A new gem inside the CMS detector

Sometimes big questions require big tools. That’s why a global community of scientists designed and built gigantic detectors to monitor the high-energy particle collisions generated by CERN’s Large Hadron Collider in Geneva, Switzerland. From these collisions, scientists can retrace the footsteps of the Big Bang and search for new properties of nature.

The CMS experiment is one such detector. In 2012, it co-discovered the elusive Higgs boson with its sister experiment, ATLAS. Now, CMS scientists want to push beyond the known laws of physics and search for new phenomena that could help answer fundamental questions about our universe. But to do this, the CMS detector needed an upgrade.

“Just like any other electronic device, over time parts of our detector wear down,” said Steve Nahn, a researcher in the U.S. Department of Energy’s Fermilab and the U.S. project manager for the CMS detector upgrades. “We’ve been planning and designing this upgrade since shortly after our experiment first started collecting data in 2010.”

The CMS detector is built like a giant onion. It contains layers of instruments that track the trajectory, energy and momentum of particles produced in the LHC’s collisions. The vast majority of the sensors in the massive detector are packed into its center, within what is called the pixel detector. The CMS pixel detector uses sensors like those inside digital cameras but with a lightning fast shutter speed: In three dimensions, they take 40 million pictures every second.

For the last several years, scientists and engineers at Fermilab and 21 U.S. universities have been assembling and testing a new pixel detector to replace the current one as part of the CMS upgrade, with funding provided by the Department of Energy Office of Science and National Science Foundation.

The pixel detector consists of three sections: the innermost barrel section and two end caps called the forward pixel detectors. The tiered and can-like structure gives scientists a near-complete sphere of coverage around the collision point. Because the three pixel detectors fit on the beam pipe like three bulky bracelets, engineers designed each component as two half-moons, which latch together to form a ring around the beam pipe during the insertion process.

Over time, scientists have increased the rate of particle collisions at the LHC. In 2016 alone, the LHC produced about as many collisions as it had in the three years of its first run. To be able to differentiate between dozens of simultaneous collisions, CMS needed a brand new pixel detector.

The upgrade packs even more sensors into the heart of the CMS detector. It’s as if CMS graduated from a 66-megapixel camera to a 124-megapixel camera.

Each of the two forward pixel detectors is a mosaic of 672 silicon sensors, robust electronics and bundles of cables and optical fibers that feed electricity and instructions in and carry raw data out, according to Marco Verzocchi, a Fermilab researcher on the CMS experiment.

The multipart, 6.5-meter-long pixel detector is as delicate as raw spaghetti. Installing the new components into a gap the size of a manhole required more than just finesse. It required months of planning and extreme coordination.

“We practiced this installation on mock-ups of our detector many times,” said Greg Derylo, an engineer at Fermilab. “By the time we got to the actual installation, we knew exactly how we needed to slide this new component into the heart of CMS.”

The most difficult part was maneuvering the delicate components around the pre-existing structures inside the CMS experiment.

“In total, the full three-part pixel detector consists of six separate segments, which fit together like a three-dimensional cylindrical puzzle around the beam pipe,” said Stephanie Timpone, a Fermilab engineer. “Inserting the pieces in the right positions and right order without touching any of the pre-existing supports and protections was a well-choreographed dance.”

For engineers like Timpone and Derylo, installing the pixel detector was the last step of a six-year process. But for the scientists working on the CMS experiment, it was just the beginning.

“Now we have to make it work,” said Stefanos Leontsinis, a postdoctoral researcher at the University of Colorado, Boulder. “We’ll spend the next several weeks testing the components and preparing for the LHC restart.”

View a photo gallery of the pixel detector installation in symmetry magazine.

How long have you worked at Fermilab?
It will be five years this summer. I started in 2012. Before that I had been working in private industry for about five years. It was a small company, about 30 or 40 people, and we were basically suppliers for places like Fermilab. Now I get to be the end user for these products, which is kind of nice.

What do you do as a lab mechanical engineer?
I work in the Technical Division Test and Instrumentation Department, mostly testing magnets. Right now, I’m working on the relocation of a test stand that was at the Central Helium Liquefier building. Now it’s going to HAB, the Heavy Assembly Building. We’re modifying the test stand to test the Mu2e transport solenoid production magnets.

What’s a typical day for you?
It varies day to day, depending on what state we’re in. Usually I’ll come into work, meet with technicians about modifications over at HAB, figure out the day’s work. Then I’ll work on design work, analysis or engineering notes. Later I’ll meet with the techs again to see if there are any issues or problems.

What do you like about working at Fermilab?
I like meeting people who come from all over the world, the variety of people. I also appreciate the overall concentration of intellect at Fermilab. It’s a unique opportunity to be working among so many different smart people and on so many different things outside my expertise.

You recently finished a term on the Engineering Advisory Committee. What was that like?
I was working with Paul Czarapata and Chris Mossey as part of the EAC. Various engineers got together to discuss different engineering-related issues with the director. I really liked that because it gave you an opportunity to look at engineering at the lab with a higher, 30,000-foot view. It was a good experience, because it takes you out of your bubble and lets you see how other people work and what kinds of issues they run into.

What do you do outside of work?
I play guitar in a band, the Blue Freedom Band. It’s a cover band that I play in with friends. We perform mostly in bars in the southwest suburbs or festivals. A lot of the people I play with grew up in that area, so they’ll book gigs different places around there.

Lately I’ve been taking improv classes in Chicago. It’s so much fun. My sister and I take classes together. We wanted something for us to be able to do together since we live far away from each other. We did some classes at Second City, and now we’re trying to do classes at iO.

Half a dozen local retirees gathered in the cold on a dreary weekday afternoon at Fermilab.

They were on the hunt for three invasive species: multiflora rose, buckthorn and honeysuckle. Carrying saws, hedge clippers and herbicides, the volunteers were ready to take on the invading plants. Chatting amiably with one another, they cut down invasive plants and carefully spritzed the roots with herbicide to prevent the plants from growing back.

Protective gear such as knee pads, thick gloves and safety glasses held thorns and branches at bay and prevented contact with the herbicides (which the volunteers are licensed to use by the state of Illinois).

After several hours, they departed, leaving behind a landscape where native species could once again flourish.

The volunteers who work with Fermilab ecologist Ryan Campbell to do this bushwhacking every winter are generally retirees who become involved because they find the work of preservation satisfying. For many of the volunteers, it becomes more than just a way to pass the time, and conservation becomes an active part of their life.

Penny Kasper, formerly a Fermilab physicist, is the president of Fermilab Natural Areas. Under her watch, the nonprofit organization helps conservation efforts across Fermilab’s 6,800 acres.

Kasper, like other volunteers, said she just got “sucked into it.” Some volunteers become so dedicated to the mission of removing invasive species that they carry hedge clippers with them in their car, just in case. Those pesky invasive species are a threat that requires dedicated action.

“If a habitat is not lost through development of some kind, the second greatest threat to habitat quality is invasive species,” Campbell said.

Invasive species are usually foreign or exotic species that are relatively new to the area. Because these plants and animals aren’t local, they don’t often have predators to hold them in check, and so they become out of control. For example, the brown tree snake has decimated the bird population of Guam because it has no natural predators there. This doesn’t happen in every case: Peaches are originally from China but aren’t invasive, even in Georgia, where they grow well.

“One thing that’s kind of a big misconception is that all non-native species are invasive, or all exotic plants are invasive,” Campbell said. “That’s not true. You can even have some native species that we would consider invasive depending on the situation.”

The main characteristic of invasive species is that they out-compete others in the area, like weeds in a garden. Multiflora rose, an invasive winding vine peppered with sharp thorns originally from east Asia, coils around itself like barbed wire and crowds out other plants. Removing it is made more difficult by the fact that it’s tough to distinguish from plants like black raspberry.

“There’s a lot of ways that organisms compete to survive,” Campbell said. “Invasive species can use a lot of different methods: They could be fast-growing and produce a lot of seeds like garlic mustard, or be like buckthorn, which can produce a chemical that inhibits the growth of other plants.”

Ecologists can measure the extent of an invasive plant’s spread by looking at the percent cover — a rough measure of how much of the area is taken up by the invasive species. Reducing cover from invasive species can be done through precision means, such as targeting individual plants, or the use of controlled fires.

Previously, before conservation efforts took root at Fermilab, invasive species could be found across the lab. Their presence could crowd out smaller plants, like wildflowers. But thanks to efforts from volunteers, visiting students and Fermilab’s Roads and Grounds Crew, the spread of invasive species has been pushed back.

Now, the native wildflowers bloom every year.

Twelve years after nine African-American students were escorted to Little Rock Central High School under the protection of the 101st Airborne Division and the aegis of Brown v. Board of Education, 22 young African-American men from Chicago flew to Oak Ridge, Tennessee.

Recruited from inner-city Chicago as a joint effort between the Atomic Energy Commission (AEC) and the U.S. Department of Labor, the men joined a special Training and Technology program to prepare them for jobs at the National Accelerator Laboratory. For four to six months, they were trained to become welders, machinists, electronics technicians, draftsmen or mechanical technicians. At the end of their training, they were flown back to Chicago, where jobs at the NAL — today known as Fermilab — were waiting for them.

From 1969 to 1974, the Training and Technology program provided training and skilled jobs to dozens of minority workers each year as part of the NAL effort to meet civil rights goals. Edwin Goldwasser, then deputy director of the laboratory, explained the stance in a 1969 article published in the Bulletin of Atomic Scientists:

Scientists are restless in these days of social strife. As a group, they tend to be concerned humanitarians. They believe in the intrinsically human value of basic research, yet they are repeatedly confronted by its military applications. At the same time, they find their science to be relatively dissociated from major social problems. … At the National Accelerator Laboratory, we have found it possible to pursue scientific objectives, and at the same time, to be more than mere spectators of the crises which grip our society.

On Fermilab’s 50th anniversary, we take a look back at its connections to the civil rights movement using archives and original interviews.

Site origins and fair housing

Fermilab today can trace its origins back to a contentious, multimillion dollar accelerator project known in the mid ‘60s as the 200 GeV project.

Initial proposals to host the project came from hundreds of locations across the country — it was in extremely high demand. Eventually, the list of potential sites was whittled down to a few finalists, including existing national labs in New York and California, as well as the small town of Weston, Illinois.

It was almost not to be. In 1966, after Weston was selected as a finalist, pressure mounted against it: Illinois was the only one of the finalist states that lacked fair housing legislation to protect minorities. But the other advantages that Weston provided, such as proximity to urban centers and low construction costs, superseded the AEC’s concerns about civil rights. In December 1966, Weston was chosen to be the location for the 200 GeV project, pending funding approval. Only days later, the Illinois state legislature voted against fair housing legislation.

Tensions continued to mount as the 200 GeV project faced funding authorization hearings. NAACP representative Clarence Mitchell spoke at the hearings, saying that the choice of Weston was an “example of how human dignity and fair play get short shrift from some top government agencies.”

Senator Joseph Pastore, chairman of the Joint Committee on Atomic Energy, spoke out against appropriation of funds to the project, saying “In the name of advancing science and technology, we should not be guilty of retreating from our boasted principles of equity, equality and humility.”

These arguments played out on the political backdrop of the time. Civil rights and antiwar protests ionized the 200 GeV project and turned it into a lightning rod for criticism. Additionally, prominent physics communities at Berkeley and Brookhaven laboratories both balked at sending the frontiers of high-energy physics to what they felt was a desolate Midwest full of cornfields and little else.

In June 1967, the NAACP organized a protest that would march from nearby Warrenville to the Weston Village. In an effort to ease tensions Robert Wilson, director of the newly established National Accelerator Laboratory, sent Martin Luther King Jr. a telegram, writing that the scientists “strongly support the struggle for open housing in Illinois. Science has always progressed only through the free contribution of people of all races and creeds.” It is not known if King, who stopped by briefly, ever responded, but the protest proceeded peacefully.

However, in July, Weston managed to secure the funding for the 200 GeV project over the protestations of its critics.

As Wilson and Goldwasser planned the growing laboratory, issues of race and inequality were central to their thinking, and they spent a significant portion of their time discussing affirmative action. Among the first actions they took was the creation of a human rights policy that laid out the axiom: “It will be the policy of the National Accelerator Laboratory to seek the achievement of its scientific goals within a framework of equal employment opportunity and of a deep dedication to the fundamental tenets of human rights and dignity.”

In light of these efforts, Mitchell, who had previously been against NAL, changed his stance to one of support and wrote favorably in support of the lab when it later struggled to get funding.

By the end of the year, fair housing became the law of the land with the passage of the Civil Rights Act of 1968. It was supported by Senate Minority Leader Everett Dirksen (R-IL), who many suspected treated the bill more favorably because of the choice of Illinois for the 200 GeV project.

Initiatives and affirmative action

One of the crucial early hires Goldwasser and Wilson made for the young laboratory was that of Kennard Williams. As the NAL equal opportunity and community relations officer, Williams was instrumental in organizing minority outreach initiatives, such as hiring minority contractors to do construction work.

In 1969, about 40 percent of small contracts (those below $10,000) for the Fermilab Village were awarded to African-American contractors. These rates were unusual for the time period, during which less than 1 percent of all government funding for contracts went to minorities, including women.

Williams was also involved with outreach and training programs, including NAL’s Technology and Training (TAT) program. In order to increase diversity at NAL and offer opportunities to minorities — particularly African-Americans —  TAT facilitated the recruitment and training of dozens of local minorities every year it ran. NAL trainees were flown to Oak Ridge National Laboratory and instructed in the skills they would need for their jobs back in Illinois.

Although it ended after only five years, TAT served as a model for future minority training programs at the lab.

The first set of TAT trainees, a group of African-American men from inner-city Chicago, stayed in military dormitories that were relics from World War II during their months at Oak Ridge. They lived and studied there together, and were instructed in math, science and technical skills for their assigned vocation.

At that time, all of the instructors were white, according to Halbert Landers, a member of the first TAT program, and a longtime lab employee.

“That was a sad thing,” he said. “But [it] didn’t cause a problem because all of our instructors went far and beyond the call of duty.”

Although the TAT program was comprehensive and rigorous, it did not teach trainees everything, according to Landers.

“The one area that I wish I would’ve learned down at the TAT program was how to read a slide rule,” he said. “When I came back from the TAT program there weren’t really any computers — we had to do all the mathematics by hand, or as a lot of the engineers did, use a slide rule.”

During the months that the trainees spent in Oak Ridge, they also grew close and became friends.

“We kinda made a pact between us that when we got on the plane, that whatever differences we had … we weren’t gonna bring them down there to Oak Ridge,” Landers said. “Even when we came back to Fermilab, we were one, as it were.”

Fermilab technical supervisor Curtis Danner, who was recruited to NAL out of a vocational school in 1970, recalled that this camaraderie transferred to other African-American members of Fermilab, who frequently supported one another and “treated each other as family.”

The lab, too, gave institutional backing to many of its employees. Early on, Landers had difficulty finding housing in the area around the lab and was told that there were no vacancies. Landers checked with the lab’s personnel department, who sent a white employee to inquire about housing availability in the same location. That employee told that housing was, in fact, available. After pressure from the lab, Landers was able to get an apartment.

Inclusive views were not shared by all members of the lab, which Landers discovered only when he was invited to dinner by his supervisor. Over the course of the meal, Landers’ supervisor revealed that he campaigned for George Wallace and “didn’t feel that black people needed to have a leader speaking for them because white folks didn’t.”

“I felt that they took their personalities out and put them in the glove compartment of their car when they went to work, and then when they left Fermilab and got back in their car, they put their personalities back in.” Landers said. “But as I say, when it came to work, I never felt that.”

The TAT program gave minorities a foot into the door at the lab, but it was not the same as a full education. When the lab began hiring staff with associates and bachelor’s degrees, most of whom were white men, TAT graduates like Landers had trouble advancing.

“They brought them in, had higher pay, better responsibilities and also would try to put them in charge of the minorities,” he said.

Still, many African-American employees and TAT alumni such as Landers and Danner persisted and were eventually recognized as valuable members of the Fermilab community.

“As a whole we were all treated fairly,” Danner said. “Everything was not perfect because we don’t live in a perfect world, but I had no real complaints, and I’m still here after all those years.”

In 1981, on the 12th anniversary of the TAT program, trainees of the first TAT program issued the following statement.

In Appreciation,

We the trainees from the first training program (TAT, begun Feb. 9, 1969) would like to take this time to express our thanks to those who helped to make it possible for our group to become productive and worthwhile citizens.

Having come out of an environment that was not scientific or technically oriented, we have found that given the opportunity and guidance to achieve it can be done. We have found that prejudice is not environmental but rather an individual thing and need not exist where people truly have an understanding of themselves in relation to their environment. We have learned, in more ways than one, what it means to be a worthwhile and productive citizen within the framework of our jobs and our communities.

***Editor’s note: Readers interested in learning more about Fermilab’s history as it pertains to civil rights should look to pages 79–89 and pages 104–108 of the book Fermilab: Physics, the Frontier, and Megascience.

On Sunday, March 12, Fermilab hosted “Pregúntale a un Científico,” which was attended by almost 100 curious neighbors of all ages.

The Spanish-language offering was part of the laboratory’s long-standing Ask-a-Scientist program. Although the program has been around in its current form for 15 years, this is the first time an event has been held in a language other than English.

Over the course of three hours, the attendees heard a lecture about neutrinos and Fermilab’s role in studying them by Minerba Betancourt, a Fermilab postdoctoral researcher. They were also given a tour of different areas of Fermilab, including the Main Control Room, Ramsey Auditorium and the linear accelerator corridor.

Ask-a-Scientist is held on the first Sunday of every month and features a lecture, tour of the facilities and opportunity to ask Fermilab physicists any physics question you want.

Edgar Valencia, a postdoctoral researcher from The College of William and Mary working on the MINERvA experiment who led one of the tours, said that the tour helped dispel myths that Fermilab was a closed-off and secretive place.

“Events like these are important to show the community that all we’re really doing is science,” he said.

“There was interest in doing it in Spanish, so we got people together and set it up,” said Peter Garbincius, who founded and heads the Ask-A-Scientist program. “We had no idea what to expect though.”

Much of the event is the same as its English-language counterpart, but there are still a few tricky phrasings to work out.

“Some things are hard to translate to Spanish,” Valencia said.

His advice? Avoid technical English and use common words if you can. Talking about muons or electrons? Try “las partículas cargadas,” which literally translates as “charged particles.”

Daniel Laguna, a visiting high school student, said that what he found most interesting was the collaboration between physicists.

“I didn’t know about the worldwide collaboration, with people from Fermilab working with CERN and stuff, to solve these problems,” he said.

Valencia said that when people come here and take part in the tour, they want to know more.

“I was only expecting 10 or 20 people, so I was really surprised at the numbers and the receptiveness,” he said. “I told them to come back and visit the Lederman Science Center.”

According to Garbincius, the event was so successful that Fermilab is considering scheduling Pregúntale a un Cientifíco on a regular basis.

It’s an exciting time for the Deep Underground Neutrino Experiment. With the worldwide scientific collaboration nearing 1,000 scientists from 30 countries, prototype detectors being built and tested at CERN, and construction scheduled to begin this year at the Sanford Underground Research Facility, the future looks bright for this most ambitious of long-distance neutrino experiments.

In a vote earlier this month, the DUNE collaboration elected a new co-spokesperson to see them through the next two years. And from a pool of highly qualified candidates they chose someone who has been with the experiment since its very beginnings: Edward Blucher, professor of physics and former chair of the Physics Department at the University of Chicago. Blucher also serves as the head of the Fermilab Physics Advisory Committee, a job he will step down from when he assumes his new role with DUNE.

In the late 2000s, Blucher chaired the executive board that led to the Long-Baseline Neutrino Experiment, one of the precursors of DUNE. He’s dedicated most of his career to one of DUNE’s science goals — shedding light on the matter-antimatter asymmetry of the universe — and is excited by the scale of this experiment and its potential for a breakthrough.

“Years ago we could not have imagined the alignment we have now between the collaboration, the laboratories and the funding agency,” he said. “It’s been in discussions for a long, long time, and we were hopeful, but it wasn’t real. Now I think we’ve crossed that bridge. It’s a real thing now, and it’s incredibly exciting, but also extremely challenging for the collaboration.”

The challenges, he said, are not just technical. With the prototype detectors under way and the short-baseline neutrino program at Fermilab providing important research and development for liquid-argon neutrino detector technology, an important part of the next few years will be for the collaboration to draw effectively on all of the talent available worldwide, Blucher said.

“How do we engage the enormous pool of talent in the collaboration to build the best possible experiment?” he said. “For DUNE to be successful, it is essential that we find ways to involve and engage all of our collaborators.”

Blucher will take over the position from André Rubbia of ETH Zurich and will join Mark Thomson of the University of Cambridge as co-spokesperson.

“I have known Ed for a number of years, and I am looking forward to working closely with him,” Thomson said. “The next two years are incredibly important for DUNE, and I’m pleased to have someone of Ed’s caliber in this role.”