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  • richardmitnick 3:16 pm on July 18, 2018 Permalink | Reply
    Tags: , , , CERN CMS, , Meenakshi Narain, , , ,   

    From Brown University: Women in STEM- “Brown physicist elected to represent U.S. in Large Hadron Collider experiment” Meenakshi Narain 

    Brown University
    From Brown University

    July 18, 2018
    Kevin Stacey
    kevin_stacey@brown.edu
    401-863-3766

    1
    Meenakshi Narain

    Meenakshi Narain will lead the collaboration board for U.S. institutions participating the CMS experiment at the Large Hadron Collider, an experiment pushing the frontiers of modern particle physics.

    Brown University physics professor Meenakshi Narain has been tapped to chair the collaboration board of U.S. institutions in the Compact Muon Solenoid (CMS) experiment, one of two large-scale experiments happening at the Large Hadron Collider particle accelerator headquartered in Geneva.

    CERN CMS Higgs Event


    CERN/CMS Detector

    The CMS experiment is an international collaboration of 4,000 particle physicists, engineers, computer scientists, technicians and students from approximately 200 institutes and universities around the world. With more than 1,200 participants, the U.S. CMS collaboration is the largest national group in the global experiment. As collaboration board chair, Narain will represent U.S. institutions within the broader collaboration, as well as with U.S. funding agencies. The board also plays a key role in shaping the vision and direction of the U.S. collaboration.

    “I’m honored that my colleagues from the 50 U.S. institutions that collaborate with the CMS Experiment have chosen me to represent them,” Narain said. “I see this position as an opportunity to help U.S. CMS to become a more inclusive community and to enable all young scientists to contribute to their full potential to CMS and find rewarding career opportunities in academia and industry.”

    Narain and other Brown physicists working with the CMS experiment played key roles in the discovery in 2012 of the Higgs Boson, which at the time was the final missing piece in the Standard Model of particle physics. After the Higgs, the CMS experiment has been searching for particles beyond the Standard Model, including a potential candidate particle for dark matter, the mysterious stuff thought to account for a majority of matter in the universe.

    Narain says part of her job is to maintain the research synergy created by the numerous U.S. scientists and institutions involved in the collaboration as they analyze data from the collider’s latest run. At the same time, the experiment must also prepare for the next stage of the Large Hadron Collider program slated to start around 2026. The next stage involves beam intensities five times higher the current level and 10 times more data than has been acquired to date. That will require parts of the CMS detector to be rebuilt.

    “We need the resources to maintain the detector during the current run as well as to start building the upgrades,” Narain said. “I will work with funding agencies to communicate what we’ll need to both maintain our involvement in the data analysis and play a leading role in the upgrade of the detector.”

    Narain says that as the first woman to chair the collaboration board, she plans to work toward cultivating more diversity in what is currently the largest physics collaboration in the U.S.

    “With this comes the opportunity to promote women and other underrepresented minorities to have the opportunity to develop their careers to their fullest potential,” she said. “I hope that I will be able to improve our community in the U.S. and in CMS in general to be more inclusive during my two-year term.”

    Narain joined the Brown faculty in 2007 and has worked at the Large Hadron Collider together with the Brown team that includes professors David Cutts, Ulrich Heintz and Greg Landsberg. She was also a member of the DZero experiment at the Fermi National Accelerator Laboratory, where she played a prominent role in the discoveries of the top quark and the anti-top quark, two fundamental constituents of matter. She is a fellow of the American Physical Society and the author of more than 500 journal articles.

    See the full article here .

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    Welcome to Brown

    Brown U Robinson Hall
    Located in historic Providence, Rhode Island and founded in 1764, Brown University is the seventh-oldest college in the United States. Brown is an independent, coeducational Ivy League institution comprising undergraduate and graduate programs, plus the Alpert Medical School, School of Public Health, School of Engineering, and the School of Professional Studies.

    With its talented and motivated student body and accomplished faculty, Brown is a leading research university that maintains a particular commitment to exceptional undergraduate instruction.

    Brown’s vibrant, diverse community consists of 6,000 undergraduates, 2,000 graduate students, 400 medical school students, more than 5,000 summer, visiting and online students, and nearly 700 faculty members. Brown students come from all 50 states and more than 100 countries.

    Undergraduates pursue bachelor’s degrees in more than 70 concentrations, ranging from Egyptology to cognitive neuroscience. Anything’s possible at Brown—the university’s commitment to undergraduate freedom means students must take responsibility as architects of their courses of study.

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  • richardmitnick 9:23 am on June 4, 2018 Permalink | Reply
    Tags: , , , CERN CMS, , , , ,   

    From CERN Courier: “Higgs boson reaches the top” 


    From CERN Courier

    Jun 1, 2018
    No writer credit

    The CMS collaboration has published the first direct observation of the coupling between the Higgs boson and the top quark, offering an important probe of the consistency of the Standard Model (SM). In the SM, the Higgs boson interacts with fermions via a Yukawa coupling, the strength of which is proportional to the fermion mass. Since the top quark is the heaviest particle in the SM, its coupling to the Higgs boson is expected to be the largest and thus the dominant contribution to many loop processes, making it a sensitive probe of hypothetical new physics.

    1
    Combined likelihood analysis

    The associated production of a Higgs boson with a top quark–antiquark pair (ttH) is the best direct probe of the top-Higgs Yukawa coupling with minimal model dependence, and thus a crucial element to verify the SM nature of the Higgs boson. However, its small production rate – constituting only about 1% of the total Higgs production cross-section – makes the ttH measurement a considerable challenge.

    The CMS and ATLAS collaborations reported first evidence for the process last year, based on LHC data collected at a centre-of-mass energy of 13 TeV (CERN Courier May 2017 p49 and December 2017 p12). The first observation, constituting statistical significance above five standard deviations, is based on an analysis of the full 2016 CMS dataset recorded at an energy of 13 TeV and by combining these results with those collected at lower energies.

    The ttH process gives rise to a wide variety of final states, and the new CMS analysis combines results from a number of them. Top quarks decay almost exclusively to a bottom quark (b) and a W boson, the latter subsequently decaying either to a quark and an antiquark or to a charged lepton and its associated neutrino. The Higgs-boson decay channels include the decay to a bb quark pair, a τ+τ– lepton pair, a photon pair, and combinations of quarks and leptons from the decay of intermediate on- or off-shell W and Z bosons. These five Higgs-boson decay channels were analysed by CMS using sophisticated methods, such as multivariate techniques, to separate signal from background events. Each channel poses different experimental challenges: the bb channel has the largest rate but suffers from a large background of events containing a top-quark pair and jets, while the photon and Z-boson pair channels offer the highest signal-to-background ratio at a very small rate.

    CMS observed an excess of events with respect to the background-only hypothesis at a significance of 5.2 standard deviations. The measured values of the signal strength in the considered channels are consistent with each other, and a combined value of 1.26 +0.31/–0.26 times the SM expectation is obtained (see figure). The measured production rate is thus consistent with the SM prediction within one standard deviation. The result establishes the direct Yukawa coupling of the Higgs boson to the top quark, marking an important milestone in our understanding of the properties of the Higgs boson.

    Further reading

    https://arxiv.org/abs/1804.02610
    https://arxiv.org/abs/1803.05485
    https://journals.aps.org/prd/abstract/10.1103/PhysRevD.97.072003

    See the full article here .


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    Please help promote STEM in your local schools.


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    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

     
  • richardmitnick 8:58 am on June 4, 2018 Permalink | Reply
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    From CERN CMS and ATLAS: “The Higgs boson reveals its affinity for the top quark” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    New results from the ATLAS and CMS experiments at the LHC reveal how strongly the Higgs boson interacts with the heaviest known elementary particle, the top quark, corroborating our understanding of the Higgs and setting constraints on new physics.

    CERN CMS Event NOV 2010

    From CERN CMS

    By CMS

    The first observation of the simultaneous production of a Higgs boson with a top quark-antiquark pair is being published today in the journal Physical Review Letters. This major milestone, first reported by the CMS Collaboration in early April 2018, unambiguously demonstrates the interaction of the Higgs boson and top quarks, which are the heaviest known subatomic particles. It is an important step forward in our understanding of the origin of mass. The paper features as a PRL Editors’ Suggestion and also has a Physics Viewpoint article published about it.

    ________________________________________________________
    From CMS – first reported by the CMS Collaboration in early April 2018

    The observation of a Higgs boson in 2012 at the Large Hadron Collider marked the starting point of a broad experimental program to determine the properties of the newly discovered particle. In the standard model, the Higgs boson couples to fermions in a Yukawa-type interaction, with a coupling strength proportional to the fermion mass. While decays into γγ, ZZ, WW, and ττ final states have been observed and there is evidence for the direct decay of the particle to the bb (down-type quarks) final state, the decay to the tt (up-type quarks) final state is not kinematically possible. Therefore, it is of paramount importance to probe the coupling of the Higgs boson to the top quark, the heaviest known fermion, by producing the Higgs in the fusion of a top quark-antiquark pair (left diagram) or through radiation from a top quark (right diagram).

    1

    The associated production of a Higgs boson and a top quark-antiquark pair (ttH production) is a direct probe of the top–Higgs coupling. Hence the observation of this production mechanism is one of the primary objectives of the the Higgs physics program at the LHC.

    The CMS experiment has searched for ttH production in the data collected at the center-of-mass energies of 7, 8, and 13 TeV with the Higgs boson decaying to pairs of W bosons, Z bosons, photons, τ leptons, or bottom quark jets. The results have been combined to maximize the sensitivity to this challenging and yet fundamental process.

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    An excess of events is observed, with a significance of 5.2 standard deviations, over the expectation from the background-only hypothesis. The corresponding expected significance for the standard model Higgs boson with a mass of 125.09 GeV is 4.2 standard deviations. The measured production rate is consistent with the standard model prediction within one standard deviation.

    In addition to comprising the first observation of a new Higgs boson production mechanism, this measurement establishes the tree-level coupling of the Higgs boson to the top quark, and hence to an up-type quark, and is another milestone towards the measurement of the Higgs boson coupling to fermions.
    ________________________________________________________

    4

    An event candidate for the production of a top quark and top anti-quark pair in conjunction with a Higgs Boson in the CMS detector. The Higgs decays into a tau+ lepton and a tau- lepton; the tau+ in turn decays into hadrons and the tau- decays into an electron. The decay product symbols are in blue. The top quark decays into three jets (sprays of lighter particles) whose names are given in purple. One of these is initiated by a b-quark. The top anti-quark decays into a muon and b-jet, whose names appear in red.

    Further reading:

    [1] CMS ttH observation journal article: Physical Review Letters, June 4, 2018

    See the full CMS article here.

    From CERN ATLAS

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    CERN ATLAS Event 2012

    New ATLAS result establishes production of Higgs boson in association with top quarks.

    This rare process is one of the most sensitive tests of the Higgs mechanism.

    By ATLAS Collaboration, 4th June 2018

    According to the Standard Model, quarks, charged leptons, and W and Z bosons obtain their mass through interactions with the Higgs field, a quantum fluctuation of which gives rise to the Higgs boson. To test this theory, ATLAS takes high-precision measurements of the interactions between the Higgs boson and these particles. While the ATLAS and CMS experiments at CERN’s Large Hadron Collider (LHC) had observed and measured the Higgs boson decaying to pairs of W or Z bosons, photons or tau leptons, the Higgs coupling to quarks had not – despite evidence – been observed.

    In results presented today at the LHCP2018 conference, the ATLAS Collaboration has observed the production of the Higgs boson together with a top-quark pair (known as “ttH” production). Only about 1% of all Higgs bosons are produced through this rare process. This result establishes a direct measurement of the interaction between the top quark and the Higgs boson (known as the “top quark Yukawa coupling”). As the top quark is the heaviest particle in the Standard Model, this measurement is one of the most sensitive tests of the Higgs mechanism.

    Previous ATLAS measurements using 2015 and 2016 data provided the first evidence for ttH production from a combination of channels where the Higgs boson decayed to two W or Z bosons (WW* or ZZ*), to a pair of tau leptons, to a pair of b-quarks, or to a pair of photons (“diphoton”). Those results have now been updated with the measurements of the diphoton and ZZ* decay modes that use the larger 2015-2017 dataset, and where improved reconstruction algorithms and new analysis techniques have increased the sensitivity of the measurements. The CMS Collaboration recently reported the observation of ttH production by combining 2015 and 2016 data with data taken at lower collision energies in earlier LHC runs.
    Evidence for ttH production in the diphoton channel in the 2015-2017 dataset

    The probability of a Higgs boson decaying to a diphoton pair is only about 0.2%, making the predicted rate for ttH production in this channel quite small. However, because the energy and direction of photons can be well measured with the ATLAS detector, the reconstructed mass peak obtained with this decay mode is narrow. It is therefore possible to observe a signal even when the number of events is low. Furthermore, regions with lower and higher reconstructed mass (called the “sidebands”) can be used to estimate the background under the signal peak using the data themselves, rendering this channel particularly robust.

    To optimize the measurement ATLAS employs machine learning techniques. Events consistent with the ttH kinematics are selected using “boosted decision tree” (BDT) algorithms that allow physicists to separate the events into multiple categories with different signal-to-background abundance ratios. Depending on the top-quark decay channel considered, the inputs given to the BDT are the momenta of the “jets” (collimated groups of particles that are produced by a quark or gluon), leptons and photons observed in each event. As the decay of a top quark always produces a b-quark, identifying jets that arise from b-quarks is essential for reducing backgrounds. To achieve this, ATLAS developed a b-identification algorithm (also based on machine learning); the b-identification decision for each jet is included in the BDT inputs.

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    Figure 1: Time-lapse animation showing the increasing ttH signal in the diphoton mass spectrum as more data are included in the measurement. (Image: ATLAS Collaboration/CERN)

    Each category is analysed separately by studying the distribution of the invariant mass of the diphoton candidates in selected events. This distribution is fit to a combination of signal (Higgs boson decay to diphoton in events containing a top-quark pair) and background (cases where the diphoton candidate does not arise from a Higgs boson or where the event does not contain a true top-quark pair). The numbers of fitted signal events in the different categories are then statistically combined, taking into account correlated experimental and theoretical systematic uncertainties.

    The result of the above procedure, using 80 fb-1 of data recorded in 2015, 2016 and the recent 2017 run of the LHC, is summarised in Figure 1, which shows the diphoton invariant mass distribution, summed over categories weighted by their signal purity. The significance of the observed signal is 4.1 standard deviations; the expected significance for Standard Model production is 3.7 standard deviations.

    Search continues for ttH production in the ZZ* channel in the 2015-2017 dataset.

    The decay of a Higgs boson to ZZ* with the subsequent decay of the ZZ* to four leptons is another channel where the Higgs mass peak is narrow. Due to the very clean detector signature of the four-lepton decay mode, this channel is essentially free of backgrounds apart from small contributions from Higgs bosons produced through other production modes than ttH. However, this decay mode is even rarer than that of diphotons, with less than one event expected from ttH production in the 80 fb-1 of the full 2015-2017 dataset. A dedicated search for this decay was performed, but no candidate events were found in the 2015-2017 ATLAS data.

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    Figure 2: Combined ttH production cross section, as well as cross sections measured in the individual analyses, divided by the SM cross section prediction. ML indicates the analysis of the two and three lepton final states (multilepton). The black lines show the total uncertainties, while the bands indicate the statistical and systematic uncertainties. The red line indicates the SM cross section prediction, and the grey band represents the theoretical uncertainties on the prediction. For the γγ and ZZ* channels to full dataset at 13 GeV (collected between 2015 and 2017) have been used, whereas the results of the other channels are based on the 2015 and 2016 data. (Image: ATLAS Collaboration/CERN)

    Combination with earlier ATLAS results

    The measurements described above have been combined with the previously reported searches for ttH that used 2015 and 2016 data. Decays of the Higgs boson to a b-quark pair and to a pair of W bosons or tau leptons had observed (expected) significances of 1.4 (1.6) and 4.2 (2.8) standard deviations, respectively.

    After the combination, the observed (expected) significance of the signal over the background is 5.8 (4.9) standard deviations. The ratio of the combined ttH cross section measurement and the cross section measurements separated by Higgs boson decay modes are presented in Figure 2. The measured ratio of 1.32 ± 0.27 is slightly larger than, but consistent with the Standard Model expectation.

    Further searches for the ttH process were performed using 7 and 8 TeV data collected during Run 1. When combined with the 2015-2017 results, the observed (expected) significance is 6.3 (5.1) standard deviations.

    Summary

    ATLAS has observed the production of the Higgs boson in association with a top-quark pair with a significance of 6.3 standard deviations over the background-only hypothesis. The measured ttH production cross section is consistent with the Standard Model prediction. This measurement provides direct evidence for the coupling of the Higgs boson to the top quark and supports the Standard Model mechanism whereby the top quark obtains its mass through interaction with the Higgs field.

    Evidence for the associated production of the Higgs boson and a top quark pair with the ATLAS detector Physical Review D

    See the full ATLAS article here .


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    Meet CERN in a variety of places:

    Quantum Diaries
    QuantumDiaries

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

    OTHER PROJECTS AT CERN

    CERN AEGIS

    CERN ALPHA

    CERN ALPHA

    CERN AMS

    CERN ACACUSA

    CERN ASACUSA

    CERN ATRAP

    CERN ATRAP

    CERN AWAKE

    CERN AWAKE

    CERN CAST

    CERN CAST Axion Solar Telescope

    CERN CLOUD

    CERN CLOUD

    CERN COMPASS

    CERN COMPASS

    CERN DIRAC

    CERN DIRAC

    CERN ISOLDE

    CERN ISOLDE

    CERN LHCf

    CERN LHCf

    CERN NA62

    CERN NA62

    CERN NTOF

    CERN TOTEM

    CERN UA9

     
  • richardmitnick 1:52 pm on April 20, 2018 Permalink | Reply
    Tags: , , CERN CMS, , , ,   

    From FNAL: “Turning up the luminosity: Fermilab contributes important CMS upgrades” 

    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.

    April 19, 2018
    Sarah Lawhun

    Fermilab is developing and testing a revolutionary particle detector concept, one that will enable the CMS detector at CERN’s Large Hadron Collider to handle 10 times the number of particle collisions currently being produced at the European machine — a virtual avalanche. This upgrade will make the LHC the world’s highest-energy proton smasher in the next decades.

    CERN CMS

    CERN CMS Higgs Event

    CERN CMS pre-Higgs Event

    At the LHC, two beams of protons are accelerated to nearly the speed of light around the collider’s 18-mile ring in opposite directions, colliding inside one of four detectors, including one called CMS. The protons smash together in the detector’s core, producing a plethora of subatomic particles that fly off in all directions.

    The detector — a gigantic, barrel-shaped device that could surround a whale if the instrument were hollow — is packed with layers of detectors that surround the collision site. Think of it as a superhigh-tech onion — a 14,000-ton onion equipped with billions of sensors in its core, buried 100 meters underground. These layers collect data from the particles emerging from the collisions, tracking their paths as they shoot away from the center.

    Higher luminosity for the Higgs

    In the late 2020s, CERN will turn up the LHC’s beam luminosity, or the number of protons packed into its beams, resulting in showers of even more particles.

    This increased abundance will give scientists more opportunities to reveal new particles and processes, helping us refine our understanding of how the universe works.

    The CMS and ATLAS co-discovered the Higgs boson in 2012, a discovery that led to a Nobel Prize. Now, both experiments are working to learn more about the Higgs and how it behaves — and in the process to maybe reveal something unexpected.

    CERN/ATLAS detector

    “There’s the possibility of not only making very precise measurements of phenomena that will allow us to test our assumptions about the Standard Model, but also gaining an increased scope for new physics that might be just beyond where we’re reaching now,” said Ron Lipton, a Fermilab scientist on the CMS experiment who is coordinating the detector project at national level.

    Of course, the LHC’s high luminosity won’t do much good if the detector isn’t equipped to handle it.

    4
    CMS tracker for HL-LHC

    CERN CMS Tracker for HL-LHC

    See the full article here .

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    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.


    FNAL/MINERvA

    FNAL DAMIC

    FNAL Muon g-2 studio

    FNAL Short-Baseline Near Detector under construction

    FNAL Mu2e solenoid

    Dark Energy Camera [DECam], built at FNAL

    FNAL DUNE Argon tank at SURF

    FNAL/MicrobooNE

    FNAL Don Lincoln

    FNAL/MINOS

    FNAL Cryomodule Testing Facility

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

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  • richardmitnick 1:24 pm on April 20, 2018 Permalink | Reply
    Tags: , , CERN CMS, , , , , ,   

    From FNAL: “CMS experiment at the LHC sees first 2018 collisions” 

    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.

    April 19, 2018
    Cecilia Gerber
    Sergo Jindariani

    Cecilia Gerber and Sergo Jindariani are co-coordinators of the LHC Physics Center at Fermilab.

    After months of winter shutdown, the CMS experiment at the Large Hadron Collider (LHC) is once again seeing collisions and is ready to take data.

    CERN CMS

    CERN CMS Higgs Event

    CERN CMS pre-Higgs Event

    The shutdown months have been very busy for CMS physicists, who used this downtime to improve the performance of the detector by completing upgrades and repairs of detector components. The LHC will continue running until December 2018 and is expected to deliver an additional 50 inverse femtobarns of integrated luminosity to the ATLAS and CMS experiments. This year of data-taking will conclude Run-2, after which the collider and its experiment will go into a two-year long shutdown for further upgrades.

    Run-2 of the LHC has been highly successful, with close to 100 inverse femtobarns of integrated luminosity already delivered to the experiments in 2016 and 2017. These data sets enabled CMS physicists to perform many measurements of Standard Model parameters and searches for new physics. New data will allow CMS to further advance into previously uncharted territory. Physicists from the LHC Physics Center at Fermilab have been deeply involved in the work during the winter shutdown. They are now playing key roles in processing and certification of data recorded by the CMS detector, while looking forward to analyzing the new data sets for a chance to discover new physics.


    This is an event display of one of the early 2018 collisions that took place at the CMS experiment at CERN.

    See the full article here .

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    FNAL Icon

    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.


    FNAL/MINERvA

    FNAL DAMIC

    FNAL Muon g-2 studio

    FNAL Short-Baseline Near Detector under construction

    FNAL Mu2e solenoid

    Dark Energy Camera [DECam], built at FNAL

    FNAL DUNE Argon tank at SURF

    FNAL/MicrobooNE

    FNAL Don Lincoln

    FNAL/MINOS

    FNAL Cryomodule Testing Facility

    FNAL Minos Far Detector

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

    FNAL/NOvA experiment map

    FNAL NOvA Near Detector

    FNAL ICARUS

    FNAL Holometer

     
  • richardmitnick 10:12 am on March 1, 2018 Permalink | Reply
    Tags: , , CERN CMS, , , , , MIT physicists observe electroweak production of same-sign W boson pairs, , ,   

    From MIT: “MIT physicists observe electroweak production of same-sign W boson pairs” 

    MIT News

    MIT Widget

    MIT News

    February 27, 2018
    Scott Morley | Laboratory for Nuclear Science

    1
    Vector-boson scattering processes are characterized by two high-energetic jets in the forward regions of the detector. The Figure shows a significant excess of events in the distribution of the mass of the two tagging jets in yellow, labelled as EW WW. Image: Markus Klute

    In research conducted by a group led by MIT Laboratory for Nuclear Science researcher and associate professor of physics Markus Klute, electroweak productions of same-sign W boson pairs were observed, the first such observation of its kind and a milestone toward precision testing of vector boson scattering (W and Z bosons) at the Large Hadron Collider (LHC).

    LHC

    CERN/LHC Map

    CERN LHC Tunnel

    CERN LHC particles

    The LHC at CERN in Geneva, Switzerland, was proposed in the 1980s as a machine to either find the Higgs boson or discover yet unknown particles or interactions.

    CERN CMS Higgs Event


    CERN ATLAS Higgs Event

    This idea, that the LHC would be able to make a discovery, whatever that might be, is called by theorists No-lose Theorem, and is connected to probing the scattering of W boson pairs at energies above 1 teraelectronvolt (TeV). In 2012, only two years after the first high-energy collision at the LHC, this proposal paid huge dividends when the Higgs boson was discovered by the ATLAS and Compact Muon Solenid (CMS) collaborations.

    According to CERN, the CMS detector at the LHC utilizes a massive solenoid magnet to study everything from the Higgs boson to dark matter to the Standard Model.

    CERN/CMS Detector

    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.

    CMS is capable of generating a magnetic field that is approximately 100,000 times that of Earth. It resides in an underground cavern near Cessy, France, which is northwest of Geneva.

    The main goal of a recent measurement by CMS was to identify W boson pairs with the same sign (W+W+ or W-W-) produced purely via the electroweak interaction and probing the scattering of W bosons. The result does not unveil physics beyond the Standard Model, but this first observation of this process marks a starting point for a field of study to independently test whether the discovered Higgs boson is or is not the particle predicted by Robert Brout, François Englert, and Peter Higgs. It is anticipated that the rapidly growing data sets available at the LHC will further knowledge along these lines. Studies show that the high luminosity LHC will likely allow the direct study of longitudinal W boson scattering.

    “The measurement of vector-boson scattering processes, like the one studied in this paper, is an important test bench of the nature of the Higgs boson, as small deviations from the Standard Model expectation can have a large impact on event rates,” Klute says. “While challenging new physics models, these processes also allow a unique model-independent measurement of Higgs boson couplings to the W and Z boson at the LHC.”

    “The observation of this vector-boson scattering process is an important milestone toward future precision measurements,” Klute says. “These measurements are very challenging experimentally and require theoretical predictions with high precision. Both areas are pushed forward by the published results.”

    The work, while within CMS, was performed by MIT and included Klute, his students Andrew Levin and Xinmei Nui, and research scientist Guillelmo Gomez-Ceballos, along with University of Antwerp colleague Xavier Janssen and his student Jasper Lauwers.

    The work has been published in Physical Review Letters.

    This research was funded with support from U.S. Department of Energy.

    See the full article here .

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    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

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  • richardmitnick 11:31 am on December 20, 2017 Permalink | Reply
    Tags: , , CERN CMS, CMS releases more than one petabyte of open data, , , ,   

    From CERN: “CMS releases more than one petabyte of open data” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    20 Dec 2017
    Corinne Pralavorio

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    A collision event recorded by CMS in 2012 showing a “Higgs candidate”, available on the CERN Open Data portal with the latest release of CMS Open Data. (Image: Tom McCauley/CMS/CERN)

    The CMS Collaboration at CERN have just made public around half of the data collected in 2012 by the CMS detector at the Large Hadron Collider. This release includes sets used to discover the Higgs boson, and is being shared through the CERN Open Data portal.

    This is the third release of high-level CMS Open Data, following the release of 2010 data in 2014, and 2012 data in 2016. This batch contains more than 550 terabytes of proton-proton collision data recorded at a centre-of-mass energy of 8 TeV as well as around 510 petabytes of Monte Carlo simulation data.

    LHC data are complicated and big. CMS researchers have recorded petabytes of data from collisions at the LHC and have so far published hundreds of scientific papers with them. By releasing the data into the public domain, researchers outside the CMS Collaboration have the opportunity to conduct novel research with them.

    “Our data are an important element of the CMS Collaboration’s rich scientific legacy,” says CMS Spokesperson, Joel Butler. “We would like to ensure that they are not only preserved in the long run but are also available to the public, so that both CMS members and external researchers can re-examine them in the future. This is part of our commitment to openness and long-term data preservation.”

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    Animation showing a “Higgs candidate” event, recorded by CMS in 2012 and available on the CERN Open Data portal with the latest release of CMS Open Data. (Image: Tom McCauley and Achintya Rao CMS/CERN)

    Recently, the first two such research papers were published by a team of theorists at MIT interested in performing a measurement CMS scientists had themselves not done: specifically they wanted to measure particular substructures in clusters of particles known as “jets” produced in proton-proton collisions.

    The latest release of CMS Open Data also carries the fascinating possibility of allowing people to repeat the analysis that led to the Higgs discovery by studying the same data used by CMS scientists to announce the particle’s existence in 2012. As a proof of concept, CMS doctoral student Nur Zulaiha Jomhari analysed CMS Open Data and produced plots similar to some of those shown when the Higgs discovery was announced. This analysis is a lot less sophisticated than the official CMS one and is not scrutinised by the wider CMS community of experts, but it demonstrates the potential of CMS Open Data.

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    Left: The official CMS plot for the “Higgs to four leptons” channel, shown on the day of the Higgs discovery announcement. Right: A similar plot produced by Nur Zulaiha Jomhari et al. using CMS Open Data from 2011 and 2012. Although the plots appear similar, the analysis with CMS Open Data uses more data (at 8 TeV and overall) than the official CMS one from the original discovery but is a lot less sophisticated and is not scrutinised by the wider CMS community of experts. (Image: CMS/CERN)

    In addition to the datasets themselves, the CMS Data Preservation and Open Data team has also assembled a comprehensive collection of supplementary materials, including example code for performing relatively simple analyses, as well as metadata such as information on how data were selected and what the LHC’s running conditions were during the time of data collection.

    At the moment, CMS has committed to releasing up to 50% of each year’s recorded data a few years after they were collected, once CMS scientists finish most of their analysis of these datasets. “To see our open data in use outside CMS has been very rewarding,” says Kati Lassila-Perini, the CMS Data Preservation and Open Access co-coordinator. “It has been a great motivation for us and we look forward to continuing our pioneering efforts to release research-quality open data from the LHC in the years to come.”

    Read more about this release in the CMS announcement

    See the full article here.

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    Meet CERN in a variety of places:

    Quantum Diaries
    QuantumDiaries

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

    Quantum Diaries

     
  • richardmitnick 12:10 pm on November 22, 2017 Permalink | Reply
    Tags: , , CERN CMS, , , , Intel, , ,   

    From CERN: “Fermilab joins CERN openlab, works on ‘data reduction’ project with CMS experiment” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    1

    2
    Fermilab Wilson Hall

    Fermilab, the USA’s premier particle physics and accelerator laboratory, has joined CERN openlab as a research member. Researchers from the laboratory will collaborate with members of the CMS experiment and the CERN IT Department on efforts to improve technologies related to ‘physics data reduction’. This work will take place within the framework of an existing CERN openlab project with Intel on ‘big-data analytics’.

    CERN/CMS Detector

    ‘Physics data reduction’ plays a vital role in ensuring researchers are able to gain valuable insights from the vast amounts of particle-collision data produced by high-energy physics experiments, such as the CMS experiment on CERN’s Large Hadron Collider (LHC).

    LHC

    CERN/LHC Map

    CERN LHC Tunnel

    CERN LHC particles

    The project’s goal is to develop a new system — using industry-standard big-data tools — for filtering many petabytes of heterogeneous collision data to create manageable, but rich, datasets of a few terabytes for analysis. Using current systems, this kind of targeted data reduction can often take weeks; but the aim of the project is to be able to achieve this in a matter of hours.

    “Time is critical in analysing the ever-increasing volumes of LHC data,”says Oliver Gutsche, a Fermilab scientist working at the CMS experiment. “I am excited about the prospects CERN openlab brings to the table: systems that could enable us to perform analysis much faster and with much less effort and resources.” Gutsche and his colleagues will explore methods of ensuring efficient access to the data from the experiment. For this, they will investigate techniques based on Apache Spark, a popular open-source software platform for distributed processing of very large data sets on computer clusters built from commodity hardware. “The success of this project will have a large impact on the way analysis is conducted, allowing more optimised results to be produced in far less time,” says Matteo Cremonesi, a research associate at Fermilab. “I am really looking forward to using the new open-source tools; they will be a game changer for the overall scientific process in high-energy physics.”

    The team plans to first create a prototype of the system, capable of processing 1 PB of data with about 1000 computer cores. Based on current projections, this is about 1/20th of the scale of the final system that would be needed to handle the data produced when the High-Luminosity LHC comes online in 2026.

    Using this prototype, it should be possible to produce a benchmark (or ‘reference workload’) that can be used evaluate the optimum configuration of both hardware and software for the data-reduction system.

    “This kind of work, investigating big-data analytics techniques is vital for high-energy physics — both in terms of physics data and data from industrial control systems on the LHC,” says Maria Girone, CERN openlab CTO. “However, these investigations also potentially have far-reaching impact for a range of other disciplines. For example, this CERN openlab project with Intel is also exploring the use of these kinds of analytics techniques for healthcare data.”

    “Intel is proud of the work it has done in enabling the high-energy physics community to adopt the latest technologies for high-performance computing, data analytics, and machine learning — and reap the benefits. CERN openlab’s project on big-data analytics is one of the strategic endeavours to which Intel has been contributing,” says Stephan Gillich, Intel Deutschland’s director of technical computing for Europe, the Middle East, and Africa. “The possibility of extending the CERN openlab collaboration to include Fermilab, one of the world’s leading research centres, is further proof of the scientific relevance and success of this private-public partnership.”

    See the full article here.

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    About CERN openlab

    CERN openlab is a unique public-private partnership that accelerates the development of cutting-edge solutions for the worldwide LHC community and wider scientific research. Through CERN openlab, CERN collaborates with leading ICT companies and research institutes.

    Within this framework, CERN provides access to its complex IT infrastructure and its engineering experience, in some cases even extended to collaborating institutes worldwide. Testing in CERN’s demanding environment provides the ICT industry partners with valuable feedback on their products while allowing CERN to assess the merits of new technologies in their early stages of development for possible future use. This framework also offers a neutral ground for carrying out advanced R&D with more than one company.

    CERN openlab was created in 2001 (link is external) and is now in the phase V (2015-2017). This phase tackles ambitious challenges covering the most critical needs of IT infrastructures in domains such as data acquisition, computing platforms, data storage architectures, compute provisioning and management, networks and communication, and data analytics.

    Meet CERN in a variety of places:

    Quantum Diaries
    QuantumDiaries

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

    Quantum Diaries

     
  • richardmitnick 12:56 pm on September 29, 2017 Permalink | Reply
    Tags: , CERN CMS, , CERN Open Data Portal, ,   

    From MIT: “First open-access data from large collider confirm subatomic particle patterns” 

    MIT News

    MIT Widget

    MIT News

    September 29, 2017
    Jennifer Chu

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    The Compact Muon Solenoid is a general-purpose detector at the Large Hadron Collider. Image courtesy of CERN

    LHC

    CERN/LHC Map

    CERN LHC Tunnel

    CERN LHC particles

    In November of 2014, in a first, unexpected move for the field of particle physics, the Compact Muon Solenoid (CMS) experiment — one of the main detectors in the world’s largest particle accelerator, the Large Hadron Collider — released to the public an immense amount of data, through a website called the CERN Open Data Portal.

    The data, recorded and processed throughout the year 2010, amounted to about 29 terabytes of information, yielded from 300 million individual collisions of high-energy protons within the CMS detector. The sharing of these data marked the first time any major particle collider experiment had released such an information cache to the general public.

    A new study by Jesse Thaler, an associate professor of physics at MIT and a long-time advocate for open access in particle physics, and his colleagues now demonstrates the scientific value of this move. In a paper published in Physical Review Letters, the researchers used the CMS data to reveal, for the first time, a universal feature within jets of subatomic particles, which are produced when high-energy protons collide. Their effort represents the first independent, published analysis of the CMS open data.

    “In our field of particle physics, there isn’t the tradition of making data public,” says Thaler. “To actually get data publicly with no other restrictions — that’s unprecedented.”

    Part of the reason groups at the Large Hadron Collider and other particle accelerators have kept proprietary hold over their data is the concern that such data could be misinterpreted by people who may not have a complete understanding of the physical detectors and how their various complex properties may influence the data produced.

    “The worry was, if you made the data public, then you would have people claiming evidence for new physics when actually it was just a glitch in how the detector was operating,” Thaler says. “I think it was believed that no one could come from the outside and do those corrections properly, and that some rogue analyst could claim existence of something that wasn’t really there.”

    “This is a resource that we now have, which is new in our field,” Thaler adds. “I think there was a reluctance to try to dig into it, because it was hard. But our work here shows that we can understand in general how to use this open data, that it has scientific value, and that this can be a stepping stone to future analysis of more exotic possibilities.”

    Thaler’s co-authors are Andrew Larkoski of Reed College, Simone Marzani of the State University of New York at Buffalo, and Aashish Tripathee and Wei Xue of MIT’s Center for Theoretical Physics and Laboratory for Nuclear Science.

    Seeing fractals in jets

    When the CMS collaboration publicly released its data in 2014, Thaler sought to apply new theoretical ideas to analyze the information. His goal was to use novel methods to study jets produced from the high-energy collision of protons.

    Protons are essentially accumulations of even smaller subatomic particles called quarks and gluons, which are bound together by interactions known in physics parlance as the strong force. One feature of the strong force that has been known to physicists since the 1970s describes the way in which quarks and gluons repeatedly split and divide in the aftermath of a high-energy collision.

    This feature can be used to predict the energy imparted to each particle as it cleaves from a mother quark or gluon. In particular, physicists can use an equation, known as an evolution equation or splitting function, to predict the pattern of particles that spray out from an initial collision, and therefore the overall structure of the jet produced.

    “It’s this fractal-like process that describes how jets are formed,” Thaler says. “But when you look at a jet in reality, it’s really messy. How do you go from this messy, chaotic jet you’re seeing to the fundamental governing rule or equation that generated that jet? It’s a universal feature, and yet it has never directly been seen in the jet that’s measured.”

    Collider legacy

    In 2014, the CMS released a preprocessed form of the detector’s 2010 raw data that contained an exhaustive listing of “particle flow candidates,” or the types of subatomic particles that are most likely to have been released, given the energies measured in the detector after a collision.

    The following year, Thaler published a theoretical paper with Larkoski and Marzani, proposing a strategy to more fully understand a complicated jet in a way that revealed the fundamental evolution equation governing its structure.

    “This idea had not existed before,” Thaler says. “That you could distill the messiness of the jet into a pattern, and that pattern would match beautifully onto that equation — this is what we found when we applied this method to the CMS data.”

    To apply his theoretical idea, Thaler examined 750,000 individual jets that were produced from proton collisions within the CMS open data. He looked to see whether the pattern of particles in those jets matched with what the evolution equation predicted, given the energies released from their respective collisions.

    Taking each collision one by one, his team looked at the most prominent jet produced and used previously developed algorithms to trace back and disentangle the energies emitted as particles cleaved again and again. The primary analysis work was carried out by Tripathee, as part of his MIT bachelor’s thesis, and by Xue.

    “We wanted to see how this jet came from smaller pieces,” Thaler says. “The equation is telling you how energy is shared when things split, and we found when you look at a jet and measure how much energy is shared when they split, they’re the same thing.”

    The team was able to reveal the splitting function, or evolution equation, by combining information from all 750,000 jets they studied, showing that the equation — a fundamental feature of the strong force — can indeed predict the overall structure of a jet and the energies of particles produced from the collision of two protons.

    While this may not generally be a surprise to most physicists, the study represents the first time this equation has been seen so clearly in experimental data.

    “No one doubts this equation, but we were able to expose it in a new way,” Thaler says. “This is a clean verification that things behave the way you’d expect. And it gives us confidence that we can use this kind of open data for future analyses.”

    Thaler hopes his and others’ analysis of the CMS open data will spur other large particle physics experiments to release similar information, in part to preserve their legacies.

    “Colliders are big endeavors,” Thaler says. “These are unique datasets, and we need to make sure there’s a mechanism to archive that information in order to potentially make discoveries down the line using old data, because our theoretical understanding changes over time. Public access is a stepping stone to making sure this data is available for future use.”

    This research was supported, in part, by the MIT Charles E. Reed Faculty Initiatives Fund, the MIT Undergraduate Research Opportunities Program, the U.S. Department of Energy, and the National Science Foundation.

    See the full article here .

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    MIT Seal

    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

    MIT Campus

     
  • richardmitnick 11:11 am on May 24, 2017 Permalink | Reply
    Tags: , , CERN CMS, , , , Our failure in resolve,   

    From FNAL: “Fermilab scientists set upper limit for Higgs boson mass” 

    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.

    In 1977, theoretical physicists at Fermilab — Ben Lee and Chris Quigg, along with Hank Thacker — published a paper setting an upper limit for the mass of the Higgs boson. This calculation helped guide the design of the Large Hadron Collider by setting the energy scale necessary for it to discover the particle. The Large Hadron Collider turned on in 2008, and in 2012, the LHC’s ATLAS and CMS discovered the long-sought Higgs boson — 35 years after the seminal paper.

    1

    CERN CMS Higgs Event


    CERN/CMS Detector


    CERN ATLAS Higgs Event


    CERN/ATLAS detector

    Where it all started:

    FNAL Tevatron

    FNAL/Tevatron map


    FNAL/Tevatron DZero detector


    FNAL/Tevatron CDF detector

    Where we failed and handed it to Europe:

    3
    Sight of the planned Superconducting Super Collider, in the vicinity of Waxahachie, Texas. Cancelled by our idiot Congress under Bill Clinton in 1993. We could have had it all.

    See the full article here .

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    FNAL Icon
    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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