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--- In 1987 an amateur astronomer in Chile discovered the closest supernova in the large majority and it cloud. The large majority and cloud is a satellite galaxy orbiting the Milky Way. There are 23 such galaxies in our local group of galaxies.
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--- One supernova can briefly outshine 1 billion stars
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--- A few hours later on the same night an amateur astronomer in New Zealand made the same discovery. The astronomers around the world were soon studying this unique event so close to home. The supernova is the first one to occur in our local group of galaxies since the telescope was invented 400 years ago.
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--- Particle physicists were busy studying this as well. Theory tells us that a bath of neutrinos proceeds the photons when a massive star collapses into a supernova. The neutral particles get free of the charged plasma first.
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--- The photo tubes in the Kamiokande underground experiment in Japan detected 11 flashes of neutrino impacts lasting several seconds. These detections occurred nearly 3 hours before the first optical sighting.
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--- A second neutrino detector registered 8 flashes at exactly the same time. It was located in a salt mine near Cleveland, Ohio.
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--- A third observatory in Russia recorded 5 neutrinos
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--- These 24 neutrinos were only a small part of the billions of neutrinos that swept through our planet as result of this exploding supernova.
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--- This event was the first time neutrinos were detected from an astronomical source other than our Sun.
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--- The energies calculated after these neutrino detections match the theoretical calculations predicted from this size supernova explosion.
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--- The mass of these neutrinos must be very small because the calculations showed they were traveling at nearly the speed of light. With this conclusion science does not see the neutrino population in the universe accounting for Dark Matter, despite their prodigious numbers the are too near massless.
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--- In our make Milky Way galaxy supernovae have occurred in 1604 and 1572 witness by Johannes Kepler and Tycho Brahe. Astronomers predict that on average the Milky Way galaxy should see a few supernovae every 100 years. Detecting a burst of neutrinos should be able to make these discoveries even though light waves are blocked by interstellar dust.
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--- Astronomers now have a worldwide supernova early warning system, SNEWS, to alert the entire community as soon as a detection is made. The hope is that neutrino detections being first would allow radio, microwave, x-ray, as well as light detections soon thereafter.
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--- Astronomers predict that if the neutrino burst lasts for 10 seconds or so the supernova collapse was to a neutron star. If the burst comes to a sudden halt in just a few seconds that a blackhole was formed.
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--- Current neutrino detectors are only sensitive to the Electron Neutrino Antimatter. Neutrinos exist in three flavors, Electron, Muon, and Tau. Because we can only see one flavor we in effect get a black and white photo of a full-color image. To resolve this problem work is progressing on developing detectors that can detect all of these two flavors as well as their anti-neutrino equivalents.
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--- Since neutrinos interact only very rarely with matter, the enormous flux of solar neutrinos racing to the Earth is sufficient to produce only 1 interaction for 1,036 target atoms, and each interaction produces only a few photons. The observation of neutrino interactions requires a large detector mass along with a sensitive amplification system.
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--- Given the very weak signal sources background noise must be reduced as much as possible. Detectors must be shielded by a large mass so they are constructed deep underground, underwater, or, under ice. They record upward going muons in neutrino interactions. Upward because no other known particle can traverse the entire earth. The detector must be at least one kilometer deep to suppress downward traveling muons. The background noise of extraterrestrial neutrons interacting in the Earth’s atmosphere provides a standard calibration source.
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--- Sources of radioactive isotopes must also be controlled as they produce energetic particles when they decay. The detectors consists of an array of photomultiplier tubes housed in transparent pressure spheres which are suspended in large volume of water, or ice. The photomultiplier tubes record the arrival time and amplitude of Cerenkov light emitted by muons. The trajectory can then usually be recon-structured if at least three interactions are detected as a single event.
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--- Unfortunately even these advances are able to detect neutrinos coming from sources only half the distance across our galaxy. The hope is that detectors can be made sensitive enough to detect neutrinos emitted from sources in other galaxies.
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--- Andromeda galaxy is only 2,500,000 light-years away. That would be a good target.
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- Betelgeuse and at Eta Carinae are two giant aging stars that might appear supernova any day now. Astronomically speaking “any day now” might occur any time over several hundred thousand years. Do you see why supernova 1987 is so special.
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--- The newest neutrino detector is the ICECUBE detector installed deep in the ice of the Antarctic. This detector has already observed 28 extremely high-energy events that are solid evidence of astrophysical neutrinos outside our solar system.
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--- Early evidence from these neutrino measurements are that something is accelerating particles to energies above 50 trillion electron volts. Two of these detections were measured at 1,000 trillion electron volts.
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--- These cosmic accelerators are 40 million times more powerful than our Large Hadron Collider in CERN, Switzerland.
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--- Cosmic rays are electrically charged particles, usually protons, but, in some cases , heavy nuclei, even iron. Being charged particles they spiral through magnetic fields to disguising wherever they originated from.
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--- Neutrinos are neutral particles. They tend to travel in a straight line and travel virtually through everything in their path. The only way to detect neutrinos is through their interaction with the Weak Nuclear Force. They are unaffected by the electromagnetic force.
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--- The ICECUBE Observatory has 5,160 basketball size detectors, digital optical modules, suspended along 86 lines down a cubic kilometer of clear ice. They start one a half kilometers below the icy Antarctica surface. An announcement will be made shortly stay tuned.
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(1) Other reviews available on neutrinos: 1608, 1589, 1139, 632, 630,
1219 is on ICECUBE neutrinos
1511 is on Sterile neutrinos.
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RSVP, with comments, suggestions, corrections. Index of reviews available ---
--- Some reviews are at: -------------------- http://jdetrick.blogspot.com -----
---- email request for copies to: ------- jamesdetrick@comcast.net ---------
---- https://plus.google.com/u/0/ , “Jim Detrick” ----- www.facebook.com ---
---- www.twitter.com , --- 707-536-3272 ---- Tuesday, January 7, 2014 ---
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