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  • richardmitnick 10:24 am on October 11, 2018 Permalink | Reply
    Tags: Antimatter, , , , , , , , , , ,   

    From Don Lincoln via CNN: “The ultimate mystery of the universe” 

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    From CNN

    September 21, 2018

    FNAL’s Don Lincoln

    This might win an award for “most obvious statement ever,” but the universe is big. And with its size comes big questions. Perhaps the biggest is “What makes the universe, well…the universe?”
    Researchers have made a crucial step forward in their effort to build scientific equipment that will help us answer that fundamental question.

    An international group of physicists collaborating on the Deep Underground Neutrino Experiment (DUNE) have announced that a prototype version of their equipment, called ProtoDUNE, is now operational.
    ProtoDUNE will validate the technology of the much larger DUNE experiment, which is designed to detect neutrinos, subatomic particles most often created in violent nuclear reactions like those that occur in nuclear power plants or the Sun. While they are prodigiously produced, they can pass, ghost-like, through ordinary matter. There are three distinct types of neutrinos, as different as the strawberry, vanilla, and chocolate flavors of Neapolitan ice cream.

    Further, through the always-confusing rules of quantum mechanics, these three types of neutrinos experience a startling behavior — they literally change their identity. Following the ice cream analogy, this would be like starting to eat a scoop of vanilla and, a few spoonfuls in, it magically changes to chocolate. It is through this morphing behavior that scientists hope to explain why our universe looks the way it does, rather than like a featureless void, full of energy and nothing else.

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    View of the interior of the ProtoDUNE experiment

    CERN Proto DUNE Maximillian Brice

    Large enough to encompass a three-story house, ProtoDUNE is located at the CERN laboratory, just outside Geneva, Switzerland. Years in the making, ProtoDUNE is filled with 800 tons of chilled liquid argon, which detects the passage of subatomic particles like neutrinos. Neutrinos hit the nuclei of the argon atoms in the ProtoDUNE detector, causing particles with electrical charge to be produced. Those particles then move through the detector, banging into argon atoms and knocking their electrons off. Scientists then detect the electrons.
    It’s similar to how you can know an airplane recently passed overhead because you observe contrails, the white streaks in the sky it briefly leaves behind. The ProtoDUNE detector has now observed particles coming from space — what scientists call cosmic rays — which has validated the effectiveness of the particle detector.

    Though considerably large, ProtoDUNE pales in comparison to the size of the DUNE apparatus, which is still being developed. DUNE will be based at two locations: Fermi National Accelerator Laboratory (Fermilab), which is America’s flagship particle physics laboratory located just outside Chicago, and the Sanford Underground Research Facility (SURF), located in Lead, South Dakota.

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

    Surf-Dune/LBNF Caverns at Sanford

    The biggest part of the DUNE experiment will ultimately consist of four large modules, each of which will be twenty times larger than ProtoDUNE. Because neutrinos interact very rarely with ordinary matter, bigger is better. And with an eighty times increase in volume, the DUNE detector will be able to detect eighty times as many neutrinos as ProtoDUNE.
    These large modules will be located nearly a mile underground at SURF. That depth is required to protect them from the same cosmic rays seen by ProtoDUNE.
    Fermilab will use its highest energy particle accelerator to generate a beam of neutrinos, which it will then shoot through the Earth to the waiting detectors over 800 miles away in western South Dakota.

    This beam of neutrinos will pass through a ProtoDUNE-like detector located at Fermilab to establish their characteristics as they leave the site. When the neutrinos arrive in South Dakota, the much bigger detectors again measure the neutrinos and look to see how much they have changed their identity as they traveled. It’s this identity-changing behavior that DUNE is designed to study. Scientists call this phenomenon “neutrino oscillations” because the neutrinos change from one type to another and then back again, over and over.
    While investigating and characterizing neutrino oscillations is the direct goal of the DUNE experiment, the deeper goal is to use those studies to shed light on one of those fundamental questions of the universe. This will be made possible because the DUNE experiment not only will study the oscillation behavior of neutrinos, it can also study the oscillation of antimatter neutrinos.

    A strong runner-up in the “most obvious statement ever” award is “our universe is made of matter.” But researchers have long known of a cousin substance called “antimatter.”

    Antimatter is the opposite of ordinary matter and will annihilate into pure energy when combined with matter. Alternatively, energy can simultaneously convert into matter and antimatter in equal quantities. This has been established beyond any credible doubt.

    Yet, with that observation, comes a mystery. Scientists generally accept that the universe came into existence through an event called the Big Bang. According to this theory, the universe was once much smaller, hotter, and full of energy. As the universe expanded, that energy should have converted into matter and antimatter in exactly equal quantities, which leads us to a very vexing question.

    Where the heck is the antimatter?

    Our universe consists only of matter, which means that something made the antimatter of the early universe disappear. Had this not happened, the matter and antimatter would have annihilated, and the universe would consist of nothing more than a bath of energy, without matter — without us.

    Which brings us back to the DUNE experiment. Fermilab will make not only neutrino beams, it will also make antimatter neutrino beams. The exact mix of neutrino “flavors” leaving the Fermilab campus will be established by the closer detector, and then again when they arrive at SURF, so that the changes due to neutrino oscillation can be measured. Then the same process will be done with antimatter neutrinos. If the matter and antimatter neutrinos oscillate differently, that will likely be a huge clue toward answering the question of why the universe exists as it does.

    With the completion of the new ProtoDUNE technology that will be used in the DUNE detector, the race is on to build the full facility. The first of the detector modules is scheduled to begin operations in 2026.

    While Fermilab has long made substantial contributions to the CERN research program, the DUNE experiment marks the first time that CERN has invested in scientific infrastructure in the United States. DUNE is a product of a unified international effort.
    Modern science is truly staggering in its accomplishments. We can cure deadly diseases and we’ve put men on the moon. But perhaps the grandest accomplishment of all is our ability to innovate in our effort to study in detail some of the oldest and most mind-boggling questions of our universe. And, with the success of ProtoDUNE, we’re that much closer to finding the answers.

    See the full article here .

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  • richardmitnick 9:02 am on August 26, 2018 Permalink | Reply
    Tags: , Antimatter, , , , , , ,   

    From CERN via Science Alert: “Physicists Are Almost Able to Cool Antimatter. Here’s Why That’s a Big Deal” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    From CERN

    via

    Science Alert

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    (koto_feja/iStock)

    26 AUG 2018
    KRISTIN HOUSER

    Where is all the antimatter?

    We’re still figuring out what the heck antimatter even is, but scientists are already getting ready to fiddle with it.

    Physicists at the European Organization for Nuclear Research (CERN) are one step closer to cooling antimatter using lasers, a milestone that could help us crack its many mysteries.

    They published their research on Wednesday in the journal Nature.

    Antimatter is essentially the opposite of “normal” matter. While protons have a positive charge, their antimatter equivalents, antiprotons, have the same mass, but a negative charge.

    Electrons and their corresponding antiparticle, positrons, have the same mass — the only difference is that they have different charges (negative for electrons, positive for positrons).

    When a particle meets its antimatter equivalent, the two annihilate one another, canceling the other out.

    In theory, the Big Bang should have produced an equal amount of matter and antimatter, in which case, the two would have just annihilated one another.

    But that’s not what happened — the Universe seems to have way more matter than antimatter.

    Researchers have no idea why that is, and because antimatter is very difficult to study, they haven’t had much recourse for figuring it out.

    And that’s why CERN researchers are trying to cool antimatter off, so they can get a better look.

    Using a tool called the Antihydrogen Laser Physics Apparatus (ALPHA), the researchers combined antiprotons with positrons to form antihydrogen atoms.

    CERN ALPHA Antimatter Factory

    Then, they magnetically trapped hundreds of these atoms in a vacuum and zapped them with laser pulses. This caused the antihydrogen atoms to undergo something called the Lyman-alpha transition.

    “The Lyman-alpha transition is the most basic, important transition in regular hydrogen atoms, and to capture the same phenomenon in antihydrogen opens up a new era in antimatter science,” one of the researchers, Takamasa Momose, said in a university press release.

    According to Momose, this phase change is a critical first step toward cooling antihydrogen.

    Researchers have long used lasers to cool other atoms to make them easier to study. If we can do the same for antimatter atoms, we’ll be better able to study them.

    Scientists can take more accurate measurements, and they might even be able to solve another long-unsettled mystery: figuring out how antimatter interacts with gravity.

    For now, the team plans to continue working toward that goal of cooling antimatter. If they’re successful, they might be able to help unravel mysteries with answers critical to our understanding of the Universe.

    See the full article here.

     
  • richardmitnick 5:32 pm on August 22, 2018 Permalink | Reply
    Tags: , Antihydrogen atom, Antimatter, , , Finding any slight difference between the behaviour of antimatter and matter would rock the foundations of the Standard Model of particle physics and perhaps cast light on why the universe is made up , , Lyman-alpha electronic transition, ,   

    From CERN: “ALPHA experiment takes antimatter to a new level” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    From CERN

    22 Aug 2018
    Ana Lopes

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    Jeffrey Hangst, spokesperson for the ALPHA experiment, next to the experiment. (Image: Maximilien Brice, Julien Ordan/CERN)

    CERN ALPHA Antimatter Factory

    In a paper published today in the journal Nature, the ALPHA collaboration reports that it has literally taken antimatter to a new level. The researchers have observed the Lyman-alpha electronic transition in the antihydrogen atom, the antimatter counterpart of hydrogen, for the first time. The finding comes hot on the heels of recent measurements by the collaboration of another electronic transition, and demonstrates that ALPHA is quickly and steadily paving the way for precision experiments that could uncover as yet unseen differences between the behaviour of matter and antimatter.

    The Lyman-alpha (or 1S-2P) transition is one of several in the Lyman series of electronic transitions that were discovered in atomic hydrogen just over a century ago by physicist Theodore Lyman. The transition occurs when an electron jumps from the lowest-energy (1S) level to a higher-energy (2P) level and then falls back to the 1S level by emitting a photon at a wavelength of 121.6 nanometres.

    It is a special transition. In astronomy, it allows researchers to probe the state of the medium that lies between galaxies and test models of the cosmos. In antimatter studies, it could enable precision measurements of how antihydrogen responds to light and gravity. Finding any slight difference between the behaviour of antimatter and matter would rock the foundations of the Standard Model of particle physics and perhaps cast light on why the universe is made up almost entirely of matter, even though equal amounts of antimatter should have been produced in the Big Bang.

    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 ALPHA team makes antihydrogen atoms by taking antiprotons from CERN’s Antiproton Decelerator (AD) and binding them with positrons from a sodium-22 source. It then confines the resulting antihydrogen atoms in a magnetic trap, which prevents them from coming into contact with matter and annihilating. Laser light is then shone onto the trapped atoms to measure their spectral response. The measurement involves using a range of laser frequencies and counting the number of atoms that drop out of the trap as a result of interactions between the laser and the trapped atoms.

    The ALPHA collaboration has previously employed this technique to measure the so-called 1S-2S transition. Using the same approach and a series of laser wavelengths around 121.6 nanometres, ALPHA has now detected the Lyman-alpha transition in antihydrogen and measured its frequency with a precision of a few parts in a hundred million, obtaining good agreement with the equivalent transition in hydrogen.

    This precision is not as high as that achieved in hydrogen, but the finding represents a pivotal technological step towards using the Lyman-alpha transition to chill large samples of antihydrogen using a technique known as laser cooling. Such samples would allow researchers to bring the precision of this and other measurements of antihydrogen to a level at which any differences between the behaviour of antihydrogen and hydrogen might emerge.

    “We are really excited about this result,” says Jeffrey Hangst, spokesperson for the ALPHA experiment. “The Lyman-alpha transition is notoriously difficult to probe – even in ‘normal’ hydrogen. But by exploiting our ability to trap and hold large numbers of antihydrogen atoms for several hours, and using a pulsed source of Lyman-alpha laser light, we were able to observe this transition. Next up is laser cooling, which will be a game-changer for precision spectroscopy and gravitational measurements.”

    See the full article here.


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    Meet CERN in a variety of places:

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    THE FOUR MAJOR PROJECT COLLABORATIONS

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  • richardmitnick 11:58 pm on April 28, 2018 Permalink | Reply
    Tags: , Antiatoms sent to ALPHA - ASACUSA -BASE- AEGIS- GBARY[TUDY ANTIMAATER AND 'CREATE' ANTIATOMS, Antimatter, Antiproton Decelerator, , , CERN Antiproton Decelerator produces antiatoms, , , , Proton Synchrotron   

    From CERN: ” LIVE- Inside CERN’s antimatter factory” 

    Cern New Bloc

    Cern New Particle Event

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    CERN

    26 Apr 2018
    Harriet Kim Jarlett

    1
    This is the antimatter trap at AEgIS, one of the experiments studying antimatter using CERN’s Antiproton Decelerator (Image: Maximilien Brice and Julien Ordan/CERN)

    For the first time, join us on Facebook for a live behind-the-scenes insight into CERN’s Antiproton Decelerator.

    CERN Antiproton Decelerator

    The Antiproton Decelerator (AD) is a unique machine that produces low-energy antiprotons for studies of antimatter, and “creates” antiatoms. The Decelerator produces antiproton beams and sends them to the different experiments.

    A proton beam that comes from the PS (Proton Synchrotron) is fired into a block of metal. These collisions create a multitude of secondary particles, including lots of antiprotons. These antiprotons have too much energy to be useful for making antiatoms. They also have different energies and move randomly in all directions. The job of the AD is to tame these unruly particles and turn them into a useful, low-energy beam that can be used to produce antimatter.

    Unlike the rest of CERN’s accelerator complex, which speed up particles to study them at high energies, this unique machine slows particles down. The decelerator tames these unruly particles and directs them to six different experiments, ALPHA, ASACUSA, ATRAP, BASE, AEGIS and GBAR. to study antimatter and ‘create’ antiatoms.

    The Big Bang should have created equal amounts of matter and antimatter in the early universe. But today, everything we see from the smallest life forms on Earth to the largest stellar objects is made almost entirely of matter. Comparatively, there is not much antimatter to be found. Something must have happened to tip the balance. One of the greatest challenges in physics is to figure out what happened to the antimatter, or why we see an asymmetry between matter and antimatter.

    We’ll find out why CERN is now the only lab in the world producing antimatter, how we create these antimatter particles and what these experiments will teach us about our Universe.

    Watch the live on Facebook:

    See the full article here.

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    Meet CERN in a variety of places:

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    THE FOUR MAJOR PROJECT COLLABORATIONS

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  • richardmitnick 8:08 am on April 11, 2018 Permalink | Reply
    Tags: Antihydrogen physics, Antimatter, , , ,   

    From UC Berkeley: “An Improved Method for Antihydrogen Spectroscopy” Berkeley Physics 

    UC Berkeley

    UC Berkeley

    April 4, 2018

    1
    Professor Jonathan Wurtele, undergraduate students Helia Kamal, Nate Belmore, Carlos Sierra, Stefania Balasiu, Cheyenne Nelson, graduate student Celeste Carruth, and Professor Joel Fajans.No image credit

    Berkeley physicists Joel Fajans and Jonathan Wurtele, along with their students and postdocs, have spent over a decade working on antihydrogen physics as part of the ALPHA Collaboration. The quest for precision antihydrogen spectroscopy was realized in a new paper that just appeared in Nature (Characterization of the 1S–2S transition in antihydrogen, Ahmadi et al.)

    Much of the effort of the Berkeley group has been to invent and develop new plasma physics techniques for synthesizing antihydrogen.

    A recent paper in Physical Review Letters, part of the thesis work of Celeste Carruth, reports an improved method for controlling plasma density and temperature, which in turn enabled a factor-of-ten increase in trapping rates. These increased trapping rates enabled reduced statistical and systematic errors that previously limited ALPHA measurements.

    The future is very promising. Improvements to the infrastructure for antiproton generation at CERN will provide on-demand antiprotons after the upcoming two-year CERN accelerator shutdown.

    Further improvements in antihydrogen synthesis may result from very successful plasma cavity cooling experiments by graduate student Eric Hunter. The work, interesting in their own right as a study of coupled nonlinear oscillators, appeared in Physics of Plasmas (Low magnetic field cooling of lepton plasmas via cyclotron-cavity resonance, E. Hunter et al.)

    The research has benefited from nearly two-dozen undergraduate students who have spent a summer at CERN working on ALPHA and worked here on the related plasma physics.

    CERN ALPHA Antimatter Factory

    See the full article here .

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    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

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  • richardmitnick 2:10 pm on April 4, 2018 Permalink | Reply
    Tags: A new era of precision for antimatter research, , Antimatter, , , , , , ,   

    From CERN ALPHA: “A new era of precision for antimatter research” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN ALPHA

    4 Apr 2018
    Ana Lopes

    1
    ALPHA experiment (Image: Maximilien Brice/CERN)

    The ALPHA collaboration has reported the most precise direct measurement of antimatter ever made, revealing the spectral structure of the antihydrogen atom in unprecedented colour. The result, published today in Nature, is the culmination of three decades of research and development at CERN, and opens a completely new era of high-precision tests between matter and antimatter.

    The humble hydrogen atom, comprising a single electron orbiting a single proton, is a giant in fundamental physics, underpinning the modern atomic picture. Its spectrum is characterised by well-known spectral lines at certain wavelengths, corresponding to the emission of photons of a certain frequency or colour when electrons jump between different orbits. Measurements of the hydrogen spectrum agree with theoretical predictions at the level of a few parts in a quadrillion (1015) — a stunning achievement that antimatter researchers have long sought to match for antihydrogen.

    Comparing such measurements with those of antihydrogen atoms, which comprise an antiproton orbited by a positron, tests a fundamental symmetry called charge-parity-time (CPT) invariance. Finding any slight difference between the two would rock the foundations of the Standard Model of particle physics and perhaps shed light on why the universe is made up almost entirely of matter, even though equal amounts of antimatter should have been created in the Big Bang.

    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

    Until now, however, it has been all but impossible to produce and trap sufficient numbers of delicate antihydrogen atoms, and to acquire the necessary optical interrogation technology, to make serious antihydrogen spectroscopy possible.

    The ALPHA team makes antihydrogen atoms by taking antiprotons from CERN’s Antiproton Decelerator (AD) and binding them with positrons from a sodium-22 source.

    CERN Antiproton Decelerator

    Next it confines the resulting antihydrogen atoms in a magnetic trap, which prevents them from coming into contact with matter and annihilating. Laser light is then shone onto the trapped antihydrogen atoms, their response measured and finally compared with that of hydrogen.

    In 2016, the ALPHA team used this approach to measure the frequency of the electronic transition between the lowest-energy state and the first excited state (the so-called 1S to 2S transition) of antihydrogen with a precision of a couple of parts in ten billion, finding good agreement with the equivalent transition in hydrogen. The measurement involved using two laser frequencies — one matching the frequency of the 1S–2S transition in hydrogen and another “detuned” from it — and counting the number of atoms that dropped out of the trap as a result of interactions between the laser and the trapped atoms.

    The latest result from ALPHA takes antihydrogen spectroscopy to the next level, using not just one but several detuned laser frequencies, with slightly lower and higher frequencies than the 1S–2S transition frequency in hydrogen. This allowed the team to measure the spectral shape, or spread in colours, of the 1S–2S antihydrogen transition and get a more precise measurement of its frequency. The shape matches that expected for hydrogen extremely well, and ALPHA was able to determine the 1S–2S antihydrogen transition frequency to a precision of a couple of parts in a trillion—a factor of 100 better than the 2016 measurement.

    “The precision achieved in the latest study is the ultimate accomplishment for us,” explains Jeffrey Hangst, spokesperson for the ALPHA experiment. “We have been trying to achieve this precision for 30 years and have finally done it.”

    Although the precision still falls short of that for ordinary hydrogen, the rapid progress made by ALPHA suggests hydrogen-like precision in antihydrogen — and thus unprecedented tests of CPT symmetry — are now within reach. “This is real laser spectroscopy with antimatter, and the matter community will take notice,” adds Hangst. “We are realising the whole promise of CERN’s AD facility; it’s a paradigm change.”


    ALPHA spokesperson Jeffrey Hangst explains the new results. (Video: Jacques Fichet/CERN)

    See the full article here.

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    Meet CERN in a variety of places:

    Quantum Diaries
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    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
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    CMS
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    CERN LHCb New II

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  • richardmitnick 10:06 am on February 26, 2018 Permalink | Reply
    Tags: Antimatter, , ,   

    From ScienceNews: “The quest to identify the nature of the neutrino’s alter ego is heating up” 


    ScienceNews

    February 26, 2018
    Emily Conover

    Physicists are trying to see if the particle’s matter and antimatter versions are the same.

    1
    ANTIMATTER MYSTERY Physicists suspect that the neutrino may be its own antiparticle. Experiments such as GERDA (shown) are attempting to determine whether that hunch is correct by searching for a rare type of nuclear decay. K. Freund/GERDA collaboration

    Galaxies, stars, planets and life, all are formed from one essential substance: matter.

    But the abundance of matter is one of the biggest unsolved mysteries of physics. The Big Bang, 13.8 billion years ago, spawned equal amounts of matter and its bizarro twin, antimatter. Matter and antimatter partners annihilate when they meet, so an even-stephen universe would have ended up full of energy — and nothing else. Somehow, the balance tipped toward matter in the early universe.

    A beguiling subatomic particle called a neutrino may reveal how that happened. If neutrinos are their own antiparticles — meaning that the neutrino’s matter and antimatter versions are the same thing — the lightweight particle might point to an explanation for the universe’s glut of matter.

    So scientists are hustling to find evidence of a hypothetical kind of nuclear decay that can occur only if neutrinos and antineutrinos are one and the same. Four experiments have recently published results showing no hint of the process, known as neutrinoless double beta decay (SN: 7/6/02, p. 10). But another attempt, set to begin soon, may have a fighting chance of detecting this decay, if it occurs. Meanwhile, planning is under way for a new generation of experiments that will make even more sensitive measurements.

    “Right now, we’re standing on the brink of what potentially could be a really big discovery,” says Janet Conrad, a neutrino physicist at MIT not involved with the experiments.

    A league of its own

    Each matter particle has an antiparticle, a partner with the opposite electric charge. Electrons have positrons as partners; protons have antiprotons. But it’s unclear how this pattern applies to neutrinos, which have no electric charge.

    Rather than having distinct matter and antimatter varieties, neutrinos might be the lone example of a theorized class of particle dubbed a Majorana fermion (SN: 8/19/17, p. 8), which are their own antiparticles. “No other particle that we know of could have this property; the neutrino is the only one,” says neutrino physicist Jason Detwiler of the University of Washington in Seattle, who is a member of the KamLAND-Zen and Majorana Demonstrator neutrinoless double beta decay experiments.

    Neutrinoless double beta decay is a variation on standard beta decay, a relatively common radioactive process that occurs naturally on Earth. In beta decay, a neutron within an atom’s nucleus converts into a proton, releasing an electron and an antineutrino. The element thereby transforms into another one further along the periodic table.

    ______________________________________________________
    Beta decays

    The standard type of beta decay (left) occurs when a neutron in an atom’s nucleus converts into a proton and releases an electron (blue, e-) and an antineutrino (red). For certain species of atoms, two such decays can happen at once (middle). If the neutrino is its own antiparticle, those double beta decays could also occur without any emitted antineutrinos (right).

    2
    ______________________________________________________

    In certain isotopes of particular elements — species of atoms characterized by a given number of protons and neutrons — two beta decays can occur simultaneously, emitting two electrons and two antineutrinos. Although double beta decay is exceedingly rare, it has been detected. If the neutrino is its own antiparticle, a neutrino-free version of this decay might also occur: In a rarity atop a rarity, the antineutrino emitted in one of the two simultaneous beta decays might be reabsorbed by the other, resulting in no escaping antineutrinos.

    Such a process “creates asymmetry between matter and antimatter,” says physicist Giorgio Gratta of Stanford University, who works on the EXO-200 neutrinoless double beta decay experiment.

    SLAC EXO-200 Enriched Xenon Observatory near Carlsbad, New Mexico

    In typical beta decay, one matter particle emitted — the electron — balances out the antimatter particle — the antineutrino. But in neutrinoless double beta decay, two electrons are emitted with no corresponding antimatter particles. Early in the universe, other processes might also have behaved in a similarly asymmetric way.

    On the hunt

    To spot the unusual decay, scientists are building experiments filled with carefully selected isotopes of certain elements and monitoring the material for electrons of a particular energy, which would be released in the neutrinoless decay.

    If any experiment observes this process, “it would be a huge deal,” says particle physicist Yury Kolomensky of the University of California, Berkeley, a member of the CUORE neutrinoless double beta decay experiment. “It is a Nobel Prize‒level discovery.”

    CUORE experiment UC Berkeley, experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS), a search for neutrinoless double beta decay

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

    Unfortunately, the latest results won’t be garnering any Nobels. In a paper accepted in Physical Review Letters, the GERDA experiment spotted no signs of the decay. Located in the Gran Sasso underground lab in Italy, GERDA looks for the decay of the isotope germanium-76. (The number indicates the quantity of protons and neutrons in the atom’s nucleus.) Since there were no signs of the decay, if the process occurs it must be extremely rare, the scientists concluded, and its half-life must be long — more than 80 trillion trillion years.

    Three other experiments have also recently come up empty. The Majorana Demonstrator experiment, located at the Sanford Underground Research Facility in Lead, S.D., which also looks for the decay in germanium, reported no evidence of neutrinoless double beta decay in a paper accepted in Physical Review Letters.

    U Washington Majorana Demonstrator Experiment at SURF

    Meanwhile, EXO-200, located in the Waste Isolation Pilot Plant, underground in a salt deposit near Carlsbad, N.M., reported no signs of the decay in xenon-136 in a paper published in the Feb. 16 Physical Review Letters.

    Likewise, no evidence for the decay materialized in the CUORE experiment, in results reported in a paper accepted in Physical Review Letters. Composed of crystals containing tellurium-130, CUORE is also located in the Gran Sasso underground lab.

    The most sensitive search thus far comes from the KamLAND-Zen neutrinoless double beta decay experiment located in a mine in Hida, Japan, which found a half-life longer than 100 trillion trillion years for the neutrinoless double beta decay of xenon-136.


    KamLAND at the Kamioka Observatory in located in a mine in Hida, Japan

    That result means that, if neutrinos are their own antiparticles, their mass has to be less than about 0.061 to 0.165 electron volts depending on theoretical assumptions, the KamLAND-Zen collaboration reported in a 2016 paper in Physical Review Letters. (An electron volt is particle physicists’ unit of energy and mass. For comparison, an electron has a much larger mass of half a million electron volts.)

    Neutrinos, which come in three different varieties and have three different masses, are extremely light, but exactly how tiny those masses are is not known. Mass measured by neutrinoless double beta decay experiments is an effective mass, a kind of weighted average of the three neutrino masses. The smaller that mass, the lower the rate of the neutrinoless decays (and therefore the longer the half-life), and the harder the decays are to find.

    KamLAND-Zen looks for decays of xenon-136 dissolved in a tank of liquid. Now, KamLAND-Zen is embarking on a new incarnation of the experiment, using about twice as much xenon, which will reach down to even smaller masses, and even rarer decays. Finding neutrinoless double beta decay may be more likely below about 0.05 electron volts, where neutrino mass has been predicted to lie if the particles are their own antiparticles.

    Supersizing the search

    KamLAND-Zen’s new experiment is only a start. Decades of additional work may be necessary before scientists clinch the case for or against neutrinos being their own antiparticles. But, says KamLAND-Zen member Lindley Winslow, a physicist at MIT, “sometimes nature is very kind to you.” The experiment could begin taking data as early as this spring, says Winslow, who is also a member of CUORE.

    To keep searching, experiments must get bigger, while remaining extremely clean, free from any dust or contamination that could harbor radioactive isotopes. “What we are searching for is a decay that is very, very, very rare,” says GERDA collaborator Riccardo Brugnera, a physicist at the University of Padua in Italy. Anything that could mimic the decay could easily swamp the real thing, making the experiment less sensitive. Too many of those mimics, known as background, could limit the ability to see the decays, or to prove that they don’t occur.

    In a 2017 paper in Nature, the GERDA experiment deemed itself essentially free from background — a first among such experiments. Reaching that milestone is good news for the future of these experiments. Scientists from GERDA and the Majorana Demonstrator are preparing to team up on a bigger and better experiment, called LEGEND, and many other teams are also planning scaled-up versions of their current detectors.

    Antimatter whodunit

    If scientists conclude that neutrinos are their own antiparticles, that fact could reveal why antimatter is so scarce. It could also explain why neutrinos are vastly lighter than other particles. “You can kill multiple problems with one stone,” Conrad says.

    Theoretical physicists suggest that if neutrinos are their own antiparticles, undetected heavier neutrinos might be paired up with the lighter neutrinos that we observe. In what’s known as the seesaw mechanism, the bulky neutrino would act like a big kid on a seesaw, weighing down one end and lifting the lighter neutrinos to give them a smaller mass. At the same time, the heavy neutrinos — theorized to have existed at the high energies present in the young universe — could have given the infant cosmos its early preference for matter.

    Discovering that neutrinos are their own antiparticles wouldn’t clinch the seesaw scenario. But it would provide a strong hint that neutrinos are essential to explaining where the antimatter went. And that’s a question physicists would love to answer.

    “The biggest mystery in the universe is who stole all the antimatter. There’s no bigger theft that has occurred than that,” Conrad says.

    Citations

    J.B. Albert et al. Search for neutrinoless double-beta decay with the upgraded EXO-200 detector. Physical Review Letters. Vol. 120, February 16, 2018, p. 072701. doi: 10.1103/PhysRevLett.120.072701.

    C.E. Aalseth et al. Search for zero-neutrino double beta decay in 76Ge with the Majorana demonstrator. Physical Review Letters, in press, 2018.

    M. Agostini et al. Improved limit on neutrinoless double beta decay of 76Ge from GERDA Phase II. Physical Review Letters, in press, 2018.

    CUORE Collaboration. First results from CUORE: a search for lepton number violation via 0νββ decay of 130Te. Physical Review Letters, in press, 2018.

    KamLAND-Zen Collaboration. Search for majorana neutrinos near the inverted mass hierarchy region with KamLAND-Zen. Physical Review Letters. Vol. 117, August 19, 2017, p. 082503. doi:10.1103/PhysRevLett.117.082503.

    The GERDA Collaboration. Background-free search for neutrinoless double-β decay of 76Ge with GERDA. Nature. Vol. 544, April 6, 2017, p. 47. doi:10.1038/nature21717.

    See the full article here .

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  • richardmitnick 10:08 am on October 23, 2017 Permalink | Reply
    Tags: Antimatter, , , , , ,   

    From LBNL: “Experiment Provides Deeper Look into the Nature of Neutrinos” 

    Berkeley Logo

    Berkeley Lab

    October 23, 2017
    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 486-5582

    The first glimpse of data from the full array of a deeply chilled particle detector operating beneath a mountain in Italy sets the most precise limits yet on where scientists might find a theorized process to help explain why there is more matter than antimatter in the universe.

    This new result, submitted today to the journal Physical Review Letters, is based on two months of data collected from the full detector of the CUORE (Cryogenic Underground Observatory for Rare Events) experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) in Italy. CUORE means “heart” in Italian.

    The CUORE detector array, shown here in this rendering is formed by 19 copper-framed “towers” that each house a matrix of 52 cube-shaped crystals Credit CUORE collaboration

    CUORE experiment UC Berkeley, experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS), a search for neutrinoless double beta decay

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

    The Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) leads the U.S. nuclear physics effort for the international CUORE collaboration, which has about 150 members from 25 institutions. The U.S. nuclear physics program has made substantial contributions to the fabrication and scientific leadership of the CUORE detector.

    CUORE is considered one of the most promising efforts to determine whether tiny elementary particles called neutrinos, which interact only rarely with matter, are “Majorana particles” – identical to their own antiparticles. Most other particles are known to have antiparticles that have the same mass but a different charge, for example. CUORE could also help us home in on the exact masses of the three types, or “flavors,” of neutrinos – neutrinos have the unusual ability to morph into different forms.

    “This is the first preview of what an instrument this size is able to do,” said Oliviero Cremonesi, a senior faculty scientist at INFN and spokesperson for the CUORE collaboration. Already, the full detector array’s sensitivity has exceeded the precision of the measurements reported in April 2015 after a successful two-year test run that enlisted one detector tower. Over the next five years CUORE will collect about 100 times more data.

    Yury Kolomensky, a senior faculty scientist in the Nuclear Science Division at Lawrence Berkeley National Laboratory (Berkeley Lab) and U.S. spokesperson for the CUORE collaboration, said, “The detector is working exceptionally well and these two months of data are enough to exceed the previous limits.” Kolomensky is also a professor in the UC Berkeley Physics Department.

    The new data provide a narrow range in which scientists might expect to see any indication of the particle process it is designed to find, known as neutrinoless double beta decay.

    “CUORE is, in essence, one of the world’s most sensitive thermometers,” said Carlo Bucci, technical coordinator of the experiment and Italian spokesperson for the CUORE collaboration. Its detectors, formed by 19 copper-framed “towers” that each house a matrix of 52 cube-shaped, highly purified tellurium dioxide crystals, are suspended within the innermost chamber of six nested tanks.

    Cooled by the most powerful refrigerator of its kind, the tanks subject the detector to the coldest known temperature recorded in a cubic meter volume in the entire universe: minus 459 degrees Fahrenheit (10 milliKelvin).

    The detector array was designed and assembled over a 10-year period. It is shielded from many outside particles, such as cosmic rays that constantly bombard the Earth, by the 1,400 meters of rock above it, and by thick lead shielding that includes a radiation-depleted form of lead rescued from an ancient Roman shipwreck. Other detector materials were also prepared in ultrapure conditions, and the detectors were assembled in nitrogen-filled, sealed glove boxes to prevent contamination from regular air.

    “Designing, building, and operating CUORE has been a long journey and a fantastic achievement,” said Ettore Fiorini, an Italian physicist who developed the concept of CUORE’s heat-sensitive detectors (tellurium dioxide bolometers), and the spokesperson-emeritus of the CUORE collaboration. “Employing thermal detectors to study neutrinos took several decades and brought to the development of technologies that can now be applied in many fields of research.”

    Together weighing over 1,600 pounds, CUORE’s matrix of roughly fist-sized crystals is extremely sensitive to particle processes, especially at this extreme temperature. Associated instruments can precisely measure ever-slight temperature changes in the crystals resulting from these processes.

    Berkeley Lab and Lawrence Livermore National Laboratory scientists supplied roughly half of the crystals for the CUORE project. In addition, the Berkeley Lab team designed and fabricated the highly sensitive temperature sensors – called neutron transmutation doped thermistors – invented by Eugene Haller, a senior faculty scientist in Berkeley Lab’s Materials Sciences Division and a UC Berkeley faculty member.

    2
    CUORE was assembled in this specially designed clean room to help protect it from contaminants. (Credit: CUORE collaboration)

    Berkeley Lab researchers also designed and built a specialized clean room supplied with air depleted of natural radioactivity, so that the CUORE detectors could be installed into the cryostat in ultraclean conditions. And Berkeley Lab scientists and engineers, under the leadership of UC Berkeley postdoc Vivek Singh, worked with Italian colleagues to commission the CUORE cryogenic systems, including a uniquely powerful cooling system called a dilution refrigerator.

    Former UC Berkeley postdoctoral students Tom Banks and Tommy O’Donnell, who also had joint appointments in the Nuclear Science Division at Berkeley Lab, led the international team of physicists, engineers, and technicians to assemble over 10,000 parts into towers in nitrogen-filled glove boxes. They bonded almost 8,000 gold wires, measuring just 25 microns in diameter, to 100-micron sized pads on the temperature sensors, and on copper pads connected to detector wiring.

    CUORE measurements carry the telltale signature of specific types of particle interactions or particle decays – a spontaneous process by which a particle or particles transform into other particles.

    In double beta decay, which has been observed in previous experiments, two neutrons in the atomic nucleus of a radioactive element become two protons. Also, two electrons are emitted, along with two other particles called antineutrinos.

    Neutrinoless double beta decay, meanwhile – the specific process that CUORE is designed to find or to rule out – would not produce any antineutrinos. This would mean that neutrinos are their own antiparticles. During this decay process the two antineutrino particles would effectively wipe each other out, leaving no trace in the CUORE detector. Evidence for this type of decay process would also help scientists explain neutrinos’ role in the imbalance of matter vs. antimatter in our universe.

    Neutrinoless double beta decay is expected to be exceedingly rare, occurring at most (if at all) once every 100 septillion (1 followed by 26 zeros) years in a given atom’s nucleus. The large volume of detector crystals is intended to greatly increase the likelihood of recording such an event during the lifetime of the experiment.

    There is growing competition from new and planned experiments to resolve whether this process exists using a variety of search techniques, and Kolomensky noted, “The competition always helps. It drives progress, and also we can verify each other’s results, and help each other with materials screening and data analysis techniques.”

    Lindley Winslow of the Massachusetts Institute of Technology, who coordinated the analysis of the CUORE data, said, “We are tantalizingly close to completely unexplored territory and there is great possibility for discovery. It is an exciting time to be on the experiment.”

    CUORE is supported jointly by the Italian National Institute for Nuclear Physics Istituto Nazionale di Fisica Nucleare (INFN) in Italy, and the U.S. Department of Energy’s Office of Nuclear Physics, the National Science Foundation, and the Alfred P. Sloan Foundation in the U.S. The CORE collaboration includes about 150 scientists from Italy, U.S., China, France, and Spain, and is based in the underground Italian facility called INFN Gran Sasso National Laboratories (LNGS) of the INFN.

    CUORE collaboration members include: Italian National Institute for Nuclear Physics (INFN), University of Bologna, University of Genoa, University of Milano-Bicocca, and Sapienza University in Italy; California Polytechnic State University, San Luis Obispo; Berkeley Lab; Lawrence Livermore National Laboratory; Massachusetts Institute of Technology; University of California, Berkeley; University of California, Los Angeles; University of South Carolina; Virginia Polytechnic Institute and State University; and Yale University in the US; Saclay Nuclear Research Center (CEA) and the Center for Nuclear Science and Materials Science (CNRS/IN2P3) in France; and the Shanghai Institute of Applied Physics and Shanghai Jiao Tong University in China.

    The U.S.-CUORE team was lead by late Prof. Stuart Freedman until his untimely passing in 2012. Other current and former Berkeley Lab members of the CUORE collaboration not previously mentioned include US Contractor Project Manager Sergio Zimmermann (Engineering Division), former U.S. Contractor Project Manager Richard Kadel, staff scientists Jeffrey Beeman, Brian Fujikawa, Sarah Morgan, Alan Smith, postdocs Giovanni Benato, Raul Hennings-Yeomans, Ke Han, Yuan Mei, Bradford Welliver, Benjamin Schmidt, graduate students Adam Bryant, Alexey Drobizhev, Roger Huang, Laura Kogler, Jonathan Ouellet, and Sachi Wagaarachchi, and engineers David Biare, Luigi Cappelli, Lucio di Paolo, and Joseph Wallig.

    See the full article here .

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  • richardmitnick 2:33 pm on August 2, 2017 Permalink | Reply
    Tags: Antimatter, , , ,   

    From CERN: “The ALPHA experiment explores the secrets of antimatter” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    02 Aug 2017
    No writer credit

    1
    Alpha Experiment (Image: CERN)

    3 August 2017. In a paper published today in Nature, the ALPHA experiment at CERN’s Antiproton Decelerator reports the first observation of the hyperfine structure of antihydrogen, the antimatter counterpart of hydrogen. These findings point the way to ever more detailed analyses of the structure of antihydrogen and could help understand any differences between matter and antimatter.

    The researchers conducted spectroscopy measurements on homemade antihydrogen atoms, which drive transitions between different energy states of the anti-atoms. They could in this way improve previous measurements by identifying and measuring two spectral lines of antihydrogen. Spectroscopy is a way to probe the internal structure of atoms by studying their interaction with electromagnetic radiation.

    In 2012, the ALPHA experiment demonstrated for the first time the technical ability to measure the internal structure of atoms of antimatter. In 2016 [Nature], the team reported the first observation of an optical transition of antihydrogen. By exposing antihydrogen atoms to microwaves at a precise frequency, they have now induced hyperfine transitions and refined their measurements. The team were able to measure two spectral lines for antihydrogen, and observe no difference compared to the equivalent spectral lines for hydrogen, within experimental limits.

    “Spectroscopy is a very important tool in all areas of physics. We are now entering a new era as we extend spectroscopy to antimatter,” said Jeffrey Hangst, Spokesperson for the ALPHA experiment. “With our unique techniques, we are now able to observe the detailed structure of antimatter atoms in hours rather than weeks, something we could not even imagine a few years ago.”

    With their trapping techniques, ALPHA are now able to trap a significant number of antiatoms – up to 74 at a time – thereby facilitating precision measurements. With this new result, the ALPHA collaboration has clearly demonstrated the maturity of its techniques for probing the properties of antimatter atoms.

    The rapid progress of CERN’s experiments at the unique Antiproton Decelerator facility is very promising for ever more precise measurements to be carried out in the near future.

    See the full article here.

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    THE FOUR MAJOR PROJECT COLLABORATIONS

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  • richardmitnick 2:58 pm on April 11, 2017 Permalink | Reply
    Tags: Antimatter, , , ,   

    From Symmetry: “What’s left to learn about antimatter?” 

    Symmetry Mag

    Symmetry

    04/11/17
    Sarah Charley

    1
    BBC Focus Magazine

    What do shrimp, tennis balls and pulsars all have in common? They are all made from matter.

    Admittedly, that answer is a cop-out, but it highlights a big, persistent quandary for scientists: Why is everything made from matter when there is a perfectly good substitute—antimatter?

    The European laboratory CERN hosts several experiments to ascertain the properties of antimatter particles, which almost never survive in our matter-dominated world.

    Particles (such as the proton and electron) have oppositely charged antimatter doppelgangers (such as the antiproton and antielectron). Because they are opposite but equal, a matter particle and its antimatter partner annihilate when they meet.

    Antimatter wasn’t always rare. Theoretical and experimental research suggests that there was an equal amount of matter and antimatter right after the birth of our universe. But 13.8 billion years later, only matter-made structures remain in the visible universe.

    Scientists have found small differences between the behavior of matter and antimatter particles, but not enough to explain the imbalance that led antimatter to disappear while matter perseveres. Experiments at CERN are working to solve that riddle using three different strategies.

    3
    No image caption. No image credit. http://www.projectrho.com/public_html/rocket/antimatterfuel.php

    Antimatter under the microscope

    It’s well known that CERN is home to Large Hadron Collider, the world’s highest-energy particle accelerator. Less known is that CERN also hosts the world’s most powerful particle decelerator—a machine that slows down antiparticles to a near standstill.

    4
    Paving the way for a new antimatter experiment. The GBAR experiment will create antihydrogen ions at rest to study the action of gravity upon antimatter. 13 March 2017 | Author Iva Raynova | Tagged antimatter, ELENA, Antiproton Decelerator, gravity

    The antiproton decelerator is fed by CERN’s accelerator complex. A beam of energetic protons is diverted from CERN’s Proton Synchrotron and into a metal wall, spawning a multitude of new particles, including some antiprotons. The antiprotons are focused into a particle beam and slowed by electric fields inside the antiproton decelerator. From here they are fed into various antimatter experiments, which trap the antiprotons inside powerful magnetic fields.

    “All these experiments are trying to find differences between matter and antimatter that are not predicted by theory,” says Will Bertsche, a researcher at University of Manchester, who works in CERN’s antimatter factory. “We’re all trying to address the big question: Why is the universe made up of matter these days and not antimatter?”

    By cooling and trapping antimatter, scientists can intimately examine its properties without worrying that their particles will spontaneously encounter a matter companion and disappear. Some of the traps can preserve antiprotons for more than a year. Scientists can also combine antiprotons with positrons (antielectrons) to make antihydrogen.

    “Antihydrogen is fascinating because it lets us see how antimatter interacts with itself,” Bertsche says. “We’re getting a glimpse at how a mirror antimatter universe would behave.”

    Scientists in CERN’s antimatter factory have measured the mass, charge, light spectrum, and magnetic properties of antiprotons and antihydrogen to high precision. They also look at how antihydrogen atoms are affected by gravity; that is, do the anti-atoms fall up or down? One experiment is even trying to make an assortment of matter-antimatter hybrids, such as a helium atom in which one of the electrons is replaced with an orbiting antiproton.

    So far, all their measurements of trapped antimatter match the theory: Except for the opposite charge and spin, antimatter appears completely identical to matter. But these affirmative results don’t deter Bertsche from looking for antimatter surprises. There must be unpredicted disparities between these particle twins that can explain why matter won its battle with antimatter in the early universe.

    “There’s something missing in this model,” Bertsche says. “And nobody is sure what that is.”

    Antimatter in motion

    The LHCb experiment wants to answer this same question, but they are looking at antimatter particles that are not trapped.

    CERN/LHCb

    Instead, LHCb scientists study how free-range antimatter particles behave as they travel and transform inside the detector.

    “We’re recording how unstable matter and antimatter particles decay into showers of particles and the patterns they leave behind when they do,” says Sheldon Stone, a professor at Syracuse University working on the LHCb Experiment. “We can’t make these measurements if the particles aren’t moving.”

    The particles-in-motion experiments have already observed some small differences between matter and antimatter particles. In 1964 scientists at Brookhaven National Laboratory noticed that neutral kaons (a particle containing a strange and down quark) decay into matter and antimatter particles at slightly different rates, an observation that won them the Nobel Prize in 1980.

    7
    Brookhaven. Two spectrometer magnets. No image credit

    The LHCb experiment continues this legacy, looking for even more discrepancies between the metamorphoses of matter and antimatter particles. They recently observed that the daughter particles of certain antimatter baryons (particles containing three quarks) have a slightly different spatial orientation than their matter contemporaries.

    But even with the success of uncovering these discrepancies, scientists are still very far from understanding why antimatter all but disappeared.

    “Theory tells us that we’re still off by nine orders of magnitude,” Stone says, “so we’re left asking, where is it? What is antimatter’s Achilles heel that precipitated its disappearance?”

    Antimatter in space

    Most antimatter experiments based at CERN produce antiparticles by accelerating and colliding protons. But one experiment is looking for feral antimatter freely roaming through outer space.

    The Alpha Magnetic Spectrometer is an international experiment supported by the US Department of Energy and NASA.

    AMS 02 schematic

    This particle detector was assembled at CERN and is now installed on the International Space Station, where it orbits Earth 400 kilometers above the surface. It records the momentum and trajectory of roughly a billion vagabond particles every month, including a million antimatter particles.

    Nomadic antimatter nuclei could be lonely relics from the Big Bang or the rambling residue of nuclear fusion in antimatter stars.

    But AMS searches for phenomena not explained by our current models of the cosmos. One of its missions is to look for antimatter that is so complex and robust, there is no way it could have been produced through normal particle collisions in space.

    “Most scientists accept that antimatter disappeared from our universe because it is somehow less resilient than matter,” says Mike Capell, a researcher at MIT and a deputy spokesperson of the AMS experiment. “But we’re asking, what if all the antimatter never disappeared? What if it’s still out there?”

    If an antimatter kingdom exists, astronomers expect that they would observe mass particle-annihilation fizzing and shimmering at its boundary with our matter-dominated space—which they don’t. Not yet, at least. Because our universe is so immense (and still expanding), researchers on AMS hypothesize that maybe these intersections are too dim or distant for our telescopes.

    “We already have trouble seeing deep into our universe,” Capell says. “Because we’ve never seen a domain where matter meets antimatter, we don’t know what it would look like.”

    AMS has been collecting data for six years. From about 100 billion cosmic rays, they’ve identified a few strange events with characteristics of antihelium. Because the sample is so tiny, it’s impossible to say whether these anomalous events are the first messengers from an antimatter galaxy or simply part of the chaotic background.

    “It’s an exciting result,” Capell says. “However, we remain skeptical. We need data from many more cosmic rays before we can determine the identities of these anomalous particles.”

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
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