- 3034 - NEUTRINO DISCOVERIES - Neutrinos have a newly discovered method of interacting with matter, opening up ways to find them. The neutrino is a confounding little particle that is believed to have played a major role in the evolution of our Universe.
--------------------------- 3034 - NEUTRINO DISCOVERIES - Neutrinos possess very little mass, have no charge, and interact with other particles only through the weak nuclear force and gravity. Finding evidence of their interactions is extremely difficult and requires advanced facilities that are shielded to prevent interference.
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- The Oak Ridge National Laboratory (ORNL) has an international team of researchers conducting the COHERENT particle physics experiment. COHERENT achieved a major breakthrough when they found the first evidence of a new kind of neutrino interaction, which effectively demonstrates a process known as “coherent elastic neutrino-nuclear scattering” (CEvNS).
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- According to “The Standard Model of Particle Physics“, neutrinos are “leptons“, an elementary particle similar to an electron, but with no electric charge and very little mass.
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- Neutrinos are created through radioactive decay, stellar fusion, supernovae, and as a byproduct of the Big Bang. They are believed to be the most abundant particles in the Universe.
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- The CEvNS process comes down to neutrinos colliding with the much-larger nucleus of an element, which results in a tiny transfer of energy and causes the nucleus to recoil almost imperceptibly.
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- The process was first predicted in 1973 but evaded detection because of the tiny amounts of energy and motion involved. This changed in 2017 when members of the COHERENT collaboration used the “Spallation Neutron Source” SNS to measure the CEvNS process for the first time.
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- Scientists observed neutrinos generated by the SNS as they interacted with heavier cesium and iodine nuclei. The team observed neutrinos as they collided with even smaller argon nuclei, which caused even tinier levels of recoil.
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- The Standard Model of Particle Physics predicts coherent elastic scattering of neutrinos off nuclei. Seeing the neutrino interaction with argon, the lightest nucleus for which it has been measured, confirms the earlier observation from heavier nuclei. Measuring the process precisely establishes constraints on alternative theoretical models.
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- In addition to being the smallest neutrino detector in the world, the SNS accelerator-based system is also the world’s brightest source of pulsed neutron beams. This consists of protons that are fired at atoms of mercury, a process which smashes them apart to produce massive amounts of neutrons and neutrinos as a by-product.
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- These neutrinos are used in a dedicated neutrino laboratory beneath the SNS, an experiment known as “Neutrino Alley” developed by the COHERENT team. This alley is outfitted with highly-sensitive CENNS-10 detectors, which rely on cesium iodide scintillator crystals to detect tiny light signals produced by subatomic interactions.
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- This made the experiment even more sensitive, to the point that it could provide data on even tinier collisions. The analysis of which revealed 159 CEvNS events, which is consistent with the Standard Model prediction. In the future, the collaboration team hopes to scale their experiment so they can observe 25 times as many CEvNS events per year.
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- hoping to observe CEvNS on a variety of nuclei, the team plans to install an even bigger 10-ton (9 metric ton) liquid argon detector at the SNS’s Second Target Station. There are also plans for adding a 16-kg (~35 lbs) detector based on germanium nuclei (bigger than argon but smaller than cesium and iodine) to Neutrino Alley next year.
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- Astrophysicists could use this data to determine the density of neutron stars, providing another way for investigating physics under the most extreme and exotic of domains.
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- There are things the Standard Model just doesn’t explain. We suspect that in these small places where the model might break down, answers to big questions about the nature of the universe, antimatter and dark matter. ------ Other Reviews:
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- 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.
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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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February 7, 2021 NEUTRINO DISCOVERIES 3034
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--------------------- --- Monday, February 8, 2021 ---------------------------
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