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  • richardmitnick 7:57 am on April 14, 2016 Permalink | Reply
    Tags: Accelerator Science, , , ,   

    From FNAL’s Don Lincoln on livescience: “Collider Unleashed! The LHC Will Soon Hit Its Stride” 

    Livescience

    April 12, 2016

    FNAL Don Lincoln
    Don Lincoln, Senior Scientist, Fermi National Accelerator Laboratory; Adjunct Professor of Physics, University of Notre Dame

    CERN/LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    If you’re a science groupie and would love nothing better than for a cornerstone scientific theory to be overthrown and replaced with something newer and better, then 2016 might well be your year. The world’s largest particle accelerator, the Large Hadron Collider (LHC), is resuming operations after a pause during the winter months, when the cost for electricity in France is highest.

    So why is it such a big deal that LHC coming back on line? It’s because this is the year the accelerator will operate at something approaching its design specifications. Scientists will smash the gas pedal to the floor, crank the fire hose wide open, spin the amplifier button to eleven or enact whatever metaphor you like. This year is the first real year of full-scale LHC operations.

    A particle smasher reborn

    Now if you actually are a science groupie, you know what the LHC is and have probably heard about some of its accomplishments. You know it smashes together two beams of protons traveling at nearly the speed of light. You know scientists using the LHC found the Higgs boson.

    CERN ATLAS Higgs Event
    CERN ATLAS Higgs Event

    CERN CMS Higgs Event
    CERN CMS Higgs Event

    You know that this marvel is the largest scientific device ever built.

    So what’s different now? Well, let’s go back in time to 2008, when the LHC circulated its first beams. At the time, the world’s premier particle accelerator was the U.S. Department of Energy’s Fermilab Tevatron, which collided beams at a whopping 2 trillion electron volts (TeV) of energy and with a beam brightness of about 2 × 1032 cm-2 s-1.

    FNAL/Tevatron map
    FNAL/Tevatron map

    FNAL/Tevatron CDF
    FNAL/Tevatron CDF detectorFNAL/DZero detector
    FNAL/DZero detector

    The technical term for beam brightness is “instantaneous luminosity,” and basically it’s a density. More precisely, when a beam passes through a target, the instantaneous luminosity (L) is the number of particles per second in a beam that pass a location (ΔNB/Δt) divided by the area of the beam (A), multiplied by the number of targets (NT), L = ΔNB/Δt × (1/A) × NT. (And the target can be another beam.)

    The simplest analogy that will help you understand this quantity is a light source and a magnifying glass. You can increase the “luminosity” of the light by turning up the brightness of the light source or by focusing the light more tightly. It is the same way with a beam. You can increase the instantaneous luminosity by increasing the number of beam or target particles, or by concentrating the beam into a smaller area.

    The LHC was built to replace the Tevatron and trounce that machine’s already-impressive performance numbers.

    [If our USA Congress was not filled with idiots, we would have built in Texas the Superconducting Super Collider and not lost this HEP race.]

    The new accelerator was designed to collide beams at a collision energy of 14 TeV and to have a beam brightness — instantaneous luminosity — of at least 100 × 1032 cm-2 s-1. So the beam energy was to be seven times higher, and the beam brightness would increase 50- to 100-fold.

    Sadly, in 2008, a design flaw was uncovered in the LHC when an electrical short caused severe damage, requiring two years to repair . Further, when the LHC actually did run, in 2010, it operated at half the design energy (7 TeV) and at a beam brightness basically the same as that of the Fermilab Tevatron. The lower energy was to give a large safety margin, as the design flaw had been only patched, not completely reengineered.

    The situation improved in 2011 when the beam brightness got as high as 30 × 1032 cm-2 s-1, although with the same beam energy. In 2012, the beam energy was raised to 8 TeV, and the beam brightness was higher still, peaking at about 65 × 1032 cm-2 s-1.

    The LHC was shut down during 2013 and 2014 to retrofit the accelerator to make it safe to run at closer to design specifications. The retrofits consisted mostly of additional industrial safety measures that allowed for better monitoring of the electrical currents in the LHC. This helps ensure there are no electrical shorts and that there is sufficient venting. The venting guarantees no catastrophic ruptures of the LHC magnets (which steer the beams) in the event that cryogenic liquids — helium and nitrogen — in the magnets warm up and turn into a gas. In 2015, the LHC resumed operations, this time at 13 TeV and with a beam brightness of 40 × 1032 cm-2 s-1.

    So what’s expected in 2016?

    The LHC will run at 13 TeV and with a beam brightness that is expected to approach 100 × 1032 cm-2 s-1 and possibly even slightly exceed that mark. Essentially, the LHC will be running at design specifications.

    In addition, there is a technical change in 2016. The protons in the LHC beams will be spread more uniformly around the ring, thus reducing the number of protons colliding simultaneously, resulting in better data that is easier to interpret.

    At a technical level, this is kind of interesting. A particle beam isn’t continuous like a laser beam or water coming out of a hose. Instead, the beam comes in a couple of thousand distinct “bunches.” A bunch looks a little bit like a stick of uncooked spaghetti, except it is about a foot long and much thinner — about 0.3 millimeters, most of the time. These bunches travel in the huge 16-mile-long (27 kilometers) circle that is the LHC, with each bunch separated from the other bunches by a distance that (until now) has been about 50 feet (15 meters).

    The technical change in 2016 is to take the same number of beam protons (roughly 3 × 1014 protons) and split them up into 2,808 bunches, each separated not by 50 feet, but by 25 feet (7.6 m). This doubles the number of bunches, but cuts the number of protons in each bunch in half. (Each bunch contains about 1011 protons.)

    Because the LHC has the same number of protons but separated into more bunches, that means when two bunches cross and collide in the center of the detector, there are fewer collisions per crossing. Since most collisions are boring and low-energy affairs, having a lot of them at the same time that an interesting collision occurs just clutters up the data.

    Ideally, you’d like to have only an interesting collision and no simultaneous boring ones. This change of bunch separation distance from 50 feet to 25 feet brings the data collection closer to ideal.

    Luminous beams

    Another crucial design element is the integrated beam. Beam brightness (instantaneous luminosity) is related to the number of proton collisions per second, while integrated beam (integrated luminosity) is related to the total number of collisions that occur as the two counter-rotating beams continually pass through the detector. Integrated luminosity is something that adds up over the days, months and years.

    The unit of integrated luminosity is a pb-1. This unit is a bit confusing, but not so bad. The “b” in “pb” stands for a barn (more on that in a moment). A barn is 10-24 cm2. A picobarn (pb) is 10-36 cm2. The term “barn” is a unit of area and comes from another particle physics term called a cross section, which is related to how likely it is that two particles will interact and generate a specific outcome. Two objects that have large effective area will interact easily, while objects with a small effective area will interact rarely.

    An object with an area of a barn is a square with a length of 10-12 cm. That’s about the size of the nucleus of a uranium atom.

    During World War II, physicists at Purdue University in Indiana were working with uranium and needed to mask their work for security reasons. So they invented the term “barn,” defining it as an area about the size of a uranium nucleus. Given how big this area is in the eyes of nuclear and particle physicists, the Purdue scientists were co-opting the phrase “as big as a barn.” In the luminosity world, with its units of (1/barn), small numbers mean more luminosity.

    This trend is evident in the integrated luminosity seen in the LHC each year as scientists improved their ability to operate the accelerator. The integrated luminosity in 2010 was 45 pb-1. In 2011 and 2012, it was 6,100 pb-1 and 23,300 pb-1, respectively. As time went on, the accelerator ran more reliably, resulting in far higher numbers of recorded collisions.

    Because the accelerator had been re-configured during the 2013 to 2014 shutdown, the luminosity was lower in 2015, coming in at 4,200 pb-1, although, of course, at the much higher beam energy. The 2016 projection could be as high as 35,000 pb-1. The predicted increase merely reflects the accelerator operators’ increased confidence in their ability to operate the facility.

    This means in 2016, we could actually record eight times as much data as we did in 2015. And it is expected that 2017 will bring even higher performance.

    Illuminating new science

    Let’s think about what these improvements mean. When LHC first collided beams, in 2010, the Higgs boson was still to be observed.

    Higgs Boson Event
    Higgs Boson Event

    On the other hand, the particle was already predicted, and there was good circumstantial evidence to expect that the Higgs would be discovered. And, without a doubt, it must be admitted that the discovery of the Higgs boson was an enormous scientific triumph.

    But confirming previously predicted particles, no matter how impressive, is not why the LHC was built.

    Scientists’ current theory of the particle world is called the Standard Model, and it was developed in the late 1960s, half a century ago.

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

    While it is an incredibly successful theory, it is known to have holes. Although it explains why particles have mass, it doesn’t explain why some particles have more mass than others. It doesn’t explain why there are so many fundamental particles, given that only a handful of them are needed to constitute the ordinary matter of atoms and puppies and pizzas. It doesn’t explain why the universe is composed solely of matter, when the theory predicts that matter and antimatter should exist in equal quantities. It doesn’t identify dark matter, which is five times more prevalent than ordinary matter and is necessary to explain why galaxies rotate in a stately manner and don’t rip themselves apart.

    When you get right down to it, there is a lot the Standard Model doesn’t explain. And while there are tons of ideas about new and improved theories that could replace it, ideas are cheap. The trick is to find out which idea is right.

    That’s where the LHC comes in. The LHC can explore what happens if we expose matter to more and more severe conditions. Using Einstein’s equation E = mc2, we can see how the high-collision energies only achievable in the LHC are converted into forms of matter never before seen. We can sift through the LHC data to find clues that point us in the right direction to hopefully figure out the next bigger and more effective theory. We can take another step toward our ultimate goal of finding a theory of everything.

    With the LHC now operating at essentially design spec, we can finally use the machine to do what we built it for: to explore new realms, to investigate phenomena never before seen and, stealing a line from my favorite television show, “to boldly go where no one has gone before.” We scientists are excited. We’re giddy. We’re pumped. In fact, there can be but one way to express how we view this upcoming year:

    See the full article here .

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  • richardmitnick 3:37 pm on April 8, 2016 Permalink | Reply
    Tags: Accelerator Science, , , , , , ,   

    From FNAL: “Heavy neutrinos: Leave no stone unturned” 

    FNAL II photo

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    April 8, 2016
    Bo Jayatilaka

    While the discovery of the Higgs boson at the LHC yielded considerable evidence that the Higgs mechanism is responsible for some particles having mass and others not, it does not help explain why massive particles have the specific masses they do. Over a decade prior to the discovery of the Higgs boson, experiments studying neutrinos produced by the sun and by particle accelerators made the astounding discovery that neutrinos have mass, albeit in incredibly tiny amounts. The question du jour about neutrino masses shifted immediately from “Do neutrinos have mass?” to “Why are neutrino masses what they are?”

    Physicists naturally attack this question from as many angles as possible. A significant focus of the scientific efforts of Fermilab center on studying neutrinos produced by the Fermilab accelerator complex in order to probe this question. An experiment like CMS, designed to measure highly interactive particles, can’t directly detect neutrinos at all and might seem to be left on the sidelines in this quest. However, a popular family of theories suggests that there is an additional family of neutrino linked to the garden-variety neutrinos we know of. This linking mechanism between the known neutrinos and their exotic cousins is known as a “seesaw mechanism,” as it forces one type to become massive when the others become lightweight. Searching for unknown but massive particles is exactly what the CMS detector was designed to do.

    CERN/CMS Detector
    CERN/CMS Detector

    The CMS experiment has searched for such heavy neutrinos, focusing on the case where the heavy neutrino is of the Majorana type, meaning that it is its own antiparticle. As Don Lincoln explains about one of the first such searches, the production and decay of a heavy Majorana neutrino results in the signature of two leptons (electrons or muons) of the same electric charge along with jets. A more recent search at CMS used the full 8-TeV data set and focused on events in which the same-charged leptons were muons.

    To ensure that no stone remains unturned in the search for heavy Majorana neutrinos, the analysis of 8-TeV data has been updated* to include events with like-charged electron pairs and like-charged pairings of an electron and a muon.-

    Unfortunately, as with the previous searches, no evidence of a heavy neutrino was seen. However, the inclusion of electron and electron-muon pair events allowed CMS physicists to place significantly more stringent limits on the possible masses of heavy Majorana neutrinos. With Run 2 of the LHC under way, you can expect searches for Majorana neutrinos to push into ever higher masses.

    *Search for heavy Majorana neutrinos in e+/- e+/- plus jets and e+/- mu+/- plus jets events in proton-proton collisions at sqrt(s) = 8 TeV
    CMS Collaboration

    See the full article here .

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    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 3:23 pm on April 7, 2016 Permalink | Reply
    Tags: Accelerator Science, , , , , , , , ,   

    From Symmetry: “Physicists build ultra-powerful accelerator magnet” 

    Symmetry Mag

    Symmetry

    04/07/16
    Sarah Charley

    Magnet built for LHC

    The next generation of cutting-edge accelerator magnets is no longer just an idea. Recent tests revealed that the United States and CERN have successfully co-created a prototype superconducting accelerator magnet that is much more powerful than those currently inside the Large Hadron Collider.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    CERN/LHC

    Engineers will incorporate more than 20 magnets similar to this model into the next iteration of the LHC, which will take the stage in 2026 and increase the LHC’s luminosity by a factor of ten. That translates into a ten-fold increase in the data rate.

    “Building this magnet prototype was truly an international effort,” says Lucio Rossi, the head of the High-Luminosity (HighLumi) LHC project at CERN. “Half the magnetic coils inside the prototype were produced at CERN, and half at laboratories in the United States.”

    During the original construction of the Large Hadron Collider, US Department of Energy national laboratories foresaw the future need for stronger LHC magnets and created the LHC Accelerator Research Program (LARP): an R&D program committed to developing new accelerator technology for future LHC upgrades.

    MQXF1 quadrupole 1.5-meter prototype magnet sits at Fermilab before testing.
    MQXF1 quadrupole 1.5-meter prototype magnet sits at Fermilab before testing. G. Ambrosio (US-LARP and Fermilab), P. Ferracin and E. Todesco (CERN TE-MSC)

    This 1.5-meter-long model, which is a fully functioning accelerator magnet, was developed by scientists and engineers at Fermilab [FNAL], Brookhaven National Laboratory [BNL], Lawrence Berkeley National Laboratory [LBL], and CERN.

    FNAL II photo
    FNAL

    BNL Logo (2)
    BNL

    LBL Big
    LBL

    CERN
    CERN

    The magnet recently underwent an intense testing program at Fermilab, which it passed in March with flying colors. It will now undergo a rigorous series of endurance and stress tests to simulate the arduous conditions inside a particle accelerator.

    This new type of magnet will replace about 5 percent of the LHC’s focusing and steering magnets when the accelerator is converted into the High-Luminosity LHC, a planned upgrade which will increase the number and density of protons packed inside the accelerator. The HL-LHC upgrade will enable scientists to collect data at a much faster rate.

    The LHC’s magnets are made by repeatedly winding a superconducting cable into long coils. These coils are then installed on all sides of the beam pipe and encased inside a superfluid helium cryogenic system. When cooled to 1.9 Kelvin, the coils can carry a huge amount of electrical current with zero electrical resistance. By modulating the amount of current running through the coils, engineers can manipulate the strength and quality of the resulting magnetic field and control the particles inside the accelerator.

    The magnets currently inside the LHC are made from niobium titanium, a superconductor that can operate inside a magnetic field of up to 10 teslas before losing its superconducting properties. This new magnet is made from niobium-three tin (Nb3Sn), a superconductor capable of carrying current through a magnetic field of up to 20 teslas.

    “We’re dealing with a new technology that can achieve far beyond what was possible when the LHC was first constructed,” says Giorgio Apollinari, Fermilab scientist and Director of US LARP. “This new magnet technology will make the HL-LHC project possible and empower physicists to think about future applications of this technology in the field of accelerators.”

    High-Luminosity LHC coil
    High-Luminosity LHC coil similar to those incorporated into the successful magnet prototype shows the collaboration between CERN and the LHC Accelerator Research Program, LARP.
    Photo by Reidar Hahn, Fermilab

    This technology is powerful and versatile—like upgrading from a moped to a motorcycle. But this new super material doesn’t come without its drawbacks.

    “Niobium-three tin is much more complicated to work with than niobium titanium,” says Peter Wanderer, head of the Superconducting Magnet Division at Brookhaven National Lab. “It doesn’t become a superconductor until it is baked at 650 degrees Celsius. This heat-treatment changes the material’s atomic structure and it becomes almost as brittle as ceramic.”

    Building a moose-sized magnet from a material more fragile than a teacup is not an easy endeavor. Scientists and engineers at the US national laboratories spent 10 years designing and perfecting a new and internationally reproducible process to wind, form, bake and stabilize the coils.

    “The LARP-CERN collaboration works closely on all aspects of the design, fabrication and testing of the magnets,” says Soren Prestemon of the Berkeley Center for Magnet Technology at Berkeley Lab. “The success is a testament to the seamless nature of the collaboration, the level of expertise of the teams involved, and the ownership shown by the participating laboratories.”

    This model is a huge success for the engineers and scientists involved. But it is only the first step toward building the next big supercollider.

    “This test showed that it is possible,” Apollinari says. “The next step is it to apply everything we’ve learned moving from this prototype into bigger and bigger magnets.”

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 1:05 pm on April 6, 2016 Permalink | Reply
    Tags: Accelerator Science, , , , , ,   

    From CERN: “LINAC4 ready to go up in energy” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    4.6.16
    Jennifer Toes

    1
    The DTL section of the LINAC4 (Image: CERN)

    The LINAC4 linear accelerator has recently achieved beam commissioning of 50MeV and is now almost ready for the next step of increasing the beam energy even further up to 100MeV. This project is part of the LHC Injectors Upgrade (LIU) required for the needs of the High Luminosity LHC (HL-LHC).

    LINAC4 aims to replace the ageing LINAC2 linear accelerator, going from the present 50 MeV proton beam injection into the Proton Synchrotron Booster (PSB), the first ring in the CERN accelerator chain, to a modern H- ion beam injection at 160 MeV, more the three times the Linac2 energy.

    “CERN is one of the few laboratories in the world that has not yet implemented H- injection” said Alessandra Lombardi, who is responsible for the beam commissioning of the LINAC4. Injecting H- at a higher energy results in a smaller emittance in the PSB.

    Following the successful commissioning of the three newly designed Drift Tube Linac (DTL) tanks in November 2015, the team began its preparations for the installation of two key accelerating sectors: the Cell Coupled Drift Tube Linac (CCDTL) and PI-Mode Structures (PIMS).

    Built in Russia by a collaboration of CERN with two Russian laboratories, VNIITF in Snezinsk and BINP in Novossibirsk, the CCDTL is the next structure to be conditioned and commissioned with beam in the LINAC4.

    “The CERN CCDTL is composed of 7 modules of 3 tanklets each and it brings the energy of the beam from 50 to 100MeV” said Lombardi.

    The main advantage of CCDTLs over standard DTLs is that their quadrupoles are external and therefore more accessible. The accessibility of these magnets makes the construction and alignment process much more straight forward.

    The PIMS was constructed as part of a CERN-Poland (NCBJ Swierk) collaboration with contributions from FZ Jülich (Germany). The PIMS was assembled and tuned at CERN will bring up the beam energy from 100MeV to its final goal of 160MeV. It is composed of 12 modules for a total length of about 25m.

    Currently, the installation and conditioning of all CCDTL tanks and of the first PIMS is being carried out before beam commissioning begins on April 11th 2016. The commissioning of the remaining PIMS tanks expected to follow in October will allow reaching the final beam energy.

    Scheduled to become operational by 2020, the LINAC4 is a crucial step towards the increase in the LHC luminosity that will allow CERN to remain at the pinnacle of high energy physics research.

    See the full article here.

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    Meet CERN in a variety of places:

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

    Quantum Diaries

     
  • richardmitnick 1:23 pm on April 4, 2016 Permalink | Reply
    Tags: Accelerator Science, , , ,   

    From FNAL: “Putting it all together: Fermilab assembles first cryomodule for LCLS-II” 

    FNAL II photo

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    April 4, 2016
    Leah Hesla

    1
    Members of the Fermilab Technical Division line up eight superconducting accelerator cavities to form a cavity string destined for SLAC National Accelerator Laboratory’s LCLS-II. Photo: Reidar Hahn

    In February, a Fermilab team came together to witness a moment they’d looked forward to for over a year. Crew members parted the plastic sheeting at one end of a cleanroom and rolled out on narrow tracks a long string of eight accelerating cavities. It was the first cavity string for LCLS-II, which will greatly increase the power and capacity of SLAC’s Linac Coherent Light Source.

    SLAC/LCLS II schematic
    SLAC/LCLS II schematic

    Accelerating cavities are structures that impart energy to a particle beam, and they’re the heart of the cryomodule — a major accelerator section — that Fermilab has designed and is building for LCLS-II.

    “It’s a big deal. The cavity string’s all bolted up — it’s beautiful,” said SLAC scientist Marc Ross, LCLS-II cryogenics systems manager. “It’s a concrete step toward LCLS-II’s realization.”

    SLAC’s LCLS-II is a powerful X-ray laser that will allow scientists to glimpse nature’s fundamental processes on an atomic level and ultrafast time scales. Today SLAC announced DOE approval of the start of construction for LCLS-II.

    Since the rollout, the Fermilab team has been outfitting the cavity string with cooling equipment, instrumentation and structural support to form the cryomodule. By summer, they will have completed their first one.

    “To me this is a major milestone because it shows that we can do it,” said Camille Ginsburg, the cryomodule team lead for the Fermilab LCLS-II effort. “It represents having tested all of those cavities successfully, finalized the design and put together all the assembly infrastructure that was required.”

    The cryomodule is destined for LCLS-II’s new superconducting linear accelerator. Electrons speeding down the accelerator will generate an almost continuous X-ray laser beam with pulses of up to a million times per second — thousands of times faster than the current LCLS puts out. To be superconducting, the cryomodule’s cavities, made of niobium, must operate at minus 456 degrees Fahrenheit.

    The linear accelerator backbone of LCLS-II comprises 37 cryomodules. Thomas Jefferson National Accelerator Facility in Virginia, another LCLS-II collaborating institution, will build 18 cryomodules of this type. Fermilab is building 17 of these cryomodules plus two that will operate at a higher frequency.

    2
    Andrew Penhollow of the Fermilab Technical Division tends to the LCLS-II prototype cavity string, which is seen here mounted to cooling infrastructure. Photo: Reidar Hahn

    The boost from a pulsed beam to a continuous one means that the new accelerator will require much more power to operate. And with great power comes the need for great efficiency.

    That’s why Fermilab scientists have, for the better part of a decade, been working on methods for building and treating cavities to be as efficient as they can be. By imparting maximum energy to the beam with minimal energy loss, efficient cavities help drive down the cost.

    Last year, the Fermilab team reported a world-record quality factor, an indicator of the cavity’s efficiency in minimizing thermal losses.

    “The performance of the individually tested cavities that were put into the string was far beyond anything that has been put into such a cryomodule before,” Ross said.

    Fermilab also designed the cryomodule’s instrumentation to be able to handle the high power and its plumbing system to carry away heat.

    “With continuous-wave operation, there’s a much higher heat load than there is with pulsed-beam acceleration, so everything has to be more robust,” said Fermilab’s Elvin Harms, who leads cryomodule testing for LCLS-II at Fermilab.

    Scientists and engineers specially designed the couplers that transfer the radio-frequency power to the cavities with thicker, high-conductivity plating, for example, to carry away the high heat load.

    The assembly process to this point has been painstaking, said Fermilab scientist Anna Grassellino, who is responsible for cavity preparation and testing for LCLS-II. And it promises to remain that way until the cryomodule is finally delivered to SLAC.

    “Everything that’s happening now with the cryomodule assembly — every step is critical,” Grassellino said. “How you handle the parts can affect performance.”

    Technicians who successfully assembled the first cavity string in the cleanroom spent two weeks carefully putting the components together. Following a protocol established at DESY in Germany and Saclay in France and borne out in tests at the Fermilab Accelerator Science and Technology facility, they moved in slow motion, since too-rapid movements would create particulates that could make their way into the cavity, degrading its operation in an accelerator.

    “These techniques that seem ancillary are actually quite sophisticated,” Grassellino said. “When the cavity string was finished, it was, ‘Phew! Now it’s sealed, now it rolls out.’”

    Crews are carefully installing shielding to protect the cavities from Earth’s magnetic field, which would ruin their performance; welding the cavity string to the plumbing for the super-cooled helium that will keep the cavities cold; and connecting everything structurally inside the vacuum vessel.

    Cryomodule tests will begin early this summer. Fermilab and Jefferson Lab plan to move the completed cryomodules to SLAC toward the end of 2016.

    “Congratulations to the entire cryomodule team here, at Jefferson Lab and at SLAC,” said Rich Stanek, Fermilab LCLS-II senior team leader. “We’re working hard to deliver cryomodules that meet or exceed specifications within the project cost and schedule.”

    LCLS-II, like its predecessor LCLS, will be a DOE Office of Science User Facility.

    See the full article here .

    Please help promote STEM in your local schools.

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    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 4:09 pm on April 3, 2016 Permalink | Reply
    Tags: Accelerator Science, ,   

    From ALICE at CERN: “ALICE data visualisation: How it works” 

    CERN New Masthead

    CERN ALICE Icon HUGE

    16 December 2015 [Just posted on ALICE Matters]
    Iva Raynova

    Lead Ions collision at ALICE
    Lead Ions collision at ALICE

    The process behind ALICE data visualisation is long and complex, just like every other process included in the Large Hadron Collider operation. We met with Jeremi Niedziela, one of the people behind the development of the Event Display system, and asked him to reveal the path from a collision inside ALICE to its appearance on our monitors.

    Hello, Jeremi, what is your involvement in the process of data visualisation?

    My aim is to make sure that the visualisation for ALICE works properly. It mainly concerns online visualisation. When we have collisions, when we gather data, we want to see the outcome immediately. This is the main part of my job, to make all systems work.

    Would you describe the whole process?

    Everything starts inside ALICE. When we have collisions, new particles are created, which go through the detector and interact with it. As a result electric signals are generated, giving information about the particles. These are transformed into numbers (they are digitized) and they form the raw data, which are then sent to our computing rooms. These are filled with hundreds of computers recording and processing the information.

    Inside one of the computing rooms there is a machine dedicated to perform online reconstruction. Let’s take for example the Time Projection Chamber (TPC), which is filled with a gas mixture. When a particle goes through the TPC, it ionises the gas in several points in space. But we don’t have a continuous line, instead we have many, many points of interaction. This is valid not only for the TPC, but for other detectors as well.

    From this information we have to extract physical quantities like the momentum, the mass, the charge and the energy of the particle. The reconstruction takes the raw data, which are simply numbers, corresponding to an electronic output, and translates it into the language of physics. A part of this process is to fit tracks representing particles’ trajectories to those points of interaction with the detectors’ material.

    1

    When the run starts, a process called Visualisation Manager receives a signal and starts the reconstruction. It begins gathering raw data and producing reconstructed events, which are sent to the Event Display, running on one of the big screens in the Run Control Centre. The Event Display draws the tracks, the geometry of the detector and the calorimeter towers. It also produces a screenshot for each event and uploads it to a website called ALICE Live.

    2
    ALICE Live image

    This way we can only observe the last collision. If we want to see an event which happened for example two days ago, we send a query to the Visualisation Manager where the last few thousands of collisions are kept in a dedicated storage.

    3

    Do you know who uses the Event Display the most?

    Yes, one year ago I made a survey to find out who uses it and for what purposes. First of all, physicists and detector experts benefit from it. For example, someone working for the Inner Tracking System (ITS) replied that they use it to check hits position on the Silicon Drift Detector (SDD) for geometry check. Others use it for browsing events to understand what situations can be met during the analysis.

    It could also be used to create images or videos for conferences or for the general public. It’s useful in the outreach activities as well. You can display events for physics, fun and education of students. Talking about outreach, CERN MediaLab has a project, which is called Total Event Display. It is meant to be a common visualisation environment for all the experiments. ALICE also takes part in it, so I developed the code, which is needed for it.

    Another interesting project we’re working on is the Magic Window. There is a window between the ALICE Run Control Centre and the entrance to the elevator.

    ALICE Run Control Center
    ALICE Run Control Center

    It will be turned into a magic window with the help of a polarisation filter and a projector. It will also be a touchscreen, so we could display an interactive presentation about ALICE with Total Event Display. That means that visitors could see and explore collisions happening in real time.

    The Event Display in the ALICE Run Control Centre is also a part of the Data Quality Monitoring. It serves not so much for the experts to understand the physics process, but for us to be able to see if everything is working properly. If we see that tracks are drawn incorrectly, or if we don’t see tracks at all, then we immediately know that something went wrong along the way and we need to fix it. Sometimes it reveals problems which one would not associate with visualisation, but as we need to reconstruct events on the fly, it is a great way to control the whole system.

    See the full article here .

    Please help promote STEM in your local schools.

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    Meet CERN in a variety of places:

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New
    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New

    LHC

    CERN LHC New
    CERN LHC Grand Tunnel

    LHC particles

    Quantum Diaries

     
  • richardmitnick 12:28 pm on April 1, 2016 Permalink | Reply
    Tags: Accelerator Science, , , KEK Belle II, , ,   

    From Symmetry: “Belle II and the matter of antimatter” 

    Symmetry Mag
    Symmetry

    04/01/16
    Matthew R. Francis

    DESY Belle II detector
    DESY Belle II detector

    Go inside the new detector looking for why we’re here.

    We live in a world full of matter: stars made of matter, planets made of matter, pizza made of matter. But why is there pizza made of matter rather than pizza made of antimatter or, indeed, no pizza at all?

    In the first split-second after the big bang, the universe made a smidgen more matter than antimatter. Instead of matter and antimatter annihilating one another and leaving an empty, cold universe, we ended up with a surplus of stuff. Now scientists need the most sensitive detectors and mountains of experimental data to understand where that imbalance comes from.

    Belle II is one of those detectors that will look for differences between matter and antimatter to explain why we’re here at all. Currently under construction, the 7.5-meter-long detector will be installed in the newly recommissioned SuperKEKB particle accelerator located in Tsukuba, Japan.

    SuperKEKB accelerator Japan
    SuperKEKB accelerator Japan

    SuperKEKB runs beams of electrons and positrons (the antimatter version of electrons) into each other at close to the speed of light, and Belle II—once it is fully operational in 2018—will analyze the detritus of the collisions.

    “All the experimental results to this point have been consistent with the so-called Standard Model of particle physics,” says Tom Browder, a physicist at the University of Hawaii and one of the spokespeople for the project.

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

    But while the Standard Model allows for some asymmetry, it doesn’t explain the matter-antimatter imbalance that exists. We need something more.

    Belle II will look for the signatures of new physics in the rare decays of bottom quarks, charm quarks and tau leptons. (Bottom quarks are also known as beauty quarks, which is the “B” in SuperKEKB; the name “Belle” itself refers to “beauty”). Bottom and charm quarks are massive compared with the up and down quarks that make up ordinary matter, while tau leptons are the much heavier cousins of electrons. All three particles are unstable, decaying into a variety of lower-mass particles. If Belle II researchers spot a difference in the decays of these particles and their antimatter counterparts, it could explain why we ended up in a cosmos full of matter.

    Finding the beauty is a beast

    When electrons and positrons collide at low energy, they annihilate and convert all of their mass into gamma rays. At very high speed, however, the extra energy produces pairs of matter and antimatter particles, all of which are more massive than the original electrons. SuperKEKB smashes electrons and positrons together with the right energy to make B-mesons, particles made of a bottom quark and an antimatter quark of another type, along with anti-B-mesons, made of a bottom anti-quark and a matter quark.

    These mesons change into other particles in complex ways as the bottom quarks and antiquarks decay. Belle II’s detectors will try to find decays that either aren’t allowed by the Standard Model or happen more or less often than expected. Any such deviations could be signs of new physics. The detector can also help physicists better understand particles made of four or five quarks (tetraquarks and pentaquarks) or stuck-together “molecules” of quarks.

    “The cleaner environment at Belle II might make it easier to study some of those states, and to try to understand what the internal quark structure is,” says James Fast of the Department of Energy’s Pacific Northwest National Laboratory, lead lab for the US contributions to the Belle II detector upgrade.

    SuperKEKB collides electrons and positrons, which aren’t made of anything smaller. This results in a clean collision. And because the energy going into each collision at SuperKEKB is well known, Belle II can study decays with invisible particles such as neutrinos by looking for the missing energy they carry away.

    “The cleanliness of data at SuperKEKB enables the majority of B[-meson] events to be recorded,” says Kay Kinoshita of the University of Cincinnati, who works on the software Belle II will use to analyze collisions.

    But Belle II isn’t the only detector searching for these rare bottom quark decays. An experiment at the LHC, LHCb, is also on the hunt.

    CERN LHC LHCb
    CERN LHC LHCb

    The LHC produces a wider variety of particles containing bottom quarks. That includes a type that decays into two muons, “which is a ‘golden’ mode for effects from supersymmetry and theories with multiple Higgs bosons,” says Harry Cliff, a physicist at the University of Cambridge who works on LHCb.

    Race to the bottom

    Belle II is the aptly named successor to the Belle experiment and is designed to handle as much as 50 times the number of collisions in the previous design. It’s a monumental effort involving hundreds of physicists and engineers from 23 nations in Asia, Europe and North America.

    “The amount of data that Belle II will collect can be comparable to data management challenges that are faced by the big LHC experiments [like CMS and ATLAS],” says Fast.

    CERN CMS Detector
    CERN CMS Detector

    CERN/ATLAS
    CERN/ATLAS

    Universities don’t have the resources to operate the computers needed to manage all the data coming from Belle II, so a national lab like PNNL is an ideal host. Similar data centers for Belle II will operate in Japan and Europe.

    At present, the SuperKEKB accelerator is successfully storing both electrons and positrons to prepare for the tests that will lead to new experiments. The Belle II assembly will be in place next year, followed by a commissioning process to make sure everything is working properly. In 2018, the full experiment will be operational and producing data to find exotic B-meson behavior.

    It may feel ironic to take years to recreate what the universe did in a split second, but such is the nature of particle physics. The process of smashing electrons and positrons together isn’t identical to the process that created the early cosmos either, but if there’s any new physics hiding in the decays of bottom quarks, this is the type of experiment that could find it. Which is, after all, the beauty of science.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 3:56 pm on March 29, 2016 Permalink | Reply
    Tags: Accelerator Science, , , , ,   

    From Ethan Siegel: “What it means if CERN discovers a new particle” 

    Starts with a bang
    Starts with a Bang

    3.29.16
    Ethan Siegel

    CERN/LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN
    CERN/ATLAS
    CERN ATLAS Higgs Event
    ATLAS
    CERN CMS Detector
    CERN CMS Higgs Event
    CMS
    CERN/ALICE Detector
    ALICE
    CERN/LHCb
    LHCb

    There’s been a small but significant excess observed [1.6 σ], and a new particle is one possible explanation. What will it mean?

    “I’m a fan of supersymmetry, largely because it seems to be the only route by which gravity can be brought into the scheme. It’s probably not even enough, but it’s a way forward to get gravity involved. If you have supersymmetry, then there are more of these particles. That would be my favourite outcome.” –Peter Higgs

    In the 1960s and 1970s, the finishing theoretical touches were being put on the Standard Model of elementary particle physics.

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

    Inside the world of the atom were subatomic, fundamental particles, including electrons, two types of quarks and the gluons. In addition, over time, a whole slew of other particles were discovered:

    a total of six types of quarks and their corresponding antiparticles (antiquarks), each coming in three colors (or anticolors),
    three charged leptons and three neutral, low-mass neutrinos, each with their own antiparticles,
    and the bosons: the photon (for the electromagnetic force), the eight gluons (for the strong nuclear force), the W+, W- and the Z (for the weak force), plus the Higgs boson.

    1
    Image credit: E. Siegel, from his book, Beyond The Galaxy.

    It took 50 years from the time this model was set into place for the entire set to be discovered. The culmination of the Standard model was the discovery of the Higgs boson: earlier this decade at the Large Hadron Collider at CERN. But in that time, there were a whole slew of other mysteries that came about, mysteries that — by their very nature — require the existence of new particles to explain the physics we observed. They include:

    dark matter, or the fact that some 80–85% of the mass of the Universe cannot be accounted for by the particles in the Standard Model.
    neutrino masses, which should have been zero, but instead are tiny (millions of times lighter than the electron) and non-zero, and require a new particle to explain their existence.
    the matter-antimatter asymmetry, which cannot be explained by the known particles and interactions alone, and require new physics — particles and interactions — to account for what our Universe gives us.

    3
    One possible set of new particles that could give rise to the matter-antimatter asymmetry. Image credit: E. Siegel, from his book, Beyond The Galaxy.

    Many different scenarios exist that could explain these phenomena through the existence of new particles, but a few of the more interesting ones include supersymmetry, extra dimensions and technicolor extensions. Why are these, among others, interesting? Because if they are correct, they should give rise to new fundamental particles, particle beyond the Standard Model, that the LHC might see!

    Standard model of Supersymmetry Illustration: CERN & IES de SAR
    Standard model of Supersymmetry Illustration: CERN & IES de SAR

    Supersymmetry, for instance, predicts the existence — in all its forms — of at least one (and in most models, four) additional, heavy, Higgs-like particles. The way to discover a particle like this is to calculate, at all energies, what the expected contributions are from all the known particles to various decay pathways (two photons, two charged leptons, a W+ and W- boson, etc.), and then make the observations and look for differences.

    If you find significant enough differences in the right places, you’ll discover a new particle. This is how, in the past, we’ve discovered particles like the Z, the top quark and the Higgs.

    4
    Image credit: the LEP collaboration and various sub-collaborations, 2005, via http://arxiv.org/abs/hep-ex/0509008. Precision Electroweak Measurements on the Z Resonance. Note that the Z-particle appears with a “width” in energy.

    In December, the ATLAS collaboration announced that it appeared they had seen a little bit of evidence — not enough to claim discovery, but enough that it looked like it might not just be noise — of a new particle around 750 GeV in energy, or about five times the mass of the Higgs boson. It was consistent, they said, with another spin-0 particle, meaning that it might be another Higgs! At the same time, the CMS collaboration saw something very similar, although it was consistent with a spin-2 particle.

    As of last week, both collaborations have now taken the full suite of data currently available, and have come together (although with independent results) to compare.

    5
    The new signal at 750 GeV, via both the CMS and ATLAS collaborations. Image credit: Pauline Gagnon, via http://www.quantumdiaries.org/2016/03/18/two-steps-closer-to-a-possible-discovery/.

    Before you go getting all excited, realize the following: this might turn out to be nothing! Sure, there’s something fishy going on in this 750 GeV energy range, but the statistics up there are very limited right now. There’s a very good reason that particle physicists don’t claim discoveries of new particles until a certain standard (5σ significance) is reached: the dustbin of history is littered with “discoveries” that turned out to be mere fluctuations in the data that went away with more and better data. That could be exactly what we’re looking at here.

    The beautiful part of this is that we won’t have to wait forever. The LHC restarts at its highest energies and highest luminosities (i.e., the greatest numbers of collisions-per-second) ever this May, and by time mid-summer rolls around, we should know whether this is a true particle or merely a fluctuation. If it is a new particle, we’ll have our first direct hint of what lies beyond the Standard Model, and a new era in physics will be ushered in. But if it turns out to be a fluctuation — and if you’re a betting person, you’d be smart to bet on the fluctuation answer — it’s back to the drawing board for model-builders. The secrets of nature may turn out to be more elusive than physicists have imagined thus far.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    “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 9:52 am on March 25, 2016 Permalink | Reply
    Tags: Accelerator Science, , , , ,   

    From LHC/ATLAS at CERN: “Spring awakening for the ATLAS experiment” 

    CERN ATLAS Higgs Event

    CERN/ATLAS
    ATLAS

    24th March 2016
    Katarina Anthony

    This morning the Large Hadron Collider (LHC) circulated the first proton-proton beams of 2016 around its 27 kilometre circumference. The beams were met with great enthusiasm in the ATLAS Control Centre as they passed through the ATLAS experiment.

    These beams mark the start of an exciting new period for ATLAS and other CERN experiments. Having seen tantalising but still inconclusive signals in 2015, ATLAS physicists around the world are eagerly awaiting new data to analyse.

    The start of a new run also means the conclusion of a maintenance period, known as the Year-End-Technical-Stop (YETS). This 3 month-long upkeep is vital for the health and well-being of the detectors, ensuring that ATLAS can function impeccably for the 9 straight months of operation that follow.

    1
    ATLAS uses “beam splash” events to provide simultaneous signals to large parts of the detector, and verify that the readout of different detectors elements are fully synchronized. (Image: ATLAS Experiment © 2016 CERN)

    “This is a normal period of maintenance that happens yearly,” says Michel Raymond, ATLAS Deputy Technical Coordinator. “At ATLAS we use this time to repair and consolidate the detectors first, but also all the infrastructure around that allows us to run the detector.”

    But before their work can begin, there is a lot preparation needed. Although located in an enormous 52,500 m3 cavern, the ATLAS experiment fills that space nearly to the brink. Whatever room is left over is devoted to the cabling and cooling infrastructure that keeps the experiment running. “You cannot just go in and start working on a detector element,” says Raymond. “We first need to move the shielding and cabling to get the experiment into a configuration where the requested detector is accessible.”

    Moving these elements is called “opening” the detector and can take at least 3 weeks. The ATLAS teams have to go slowly and carefully, as they are moving fragile equipment that can weigh anywhere between 100 to 1000 tonnes.

    Once the detector elements are accessible, the teams have only a few weeks to get to work before they need to start closing the detector back up. “Every hour in the cavern is precious,” says Raymond. “We prioritise in advance what operations are the most important, and which can wait for next maintenance period.

    2
    This display shows one of the ATLAS Experiment’s first splashes on 2016, with beam 1 at 10:26 a.m. on Friday 25th March 2016. (Image: ATLAS Experiment © 2016 CERN)

    During this YETS period, the main priority was the repair of ATLAS’ end-cap magnet bellows. These bellows protect the integrity of the vacuum surrounding ATLAS cooling elements, and are essential for keeping the magnet system cool. They were damaged during a previous maintenance period though continued to work adequately throughout 2015. The damage was successfully repaired during this recent shutdown.

    “After that, we took action on the detector elements, repairing wear-and-tear damage,” says Raymond. “There was a lot of work needed on the muon chambers and the Tile Calorimeters, replacing faulty electronic elements; and a number of gas connections had to be replaced on both sides of the experiment, to avoid leaks.”

    With the work now complete and beams running through the LHC, most of the ATLAS Collaboration has turned their focus to the data. However Michel and his colleagues continue to look forward to their next trip underground. “We’re always planning ahead, thinking about the next shutdown and the ones after that,” concludes Raymond.

    See the full article here .

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
  • richardmitnick 12:12 pm on March 22, 2016 Permalink | Reply
    Tags: Accelerator Science, , ,   

    From Symmetry: “Why are particle accelerators so large?” 

    Symmetry Mag

    Symmetry

    03/22/16
    Sarah Charley

    The Large Hadron Collider at CERN is a whopping 27 kilometers in circumference. Edda Gschwendtner, physicist and project leader for CERN’s plasma wakefield acceleration experiment (AWAKE), explains why scientists use such huge machines.


    Access mp4 video here .

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles

    We can only see so much with the naked eye. To see things that are smaller, we use a microscope, and to see things that are further away, we use a telescope. The more powerful the tool, the more we can see.

    Particle accelerators are tools that allow us probe both the fundamental components of nature and the evolution and origin of all matter in the visible (and maybe even the invisible?) universe. The more powerful the accelerator, the further we can see into the infinitely small and the infinitely large.

    You can think about particle accelerators like a racetrack for particles. Racecars don’t start out going 200 miles per hour—they must gradually accelerate over time on either a large circular racetrack or a long, straight road.

    In physics, these two types of “tracks” are circular accelerators and linear accelerators.

    Particles in circular accelerators gradually gain energy as they race through an accelerating structure at a certain position in the ring. For instance, the protons in the LHC make 11,000 laps every second for 20 minutes before they reach their collision energy. During their journey, magnets guide the particles around the bends in the accelerator and keep them on course.

    But just like a car on a curvy mountain road, the particles’ energy is limited by the curves in the accelerators. If the turns are too tight or the magnets are too weak, the particles will eventually fly off course.

    Linear accelerators don’t have this problem, but they face an equally challenging aspect: particles in linear accelerators only have the length of the track where they pass through accelerating structures to reach their desired energy. Once they reach the end, that’s it.

    So if we want to look deeper into matter and further back toward the start of the universe, we have to go higher in energy, which means we need more powerful tools.

    One option is to build larger accelerators—linear accelerators hundreds of miles long or giant circular accelerators with long, mellow turns.

    We can also invest in our technology. We can develop accelerating structure techniques to rapidly and effectively accelerate particles in linear accelerators over a short distance. We can also design and build incredibly strong magnets—stronger than anything that exists today—that can bend ultra-high energy particles around the turns in circular accelerators.

    Realistically, the future tools we use to look into the infinitely small and infinitely large will involve a combination of technological advancement and large-scale engineering to bring us closer to understanding the unknown.

    Have a burning question about particle physics? Let us know via email or Twitter (using the hashtag #AskSymmetry). We might answer you in a future video!

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
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