SMU scientists celebrate Nobel Prize for Higgs discovery

CERN

SMU scientists celebrate Nobel Prize for Higgs discovery

Particle collision from the ATLAS ExperimentSMU’s experimental physics group played a pivotal role in discovering the Higgs boson — the particle that proves the theory for which two scientists have received the 2013 Nobel Prize in Physics.

The Royal Swedish Academy of Sciences today awarded the Nobel Prize to theorists Peter W. Higgs and François Englert to recognize their work developing the theory of what is now known as the Higgs field, which gives elementary particles mass. U.S. scientists played a significant role in advancing the theory and in discovering the particle that proves the existence of the Higgs field, the Higgs boson.

The Nobel citation recognizes Higgs and Englert “for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN’s Large Hadron Collider.”

“A scientist may test out a thousand different ideas over the course of a career. If you’re fortunate, you get to experiment with one that works,” says SMU physicist Ryszard Stroynowski, a principal investigator in the search for the Higgs boson. As the leader of an SMU Department of Physics team working on the experiment, Stroynowski served as U.S. coordinator for the ATLAS Experiment’s Liquid Argon Calorimeter, which measures energy from the particles created by proton collisions.

The University’s experimental physics group has been involved since 1994 and is a major contributor to the research, the heart of which is the Large Hadron Collider particle accelerator on the border with Switzerland and France.

Preliminary discovery results were announced July 4, 2012 at CERN, the European Organization for Nuclear Research, near Geneva, Switzerland, and at the International Conference of High Energy Physics in Melbourne, Australia.

• Several contributors from SMU have made their mark on the project at various stages, including current Department of Physics faculty members Ryszard Stroynowski, Jingbo Ye, Robert Kehoe and Stephen Sekula. Faculty members Pavel Nadolsky and Fred Olness performed theoretical calculations used in various aspects of data analysis.

• University postdoctoral fellows on the ATLAS Experiment have included Julia Hoffmann, David Joffe, Ana Firan, Haleh Hadavand, Peter Renkel, Aidan Randle-Conde, Daniel Goldin and Sami Kama.

• SMU has awarded eight Ph.D. and seven M.S. degrees to students who performed advanced work on ATLAS, including Ryan Rios, Rozmin Daya, Renat Ishmukhametov, Tingting Cao, Kamile Dindar, Pavel Zarzhitsky and Azzedin Kasmi.

• Significant contributions to ATLAS have also been made by SMU faculty members in the Department of Physics’ Optoelectronics Lab, including Tiankuan Liu, Annie Xiang and Datao Gong.

“The discovery of the Higgs is a great achievement, confirming an idea that will require rewriting of the textbooks,” Stroynowski says. “But there is much more to be learned from the LHC and from ATLAS data in the next few years. We look forward to continuing this work.”

> Read the full story from SMU News

October 8, 2013|News, Research|

Research Spotlight: CERN scientists close in on Higgs boson

An event showing four muons (red tracks) from a proton-proton collision in ATLAS. This event is consistent with two Z particles decaying into two muons each. Such events are produced by Standard Model processes without Higgs particles. They are also a possible signature for Higgs particle production, but many events must be analyzed together in order to tell if there is a Higgs signal. (Image courtesy of CERN.)

In a giant game of hide and seek, physicists say there are indications they finally may have found evidence of the long sought after fundamental particle called the Higgs boson.

Researchers at Switzerland-based CERN, the largest high-energy physics experiment in the world, have been seeking the Higgs boson since it was theorized in the 1960s. The so-called “God” particle is believed to play a fundamental role in solving the important mystery of why matter has mass.

Thousands of scientists from around the world seek evidence of the Higgs particle through experiments at CERN’s Large Hadron Collider. The researchers analyze a flood of electronic data streaming from the breakup of speeding protons colliding in the massive particle accelerator. Scientists on Tuesday announced in a seminar held at CERN that they’ve found hints of the Higgs.

SMU physicist Ryszard Stroynowski“Now we have a strong indication, but not yet a confirmation, of a discovery,” said SMU physicist Ryszard Stroynowski (left), the leader of SMU’s team of scientists working on the experiment.

Theorists have predicted that some subatomic particles gain mass by interacting with other particles called Higgs bosons. The Higgs boson is the only undiscovered part of the Standard Model of physics, which describes the basic building blocks of matter and their interactions.

Higgs bosons, if they exist, are short-lived and can decay in many different ways. Just as a vending machine might return the same amount of change using different combinations of coins, the Higgs can decay into different combinations of particles. Discovery relies on observing statistically significant excesses of the particles into which they decay rather than observing the Higgs itself.

“If indeed we are able to confirm sighting of the Higgs in the months ahead, this clearly focuses our future studies,” said Stroynowski, a professor in the SMU Department of Physics. “Now by the middle of next year we’ll know for sure if this particle exists and we can begin to study its properties. This is a very big step in the understanding of particle physics.”

Besides Stroynowski, the SMU team of researchers includes three other Physics Department faculty: Jingbo YeRobert Kehoe and Stephen Sekula, six postdoctoral fellows and five graduate students. Main contributions to the new analysis of the data were made by postdoctoral researcher Julia Hoffman and graduate student Ryan Rios.

Others in the department who have contributed include former postdoctoral fellow David Joffe, now an assistant professor at Kennesaw State University, graduate students Renat Ishmukhametov and Rozmin Daya and theoretical faculty Fredrick Olness and Pavel Nadolsky.

Stroynowski, Hoffman, and Rios are among the more than 70 scientists whose work directly contributed to the conference papers reporting the findings, said Olness, a professor and chairman of the SMU Department of Physics. While thousands of scientists worldwide participated directly and indirectly in the experiments, SMU is one of only a few U.S. universities whose scientists are named among the 70 researchers directly cited on one of the three conference papers.

“SMU’s role in the LHC experiments provides our students a chance to participate in pioneering discoveries,” Olness said. “SMU students helped build the ATLAS detector, they were in the control room when the experiment started up, and they contributed to the analysis. The results presented today are historic, and they will help shape our view of the matter and forces that comprise our universe; SMU students have played a role in this achievement.”

SMU's Ryszard Stroynowski and Ryan Rios

In Fondren Science Building, physicist and SMU Physics Professor Ryszard Stroynowski and physics graduate student Ryan Rios discuss the Higgs boson after viewing a CERN web cast Tuesday announcing evidence of the Higgs. (Photo by Hillsman S. Jackson.)

Discovering the type of Higgs boson predicted in the Standard Model would confirm a theory first put forward in the 1960s.

“This year, the LHC has come roaring into the front of the hunt for the Higgs boson and may be poised to either identify it, or refute its existence, in the coming months,” said Kehoe, associate professor in the SMU Department of Physics. “As I like to tell my students learning modern physics, ‘You still live in a world in which we do not know for sure the mechanism breaking the symmetry between electromagnetic and weak interactions. That world may be soon to change forever. We may soon see a truly new thing.’”

– Written by Margaret Allen

> Read the full story at the SMU Research blog

December 14, 2011|News|

Research Spotlight: SMU physicist earns DOE Early Career Award

SMU physicist Pavel NadolskySMU physicist Pavel Nadolsky will receive $750,000 over five years to fund his work in modeling particle interactions through a new program administered by the Office of Science, U.S. Department of Energy (DOE).

Nadolsky, assistant professor of theoretical physics in SMU’s Dedman College, received the grant for his integrated analysis of particle interactions created by hadron colliders. He was one of 69 researchers chosen through peer review by scientific experts to participate in the DOE’s new Early Career Research Program. About 1,750 applicants submitted proposals.

Early Career Scientists receive funding under the American Recovery and Reinvestment Act of 2009 in an effort “to bolster the nation’s scientific workforce by providing support to exceptional researchers during the crucial early career years, when many scientists do their most formative work,” according to a DOE statement.

Nadolsky works with an SMU team of postdoctoral research associates and graduate students to model hypothetical interactions of subatomic particles for the biggest physics experiment in history: the Large Hadron Collider (LHC) near Geneva, Switzerland.

The LHC became fully operational on March 30, 2010, and the high-speed, high-energy particle collisions it creates will allow physicists to recreate conditions at the origin of the universe – and possibly discover the mechanisms that cause particles in space to acquire their differences in mass.

As part of the effort to identify theoretical new particles such as the Higgs boson, Nadolsky develops highly detailed computer simulations both of known particle interactions and of the expected tiny deviations that LHC researchers hope to discover. Each collision produces a staggering amount of raw information, and the most useful bits are few and far between: Out of 40 million events per second, the researchers may be looking for as few as 10 events a year.

“The phenomena we’re looking for will be buried under a lot of known particles produced by ordinary means,” Nadolsky says. “Our task is to produce the most accurate models possible of known interactions, so we can recognize the interactions that deviate, and why.”

Without such models, identifying new events at the LHC would be difficult, if not impossible, he adds.

> Read more from the SMU Research blog

June 1, 2010|For the Record, Research|

Research Spotlight: The tiny circuit that could

Inside the LHC tunnel during constructionImagine a tiny integrated circuit so small it must be viewed through a microscope, but so powerful, fast and sturdy it can routinely transmit huge amounts of data at high speed in a highly radioactive environment, where temperatures might fall below an unimaginable 300 degrees F.

Yet despite those challenges, the circuit must dissipate very little heat and – because its location makes routine maintenance impossible – it must be highly reliable. An SMU team of physicists led by Associate Professor of Physics Jingbo Ye not only imagined it – they designed it.

The miniscule SMU link-on-chip (LOC) serializer was designed for ATLAS, which is the largest particle detector in the Large Hadron Collider (LHC) – a massive, high-tech tunnel about 100 meters underground. Within the LHC’s 17-mile-long ring, protons traveling at high energy are smashed together and broken apart so physicists worldwide can analyze the resulting particle shower detailed in a flood of electronic data.

The data transmit from the LHC via a tiny serializer circuit enabling electronic readouts. Physicists analyze the data to discover answers to unsolved scientific mysteries such as the Big Bang, dark matter, black holes, the nature of the universe and the Higgs particle that gives mass to quarks and electrons. SMU is a member of the ATLAS Experiment.

The LHC is a program of the Geneva-based international scientific consortium known as the European Organization for Nuclear Research, or CERN. In March CERN announced that the LHC had successfully begun colliding protons at an energy three and a half times higher than previously achieved at any particle accelerator.

SMU’s new LOC serializer is what the industry calls an integrated circuit made for a specific use, or “ASIC” (application-specific integrated circuit). It was designed for the LHC’s high-radiation environment, as well as for high data bandwidth, low-power dissipation and extremely high reliability, says Ye.

SMU physicist Jingbo YeThe serializer was perfected over the past three years in the SMU Research Laboratory for Optoelectronics and ASIC Development in the Department of Physics. It can operate at cryogenic temperatures and has been tested down to liquid nitrogen temperatures of -346 degrees Fahrenheit. The serializer was designed to transmit data for the optical link readout system of the ATLAS Liquid Argon Calorimeter, an ATLAS sub-detector that measures the energies of electrons and photons generated at the center of ATLAS where protons collide. Because the electronic readout components are in the center of the ATLAS detector, they are essentially inaccessible for routine maintenance, so reliability is paramount, Ye says.

With a data transmission rate of 5.8 billion-bits per second, the SMU LOC serializer represents the first milestone for the SMU-led team. The team plans to develop an even faster ASIC serializer that transmits data at up to 10 billion-bits per second. Faster circuits are critical as CERN continues increasing the LHC’s luminosity, thereby generating more and more data.

SMU’s next goal is to increase both the data speed and the number of data lanes to produce an even faster LOC serializer, Ye says. “In the next few years, we hope to increase the total speed by a factor of 62 more than what is installed in ATLAS.”

Ye presented the SMU LOC serializer design in February at CERN. Made of complementary metal-oxide-semiconductor transistors in silicon-on-sapphire, the serializer’s design details also will be presented to scientists in April in Hamburg during the ATLAS Upgrade Week at the DESY laboratory, Germany’s premier research center for particle physics. The SMU LOC serializer research was funded by the National Science Foundation and the U.S. Department of Energy.

The new LOC serializer is critical for the upgrade of the Large Hadron Collider, called the Super LHC, which is planned to go online in 2017, Ye says.

“The original ATLAS design used a commercial serializer that was purchased from Agilent Technologies,” Ye said. “But for the Super LHC there is no commercial device that would meet the requirements, so – being typical physicists – we set out to design it ourselves.”

The ATLAS Liquid Argon Calorimeter’s existing optical link system, delivered by SMU physicists, has a data bandwidth of 2.4 terabits per second over 1,524 fibers, or 1.6 billion bits per second per fiber, more than 1,000 times faster than a T1 line of 1.544 megabits per second. The next generation of this optical link system will be based on the new SMU LOC serializer, and it will reach 152.4 terabits per second for the whole system.

“Fast information transfer from the detector to the computer processing system is a necessity for handling the significantly increasing amounts of data expected in the next round of LHC experiments,” says Ryszard Stroynowski, U.S. Coordinator for the ATLAS Liquid Argon Calorimeter, and chair and professor of physics at SMU. “It will allow ATLAS to be more selective in the choices of events sent for further analysis.”

A radiation-tolerant, high-speed and low-power LOC serializer is critical for optical link systems in particle physics experiments, Ye said, noting that specialized ASIC devices are now common components of most readout systems.

“The ever increasing complexity of particle physics experiments imposes new and challenging constraints on the electronics,” Ye says. “The LOC serializer was a formidable task, but our team was up to the challenge.”

Written by Margaret Allen

(Above, the LHC tunnel during its construction; SMU physicist Jingbo Ye in the lab.)

> Read more from the SMU Research blog

April 13, 2010|Research|

Research Spotlight: Top quark helps in hunt for Higgs boson

Standard Model fundamental particlesNew high-energy particle research by a team working with data from Fermi National Accelerator Laboratory further heightens the uncertainty about the exact nature of a key theoretical component of modern physics – the massive fundamental particle called the Higgs boson.

Analysis of data from particle collisions resulting in two leptons helps improve measurements of the mass of another heavy subatomic particle called the top quark, says SMU physicist Robert Kehoe, who led the team that calculated the measurement.

Improving the measurement of the mass of the top quark bears on the nature of the Higgs, says Kehoe, an assistant professor in SMU’s Department of Physics.

The Higgs was postulated in the 1960s to help explain how basic elements of the universe fit together and interact. It is responsible for a phenomenon called the Higgs mechanism, which gives mass to the fundamental particles of nature.

Physicists have searched for more than four decades to observe the never-before-seen Higgs. Now they hope it will be observed in the next few years since data started flowing recently from the world’s newest and largest high-energy particle accelerator, the CERN laboratory’s Large Hadron Collider near Geneva, Switzerland.

Researchers theorize that the top quark – because of its sizable mass – is sensitive to the Higgs and therefore may point to it. They theorize that knowing the mass of the top quark narrows the range of where the Higgs will be detected in CERN’s LHC collisions. The top quark is one of 16 species of subatomic particles that physicists have observed. It was predicted in the 1970s and observed in 1995. Increasingly precise measurements of its mass have been achieved almost every year since, and physicists closely watch the incremental measurements of the top quark.

The two-lepton analysis by Kehoe and SMU post-doctoral researcher Peter Renkel looked at data taken over four years during high-energy collisions at Fermilab, a Department of Energy proton-antiproton collider in Batavia, Illinois.

The two-lepton analysis is one of almost a dozen analyses of the mass of the top quark at a Fermilab experiment called “DZero.” The DZero experiment involves 500 physicists and is one of Fermilab’s two large experimental collaborations of scientists. The top quark mass was first observed simultaneously by these two experiments. Several measurements of the top quark’s mass from these two experiments are combined to a “world average” value.

The new world average is so precise that it constrains more tightly than ever the range of possible measurements for the mass of the Higgs, Kehoe says.

If the Higgs does prove different than currently expected, physicists may have to rework their long-standing theoretical framework, known as the Standard Model. Scientists worldwide are hoping to validate the Standard Model – which has worked well for more than 30 years to explain everything from radioactivity to computer chips – by actually observing the Higgs.

“The new results may be an indication that the Higgs boson has different properties than the Standard Model indicates,” Kehoe says. “It’s very difficult to devise a theory without some mechanism that mimics fairly well the Higgs mechanism. But if the underlying cause of this mechanism is significantly different, that will have a major impact on the fundamentals of the Standard Model. It could point to something deeper than the standard Higgs boson at work, and that is very interesting.”

(Above, a Fermilab graphic depicting the Standard Model fundamental particles.)

Read more at the SMU Research blog

December 8, 2009|Research|
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