) neutrinos. At these energies, neutral current interactions appear as a shower of hadronic debris and charged current interactions are identified by the presence of the charged lepton’s track (possibly alongside some form of hadronic debris.)
A muon produced in a charged current interaction leaves a long penetrating track and is easy to spot. The length of this muon track and its curvature in the magnetic field provide energy and charge .... information.
An electron in the detector produces an electromagnetic shower which can be distinguished from hadronic showers if the granularity of the active detector is small compared to the physical extent of the shower. Tau leptons decay essentially immediately to either pions or another charged lepton and cannot be observed directly in this kind of detector. (To directly observe taus, one typically looks for a kink in tracks in photographic emulsion.)
Coherent Recoil Detector
At low energies, a neutrino can scatter from the entire nucleus of an atom, rather than the individual nucleons, in a process known as “Coherent Neutral Current Neutrino-Nucleus Elastic Scattering”.[9] This effect has been used to make an extremely small neutrino detector.[10][11][12] Unlike most other detection methods, coherent scattering does not depend on the flavor of the neutrino.
Background suppression
Most neutrino experiments must address the flux of cosmic rays that bombard the Earth’s surface.
The higher-energy (>50 MeV or so) neutrino experiments often cover or surround the primary detector with a “veto” detector which reveals when a cosmic ray passes into the primary detector, allowing the corresponding activity in the primary detector to be ignored (”vetoed”).
For lower-energy experiments, the cosmic rays are not directly the problem. Instead, the spallation neutrons and radioisotopes produced by the cosmic rays may mimic the desired signals. For these experiments, the solution is to place the detector deep underground so that the earth above can reduce the cosmic ray rate to acceptable levels.
https://en.wikipedia.org/wiki/Neutrino_detector
Good question, btw.
This had me going until I thought about it for a moment:
whenever charged particles such as electrons or muons are moving through a given detector medium somewhat faster than the speed of light in that medium.
I wonder about the defense/military applications of this technology. It would seemingly give us the ability to identify small amounts of radioactivity anywhere on earth as well as the ability to monitor nuclear reactions.
What ever you do, Egon: Don’t cross the streams.
Peter: Why?
Egon: It would be bad.
Peter: I’m fuzzy on the whole good/bad thing. What do you mean “bad”?
Egon: Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.
Raymond: Total protonic reversal.
Peter: That’s bad. Okay. Alright, important safety tip, thanks Egon.
“moving through a medium faster than light”
Are they referring to the quantum mechanics phenomenon of “tunneling” ?
Lol! Sounds like good advice, I think. What’s it from, some movie or TV show?
Maybe these particles are not affected by the material dielectric or refractive value, so they are effectively moving faster than photons while in the stuff?
Most of them can pass through he earth but there is a an extremely tiny chance that a neutrino can interact with something in a detectable way and there are so many trillions of neutrinos that every once in a while one of them does.
That was from the 1984 movie ghostbusters with dan ackroyd, bill Murray, Harold Ramis. Good movie and good advice for dealing with particles. ;)
Because light interacts with the atoms in clear materials, it effectively moves more slowly. Particles that are going faster than the speed of light in these materials can produce a kind of shock wave that appears as blue light, radiated in a cone around the direction of travel.
Ok, this I'm somewhat familiar with. I've read in articles that neutrinos from distant stars can reach earth before photons due to this or a similar phenomenon. Might be that the photons take longer to escape the star.
I think what I just described is in regards to supernova explosions, where neutrinos reach earth before the photons do.
A high-energy neutrino has been traced to its galactic birthplace
July 12, 2018
https://www.sciencenews.org/article/high-energy-neutrinos-blazar-icecube?tgt=nr
50 years ago, neutrinos ghosted scientists
July 12, 2018
https://www.sciencenews.org/article/50-years-ago-neutrinos-ghosted-scientists?tgt=nr
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