From FNAL: “Photons continue to enlighten physicists”

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.

December 13, 2017
Andy Beretvas
Alessandra Lucà

You may be familiar with particles of light, called photons. Physicists give the name “prompt photons” to those that are produced by two particles smashing together — hard collisions — as contrasted with those resulting from the decay of other particles. The Tevatron produced prompt photons by the hard collisions between protons and antiprotons.

Knowing the likelihood that proton-antiproton collisions will produce prompt photons tells us something about the proton’s components, which are called quarks and gluons. In particular, we can learn about the density of quarks and gluons inside the colliding protons and get a better grasp on how they fragment into photons. These ingredients are all described in a theory called perturbative quantum chromodynamics.

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The cross section is presented as a function of the transverse energy of the photon.

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This plot compares three models — Pythia 6.216, Sherpa 1.4.1 and MCFM 6.8 — to the data.

Prompt photons at hadron colliders constitute an important test of perturbative quantum chromodynamics (pQCD), and may also be found in signatures of new physics processes. A precise measurement of prompt photon production is important to probe theoretical models, as well as to gain a better understanding of final states that contain energetic photons.

CDF physicists used the full Tevatron Run II data set, which contained 2.1 million collision events in the selected sample, to measure the prompt photons’ energies.

FNAL/Tevatron CDF detector

The researchers were particularly interested in the energy they carried in a direction perpendicular to the colliding beams, a property called transverse energy.

The photons’ transverse energy tells you something about the process that produced it. Photons with less than 100 GeV of transverse energy were generated primarily by quarks and gluons scattering off each other. At higher energies, the dominant process was the annihilation of a quark with its antimatter counterpart.

CDF conducted a similar study to this one in 2009. An important part of the measurement is that the photons should be isolated (the energy deposited near the photon is small). This time, a larger data set meant scientists could study a larger range of transverse photon energy, from 30 to 500 GeV. Moreover, a different statistical technique has been developed to better identify prompt photons; their identification is very challenging because of the huge background coming from other particles (mostly hadrons).

The results are presented in the first figure: The likelihood of proton-antiproton collisions producing a prompt photon decreases with increasing transverse energy. Note the data covers six orders of magnitude. This provides a challenge for theorists to come up with models that predicts this behavior correctly over so large a range.

Over the full range, data shows good agreement with the MCFM prediction. This model is a next-to-leading order pQCD calculation developed by Fermilab physicists John Campbell, Keith Ellis, Walter Giele and Ciaran Williams.

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
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From FNAL: “CDF publishes 700 papers”

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 30, 2017
David Toback

Scientist David Toback, professor at Texas A&M University and the Mitchell Institute for Fundamental Physics and Astronomy, is co-spokesperson of the CDF experiment.

The year 2017 is full of important Fermilab milestones. Fermilab’s 50th anniversary. The 25th anniversary of the lab’s first website. The 40th anniversary of the discovery of the bottom quark.

FNAL/Tevatron CDF detector

The Collider Detector at Fermilab, CDF, recently celebrated an important milestone — perhaps not as lofty or storied as the above anniversaries, but a proud moment nonetheless: On May 30, our 700th paper was officially published in Phys. Rev. D. The publication, which focuses on the production of D meson in the unique Tevatron environment, was led by an Italian student working with both American and Italian collaborators. It was a fitting way to ring in this milestone and encouraged us to reflect on the past 37 years of the collaboration.

CDF was created as a United States-Italy-Japan collaboration. Today the pursuit of particle physics is unthinkable without global cooperation, but in 1980, when CDF started as a three-country endeavor, it was the primary vision of director Robert Wilson for the lab to go worldwide. CDF has included scientists from more than a dozen countries over the years, and would include more than 600 physicists at its peak.

A storied history. With 700 publications, it is hard to choose only a few among so many highlights. Perhaps it is obvious to start with the 1995 co-discovery of the top quark. More than 20 years later, some CDF measurements, such as the measurement of the top mass, remain among the most sensitive in the world. Another important paper detailed the discovery of the quick-change behavior of the Bs meson, which switches between matter and antimatter 3 trillion times a second and was the first observation of CP violation in the b quark system. CDF’s measurement of the mass of the W boson is still the most precise on record. Perhaps equally important is that the production of these papers helped almost 640 individuals gain their Ph.D. using CDF data.

A curious set of characters and stories. While most people know that current Fermilab Director Nigel Lockyer is a former CDF spokesperson, the current spokespersons have fun stories as well. A fun fact about CDF today is that its longevity has produced the remarkable occurrence that both spokespersons were Ph.D. students on the experiment. Giorgio Chiarelli, INFN-Pisa, was the second student to receive his Ph.D., and yours truly was the 159th. Equally amusing is that Chiarelli’s advisor, Giorgio Bellettini (who has been on CDF since the very beginning), was a two-time co-spokesperson himself and just handed off the baton to his student on June 1.

Looking forward: With 37 years in the books, the road ahead is clearly shorter than the one in the past. However, even as the Large Hadron Collider goes strong, data collected from Tevatron collisions continues to add to the book on particle physics, and the experiment is still producing results. CDF looks forward to many important and competitive legacy measurements, including those of the top mass, the W mass, sin2θ­W, and the forward-backward asymmetry of top quark pairs. We retain our emphasis on getting the papers out.

Congratulations CDF, and to members past and present, on your 700th paper and the many accomplishments you’ve logged along the way!

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CDF collaboration. Photo: Cindy Arnold

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.

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From BNL: “Brookhaven Lab’s Scientific Data and Computing Center Reaches 100 Petabytes of Recorded Data”

Brookhaven Lab

Ariana Tantillo
atantillo@bnl.gov

Total reflects 17 years of experimental physics data collected by scientists to understand the fundamental nature of matter and the basic forces that shape our universe.

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(Back row) Ognian Novakov, Christopher Pinkenburg, Jérôme Lauret, Eric Lançon, (front row) Tim Chou, David Yu, Guangwei Che, and Shigeki Misawa at Brookhaven Lab’s Scientific Data and Computing Center, which houses the Oracle StorageTek tape storage system where experimental data are recorded.

Imagine storing approximately 1300 years’ worth of HDTV video, nearly six million movies, or the entire written works of humankind in all languages since the start of recorded history—twice over. Each of these quantities is equivalent to 100 petabytes of data: the amount of data now recorded by the Relativistic Heavy Ion Collider (RHIC) and ATLAS Computing Facility (RACF) Mass Storage Service, part of the Scientific Data and Computing Center (SDCC) at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory. One petabyte is defined as 10245 bytes, or 1,125,899,906,842,624 bytes, of data.

“This is a major milestone for SDCC, as it reflects nearly two decades of scientific research for the RHIC nuclear physics and ATLAS particle physics experiments, including the contributions of thousands of scientists and engineers,” said Brookhaven Lab technology architect David Yu, who leads the SDCC’s Mass Storage Group.

SDCC is at the core of a global computing network connecting more than 2,500 researchers around the world with data from the STAR and PHENIX experiments at RHIC—a DOE Office of Science User Facility at Brookhaven—and the ATLAS experiment at the Large Hadron Collider (LHC) in Europe.

BNL/RHIC Star Detector

BNL/RHIC PHENIX

CERN/ATLAS detector

In these particle collision experiments, scientists recreate conditions that existed just after the Big Bang, with the goal of understanding the fundamental forces of nature—gravitational, electromagnetic, strong nuclear, and weak nuclear—and the basic structure of matter, energy, space, and time.

Big Data Revolution

The RHIC and ATLAS experiments are part of the big data revolution.

BNL RHIC Campus


BNL/RHIC

These experiments involve collecting extremely large datasets that reduce statistical uncertainty to make high-precision measurements and search for extremely rare processes and particles.

For example, only one Higgs boson—an elementary particle whose energy field is thought to give mass to all the other elementary particles—is produced for every billion proton-proton collisions at the LHC.

CERN CMS Higgs Event


CERN/CMS Detector

CERN ATLAS Higgs Event

More, once produced, the Higgs boson almost immediately decays into other particles. So detecting the particle is a rare event, with around one trillion collisions required to detect a single instance. When scientists first discovered the Higgs boson at the LHC in 2012, they observed about 20 instances, recording and analyzing more than 300 trillion collisions to confirm the particle’s discovery.

LHC

CERN/LHC Map

CERN LHC Tunnel

CERN LHC particles

At the end of 2016, the ATLAS collaboration released its first measurement of the mass of the W boson particle (another elementary particle that, together with the Z boson, is responsible for the weak nuclear force). This measurement, which is based on a sample of 15 million W boson candidates collected at LHC in 2011, has a relative precision of 240 parts per million (ppm)—a result that matches the best single-experiment measurement announced in 2007 by the Collider Detector at Fermilab collaboration, whose measurement is based on several years’ worth of collected data. A highly precise measurement is important because a deviation from the mass predicted by the Standard Model could point to new physics. More data samples are required to achieve the level of accuracy (80 ppm) that scientists need to significantly test this model.

The volume of data collected by these experiments will grow significantly in the near future as new accelerator programs deliver higher-intensity beams. The LHC will be upgraded to increase its luminosity (rate of collisions) by a factor of 10. This High-Luminosity LHC, which should be operational by 2025, will provide a unique opportunity for particle physicists to look for new and unexpected phenomena within the exabytes (one exabyte equals 1000 petabytes) of data that will be collected.

Data archiving is the first step in making available the results from such experiments. Thousands of physicists then need to calibrate and analyze the archived data and compare the data to simulations. To this end, computational scientists, computer scientists, and mathematicians in Brookhaven Lab’s Computational Science Initiative, which encompasses SDCC, are developing programming tools, numerical models, and data-mining algorithms. Part of SDCC’s mission is to provide computing and networking resources in support of these activities.

A Data Storage, Computing, and Networking Infrastructure

Housed inside SDCC are more than 60,000 computing cores, 250 computer racks, and tape libraries capable of holding up to 90,000 magnetic storage tape cartridges that are used to store, process, analyze, and distribute the experimental data. The facility provides approximately 90 percent of the computing capacity for analyzing data from the STAR and PHENIX experiments, and serves as the largest of the 12 Tier 1 computing centers worldwide that support the ATLAS experiment. As a Tier 1 center, SDCC contributes nearly 23 percent of the total computing and storage capacity for the ATLAS experiment and delivers approximately 200 terabytes of data (picture 62 million photos) per day to more than 100 data centers globally.

At SDCC, the High Performance Storage System (HPSS) has been providing mass storage services to the RHIC and LHC experiments since 1997 and 2006, respectively. This data archiving and retrieval software, developed by IBM and several DOE national laboratories, manages petabytes of data on disk and in robot-controlled tape libraries. Contained within the libraries are magnetic tape cartridges that encode the data and tape drives that read and write the data. Robotic arms load the cartridges into the drives and unload them upon request.

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Inside one of the automated tape libraries at the Scientific Data and Computing Center (SDCC), Eric Lançon, director of SDCC, holds a magnetic tape cartridge. When scientists need data, a robotic arm (the piece of equipment in front of Lançon) retrieves the relevant cartridges from their slots and loads them into drives in the back of the library.

When ranked by the volume of data stored in a single HPSS, Brookhaven’s system is the second largest in the nation and the fourth largest in the world. Currently, the RACF operates nine Oracle robotic tape libraries that constitute the largest Oracle tape storage system in the New York tri-state area. Contained within this system are nearly 70,000 active cartridges with capacities ranging from 800 gigabytes to 8.5 terabytes, and more than 100 tape drives. As the volume of scientific data to be stored increases, more libraries, tapes, and drives can be added accordingly. In 2006, this scalability was exercised when HPSS was expanded to accommodate data from the ATLAS experiment at LHC.

“The HPSS system was deployed in the late 1990s, when the RHIC accelerator was coming on line. It allowed data from RHIC experiments to be transmitted via network to the data center for storage—a relatively new idea at the time,” said Shigeki Misawa, manager of Mass Storage and General Services at Brookhaven Lab. Misawa played a key role in the initial evaluation and configuration of HPSS, and has guided the system through significant changes in hardware (network equipment, storage systems, and servers) and operational requirements (tape drive read/write rate, magnetic tape cartridge capacity, and data transfer speed). “Prior to this system, data was recorded on magnetic tape at the experiment and physically moved to the data center,” he continued.

Over the years, SDCC’s HPSS has been augmented with a suite of optimization and monitoring tools developed at Brookhaven Lab. One of these tools is David Yu’s scheduling software that optimizes the retrieval of massive amounts of data from tape storage. Another, developed by Jérôme Lauret, software and computing project leader for the STAR experiment, is software for organizing multiple user requests to retrieve data more efficiently.

Engineers in the Mass Storage Group—including Tim Chou, Guangwei Che, and Ognian Novakov—have created other software tools customized for Brookhaven Lab’s computing environment to enhance data management and operation abilities and to improve the effectiveness of equipment usage.

STAR experiment scientists have demonstrated the capabilities of SDCC’s enhanced HPSS, retrieving more than 4,000 files per hour (a rate of 6,000 gigabytes per hour) while using a third of HPSS resources. On the data archiving side, HPSS can store data in excess of five gigabytes per second.

As demand for mass data storage spreads across Brookhaven, access to HPSS is being extended to other research groups. In the future, SDCC is expected to provide centralized mass storage services to multi-experiment facilities, such as the Center for Functional Nanomaterials and the National Synchrotron Light Source II—two more DOE Office of Science User Facilities at Brookhaven.

“The tape library system of SDCC is a clear asset for Brookhaven’s current and upcoming big data science programs,” said SDCC Director Eric Lançon. “Our expertise in the field of data archiving is acknowledged worldwide.”

See the full article here .

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

FNAL II photo

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FNAL Art Image by Angela Gonzales

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

June 13, 2017
Troy Rummler

The Standard Model of physics makes some not-so-standard predictions about our universe.

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.

Fermilab has pioneered extremely precise technologies that put these theories to the test, including the CDF experiment, which confirmed in 2006 that, yes, a Bs (pronounced “B sub s”) meson actually does switch between matter and antimatter 3 trillion times a second.

FNAL Tevatron

FNAL/Tevatron map


FNAL/Tevatron DZero detector


FNAL/Tevatron CDF detector

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.

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From FNAL: “CDF rounds up the final meson”

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 8, 2017
Troy Rummler

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FNAL Tevatron CDF

On March 5, 1998, Fermilab announced it had discovered the Bc meson. This particle was the last of 15 unexcited quark-antiquark pairs to be discovered. The first one had been discovered 50 years earlier in cosmic rays, but this flighty character, which lives just 0.46 picoseconds, could be found only as a product of powerful, high-energy particle collisions.

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.

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From FNAL: ” CDF makes first use of silicon vertex detectors in a hadron collider environment”

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 3, 2017
Troy Rummler

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In the early 1990s, the CDF collaboration installed the world’s first silicon detector in a hadron collider. Silicon detectors are now a mainstay for tracking short-lived particles very close to the collision point, but for years they were thought too fragile and too difficult to work with for anything besides small-scale experiments. CDF collaborators also developed a hardware system that could use the vast amount of data from the silicon detector in real time to detect displaced vertices, which enabled them to record world-leading-sized samples of beauty hadrons. Fermilab collaborators Aldo Menzione and Luciano Ristori developed CDF’s silicon vertex detector and were awarded the 2009 Panofsky Prize for their work, one of the highest honors a physicist can receive.

FNAL Tevatron

FNAL/Tevatron map


FNAL/Tevatron DZero detector


FNAL/Tevatron CDF detector

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.

#accelerator-science, #basic-research, #fnal-cdf, #hep, #particle-accelerators, #particle-physics

From FNAL: “CDF can’t stop being charming”

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.

September 8, 2016
Jeffrey Appel

FNAL/Tevatron map
FNAL/Tevatron map

FNAL/Tevatron CDF detector
FNAL/Tevatron CDF detector

Good news: there is a theory to describe the strong interaction, the interactions that bind the constituents of protons and neutrons together and create the strong force. Bad news: Calculations using the theory can be made in only a limited selection of natural phenomena.

Quantitative predictions for interactions beyond that subset depend on measurements. This can be either for direct use or to help guide the theory about the inputs used in calculations, such as the distributions of the quark and gluon constituents inside protons and neutrons. Using the production of particles containing heavy charm and bottom quarks helps especially with gluon distributions.

CDF is now reporting new measurements of the rate of production at the Tevatron of D+ mesons, which contain charm quarks. Furthermore, the new measurements are made in the region where the D+ mesons have the smallest momentum transverse to the incident beams. This is the region that is the hardest to calculate using the theory of strong interactions and has never been explored in proton-antiproton collisions.

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This plot shows the measures, in bins of momentum transverse to incident protons, of the average probability of producing a D+ meson at the Tevatron. Shown as bands are the averages predicted in the same bins by the latest theoretical calculations.

To probe such small transverse momenta, CDF physicists examined all types of interactions of the incoming protons and antiprotons, not just those selected to study rare occurrences.

The results of this new analysis appear in the figure. The measurements lie within the band of uncertainty of the theoretical predictions. Using the results here, theorists can reduce the size of the band of uncertainty. They might also be able to improve the general trend of the predictions to agree better with the trends in the measurements.

This measurement is an example of CDF’s continuing effort to produce unique and useful results that complement and supplement those of the LHC. These help improve our understanding of the fundamental forces of nature.

Learn more.

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.

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