Celebrate the unseen: Attend a Dark Matter Day event

Editor’s note: This release was issued by the international Interactions Collaboration, a group of science communicators representing the world’s particle physics laboratories. Fermilab is a member of this collaboration and is sponsoring several Dark Matter Day events. 

The world will soon be celebrating the hunt for the universe’s most elusive matter in a series of Dark Matter Day (www.darkmatterday.com) events planned in over a dozen countries.

The events, planned on and around the formally recognized day on Oct. 31, 2017, will engage the public in discussions about dark matter, which together with dark energy makes up about 95 percent of the mass and energy in our universe. Although we know through its gravitational effects that dark matter greatly dwarfs the visible matter in our universe, we know little about it.

How can I get involved? 

Universities, institutions, science centers and individuals have already announced Dark Matter Day-themed events in Austria, Brazil, Canada, Chile, Colombia, France, Germany, Italy, Mexico, Peru, Spain, Sweden, Switzerland, and in the U.K. and U.S., with more events on the way. There are also several online events planned if you can’t be there in person.

• View the full events list, a country-sorted list, or a list of online or virtual events.
• There still time to organize your own event. Check out our Event Starter Kit.
• Also, you can help promote dark matter day to your friends, colleagues, and social network. Join an online campaign (via Thunderclap) to get the word out about Dark Matter Day, and use #darkmatterday in your social posts.

What is dark matter?

Dark matter explains how galaxies spin at a faster-than-expected rate without coming apart. Scientists know from these and other space observations that there is “missing” mass — something we can’t see — that makes up an estimated 95 percent of the total mass and energy of the universe. So a big part of the universe is largely unknown to us.

Finding out what dark matter is made of is a pressing pursuit in physics. We don’t yet know if it’s composed of undiscovered particles or whether it requires some other change in our understanding of the universe’s laws of physics. A host of innovative experiments are searching for the source of dark matter using different types of tools, such as mile-deep detectors, powerful particle beams, and space-based and ground-based telescopes.

Why is there a day dedicated to dark matter?

Revealing dark matter’s true nature will tell us a lot about the origins, evolution and overall structure in the universe and will reshape our understanding of physics.

Dark Matter Day events are intended to educate the public about the importance of learning all we can about dark matter to develop a fuller picture of the unseen universe. Focusing more brain power and scientific resources on dark matter’s mysteries could lead to new ideas and new discoveries.

Who is behind Dark Matter Day?

This first-ever Dark Matter Day campaign was conceived by the Interactions Collaboration, a group of science communicators representing the world’s particle physics laboratories. The collaboration also runs the www.darkmatterday.com website as a resource for people who want to host or attend local Dark Matter Day events.

Need more help?

Members of the Interactions Collaboration want you to be a part of Dark Matter Day. Please send an email to darkmatterday@interactions.org with any questions, comments or suggestions.

For a press contact in your region visit: http://www.darkmatterday.com/contacts

The Interactions Collaboration (Interactions.org) seeks to support the international science of particle physics and to set visible footprints for peaceful collaboration across all borders. The www.darkmatter.com website was developed and is jointly maintained by the Interactions Collaboration, whose members represent the world’s particle physics laboratories and institutions in Europe, North America, Asia, and Australia, with funding provided by science funding agencies from many nations.

Editor’s note: The following press release was issued by Caltech. Fermilab is part of a continuing collaboration on this work, pursuing quantum technology for new scientific applications and discoveries. Daniel Lidar, one of the co-authors on the paper referenced in the release, will give a Colloquium talk at Fermilab on Dec. 6 as part of the Near-Term Applications of Quantum Computing conference, which Fermilab will host Dec. 6 and 7. Read more about this application at the INQNET website. 

Researchers from Caltech and the University of Southern California (USC) report the first application of quantum computing to a physics problem. By employing quantum-compatible machine learning techniques, they developed a method of extracting a rare Higgs boson signal from copious noise data. Higgs is the particle that was predicted to imbue elementary particles with mass and was discovered at the Large Hadron Collider in 2012. The new quantum machine learning method is found to perform well even with small data sets, unlike the standard counterparts.

Despite the central role of physics in quantum computing, until now, no problem of interest for physics researchers has been resolved by quantum computing techniques. In this new work, the researchers successfully extracted meaningful information about Higgs particles by programming a quantum annealer — a type of quantum computer capable of running only optimization tasks — to sort through particle measurement data littered with errors. Caltech’s Maria Spiropulu, the Shang-Yi Ch’en professor of physics, conceived the project and collaborated with Daniel Lidar, pioneer of the quantum machine learning methodology and Viterbi professor of engineering at USC who is also a distinguished Moore scholar in Caltech’s Division of Physics, Mathematics and Astronomy.

The quantum program seeks patterns within a data set to tell meaningful data from junk. It is expected to be useful for problems beyond high-energy physics. The details of the program as well as comparisons to existing techniques are detailed in a paper published on Oct. 19 in the journal Nature.

A popular computing technique for classifying data is the neural network method, known for its efficiency in extracting obscure patterns within a data set. The patterns identified by neural networks are difficult to interpret, as the classification process does not reveal how they were discovered. Techniques that lead to better interpretability are often more error-prone and less efficient.

“Some people in high-energy physics are getting ahead of themselves about neural nets, but neural nets aren’t easily interpretable to a physicist,” said USC’s physics graduate student Joshua Job, co-author of the paper and guest student at Caltech. The new quantum program is “a simple machine learning model that achieves a result comparable to more complicated models without losing robustness or interpretability,” Job said.

With prior techniques, the accuracy of classification depends strongly on the size and quality of a training set, which is a manually sorted portion of the data set. This is problematic for high-energy physics research, which revolves around rare events buried in large amount of noise data.

“The Large Hadron Collider generates a huge number of events, and the particle physicists have to look at small packets of data to figure out which are interesting,” Job said.

The new quantum program “is simpler, takes very little training data, and could even be faster. We obtained that by including the excited states,” Spiropulu said.

Excited states of a quantum system have excess energy that contributes to errors in the output.

“Surprisingly, it was actually advantageous to use the excited states, the suboptimal solutions,” Lidar said. “Why exactly that’s the case, we can only speculate. But one reason might be that the real problem we have to solve is not precisely representable on the quantum annealer. Because of that, suboptimal solutions might be closer to the truth.”

Modeling the problem in a way that a quantum annealer can understand proved to be a substantial challenge that was successfully tackled by Spiropulu’s former graduate student at Caltech, Alex Mott, who is now at DeepMind.

“Programming quantum computers is fundamentally different from programming classical computers. It’s like coding bits directly. The entire problem has to be encoded at once, and then it runs just once as programmed,” Mott said.

Despite the improvements, the researchers do not assert that quantum annealers are superior. The ones currently available are simply “not big enough to even encode physics problems difficult enough to demonstrate any advantage,” Spiropulu said.

“It’s because we’re comparing a thousand qubits — quantum bits of information — to a billion transistors,” said Jean-Roch Vlimant, a postdoctoral scholar in high-energy physics at Caltech. “The complexity of simulated annealing will explode at some point, and we hope that quantum annealing will also offer speedup.”

The researchers are actively seeking further applications of the new quantum-annealing classification technique.

“We were able to demonstrate a very similar result in a completely different application domain by applying the same methodology to a problem in computational biology,” Lidar said.

“There is another project on particle-tracking improvements using such methods, and we’re looking for new ways to examine charged particles,” Vlimant said.

“The result of this work is a physics-based approach to machine learning that could benefit a broad spectrum of science and other applications,” Spiropulu said. “There is a lot of exciting work and discoveries to be made in this emergent cross-disciplinary arena of science and technology.”

This project was supported by the United States Department of Energy, Office of High Energy Physics, Research Technology, Computational HEP, and Fermi National Accelerator Laboratory as well as the National Science Foundation. The work was also supported by the AT&T Foundry Innovation Centers through INQNET (INtelligent Quantum NEtworks and Technologies), a program for accelerating quantum technologies.

Sending bunches of protons speeding around a circular particle collider to meet at one specific point is no easy feat. Many different collider components work keep proton beams on course — and to keep them from becoming unruly.

Scientists at Fermilab invented and developed one novel collider component 20 years ago: the electron lens. Electron lenses are beams of electrons formed into specific shapes that modify the motion of other particles — usually protons — that pass through them.

The now retired Tevatron, a circular collider at Fermilab, and the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory have both benefited from electron lenses, a concept originally developed at Fermilab.

“Electron lenses are like a Swiss Army knife for accelerators: They’re relatively simple and inexpensive, but they can be applied in a wide variety of ways,” said Alexander Valishev, a Fermilab scientist who co-authored a recent study for a new electron lens application, which could be crucial to forthcoming colliders.

The innovation is detailed in an article published on Sept. 27 in Physical Review Letters. (The article was also recently selected for presentation in the Physics Central’s Physics Buzz Blog.)

“This little breakthrough in the physics of beams and accelerators is kind of a beginning of a bigger invention — it’s a new thing,” said Fermilab’s Vladimir Shiltsev, an author of the published paper. Shiltsev also played a major role in the origination of electron lenses in 1997. “Fermilab is known for inventions and developments that are, first, exciting, and then, functional. That’s what national labs are built for, and that’s what we’ve achieved.”

A lens into the future

This new type of electron lens, called the Landau damping lens, will be a critical part of a huge, prospective project in particle physics research: the Future Circular Collider at CERN. The FCC would push the boundaries of traditional collider design to further study the particle physics beyond the Higgs boson, a fundamental particle discovered only five years ago.

The proposed FCC has to be a high-luminosity machine: Its particle beams will need to be compact and densely packed. Compared with CERN’s Large Hadron Collider, the beams will also have a dramatic increase in energy — 50 trillion electronvolts, compared with the LHC’s beam energy of 7 trillion electronvolts. That involves an equally dramatic increase in the size of the accelerator. With a planned circumference of 100 kilometers, the FCC would dwarf the 27-kilometer LHC.

These high-energy, high-luminosity supercolliders all experience a problem, regardless of size: An intense beam of protons packed into the width of human hair traveling over a long distance can become unstable, especially if all the protons travel in exactly the same way.

In a collider, particles arrive in packets called bunches — roughly foot-long streams packed with hundreds of billions of particles. A particle beam is formed of dozens, hundreds or thousands of these bunches.

Imagine a circular collider as a narrow racetrack, with protons in a bunch as a tight pack of racecars. A piece of debris suddenly appears in the middle of the track, disrupting the flow of traffic. If every car reacts in the same way, say, by veering sharply to the left, it could lead to a major pileup.

Inside the collider, it’s not a matter of avoiding just one bump on the track, but adjusting to numerous dynamic obstacles, causing the protons to change their course many times over. If an anomaly, such as a kink in the collider’s magnetic field, occurs unexpectedly, and if the protons in the beam all react to it in the same way at the same time, even a slight change of course could quickly go berserk.

One could avoid the problem by thinning the particle beam from the get-go. By using lower-density proton beams, you provide less opportunity for protons to go off course. But that would mean removing protons and so missing out on potential for scientific discovery.

Another, better way to address the problem is to introduce differences into the beam so that not all the protons in the bunches behave the same way.

To return to the racetrack: If the drivers all react to the piece of debris different ways —some moving slightly to the right, others slightly to the left, one brave driver just skips over the top — the cars can all merge back together and continue the race, no accidents.

Creating differentiations within a proton bunch would do essentially the same thing. Each proton follows its own, ever-so-slightly different course around the collider. This way, any departure from the course is isolated, rather than compounded by protons all misbehaving in concert, minimizing harmful beam oscillations.

“Particles at the center of the bunch will move differently than particles around the outside,” Shiltsev said. “The protons will all be kind of messed up, but that’s what we want. If they all move together, they become unstable.”

These differences are usually created with a special type of magnet called octupoles. The Tevatron, before its decommissioning in 2011, had 35 octupole magnets, and the LHC now has 336.

But as colliders get larger and achieve greater energies, they need exponentially higher numbers of magnets: The FCC will require more than 10,000 octupole magnets, each a meter long, to achieve the same beam-stabilizing results as previous colliders.

That many magnets take up a lot of space: as much as 10 of the FCC’s 100 kilometers.

“That seems ridiculous,” Shiltsev said. “We’re looking for a way to avoid that.”

The scientific community recognizes the Landau damping nonlinear lens as a likely solution to this problem: A single one-meter-long electron lens could replace all 10,000 octupole magnets and possibly do a better job keeping beams stable as they speed toward collision, without introducing any new problems.

“At CERN they’ve embraced the idea of this new electron lens type, and people there will be studying them in further detail for the FCC,” Valishev said. “Given what we know so far about the issues that the future colliders will face, this would be a device of extremely high criticality. This is why we’re excited.”

Electron Legos

The Landau damping lens will join two other electron lens types in the repertoire of tools physicists have to modify or control beams inside a collider.

“After many years of use, people are very happy with electron lenses: It’s one of the instruments used for modern accelerators, like magnets or superconducting cavities,” Shiltsev said. “Electron lenses are just one of the building blocks or Lego pieces.”

Electron lenses are a lot like Legos: Lego pieces are made of the same material and can be the same color, but a different shape determines how they can be used. Electron lenses are all made of clouds of electrons, shaped by magnetic fields. The shape of the lens dictates how the lens influences a beam of protons.

Scientists developed the first electron lens at Fermilab in 1997 for use to compensate for so-called beam-beam effects in the Tevatron, and a similar type of electron lens is still in use at the Brookhaven’s RHIC.

In circular colliders, particle beams pass by each other, going in opposing directions inside the collider until they are steered into a collision at specific points. As the beams buzz by one another, they exert a small force on each other, which causes the proton bunches to expand slightly, decreasing their luminosity.

That first electron lens, called the beam-beam compensation lens, was created to combat the interaction between the beams by squeezing them back to their original, compact state.

After the success of this electron lens type in the Tevatron, scientists realized that electron beams could be shaped a second way to create another type of electron lens.

Scientists designed the second lens to be shaped like a straw, allowing the proton beam to pass through the inside unaffected. The occasional proton might try to leave its group and stray from the center of the beam. In the LHC, losing even one-thousandth of the total number of protons in an uncontrolled way could be dangerous. The electron lens acts as a scraper, removing these rogue particles before they could damage the collider.

“It’s extremely important to have the ability to scrape these particles because their energy is enormous,” Shiltsev said. “Uncontrolled, they can drill holes, break magnets or produce radiation.”

Both types of electron lens have made their mark in collider design as part of the success of the Tevatron, RHIC and the LHC. The new Landau damping lens may help usher in the next generation of colliders.

“The electron lens is an example of something that was invented here at Fermilab 20 years ago,” Shiltsev said. “This is a one of the rare technologies that wasn’t just brought to perfection at Fermilab: It was invented, developed and perfected and still continues to shine.”

 

As you walk down the stairs from the main floor of Wilson Hall (cafeteria area) to the auditorium lobby, look up to the near edge of the wood block ceiling. Slightly west of the center line is a “hole” where a wooden block supposedly should be. I have often observed this hole since the ceiling was finished about 1973 and can attest that a block has been missing ever since. (Over time a few other distant pieces have gotten lost but should not be confused with this one.)

For me this has raised two issues:

1. Was this just a mistake in assembling the structure and never corrected or
2. Was this done on purpose to destroy any symmetry that might exist in this ceiling?

Obviously, the first issue is trivial except that it gives a plausible alternative to the second issue which is certainly more intriguing.

Fermilab founding director Bob Wilson appreciated the concept of “Broken Symmetry.” He designed a sculpture with this name, and it stands at the Pine Street entrance to the laboratory. He also gave a conference dinner talk, “Symmetry in Art and Science.” In it he discussed an artist dilemma of making something too perfect: “Only the gods are perfect.” Therefore ancient Asian artists would leave a small flaw in their work, he said. Did Wilson do the same here? I guess we will never know but the possibility is interesting.

Or, is it an omen of missing pieces in our physics knowledge?

Note: The wood for this ceiling and supposedly throughout the auditorium is walnut. It was gotten from several walnut trees that were cut down by vandals during the very early days of NAL. They were soon after captured by the FBI and the wood recovered. See the Fermilab history website.

Charles Schmidt is a Fermilab scientist emeritus.

Scientists using the Dark Energy Camera have captured images of the aftermath of a neutron star collision, the source of LIGO/Virgo’s most recent gravitational wave detection

A team of scientists using the Dark Energy Camera (DECam), the primary observing tool of the Dark Energy Survey, was among the first to observe the fiery aftermath of a recently detected burst of gravitational waves, recording images of the first confirmed explosion from two colliding neutron stars ever seen by astronomers.

Scientists on the Dark Energy Survey joined forces with a team of astronomers based at the Harvard-Smithsonian Center for Astrophysics (CfA) for this effort, working with observatories around the world to bolster the original data from DECam. Images taken with DECam captured the flaring-up and fading over time of a kilonova — an explosion similar to a supernova, but on a smaller scale — that occurs when collapsed stars (called neutron stars) crash into each other, creating heavy radioactive elements.

This particular violent merger, which occurred 130 million years ago in a galaxy near our own (NGC 4993), is the source of the gravitational waves detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo collaborations on Aug. 17. This is the fifth source of gravitational waves to be detected — the first one was discovered in September 2015, for which three founding members of the LIGO collaboration were awarded the Nobel Prize in physics two weeks ago.

This latest event is the first detection of gravitational waves caused by two neutron stars colliding and thus the first one to have a visible source. The previous gravitational wave detections were traced to binary black holes, which cannot be seen through telescopes. This neutron star collision occurred relatively close to home, so within a few hours of receiving the notice from LIGO/Virgo, scientists were able to point telescopes in the direction of the event and get a clear picture of the light.

“This is beyond my wildest dreams,” said Marcelle Soares-Santos, formerly of the U.S. Department of Energy’s Fermi National Accelerator Laboratory and currently of Brandeis University, who led the effort from the Dark Energy Survey side. “With DECam we get a good signal, and we can show how it is evolving over time. The team following these signals is a well-oiled machine, and though we did not expect this to happen so soon, we were ready for it.”

The Dark Energy Camera is one of the most powerful digital imaging devices in existence. It was built and tested at Fermilab, the lead laboratory on the Dark Energy Survey, and is mounted on the National Science Foundation’s 4-meter Blanco telescope, part of the Cerro Tololo Inter-American Observatory in Chile, a division of the National Optical Astronomy Observatory. The DES images are processed at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign.

Texas A&M University astronomer Jennifer Marshall was observing for DES at the Blanco telescope during the event, while Fermilab astronomers Douglas Tucker and Sahar Allam were coordinating the observations from Fermilab’s Remote Operations Center.

“It was truly amazing,” Marshall said. “I felt so fortunate to be in the right place at the right time to help make perhaps one of the most significant observations of my career.”

The kilonova was first identified in DECam images by Ohio University astronomer Ryan Chornock, who instantly alerted his colleagues by email. “I was flipping through the raw data, and I came across this bright galaxy and saw a new source that was not in the reference image [taken previously],” he said. “It was very exciting.”

Once the crystal clear images from DECam were taken, a team led by Professor Edo Berger, from CfA, went to work analyzing the phenomenon using several different resources. Within hours of receiving the location information, the team had booked time with several observatories, including NASA’s Hubble Space Telescope and Chandra X-ray Observatory.

LIGO/Virgo works with dozens of astronomy collaborations around the world, providing sky maps of the area where any detected gravitational waves originated. The team from DES and CfA had been preparing for an event like this for more than two years, forging connections with other astronomy collaborations and putting procedures in place to mobilize as soon as word came down that a new source had been detected. The result is a rich data set that covers “radio waves to X-rays to everything in between,” Berger said.

“This is the first event, the one everyone will remember,” Berger said. “I’m extremely proud of our entire group, who responded in an amazing way. I kept telling them to savor the moment. How many people can say they were there at the birth of a whole new field of astronomy?”

Adding to the excitement of this observation, this latest gravitational wave detection correlates to a burst of gamma rays spotted by NASA’s Fermi Gamma-ray Space Telescope. Combining these detections is like hearing thunder and seeing lightning for the very first time, and it opens up a world of new scientific discovery.

“Each of these — the gravitational waves from merging neutron stars, the gamma ray burst and the optical counterpart — could have been separate groundbreaking discoveries, and each could have taken many years,” said Daniel Holz of the University of Chicago, who works on both the DES and LIGO collaborations. “In less than a day, we did it all. This has required many different communities working together to make it all happen. It’s so gratifying to have it be so successful.”

This event also provides a completely new and unique way to measure the present expansion rate of the universe, the Hubble constant, something theorized by Holz and others. Just as astrophysicists use supernovae as “standard candles” (objects of the same intrinsic brightness) to measure cosmic expansion, kilonovae can be used as “standard sirens” (objects of known gravitational wave strength).

LIGO/Virgo can use this to tell the distance to these events, while optical follow-up from DES and others determines the red shift or recession speed; their combination enables scientists to determine the present expansion rate. This new kind of measurement will assist the Dark Energy Survey in its mission to uncover more about dark energy, the mysterious force accelerating the expansion of the universe.

“The Dark Energy Survey team has been working with LIGO for more than two years, refining their process of following up gravitational wave signals,” said Fermilab Director Nigel Lockyer. “It is immensely gratifying to be on the front lines of a discovery this significant, one that required the combined skills of many supremely talented people in many fields.”

The Dark Energy Survey recently began the fifth and final year of its quest to map an area of the southern sky in unprecedented detail. Scientists on DES will use this data to learn more about the effect of dark energy over eight billion years of the universe’s history, in the process measuring 300 million galaxies, 100,000 galaxy clusters and 3,000 supernovae.

Six papers relating to the DECam discovery of the optical counterpart are planned for publication in The Astrophysical Journal. Preprints of all papers are available here: https://www.darkenergysurvey.org/des-gravitational-waves-papers.

“It is tremendously exciting to experience a rare event that transforms our understanding of the workings of the universe,” said France A. Córdova, director of the National Science Foundation (NSF), which funds LIGO and supports the observatory where DECam is housed. “This discovery realizes a long-standing goal many of us have had — that is, to simultaneously observe rare cosmic events using both traditional as well as gravitational-wave observatories. Only through NSF’s four-decade investment in gravitational-wave observatories, coupled with telescopes that observe from radio to gamma-ray wavelengths, are we able to expand our opportunities to detect new cosmic phenomena and piece together a fresh narrative of the physics of stars in their death throes.”

 

 

The Dark Energy Survey is a collaboration of more than 400 scientists from 26 institutions in seven countries. Funding for the DES Projects has been provided by the U.S. Department of Energy Office of Science, U.S. National Science Foundation, Ministry of Science and Education of Spain, Science and Technology Facilities Council of the United Kingdom, Higher Education Funding Council for England, ETH Zurich for Switzerland, National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, Kavli Institute of Cosmological Physics at the University of Chicago, Center for Cosmology and AstroParticle Physics at Ohio State University, Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and Ministério da Ciência e Tecnologia, Deutsche Forschungsgemeinschaft, and the collaborating institutions in the Dark Energy Survey, the list of which can be found at www.darkenergysurvey.org/collaboration. 

Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science 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.

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.