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  • richardmitnick 5:10 pm on May 26, 2017 Permalink | Reply
    Tags: , , Dark photons, Dark sector particles, First results from search for a dark light, Jlab CEBAF accelerator, Symmetry Magazine   

    From Symmetry: “First results from search for a dark light” 

    Symmetry Mag


    Manuel Gnida

    Chris Smith, SLAC National Accelerator Laboratory

    The Heavy Photon Search at Jefferson Lab is looking for a hypothetical particle from a hidden “dark sector.”

    JLab campus


    In 2015, a group of researchers installed a particle detector just half of a millimeter away from an extremely powerful electron beam. The detector could either start them on a new search for a hidden world of particles and forces called the “dark sector”—or its sensitive parts could burn up in the beam.

    Earlier this month, scientists presented the results from that very first test run at the Heavy Photon Search collaboration meeting at the US Department of Energy’s Thomas Jefferson National Accelerator Facility. To the scientists’ delight, the experiment is working flawlessly.

    Dark sector particles could be the long-sought components of dark matter, the mysterious form of matter thought to be five times more abundant in the universe than regular matter. To be specific, HPS is looking for a dark-sector version of the photon, the elementary “particle of light” that carries the fundamental electromagnetic force in the Standard Model of particle physics.

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

    Analogously, the dark photon would be the carrier of a force between dark-sector particles. But unlike the regular photon, the dark photon would have mass. That’s why it’s also called the heavy photon.

    To search for dark photons, the HPS experiment uses a very intense, nearly continuous beam of highly energetic electrons from Jefferson Lab’s CEBAF accelerator. When slammed into a tungsten target, the electrons radiate energy that could potentially produce the mystery particles. Dark photons are believed to quickly decay into pairs of electrons and their antiparticles, positrons, which leave tracks in the HPS detector.

    JLab CEBAF accelerator

    “Dark photons would show up as an anomaly in our data—a very narrow bump on a smooth background from other processes that produce electron-positron pairs,” says Omar Moreno from SLAC National Accelerator Laboratory, who led the analysis of the first data and presented the results at the collaboration meeting.

    The challenge is that, due to the large beam energy, the decay products are compressed very narrowly in beam direction. To catch them, the detector must be very close to the electron beam. But not too close—the smallest beam movements could make the beam swerve into the detector. Even if the beam doesn’t directly hit the HPS apparatus, electrons interacting in the target can scatter into the detector and cause unwanted signals.

    The HPS team implemented a number of precautions to make sure their detector could handle the potentially destructive beam conditions. They installed and carefully aligned a system to intercept any large beam motions, made the detector’s support structure movable to bring the detector close to the beam and measure the exact beam position, and installed a feedback system that would shut the beam down if its motions were too large. They also placed their whole setup in vacuum because interactions of the beam with gas molecules would create too much background. Finally, they cooled the detector to negative 30 degrees Fahrenheit to reduce the effects of radiation damage. These measures allowed the team to operate their experiment so close to the beam.

    “That’s maybe as close as anyone has ever come to such a particle beam,” says John Jaros, head of the HPS group at SLAC, which built the innermost part of the HPS detector, the Silicon Vertex Tracker. “So, it was fairly exciting when we gradually decreased the distance between the detector and the beam for the first time and saw that everything worked as planned. A large part of that success lies with the beautiful beams Jefferson Lab provided.”

    SLAC’s Mathew Graham, who oversees the HPS analysis group, says, “In addition to figuring out if we can actually do the experiment, the first run also helped us understand the background signals in the experiment and develop the data analysis tools we need for our search for dark photons.”

    So far, the team has seen no signs of dark photons. But to be fair, the data they analyzed came from just 1.7 days of accumulated running time. HPS collects data in short spurts when the CLAS experiment, which studies protons and neutrons using the same beam line, is not in use.

    A second part of the analysis is still ongoing: The researchers are also closely inspecting the exact location, or vertex, from which an electron-positron pair emerges.

    “If a dark photon lives long enough, it might make it out of the tungsten target where it was produced and travel some distance through the detector before it decays into an electron-positron pair,” Moreno says. The detector was specifically designed to observe such a signal.

    Jefferson Lab has approved the HPS project for a total of 180 days of experimental time. Slowly but surely, HPS scientists are finding chances to use it.

    See the full article here .

    Please help promote STEM in your local schools.

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    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 3:50 pm on May 16, 2017 Permalink | Reply
    Tags: , Blind studies, , , , , , , , Symmetry Magazine   

    From Symmetry: “The facts and nothing but the facts” 

    Symmetry Mag


    Artwork by Corinne Mucha

    Manuel Gnida

    At a recent workshop on blind analysis, researchers discussed how to keep their expectations out of their results.

    Scientific experiments are designed to determine facts about our world. But in complicated analyses, there’s a risk that researchers will unintentionally skew their results to match what they were expecting to find. To reduce or eliminate this potential bias, scientists apply a method known as “blind analysis.”

    Blind studies are probably best known from their use in clinical drug trials, in which patients are kept in the dark about—or blind to—whether they’re receiving an actual drug or a placebo. This approach helps researchers judge whether their results stem from the treatment itself or from the patients’ belief that they are receiving it.

    Particle physicists and astrophysicists do blind studies, too. The approach is particularly valuable when scientists search for extremely small effects hidden among background noise that point to the existence of something new, not accounted for in the current model. Examples include the much-publicized discoveries of the Higgs boson by experiments at CERN’s Large Hadron Collider and of gravitational waves by the Advanced LIGO detector.


    CERN/LHC Map

    CERN LHC Tunnel

    CERN LHC particles

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    “Scientific analyses are iterative processes, in which we make a series of small adjustments to theoretical models until the models accurately describe the experimental data,” says Elisabeth Krause, a postdoc at the Kavli Institute for Particle Astrophysics and Cosmology, which is jointly operated by Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory. “At each step of an analysis, there is the danger that prior knowledge guides the way we make adjustments. Blind analyses help us make independent and better decisions.”

    Krause was the main organizer of a recent workshop at KIPAC that looked into how blind analyses could be incorporated into next-generation astronomical surveys that aim to determine more precisely than ever what the universe is made of and how its components have driven cosmic evolution.

    Black boxes and salt

    One outcome of the workshop was a finding that there is no one-size-fits-all approach, says KIPAC postdoc Kyle Story, one of the event organizers. “Blind analyses need to be designed individually for each experiment.”

    The way the blinding is done needs to leave researchers with enough information to allow a meaningful analysis, and it depends on the type of data coming out of a specific experiment.

    A common approach is to base the analysis on only some of the data, excluding the part in which an anomaly is thought to be hiding. The excluded data is said to be in a “black box” or “hidden signal box.”

    Take the search for the Higgs boson. Using data collected with the Large Hadron Collider until the end of 2011, researchers saw hints of a bump as a potential sign of a new particle with a mass of about 125 gigaelectronvolts. So when they looked at new data, they deliberately quarantined the mass range around this bump and focused on the remaining data instead.

    They used that data to make sure they were working with a sufficiently accurate model. Then they “opened the box” and applied that same model to the untouched region. The bump turned out to be the long-sought Higgs particle.

    That worked well for the Higgs researchers. However, as scientists involved with the Large Underground Xenon experiment reported at the workshop, the “black box” method of blind analysis can cause problems if the data you’re expressly not looking at contains rare events crucial to figuring out your model in the first place.

    LUX has recently completed one of the world’s most sensitive searches for WIMPs—hypothetical particles of dark matter, an invisible form of matter that is five times more prevalent than regular matter.

    LUX/Dark matter experiment at SURF

    LUX scientists have done a lot of work to guard LUX against background particles—building the detector in a cleanroom, filling it with thoroughly purified liquid, surrounding it with shielding and installing it under a mile of rock. But a few stray particles make it through nonetheless, and the scientists need to look at all of their data to find and eliminate them.

    For that reason, LUX researchers chose a different blinding approach for their analyses. Instead of using a “black box,” they use a process called “salting.”

    LUX scientists not involved in the most recent LUX analysis added fake events to the data—simulated signals that just look like real ones. Just like the patients in a blind drug trial, the LUX scientists didn’t know whether they were analyzing real or placebo data. Once they completed their analysis, the scientists that did the “salting” revealed which events were false.

    A similar technique was used by LIGO scientists, who eventually made the first detection of extremely tiny ripples in space-time called gravitational waves.

    High-stakes astronomical surveys

    The Blind Analysis workshop at KIPAC focused on future sky surveys that will make unprecedented measurements of dark energy and the Cosmic Microwave Background—observations that will help cosmologists better understand the evolution of our universe.

    CMB per ESA/Planck


    Dark energy is thought to be a force that is causing the universe to expand faster and faster as time goes by. The CMB is a faint microwave glow spread out over the entire sky. It is the oldest light in the universe, left over from the time the cosmos was only 380,000 years old.

    To shed light on the mysterious properties of dark energy, the Dark Energy Science Collaboration is preparing to use data from the Large Synoptic Survey Telescope, which is under construction in Chile. With its unique 3.2-gigapixel camera, LSST will image billions of galaxies, the distribution of which is thought to be strongly influenced by dark energy.

    Dark Energy Camera [DECam], built at FNAL

    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam

    LSST Camera, built at SLAC

    LSST telescope, currently under construction at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    “Blinding will help us look at the properties of galaxies picked for this analysis independent of the well-known cosmological implications of preceding studies,” DESC member Krause says. One way the collaboration plans on blinding its members to this prior knowledge is to distort the images of galaxies before they enter the analysis pipeline.

    Not everyone in the scientific community is convinced that blinding is necessary. Blind analyses are more complicated to design than non-blind analyses and take more time to complete. Some scientists participating in blind analyses inevitably spend time looking at fake data, which can feel like a waste.

    Yet others strongly advocate for going blind. KIPAC researcher Aaron Roodman, a particle-physicist-turned-astrophysicist, has been using blinding methods for the past 20 years.

    “Blind analyses have already become pretty standard in the particle physics world,” he says. “They’ll be also crucial for taking bias out of next-generation cosmological surveys, particularly when the stakes are high. We’ll only build one LSST, for example, to provide us with unprecedented views of the sky.”

    See the full article here .

    Please help promote STEM in your local schools.

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    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 12:31 pm on May 9, 2017 Permalink | Reply
    Tags: , , , Book "We Have No Idea", , , , , Symmetry Magazine, Understanding the unknown universe   

    From Symmetry: “Understanding the unknown universe” 

    Symmetry Mag


    Diana Kwon

    The authors of We Have No Idea remind us that there are still many unsolved mysteries in science.


    What is dark energy? Why aren’t we made of antimatter? How many dimensions are there?

    These are a few of the many unanswered questions that Jorge Cham, creator of the online comic Piled Higher and Deeper, and Daniel Whiteson, an experimental particle physicist at the University of California, Irvine, explain in their new book, We Have No Idea. In the process, they remind readers of one key point: When it comes to our universe, there’s a lot we still don’t know.

    The duo started working together in 2008 after Whiteson reached out to Cham, asking if he’d be willing to help create physics cartoons. “I always thought physics was well connected to the way comics work,” Whiteson says. “Because, what’s a Feynman diagram but a little cartoon of particles hitting each other?” (Feynman diagrams are pictures commonly used in particle physics papers that represent the interactions of subatomic particles.)

    A Feynman Diagram such as the one shown above is a succinct way of summarising a mathematical calculation. However, even though it looks like a ‘cartoon’ representation of the physics, it does not describe the physical process. https://protonsforbreakfast.wordpress.com/2014/04/13/feynman-diagrams-are-maths-not-physics/

    Before working on this book, the pair made a handful of popular YouTube videos on topics like dark matter, extra dimensions and the Higgs boson. Many of these subjects are also covered in We Have No Idea.

    One of the main motivators of this latest project was to address a “certain apathy toward science,” Cham says. “I think we both came into it having this feeling that the general public either thinks scientists have everything figured out, or they don’t really understand what scientists are doing.” [the main reason for this blog is that the press does not write about science.]

    To get at this issue, the pair focused on topics that even someone without a science background could find compelling. “You don’t need 10 years of physics background to know [that] questions about how the universe started or what it’s made of are interesting,” Whiteson says. “We tried to find questions that were gut-level approachable.”

    CMB per ESA/Planck


    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Another key theme of the book, the authors say, is the line between what science can and cannot tell us. While some of the possible solutions to the universe’s mysteries have testable predictions, others (such as string theory) currently do not. “We wanted questions that were accessible yet answerable,” says Whiteson. “We wanted to show people that there were deep, basic, simple questions that we all had, but that the answers were out there.”

    Many scientists are hard at work trying to fill the gaping holes in our knowledge about the universe. Particle physicists, for example, are exploring a number of these questions, such as those about the nature of antimatter and mass.

    Artwork by Jorge Cham

    Some lines of inquiry have brought different research communities together. Dark matter searches, for example, were primarily the realm of cosmologists, who probe large-scale structures of the universe. However, as the focus shifted to finding out what particle—or particles—dark matter was made of, this area of study started to attract astrophysicists as well.

    Why are people trying to answer these questions? “I think science is an expression of humanity and our curiosity to know the answers to basic questions we ask ourselves: Who are we? Why are we here? How does the world work?” Whiteson says. “On the other hand, questions like these lead to understanding, and understanding leads to being able to have greater power over the environment to solve our problems.

    In the very last chapter of the book, the authors explain the idea of a “testable universe,” or the parts of the universe that fall within the bounds of science. In the Stone Ages, when humans had very few tools at their disposal, the testable universe was very small. But it increased as people built telescopes, satellites and particle colliders, and it continues to expand with ongoing advances in science and technology. “That’s the exciting thing,” Cham says. “Our ability to answer these questions is growing.”

    Some mysteries of the universe still live in the realm of philosophy. But tomorrow, next year or a thousand years from now, a scientist may come along and devise an experiment that will be able to find the answers.

    “We’re in a special place in history when most of the world seems explained,” Whiteson says. Thousands of years ago, basic questions, such as why fire burns or where rain comes from, were still largely a mystery. “These days, all those mysteries seem answered, but the truth is, there’s a lot of mysteries left. [If] you want to make a massive imprint on human intellectual history, there’s plenty of room for that.”

    See the full article here .

    Please help promote STEM in your local schools.

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    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 8:57 pm on May 5, 2017 Permalink | Reply
    Tags: , , , Is this the only universe?, , Symmetry Magazine   

    From Symmetry: “Is this the only universe?” 

    Symmetry Mag


    07/28/15 [Never saw this before in social media.]
    Laura Dattaro

    No image credit

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Human history has been a journey toward insignificance.

    As we’ve gained more knowledge, we’ve had our planet downgraded from the center of the universe to a chunk of rock orbiting an average star in a galaxy that is one among billions.

    Milky Way NASA/JPL-Caltech /ESO R. Hurt

    So it only makes sense that many physicists now believe that even our universe might be just a small piece of a greater whole. In fact, there may be infinitely many universes, bubbling into existence and growing exponentially. It’s a theory known as the multiverse.

    Multiverse. Image credit: public domain, retrieved from https://pixabay.com/

    One of the best pieces of evidence for the multiverse was first discovered in 1998, when physicists realized that the universe was expanding at ever increasing speed. They dubbed the force behind this acceleration dark energy.

    The universe has been expanding since the Big Bang kickstarted the growth about 13.8 billion years.

    The value of its energy density, also known as the cosmological constant [Λ], is bizarrely tiny: 120 orders of magnitude smaller than theory says it should be.

    For decades, physicists have sought an explanation for this disparity. The best one they’ve come up with so far, says Yasunori Nomura, a theoretical physicist at the University of California, Berkeley, is that it’s only small in our universe. There may be other universes where the number takes a different value, and it is only here that the rate of expansion is just right to form galaxies and stars and planets where people like us can observe it. “Only if this vacuum energy stayed to a very special value will we exist,” Nomura says. “There are no good other theories to understand why we observe this specific value.”

    For further evidence of a multiverse, just look to string theory, which posits that the fundamental laws of physics have their own phases, just like matter can exist as a solid, liquid or gas. If that’s correct, there should be other universes where the laws are in different phases from our own—which would affect seemingly fundamental values that we observe here in our universe, like the cosmological constant. “In that situation you’ll have a patchwork of regions, some in this phase, some in others,” says Matthew Kleban, a theoretical physicist at New York University.

    These regions could take the form of bubbles, with new universes popping into existence all the time. One of these bubbles could collide with our own, leaving traces that, if discovered, would prove other universes are out there. We haven’t seen one of these collisions yet, but physicists are hopeful that we might in the not so distant future.

    If we can’t find evidence of a collision, Kleban says, it may be possible to experimentally induce a phase change—an ultra-high-energy version of coaxing water into vapor by boiling it on the stove. You could effectively prove our universe is not the only one if you could produce phase-transitioned energy, though you would run the risk of it expanding out of control and destroying the Earth. “If those phases do exist—if they can be brought into being by some kind of experiment—then they certainly exist somewhere in the universe,” Kleban says.

    No one is yet trying to do this.

    There might be a (relatively) simpler way. Einstein’s general theory of relativity implies that our universe may have a “shape.” It could be either positively curved, like a sphere, or negatively curved, like a saddle. A negatively curved universe would be strong evidence of a multiverse, Nomura says. And a positively curved universe would show that there’s something wrong with our current theory of the multiverse, while not necessarily proving there’s only one. (Proving that is a next-to-impossible task. If there are other universes out there that don’t interact with ours in any sense, we can’t prove whether they exist.)

    In recent years, physicists have discovered that the universe appears almost entirely flat. But there’s still a possibility that it’s slightly curved in one direction or the other, and Nomura predicts that within the next few decades, measurements of the universe’s shape could be precise enough to detect a slight curvature. That would give physicists new evidence about the nature of the multiverse. “In fact, this evidence will be reasonably strong since we do not know any other theory which may naturally lead to a nonzero curvature at a level observable in the universe,” Nomura says.

    If the curvature turned out to be positive, theorists would face some very difficult questions. They would still be left without an explanation for why the expansion rate of the universe is what it is. The phases within string theory would also need re-examining. “We will face difficult problems,” Nomura says. “Our theory of dark energy is gone if it’s the wrong curvature.”

    But with the right curvature, a curved universe could reframe how physicists look at values that, at present, appear to be fundamental. If there were different universes with different phases of laws, we might not need to seek fundamental explanations for some of the properties our universe exhibits.

    And it would, of course, mean we are tinier still than we ever imagined. “It’s like another step in this kind of existential crisis,” Kleban says. “It would have a huge impact on people’s imaginations.”

    See the full article here .

    Please help promote STEM in your local schools.

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    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 3:31 pm on May 5, 2017 Permalink | Reply
    Tags: 1000 meters below - the worlds best underground labs, , Symmetry Magazine   

    From Symmetry: “1,000 meters below” a Huge and Important Article- Do Not Skip This 

    Symmetry Mag


    05/31/16 [Somehow, I missed this.]
    Rashmi Shivni

    Surf-Dune/LBNF Caverns at Sanford

    Not sure of the depth, but you get the point.

    Meet the world’s deepest underground physics facilities.

    A constant shower of energetic subatomic particles rains down on Earth’s surface. Born from cosmic ray interactions in the upper atmosphere, this invisible drizzle creates noisy background radiation that obscures the signatures of new particles or forces that scientists seek. The solution is to move experiments under the best natural umbrella we have: the Earth’s crust.

    Underground facilities, while difficult to build and access, are ideal hubs for observing rare particle interactions. The rock overhead shields experiments from the pesky particle precipitation, preventing things like muons from interfering. For the last few decades, underground physics facilities have laid claim to some of the world’s largest, most complex detection experiments, contributing to important physics discoveries.

    “In the early 1960s, researchers at the Kolar Gold Fields in India and the East Rand Gold Mine in South Africa realized if they go deep enough underground, it might be possible to clearly detect high-energy particles from atmospheric cosmic ray collisions,” says Henry Sobel, a co-US-spokesperson on the Super-Kamiokande experiment at the Kamioka Observatory.

    Super-Kamiokande experiment Japan

    “Both groups reported the first observation of atmospheric neutrinos at various depths underground.”

    Even with entire facilities sitting below the surface, extremely sensitive detectors often require additional shielding against stray particles and the small amount of radiation from the rock and equipment. One example is the Sanford Underground Research Facility’s Large Underground Xenon (LUX) experiment, which seeks dark matter particles called WIMPs, or weakly interacting massive particles.

    LUX/Dark matter experiment at SURF

    Lux Zeplin project at SURF

    SURF building in Lead SD USA

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

    “Going underground eliminates most of the radioactivity, but not all of it, so we used a 72,000-gallon water shield to keep neutrons and gamma rays out of the LUX experiment,” says Harry Nelson, a LUX researcher and spokesperson for the upcoming LUX-Zeplin experiment at Sanford Lab.

    Scientists at underground facilities around the world—and their creative colleagues closer to the surface—maintain different experiments working toward a common goal: answering questions about the nature of matter and energy. Learn more about the facilities 1000 meters or more below the surface that are digging deep into the secrets of the universe.

    Kamioka Observatory

    KamLAND at the Kamioka Observatory in Japan

    KamLAND at the Kamioka Observatory in Japan

    1000 meters below, est. 1983

    Previously known as the Kamioka Underground Observatory, the facility dwells in the Mozumi Mine in Hida, Gifu Prefecture, Japan. Operational or former mines actually make great homes for underground facilities because it is cost-effective to use existing giant holes inside mountains or the earth rather than dig new ones.

    Kamioka’s original focus was on understanding the stability of matter through a search for the spontaneous decay of protons using an experiment called Kamiokande. Since neutrinos are a major background to the search for proton decay, the study of neutrinos also became a major effort for the observatory.

    Now known as the Kamioka Observatory, the facility detects neutrinos coming from supernovae, the sun, our atmosphere and accelerators. In 2015, Takaaki Kajita was awarded the Nobel Prize in physics for the discovery of atmospheric neutrino oscillation by the Super-Kamiokande experiment. The Nobel Prize is shared with the Sudbury Neutrino Observatory in Canada.

    SNOLAB, Sudbury, Ontario, Canada.

    LBNL SuperCDMS, at SNOLAB (Vale Inco Mine, Sudbury, Canada)

    LBL Super CDMS, at SNOLAB (Vale Inco Mine, Sudbury, Canada)

    Stawell Underground Physics Laboratory
    1000 meters below, under construction


    SUPL is under construction at the active Stawell Gold Mine in Victoria, Australia. The facility will work in close collaboration with the Gran Sasso National Laboratory in Italy, which made significant strides in dark matter research through a possible detection of WIMPs. SUPL will see whether the amount of dark matter in certain galaxies changes depending on Earth’s position.


    INFN Gran Sasso ICARUS, since moved to FNAL

    DAMA II at Gran Sasso

    Because Australia is in the Southern Hemisphere and has opposite seasons to Italy, this seasonal dark matter experiment will also test Italy’s results to learn more about WIMPs and dark matter. There are two proposed dark matter experiments for SUPL: SABRE (Sodium-iodide with Active Background REjection) and DRIFT-CYGNUS (Directional Recoil Identification From Tracks – CosmoloGY with NUclear recoilS).

    Boulby Underground Laboratory
    1100 meters below, est. 1998.


    Inside the operational Boulby Potash and Salt Mine on the northeast coast of England sits the Boulby Lab. It is a multidisciplinary, deep underground science facility operated by the UK’s Science and Technology Facilities Council. The depth and the support infrastructure make the facility well-suited for traditional low-background underground studies such as dark matter searches and cosmic ray experiments. Scientists also study a wide range of sciences beyond physics, for example geology and geophysics, environmental and climate studies, life in extreme environments on Earth, and the development of rover instrumentation for exploration of life beyond Earth.

    The dark matter search currently underway at Boulby is DRIFT-II – a directional dark matter search detector. The lab previously hosted the ZEPLIN-II and III experiments, predecessors to the upcoming LUX-ZEPLIN experiment at Sanford Lab. Boulby still supports the LZ experiment with ultralow-background material activity measurements, which is important to all sensitive dark matter and rare-event studies.

    India-based Neutrino Observatory
    1200 meters below, proposed

    INO, a collaboration of about 25 national institutes and universities hosted by the Tata Institute of Fundamental Research, will primarily be an underground facility for non-accelerator-based high-energy physics. The observatory will focus its study on atmospheric muon neutrinos using a 50-kiloton iron calorimeter to measure certain characteristics of the elusive particles.

    INO will also expand into a more general science facility and host studies in geological, biological and hydrological research. Construction of the INO underground observatory in Pottipuram, Tamil Nadu, India is awaiting approvals by the state government.

    Gran Sasso National Laboratory [Shown above on first reference]
    1400 meters below, est. 1987

    The Gran Sasso National Laboratory in Italy is the largest underground laboratory in the world. It is a high-energy physics lab that conducts many long-term neutrino, dark matter and nuclear astrophysical experiments.

    The lab’s OPERA experiment is especially noteworthy for detecting the first tau neutrino candidates that emerged (through oscillation) from a muon neutrino beam sent by CERN in 2010.


    From 2012 to 2015, the experiment at Gran Sasso subsequently announced the detection of the second, third, fourth and fifth tau neutrinos, confirming their initial result.

    Gran Sasso also collaborates with the Department of Energy’s Fermi National Accelerator Laboratory [FNAL] on a short-distance neutrino program. After it is refurbished at CERN, the ICARUS experiment [shown above on first reference] from Gran Sasso will join two other experiments at Fermilab to search for a fourth proposed kind of neutrino, the sterile neutrino.

    Centre for Underground Physics in Pyhäsalmi
    1440 meters below, est. 1997

    The University of Oulu in Finland operates CUPP in Europe’s deepest metal mine—the Pyhäsalmi Mine. As the mine prepares to close by the end of this decade, the local community established Callio Lab (CLab) to rent out space to science and industrial operators, CUPP being one of them. The main level, at 1420 meters, houses all of the equipment, offices and restaurants. It also houses the world’s deepest sauna.

    The facility’s main experiment is EMMA, the Experiment with MultiMuon Array, in Lab 1 at 75 meters. EMMA is used to study cosmic rays and high-energy muons that pass through the Earth to better understand atmospheric and cosmic particle interactions. CUPP also conducts some low-background muon flux measurements and radiocarbon research for future liquid scintillators in Lab 2 at 1430 meters.

    Sanford Underground Research Facility
    1480 meters below, est. 2011

    Sanford Lab is the deepest underground physics lab in the United States and sits in the former Homestake Gold Mine in the Black Hills of South Dakota. It was the site of Ray Davis’ solar neutrino experiment, which used dry cleaning fluid to count neutrinos from the sun. The experiment found only one-third of the neutrinos expected, the result known as the solar neutrino problem. In 1998, SNO and Kamioka discovered neutrino oscillations, which proved that neutrinos were changing type as they traveled. Davis won the Nobel Prize in physics in 2002.

    The facility now houses the LUX experiment [shown above on first reference] (looking for dark matter), Majorana Demonstrator (researching the properties of neutrinos), and geological, engineering and biological studies. Sanford Lab will also host the Deep Underground Neutrino Experiment, which will use detectors filled with 70,000 tons of liquid argon to study neutrinos sent from Fermilab, 800 miles away.

    U Washington Majorana Demonstrator Experiment at SURF

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

    FNAL DUNE Argon tank at SURF

    CERN Proto DUNE Maximillian Brice

    FNAL/DUNE Near Site Layout

    Modane Underground Laboratory
    1700 meters below, est. 1982


    Located in Modane, France, and situated in the middle of the Frejús Road Tunnel, the multidisciplinary lab hosts experiments in particle, nuclear and astroparticle physics, environmental sciences, biology and nano- and microelectronics.

    Headed by the French National Center for Scientific Research and the Genoble-Alpes University, Modane Lab’s main fundamental physics activities include SuperNEMO and EDELWEISS, which study neutrino physics and dark matter detection, respectively.



    The lab also hosts international experiments with the Joint Institute for Nuclear Research in Dubna, Russia, and the Czech Technical University in Prague, Czech Republic.

    Baksan Neutrino Observatory
    1750 meters below, est. 1973

    Baksan Neutrino Observatory

    Baksan The Underground Scintillation Telescope

    Hidden beneath the Caucasus Mountains and next to the Baksan River, BNO began working as one of the first underground particle physics observatories in the then Soviet Union. Like other underground facilities, BNO wanted to reduce the amount of background radiation as much as possible. The lab’s location is not only underground but also far from nuclear power plants—another source of background noise for experiments.

    BNO’s current neutrino experiments are the Soviet-American Gallium Experiment (SAGE), the Baksan Underground Scintillation Telescope (BUST) and the upcoming Baksan Experiment on Sterile Transitions (BEST). There is also a new search for hypothesized particles called axions, candidates for dark matter.

    Agua Negra Deep Experiment Site
    1750 meters below, proposed


    Situated in the mountains on the border of Chile and Argentina, ANDES will study neutrinos and dark matter, as well as plate tectonics, biology, nuclear astrophysics and the environment. Along with SUPL, it is one of two proposed deep underground labs in the Southern Hemisphere.

    ANDES is an international laboratory, not just a host for international experiments. It will become home to a large neutrino detector and aims to detect supernovae neutrinos and geoneutrinos, complementing results of the Northern Hemisphere labs and experiments. This location is ideal as the site is far from nuclear facilities and extremely deep in the mountains, both of which help reduce background noise.

    SNOLAB [shown above on first reference]
    2070 meters below, est. 2009

    SNOLAB is the deepest physics facility in North America and operates in a working nickel mine in Ontario, Canada. The entire 5000m2 facility is a class 2000 cleanroom with fewer than 2000 particles per cubic foot. Everyone who enters the lab must shower on the way in and put on a clean set of special cleanroom clothes.

    SNOLAB conducts highly sensitive experiments for research on dark matter and neutrinos. Among them are DEAP-3600, PICO, HALO, MiniCLEAN and SNO+. Scientists also plan to install the next generation of a cryogenic dark matter search, SuperCDMS, in the lab once testing is complete.






    Late last year, Arthur McDonald was awarded the Nobel Prize in physics for the discovery of neutrino oscillation made in 1998 at the Sudbury Neutrino Observatory, the predecessor of SNOLAB. The Nobel Prize is shared with the Kamioka Observatory in Japan for their Super-K neutrino experiment.

    China Jinping Underground Laboratory
    2400 meters below, est. 2010

    China Jinping Underground Laboratory

    CJPL is the deepest physics facility in the world, tucked inside the Jinping Mountain in the Sichuan province in southwest China. The site is ideal for its low cosmic-ray muon flux, which means the facility has far less noise from background radiation than many other underground facilities. And because the facility is built under a mountain, there is horizontal access (for things like vehicles) rather than vertical access (through a mine shaft).

    Two experiments housed at the facility are trying to directly detect dark matter: the China Dark Matter Experiment (CDEX) and PandaX. CJPL will also observe neutrinos from different sources, such as the sun, Earth, atmosphere, supernova bursts and potentially dark matter annihilations, in hopes of better understanding the elusive particles’ properties. In the coming months, an astronuclear physics study and a one-ton prototype of a neutrino detector will move into CJPL-II.

    China’s PandaX Detector Joins the Search for Dark Matter and WIMPs

    China Dark Matter Experiment (CDEX)

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 1:39 pm on May 4, 2017 Permalink | Reply
    Tags: , , , Symmetry Magazine   

    From Symmetry: “Sterile neutrino search hits roadblock at reactors” 

    Symmetry Mag


    Kathryn Jepsen


    A new result from the Daya Bay collaboration reveals both limitations and strengths of experiments studying antineutrinos at nuclear reactors.

    As nuclear reactors burn through fuel, they produce a steady flow of particles called neutrinos. Neutrinos interact so rarely with other matter that they can flow past the steel and concrete of a power plant’s containment structures and keep on moving through anything else that gets in their way.

    Physicists interested in studying these wandering particles have taken advantage of this fact by installing neutrino detectors nearby. A recent result using some of these detectors demonstrated both their limitations and strengths.

    The reactor antineutrino anomaly

    In 2011, a group of theorists noticed that several reactor-based neutrino experiments had been publishing the same, surprising result: They weren’t detecting as many neutrinos as they thought they would.

    Or rather, to be technically correct, they weren’t seeing as many antineutrinos as they thought they would; nuclear reactors actually produce the antimatter partners of the elusive particles. About 6 percent of the expected antineutrinos just weren’t showing up. They called it “the reactor antineutrino anomaly.”

    The case of the missing neutrinos was a familiar one. In the 1960s, the Davis experiment located in Homestake Mine in South Dakota reported a shortage of neutrinos coming from processes in the sun.

    Construction of the Homestake Mine tank. BNL.

    Other experiments confirmed the finding. In 2001, the Sudbury Neutrino Observatory in Ontario demonstrated that the missing neutrinos weren’t missing at all; they had only undergone a bit of a costume change.

    SNOLAB, Sudbury, Ontario, Canada.

    Neutrinos come in three types. Scientists discovered that neutrinos could transform from one type to another. The missing neutrinos had changed into a different type of neutrino that the Davis experiment couldn’t detect.

    Since 2011, scientists have wondered whether the reactor antineutrino anomaly was a sign of an undiscovered type of neutrino, one that was even harder to detect, called a sterile neutrino.

    A new result from the Daya Bay experiment in China not only casts doubt on that theory, it also casts doubt on the idea that scientists understand their model of reactor processes well enough at this time to use it to search for sterile neutrinos.

    The word from Daya Bay

    The Daya Bay experiment studies antineutrinos coming from six nuclear reactors on the southern coast of China, about 35 miles northeast of Hong Kong. The reactors are powered by the fission of uranium. Over time, the amount of uranium inside the reactor decreases while the amount of plutonium increases. The fuel is changed—or cycled—about every 18 months.

    The main goal of the Daya Bay experiment was to look for the rarest of the known neutrino oscillations. It did that, making a groundbreaking discovery after just nine weeks of data-taking.

    But that wasn’t the only goal of the experiment. “We realized right from the beginning that it is important for Daya Bay to address as many interesting physics problems as possible,” says Daya Bay co-spokesperson Kam-Biu Luk of the University of California, Berkeley and the US Department of Energy’s Lawrence Berkeley National Laboratory.

    For this result, Daya Bay scientists took advantage of their enormous collection of antineutrino data to expand their investigation to the reactor antineutrino anomaly.

    Using data from more than 2 million antineutrino interactions and information about when the power plants refreshed the uranium in each reactor, Daya Bay physicists compared the measurements of antineutrinos coming from different parts of the fuel cycle: early ones dominated by uranium through later ones dominated by both uranium and plutonium.

    n theory, the type of fuel producing the antineutrinos should not affect the rate at which they transform into sterile neutrinos. According to Bob Svoboda, chair of the Department of Physics at the University of California, Davis, “a neutrino wouldn’t care how it got made.” But Daya Bay scientists found that the shortage of antineutrinos existed only in processes dominated by uranium.

    Their conclusion is that, once again, the missing neutrinos aren’t actually missing. This time, the problem of the missing antineutrinos seems to stem from our understanding of how uranium burns in nuclear power plants. The predictions for how many antineutrinos the scientists should detect may have been overestimated.

    “Most of the problem appears to come from the uranium-235 model (uranium-235 is a fissile isotope of uranium), not from the neutrinos themselves,” Svoboda says. “We don’t fully understand uranium, so we have to take any anomaly we measured with a grain of salt.”

    This knock against the reactor antineutrino anomaly does not disprove the existence of sterile neutrinos. Other, non-reactor experiments have seen different possible signs of their influence. But it does put a damper on the only evidence of sterile neutrinos to have come from reactor experiments so far.

    Other reactor neutrino experiments, such as NEOS in South Korea and PROSPECT in the United States will fill in some missing details.


    Prospect. BNL

    NEOS scientists directly measured antineutrinos coming from reactors in the Hanbit nuclear power complex using a detector placed about 80 feet away, a distance some scientists believe is optimal for detecting sterile neutrinos should they exist. PROSPECT scientists will make the first precision measurement of antineutrinos coming from a highly enriched uranium core, one that does not produce plutonium as it burns.

    A silver lining

    The Daya Bay result offers the most detailed demonstration yet of scientists’ ability to use neutrino detectors to peer inside running nuclear reactors.

    “As a study of reactors, this is a tour de force,” says theorist Alexander Friedland of SLAC National Accelerator Laboratory. “This is an explicit demonstration that the composition of the reactor fuel has an impact on the neutrinos.”

    Some scientists are interested in monitoring nuclear power plants to find out if nuclear fuel is being diverted to build nuclear weapons.

    “Suppose I declare my reactor produces 100 kilograms of plutonium per year,” says Adam Bernstein of the University of Hawaii and Lawrence Livermore National Laboratory. “Then I operate it in a slightly different way, and at the end of the year I have 120 kilograms.” That 20-kilogram surplus, left unmeasured, could potentially be moved into a weapons program.

    Current monitoring techniques involve checking what goes into a nuclear power plant before the fuel cycle begins and then checking what comes out after it ends. In the meantime, what happens inside is a mystery.

    Neutrino detectors allow scientists to understand what’s going on in a nuclear reactor in real time.

    Scientists have known for decades that neutrino detectors could be useful for nuclear nonproliferation purposes. Scientists studying neutrinos at the Rovno Nuclear Power Plant in Ukraine first demonstrated that neutrino detectors could differentiate between uranium and plutonium fuel.

    Most of the experiments have done this by looking at changes in the aggregate number of antineutrinos coming from a detector. Daya Bay showed that neutrino detectors could track the plutonium inventory in nuclear fuel by studying the energy spectrum of antineutrinos produced.

    “The most likely use of neutrino detectors in the near future is in so-called ‘cooperative agreements,’ where a $20-million-scale neutrino detector is installed in the vicinity of a reactor site as part of a treaty,” Svoboda says. “The site can be monitored very reliably without having to make intrusive inspections that bring up issues of national sovereignty.”

    Luk says he is dubious that the idea will take off, but he agrees that Daya Bay has shown that neutrino detectors can give an incredibly precise report. “This result is the best demonstration so far of using a neutrino detector to probe the heartbeat of a nuclear reactor.”

    See the full article here .

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  • richardmitnick 8:32 pm on May 2, 2017 Permalink | Reply
    Tags: , , , , , Fermi LAT, Mystery glow of Milky Way likely not dark matter, , Symmetry Magazine   

    From Symmetry: “Mystery glow of Milky Way likely not dark matter” 


    Manuel Gnida

    NASA/CXC/University of Massachusetts/D. Wang et al.; Greg Stewart, SLAC National Accelerator Laboratory

    According to the Fermi LAT collaboration, the galaxy’s excessive gamma-ray glow likely comes from pulsars, the remains of collapsed ancient stars.

    NASA/Fermi LAT

    A mysterious gamma-ray glow at the center of the Milky Way is most likely caused by pulsars, the incredibly dense, rapidly spinning cores of collapsed ancient stars that were up to 30 times more massive than the sun.

    That’s the conclusion of a new analysis by an international team of astrophysicists on the Fermi LAT collaboration. The findings cast doubt on previous interpretations of the signal as a potential sign of dark matter, a form of matter that accounts for 85 percent of all matter in the universe but that so far has evaded detection.

    “Our study shows that we don’t need dark matter to understand the gamma-ray emissions of our galaxy,” says Mattia Di Mauro from the Kavli Institute for Particle Astrophysics and Cosmology, a joint institute of Stanford University and the US Department of Energy’s SLAC National Accelerator Laboratory. “Instead, we have identified a population of pulsars in the region around the galactic center, which sheds new light on the formation history of the Milky Way.”

    Di Mauro led the analysis, which looked at the glow with the Large Area Telescope on NASA’s Fermi Gamma-ray Space Telescope, which has been orbiting Earth since 2008. The LAT, a sensitive “eye” for gamma rays, the most energetic form of light, was conceived of and assembled at SLAC, which also hosts its operations center.

    The collaboration’s findings, submitted to The Astrophysical Journal for publication, are available as a preprint.

    A mysterious glow

    Dark matter is one of the biggest mysteries of modern physics. Researchers know that dark matter exists because it bends light from distant galaxies and affects how galaxies rotate. But they don’t know what the substance is made of. Most scientists believe it’s composed of yet-to-be-discovered particles that almost never interact with regular matter other than through gravity, making it very hard to detect them.

    One way scientific instruments might catch a glimpse of dark matter particles is when the particles either decay or collide and destroy each other. “Widely studied theories predict that these processes would produce gamma rays,” says Seth Digel, head of KIPAC’s Fermi group. “We search for this radiation with the LAT in regions of the universe that are rich in dark matter, such as the center of our galaxy.”

    Previous studies have indeed shown that there are more gamma rays coming from the galactic center than expected, fueling some scientific papers and media reports that suggest the signal might hint at long-sought dark matter particles. However, gamma rays are produced in a number of other cosmic processes, which must be ruled out before any conclusion about dark matter can be drawn. This is particularly challenging because the galactic center is extremely complex, and astrophysicists don’t know all the details of what’s going on in that region.

    Most of the Milky Way’s gamma rays originate in gas between the stars that is lit up by cosmic rays, charged particles produced in powerful star explosions called supernovae. This creates a diffuse gamma-ray glow that extends throughout the galaxy. Gamma rays are also produced by supernova remnants, pulsars—collapsed stars that emit “beams” of gamma rays like cosmic lighthouses—and more exotic objects that appear as points of light.

    “Two recent studies by teams in the US and the Netherlands have shown that the gamma-ray excess at the galactic center is speckled, not smooth as we would expect for a dark matter signal,” says KIPAC’s Eric Charles, who contributed to the new analysis. “Those results suggest the speckles may be due to point sources that we can’t see as individual sources with the LAT because the density of gamma-ray sources is very high and the diffuse glow is brightest at the galactic center.”

    Remains of ancient stars

    The new study takes the earlier analyses to the next level, demonstrating that the speckled gamma-ray signal is consistent with pulsars.

    “Considering that about 70 percent of all point sources in the Milky Way are pulsars, they were the most likely candidates,” Di Mauro says. “But we used one of their physical properties to come to our conclusion. Pulsars have very distinct spectra—that is, their emissions vary in a specific way with the energy of the gamma rays they emit. Using the shape of these spectra, we were able to model the glow of the galactic center correctly with a population of about 1,000 pulsars and without introducing processes that involve dark matter particles.”

    The team is now planning follow-up studies with radio telescopes to determine whether the identified sources are emitting their light as a series of brief light pulses—the trademark that gives pulsars their name.

    Discoveries in the halo of stars around the center of the galaxy, the oldest part of the Milky Way, also reveal details about the evolution of our galactic home, just as ancient remains teach archaeologists about human history.

    “Isolated pulsars have a typical lifetime of 10 million years, which is much shorter than the age of the oldest stars near the galactic center,” Charles says. “The fact that we can still see gamma rays from the identified pulsar population today suggests that the pulsars are in binary systems with companion stars, from which they leach energy. This extends the life of the pulsars tremendously.”

    Dark matter remains elusive

    The new results add to other data that are challenging the interpretation of the gamma-ray excess as a dark matter signal.

    “If the signal were due to dark matter, we would expect to see it also at the centers of other galaxies,” Digel says. “The signal should be particularly clear in dwarf galaxies orbiting the Milky Way. These galaxies have very few stars, typically don’t have pulsars and are held together because they have a lot of dark matter. However, we don’t see any significant gamma-ray emissions from them.”

    The researchers believe that a recently discovered strong gamma-ray glow at the center of the Andromeda galaxy, the major galaxy closest to the Milky Way, may also be caused by pulsars rather than dark matter.

    But the last word may not have been spoken. Although the Fermi-LAT team studied a large area of 40 degrees by 40 degrees around the Milky Way’s galactic center (the diameter of the full moon is about half a degree), the extremely high density of sources in the innermost four degrees makes it very difficult to see individual ones and rule out a smooth, dark matter-like gamma-ray distribution, leaving limited room for dark matter signals to hide.

    This work was funded by NASA and the DOE Office of Science, as well as agencies and institutes in France, Italy, Japan and Sweden.

    See the full article here .

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  • richardmitnick 12:23 pm on April 26, 2017 Permalink | Reply
    Tags: , , Blue Sky Research, Symmetry Magazine   

    From Symmetry: “How blue-sky research shapes the future” 

    Symmetry Mag


    Diana Kwon


    While driven by the desire to pursue curiosity, fundamental investigations are the crucial first step to innovation.

    When scientists announced their discovery of gravitational waves in 2016, it made headlines all over the world. The existence of these invisible ripples in space-time had finally been confirmed.

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    It was a momentous feat in basic research, the curiosity-driven search for fundamental knowledge about the universe and the elements within it. Basic (or “blue-sky”) research is distinct from applied research, which is targeted toward developing or advancing technologies to solve a specific problem or to create a new product.

    But the two are deeply connected.

    “Applied research is exploring the continents you know, whereas basic research is setting off in a ship and seeing where you get,” says Frank Wilczek, a theoretical physicist at MIT. “You might just have to return, or sink at sea, or you might discover a whole new continent. So it’s much more long-term, it’s riskier and it doesn’t always pay dividends.”

    When it does, he says, it opens up entirely new possibilities available only to those who set sail into uncharted waters.

    Most of physics—especially particle physics—falls under the umbrella of basic research. In particle physics “we’re asking some of the deepest questions that are accessible by observations about the nature of matter and energy—and ultimately about space and time also, because all of these things are tied together,” says Jim Gates, a theoretical physicist at the University of Maryland.

    CERN/LHC Map

    CERN LHC Tunnel

    LHC at CERN. Basic research in Particle Physics

    Physicists seek answers to questions about the early universe, the nature of dark energy, and theoretical phenomena, such as supersymmetry, string theory and extra dimensions.

    Perhaps one of the most well-known basic researchers was the physicist who predicted the existence of gravitational waves: Albert Einstein.

    Einstein devoted his life to elucidating elementary concepts such as the nature of gravity and the relationship between space and time. According to Wilczek, “it was clear that what drove what he did was not the desire to produce a product, or anything so worldly, but to resolve puzzles and perceived imperfections in our understanding.”

    In addition to advancing our understanding of the world, Einstein’s work led to important technological developments. The Global Positioning System, for instance, would not have been possible without the theories of special and general relativity. A GPS receiver, like the one in your smart phone, determines its location based on timed signals it receives from the nearest four of a collection of GPS satellites orbiting Earth. Because the satellites are moving so quickly while also orbiting at a great distance from the gravitational pull of Earth, they experience time differently from the receiver on Earth’s surface. Thanks to Einstein’s theories, engineers can calculate and correct for this difference.

    There’s a long history of serendipitous output from basic research. For example, in 1989 at CERN European research center, computer scientist Tim Berners-Lee was looking for a way to facilitate information-sharing between researchers. He invented the World Wide Web.

    While investigating the properties of nuclei within a magnetic field at Columbia University in the 1930s, physicist Isidor Isaac Rabi discovered the basic principles of nuclear magnetic resonance. These principles eventually formed the basis of Magnetic Resonance Imaging, MRI.

    It would be another 50 years before MRI machines were widely used—again with the help of basic research. MRI machines require big, superconducting magnets to function. Luckily, around the same time that Rabi’s discovery was being investigated for medical imaging, scientists and engineers at the US Department of Energy’s Fermi National Accelerator Laboratory began building the Tevatron particle accelerator to enable research into the fundamental nature of particles, a task that called for huge amounts of superconducting wire.

    FNAL/Tevatron map

    FNAL/Tevatron CDF detector

    FNAL/Tevatron DZero detector

    “We were the first large, demanding customer for superconducting cable,” says Chris Quigg, a theoretical physicist at Fermilab. “We were spending a lot of money to get the performance that we needed.” The Tevatron created a commercial market for superconducting wire, making it practical for companies to build MRI machines on a large scale for places like hospitals.

    Doctors now use MRI to produce detailed images of the insides of the human body, helpful tools in diagnosing and treating a variety of medical complications, including cancer, heart problems, and diseases in organs such as the liver, pancreas and bowels.

    Another tool of particle physics, the particle detector, has also been adopted for uses in various industries. In the 1980s, for example, particle physicists developed technology precise enough to detect a single photon. Today doctors use this same technology to detect tumors, heart disease and central nervous system disorders. They do this by conducting positron emission tomography scans, or PET scans. Before undergoing a PET scan, the patient is given a dye containing radioactive tracers, either through an injection or by ingesting or inhaling. The tracers emit antimatter particles, which interact with matter particles and release photons, which are picked up by the PET scanner to create a picture detailed enough to reveal problems at the cellular level.

    As Gates says, “a lot of the devices and concepts that you see in science fiction stories will never come into existence unless we pursue the concept of basic research. You’re not going to be able to construct starships unless you do the research now in order to build these in the future.”

    It’s unclear what applications could come of humanity’s new knowledge of the existence of gravitational waves.

    It could be enough that we have learned something new about how our universe works. But if history gives us any indication, continued exploration will also provide additional benefits along the way.

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 2:25 pm on April 24, 2017 Permalink | Reply
    Tags: , , , Proton-proton collisions, , Symmetry Magazine   

    From Symmetry: “A tiny droplet of the early universe?” 

    Symmetry Mag


    Sarah Charley

    Particles seen by the ALICE experiment hint at the formation of quark-gluon plasma during proton-proton collisions. [ALREADY COVERED WITH AN ARTICLE FROM CERN HERE.]

    Mona Schweizer, CERN

    About 13.8 billion years ago, the universe was a hot, thick soup of quarks and gluons—the fundamental components that eventually combined into protons, neutrons and other hadrons.

    Scientists can produce this primitive particle soup, called the quark-gluon plasma, in collisions between heavy ions. But for the first time physicists on an experiment at the Large Hadron Collider have observed particle evidence of its creation in collisions between protons as well.

    The LHC collides protons during the majority of its run time. This new result, published in Nature Physics by the ALICE collaboration, challenges long-held notions about the nature of those proton-proton collisions and about possible phenomena that were previously missed.

    “Many people think that protons are too light to produce this extremely hot and dense plasma,” says Livio Bianchi, a postdoc at the University of Houston who worked on this analysis. “But these new results are making us question this assumption.”

    Scientists at the LHC and at the US Department of Energy’s Brookhaven National Laboratory’s Relativistic Heavy Ion Collider, or RHIC, have previously created quark-gluon plasma in gold-gold and lead-lead collisions.

    BNL RHIC Campus

    BNL/RHIC Star


    CERN/LHC Map

    CERN LHC Tunnel


    In the quark gluon plasma, mid-sized quarks—such as strange quarks—freely roam and eventually bond into bigger, composite particles (similar to the way quartz crystals grow within molten granite rocks as they slowly cool). These hadrons are ejected as the plasma fizzles out and serve as a telltale signature of their soupy origin. ALICE researchers noticed numerous proton-proton collisions emitting strange hadrons at an elevated rate.

    “In proton collisions that produced many particles, we saw more hadrons containing strange quarks than predicted,” says Rene Bellwied, a professor at the University of Houston. “And interestingly, we saw an even bigger gap between the predicted number and our experimental results when we examined particles containing two or three strange quarks.”

    From a theoretical perspective, a proliferation of strange hadrons is not enough to definitively confirm the existence of quark-gluon plasma. Rather, it could be the result of some other unknown processes occurring at the subatomic scale.

    “This measurement is of great interest to quark-gluon-plasma researchers who wonder how a possible QGP signature can arise in proton-proton collisions,” says Urs Wiedemann, a theorist at CERN. “But it is also of great interest for high energy physicists who have never encountered such a phenomenon in proton-proton collisions.”

    Earlier research at the LHC found that the spatial orientation of particles produced during some proton-proton collisions mirrored the patterns created during heavy-ion collisions, suggesting that maybe these two types of collisions have more in common than originally predicted. Scientists working on the ALICE experiment will need to explore multiple characteristics of these strange proton-proton collisions before they can confirm if they are really seeing a miniscule droplet of the early universe.

    “Quark-gluon plasma is a liquid, so we also need to look at the hydrodynamic features,” Bianchi says. “The composition of the escaping particles is not enough on its own.”

    This finding comes from data collected the first run of the LHC between 2009 and 2013. More research over the next few years will help scientists determine whether the LHC can really make quark-gluon plasma in proton-proton collisions.

    “We are very excited about this discovery,” says Federico Antinori, spokesperson of the ALICE collaboration. “We are again learning a lot about this extreme state of matter. Being able to isolate the quark-gluon-plasma-like phenomena in a smaller and simpler system, such as the collision between two protons, opens up an entirely new dimension for the study of the properties of the primordial state that our universe emerged from.”

    Other experiments, such as those using RHIC, will provide more information about the observable traits and experimental characteristics of quark-gluon plasmas at lower energies, enabling researchers to gain a more complete picture of the characteristics of this primordial particle soup.

    “The field makes far more progress by sharing techniques and comparing results than we would be able to with one facility alone,” says James Dunlop, a researcher at RHIC. “We look forward to seeing further discoveries from our colleagues in ALICE.”

    See the full article here .

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  • richardmitnick 12:29 pm on April 19, 2017 Permalink | Reply
    Tags: A new search to watch from LHCb, , , Symmetry Magazine   

    From Symmetry: “A new search to watch from LHCb” 

    Symmetry Mag


    Sarah Charley

    A new result from the LHCb experiment could be an early indicator of an inconsistency in the Standard Model.


    The subatomic universe is an intricate mosaic of particles and forces. The Standard Model of particle physics is a time-tested instruction manual that precisely predicts how particles and forces behave.

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

    But it’s incomplete, ignoring phenomena such as gravity and dark matter.

    Today the LHCb experiment at CERN European research center released a result that could be an early indication of new, undiscovered physics beyond the Standard Model.

    However, more data is needed before LHCb scientists can definitively claim they’ve found a crack in the world’s most robust roadmap to the subatomic universe.

    “In particle physics, you can’t just snap your fingers and claim a discovery,” says Marie-Hélène Schune, a researcher on the LHCb experiment from Le Centre National de la Recherche Scientifique in Orsay, France. “It’s not magic. It’s long, hard work and you must be obstinate when facing problems. We always question everything and never take anything for granted.”

    The LHCb experiment records and analyzes the decay patterns of rare hadrons—particles made of quarks—that are produced in the Large Hadron Collider’s energetic proton-proton collisions.

    CERN/LHC Map

    CERN LHC Tube


    By comparing the experimental results to the Standard Model’s predictions, scientists can search for discrepancies. Significant deviations between the theory and experimental results could be an early indication of an undiscovered particle or force at play.

    This new result looks at hadrons containing a bottom quark as they transform into hadrons containing a strange quark. This rare decay pattern can generate either two electrons or two muons as byproducts. Electrons and muons are different types or “flavors” of particles called leptons. The Standard Model predicts that the production of electrons and muons should be equally favorable—essentially a subatomic coin toss every time this transformation occurs.

    “As far as the Standard Model is concerned, electrons, muons and tau leptons are completely interchangeable,” Schune says. “It’s completely blind to lepton flavors; only the large mass difference of the tau lepton plays a role in certain processes. This 50-50 prediction for muons and electrons is very precise.”

    But instead of finding a 50-50 ratio between muons and electrons, the latest results from the LHCb experiment show that it’s more like 40 muons generated for every 60 electrons.

    “If this initial result becomes stronger with more data, it could mean that there are other, invisible particles involved in this process that see flavor,” Schune says. “We’ll leave it up to the theorists’ imaginations to figure out what’s going on.”

    However, just like any coin-toss, it’s difficult to know if this discrepancy is the result of an unknown favoritism or the consequence of chance. To delineate between these two possibilities, scientists wait until they hit a certain statistical threshold before claiming a discovery, often 5 sigma.

    “Five sigma is a measurement of statistical deviation and means there is only a 1-in-3.5-million chance that the Standard Model is correct and our result is just an unlucky statistical fluke,” Schune says. “That’s a pretty good indication that it’s not chance, but rather the first sightings of a new subatomic process.”

    Currently, this new result is at approximately 2.5 standard deviations, which means there is about a 1-in-125 possibility that there’s no new physics at play and the experimenters are just the unfortunate victims of statistical fluctuation.

    This isn’t the first time that the LHCb experiment has seen unexpected behavior in related processes. Hassan Jawahery from the University of Maryland also works on the LHCb experiment and is studying another particle decay involving bottom quarks transforming into charm quarks. He and his colleagues are measuring the ratio of muons to tau leptons generated during this decay.

    “Correcting for the large mass differences between muons and tau leptons, we’d expect to see about 25 taus produced for every 100 muons,” Jawahery says. “We measured a ratio of 34 taus for every 100 muons.”

    On its own, this measurement is below the line of statistical significance needed to raise an eyebrow. However, two other experiments—the BaBar experiment at SLAC and the Belle experiment in Japan—also measured this process and saw something similar.

    “We might be seeing the first hints of a new particle or force throwing its weight around during two independent subatomic processes,” Jawahery says. “It’s tantalizing, but as experimentalists we are still waiting for all these individual results to grow in significance before we get too excited.”

    More data and improved experimental techniques will help the LHCb experiment and its counterparts narrow in on these processes and confirm if there really is something funny happening behind the scenes in the subatomic universe.

    “Conceptually, these measurements are very simple,” Schune says. “But practically, they are very challenging to perform. These first results are all from data collected between 2011 and 2012 during Run 1 of the LHC. It will be intriguing to see if data from Run 2 shows the same thing.”

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.

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