Patty McBride is next CMS deputy co-spokesperson

The CMS experiment, which studies particle collisions at the Large Hadron Collider at CERN in Switzerland, is heading into a new era of research under the guidance of Fermilab scientist Patty McBride, one of two incoming deputy spokespersons.

She begins her two-year term on Sept. 1, serving in the role with Luca Malgeri of CERN. She will serve as deputy to incoming CMS spokesperson Roberto Carlin, INFN researcher and professor at the University of Padua, who concludes his term as deputy spokesperson.

McBride says that her love for physics began in eighth grade, when her mom gave her a book on particle accelerators, sparking her interest in investigating the subatomic world. After studying physics in college at Carnegie Mellon, she received her doctorate at Yale University and a postdoc at Harvard University. She started at Fermilab in 1994 and worked on a number of experiments and in various leadership positions. In 2005, she joined the CMS collaboration, working as head of the CMS Center at Fermilab from 2012 to 2013 and, later, as U.S. CMS operations program manager. In 2014, she became head of the Fermilab Particle Physics Division, where she served for four years.

“Patty is ideally suited to be one of the leaders of the international CMS collaboration since she brings deep experience in many aspects of particle physics,” said Joel Butler, Fermilab scientist and outgoing CMS spokesperson. “She possesses excellent judgement and problem-solving skills and the ability to inspire people to work together toward common goals.”

The giant CMS detector records particle collisions at the Large Hadron Collider to help scientists better understand the smallest constituents of our universe. In 2012, CMS co-discovered, along with the LHC’s ATLAS experiment, the long-sought-after Higgs boson, which led to a Nobel Prize in 2013 for the theorists who proposed it. The 4,000-strong CMS collaboration is now taking precise measurements of properties of the Higgs boson and searching for new physics, such as particles that could make up dark matter.

As deputy co-spokesperson, McBride will push to publish new physics results from the most recent LHC run and to prepare the experiment for the next run. She will also help direct the project to upgrade the detector to handle the higher-intensity collisions that will emerge from a revamped LHC, to come online in 2026. The new and improved High-Luminosity LHC, as it is called, will crank up the number of particle collisions to five to seven times its current rate and generate 30 times the data CMS has collected so far.

“CMS’s upgrades will prepare the detector and its instruments for the avalanche of data from the collisions once the LHC is upgraded,” McBride said.

McBride says she’s excited to help lead CMS into the next phase of its life and to work with an international collaboration from over 40 countries.

“I’m looking forward to working with such a large group of scientists from all over the world who will push CMS to improve,” McBride said. “It’s a privilege to be a part of a group that made such an important discovery in 2012, and it will be a privilege to help lead them to further discoveries.”

On Oct. 1, Fermilab and University of Chicago scientist Rich Kron begins his three-year term as director of the Dark Energy Survey, or DES, hosted by Fermilab. Fellow Fermilab scientist Tom Diehl will serve as deputy director.

From 2003-2008, Kron was director of the Sloan Digital Sky Survey, an astronomical survey in which Fermilab was heavily engaged until 2008. In 2010, he stepped into the role of DES deputy director. Now, as incoming director, he succeeds Fermilab and University of Chicago scientist Josh Frieman, who became head of the Fermilab Particle Physics Division earlier this year.

The Dark Energy Survey is a multinational, collaborative effort to map hundreds of millions of galaxies and stars to better understand dark energy, the phenomenon behind the increasingly rapid expansion of the universe. Using a powerful camera installed on a telescope on a Chilean mountaintop, DES researchers are creating detailed maps of the southern sky to uncover patterns in the distribution of celestial objects that reflect — or reveal — the impact of dark energy on the formation of structure in the universe. They are also discovering and measuring properties of several thousand supernovae —distant exploding stars — to chart dark energy’s influence on the history of cosmic expansion. The data will help researchers narrow in on dark energy’s nature.

As the new DES director, Kron will lead the 400-strong collaboration through its final data-taking season, which runs from September 2018 to January 2019.

“I’m honored to be given the opportunity to lead the Dark Energy Survey to the conclusion of its operations and the production of the final science results,” Kron said. “My predecessor Josh Frieman capably led the collaboration through the past eight years, and I have learned a lot from him.”

Each season of observation — a total of six for DES — adds more and more data, increasing the survey’s sensitivity to distant galaxies. In 2019, the collaboration will have amassed its full data collection.

“We’ll have the entire data collection packaged together and can write the final scientific papers. We’ll make sure everyone is engaged and gets the opportunity to take advantage of this huge effort,” Kron said.

“Rich is an internationally recognized astronomer who brings a wealth of experience and expertise to this role,” Frieman said. “He has done an excellent job as DES deputy director and will be a strong leader for DES as it heads into its last months of data taking and its golden years of science analysis.”

And Tom Diehl, incoming DES deputy director, has been with the collaboration since its early years. He worked on the construction of the camera used for DES and has also served as DES operations scientist since 2012.

“It’s an honor for Rich to ask me to be deputy director. It will be my pleasure to do my best to help the collaboration and Rich,” Diehl said. “We have a lot of exciting work to do.”

Both look forward to “getting the science out,” Kron said, sharing the findings of the forefront experiment they’ve helped advance for several years.

“DES is on a good track thanks to the efforts of many other colleagues at Fermilab and elsewhere, and I look forward to working with this great team,” Kron said.

Editor’s note: The following news release about the discovery of a long-sought decay of the Higgs boson is being issued by the U.S. Department of Energy’s Fermi National Accelerator Laboratory on behalf of the U.S. scientists working on the LHC. Fermilab serves as the U.S. hub for the CMS experiment at the LHC and the roughly 1,000 U.S. scientists who work on that experiment, including about 100 Fermilab employees. Fermilab is a Tier 1 computing center for LHC data and hosts a Remote Operations Center to process and analyze that data. Read more information about Fermilab’s role in the CMS experiment and the LHC. 

Today at CERN, the Large Hadron Collider collaborations ATLAS and CMS jointly announced the discovery of the Higgs boson transforming into bottom quarks as it decays. This is predicted to be the most common way for Higgs bosons to decay yet was a difficult signal to isolate because background processes closely mimic the subtle signal. This new discovery is a big step forward in the quest to understand how the Higgs enables fundamental particles to acquire mass.

After several years of refining their techniques and gradually incorporating more data, both experiments finally saw evidence of the Higgs decaying to bottom quarks that exceeds the 5-sigma threshold of statistical significance typically required to claim a discovery. Both teams found their results were consistent with predictions based on the Standard Model.

“The Higgs boson is an integral component of our universe and theorized to give all fundamental particles their mass,” said Patty McBride, distinguished scientist at the U.S. Department of Energy’s Fermi National Accelerator Laboratory and recently elected as one of the deputy spokespeople of the CMS experiment. “But we haven’t yet confirmed exactly how this field interacts — or even if it interacts — with all the particles we know about, or if it interacts with dark matter particles which remain to be detected.”

Higgs bosons are produced in only roughly one out of a billion LHC collisions and live only a tiny fraction of a second before their energy is converted into a cascade of other particles. Because it’s impossible to see Higgs bosons directly, scientists use these secondary particle decay products to study the Higgs’s properties. Since its discovery in 2012, scientists have been able to identify only about 30 percent of all the predicted Higgs boson decays. According to Viviana Cavaliere, a physicist at DOE’s Brookhaven National Laboratory who works on the ATLAS experiment, finding the Higgs boson decaying into bottom quarks has been priority number one for the last several years because of its large decay rate.

“Theory predicts that 60 percent of Higgs bosons decay into bottom quarks,” said Cavaliere, who is also using this process to search for new physics. “Finding and understanding this channel is critical because it opens up the possibility for us to examine the behavior of the Higgs, such as whether it could interact with new, undiscovered particles.”

The Higgs field is theorized to interact with all massive particles in the Standard Model, the best theory scientists have to explain the behavior of subatomic particles. But many scientists suspect that the Higgs could also interact with massive particles outside the Standard Model, such as dark matter. By finding and mapping the Higgs bosons’ interactions with known particles, scientists can simultaneously probe for new phenomena.

“A fraction of Higgs bosons could be producing dark matter particles as part of their decay,” said Giacinto Piacquadio, a physicist at Stony Brook University who co-led the Higgs-to-bottom-quarks analysis group. “Because the decay of the Higgs boson to bottom quarks is so common, we can use it to put constraints on potentially invisible decays as well as use it to probe for new physics directly.”

Even though this decay is the most popular path, spotting it in the experimental data was no walk in the park. Every proton-proton collision at the LHC produces a splattering of subatomic byproducts, one of the most common being bottom quarks. These bottom quarks then quickly decay into other kinds of particles, leaving behind vast showers of particles in the detectors. Tracing these particle showers back to two bottom quarks (and then figuring out which ones came from a Higgs boson) is extremely delicate and labyrinthine work.

“Being able to identify and isolate bottom quarks in the experimental data is a huge challenge and required precise detector calibration and sophisticated b-quark tagging,” Piacquadio said. “We were only able to do these analyses thanks to years of work that came before.”

To spot this process, the ATLAS and CMS collaborations each combined data from the first and second runs of the LHC and then applied complex analysis methods to the data.

“Finding just one event that looks like two bottom quarks originating from a Higgs boson is not enough,” said Chris Palmer, a scientist at Princeton who worked on the CMS analysis. “We needed to analyze hundreds of thousands of events before we could illuminate this process, which is happening on top of a mountain of similar-looking background events.”

According to Palmer, these deceptive background events made the analyses almost impossible to perform based on isolated bottom quarks alone.

“Luckily, there are a few Higgs production mechanisms that produce identifiable particles as byproducts,” Palmer said. “We used these particles to tag potential Higgs events and separate them out from everything else. So we really got a two-for-one deal with this analysis because not only did we find the Higgs decaying to bottom quarks, but we also learned a lot about its production mechanisms.”

The next step is to increase the precision of these measurements so that scientists can study this decay mode with a much greater resolution and explore what secrets the Higgs boson might be hiding.

More than 1,700 scientists, engineers and graduate students from the United States collaborate on the experiments at the LHC, most of them on the CMS and ATLAS experiments, through funding by the Department of Energy Office of Science and the National Science Foundation. Brookhaven National Laboratory serves as the lead national laboratory for participation in the ATLAS experiment, and Fermi National Accelerator Laboratory serves as the lead national laboratory for participation in the CMS experiment.

CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. It has its headquarters in Geneva. At present, its member states are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Israel, Italy, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Cyprus, Slovenia and Serbia are associate members in the pre-stage to membership. India, Lithuania, Ukraine, Turkey and Pakistan are associate members. Japan, the Russian Federation, the United States of America, the European Union, JINR and UNESCO have observer status.

Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance LLC. Visit Fermilab’s website at www.fnal.gov and follow us on Twitter at @Fermilab.

The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2018, its budget is $7.8 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives more than 50,000 competitive proposals for funding and makes about 12,000 new funding awards.

 

On Aug. 21, a beam of electrons successfully circulated for the first time through a new particle accelerator at the Department of Energy’s Fermilab.

The milestone marks the beginning of a research program that positions the particle storage ring, called the Integrable Optics Test Accelerator, as a standout among the world’s accelerators — an innovative test bed dedicated to the science of particle acceleration. A high-precision machine with a flexible configuration, it will allow researchers to test theories, make discoveries and create inventions that push past the limits of existing machines.

“We’ve built a modern, next-generation accelerator for beam physics research that will have impacts in multiple areas of science,” said Vladimir Shiltsev, head of the Fermilab Accelerator Physics Center. “It opens opportunities for a new era of accelerators.”

The centerpiece of the Fermilab Accelerator Science and Technology facility, IOTA will send electrons and protons around its 40-meter circumference, giving scientists the latitude to explore new ways of manipulating particle beams that will pay dividends in other fields.

When Fermilab scientists began planning IOTA, about 10 years ago, they set out to design a machine for the deep exploration of techniques that could advance the numerous scientific fields that depend on accelerators. They came up with an elegant, compact ring for testing the concepts that they judged to be the most important.

“IOTA is one of a kind — a particle storage ring designed and built specifically to host novel experiments with both electrons and protons and develop innovative concepts in accelerator science,” said Fermilab physicist Alexander Valishev, head of the team that developed and constructed IOTA.

Fermilab has formed partnerships with others interested in advancing accelerator science and technology at FAST. The facility has already attracted 29 institutional partners, including European institutions, U.S. universities, national laboratories and members of industry.

“We’re seeking engagement from a wider community of scientists,” Valishev said.

The achievement of first beam is the pinnacle of many years of that intense, collaborative work.

“An eager and highly motivated group of particle beam physicists from universities and laboratories around the world have been awaiting the completion of IOTA for fundamental research,” said Northern Illinois University President’s Research Professor and Director of Accelerator Research Swapan Chattopadhyay, Fermilab distinguished scientist. “We congratulate the IOTA team for having reached this significant milestone.”

The beam’s the thing

Usually, the accelerators that make headlines — such as CERN’s Large Hadron Collider in Europe — operate in service to studies of the basic properties of subatomic particles. By accelerating particle beams to close to light speeds and smashing them apart, these machines expose nature’s fundamental constituents in the ensuing debris, allowing scientists to study them.

IOTA is different. The 40-meter-circumference ring will accelerate beams to investigate — not particles emerging from collisions — but rather the beams themselves. It’s one of only a handful of accelerators in the world for beam physics studies.

But even among this small group, IOTA is different. It’s also the only research accelerator that will be able to switch between beams of electrons and protons. (IOTA’s first proton beams are expected in 2019.)

And whereas many other research accelerators are linear, meaning that the beam travels down a straight path, IOTA is a circular accelerator dedicated to beam studies. This means it can send beam around its 40-meter path thousands to millions of times. With each pass, various beam effects are amplified, enabling scientists to better understand how they arise in the first place. It’s a way to mimic the processes limiting the operation of much larger and higher-energy machines, from Fermilab proton accelerators to the LHC and future supercolliders.

“This facility offers a flexibility that can be useful to a wider community — above and beyond the needs of high-energy physics,” Valishev said.

It’s an opportunity that’s unavailable at particle accelerators that provide beam dedicated to particle physics experiments, with operators who can’t afford to dedicate time to often disruptive beam experimentation.

“Running beam physics studies in an operational particle physics machine is a tremendous challenge. You can’t really mess with the background environment, the beam losses,” said Shiltsev, referring to undesirable beam effects. “But accelerator physicists want to mess with the beam losses, to study them in detail and explore ways to suppress them. We want to push those effects to their maximum.”

And they can take the knowledge they gain from that boundary-pushing to the drawing board to improve the design of future particle physics machines — and accelerators for everyday life.

Over 30,000 particle accelerators are in operation in the world. Most are used in industry and for broad applications, such as for the environment or medicine (accelerators for cancer research use X-rays generated with a small electron accelerator in a hospital or produce medical isotopes for imaging).

What’s in a beam?

IOTA’s rich research program spans the gamut from shaping beams packed with hundreds of millions or billions of electrons or protons to examining beams made of only a single particle. Scientists will use IOTA to explore multiple beam acceleration technologies, including several that have been proposed but never realized.

“With IOTA, scientists from around the world will be able to use the next-generation accelerator to collaborate and test innovative ideas, finding ways to reach the next level of accelerator beam power,” said Fermilab Head for Accelerator Science Programs Sergei Nagaitsev, one of the researchers who proposed the IOTA concept.

One area that could dramatically change the world of accelerators is the capability for generating ultrahigh-intensity beams.

Roughly translated, “intensity” is the number of particles that form a beam. The more particles a beam can carry, the more that can be smashed together at a time, and the more you can speed up the timeline for discovery. High intensity is a high priority for the field of particle physics.

But unchecked, an increasingly intense beam becomes increasingly unstable and can produce unwanted effects, including beam loss phenomena, in which particles depart from the pack. That limits the beam’s performance, making it far less useful for discovery.

“We want to push the physics to do more, so we have to push the beam to lose less,” Shiltsev said. “Having this ring gives us the chance to really understand how to attack this problem.”

Accelerator scientists have proposed various methods to tame or compensate for beams’ unruly behavior. With IOTA, scientists have a high-tech platform to fully explore these techniques, including several that could not be tested previously. One of them uses low-energy electrons as a kind of focusing lens. Another uses instruments collectively known as integrable optics — the “IO” in IOTA.

“These are new techniques for beam control,” Shiltsev said. “Nobody’s done this before.”

But “IO” is only the beginning.

With IOTA, accelerator scientists will also capitalize on Fermilab’s existing strengths in beam acceleration. Beam cooling, for example, is a method for creating tighter, more orderly beams, making them easier to manipulate and accelerate. Fermilab has a strong history in its development. Between 2005 and 2011, it operated the highest-energy electron cooler in the world.

The focus of the current beam cooling effort has a fancy name: optical stochastic cooling. Building on the lab’s current expertise, IOTA scientists will take the technology to the next level.

“If the technology is successful, it could pave the way for electron-ion colliders in an energy range that isn’t currently accessible,” Valishev said.

IOTA invites research in other tantalizing topics. For example, scientists can use the test accelerator to dive deep into little understood quantum phenomena, such as the physics of beams made of a single electron. Scientists could learn whether their behavior is “textbook or has some additional strangeness,” Shiltsev said.

“We can get to the essence of the deep quantum physics of these objects. So there are other nice things we can do using IOTA — unique experiments in fundamental physics,” Shiltsev said.

“While IOTA promises to open up new vistas to reach higher-intensity charged particle beams in the future, more fundamentally it will allow, for the first time in history, classical feedback control of a single electron,” Chattopadhyay said. “We want to understand how its quantum nature blurs this point-like fundamental particle in space.”

IOTA outlook

With first beam comes both the satisfaction of accomplishment and the prospect of doing impactful science.

“Seeing first beam in a research accelerator is a rare experience in the life of a scientist, or an accelerator physicist, when you know you’ve accomplished something big — even though it’s just first beam,” Valishev said. “I’m proud for our team.”

Over the next year, the Fermilab team will install the device that will supply protons to IOTA, the proton injector. Once it is in place, it will complete the trio of particle accelerators that make up the FAST facility: the proton injector, the electron injector (completed in 2017) and the IOTA ring.

“IOTA is unique, and what’s ahead is years of exciting, very interesting research,” Shiltsev said. ” We look eagerly forward to it.”

Learn more about IOTA at the FAST website and in the Journal of Instrumentation. You can see presentations at two recent IOTA workshops in 2015 and 2018.

The IOTA program is supported by the DOE Office of Science.