Next-generation camera for the South Pole Telescope takes data on early universe

Chicago-area scientists lead effort to probe the cosmic microwave background

Deep in Antarctica, at the southernmost point on our planet, sits a 33-foot telescope designed for a single purpose: to make images of the oldest light in the universe.

This light, known as the cosmic microwave background, or CMB, has journeyed across the cosmos for 14 billion years — from the moments immediately after the Big Bang until now. Because it is brightest in the microwave part of the spectrum, the CMB is impossible to see with our eyes and requires specialized telescopes.

The South Pole Telescope, specially designed to measure the CMB, has recently opened its third-generation camera for a multiyear survey to observe the earliest instants of the universe. Since 2007, the SPT has shed light on the physics of black holes, discovered a galaxy cluster that is making stars at the highest rate ever seen, redefined our picture of when the first stars formed In the universe, provided new insights into dark energy and homed in on the masses of neutrinos. This latest upgrade improves its sensitivity by nearly an order of magnitude — making it among the most sensitive CMB instruments ever built.

“Being able to detect and analyze the CMB, especially with this level of detail, is like having a time machine to go back to the first moments of our universe,” said University of Chicago Professor John Carlstrom, the principal investigator for the South Pole Telescope project.

“Encoded in images of the CMB light that we capture is the history of what that light has encountered in its 14 billion-year journey across the cosmos,” he added. “From these images, we can tell what the universe is made up of, how the universe looked when it was extremely young and how the universe has evolved.”

Located at the National Science Foundation’s Amundsen-Scott South Pole Station, the South Pole Telescope is funded and maintained by the National Science Foundation in its role as manager of the U.S. Antarctic Program, the national program of research on the southernmost continent.

“The ability to operate a 10-meter telescope, literally at the end of the Earth, is a testament to the scientific capabilities of the researchers that NSF supports and the sophisticated logistical support that NSF and its partners are able to provide in one of the harshest environments on Earth,” said Vladimir Papitashvili, Antarctic astrophysics and geospace sciences program director in NSF’s Office of Polar Programs. “This new camera will extend the abilities of an already impressive instrument.”

The telescope is operated by a collaboration of more than 80 scientists and engineers from a group of universities and U.S. Department of Energy national laboratories, including three institutions in the Chicago area. These research organizations — the University of Chicago, Argonne National Laboratory and Fermi National Accelerator Laboratory — have worked together to build a new, ultrasensitive camera for the telescope, containing 16,000 specially manufactured detectors.

“Built with cutting-edge detector technology, this new camera will significantly advance the search for the signature of early cosmic inflation in the cosmic microwave background and allow us to make inroads into other fundamental mysteries of the universe, including the masses of neutrinos and the nature of dark energy,” said Kathy Turner of DOE’s Office of Science.

“Baby pictures” of the cosmos

The CMB is the oldest light in our universe, produced in the intensely hot aftermath of the Big Bang before even the formation of atoms. These primordial particles of light, which have remained nearly untouched for nearly 14 billion years, provide unique clues about how the universe looked at the beginning of time and how it has changed since.

“This relic light is still incredibly bright — literally outshining all the stars that have ever existed in the history of the universe by over an order of magnitude in energy,” said University of Chicago professor and Fermilab scientist Bradford Benson, who headed the effort to build this new camera.

However, because most of the energy is in the microwave part of the spectrum, to observe it we need to use special detectors at observatories in high and dry locations. The South Pole Station is better than anyplace else on Earth for this: It is located atop a two-mile-thick ice sheet, and the extremely low temperatures in Antarctica mean there is almost no atmospheric water vapor.

Scientists are hoping to plumb this data for information on a number of physical processes and even new particles.

“The cosmic microwave background is a remarkably rich source for science,” Benson said. “The third-generation camera survey can give us clues on everything from dark energy to the physics of the Big Bang to locating the most massive clusters of galaxies in the universe.”

The details of this “baby picture” of the cosmos will allow scientists to better understand the different kinds of matter and energy that make up our universe, such as neutrinos and dark energy. They may even find evidence of the gravitational waves from the beginning of the universe, regarded by many as the “smoking gun” for the theory of inflation. It also serves as a rich astronomical survey; one of the things they’ll be looking for are some of the first massive galaxies in the universe. These massive galaxies are increasingly of interest to astronomers as “star farms,” forming the first stars in the universe, and since they are nearly invisible to typical optical telescopes, the South Pole Telescope is perhaps the most efficient way to find them.

“Nothing that comes out of a box”

The South Pole Telescope collaboration has operated the telescope since its construction in 2007. Grants from multiple sources — the National Science Foundation, the U.S. Department of Energy, and the Kavli and Moore foundations — supported a second-generation polarization-sensitive camera. The latest third-generation focal plane contains 10 times as many detectors as the previous experiment, requiring new ideas and solutions in materials and nanoscience.

“From a technology perspective, there is virtually nothing that comes ‘out of a box,’” said Clarence Chang, an assistant professor at the University of Chicago and physicist at Argonne involved with the experiment.

For the South Pole Telescope, scientists needed equipment far more sensitive than anything made commercially. They had to develop their own detectors, which use special materials for sensing tiny changes in temperature when they absorb light. These custom detectors were developed and manufactured from scratch in ultraclean rooms at Argonne.

The detectors went to Fermilab to be assembled into modules, which included small lenses for each pixel made at the University of Illinois at Urbana-Champaign. After being tested at multiple collaborating universities around the country, the detectors made their way back to Fermilab to be integrated into the South Pole Telescope camera cryostat, designed by Benson. The camera looks like an 8-foot-tall, 2,500-pound optical camera with a telephoto lens on the front, but with the added complication that the lenses need to be cooled to just a few degrees above absolute zero. (Even the Antarctic isn’t that cold, so it needs this special cryostat to cool it down further.)

Finally, the new camera was ready for its 10,000-mile journey to Antarctica by way of land, air and sea. On the final leg, from NSF’s McMurdo Station to the South Pole, it flew aboard a specialized LC130 cargo plane outfitted with skis so that it could land on snow near the telescope site, since the station sits atop an ice sheet.  The components were carefully unloaded, and a team of more than 30 scientists raced to reassemble the camera during the brief three-month Antarctic summer — since the South Pole is not accessible by plane for most of the year due to temperatures that can drop to minus 100 degrees Fahrenheit.

The South Pole Telescope’s multiyear observing campaign brings together researchers from across North America, Europe and Australia. With the upgraded telescope taking data, the exploration of the cosmic microwave background radiation enters a new era with a powerful collaboration and an extremely sensitive instrument.

“The study of the CMB involves so many different kinds of scientific journeys,” Chang said. “It’s exciting to watch efforts from all over come together to push the frontiers of what we know.”

The South Pole Telescope collaboration is led by the University of Chicago, and includes research groups at Argonne National Laboratory, Case Western Reserve University, Fermi National Accelerator Laboratory, Harvard-Smithsonian Astrophysical Observatory, Ludwig Maximilian University of Munich, McGill University, SLAC National Accelerator Laboratory, University of California at Berkeley, University of California at Davis, University of California at Los Angeles, University of Colorado at Boulder, University of Illinois at Urbana-Champaign, University of Melbourne, University of Toronto, as well as individual scientists at several other institutions.

The South Pole Telescope is funded primarily by the National Science Foundation’s Office of Polar Programs and the U.S. Department of Energy Office of Science. Partial support also is provided by the NSF-funded Physics Frontier Center at the KICP, the Kavli Foundation, and the Gordon and Betty Moore Foundation.

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, a joint partnership between the University of Chicago and the Universities Research Association Inc. Visit Fermilab’s website at www.fnal.gov and follow us on Twitter at @Fermilab.

DOE’s 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.

How can you build 150 particle detector assemblies in less than three years if the completion of one assembly takes almost two months?

This is one of the big questions that scientists and engineers working on the international Deep Underground Neutrino Experiment have to answer to meet the ambitious goal of starting data taking in 2026. And the National Science Foundation just awarded a $1.6 million grant to four U.S. universities to develop the plan.

“Building an experiment of this scale requires years of research and development,” said Denise Caldwell, director of NSF’s Division of Physics. “We are pleased that this award will enable NSF collaborators to contribute to the planning of this truly international effort.”

While this is an NSF planning award for DUNE, the foundation has a long history of investments in major particle physics experiments, including research to uncover the mysteries of neutrinos.  NSF is the primary funding source of the IceCube Neutrino Observatory, located at the South Pole. The IceCube collaboration recently announced the first evidence of a source of high-energy cosmic neutrinos, giving us a more complete understanding of the universe.

The NSF grant for DUNE expands the foundation’s pioneering and significant investments in liquid-argon neutrino detectors and physics, including early investments in the ArgoNeuT, MicroBooNE and Short-Baseline Near Detector experiments.

DUNE, supported by the U.S. Department of Energy Office of Science and hosted by the DOE’s Fermilab, will use four gigantic particle detector modules filled with a total of 70,000 tons of liquid argon to look for tracks created by neutrinos to learn more about these elusive particles and the role they play in the universe. A crucial building block of these modules are large, rectangular frames with four layers of wires on each side, called anode plane assemblies. Each APA comprises 24,000 meters of wire, wound in straight lines to record the signals created by neutrino collisions in liquid argon.

Over the past two years, DUNE collaborators have built six of these APAs, each about 6 meters long and 2.3 meters wide, for a prototype detector the size of a two-story building, assembled at CERN. The final DUNE detectors, to be installed a mile underground at the Sanford Underground Research Facility in South Dakota, each will be 20 times larger. DUNE will need 300 APAs: half of them are expected to be built by a consortium of universities at Daresbury Laboratory in the UK, which already manufactured modules for the prototype at CERN; and the other half is expected to be built at facilities in the United States.

Now with support from the NSF, scientists and engineers from the University of Chicago, Yale, Syracuse and the Physical Sciences Laboratory at the University of Wisconsin are taking the lead to finalize the design of the APAs for DUNE and figure out how a broad consortium of U.S. universities—including many more institutions than the four receiving the initial NSF grant—could collectively build 150 APAs and ship them to South Dakota for installation underground.

“Once we have finalized the design and production plan, we will submit a proposal from a broad consortium of US universities to build the 150 APAs,” said University of Chicago’s Ed Blucher, who is the lead investigator on the NSF grant and co-spokesperson of the DUNE collaboration. “It will secure a leading role for NSF-supported university groups in constructing and ultimately in extracting physics from DUNE.”

The four institutions have extensive expertise in the design and production of wire planes for liquid-argon neutrino detectors, starting more than a decade ago.

“Now it is the technology of choice for many neutrino experiments,” said Bonnie Fleming, who served as the founding spokesperson for the ArgoNeuT and MicroBooNE experiments. “At Yale’s Wright Lab, we are winding wire planes for the Short-Baseline Near Detector at Fermilab. This effort is led by Syracuse and funded by the NSF, and students and postdocs from collaborating institutions are engaged in the process.”

The four institutions also have facilities that are big enough to set up the large assembly lines for the wiring and mass production of the APAs. In fact, the Physical Sciences Laboratory built four of the six APAs installed in the first DUNE prototype detector at CERN.

“There are not many institutions that have facilities with enough floor space for this kind of work,” Blucher said. “The NSF grant allows us to figure out how to put the APA production facilities into existing buildings, how to run those factories, how to integrate students and postdocs into the project, and how to plan for the work flow.”

So how do you produce 150 APAs in less than three years?

“Setting up multiple assembly lines and increasing the efficiency of winding each APA are part of the answer,” Blucher explained. “Ultimately, the assembly of each APA must be faster while maintaining superb quality control.”

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.”