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  • richardmitnick 5:34 pm on August 30, 2018 Permalink | Reply
    Tags: , Borexino observatory, , , , , DarkSide experiment, Davide D’Angelo-physical scientist, , , , , , , Pobbile dark matter candidates-axions gravitinos Massive Astrophysical Compact Halo Objects (MACHOs) and Weakly Interacting Massive Particles (WMIPs.)), SABRE-Sodium Iodide with Active Background Rejection Experiment, , Solar neutrinos-recently caught at U Wisconsin IceCube at the South Pole, , Super-Kamiokande Collaboration, , , , WIMPs that go by names like the gravitino sneutrino and neutralino   

    From Gran Sasso via Motherboard: “The New Hunt for Dark Matter Is Taking Place Under a Mountain” 

    From Gran Sasso

    via

    Motherboard

    1

    Aug 30 2018
    Daniel Oberhaus

    Davide D’Angelo wasn’t always interested in dark matter, but now he’s at the forefront of the hunt to find the most elusive particle in the universe.

    About an hour outside of Rome there’s a dense cluster of mountains known as the Gran Sasso d’Italia. Renowned for their natural beauty, the Gran Sasso are a popular tourist destination year round, offering world-class skiing in the winter and plenty of hiking and swimming opportunities in the summer. For the 43-year old Italian physicist Davide D’Angelo, these mountains are like a second home. Unlike most people who visit Gran Sasso, however, D’Angelo spends more time under the mountains than on top of them.

    It’s here, in a cavernous hall thousands of feet beneath the earth, that D’Angleo works on a new generation of experiments dedicated to the hunt for dark matter particles, an exotic form of matter whose existence has been hypothesized for decades but never proven experimentally.

    Dark matter is thought to make up about 27 percent of the universe and characterizing this elusive substance is one of the most profound problems in contemporary physics. Although D’Angelo is optimistic that a breakthrough will occur in his lifetime, so was the last generation of physicists. In fact, there’s a decent chance that the particles D’Angelo is looking for don’t exist at all. Yet for physicists probing the fundamental nature of the universe, the possibility that they might spend their entire career “hunting ghosts,” as D’Angelo put it, is the price of advancing science.

    WHAT’S UNDER THE ‘GREAT STONE’?

    In 1989, Italy’s National Institute for Nuclear Physics opened the Gran Sasso National Laboratory, the world’s largest underground laboratory dedicated to astrophysics. Gran Sasso’s three cavernous halls were purposely built for physics, which is something of a luxury as far as research centers go. Most other underground astrophysics laboratories like SNOLAB are ad hoc facilities that repurpose old or active mine shafts, which limits the amount of time that can be spent in the lab and the types of equipment that can be used.


    SNOLAB, Sudbury, Ontario, Canada.

    Buried nearly a mile underground to protect it from the noisy cosmic rays that bathe the Earth, Gran Sasso is home to a number of particle physics experiments that are probing the foundations of the universe. For the last few years, D’Angelo has divided his time between the Borexino observatory and the Sodium Iodide with Active Background Rejection Experiment (SABRE), which are investigating solar neutrinos and dark matter, respectively.

    Borexino Solar Neutrino detector

    SABRE experiment at INFN Gran Sasso

    2
    Davide D’Angelo with the SABRE proof of concept. Image: Xavier Aaronson/Motherboard

    Over the last 100 years, characterizing solar neutrinos and dark matter was considered to be one of the most important tasks of particle physics. Today, the mystery of solar neutrinos is resolved, but the particles are still of great interest to physicists for the insight they provide into the fusion process occurring in our Sun and other stars. The composition of dark matter, however, is still considered to be one of the biggest questions in particle physics. Despite the radically different nature of the particles, they are united insofar as they both can only be discovered in environments where the background radiation is at a minimum: Thousands of feet beneath the Earth’s surface.

    “The mountain acts as a shield so if you go below it, you have so-called ‘cosmic silence,’” D’Angelo said. “That’s the part of my research I like most: Going into the cave, putting my hands on the detector and trying to understand the signals I’m seeing.”

    After finishing grad school, D’Angelo got a job with Italy’s National Institute for Nuclear Physics where his research focused on solar neutrinos, a subatomic particle with no charge that is produced by fusion in the Sun. For the better part of four decades, solar neutrinos [recently caught at U Wisconsin IceCube at the South Pole] were at the heart of one of the largest mysteries in astrophysics.

    IceCube neutrino detector interior


    U Wisconsin ICECUBE neutrino detector at the South Pole

    The problem was that instruments measuring the energy from solar neutrinos returned results much lower than predicted by the Standard Model, the most accurate theory of fundamental particles in physics.

    Given how accurate the Standard Model had proven to be for other aspects of cosmology, physicists were reluctant to make alterations to it to account for the discrepancy. One possible explanation was that physicists had faulty models of the Sun and better measurements of its core pressure and temperature were needed. Yet after a string of observations in the 60s and 70s demonstrated that the models of the sun were essentially correct, physicists sought alternative explanations by turning to the neutrino.

    A TALE OF THREE NEUTRINOS

    Ever since they were first proposed by the Austrian physicist Wolfgang Pauli in 1930, neutrinos have been called upon to patch holes in theories. In Pauli’s case, he first posited the existence of an extremely light, chargeless particle as a “desperate remedy” to explain why the law of the conservation of energy appeared to be violated during radioactive decay. Three years later, the Italian physicist Enrico Fermi gave these hypothetical particles a name. He called them “neutrinos,” Italian for “little neutrons.”

    A quarter of a century after Pauli posited their existence, two American physicists reported the first evidence of neutrinos produced in a fission reactor. The following year, in 1957, Bruno Pontecorvo, an Italian physicist working in the Soviet Union, developed a theory of neutrino oscillations. At the time, little was known about the properties of neutrinos and Pontecorvo suggested that there might be more than one type of neutrino. If this were the case, Pontecorvo theorized that it could be possible for the neutrinos to switch between types.

    By 1975, part of Pontecorvo’s theory had been proven correct. Three different types, or “flavors,” of neutrino had been discovered: electron neutrinos, muon neutrinos, and tau neutrinos. Importantly, observations from an experiment in a South Dakota mineshaft had confirmed that the Sun produced electron neutrinos. The only issue was that the experiment detected far fewer neutrinos than the Standard Model predicted.

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA


    FNAL DUNE Argon tank at SURF


    Surf-Dune/LBNF Caverns at Sanford



    SURF building in Lead SD USA

    Prior to the late 90s, there was scant indirect evidence that neutrinos could change from one flavor to another. In 1998, a group of researchers working in Japan’s Super-Kamiokande Observatory observed oscillations in atmospheric neutrinos, which are mostly produced by the interactions between photons and the Earth’s atmosphere.

    Super-Kamiokande experiment. located under Mount Ikeno near the city of Hida, Gifu Prefecture, Japan

    Three years later, Canada’s Sudbury Neutrino Observatory (SNO) provided the first direct evidence of oscillations from solar neutrinos.

    Sudbury Neutrino Observatory, no longer operating

    This was, to put it lightly, a big deal in cosmological physics. It effectively resolved the mystery of the missing solar neutrinos, or why experiments only observed about a third as many neutrinos radiating from the Sun compared to predictions made by the Standard Model. If neutrinos could oscillate between flavors, this means a neutrino that is emitted in the Sun’s core could be a different type of neutrino by the time it reaches Earth. Prior to the mid-80s, most experiments on Earth were only looking for electron neutrinos, which meant they were missing the other two flavors of neutrinos that were created en route from the Sun to the Earth.

    When SNO was dreamt up in the 80s, it was designed so that it would be capable of detecting all three types of neutrinos, instead of just electron neutrinos. This decision paid off. In 2015, the directors of the experiments at Super-Kamiokande and SNO shared the Nobel Prize in physics for resolving the mystery of the missing solar neutrinos.

    Although the mystery of solar neutrinos has been solved, there’s still plenty of science to be done to better understand them. Since 2007, Gran Sasso’s Borexino observatory has been refining the measurements of solar neutrino flux, which has given physicists unprecedented insight into the fusion process powering the Sun. From the outside, the Borexino observatory looks like a large metal sphere, but on the inside it looks like a technology transplanted from an alien world.

    Borexino detector. Image INFN

    In the center of the sphere is basically a large, transparent nylon sack that is almost 30 feet in diameter and only half a millimeter thick. This sack contains a liquid scintillator, a chemical mixture that releases energy when a neutrino passes through it. This nylon sphere is suspended in 1,000 metric tons of a purified buffer liquid and surrounded by 2,200 sensors to detect energy released by electrons that are freed when neutrinos interact with the liquid scintillator. Finally, an outer buffer of nearly 3,000 tons of ultrapure water helps provide additional shielding for the detector. Taken together, the Borexino observatory has the most protection from outside radiation interference of any liquid scintillator in the world.

    For the last decade, physicists at Borexino—including D’Angelo, who joined the project in 2011—have been using this one-of-a-kind device to observe low energy solar neutrinos produced by proton collisions during the fusion process in the Sun’s core. Given how difficult it is to detect these chargless, ultralight particles that hardly ever interact with matter, detecting the low energy solar neutrinos would be virtually impossible without such a sensitive machine. When SNO directly detected the first solar neutrino oscillations, for instance, it could only observe the highest energy solar neutrinos due to interference from background radiation. This amounted to only about 0.01 percent of all the neutrinos emitted by the Sun. Borexino’s sensitivity allows it to observe solar neutrinos whose energy is a full order of magnitude lower than those detected by SNO, opening the door for an incredibly refined model of solar processes as well as more exotic events like supernovae.

    “It took physicists 40 years to understand solar neutrinos and it’s been one of the most interesting puzzles in particle physics,” D’Angelo told me. “It’s kind of like how dark matter is now.”

    SHINING A LIGHT ON DARK MATTER

    If neutrinos were the mystery particle of the twentieth century, then dark matter is the particle conundrum for the new millenium. Just like Pauli proposed neutrinos as a “desperate remedy” to explain why experiments seemed to be violating one of the most fundamental laws of nature, the existence of dark matter particles is inferred because cosmological observations just don’t add up.

    In the early 1930s, the American astronomer Fritz Zwicky was studying the movement of a handful of galaxies in the Coma cluster, a collection of over 1,000 galaxies approximately 320 million light years from Earth.

    Fritz Zwicky, the Father of Dark Matter research.No image credit after long search

    Vera Rubin did much of the work on proving the existence of Dark Matter. She and Fritz were both overlooked for the Nobel prize.

    Vera Rubin measuring spectra (Emilio Segre Visual Archives AIP SPL)


    Astronomer Vera Rubin at the Lowell Observatory in 1965. (The Carnegie Institution for Science)

    Using data published by Edwin Hubble, Zwicky calculated the mass of the entire Coma galaxy cluster.

    Coma cluster via NASA/ESA Hubble

    When he did, Zwicky noticed something odd about the velocity dispersion—the statistical distribribution of the speeds of a group of objects—of the galaxies: The velocity distribution was about 12 times higher than it should be based on the amount of matter in the galaxies.

    Inside Gran Sasso- Image- Xavier Aaronson-Motherboard

    This was a surprising calculation and its significance wasn’t lost on Zwicky. “If this would be confirmed,” he wrote, “we would get the surprising result that dark matter is present in much greater amount than luminous matter.”

    The idea that the universe was made up mostly of invisible matter was a radical idea in Zwicky’s time and still is today. The main difference, however, is that astronomers now have much stronger empirical evidence pointing to its existence. This is mostly due to the American astronomer Vera Rubin, whose measurement of galactic rotations in the 1960s and 70s put the existence of dark matter beyond a doubt. In fact, based on Rubin’s measurements and subsequent observations, physicists now think dark matter makes up about 27 percent of the “stuff” in the universe, about seven times more than the regular, baryonic matter we’re all familiar with. The burning question, then, is what is it made of?

    Since Rubin’s pioneering observations, a number of dark matter candidate particles have been proposed, but so far all of them have eluded detection by some of the world’s most sensitive instruments. Part of the reason for this is that physicists aren’t exactly sure what they’re looking for. In fact, a small minority of physicists think dark matter might not be a particle at all and is just an exotic gravitational effect. This makes designing dark matter experiments kind of like finding a car key in a stadium parking lot and trying to track down the vehicle it pairs with. There’s a pretty good chance the car is somewhere in the parking lot, but you’re going to have to try a lot of doors before you find your ride—if it even exists.

    Among the candidates for dark matter are subatomic particles with goofy names like axions, gravitinos, Massive Astrophysical Compact Halo Objects (MACHOs), and Weakly Interacting Massive Particles (WMIPs.) D’Angelo and his colleagues at Gran Sasso have placed their bets on WIMPs, which until recently were considered to be the leading particle candidate for dark matter.

    Over the last few years, however, physicists have started to look at other possibilities after some critical tests failed to confirm the existence of WIMPs. WIMPs are a class of hypothetical elementary particles that hardly ever interact with regular baryonic matter and don’t emit light, which makes them exceedingly hard to detect. This problem is compounded by the fact that no one is really sure how to characterize a WIMP. Needless to say, it’s hard to find something if you’re not even really sure what you’re looking for.

    So why would physicists think WIMPs exist at all? In the 1970s, physicists conceptualized the Standard Model of particle physics, which posited that everything in the universe was made out of a handful of fundamental particles.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.


    Standard Model of Particle Physics from Symmetry Magazine

    The Standard Model works great at explaining almost everything the universe throws at it, but it’s still incomplete since it doesn’t incorporate gravity into the model.

    Gravity measured with two slightly different torsion pendulum set ups and slightly different results

    In the 1980s, an extension of the Standard Model called Supersymmetry emerged, which hypothesizes that each fundamental particle in the Standard Model has a partner.

    Standard model of Supersymmetry DESY

    These particle pairs are known as supersymmetric particles and are used as the theoretical explanation for a number of mysteries in Standard Model physics, such as the mass of the Higgs boson and the existence of dark matter. Some of the most complex and expensive experiments in the world like the Large Hadron Collider particle accelerator were created in an effort to discover these supersymmetric particles, but so far there’s been no experimental evidence that these particles actually exist.

    LHC

    CERN map


    CERN LHC Tunnel

    CERN LHC particles

    Many of the lightest particles theorized in the supersymmetric model are WIMPs and go by names like the gravitino, sneutrino and neutralino. The latter is still considered to be the leading candidate for dark matter by many physicists and is thought to have formed in abundance in the early universe. Detecting evidence of this ancient theoretical particle is the goal of many dark matter experiments, including the one D’Angelo works on at Gran Sasso.

    D’Angelo told me he became interested in dark matter a few years after joining the Gran Sasso laboratory and began contributing to the laboratory’s DarkSide experiment, which seemed like a natural extension of his work on solar neutrinos. DarkSide is essentially a large tank filled with liquid argon and equipped with incredibly sensitive sensors. If WIMPs exist, physicists expect to detect them from the ionization produced through their collision with the argon nuclei.

    Dark Side-50 Dark Matter Experiment at Gran Sasso

    The set up of the SABRE experiment is deliberately similar to another experiment that has been running at Gran Sasso since 1995 called DAMA. In 2003, the DAMA experiment began looking for seasonal fluctuations in dark matter particles that was predicted in the 1980s as a consequence of the relative motion of the sun and Earth to the rest of the galaxy. The theory posited that the relative speed of any dark matter particles detected on Earth should peak in June and bottom out in December.

    The DarkSide experiment has been running at Gran Sasso since 2013 and D’Angelo said it is expected to continue for several more years. These days, however, he’s found himself involved with a different dark matter experiment at Gran Sasso called SABRE [above], which will also look for direct evidence of dark matter particles based on the light produced when energy is released through their collision with Sodium-Iodide crystals.

    Over the course of nearly 15 years, DAMA did in fact register seasonal fluctuations in its detectors that were in accordance with this theory and the expected signature of a dark matter particle. In short, it seemed as if DAMA was the first experiment in the world to detect a dark matter particle. The problem, however, was that DAMA couldn’t completely rule out the possibility that the signature it had detected was in fact due to some other seasonal variation on Earth, rather than the ebb and flow of dark matter as the Earth revolved around the Sun.

    SABRE aims to remove the ambiguities in DAMA’s data. After all the kinks are worked out in the testing equipment, the Gran Sasso experiment will become one half of SABRE. The other half will be located in Australia in a converted gold mine. By having a laboratory in the northern hemisphere and another in the southern hemisphere, this should help eliminate any false positives that result from normal seasonal fluctuations. At the moment, the SABRE detector is still in a proof of principle phase and is expected to begin observations in both hemispheres within the next few years.

    When it comes to SABRE, it’s possible that the experiment may disprove the best evidence physicists have found so far for a dark matter particle. But as D’Angelo pointed out, this type of disappointment is a fundamental part of science.

    “Of course I am afraid that there might not be any dark matter there and we are hunting ghosts, but science is like this,” D’Angelo said. “Sometimes you spend several years looking for something and in the end it’s not there so you have to change the way you were thinking about things.”

    For D’Angelo, probing the subatomic world with neutrino and dark matter research from a cave in Italy is his way of connecting to the universe writ large.

    “The tiniest elements of nature are bonded to the most macroscopic phenomena, like the expansion of the universe,” D’Angelo said. “The infinitely small touches the infinitely big in this sense, and I find that fascinating. The physics I do, it’s goal is to push over the boundary of human knowledge.”

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Gran Sasso LABORATORI NAZIONALI del GRAN SASSO, located in the Abruzzo region of central Italy

    INFN Gran Sasso National Laboratory (LNGS) is the largest underground laboratory in the world devoted to neutrino and astroparticle physics, a worldwide research facility for scientists working in this field of research, where particle physics, cosmology and astrophysics meet. It is unequalled anywhere else, as it offers the most advanced underground infrastructures in terms of dimensions, complexity and completeness.

    LNGS is funded by the National Institute for Nuclear Physics (INFN), the Italian Institution in charge to coordinate and support research in elementary particles physics, nuclear and sub nuclear physics

    Located between L’Aquila and Teramo, at about 120 kilometres from Rome, the underground structures are on one side of the 10-kilometre long highway tunnel which crosses the Gran Sasso massif (towards Rome); the underground complex consists of three huge experimental halls (each 100-metre long, 20-metre large and 18-metre high) and bypass tunnels, for a total volume of about 180.000 m3.

    Access to experimental halls is horizontal and it is made easier by the highway tunnel. Halls are equipped with all technical and safety equipment and plants necessary for the experimental activities and to ensure proper working conditions for people involved.

    The 1400 metre-rock thickness above the Laboratory represents a natural coverage that provides a cosmic ray flux reduction by one million times; moreover, the flux of neutrons in the underground halls is about thousand times less than on the surface due to the very small amount of uranium and thorium of the Dolomite calcareous rock of the mountain.

    The permeability of cosmic radiation provided by the rock coverage together with the huge dimensions and the impressive basic infrastructure, make the Laboratory unmatched in the detection of weak or rare signals, which are relevant for astroparticle, sub nuclear and nuclear physics.

    Outside, immersed in a National Park of exceptional environmental and naturalistic interest on the slopes of the Gran Sasso mountain chain, an area of more than 23 acres hosts laboratories and workshops, the Computing Centre, the Directorate and several other Offices.

    Currently 1100 scientists from 29 different Countries are taking part in the experimental activities of LNGS.
    LNGS research activities range from neutrino physics to dark matter search, to nuclear astrophysics, and also to earth physics, biology and fundamental physics.

     
    • Marco Pereira 2:43 pm on September 1, 2018 Permalink | Reply

      I created a theory called the Hypergeometrical Universe Theory (HU). This theory uses three hypotheses:
      a) The Universe is a lightspeed expanding hyperspherical hypersurface. This was later proven correct by observations by the Sloan Digital Sky Survey
      https://hypergeometricaluniverse.quora.com/Proof-of-an-Extra-Spatial-Dimension
      b) Matter is made directly and simply from coherences between stationary states of deformation of the local metric called Fundamental Dilator or FD.
      https://hypergeometricaluniverse.quora.com/The-Fundamental-Dilator
      c) FDs obey the Quantum Lagrangian Principle (QLP). Yves Couder had a physical implementation (approximation) of the Fundamental Dilator and was perplexed that it would behave Quantum Mechanically. FDs and the QLP are the reason for Quantum Mechanics. QLP replaces Newtonian Dynamics and allows for the derivation of Quantum Gravity or Gravity as applied to Black Holes.

      HU derives a new law of Gravitation that is epoch-dependent. That makes Type 1a Supernovae to be epoch-dependent (within the context of the theory). HU then derives the Absolute Luminosity of SN1a as a function of G and showed that Absolute Luminosity scales with G^{-3}.
      Once corrected the Photometrically Determined SN1a distances, HU CORRECTLY PREDICTS all SN1a distances given their redshifts z.

      The extra dimension refutes all 4D spacetime theories, including General Relativity and L-CDM. HU also falsifies all Dark Matter evidence:
      https://www.quora.com/Are-dark-matter-and-dark-energy-falsifiable/answer/Marco-Pereira-1
      including the Spiral Galaxy Conundrum and the Coma Cluster Conundrum.

      Somehow, my theory is still been censored by the community as a whole (either directly or by omission).

      I hope this posting will help correct this situation.

      Like

  • richardmitnick 4:04 pm on July 12, 2018 Permalink | Reply
    Tags: , , , , , , Super-Kamiokande Collaboration   

    From Ethan Siegel: “How A Failed Nuclear Experiment Accidentally Gave Birth To Neutrino Astronomy” 

    From Ethan Siegel
    Jul 10, 2018

    1
    A neutrino event, identifiable by the rings of Cerenkov radiation that show up along the photomultiplier tubes lining the detector walls, showcase the successful methodology of neutrino astronomy. This image shows multiple events. Super Kamiokande collaboration

    Sometimes, the best-designed experiments fail. The effect you’re looking for might not even occur, meaning that a null result should always be a possible outcome you’re prepared for. When that happens, the experiment is often dismissed as a failure, even though you never would have known the results without performing it.

    Yet, every once in a while, the apparatus that you build might be sensitive to something else entirely. When you do science in a new way, at a new sensitivity, or under new, unique conditions, that’s often where the most surprising, serendipitous discoveries are made. In 1987, a failed experiment for detecting proton decay detected neutrinos, for the first time, from beyond not only our Solar System, but from outside of the Milky Way. This is how neutrino astronomy was born.

    2
    The conversion of a neutron to a proton, an electron, and an anti-electron neutrino is how Pauli hypothesized resolving the energy non-conservation problem in beta decay. Joel Holdsworth

    The neutrino is one of the great success stories in all the history of theoretical physics. Back in the early 20th century, three types of radioactive decay were known:

    Alpha decay, where a larger atom emits a helium nucleus, jumping two elements down the periodic table.
    Beta decay, where an atomic nucleus emits a high-energy electron, moving one element up the periodic table.
    Gamma decay, where an atomic nucleus emits an energetic photon, remaining in the same location on the periodic table.

    In any reaction, under the laws of physics, whatever the total energy and momentum of the initial reactants are, the energy and momentum of the final products need to match. For alpha and gamma decays, they always did. But for beta decays? Never. Energy was always lost.

    3
    The V-shaped track in the center of the image is likely a muon decaying to an electron and two neutrinos. The high-energy track with a kink in it is evidence of a mid-air particle decay. This decay, if the (undetected) neutrino is not included, would violate energy conservation.The Scottish Science & Technology Roadshow

    In 1930, Wolfgang Pauli proposed a new particle that could solve the problem: the neutrino. This small, neutral particle could carry both energy and momentum, but would be extremely difficult to detect. It wouldn’t absorb or emit light, and would only interact with atomic nuclei extremely rarely.

    Upon its proposal, rather than confident and elated, Pauli felt ashamed. “I have done a terrible thing, I have postulated a particle that cannot be detected,” he declared. But despite his reservations, the theory was vindicated by experiment.

    4
    Reactor nuclear experimental RA-6 (Republica Argentina 6), en marcha, showing the characteristic Cherenkov radiation from the faster-than-light-in-water particles emitted. The neutrinos (or more accurately, antineutrinos) first hypothesized by Pauli in 1930 were detected from a similar nuclear reactor in 1956. Centro Atomico Bariloche, via Pieck Darío

    In 1956, neutrinos (or more specifically, antineutrinos) were first directly detected as part of the products of a nuclear reactor. When neutrinos interact with an atomic nucleus, two things can result:

    they either scatter and cause a recoil, like a billiard ball knocking into other billiard balls,
    or they cause the emission of new particles, which have their own energies and momenta.

    Either way, you can build specialized particle detectors around where you expect the neutrinos to interact, and look for them. This was how the first neutrinos were detected: by building particle detectors sensitive to neutrino signatures at the edges of nuclear reactors. If you reconstructed the entire energy of the products, including neutrinos, energy is conserved after all.

    5
    Schematic illustration of nuclear beta decay in a massive atomic nucleus. Only if the (missing) neutrino energy and momentum is included can these quantities be conserved. Wikimedia Commons user Inductiveload

    In theory, neutrinos should be produced wherever nuclear reactions take place: in the Sun, in stars and supernovae, and whenever an incoming high-energy cosmic ray strikes a particle from Earth’s atmosphere. By the 1960s, physicists were building neutrino detectors to look for both solar (from the Sun) and atmospheric (from cosmic ray) neutrinos.

    A large amount of material, with mass designed to interact with the neutrinos inside of it, would be surrounded by this neutrino detection technology. In order to shield the neutrino detectors from other particles, they were placed far underground: in mines. Only neutrinos should make it into the mines; the other particles should be absorbed by the Earth. By the end of the 1960s, solar and atmospheric neutrinos had both successfully been found.

    1
    The Homestake Gold Mine sits wedged in the mountains in Lead, South Dakota. It began operation over 123 years ago, producing 40 million ounces of gold from the 8,000 foot deep underground mine and mill. In 1968, the first Solar neutrinos were detected at an experiment here, devised by John Bahcall and Ray Davis. (Jean-Marc Giboux/Liaison)

    The particle detection technology that was developed for both neutrino experiments and high-energy accelerators was found to be applicable to another phenomenon: the search for proton decay. While the Standard Model of particle physics predicts that the proton is absolutely stable, in many extensions — such as Grand Unification Theories — the proton can decay into lighter particles.

    In theory, whenever a proton does decay, it will emit lower-mass particles at very high speeds. If you can detect the energies and momenta of those fast-moving particles, you can reconstruct what the total energy is, and see if it came from a proton.

    6
    High-energy particles can collide with others, producing showers of new particles that can be seen in a detector. By reconstructing the energy, momentum, and other properties of each one, we can determine what initially collided and what was produced in this event. Fermilab

    If protons decay, their lifetime must be extremely long. The Universe itself is 1010 years old, but the proton’s lifetime must be much longer. How much longer? The key is to look not at one proton, but at an enormous number. If a proton’s lifetime is 1030 years, you can either take a single proton and wait that long (a bad idea), or take 1030 protons and wait 1 year to see if any decay.

    A liter of water contains a little over 1025 molecules in it, where each molecule contains two hydrogen atoms: a proton orbited by an electron. If the proton is unstable, a large enough tank of water, with a large set of detectors around it, should allow you to either measure or constrain its stability/instability.

    7
    A schematic layout of the KamiokaNDE apparatus from the 1980s. For scale, the tank is approximately 15 meters (50 feet) tall.©Jnn / Wikimedia Commons

    In Japan, in 1982, they began constructing a large underground detector in the Kamioka mines. The detector was named KamiokaNDE: Kamioka Nucleon Decay Experiment.

    Super-Kamiokande Detector, located under Mount Ikeno near the city of Hida, Gifu Prefecture, Japan

    It was large enough to hold over 3,000 tons of water, with around a thousand detectors optimized to detect the radiation that fast-moving particles would emit.

    By 1987, the detector had been running for years, without a single instance of proton decay. With around 1033 protons in that tank, this null result completely eliminated the most popular model among Grand Unified Theories. The proton, as far as we could tell, doesn’t decay. KamiokaNDE’s main objective was a failure.

    9
    A supernova explosion enriches the surrounding interstellar medium with heavy elements. The outer rings are caused by previous ejecta, long before the final explosion. This explosion also emitted a huge variety of neutrinos, some of which made it all the way to Earth. ESO / L. Calçada

    But then something unexpected happened. 165,000 years earlier, in a satellite galaxy of the Milky Way, a massive star reached the end of its life and exploded in a supernova. On February 23, 1987, that light reached Earth for the first time.

    This is an artist’s impression of the SN 1987A remnant. The image is based on real data and reveals the cold, inner regions of the remnant, in red, where tremendous amounts of dust were detected and imaged by ALMA. This inner region is contrasted with the outer shell, lacy white and blue circles, where the blast wave from the supernova is colliding with the envelope of gas ejected from the star prior to its powerful detonation. Image credit: ALMA / ESO / NAOJ / NRAO / Alexandra Angelich, NRAO / AUI / NSF.

    But a few hours before that light arrived, something remarkable happened at KamiokaNDE: a total of 12 neutrinos arrived within a span of about 13 seconds. Two bursts — the first containing 9 neutrinos and the second containing 3 — demonstrated that the nuclear processes that create neutrinos occur in great abundance in supernovae.

    10
    Three different detectors observed the neutrinos from SN 1987A, with KamiokaNDE the most robust and successful. The transformation from a nucleon decay experiment to a neutrino detector experiment would pave the way for the developing science of neutrino astronomy.Institute for Nuclear Theory / University of Washington

    For the first time, we had detected neutrinos from beyond our Solar System. The science of neutrino astronomy had just begun. Over the next few days, the light from that supernova, now known as SN 1987A, was observed in a huge variety of wavelengths by a number of ground-based and space-based observatories. Based on the tiny difference in the time-of-flight of the neutrinos and the arrival time of the light, we learned that neutrinos:

    traveled that 165,000 light years at a speed indistinguishable from the speed of light,
    that their mass could be no more than 1/30,000th the mass of an electron,
    and that neutrinos aren’t slowed down as they travel from the core of the collapsing star to its photospher, the way that light is.

    Even today, more than 30 years later, we can examine this supernova remnant and see how it’s evolved.

    11
    The outward-moving shockwave of material from the 1987 explosion continues to collide with previous ejecta from the formerly massive star, heating and illuminating the material when collisions occur. A wide variety of observatories continue to image the supernova remnant today.NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation) and P. Challis (Harvard-Smithsonian Center for Astrophysics)

    The scientific importance of this result cannot be overstated. It marked the birth of neutrino astronomy, just as the first direct detection of gravitational waves from merging black holes marked the birth of gravitational wave astronomy. It was the birth of multi-messenger astronomy, marking the first time that the same object had been observed in both electromagnetic radiation (light) and via another method (neutrinos).

    It showed us the potential of using large, underground tanks to detect cosmic events. And it causes us to hope that, someday, we might make the ultimate observation: an event where light, neutrinos, and gravitational waves all come together to teach us all about the workings of the objects in our Universe.

    13
    The ultimate event for multi-messenger astronomy would be a merger of either two white dwarfs or two neutrons stars that was close enough. If such an event occurred in near-enough proximity to Earth, neutrinos, light, and gravitational waves could all be detected.NASA, ESA, and A. Feild (STScI)

    The ultimate event for multi-messenger astronomy would be a merger of either two white dwarfs or two neutrons stars that was close enough. If such an event occurred in near-enough proximity to Earth, neutrinos, light, and gravitational waves could all be detected.NASA, ESA, and A. Feild (STScI)

    See the full article here .


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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 5:13 pm on August 23, 2016 Permalink | Reply
    Tags: , , , Hyper-Kamiokande, , , Super-Kamiokande Collaboration,   

    From Physics Today: “Six reasons to get excited about neutrinos” 

    Physics Today bloc

    Physics Today

    23 August 2016
    Andrew Grant

    Extra Dimensions: New results and upcoming experiments offer hope that neutrinos hold the key to expanding the standard model.

    The headlines from the recent International Conference on High Energy Physics (ICHEP) in Chicago trended sad, focused on the dearth of discoveries from the Large Hadron Collider. (See, for example, “Prospective particle disappears in new LHC data.”) Yet there was some optimism to be found in the Windy City, particularly among neutrino physicists. Here are six reasons to believe that neutrinos might provide the window into new physics that the LHC has not:

    Neutrinos are proof that the standard model is wrong. Sure, we know that dark matter and dark energy are missing from the standard model. But neutrinos are standard-model members, and the theoretical predictions are wrong. Prevailing theory says that neutrinos are massless; the Nobel-winning experiments at the Sudbury Neutrino Observatory and Super-Kamiokande demonstrated definitively that neutrinos oscillate between three flavors (electron, muon, and tau) and thus have mass. André de Gouvêa, a theoretical physicist at Northwestern University, deems neutrinos the “only palpable evidence of physics beyond the standard model.” Everything we learn about neutrinos in the coming years is new physics.

    1
    This signal from May 2014 denotes the detection of an electron neutrino by Fermilab’s NOvA experiment. Credit: NOvA Neutrino Experiment.

    FNAL/NOvA experiment
    FNAL/NOvA experiment map

    Neutrinos’ ability to morph from one flavor to another is only now starting to be understood. Each of neutrinos’ three flavors is actually a quantum superposition of three different mass states. By understanding the interplay of the three mass states, characterized by parameters called mixing angles, physicists can pin down how neutrinos transform between flavors. Fresh data from the NOvA experiment at Fermilab near Chicago suggest that neutrino mixing may not be as simple as most theories predict.

    Neutrinos may exhibit charge conjugation–parity (CP) violation. All known examples of CP violation, in which particle decays proceed differently with matter than with antimatter, take place in processes involving quark-containing particles like kaons and B mesons. But at the Neutrino 2016 meeting in London and at ICHEP, the T2K experiment offered fresh data hinting at matter–antimatter asymmetry for neutrinos.

    T2K Experiment
    Super-Kamiokande
    T2K map
    T2K Experiment

    After firing beams of muon neutrinos and antineutrinos at the Super-Kamiokande detector in Japan, scientists expected to detect 23 electron neutrinos and 7 electron antineutrinos; instead they have spotted 32 and 4, respectively. T2K isn’t anywhere close to achieving a 5 σ result, but the evidence for CP violation seems to be growing as the experiment acquires more data.

    Neutrinos may be the first fundamental particles that are Majorana fermions. Because the neutrino is the only fermion that is electrically neutral, it is also the only one that could be a Majorana fermion, a particle that is identical to its antiparticle. Learning whether neutrinos are Majorana particles or typical Dirac fermions would provide invaluable insight as to how neutrinos acquired mass at the dawn of the universe, de Gouvêa says. To determine the nature of neutrinos, physicists are hunting for a process called neutrinoless double beta decay. In typical double beta decay, two neutrons transform into protons and emit a pair of antineutrinos. If those antineutrinos are Majorana particles, they could annihilate each other. A 16 August paper from the KamLAND-Zen experiment in Japan reports the most stringent limits for the rate of neutrinoless double beta decay, further constraining the possibility that neutrinos are Majorana particles.

    Another neutrino flavor may be waiting to be discovered. The discovery of a fourth neutrino flavor, the sterile neutrino, would make every particle physicist forget about the LHC’s particle drought. Such a neutrino could enable physicists to explain dark matter or the absence of antimatter in the universe. The Antarctic detector IceCube just reported a negative result in the hunt for a sterile neutrino, but results from prior experiments still leave some wiggle room for the particle’s existence.

    Multiple powerful neutrino experiments are on the horizon. The NOvA experiment is up and running and delivering data that, at least so far, seem to complement T2K’s hints of CP violation. Fermilab scientists are already excited about the Deep Underground Neutrino Experiment, which should come on line around 2025.

    FNAL LBNF/DUNE from FNAL to SURF
    FNAL LBNF/DUNE from FNAL to SURF

    Hyper-Kamiokande, a megadetector in Japan with a million-ton tank of water for neutrino detection, should start operations around the same time.

    See the full article here .

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    “Our mission

    The mission of Physics Today is to be a unifying influence for the diverse areas of physics and the physics-related sciences.

    It does that in three ways:

    • by providing authoritative, engaging coverage of physical science research and its applications without regard to disciplinary boundaries;
    • by providing authoritative, engaging coverage of the often complex interactions of the physical sciences with each other and with other spheres of human endeavor; and
    • by providing a forum for the exchange of ideas within the scientific community.”

     
  • richardmitnick 1:25 pm on July 23, 2015 Permalink | Reply
    Tags: , , Super-Kamiokande Collaboration,   

    From Symmetry: “A new first for T2K” 

    Symmetry

    July 23, 2015
    Kathryn Jepsen

    1
    Courtesy of Kamioka Observatory, ICRR (Institute for Cosmic Ray Research), The University of Tokyo

    The Japan-based neutrino experiment has seen its first three candidate electron antineutrinos

    Scientists on the T2K neutrino experiment in Japan announced today that they have spotted their first possible electron antineutrinos.

    When the T2K experiment first began taking data in January 2010, it studied a beam of neutrinos traveling 295 kilometers from the J-PARC facility in Tokai, on the east coast, to the Super-Kamiokande detector in Kamioka in western Japan. Neutrinos rarely interact with matter, so they can stream straight through the earth from source to detector.

    From May 2014 to June 2015, scientists used a different beamline configuration to produce predominantly the antimatter partners of neutrinos, antineutrinos. After scientists eliminated signals that could have come from other particles, three candidate electron antineutrino events remained.

    T2K scientists hope to determine if there is a difference in the behavior of neutrinos and antineutrinos.

    “That is the holy grail of neutrino physics,” says Chang Kee Jung of State University of New York at Stony Brook, who until recently served as international co-spokesperson for the experiment.

    If scientists caught neutrinos and their antiparticles acting differently, it could help explain how matter came to dominate over antimatter after the big bang. The big bang should have produced equal amounts of each, which would have annihilated one another completely, leaving nothing to form our universe. And yet, here we are; scientists are looking for a way to explain that.

    “In the current paradigm of particle physics, this is the best bet,” Jung says.

    Scientists have previously seen differences in the ways that other matter and antimatter particles behave, but the differences have never been enough to explain our universe. Whether neutrinos and antineutrinos act differently is still an open question.

    Neutrinos come in three types: electron neutrinos, muon neutrinos and tau neutrinos. As they travel, they morph from one type to another. T2K scientists want to know if there’s a difference between the oscillations of muon neutrinos and muon antineutrinos. A possible upgrade to the Super-Kamiokande detector could help with future data-taking.

    One other currently operating experiment can look for this matter-antimatter difference: the [FNAL] NOvA experiment, which studies a beam that originates at Fermilab near Chicago with a detector near the Canadian border in Minnesota.

    FNAL NOvA experiment
    FNAL NOvA

    “This result shows the principle of the experiment is going to work,” says Indiana University physicist Mark Messier, co-spokesperson for the NOvA experiment. “With more data, we will be on the path to answering the big questions.”

    It might take T2K and NOvA data combined to get scientists closer to the answer, Jung says, and it will likely take until the construction of the even larger DUNE neutrino experiment in South Dakota to get a final verdict.

    See the full article here.

    Please help promote STEM in your local schools.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 11:54 am on July 22, 2015 Permalink | Reply
    Tags: , , Super-Kamiokande Collaboration,   

    From Symmetry: “Underground plans” 

    Symmetry

    July 22, 2015
    Liz Kruesi

    1
    Courtesy of Kamioka Observatory, ICRR (Institute for Cosmic Ray Research), The University of Tokyo

    The Super-Kamiokande collaboration has approved a project to improve the sensitivity of the Super-K neutrino detector.

    Super-Kamiokande, buried under about 1 kilometer of mountain rock in Kamioka, Japan, is one of the largest neutrino detectors on Earth. Its tank is full of 50,000 tons (about 13 million gallons) of ultrapure water, which it uses to search for signs of notoriously difficult-to-catch particles.

    Recently members of the Super-K collaboration gave the go-ahead to a plan to make the detector a thousand times more sensitive with the help of a chemical compound called gadolinium sulfate.

    Neutrinos are made in a variety of natural processes. They are also produced in nuclear reactors, and scientists can create beams of neutrinos in particle accelerators. These particles are electrically neutral, have little mass and interact only weakly with matter—characteristics that make them extremely difficult to detect even though trillions fly through any given detector each second.

    Super-K catches about 30 neutrinos that interact with the hydrogen and oxygen in the water molecules in its tank each day. It keeps its water ultrapure with a filtration system that removes bacteria, ions and gases.

    Scientists take extra precautions both to keep the ultrapure water clean and to avoid contact with the highly corrosive substance.

    “Somebody once dropped a hammer into the tank,” says experimentalist Mark Vagins of the University of Tokyo’s Kavli Institute for the Physics and Mathematics of the Universe. “It was chrome-plated to look nice and shiny. Eventually we found the chrome and not the hammer.”

    When a neutrino interacts in the Super-K detector, it creates other particles that travel through the water faster than the speed of light, creating a blue flash. The tank is lined with about 13,000 phototube detectors that can see the light.

    Looking for relic neutrinos

    On average, several massive stars explode as supernovae every second somewhere in the universe. If theory is correct, all supernovae to have exploded throughout the universe’s 13.8 billion years have thrown out trillions upon trillions of neutrinos. That means the cosmos would glow in a faint background of relic neutrinos—if scientists could just find a way to see even a fraction of those ghostlike particles.

    For about half of the year, the Super-K detector is used in the T2K experiment, which produces a beam of neutrinos in Tokai, Japan, some 183 miles (295 kilometers) away, and aims it at Super-K. During the trip to the detector, some of the neutrinos change from one type of neutrino to another. T2K studies that change, which could give scientists hints as to why our universe holds so much more matter than antimatter.

    But a T2K beam doesn’t run continuously during that half year. Instead, researchers send a beam pulse every few seconds, and each pulse lasts just a few microseconds long. Super-K still detects neutrinos from natural processes while scientists are running T2K.

    In 2002, at a neutrino meeting in Munich, Germany, experimentalist Vagins and theorist John Beacom of The Ohio State University began thinking of how they could better use Super-K to spy the universe’s relic supernova neutrinos.

    “For at least a few hours we were standing there in the Munich subway station somewhere deep underground, hatching our underground plans,” Beacom says.

    To pick out the few signals that come from neutrino events, you have to battle a constant clatter of background noise of other particles. Other incoming cosmic particles such as muons (the electron’s heavier cousin) or even electrons emitted from naturally occurring radioactive substances in rock can produce signals that look like the ones scientists hope to find from neutrinos. No one wants to claim a discovery that later turns out to be a signal from a nearby rock.

    Super-K already guards against some of this background noise by being buried underground. But some unwanted particles can get through, and so scientists need ways to separate the signals they want from deceiving background signals.

    Vagins and Beacom settled on an idea—and a name for the next stage of the experiment: Gadolinium Antineutrino Detector Zealously Outperforming Old Kamiokande, Super! (GADZOOKS!). They proposed to add 100 tons of the compound gadolinium sulfate—Gd2(SO4)3—to Super-K’s ultrapure water.

    When a neutrino interacts with a molecule, it releases a charged lepton (a muon, electron, tau or one of their antiparticles) along with a neutron. Neutrons are thousands of times more likely to interact with the gadolinium sulfate than with another water molecule. So when a neutrino traverses Super-K and interacts with a molecule, its muon, electron, or antiparticle (Super-K can’t see tau particles) will generate a first pulse of light, and the neutron will create a second pulse of light: “two pulses, like a knock-knock,” Beacom says.

    By contrast, a background muon or electron will make only one light pulse.

    To extract only the neutrino interactions, scientists will use GADZOOKS! to focus on the two-signal events and throw out the single-signal events, reducing the background noise considerably.

    The prototype

    But you can’t just add 100 tons of a chemical compound to a huge detector without doing some tests first. So Vagins and colleagues built a scaled-down version, which they called Evaluating Gadolinium’s Action on Detector Systems (EGADS). At 0.4 percent the size of Super-K, it uses 240 of the same phototubes and 200 tons (52,000 gallons) of ultrapure water.

    Over the past several years, Vagins’ team has worked extensively to show the benefits of their idea. One aspect of their efforts has been to build a filtration system that removes everything from the ultrapure water except for the gadolinium sulfate. They presented their results at a collaboration meeting in late June.

    On June 27, the Super-K team officially approved the proposal to add gadolinium sulfate but renamed the project SuperK-Gd. The next steps are to drain Super-K to check for leaks and fix them, replace any burned out phototubes, and then refill the tank.

    But this process must be coordinated with T2K, says Masayuki Nakahata, the Super-K collaboration spokesperson.

    Once the tank is refilled with ultrapure water, scientists will add in the 100 tons of gadolinium sulfate. Once the compound is added, the current filtration system could remove it any time researchers would like, Vagins says.

    “But I believe that once we get this into Super-K and we see the power of it, it’s going to become indispensable,” he says. “It’s going to be the kind of thing that people wouldn’t want to give up the extra physics once they’re used to it.”

    See the full article here.

    Please help promote STEM in your local schools.

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    Symmetry is a joint Fermilab/SLAC publication.


     
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