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  • richardmitnick 4:08 pm on May 26, 2015 Permalink | Reply
    Tags: , , Particle Physics, , ,   

    From Symmetry: “A goldmine of scientific research” 

    Symmetry

    May 26, 2015
    Amelia Williamson Smith

    1
    Photo by Anna Davis

    The underground home of the LUX dark matter experiment has a rich scientific history.

    There’s more than gold in the Black Hills of South Dakota. For longer than five decades, the Homestake mine has hosted scientists searching for particles impossible to detect on Earth’s surface.

    It all began with the Davis Cavern.

    In the early 1960s, Ray Davis, a nuclear chemist at Brookhaven National Laboratory designed an experiment to detect particles produced in fusion reactions in the sun. The experiment would earn him a share of the Nobel Prize in Physics in 2002.

    Davis was searching for neutrinos, fundamental particles that had been discovered only a few years before. Neutrinos are very difficult to detect; they can pass through the entire Earth without bumping into another particle. But they are constantly streaming through us. So, with a big enough detector, Davis knew he could catch at least a few.

    Davis’ experiment had to be done deep underground; without the shielding of layers of rock and earth it would be flooded by the shower of cosmic rays also constantly raining from space.

    Davis put his first small prototype detector in a limestone mine near Akron, Ohio. But it was only about half a mile underground, not deep enough.

    “The only reason for mining deep into the earth was for something valuable like gold,” says Kenneth Lande, professor of physics at the University of Pennsylvania, who worked on the experiment with Davis. “And so a gold mine became the obvious place to look.”

    But there was no precedent for hosting a particle physics experiment in such a place. “There was no case where a physics group would appear at a working mine and say, ‘Can we move in please?’”

    Davis approached the Homestake Mining Company anyway, and the company agreed to excavate a cavern for the experiment.

    BNL funded the experiment. In 1965, it was installed in a cavern 4850 feet below the surface.

    The detector consisted of a 100,000-gallon tank of chlorine atoms. Davis had predicted that as solar neutrinos passed through the tank, one would occasionally collide with a chlorine atom, changing it to an argon atom. After letting the detector run for a couple of months at a time, Davis’ team would flush out the tank and count the argon atoms to determine how many neutrino interactions had occurred.

    “The detector had approximately 1031 atoms in it. One argon atom was produced every two days,” Lande says. “To design something that could do that kind of extraction was mind-boggling.”

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    Ray Davis. Courtesy of: Brookhaven National Laboratory

    A different kind of laboratory

    During the early years of the Davis experiment, around 2000 miners worked at the mine, along with engineers and geologists. The small group of scientists working on the Davis experiment would travel down into the mine with them.

    To go down the shaft to the 4850-foot level, they would get into what was called the “cage,” a 4.4-foot by 12.5-foot metal conveyance that held 36 people. The ride down, lit only by the glow of a couple of headlamps, took about five minutes, says Tom Regan, former operations safety manager and now safety consultant, who worked as a student laborer in the mine during the early years of the Davis experiment.

    Once they reached the 4850-foot level, the scientists walked across a rock dump. “It was guarded so a person couldn’t fall down the hole,” Regan says. “But you had to sometimes wait for a production train of rock or even loads of supplies or men or materials.”

    The Davis Cavern was 24 feet long, 24 feet wide, and 30 feet high. A small room off to the side held the group’s control system. “We were basically out of touch with the rest of the world when we were underground,” Lande says. “There was no difference between day and night, heat and cold, and snow and sunshine.”

    The miners and locals from Lead, South Dakota—the community surrounding the mine—were welcoming of the scientists and interested in their work, Lande says. “We’d go out to dinner at the local restaurant and we’d hear this hot conversation in the next booth, and they would be discussing black holes and neutron stars. So science became the talk of the small town.”

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    Davis Cavern, during the solar neutrino experiment. Photo by: Anna Davis

    The solar neutrino problem

    As the experiment began taking data, Davis’ group found they were detecting only about one-third the number of neutrinos predicted—a discrepancy that became known as the “solar neutrino problem.”

    Davis described the situation in his Nobel Prize biographical sketch: “My opinion in the early years was that something was wrong with the standard solar model; many physicists thought there was something wrong with my experiment.”

    However, every test of the experiment confirmed the results, and no problems were found with the model of the sun. Davis’ group began to suspect it was instead a problem with the neutrinos.

    This suspicion was confirmed in 2001, when the Sudbury Neutrino Observatory experiment [SNO] in Canada determined that as solar neutrinos travel through space, they oscillate, or change, between three flavors—electron, muon and tau. By the time neutrinos from the sun reach the Earth, they are an equal mixture of the three types.

    Sudbury Neutrino Observatory
    SNO

    The Davis experiment was sensitive only to electron neutrinos, so it was able to detect only one-third of the neutrinos from the sun. The solar neutrino problem was solved.

    5
    Davis Cavern, during a more recent expansion. Photo by: Matthew Kapust, Sanford Underground Research Facility

    A different kind of gold

    The Davis experiment ran for almost 40 years, until the mine closed in 2003.

    But the days of science in the Davis Cavern weren’t over. In 2006, the mining company donated Homestake to the state of South Dakota. It was renamed the Sanford Underground Research Facility.

    In 2009, many former Homestake miners became technicians on a $15.2 million project to renovate the experimental area. They completed the new 30,000-square-foot Davis Campus in 2012.

    Although scientists still ride in the cage to get down to the 4850-foot level of the mine, once they arrive it looks completely different.

    “It’s a very interesting contrast,” says Stanford University professor Thomas Shutt of SLAC National Accelerator Laboratory. “Going into the mine, it’s all mining carts, rust and rock, and then you get down to the Davis Campus, and it’s a really state-of-the-art facility.”

    The campus now contains block buildings with doors and windows. It has its own heating and air conditioning system, ventilation system, humidifiers and dust filters.

    The original Davis Cavern has been expanded and now houses the Large Underground Xenon experiment, the most sensitive detector yet searching for what many consider the most promising candidate for a type of dark matter particle.

    LUX Dark matter
    LUX

    Shielded from distracting background particles this far underground, scientists hope LUX will detect the rare interaction of dark matter particles with the nucleus of xenon atoms in the 368-kilogram tank.

    Another cavern nearby was excavated as part of the Davis Campus renovation project and now holds the Majorana Demonstrator experiment, which will soon start to examine whether neutrinos are their own antimatter partners.

    Majorano Demonstrator Experiment
    Majorano Demonstrator Experiment

    LUX began taking data in 2013. It is currently on its second run and will continue through spring 2016.

    After its current run, LUX will be replaced by the LUX-ZEPLIN, or LZ, experiment, which will be 50 times bigger in usable mass and several hundred times more sensitive than the current LUX results.

    LZ project
    LZ

    Science in the mine is still the talk of the town in Lead, says Carmen Carmona, an assistant project scientist at the University of California, Santa Barbara, who works on LUX. “When you go out on the streets and talk to people—especially the families of the miners from the gold mine days—they want to know how it is working underground now and how the experiment is going.”

    The spirit of cooperation between the mining community, the science community and the public community lives on, Regan says.

    “It’s been kind of a legacy to provide the beneficial space and be good neighbors and good hosts,” Regan says. “Our goal is for them to succeed, so we do everything we can to help and provide the best and safest place for them to do their good science.”

    6
    In 2010, Sanford Lab enlarged the Davis Cavern to support the Large Underground Xenon experiment. Matthew Kapust, Sanford Underground Research Facility

    7
    This cavern is being outfitted for the Compact Accelerator System Performing Astrophysical Research. CASPAR will use a low-powered accelerator to study what happens when stars die. Matthew Kapust, Sanford Underground Research Facility

    8
    Davis Cavern undergoes outfitting for the LUX experiment. Matthew Kapust, Sanford Underground Research Facility

    9
    Each day scientists working at the the Davis Campus pass this area, known as the Big X. The entrance to the Davis Campus is to the left; Yates Shaft is to the right. Matthew Kapust, Sanford Underground Research Facility

    10
    LUX researchers install the detector at the 4850 level. Matthew Kapust, Sanford Underground Research Facility

    11
    The Majorana Demonstrator experiment requires a very strict level of cleanliness. Researcher work in full clean room garb and assemble their detectors inside nitrogen-filled glove boxes. Matthew Kapust, Sanford Underground Research Facility

    12
    The LUX detector was built in a clean room on the surface and then brought underground. Matthew Kapust, Sanford Underground Research Facility

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 8:28 am on May 22, 2015 Permalink | Reply
    Tags: , , , , , Particle Physics   

    From CERN: “First images of collisions at 13 TeV” 

    CERN New Masthead

    21 May 2015
    Cian O’Luanaigh

    1
    Test collisions continue today at 13 TeV in the Large Hadron Collider (LHC) to prepare the detectors ALICE, ATLAS, CMS, LHCb, LHCf, MOEDAL and TOTEM for data-taking, planned for early June (Image: LHC page 1)

    Last night, protons collided in the Large Hadron Collider (LHC) at the record-breaking energy of 13 TeV for the first time. These test collisions were to set up systems that protect the machine and detectors from particles that stray from the edges of the beam.

    A key part of the process was the set-up of the collimators. These devices which absorb stray particles were adjusted in colliding-beam conditions. This set-up will give the accelerator team the data they need to ensure that the LHC magnets and detectors are fully protected.

    Today the tests continue. Colliding beams will stay in the LHC for several hours. The LHC Operations team will continue to monitor beam quality and optimisation of the set-up.

    This is an important part of the process that will allow the experimental teams running the detectors ALICE, ATLAS, CMS, LHCb, LHCf, MOEDAL and TOTEM to switch on their experiments fully. Data taking and the start of the LHC’s second run is planned for early June.

    2
    Protons collide at 13 TeV sending showers of particles through the ALICE detector (Image: ALICE)

    3
    Protons collide at 13 TeV sending showers of particles through the CMS detector (Image: CMS)

    4
    Protons collide at 13 TeV sending showers of particles through the ATLAS detector (Image: ATLAS)

    5
    Protons collide at 13 TeV sending showers of particles through the LHCb detector (Image: LHCb)

    6
    Protons collide at 13 TeV sending showers of particles through the TOTEM detector (Image: TOTEM)

    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

    LHC

    CERN LHC New
    CERN LHC Grand Tunnel

    LHC particles

    Quantum Diaries

     
  • richardmitnick 2:53 pm on May 13, 2015 Permalink | Reply
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    From FNAL: “Two Large Hadron Collider experiments first to observe rare subatomic process” 

    FNAL Home

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

    May 13, 2015
    MEDIA CONTACTS
    Andre Salles, Fermilab Office of Communication, 630-840-3351, media@fnal.gov
    Sarah Charley, US LHC/CERN, +41 22 767 2118, sarah.charley@cern.ch

    SCIENCE CONTACTS
    Joel Butler, CMS experiment, Fermilab, 630-651-4619, butler@fnal.gov
    Sarah Scalese, LHCb experiment, Syracuse University, 315-443-8085, sescales@syr.edu

    1
    2
    Event displays from the CMS (above) and LHCb (below) experiments on the Large Hadron Collider show examples of collisions that produced candidates for the rare decay of the Bs particle, predicted and observed to occur only about four times out of a billion. Images: CMS/LHCb collaborations

    Two experiments at the Large Hadron Collider [LHC] at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, have combined their results and observed a previously unseen subatomic process.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC

    As published in the journal Nature this week, a joint analysis by the CMS and LHCb collaborations has established a new and extremely rare decay of the Bs particle (a heavy composite particle consisting of a bottom antiquark and a strange quark) into two muons. Theorists had predicted that this decay would only occur about four times out of a billion, and that is roughly what the two experiments observed.

    CERN CMS Detector
    CMS

    CERN LHCb New II
    LHCb

    “It’s amazing that this theoretical prediction is so accurate and even more amazing that we can actually observe it at all,” said Syracuse University Professor Sheldon Stone, a member of the LHCb collaboration. “This is a great triumph for the LHC and both experiments.”

    LHCb and CMS both study the properties of particles to search for cracks in the Standard Model, our best description so far of the behavior of all directly observable matter in the universe.

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    Standard Model of Particle Physics. The diagram shows the elementary particles of the Standard Model (the Higgs boson, the three generations of quarks and leptons, and the gauge bosons), including their names, masses, spins, charges, chiralities, and interactions with the strong, weak and electromagnetic forces. It also depicts the crucial role of the Higgs boson in electroweak symmetry breaking, and shows how the properties of the various particles differ in the (high-energy) symmetric phase (top) and the (low-energy) broken-symmetry phase (bottom).

    The Standard Model is known to be incomplete since it does not address issues such as the presence of dark matter or the abundance of matter over antimatter in our universe. Any deviations from this model could be evidence of new physics at play, such as new particles or forces that could provide answers to these mysteries.

    “Many theories that propose to extend the Standard Model also predict an increase in this Bs decay rate,” said Fermilab’s Joel Butler of the CMS experiment. “This new result allows us to discount or severely limit the parameters of most of these theories. Any viable theory must predict a change small enough to be accommodated by the remaining uncertainty.”

    Researchers at the LHC are particularly interested in particles containing bottom quarks because they are easy to detect, abundantly produced and have a relatively long lifespan, according to Stone.

    “We also know that Bs mesons oscillate between their matter and their antimatter counterparts, a process first discovered at Fermilab in 2006,” Stone said. “Studying the properties of B mesons will help us understand the imbalance of matter and antimatter in the universe.”

    That imbalance is a mystery scientists are working to unravel. The big bang that created the universe should have resulted in equal amounts of matter and antimatter, annihilating each other on contact. But matter prevails, and scientists have not yet discovered the mechanism that made that possible.

    “The LHC will soon begin a new run at higher energy and intensity,” Butler said. “The precision with which this decay is measured will improve, further limiting the viable Standard Model extensions. And of course, we always hope to see the new physics directly in the form of new particles or forces.”

    This discovery grew from analysis of data taken in 2011 and 2012 by both experiments. Scientists also saw some evidence for this same process for the Bd particle, a similar particle consisting of a bottom antiquark and a down quark. However, this process is much more rare and predicted to occur only once out of every 10 billion decays. More data will be needed to conclusively establish its decay to two muons.

    The U.S. Department of Energy Office of Science provides funding for the U.S. contributions to the CMS experiment. The National Science Foundation provides funding for the U.S. contributions to the CMS and LHCb experiments. Together, the CMS and LHCb collaborations include more than 4,500 scientists from more than 250 institutions in 44 countries.

    The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

    The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2015, its budget is $7.3 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives about 48,000 competitive proposals for funding, and makes about 11,000 new funding awards. NSF also awards about $626 million in professional and service contracts yearly.

    CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Israel, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a Candidate for Accession. Serbia is an Associate Member in the pre-stage to Membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Union, JINR and UNESCO have Observer Status.

    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 6:44 pm on May 12, 2015 Permalink | Reply
    Tags: , Particle Physics,   

    From phys.org: “New shield makes certain types of searches for first time” 

    physdotorg
    phys.org

    May 12, 2015
    No Writer Credit

    1
    Inner three layers of the magnetic shield (also known as the insert), and the cylindrical layer with 780 copper rods. The cylindrical layer is used to generate a very uniform magnetic field, which is necessary for EDM experiments. Also shown are two measurement devices: A mercury magnetometer is placed between the wooden support structure, and a high precision pendulum device, which is used for the absolute alignment of conventional magnetic field probes, is on top of the support table. Credit: Technische Universität Müchen

    The Standard Model of particle physics, sometimes called “The Theory of Almost Everything,” is the best set of equations to date that describes the universe’s fundamental particles and how they interact.

    2
    Standard Model of Particle Physics. The diagram shows the elementary particles of the Standard Model (the Higgs boson, the three generations of quarks and leptons, and the gauge bosons), including their names, masses, spins, charges, chiralities, and interactions with the strong, weak and electromagnetic forces. It also depicts the crucial role of the Higgs boson in electroweak symmetry breaking, and shows how the properties of the various particles differ in the (high-energy) symmetric phase (top) and the (low-energy) broken-symmetry phase (bottom).

    Yet the theory has holes—including the absence of an adequate explanation for gravity, the inability to explain the asymmetry between matter and antimatter in the early universe, which gave rise to the stars and galaxies, and the failure to identify fundamental dark matter particles or account for dark energy.

    Researchers now have a new tool to aid in the search for physics beyond the good, but yet incomplete Standard Model. An international team of scientists has designed and tested a magnetic shield that is the first to achieve an extremely low magnetic field over a large volume. The device provides more than 10 times better magnetic shielding than previous state-of-the art shields. The record-setting performance makes it possible for scientists to measure certain properties of fundamental particles at higher levels of precision—which in turn could reveal previously hidden physics and set parameters in the search for new particles.

    The researchers describe the new magnetic shield in a paper in the Journal of Applied Physics.

    High precision measurements are one of three frontiers to search for physics beyond the Standard Model, explained Tobias Lins, a doctoral student who worked on the new magnetic shield in the research lab of Professor Peter Fierlinger at the Technische Universität München in Germany. The precision measurements complement other methods to search for new physics, including slamming particles together in a collider to generate new, high-energy particles, and peering into space to catch signals from the early universe.

    “Precision experiments are able to probe nature up to energy scales which might not be accessible by current and next generation collider experiments,” Lins said. That’s because the existence of exotic new particles can slightly alter the properties of already known particles. A tiny deviation from the expected properties may indicate that an as-yet-undiscovered fundamental particle inhabits the “particle zoo.”

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    An international team of physicists has developed a shielding that dampens low frequency magnetic fields more than a million-fold. Using this mechanism, they have created a space that boasts the weakest magnetic field of our solar system. The physicists now intend to carry out precision experiments there. Credit: Astrid Eckert / TUM

    Constructing the Shield

    The researchers built the new shield out of several layers of a special alloy, composed of nickel and iron, that has a high degree of magnetic permeability—meaning it can act like a sponge to absorb and redirect an applied magnetic field, like the earth’s own magnetic field or fields generated by equipment such as motors and transformers.

    “The apparatus might be compared to cuboid Russian nesting dolls,” Lins said. “Like the dolls, most layers can be used individually and with an increasing number of layers the inside is more and more protected.”

    The team’s big breakthrough came from in-depth numerical modeling of the arrangement of the precision treated magnetizable alloy, resulting in significantly optimized design details, like thickness, connections and spacing of layers.

    The materials in magnetic shields change their magnetization due to environmental influences, like temperature changes and vibrations caused by passing cars, and these shifts can be passed to the inside of the shield. The thinner sheets in the new design enabled a better balancing of the magnetic field in the metal, resulting in the smallest and most homogenous magnetic field ever created within the shielded space, even beating the average ambient magnetic field of the interstellar medium.

    New Experiments Ahead

    Plans are already underway to use the new magnetic shield in an experiment to test limits for the distribution of charges (called the electric dipole moment or EDM) of an isotope of xenon. An EDM that is higher than predicted by the Standard Model could signal the existence of a new particle whose mass is linked to the amount by which the EDM deviates from the expected value.

    The researchers also want to use a modified SQUID detector—which can detect extremely subtle magnetic fields—to search for long theorized, but never detected magnetic monopoles. Within the magnetically quiet space inside the shield, a monopole passing by the SQUID might produce a magnetic field higher than the background noise level, Lins said.

    See the full article here.

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 1:17 pm on April 23, 2015 Permalink | Reply
    Tags: , , , Particle Physics   

    From Symmetry: “Extreme cold and shipwreck lead” 

    Symmetry

    April 23, 2015
    Lauren Biron

    Scientists have proven the concept of the CUORE experiment, which will study neutrinos with the world’s coldest detector and ancient lead.

    1
    Courtesy of the CUORE collaboration

    Scientists on an experiment in Italy are looking for a process so rare, it is thought to occur less than once every trillion, trillion years. To find it, they will create the single coldest cubic meter in the universe.

    The experiment, the Cryogenic Underground Observatory for Rare Events, will begin by the end of the year, scientists recently announced after a smaller version demonstrated the feasibility of the design.

    The project, based at Gran Sasso National Laboratory, will examine a property of ghostly neutrinos by looking for a process called neutrinoless double beta decay. If scientists find it, it could be a clue as to why there is more matter than antimatter in the universe–and show that neutrinos get their mass in a way that’s different from all other particles.

    The full CUORE experiment requires 19 towers of tellurium dioxide crystals, each made of 52 blocks just smaller than a Rubik’s cube. Physicists will place these towers into a refrigerator called a cryostat and cool it to 10 millikelvin, barely above absolute zero. The cryostat will eclipse even the chill of empty space, which registers a toasty 2.7 Kelvin (minus 455 degrees Fahrenheit).

    CUORE uses the cold crystals to search for a small change in temperature caused by these rare nuclear decays. Unlike ordinary beta decays, in which electrons and antineutrinos share energy, the neutrinoless double beta decay produces two electrons, but no neutrinos at all. It is as if the two antineutrinos that should have been produced annihilate one another inside the nucleus.

    “This would be really cool because it would mean that the neutrino and the antineutrino are the same particle, and most of the time we just can’t tell the difference,” says Lindley Winslow, a professor at MIT and one of over 160 scientists working on CUORE.

    Neutrinos could be the only fundamental particles of matter to have this strange property.

    For the past two years, scientists collected data on just one of the crystal towers housed in a smaller cryostat, a project called CUORE-0. The most recent result establishes the most sensitive limits for seeing neutrinoless beta decay in tellurium crystals. In addition, the researchers verified that the techniques developed to construct CUORE work well and reduce background radiation prior to the full experiment coming online.

    “It’s a great result for Te-130, We are also very excited that we were able to demonstrate that what’s coming online with CUORE is what we hoped it would be,” says Reina Maruyama, professor of physics at Yale University and a member of the CUORE Physics Board. “We look forward to shattering our own result from CUORE-0 once CUORE comes to life”

    Avoiding radioactive contamination and shielding the experiment from outside sources that might mimic the telltale energy signature CUORE is searching for is a priority. The mountains at Gran Sasso will provide one layer of shielding from cosmic bombardment, but the CUORE cryostat will also get a second layer of protection against the minor radiation of the mountain itself. Ancient Roman lead ingots, salvaged from a shipwreck that occurred more than 2000 years ago, have been melted down into a shield that will cocoon the crystal towers.

    Lead excels at blocking radiation but can itself become slightly radioactive when hit by cosmic rays. The ingots that sat at the bottom of the sea for two millennia have been spared cosmic bombardment and provide very clean, if somewhat exotic, shielding material.

    The next step for CUORE will be to finish commissioning the powerful refrigerator, the largest of its kind. The cryostat must remain stable even with the tons of material inside. After the detector is installed and the cryostat cooled, it will likely take between six months and a year to find the ultimate sensitivity, measure contamination (if there is any), and show that the detector works perfectly, says Yury Kolomensky, professor of physics at the University of California, Berkeley, and the US spokesperson for the CUORE collaboration. Then it will take data for five years.

    “And then we hope to come back with either a discovery [of neutrinoless double beta decay]–or not. And if not, that means we have shrunk the size of the haystack by a factor of 20,” Kolomensky says.

    If CUORE goes well, it could find itself a contender for the next generation of neutrinoless double beta decay experiments, something Kolomensky says the nuclear physics community plans to decide over the next two to three years. CUORE uses tellurium, a plentiful isotope that has good energy resolution, meaning scientists can tell precisely where the peak is and what caused it. Other large-scale neutrinoless double beta decay experiments use germanium or xenon instead.

    “The worldwide community is looking at all the technologies very carefully,” Kolomensky says. “If our detector works as advertised at this scale, we’ll be in a very strong position to build an even better detector.”

    CUORE’s journey has already been more than 30 years in the making, according to Oliviero Cremonesi, spokesperson for the collaboration.

    “It’s very emotional for me. We started in the ‘80s with milligram prototypes, and now we have a ton-size detector and a unique cryogenic system,” Cremonesi says. “Even more exciting is the knowledge that this adventure could continue in the future.”

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 11:21 am on April 22, 2015 Permalink | Reply
    Tags: , FNAL ICARUS, , Particle Physics   

    From FNAL: “ICARUS neutrino experiment to move to Fermilab” 

    FNAL Home

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

    April 22, 2015

    Andre Salles, Fermilab Office of Communication, 630-840-3351, media@fnal.gov
    Vincenzo Napolano, INFN Communication Office, +39066868162, +393472994985, vincenzo.napolano@presid.infn.it, comunicazione@presid.infn.it
    CERN Press Office, +41227673432, +41227672141, press.office@cern.ch

    1
    A view of the top of the ICARUS detector in place at INFN’s Gran Sasso National Laboratory in Italy. The 760-ton detector has been removed from Gran Sasso and shipped to CERN for upgrades, and will come to Fermilab in 2017 to become part of the laboratory’s short-baseline neutrino program. Photo: INFN.

    A group of scientists led by Nobel laureate Carlo Rubbia will transport the world’s largest liquid-argon neutrino detector across the Atlantic Ocean to its new home at the U.S. Department of Energy’s Fermi National Accelerator Laboratory.

    The 760-ton, 65-foot-long detector took data for the ICARUS experiment at the Italian Institute for Nuclear Physics’ (INFN) Gran Sasso National Laboratory in Italy from 2010 to 2014, using a beam of neutrinos sent through the Earth from CERN. The detector is now being refurbished at CERN, where it is the first beneficiary of a new test facility for neutrino detectors.

    INFN Gran Sasso ICARUS
    ICARUS at INFN Gran Sasso

    When it arrives at Fermilab, the detector will become part of an on-site suite of three experiments dedicated to studying neutrinos, ghostly particles that are all around us but have given up few of their secrets.

    All three detectors will be filled with liquid argon, which enables the use of state-of-the-art time projection technology, drawing charged particles created in neutrino interactions toward planes of fine wires that can capture a 3-D image of the tracks those particles leave. Each detector will contribute different yet complementary results to the hunt for a fourth type of neutrino.

    “The liquid-argon time projection chamber is a new and very promising technology that we originally developed in the ICARUS collaboration from an initial table-top experiment all the way to a large neutrino detector,” Rubbia said. “It is expected that it will become the leading technology for large liquid-argon detectors, with its ability to record ionizing tracks with millimeter precision.”

    Fermilab operates two powerful neutrino beams and is in the process of developing a third, making it the perfect place for the ICARUS detector to continue its scientific exploration. Scientists plan to transport the detector to the United States in 2017.

    A planned sequence of three liquid-argon detectors will provide new insights into the three known types of neutrinos and seek a yet unseen fourth type, following hints from other experiments over the past two decades.

    Many theories in particle physics predict the existence of a so-called “sterile” neutrino, which would behave differently from the three known types and, if it exists, could provide a route to understanding the mysterious dark matter that makes up 25 percent of the universe. Discovering this fourth type of neutrino would revolutionize physics, changing scientists’ picture of the universe and how it works.

    “The arrival of ICARUS and the construction of this on-site research program is a lofty goal in itself,” said Fermilab Director Nigel Lockyer. “But it is also the first step forward in Fermilab’s plan to host a truly international neutrino facility, with the help of our partners from around the world. The future of neutrino research in the United States is bright.”

    Fermilab’s proposed suite of experiments includes a new 260-ton Short Baseline Neutrino Detector (SBND), which will sit closest to the source of the particle beam. This detector is under construction by a team of scientists and engineers from universities and national laboratories in the United States and Europe.

    The neutrino beam will then encounter the already-completed 170-ton MicroBooNE detector, which will begin operation next year.

    FNAL MicroBooNE
    MicroBooNE

    The final piece is the ICARUS detector, which will be housed in a new building to be constructed on site.

    Construction on the ICARUS and SBND buildings is scheduled to begin later this year, and the three experiments should all be operational by 2018. The three collaborations include scientists from 45 institutions in six countries.

    The move of the ICARUS detector is a sterling example of cooperation between countries (and between three scientific collaborations) to achieve a global physics goal. The current European strategy for particle physics, adopted by the CERN Council, recommends that Europe play an active part in neutrino experiments in other parts of the world, rather than carry them out at CERN.

    The U.S. particle physics community has adopted the P5 (Particle Physics Project Prioritization Panel) plan, which calls for a world-class long-distance neutrino facility to be built at Fermilab and operated by an international collaboration. Fermilab, CERN, INFN and many other international institutions are expected to partner in this endeavour.

    Knowledge gained by operating the suite of three liquid-argon experiments will be important in the development of the DUNE experiment at the planned long-distance facility at Fermilab. DUNE will be the largest neutrino oscillation experiment ever built, sending particles 800 miles from Fermilab to a 40,000-ton liquid-argon detector at the Sanford Underground Research Facility in South Dakota.

    Sanford Underground Research Facility Interior
    Sanford Underground Research Facility

    For more information, read this article from symmetry magazine.

    “The journey of ICARUS from Italy to CERN to the U.S. is a great example of the global planning in particle physics,” said CERN Director General Rolf Heuer. “U.S. participation in the LHC and European participation in Fermilab’s neutrino program are integral parts of both European and U.S. strategies. I am pleased that CERN has been able to provide the glue that is allowing DUNE to get off the ground with the transport of ICARUS.”

    “The ICARUS T600 is the only detector in the world with more than 600 tons of argon to have been successfully operated,” said INFN’s deputy president Antonio Masiero “ICARUS uses a high-precision, innovative technique to detect neutrinos artificially produced in an accelerator. This technique, developed at INFN and first successfully put into operation in the ICARUS experiment at the INFN’s Gran Sasso National Laboratory, will make in the new dedicated facility at Fermilab a fundamental contribution to neutrino research.”

    The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

    CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Israel, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a Candidate for Accession. Serbia is an Associate Member in the pre-stage to Membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Union, JINR and UNESCO have Observer Status.

    The Italian Institute for Nuclear Physics (INFN) manages and supports theoretical and experimental research in the fields of subnuclear, nuclear, astroparticle physics in Italy under the supervision of the Ministry of Education, Universities and Research (MIUR). INFN carries out research activities at four national laboratories, in Catania, Frascati, Legnaro and Gran Sasso and 20 divisions, based at university physics departments in different cities of Italy. http://www.infn.it

    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 10:37 am on April 16, 2015 Permalink | Reply
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    From FNAL: “Physics in a Nutshell Particle – beams and the scattering process” 

    FNAL Home

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

    April 16, 2015
    Roger Dixon

    1
    The Main Injector is the flagship accelerator at Fermilab. Over the coming months, this column will review how machines such as this one achieve high-energy particle beams. Photo: Reidar Hahn

    Much of the information we gather from the physical world comes to us by a scattering process. Scattering occurs when a beam consisting of light or charged particles strikes a target. The incident particle and target can simply recoil from the interaction, or other additional particles can materialize out of the energy of the collision. Information about the target and beam is carried away in the recoiling particles.

    Consider an everyday example: A beam of sunlight strikes a flower and scatters off the magnificent petals in the form of light particles at particular frequencies, which make their way to our eyes. From there the information is transmitted to the brain, which compares the data with existing data in the brain, and we recognize that we are looking at a beautiful flower.

    We gather information about much smaller, subatomic objects in the same way. A beam from a particle accelerator strikes a target, and a detector records information about the recoiling debris: angles, momentum, energy of the scattered particles. The detector (an eye) registers the raw information and processes it before sending it on to a computer (a brain), which seeks recognizable patterns in the data that reveal basic aspects of the beam and the target. Through the ensuing analysis, we can distinguish between particles and measure their properties, such as charge, mass and spin, among others.

    Order discerned in this manner is a fundamental basis for our knowledge of the physical world. A subtlety of the process is that the incident beam must have specific properties in order to reveal the type of information we want with the desired level of detail.

    To explore the details of very small particles, scientists need to create beams with high energies. Electric fields are used to accelerate charged particles. An electric field resides between the two poles of a battery. The unit of energy used for beams of charged particle is the electronvolt (eV). One eV is the energy gained by an electron when it is accelerated through a one-volt potential.

    One way to create such a potential is with a 1.5-volt flashlight battery. An electron passing between the poles would gain 1.5 eV. However, a battery is not the best way to accelerate charged particles. To achieve 1 trillion electronvolts (1 TeV) with flashlight batteries would require 667 billion batteries, and the battery string would be roughly 24 million miles long.

    The good news is that I found batteries on sale for $1.15 each if we act fast. However, a quick review of the numbers reveals that batteries simply won’t work due to both cost and environmental issues. We need a better solution for accelerating our beams.

    In future columns I will summarize more reasonable solutions for achieving high-energy beams. We will discover that modern accelerators use a combination of brute force and ingenuity. What could be more fun?

    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 4:01 pm on April 14, 2015 Permalink | Reply
    Tags: , , Particle Physics   

    From BNL: “Relativistic Heavy Ion Collider Smashes Record for Polarized Proton Luminosity at 200 GeV Collision Energy” 

    Brookhaven Lab

    April 14, 2015
    Karen McNulty Walsh, (631) 344-8350 or Peter Genzer, (631) 344-3174

    1
    Aerial view of he Relativistic Heavy Ion Collider

    2
    RHIC is producing more than twice as many proton-proton collisions per week during the current run as it did in 2012, the last run dedicated to polarized proton collisions.

    The Relativistic Heavy Ion Collider (RHIC), a powerful particle accelerator for nuclear physics research at the U.S. Department of Energy’s Brookhaven National Laboratory, just shattered its own record for producing polarized proton collisions at 200-giga-electron-volt (GeV) collision energy. In the experimental run currently underway at this two-ringed, 2.4-mile-circumference particle collider, accelerator physicists are now delivering 1200 billion of these subatomic smashups per week—more than double the number routinely achieved in 2012, the last run dedicated to polarized proton experiments at this collision energy.

    BNL RHIC Campus
    BNL RHIC
    RHIC

    The achievement is in part the result of a method called “electron lensing,” which uses negatively charged electrons to compensate for the tendency of the positively charged protons in one circulating beam to repel the like-charged protons in the other beam when two beams circulating in opposite directions pass through one another in the collider .

    _______________________________________________________________
    Electron Lenses

    Electron lenses use the attractive force negatively charged electrons exert on positively charged protons to compensate for the tendency of the protons in one circulating beam to repel protons in the other. In this context, the lens is a low-energy electron beam that collides with the proton beam. The electron beam has a current and transverse profile that create the same force for a proton passing through it as the proton experiences when passing through the other proton beam, but with the opposite sign. So the negatively charged beam counteracts the repulsive force experienced by the protons.
    _______________________________________________________________

    “In 2012, these beam-beam interactions limited our ability to produce high collision rates,” said Wolfram Fischer, Accelerator Division Head for Brookhaven’s Collider-Accelerator Department. So the RHIC team commissioned electron lenses and a new lattice to mitigate the beam-beam effect.

    “RHIC is the first collider to use electron lenses for head-on beam-beam compensation,” Fischer said. “From what we see so far, the electron lenses appear to be doing what they were designed for.”

    The team also upgraded the source that produces the polarized protons to generate and feed more of these particles into the circulating beams, and made other improvements in the RHIC accelerator chain to achieve the higher collision rates (or as physicists call it, luminosity).

    More collisions, more data, more science

    “The increased luminosity will generate high volumes of data rapidly, giving us time to achieve several high-priority science goals in a single run at RHIC,” said Berndt Mueller, the Associate Director for Nuclear and Particle Physics at Brookhaven Lab. “By allowing more science to be done in a fixed number of running weeks, the luminosity increase provides a richer return on the investments made by the nation in the science program at RHIC.”

    During the initial stage of the run, RHIC physicists are colliding high-energy 200 GeV polarized protons—protons whose individual spins are aligned in a particular direction—with another proton beam to tease out how the protons’ inner building blocks, quarks and gluons, contribute to overall proton spin—a long-standing physics mystery. RHIC was the first machine to reveal that gluons play an important role in this intrinsic particle property. The new results will improve on the precision of those measurements. They will also allow scientists to study the coupling between the spin and momentum of the quarks.

    With RHIC on track to another year of record performance, scientists are looking forward to a wealth of new insights from this year’s data.

    Research at RHIC, a DOE Office of Science User Facility, and upgrades to its infrastructure are funded primarily by the DOE Office of Science.

    Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

    See the full article here.

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    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
    i1

     
  • richardmitnick 9:38 am on April 9, 2015 Permalink | Reply
    Tags: , , , , , Particle Physics   

    From FNAL- “Frontier Science Result: CDF – Happy hunting grounds 

    FNAL Home

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

    April 9, 2015
    Fabrizio Margaroli and Andy Beretvas

    1
    This artistic view of a Feynman diagram shows the process of proton colliding with an antiproton, producing a W’, which then decays into a top quark and an antibottom quark.

    We understand nature in terms of elementary particles interacting through a set of well-known forces, which are mediated by other particles. These are the graviton (mediator of gravity), the photon (mediator of electromagnetism), the gluon (mediator of the strong force), the W and Z bosons (mediators of the weak force) and the Higgs boson. We produce and detect these particles (except the graviton) in large numbers at colliders around the world.

    But is that all the universe is made of — a handful of different types of particles? We have good reasons to believe that this is not the case. New forces can exist, and the corresponding mediating particles could be seen at colliders. However, such particles have been hunted extensively at the Large Hadron Collider without success so far.

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

    If new forces are hiding so well from physicists’ determination to discover them, either they would have to be mediated by very massive bosons or these bosons would have to interact very weakly with ordinary stuff.

    The W and Z boson serve as a good model for this kind of exotic stuff: In fact they are both very heavy compared to their peers and interact weakly with ordinary matter. They live very shortly before decaying into more “mundane” particles, most of the time quarks. If new forces were to exist with such properties, then the LHC would not be the best hunting ground because of its enormous production rate of quarks from ordinary forces.

    A new analysis of Tevatron data performed by the CDF collaboration searches for the existence of new electrically charged, massive particles (a W’ boson) decaying into a top and a bottom quark. Top and bottom quarks leave striking signatures in the detector; W’ events would resemble ordinary production of such quarks if not for the extra energy provided by the decay of the parent particle.

    FNAL Tevatron
    FNAL Tevatron machine
    Tevatron

    FNAL CDF
    CDF part of the Tevatron

    The search for a W’ with data from the CDF experiment turns out to be the most sensitive for such a heavy particle with mass below 650 GeV (approximately 700 times the proton mass). Unfortunately, no surprise turned out from CDF data. The ball is now again in the hands of the LHC experiments!

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

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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 10:48 am on March 31, 2015 Permalink | Reply
    Tags: , , , , Particle Physics   

    From ALICE at CERN: “Interview with Savas Dimopoulos” 

    CERN New Masthead

    CERN ALICE Icon HUGE

    24 March 2015
    Panos Charitos

    1
    Savas Dimopoulos

    Savas Dimopoulos, professor at Stanford University, is searching for answers to some of the most profound mysteries of nature. In this interview we discuss the recent findings of the LHC and his expectations from future HEP experiments, the quest for “truth” that drives our scientific endeavours, as well as the relation between science and art.

    P.C. Why did you decide to become a physicist?

    S.D. What attracted me to physics and mathematics was the truth of the statements made in these disciplines. This dates back to my childhood. I was born in Constantinople, and my family moved to Athens when I was twelve. It was a time of great turmoil and I witnessed political tensions, people on the left and on the right were expressing opposing arguments that both seemed reasonable to me.

    I decided to go into a discipline that seeks the absolute truth: a truth that does not depend on the eloquence of the speaker. That limited my choices to mathematics and physics. I finally decided to study physics, as I had doubts about the certainty of truth in mathematics; in physics, in addition to mathematical proofs, the experiments add an extra layer of certainty that brings us closer to the truth.

    I was enamoured of the fact that through physics we can explain all phenomena from very few principles, as nature turns out to be exceedingly simple in principles and exceedingly complex in phenomena. The laws of nature can be written down on a single piece of paper and explain everything that we have seen so far in the universe. This is the magic of theory: it compactifies facts and reduces them to a handful of principles from which everything can be derived.

    P.C. You referred to the balance between experiment and theory, but it somehow seems that you were more intrigued by the latter. What attracted you to what is now called theoretical physics?

    S.D. In the beginning, I had not decided whether I was going to be a theorist or an experimentalist. I went to a high-school without laboratories in Greece. The first time I had the chance to work in a laboratory was as a student at the university. That’s when I realised that I lacked the talent to be an experimentalist and felt that I was better in theory.

    At the time, I thought that the truth of mathematics exists only in our human brains, whereas physics is independent of human existence and therefore the ultimate discipline for the search for the absolute and most important truths. Plato believed that mathematical reality in some sense exists in the so-called platonic world of ideas, where objects on earth have their idealized counterparts. A sphere, for example, is never perfect in real life but in the platonic world, which we call mathematics, perfectly round spheres exist. As mathematical entities are not necessarily realized in nature, I felt uncomfortable as a child to just focus on mathematics. However, I think that it is an amazing language. The rules are well defined and once you pose the right question anybody can follow the steps to find the correct answer, even computers.

    P.C. Do you think that, besides experiments, mathematics is also another way to control our theories?

    S.D. You are absolutely right. Mathematics is crucial for controlling the truth because it is not a random game. You start with a few axioms, and, as long as they are self-consistent, you can produce theorems and derive truths that follow from them. In that sense, mathematics is very important to theoreticians, as mathematical consistency is a huge constraint on our theoretical ideas.

    P.C. What is the situation today in theoretical physics, following the recent results of the LHC?

    S.D. We are now standing at a crossroads, with one path leading to naturalness and the other to the multiverse or something else. It is very exciting, we are testing if the idea of naturalness can be applied to the hierarchy problem – which is the disparity between the weak and gravitational forces. In the next several years, the LHC will be the epicentre of excitement, because it is testing such a fundamental principle and such a dichotomy in physics.

    In the light of these data, physicists react in different ways. As I often emphasize in my recent talks, the state of beyond Standard Model physics after the LHC8 can be compared to headless chickens running in all possible directions.

    4
    Standard Model of Particle Physics. The diagram shows the elementary particles of the Standard Model (the Higgs boson, the three generations of quarks and leptons, and the gauge bosons), including their names, masses, spins, charges, chiralities, and interactions with the strong, weak and electromagnetic forces. It also depicts the crucial role of the Higgs boson in electroweak symmetry breaking, and shows how the properties of the various particles differ in the (high-energy) symmetric phase (top) and the (low-energy) broken-symmetry phase (bottom)

    What is more interesting, headless chickens can live for up to two years; that is also the timescale which we need to get more results from the second run of the LHC. This run will indicate the research that we will pursue in the coming decades.

    2
    Mixed reactions should not frighten us, as they characterize every scientific revolution.

    P.C. Why do you believe there is so much enthusiasm for the search of supersymmetry at the LHC?

    Supersymmetry standard model
    Standard Model of Supersymmetry

    S.D. People are enthusiastic about the possibility of discovering supersymmetry for a number of reasons. In the early 1990s, LEP measured the strengths of the strong and weak electromagnetic interactions and discovered that supersymmetric grand unification is favoured over the non-supersymmetric one. That was a great source of excitement, and theorists looked forward to discovering the super-partners at LEP, LEP 2, or at the LHC. However, no hint of supersymmetry was found after the first collisions at the LHC8 energies.

    CERN LEP
    CERN/LEP

    This story reminds me one of Sherlock Holmes’ stories where he points out “the curious incident of the dog in the night-time”, the incident being that the dog did nothing. In the same way, the absence of supersymmetry at the energies explored so far at the LHC can teach us many things. Supersymmetry is one of the rare ideas that is so important, that even its absence is worth knowing about.

    In addition to that, there is also a sociological aspect to the popularity of supersymmetry: it is an easy theory to work with, and, as a result, it can be tested experimentally in great detail, unlike other alternatives to the hierarchy problem.

    Because of these reasons, the search for supersymmetry is the [?]primary aim of the LHC. In the next years we should have a better idea of the path chosen by nature and we may be talking with enthusiasm about the discovery of the first supersymmetric particle. In the best case scenario, though, our theories will be proven wrong, and we will discover something unanticipated, something truly revolutionary as was the case with quantum mechanics.

    P.C. How did it feel to have your prediction of unification of couplings confirmed by experiment?

    S.D. Having your theory confirmed by experiment feels like a present that you didn’t deserve. When we do science on a day-to-day basis, it’s sort of like a puzzle – this very intricate game with strict rules. It’s like nature is a giant puzzle and mathematics is the language of nature. When a mathematical theory is verified by experiment, you feel awe. It somehow becomes real. You get amazed when you realize that all these games you have been playing are not just games but actually describe nature.

    P.C. Do you think LHC will have the last word or will we also need to design new experiments?

    S.D. There are two directions that we should pursue vigorously. One is to continue with colliders, and go to much higher energy. The other is to design new experiments, as there are some great theoretical ideas that cannot be tested in colliders. For example, some very weakly interacting new particles such as the axion can only be discovered in low energy, tabletop, small-scale experiments.

    There can be forces that are too weak to be discovered in colliders but can nevertheless be observed by testing gravity-like forces in small scale. For example, one can look for deviations from Newton’s law at short distances. In addition to the theoretical importance, many fields (i.e. condensed matter physics, atomic physics, quantum information) have made great progress in precision studies, and these new techniques are begging to be used for fundamental discoveries. They also have the sociological advantage of shorter timescales, typically less than five years, compared to those between two consecutive colliders, which can be decades.

    Another interesting point is that you can roughly separate physics to two periods. Before WWII a number of techniques were used to explore the truth, and the job of theoreticians was both to come up with theoretical ideas and to design experiments to test them. Enrico Fermi and Felix Bloch, for example, did not just do theory; they came up with experiments and, in some cases, even conducted them themselves. After the War, fundamental physics started focusing increasingly on the high energy frontier. This has been a golden road, as the recent discovery of the Higgs shows. Nevertheless, in the long timescale between consecutive colliders, it will be exciting to look for new physics using low energy experiments.

    P.C. Do you think that we still learn something, even when our theories are proven wrong? Is this another step bringing us closer to truth?

    S.D. Absolutely. Truth is both discovering new things and proving that some preconceptions, speculations, or theories are wrong. For example, the idea of the aether seemed plausible at a time, as it was logical to assume that electromagnetic waves need a medium, but it was disproved by the Michelson–Morley experiment. In this case, it was the non-discovery of something that created the big earthquake that led to relativity. Knowing what is false can be as important as knowing what is true.

    3

    P.C. What drives people to formulate new theories and models?

    S.D. One obvious reason is the inconsistency of an existing theory with data. The Standard Model has survived every laboratory test so far and in some cases the validity of its predictions has been tested to 12 decimal precision. It nevertheless fails to explain roughly 95% of our Cosmos. It does not explain Dark Matter or what the origin of Dark Energy is. For the latter, the SM prediction is at least 60 orders of magnitude larger than what we observe it to be. In addition to all this, we eventually run into theoretical problems once we extrapolate the theory to high energies.

    The other motivations are beauty and economy. In the context of physics, the idea of beauty has a relatively precise meaning: it involves symmetry, i.e. the idea that one object appears the same from different perspectives. Economy refers to economy of structure, particles, and parameters. Ideally, there are as few “moving parts” postulated into the theory as possible. In that sense, it is hard to believe that the Standard Model, despite being an amazing theory, is fundamental, because it has over twenty parameters and tens of particles. There must be a more economic version.

    A philosophical, more reflective reason for doing theory is our love of patterns. We are pattern junkies. In our effort to find harmony and conceptually beautiful ways to understand everything at the deepest possible level we do science or create art. Neither of them directly enhances or contributes to our survival probability, but the least important things for our survival are the very things that make us human. For me, art and science are equally important; after a hard day of research I listen to music and find these patterns very relaxing because they are beautiful, and also because I don’t have to actively scrutinise them.

    P.C. Is it possible that at some point we will have answered all the fundamental questions and the scientific endeavours will come to an end?

    S.D. Humans tend to be quite dismissive of the things they learn. There is a famous saying: “Yesterday’s sensation, today’s calibration, tomorrow’s background”. We get bored, and want to move immediately to the next level. For many decades, if not centuries, we have been trying to find a model that explains all the interactions to any conceivable energy that we have experimented with so far. We came up with the Standard Model that may describe almost all known phenomena, but now we want to effectively build a meta-theory that explains the theory itself. However, I am sure that even if we find this meta-theory, we will still come up with more questions. That’s what makes us, as humans, a progressive species: we get excited, we investigate, we discover, and then we get bored and want to get excited again by moving to the next questions.

    P.C. Do you think that the social context is still in favour of researching particle physics and fundamental questions?

    S.D. I think that the public is very interested in fundamental physics. Physics enrollment at universities like Stanford has been going steadily up for the last 15 years at undergraduate and graduate level, despite the fact that there are more competing disciplines, such as biology and information technology. I have also received a lot of positive feedback from the movie Particle Fever.

    However, when the producer approached me ten years ago and told me that he wanted to make a movie about particle physics, I said: “That sounds boring. Who cares about particle physics? You are wasting your time”. “It’s not about particle physics,” he replied, “it’s about particle physicists”. I said: “This is even worse. They are the plainest people on the planet”. I was proven blatantly wrong. And it’s not just Particle Fever. This year there are several movies about science: Gravity, Interstellar, the Imitation Game that is about Alan Turing, and The Theory of Everything about Steven Hawking.

    I think that part of the reason why many more young people don’t go into physics in general and particle physics in particular is that we are not very good at communicating the sense of excitement or even the practical importance of our discoveries to the public. If more effort is put in that direction, it will do wonders to attract bright young people.

    Outreach is a little easier for astrophysicists and cosmologists, because people can lift their eyes to the sky and see what they talk about. Our job, however, is to explain that big entities consist of small parts, which, in a sense, are more fundamental.

    In my experience, two books that I read when I was twelve played a big role in my choosing to be a physicist. One was by Einstein and Infeld and the other was a biography of Einstein by Philipp Frank.

    P.C. Maybe this is the right time to ask you, as a teacher now, what’s your main advice to your students?

    S.D. Enjoy yourself and work on the biggest problems that you can tackle.

    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

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    CERN LHCb New

    LHC

    CERN LHC New
    CERN LHC Grand Tunnel

    LHC particles

    Quantum Diaries

     
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