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  • richardmitnick 2:27 pm on August 25, 2016 Permalink | Reply
    Tags: , Don Lincoln, , , ,   

    From Don Lincoln via CNN: “A new planet in our neighborhood — how likely is life?” 

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    CNN

    August 24, 2016

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    Dr. Don Lincoln is a senior physicist at Fermilab and does research using the Large Hadron Collider. He has written numerous books and produces a series of science education videos. He is the author of Alien Universe: Extraterrestrial Life in Our Minds and in the Cosmos. Follow him on Facebook. The opinions expressed in this commentary are solely those of the author.

    Space. The final frontier.

    These words inspired many young people to enter science (including me), but I’ll bet that’s especially true for the team who announced Wednesday that they had found evidence of an Earth-like planet orbiting Proxima Centauri, our closest star. This planet is tentatively called Proxima b.

    Pale Red Dot
    Pale Red Dot project at ESO

    Scientists working at the European Southern Observatory (ESO), using the La Silla telescope, claim to have discovered the closest exoplanet to Earth.

    ESO 3.6m telescope & HARPS at LaSilla
    ESO 3.6m telescope & HARPS at LaSilla, Chile

    Exoplanet, of course, means planets orbiting stars other than the Sun. Over 3,000 exoplanets have been discovered by facilities like the ESO and the Kepler orbiting observatory. Most of them are huge planets orbiting very near their star — Jupiter-like planets heated to temperatures guaranteed to sterilize them of life as we know it.

    In recent years, instrumentation has improved to the point that not only can individual planets be found, but even complete solar systems, consisting of many planets. This has been a heady time for planet hunters.

    The goal of those inspired by Star Trek’s opening words has not been to find planets, but to find planets that are like Earth — meaning at a temperature on which liquid water could be present and which could theoretically support some form of life. This is what astronomers call “the habitable zone.” In addition, we’d like to find a planet that is nearby.

    After all, space is huge and human spacecraft using current technology would take tens of thousands of years to get to even this, our closest celestial neighbor. To give a sense of scale, that’s longer than human civilization has existed. There are plans under discussion that might reduce travel time to a more manageable duration, even less than a single human lifespan.

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    Related article: Proxima b: Closest rocky planet to our solar system found

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker
    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    So what might this newly discovered planet look like? Well, even though its temperature is thought to be such that liquid water could exist, you shouldn’t imagine a lush and verdant world, with lovely blue waters, sandy beaches, lush and green plants, with an excited alien fish occasionally breaching the waters. There are lots of reasons why these are unreasonable expectations.

    Setting aside the possibility of life for a moment, Proxima Centauri is a red dwarf, which is the most common type of star in the galaxy. Red dwarfs are much smaller than our Sun. For instance, Proxima Centauri is only about 1.5 times larger than Jupiter. Red dwarfs are very dim. For instance, in the visible spectrum that we use to see, Proxima Centauri gives off 0.0056% as much as light as the Sun.

    Most of the light given off by Proxima Centauri is in the infrared region, but even if you compare all of the light emitted by Proxima Centauri in all wavelengths to the amount emitted by the Sun, Proxima Centauri still emits only 0.17% as much light as our own life-giving stellar companion. The star also emits as much x-rays as our own Sun, but Proxima b is much closer to its stellar parent, so the surface receives far more x-rays than Earth.

    In addition to being a very dim star, Proxima Centauri is known to be a “flare star,” which means the star periodically gives off far more light than usual. During these flares, the x-ray emission can go up tenfold.

    Because of the star’s small size, a planet in the habitable zone will have to be in a very small orbit, taking under two weeks to complete a single orbit. Any planet that close to a star will be “tidally locked,” which means that one face of the planet will constantly face the star. This is just like the Earth and Moon, where we see only one side of the Moon throughout the course of the Month. Proxima Centauri’s planetary companion will likely have one side in perpetual daylight, while the other is in perpetual night.

    So what about life? Are there any chances that an alien lizard might bask in Proxima Centauri’s light or try to find shade under an alien tree? Well, given the instability of the light emitted by the parent star, the answer is likely no, although the real answer to that question is obviously something for observations to answer.

    Given the very dim light output of the star, it is likely that any hypothetical plants would have to be black, as black is the most light-absorbent color. “Sunlight” would be precious and evolution would drive alien plants to find ways to collect every bit of energy that falls on them.

    Realistically, the prospect of life is improbable. This planet is unlikely to be a haven for people trying to escape the ecological issues of Earth, so we should not view this discovery as a way to ignore our own ecosystem.

    Still, the question of extraterrestrial life is a fascinating one, so astronomers are devising techniques to look at the planet’s atmosphere. Certain chemicals, like oxygen or methane, cannot exist long in a planet’s atmosphere without being constantly replenished by living organisms. Observing them would be strong evidence for life.

    So, what’s the bottom line? First, the discovery, if confirmed is extremely exciting. The existence of a nearby planet in the habitable zone will perhaps increase the interest in efforts like Project Starshot, which aims to send microprobes to Proxima Centauri with a transit time of about twenty years. It may well be that this discovery will excite an entirely new generation of the prospect “to boldly go where no one has gone before.”

    See the full article here .

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  • richardmitnick 10:32 am on July 25, 2016 Permalink | Reply
    Tags: , Don Lincoln, , , Possible fifth force?,   

    From Don Lincoln of FNAL on livescience: “A Fifth Force: Fact or Fiction” 

    Livescience

    FNAL Icon
    FNAL

    FNAL Don Lincoln
    Don lincoln

    July 5, 2016

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    Has a Hungarian lab really found evidence of a fifth force of nature? Credit: Jurik Peter / Shutterstock.com

    Science and the internet have an uneasy relationship: Science tends to move forward through a careful and tedious evaluation of data and theory, and the process can take years to complete. In contrast, the internet community generally has the attention span of Dory, the absent-minded fish of Finding Nemo(and now Finding Dory) — a meme here, a celebrity picture there — oh, look … a funny cat video.

    Thus people who are interested in serious science should be extremely cautious when they read an online story that purports to be a paradigm-shifting scientific discovery. A recent example is one suggesting that a new force of nature might have been discovered. If true, that would mean that we have to rewrite the textbooks.

    A fifth force

    So what has been claimed?

    In an article submitted on April 7, 2015, to the arXiv repository of physics papers, a group of Hungarian researchers reported on a study in which they focused an intense beam of protons (particles found in the center of atoms) on thin lithium targets. The collisions created excited nuclei of beryllium-8, which decayed into ordinary beryllium-8 and pairs of electron-positron particles. (The positron is the antimatter equivalent of the electron.)

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    The Standard Model is the collection of theories that describe the smallest experimentally observed particles of matter and the interactions between energy and matter. Credit: Karl Tate, LiveScience Infographic Artist

    They claimed that their data could not be explained by known physical phenomena in the Standard Model, the reigning model governing particle physics. But, they purported, they could explain the data if a new particle existed with a mass of approximately 17 million electron volts, which is 32.7 times heavier than an electron and just shy of 2 percent the mass of a proton. The particles that emerge at this energy range, which is relatively low by modern standards, have been well studied. And so it would be very surprising if a new particle were discovered in this energy regime.

    However, the measurement survived peer review and was published on Jan. 26, 2016, in the journal Physical Review Letters, which is one of the most prestigious physics journals in the world. In this publication, the researchers, and this research, cleared an impressive hurdle.

    Their measurement received little attention until a group of theoretical physicists from the University of California, Irvine (UCI), turned their attention to it. As theorists commonly do with a controversial physics measurement, the team compared it with the body of work that has been assembled over the last century or so, to see if the new data are consistent or inconsistent with the existing body of knowledge. In this case, they looked at about a dozen published studies.

    What they found is that though the measurement didn’t conflict with any past studies, it seemed to be something never before observed — and something that couldn’t be explained by the Standard Model.

    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.
    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

    New theoretical framework

    To make sense of the Hungarian measurement, then, this group of UCI theorists invented a new theory.

    The theory invented by the Irvine group is really quite exotic. They start with the very reasonable premise that the possible new particle is something that is not described by existing theory. This makes sense because the possible new particle is very low mass and would have been discovered before if it were governed by known physics. If this were a new particle governed by new physics, perhaps a new force is involved. Since traditionally physicists speak of four known fundamental forces (gravity, electromagnetism and the strong and weak nuclear forces), this hypothetical new force has been dubbed “the fifth force.”

    Theories and discoveries of a fifth force have a checkered history, going back decades, with measurements and ideas arising and disappearing with new data. On the other hand, there are mysteries not explained by ordinary physics like, for example, dark matter. While dark matter has historically been modeled as a single form of a stable and massive particle that experiences gravity and none of the other known forces, there is no reason that dark matter couldn’t experience forces that ordinary matter doesn’t experience. After all, ordinary matter experiences forces that dark matter doesn’t, so the hypothesis isn’t so silly.

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    There is no reason dark matter couldn’t experience forces that ordinary matter doesn’t experience. Here, in the galaxy cluster Abell 3827, dark matter was observed interacting with itself during a galaxy collision. Credit: ESO

    There are many ideas about forces that affect only dark matter and the term for this basic idea is called “complex dark matter.” One common idea is that there is a dark photon that interacts with a dark charge carried only by dark matter. This particle is a dark matter analog of the photon of ordinary matter that interacts with familiar electrical charge, with one exception: Some theories of complex dark matter imbue dark photons with mass, in stark contrast with ordinary photons.

    If dark photons exist, they can couple with ordinary matter (and ordinary photons) and decay into electron-positron pairs, which is what the Hungarian research group was investigating. Because dark photons don’t interact with ordinary electric charge, this coupling can only occur because of the vagaries of quantum mechanics. But if scientists started seeing an increase in electron-positron pairs, that might mean they were observing a dark photon.

    The Irvine group found a model that included a “protophobic” particle that was not ruled out by earlier measurements and would explain the Hungarian result. Particles that are “protophobic,” which literally means “fear of protons,” rarely or never interact with protons but can interact with neutrons (neutrophilic).

    The particle proposed by the Irvine group experiences a fifth and unknown force, which is in the range of 12 femtometers, or about 12 times bigger than a proton. The particle is protophobic and neutrophilic. The proposed particle has a mass of 17 million electron volts and can decay into electron-positron pairs. In addition to explaining the Hungarian measurement, such a particle would help explain some discrepancies seen by other experiments. This last consequence adds some weight to the idea.

    Paradigm-shifting force?

    So this is the status.

    What is likely to be true? Obviously, data is king. Other experiments will need to confirm or refute the measurement. Nothing else really matters. But that will take a year or so and having some idea before then might be nice. The best way to estimate the likelihood the finding is real is to look at the reputations of the various researchers involved. This is clearly a shoddy way to do science, but it will help shade your expectations.

    So let’s start with the Irvine group. Many of them (the senior ones, typically) are well- regarded and established members of the field, with substantive and solid papers in their past. The group includes a spectrum of ages, with both senior and junior members. In the interest of full disclosure, I know some of them personally and, indeed, two of them have read the theoretical portions of chapters of books I have written for the public to ensure that I didn’t say anything stupid. (By the way, they didn’t find any gaffes, but they certainly helped clarify certain points.) That certainly demonstrates my high regard for members of the Irvine group, but possibly taints my opinion. In my judgment, they almost certainly did a thorough and professional job of comparing their new model to existing data. They have found a small and unexplored region of possible theories that could exist.

    On the other hand, the theory is pretty speculative and highly improbable. This isn’t an indictment … all proposed theories could be labeled in this way. After all, the Standard Model, which governs particle physics, is nearly a half century old and has been thoroughly explored. In addition, ALL new theoretical ideas are speculative and improbable and almost all of them are wrong. This also isn’t an indictment. There are many ways to add possible modifications to existing theories to account for new phenomena. They can’t all be right. Sometimes none of the proposed ideas are right.

    However, we can conclude from the reputation of the group’s members that they have generated a new idea and have compared it to all relevant existing data. The fact that they released their model means that it survived their tests and thus it remains a credible, if improbable, possibility.

    What about the Hungarian group? I know none of them personally, but the article was published in Physical Review Letters — a chalk mark in the win column. However, the group has also published two previous papers in which comparable anomalies were observed, including a possible particle with a mass of 12 million electron volts and a second publication claiming the discovery of a particle with a mass of about 14 million electron volts. Both of these claims were subsequently falsified by other experiments.

    Further, the Hungarian group has never satisfactorily disclosed what error was made that resulted in these erroneous claims. Another possible red flag is that the group rarely publishes data that doesn’t claim anomalies. That is improbable. In my own research career, most publications were confirmation of existing theories. Anomalies that persist are very, very, rare.

    So what’s the bottom line? Should you be excited about this new possible discovery? Well…sure…possible discoveries are always exciting. The Standard Model has stood the test of time for half a century, but there are unexplained mysteries and the scientific community is always looking for the discovery that points us in the direction of a new and improved theory. But what are the odds that this measurement and theory will lead to the scientific world accepting a new force with a range of 12 fm and with a particle that shuns protons? My sense is that this a long shot. I am not so sanguine as to the chances of this outcome.

    Of course, this opinion is only that…an opinion, albeit an informed one. Other experiments will also be looking for dark photons because, even if the Hungarian measurement doesn’t stand up to scrutiny, there is still a real problem with dark matter. Many experiments looking for dark photons will explore the same parameter space (e.g. energy, mass and decay modes) in which the Hungarian researchers claim to have found an anomaly. We will soon (within a year) know if this anomaly is a discovery or just another bump in the data that temporarily excited the community, only to be discarded as better data is recorded. And, no matter the outcome, good and better science will be the eventual result.

    See the full article here .

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  • richardmitnick 3:40 pm on July 6, 2016 Permalink | Reply
    Tags: , Don Lincoln, , , Quantum Color   

    From Don Lincoln at FNAL: “Quantum Color” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

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

    From Don Lincoln, Fermilab

    FNAL Don Lincoln
    Don Loncoln

    Published on Jun 17, 2016 [Just made it to social media]

    The strongest force in the universe is the strong nuclear force and it governs the behavior of quarks and gluons inside protons and neutrons. The name of the theory that governs this force is quantum chromodynamics, or QCD. In this video, Fermilab’s Dr. Don Lincoln explains the intricacies of this dominant component of the Standard Model.

    Watch, enjoy learn.

    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 5:57 pm on June 20, 2016 Permalink | Reply
    Tags: , Don Lincoln, , , QCD: Quantum Chromodynamics   

    From Don Lincoln at FNAL: “QCD: Quantum Chromodynamics” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    FNAL Don Lincoln
    Don Lincoln

    The strongest force in the universe is the strong nuclear force and it governs the behavior of quarks and gluons inside protons and neutrons. The name of the theory that governs this force is quantum chromodynamics, or QCD. In this video, Fermilab’s Dr. Don Lincoln explains the intricacies of this dominant component of the Standard Model.

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

    Watch, enjoy, learn.

    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 5:11 pm on June 17, 2016 Permalink | Reply
    Tags: , , Don Lincoln, , ,   

    From Don Lincoln at FNAL: “The triumphant Standard Model” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

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

    June 17, 2016

    FNAL Don Lincoln
    Don Lincoln

    In high-end research, there are a couple of deeply compelling types of data analyses that scientists do. There are those that break the existing scientific understanding and rewrite the textbooks. Those are exciting. But there are also those in which a highly successful theory is tested in a regime never before explored. There can also be two types of outcome. If the theory fails to explain the data, we have a discovery of the type I mentioned first. But it is also possible that the theory explains the data perfectly well. If so, that means that you’ve proven that the existing theory is even more successful than was originally known. That’s a different kind of success. It means that predictions made in one realm taught scientists enough to understand far more.

    In the LHC, pairs of protons are collided together with the unprecedented energy of 13 trillion electronvolts of energy.

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

    Before 2015, when the data in this analysis was recorded, the highest energy ever studied by humanity was only 8 trillion electronvolts. So, already we know that the new data is 63 percent higher in terms of energy reach as compared to the old data. To get a visceral sense of what that means, imagine that your bank told you that they made a mistake and that for every dollar you thought you had in your account, you actually had $1.63. I’m guessing you’d start planning for an awesome vacation or perhaps an earlier retirement.

    When the protons collide, most commonly, a quark or gluon from each proton hits a quark or gluon from the other proton and knocks them out of the collision area into the detector. As the quarks and gluons leave the collision area, they convert into sprays of particles that travel in roughly the same direction. These are called jets. Physicists study the location and energy of the jets in the detector and compare them to the predicted distribution.

    CMS scientists studied the production patterns of jets at a collision energy of 13 trillion electronvolts and found that they agreed with the predictions of the Standard Model with the same level of precision seen at lower energy measurements.

    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.
    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

    This result comes with a small sadness because this means that new physics hasn’t been discovered. On the other hand, it is a resounding endorsement of the theory of quantum chromodynamics, or QCD, which is the portion of the Standard Model that deals explicitly with quark and gluon scattering. QCD, first worked out nearly half a century ago, continues its decades-long track record of success.

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    Scientists are constantly exploring the universe, seeing what happens when existing theories are tested in new realms. In today’s analysis, scientists put the leading theory of quark scattering to the test, studying what happens when it is compared to data taken at energies over 60 percent higher than ever before achieved.

    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 10:48 am on May 25, 2016 Permalink | Reply
    Tags: , Don Lincoln, , The Strong Nuclear Force   

    From Don Lincoln at FNAL: “The Strong Nuclear Force “ 

    FNAL II photo

    FNAL Art Image

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

    FNAL Don Lincoln
    FNAL Don Lincoln

    Scientists are aware of four fundamental forces- gravity, electromagnetism, and the strong and weak nuclear forces. Most people have at least some familiarity with gravity and electromagnetism, but not the other two. How is it that scientists are so certain that two additional forces exist? In this video, Fermilab’s Dr. Don Lincoln explains why scientists are so certain that the strong force exists.

    Watch, enjoy, learn.

    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 8:53 am on May 5, 2016 Permalink | Reply
    Tags: , Don Lincoln, , FNAL G-2,   

    From Don Lincoln at FNAL: “The physics of g-2” 

    FNAL II photo

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

    FNAL Don Lincoln
    Don Lincoln

    At any time in history, a few scientific measurements disagreed with the best theoretical predictions of the time. Currently, one such discrepancy involves the measurement of the strength of the magnetic field of a subatomic particle called a muon. In this video, Fermilab’s Dr. Don Lincoln explains this mystery and sketches ongoing efforts to determine if this disagreement signifies a discovery. If it does, this measurement will mean that we will have to rewrite the textbooks.


    Access the mp4 video here .

    Watch, enjoy, learn.

    FNAL G-2
    FNAL G-2

    FNAL Muon g-2 studio
    FNAL Muon g-2 studio

    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 7:57 am on April 14, 2016 Permalink | Reply
    Tags: , , , Don Lincoln,   

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

    Livescience

    April 12, 2016

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

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

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

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

    A particle smasher reborn

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

    CERN ATLAS Higgs Event
    CERN ATLAS Higgs Event

    CERN CMS Higgs Event
    CERN CMS Higgs Event

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

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

    FNAL/Tevatron map
    FNAL/Tevatron map

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

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

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

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

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

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

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

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

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

    So what’s expected in 2016?

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

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

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

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

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

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

    Luminous beams

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

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

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

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

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

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

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

    Illuminating new science

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

    Higgs Boson Event
    Higgs Boson Event

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

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

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

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

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

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

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

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

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

     
  • richardmitnick 7:14 pm on March 30, 2016 Permalink | Reply
    Tags: , Don Lincoln, , , Quantum electrodynamics   

    From Don Lincoln at FNAL: “Quantum electrodynamics: theory” video 

    FNAL II photo

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

    FNAL Don Lincoln
    Don Lincoln

    The Standard Model of particle physics is composed of several theories that are added together.

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

    The most precise component theory is the theory of quantum electrodynamics or QED. In this video, Fermilab’s Dr. Don Lincoln explains how theoretical QED calculations can be done. This video links to other videos, giving the viewer a deep understanding of the process.


    Access mp4 video here .

    Watch, enjoy, learn.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 10:32 am on March 25, 2016 Permalink | Reply
    Tags: , Don Lincoln, ,   

    From Don Lincoln of FNAL: “Theoretical physics: insider’s tricks “ 

    FNAL II photo

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

    Mar 24, 2016

    FNAL Don Lincoln
    Don Lincoln

    Theoretical particle physics employs very difficult mathematics, so difficult in fact that it is impossible to solve the equations. In order to make progress, scientists employ a mathematical technique called perturbation theory. This method makes it possible to solve very difficult problems with very good precision. In this video, Fermilab’s Dr. Don Lincoln shows just how easy it is to understand this powerful technique.


    Access mp4 video here.

    Watch, enjoy, learn.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.

     
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