From Lawrence Berkeley National Lab: “Lead Lab Selected for Next-Generation Cosmic Microwave Background Experiment”

From Lawrence Berkeley National Lab

September 9, 2020
Glenn Roberts Jr.
(510) 520-0843

U.S. DOE selects Berkeley Lab to lead DOE/NSF experiment that combines observatories at the South Pole and in Chile’s Atacama high desert.

The South Pole Telescope scans the sky as the southern lights, or aurora australis, form green patterns in this 2018 video clip. The CMB-S4 project will feature new telescopes around this site of current experiments at the South Pole, and also in Chile’s Atacama high desert. (Credit: Robert Schwarz/University of Minnesota.)

The largest collaborative undertaking yet to explore the relic light emitted by the infant universe has taken a step forward with the U.S. Department of Energy’s selection of Lawrence Berkeley National Laboratory (Berkeley Lab) to lead the partnership of national labs, universities, and other institutions that will carry out the DOE roles and responsibilities for the effort. This next-generation experiment, known as CMB-S4, or Cosmic Microwave Background Stage 4, is being planned to become a joint DOE and National Science Foundation project.

The ‘Stage-4’ ground-based cosmic microwave background (CMB) experiment, CMB-S4, consisting of dedicated telescopes equipped with highly sensitive superconducting cameras operating at the South Pole, the high Chilean Atacama plateau, and possibly northern hemisphere sites, will provide a dramatic leap forward in our understanding of the fundamental nature of space and time and the evolution of the Universe. CMB-S4 will be designed to cross critical thresholds in testing inflation, determining the number and masses of the neutrinos, constraining possible new light relic particles, providing precise constraints on the nature of dark energy, and testing general relativity on large scales.

CMB-S4 will unite several existing collaborations to survey the microwave sky in unprecedented detail with 500,000 ultrasensitive detectors for 7 years. These detectors will be placed on 21 telescopes in two of our planet’s prime places for viewing deep space: the South Pole and the high Chilean Atacama desert. The project is intended to unlock many secrets in cosmology, fundamental physics, astrophysics, and astronomy.

Combining a mix of large and small telescopes at both sites, CMB-S4 will be the first experiment to access the entire scope of ground-based CMB science. It will measure ever-so-slight variations in the temperature and polarization, or directionality, of microwave light across most of the sky, to probe for ripples in space-time associated with a rapid expansion at the start of the universe known as Inflation.


Alan Guth, from Highland Park High School and M.I.T., who first proposed cosmic inflation


Lamda Cold Dark Matter Accerated Expansion of The universe http the-cosmic-inflation-suggests-the-existence-of-parallel-universes
Alex Mittelmann, Coldcreation

Alan Guth’s notes:

Alan Guth’s original notes on inflation

This image, from “Eternal Sky,” a video series about the Simons Observatory, shows the Atacama Desert site where some of the telescopes for the CMB-S4 experiment will be built. (Credit: Copyright Debra Kellner/Simons Foundation.)

CMB-S4 will also help to measure the mass of the neutrino; map the growth of matter clustering over time in the universe; shed new light on mysterious Dark Matter, which makes up most of the universe’s matter but hasn’t yet been directly observed, and Dark Energy, which is driving an accelerating expansion of the universe; and aid in the detection and study of powerful space phenomena like gamma-ray bursts and jet-emitting blazars.

Gamma-ray burst credit NASA SWIFT/Cruz Dewilde.

NASA Neil Gehrels Swift Observatory.

On Sept. 1, DOE Office of Science Director Chris Fall authorized the selection of Berkeley Lab as the lead laboratory for the DOE roles and responsibilities on CMB-S4, with Argonne National Laboratory, Fermi National Accelerator Laboratory, and SLAC National Accelerator Laboratory serving as partner labs.

The CMB-S4 collaboration now numbers 236 members at 93 institutions in 14 countries and 21 U.S. states.

The project passed its first DOE milestone, known as Critical Decision 0 or CD-0, on July 26, 2019. It has been endorsed by the 2014 report of the Particle Physics Project Prioritization Panel (known as P5), which helps to set the future direction of particle physics-related research. The project also was recommended in the National Academy of Sciences Strategic Vision for Antarctic Science in 2015, and by the Astronomy and Astrophysics Advisory Committee in 2017.

Berkeley Lab Director Michael Witherell said, “The community of CMB scientists has come together to form a strong collaboration with a unified vision of what is needed for the next generation of discovery,” adding, “We will work with the universities and other laboratories, supported by the DOE and the NSF, to turn this vision into a CMB observatory that has unprecedented power and resolution.”

A view of the South Pole Telescope, one of the existing instruments at the South Pole site where CMB-S4 will be built. (Credit: Argonne National Laboratory.)

The NSF has been key to the development of CMB-S4, which builds on NSF’s existing program of university-led, ground-based CMB experiments. Four of these experiments – the Atacama Cosmology Telescope and POLARBEAR/Simons Array in Chile, and the South Pole Telescope and BICEP/Keck at the South Pole – helped to start CMB-S4 in 2013, and the design of CMB-S4 relies heavily on technologies developed and deployed by these teams and others.

Princeton Atacama Cosmology Telescope, on Cerro Toco in the Atacama Desert in the north of Chile, near the Llano de Chajnantor Observatory, Altitude 4,800 m (15,700 ft).

Princeton ACT Telescope, on Cerro Toco in the Atacama Desert in the north of Chile, near the Llano de Chajnantor Observatory, Altitude 4,800 m (15,700 ft).

POLARBEAR McGill Telescope located in the Atacama Desert of northern Chile in the Antofagasta Region. The POLARBEAR experiment is mounted on the Huan Tran Telescope (HTT) at the James Ax Observatory in the Chajnantor Science Reserve.

BICEP 3 at the South Pole.

NSF is also helping to plan its possible future role with a grant awarded to the University of Chicago.

The CMB-S4 collaboration was established in 2018, and its current co-spokespeople are Julian Borrill, head of the Computational Cosmology Center at Berkeley Lab and a researcher at UC Berkeley’s Space Sciences Laboratory, and John Carlstrom, a professor of physics, astronomy, and astrophysics at the University of Chicago and scientist at Argonne Lab.

CMB-S4 builds on decades of experience with ground-based, satellite, and balloon-based experiments, and Berkeley Lab has had a prominent role in CMB research for decades, noted Natalie Roe, Berkeley Lab’s associate laboratory director for the Physical Sciences Area.

Berkeley Lab’s George Smoot, for example, shared the Nobel Prize in Physics in 2006 for leading a research team that discovered ever-slight temperature variations in the CMB light.

Adrian Lee, a Berkeley Lab physicist and UC Berkeley professor, has served on the leadership teams for a number of precursor experiments to CMB-S4, including POLARBEAR/Simons Array and the Simons Observatory. Lee noted that the Simons Observatory and POLARBEAR have contributed design elements that are relevant to CMB-S4 – such as in the areas of optics and cryogenics.

Borrill pioneered the use of supercomputers for CMB data analysis, led data management for the CMB research community for the past two decades at the DOE’s National Energy Research Scientific Computing Center (NERSC), and has served as the U.S. computational systems architect for the European Space Agency/NASA Planck satellite mission, which probed the CMB in great detail.


NERSC Cray Cori II supercomputer, named after Gerty Cori, the first American woman to win a Nobel Prize in science

NERSC Hopper Cray XE6 supercomputer, named after Grace Hopper, One of the first programmers of the Harvard Mark I computer

NERSC Cray XC30 Edison supercomputer

NERSC GPFS for Life Sciences

The Genepool system is a cluster dedicated to the DOE Joint Genome Institute’s computing needs. Denovo is a smaller test system for Genepool that is primarily used by NERSC staff to test new system configurations and software.

NERSC PDSF computer cluster in 2003.

PDSF is a networked distributed computing cluster designed primarily to meet the detector simulation and data analysis requirements of physics, astrophysics and nuclear science collaborations.


Cray Shasta Perlmutter SC18 AMD Epyc Nvidia pre-exascale supeercomputer

NERSC is a DOE Office of Science User Facility.

CMB per ESA/Planck

ESA/Planck 2009 to 2013

“What’s new about CMB-S4 is not the technology itself,” Borrill said, “but the scale at which we plan to deploy it – the sheer number of detectors, scale of the readout systems, number of telescopes, and volume of data to be processed.”

Roe noted that Berkeley Lab has particular expertise in data management, and in the design and fabrication of detectors for CMB experiments.

“This is a very big project,” Roe said. “We plan to staff up and bring in all of the expertise and capabilities from our sister labs and from the university community.”

CMB-S4 will exceed the capabilities of earlier generations of experiments by more than 10 times. It will have the combined viewing power of three large and 18 small telescopes. The major technology challenge for CMB-S4 is in its scale. While previous generations of instruments have used tens of thousands of detectors, the entire CMB-S4 project will require half a million.

The latest detector design, adapted from current experiments, will feature over 500 silicon wafers that each contain 1,000 superconducting detectors, on average – some wafers will contain up to 2,000 detectors.

This prototype wafer, measuring about 5 inches across, with over 1,000 detectors, was made to test detector fabrication processes and detector quality for the CMB-S4 experiment. (Photo courtesy of Aritoki Suzuki/Berkeley Lab)

Aritoki Suzuki, a Berkeley Lab staff scientist, who is a detector team co-lead for CMB-S4, has been working with industry to develop faster and cheaper manufacturing processes for the detectors, as an option that can be considered, and noted that multiple manufacturing sites at research institutions are needed, too.

“Delivering nearly 500,000 detectors will be one of the biggest challenges of the project,” Suzuki said. “We will combine forces from national labs, universities, and industry partners to tackle this immense task.”

Another major hardware focus for the project will be the construction of new telescopes. The data-management challenges will be substantial, too, as these huge arrays of detectors will produce 1,000 times more data than the Planck satellite.

CMB-S4 plans to draw upon computing resources at Berkeley Lab’s NERSC and the Argonne Leadership Computing Facility (ALCF), and to apply to NSF’s Open Science Grid and eXtreme Science and Engineering Discovery Environment (XSEDE).

The project is hoping to deploy its first telescope in 2027, to be fully operational at all telescopes within a couple of years, and to run through 2035.

Next steps include preparing a project office at Berkeley Lab, getting ready for the next DOE milestone, known as Critical Decision 1, working toward becoming an NSF project, and working across the community to bring in the best expertise and capabilities.

ALCF and NERSC are DOE Office of Science user facilities.

Dark Matter Background
Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, did most of the work on Dark Matter.

Fritz Zwicky from http://

Coma cluster via NASA/ESA Hubble

In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science)

Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL)

Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

The Vera C. Rubin Observatory currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

Dark Energy Survey

Dark Energy Camera [DECam], built at FNAL

NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

Timeline of the Inflationary Universe WMAP

The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

See the full article here .


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