Caltech Physicist Wins $3 Million Fundamental Physics Prize

New award is largest academic prize in the world

PASADENA, Calif.—Alexei Kitaev, professor of theoretical physics, computer science, and mathematics at the California Institute of Technology (Caltech), has been named an inaugural winner of the Fundamental Physics Prize—a $3 million award that represents the largest academic prize given to an individual in the history of science.

The prize, funded by Yuri Milner, a Russian entrepreneur and venture capitalist, was given with "the aim of providing the recipients with more freedom and opportunity to pursue even greater future accomplishments," according to the Fundamental Physics Prize Foundation website. In addition to Kitaev, eight other physicists received the award, for a grand total of $27 million in prize money. The individual awards are more than twice what Nobel laureates receive, and that amount—about $1.2 million—is often split among a few winners.

"It was a great surprise and honor to learn that I was a recipient of the prize along with some very famous and renowned physicists," says Kitaev. "At first, I was confused because I didn't think that the money could be just for me—I assumed such a big prize would be shared among all the recipients. I feel very happy and extremely lucky."

Kitaev, a member of the new Institute for Quantum Information and Matter (IQIM) at Caltech, is known for developing algorithms and theories to enable quantum computing, which has the potential to perform in seconds certain tasks that would take an ordinary computer thousands of years to complete. The award citation recognized his "theoretical idea of implementing robust quantum memories and fault-tolerant quantum computation using topological quantum phases with anyons and unpaired Majorana modes."

"I'm delighted that Alexei is getting the recognition he so richly deserves for making the fundamental and profound contributions to one of the most exciting areas of fundamental physics," says Tom Soifer, professor of physics and chair of the Division of Physics, Mathematics and Astronomy at Caltech. "His work is blazing the path toward what we hope will be the next major technical revolution in computing, the realization of quantum computers."

With a joint appointment at Caltech in the Division of Physics, Mathematics and Astronomy and the Division of Engineering and Applied Science, Kitaev explores the mysterious behavior of quantum systems and their implications for developing practical applications, such as quantum computers.

"Every physicist is excited to get new opportunities to test theories, and quantum computing would eliminate a lot of stumbling blocks that we face in making connections between theory and experiments," says Kitaev, who was named a MacArthur Fellow in 2008. He is unsure how he will use the prize money. Beyond his family needs and personal spending, he would like to help support educational efforts.

Kitaev received an MS from the Moscow Institute of Physics and Technology in 1986 and his PhD from Russia's Landau Institute for Theoretical Physics in 1989, where he continued to work until 1998. He was a researcher at Microsoft Research from 1999 until 2001 and spent a year at Microsoft Station Q in 2005–2006. He first came to Caltech as a visiting associate and lecturer in 1998, and he was named professor of theoretical physics and computer science in 2002.

Milner chose the inaugural recipients of the prize, but these recipients will work together to choose next year's winner, or winners. The recipients are also invited to give annual public lectures as part of an effort to raise the profile of fundamental physics and communicate advances to a wider audience.

The other winners are Nima Arkani-Hamed, Juan Maldacena, Nathan Seiberg, and Edward Witten from the Institute for Advanced Study at Princeton University; Alan Guth from MIT; Maxim Kontsevich from the Institute of Advanced Scientific Studies in France; Andrei Linde from Stanford; and Ashoke Sen from the Harish-Chandra Research Institute in India.

Caltech's IQIM is a Physics Frontier Center supported by the National Science Foundation and the Gordon and Betty Moore Foundation.

Katie Neith
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Physicist Wins $3 Million Physics Prize
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White House Honors Caltech and JPL Scientists and Engineers

White House Honors Caltech and JPL Scientists and Engineers with the Presidential Early Career Award

PASADENA, Calif.—Chiara Daraio, professor of aeronautics and applied physics, and Christopher Hirata, professor of astrophysics, both at the California Institute of Technology (Caltech), and Ian Clark of NASA's Jet Propulsion Laboratory (JPL)—which is managed by Caltech—are winners of the Presidential Early Career Award for Scientists and Engineers. This is the highest award given by the United States government to science and engineering professionals in the early stages of their independent research careers.

Daraio was recognized by the Department of Defense for her "pioneering contributions to nonlinear mechanical phenomena in acoustic crystals, granular material, and multifunctional nanostructures, and for mentoring women and providing research opportunities for high school and undergraduate students."

Daraio arrived at Caltech in 2006. She leads a research group that focuses on the design, realization, and testing of materials with novel mechanical properties. Materials developed by Daraio's research group can be used in impact-mitigation systems, in protecting mechanical systems from undesired vibrations, and in new biomedical devices for imaging and diagnostics.

"I am very excited about this award. I wanted to be an inventor and engineer early on. I came to the U.S. as a graduate student and am grateful that here I could pursue my dreams," says Daraio. "Caltech has provided me with an excellent environment to realize my ideas, working with the world's best students, postdocs, and colleagues on the faculty."

"The entire Caltech community is proud to see Professor Daraio recognized with this presidential honor, not only for her pioneering research accomplishments, but also for her commitment to students and diversity," says Ares J. Rosakis, chair of Caltech's Division of Engineering and Applied Science, Theodore von Kármán Professor of Aeronautics, and professor of mechanical engineering. "Even though she is near the beginning of her career she already embodies the key attributes of the Division of Engineering and Applied Science at Caltech."

Daraio added, "This has been a very special year for me: I had a baby just two months ago, and a few weeks earlier became a U.S. citizen. The Presidential Early Career Award is the icing on the cake."

Daraio was born in Italy and received a degree in mechanical engineering from the Marche Polytechnic University in Ancona. She received both an MS and PhD in materials science and engineering from the University of California, San Diego.

Hirata was recognized by the Department of Energy for "innovative work reducing astrophysical uncertainties that limit the extraction of fundamental physics parameters from cosmological observations, for studies of the sensitivity of structure formation to the relative velocity between dark matter and baryons in the early universe, and for service on NASA/DOE Joint Dark Energy Mission working groups."

Hirata received his BS from Caltech in 2001, a time in which significant discoveries were being made in cosmology and high-energy physics. These discoveries guided him toward further studies into topics such as what happened in the first fraction of a second in the life of the universe, how galaxies are formed, and the fundamental nature and geometry of the universe. He earned his PhD at Princeton University and returned to Caltech as a faculty member in 2007.

"In the past decade, cosmology has been revolutionized by ever-improving observational capabilities. My colleagues and I have been developing the theoretical tools that enable us to connect the direct observables—the cosmic microwave background and the distribution of galaxies—to the underlying physical processes that occurred during the first fraction of a second after the big bang," says Hirata.

"I'm extremely pleased to see the national recognition of Chris Hirata's promise and achievement," says B. Thomas Soifer, chair of Caltech's Division of Physics, Mathematics and Astronomy, director of the Spitzer Science Center, and professor of physics. "His work is vital to our understanding of the formation and evolution of structures, such as galaxies, in the universe, and the award recognizes his leadership in this area."

"When I received word about winning this award, I was in the middle of debugging software code, so the work continues," Hirata says. "But it's nice to take a step back and see how far we have come. "

Clark was recognized by NASA for "exceptional leadership and achievement in the pursuit of advanced entry, descent and landing technologies and techniques for space-exploration missions."

"It's certainly quite an honor," says Clark. "However, there are remarkable achievements every day here at JPL/Caltech that are equally deserving of recognition. I wish we could honor the JPL and NASA teams for the amazing work on the Mars Science Laboratory as we prepare for it to land on Mars." 

"Discoveries in science and technology not only strengthen our economy, they inspire us as a people." President Obama said. "The impressive accomplishments of today's awardees so early in their careers promise even greater advances in the years ahead. "

The Presidential Early Career Award for Scientists and Engineers was established by President Clinton in 1996 and is coordinated by the President's Office of Science and Technology Policy. Awardees are selected for their pursuit of innovative research at the frontiers of science and technology, and their commitment to community service as demonstrated through scientific leadership, public education, or community outreach. Fourteen Caltech professors and researchers have won the award since its inception.

Caltech is recognized for its highly select student body of approximately 1,000 undergraduates and 1,300 graduate students, and for its outstanding faculty. Since 1923, Caltech faculty and alumni have garnered 32 Nobel Prizes and seven Crafoord Prizes. In addition to its prestigious on-campus research programs, Caltech operates the Jet Propulsion Laboratory (JPL); the W. M. Keck Observatory on Mauna Kea, in Hawaii; the Palomar Observatory; and the Laser Interferometer Gravitational-Wave Observatory (LIGO). Caltech is a private university in Pasadena, California. For more information, visit

Brian Bell
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Caltech Physicists are Awarded New Funding from the Simons Foundation

For nearly 20 years, the Simons Foundation has worked to advance mathematics and the physical sciences through grants and educational programs. Now the organization is taking its support of research one step further by naming 21 scientists as the first-ever Simons Investigators. Caltech physicists Chris Hirata and Hirosi Ooguri are among this inaugural group of recipients, each of whom are eligible to receive more than $1.3 million over the next ten years to fund innovative research.

According to the foundation, the goal of the new program is "to provide a stable base of support for outstanding scientists in their most productive years, enabling them to undertake long-term study of fundamental questions." Nine theoretical physicists, seven mathematicians, and five computer scientists were appointed as Simons Investigators. Each recipient will be granted funds to be applied to their individual research, their department, and their institution for an initial period of five years, beginning in August. The foundation anticipates renewing the grants for an additional five years in 2017.

Hirosi Ooguri, the Fred Kavli Professor of Theoretical Physics and Mathematics at Caltech and deputy chair of the Division of Physics, Mathematics and Astronomy, was recognized in his award citation as a "mathematical physicist and string theorist of exceptional creativity and breadth." He was chosen as an investigator for his "innovations in the use of topological string theory to compute Feynman diagrams in superstring models," as well as for his cutting-edge work on the relationship of supersymmetric gauge theories to string theory and to gravity.

"Theoretical physicists are like travelers without maps—to bring back wonderful things from far places, we need to take a long view and take risks," says Ooguri, who has been at Caltech since 2000. "The stable and unrestricted support from the Simons Investigator program will enable us to make such long journeys. I am excited about the opportunity and will try my best to live up to the expectation."

Chris Hirata, professor of astrophysics, was cited as "an outstanding young cosmologist and astrophysicist whose research ranges from purely theoretical investigations to original data analysis." He will receive funding for his work with experimental and observational groups on systematizing the extraction of cosmological data from the cross correlation of different extragalactic surveys—work that "is having an important impact on precision cosmology," according to the foundation.

"We are very proud that the Simons Foundation has recognized two of our outstanding faculty in theoretical physics through these awards," says Thomas Soifer, professor of physics, and chair of the Division of Physics, Mathematics and Astronomy at Caltech. "The Simons Foundation is visionary in recognizing the importance of significant, stable funding for these brilliant researchers, which will give them the resources so that they are limited in what they achieve only by their own imaginations."

The Simons Foundation is a private foundation based in New York City and was founded by mathematician James Simons and his wife, Marilyn. The organization also promotes research in the life sciences and launched the Simons Foundation Autism Research Initiative (SFARI), a program designed to improve the diagnosis and treatment of autism spectrum disorders. SFARI is a funding source for a number of research projects at Caltech.

Katie Neith
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A New Kind of Amplifier

Caltech researchers develop instrument for exploring the cosmos and the quantum world

PASADENA, Calif.—Researchers at the California Institute of Technology (Caltech) and NASA's Jet Propulsion Laboratory (JPL) have developed a new type of amplifier for boosting electrical signals. The device can be used for everything from studying stars, galaxies, and black holes to exploring the quantum world and developing quantum computers.

"This amplifier will redefine what it is possible to measure," says Jonas Zmuidzinas, Caltech's Merle Kingsley Professor of Physics, the chief technologist at JPL, and a member of the research team.

An amplifier is a device that increases the strength of a weak signal. "Amplifiers play a basic role in a wide range of scientific measurements and in electronics in general," says Peter Day, a visiting associate in physics at Caltech and a principal scientist at JPL. "For many tasks, current amplifiers are good enough. But for the most demanding applications, the shortcomings of the available technologies limit us." 

Conventional transistor amplifiers—like the ones that power your car speakers—work for a large span of frequencies. They can also boost signals ranging from the faint to the strong, and this so-called dynamic range enables your speakers to play both the quiet and loud parts of a song. But when an extremely sensitive amplifier is needed—for example, to boost the faint, high-frequency radio waves from distant galaxies—transistor amplifiers tend to introduce too much noise, resulting in a signal that is more powerful but less clear.

One type of highly sensitive amplifier is a parametric amplifier, which boosts a weak input signal by using a strong signal called the pump signal. As both signals travel through the instrument, the pump signal injects energy into the weak signal, therefore amplifying it.

About 50 years ago, Amnon Yariv, Caltech's Martin and Eileen Summerfield Professor of Applied Physics and Electrical Engineering, showed that this type of amplifier produces as little noise as possible: the only noise it must produce is the unavoidable noise caused by the jiggling of atoms and waves according to the laws of quantum mechanics. The problem with many parametric amplifiers and sensitive devices like it, however, is that they can only amplify a narrow frequency range and often have a poor dynamic range.

But the Caltech and JPL researchers say their new amplifier, which is a type of parametric amplifier, combines only the best features of other amplifiers. It operates over a frequency range more than ten times wider than other comparably sensitive amplifiers, can amplify strong signals without distortion, and introduces nearly the lowest amount of unavoidable noise. In principle, the researchers say, design improvements should be able to reduce that noise to the absolute minimum. Versions of the amplifier can be designed to work at frequencies ranging from a few gigahertz to a terahertz (1,000 GHz). For comparison, a gigahertz is about 10 times greater than commercial FM radio signals in the U.S., which range from about 88 to 108 megahertz (1 GHz is 1,000 MHz).

"Our new amplifier has it all," Zmuidzinas says. "You get to have your cake and eat it too."

The team recently described the new instrument in the journal Nature Physics.

One of the key features of the new parametric amplifier is that it incorporates superconductors—materials that allow an electric current to flow with zero resistance when lowered to certain temperatures. For their amplifier, the researchers are using titanium nitride (TiN) and niobium titanium nitride (NbTiN), which have just the right properties to allow the pump signal to amplify the weak signal.

Although the amplifier has a host of potential applications, the reason the researchers built the device was to help them study the universe. The team built the instrument to boost microwave signals, but the new design can be used to build amplifiers that help astronomers observe in a wide range of wavelengths, from radio waves to X rays.

For instance, the team says, the instrument can directly amplify radio signals from faint sources like distant galaxies, black holes, or other exotic cosmic objects. Boosting signals in millimeter to submillimeter wavelengths (between radio and infrared) will allow astronomers to study the cosmic microwave background—the afterglow of the big bang—and to peer behind the dusty clouds of galaxies to study the births of stars, or probe primeval galaxies. The team has already begun working to produce such devices for Caltech's Owens Valley Radio Observatory (OVRO) near Bishop, California, about 250 miles north of Los Angeles. 

These amplifiers, Zmuidzinas says, could be incorporated into telescope arrays like the Combined Array for Research in Millimeter-wave Astronomy at OVRO, of which Caltech is a consortium member, and the Atacama Large Millimeter/submillimeter Array in Chile.

Instead of directly amplifying an astronomical signal, the instrument can be used to boost the electronic signal from a light detector in an optical, ultraviolet, or even X-ray telescope, making it easier for astronomers to tease out faint objects.

Because the instrument is so sensitive and introduces minimal noise, it can also be used to explore the quantum world. For example, Keith Schwab, a professor of applied physics at Caltech, is planning to use the amplifier to measure the behavior of tiny mechanical devices that operate at the boundary between classical physics and the strange world of quantum mechanics. The amplifier could also be used in the development quantum computers—which are still beyond our technological reach but should be able to solve some of science's hardest problems much more quickly than any regular computer.

"It's hard to predict what all of the applications are going to end up being, but a nearly perfect amplifier is a pretty handy thing to have in your bag of tricks," Zmuidzinas says. And by creating their new device, the researchers have shown that it is indeed possible to build an essentially perfect amplifier. "Our instrument still has a few rough edges that need polishing before we would call it perfect, but we think our results so far show that we can get there."

The title of the Nature Physics paper is "A wideband, low-noise superconducting amplifier with high dynamic range." In addition to Zmuidzinas and Day, the other authors of the paper are Byeong Ho Eom, an associate research engineer at Caltech, and Henry LeDuc, a senior research scientist at JPL. This research was supported by NASA, the Keck Institute for Space Studies, and the JPL Research and Technology Development program.

Marcus Woo
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Peering Into the Heart of a Supernova

Caltech simulation points out how to detect a rapidly spinning stellar core

PASADENA, Calif.—Each century, about two massive stars in our own galaxy explode, producing magnificent supernovae. These stellar explosions send fundamental, uncharged particles called neutrinos streaming our way and generate ripples called gravitational waves in the fabric of space-time. Scientists are waiting for the neutrinos and gravitational waves from about 1,000 supernovae that have already exploded at distant locations in the Milky Way to reach us. Here on Earth, large, sensitive neutrino and gravitational-wave detectors have the ability to detect these respective signals, which will provide information about what happens in the core of collapsing massive stars just before they explode.

If we are to understand that data, however, scientists will need to know in advance how to interpret the information the detectors collect. To that end, researchers at the California Institute of Technology (Caltech) have found via computer simulation what they believe will be an unmistakable signature of a feature of such an event: if the interior of the dying star is spinning rapidly just before it explodes, the emitted neutrino and gravitational-wave signals will oscillate together at the same frequency.

"We saw this correlation in the results from our simulations and were completely surprised," says Christian Ott, an assistant professor of theoretical astrophysics at Caltech and the lead author on a paper describing the correlation, which appears in the current issue of the journal Physical Review D. "In the gravitational-wave signal alone, you get this oscillation even at slow rotation. But if the star is very rapidly spinning, you see the oscillation in the neutrinos and in the gravitational waves, which very clearly proves that the star was spinning quickly—that's your smoking-gun evidence."

Scientists do not yet know all the details that lead a massive star—one that is at least 10 times as massive as the Sun—to become a supernova. What they do know (which was first hypothesized by Caltech astronomer Fritz Zwicky and his colleague Walter Baade in 1934) is that when such a star runs out of fuel, it can no longer support itself against gravity's pull, and the star begins to collapse in upon itself, forming what is called a proto-neutron star. They also now know that another force, called the strong nuclear force, takes over and leads to the formation of a shock wave that begins to tear the stellar core apart. But this shock wave is not energetic enough to completely explode the star; it stalls part way through its destructive work.

There needs to be some mechanism—what scientists refer to as the "supernova mechanism"—that completes the explosion. But what could revive the shock? Current theory suggests several possibilities. Neutrinos could do the trick if they were absorbed just below the shock, re-energizing it. The proto-neutron star could also rotate rapidly enough, like a dynamo, to produce a magnetic field that could force the star's material into an energetic outflow, called a jet, through its poles, thereby reviving the shock and leading to explosion. It could also be a combination of these or other effects. The new correlation Ott's team has identified provides a way of determining whether the core's spin rate played a role in creating any detected supernova.

It would be difficult to glean such information from observations using a telescope, for example, because those provide only information from the surface of the star, not its interior. Neutrinos and gravitational waves, on the other hand, are emitted from inside the stellar core and barely interact with other particles as they zip through space at the speed of light. That means they carry unaltered information about the core with them. 

The ability neutrinos have to pass through matter, interacting only ever so weakly, also makes them notoriously difficult to detect. Nonetheless, neutrinos have been detected: twenty neutrinos from Supernova 1987a in the Large Magellanic Cloud were detected in February 1987. If a supernova went off in the Milky Way, it is estimated that current neutrino detectors would be able to pick up about 10,000 neutrinos. In addition, scientists and engineers now have detectors—such as the Laser Interferometer Gravitational-Wave Observatory, or LIGO, a collaborative project supported by the National Science Foundation and managed by Caltech and MIT—in place to detect and measure gravitational waves for the first time.

Ott's team happened across the correlation between the neutrino signal and the gravitational-wave signal when looking at data from a recent simulation. Previous simulations focusing on the gravitational-wave signal had not included the effect of neutrinos after the formation of a proto-neutron star. This time around, they wanted to look into that effect. 

"To our big surprise, it wasn't that the gravitational-wave signal changed significantly," Ott says. "The big new discovery was that the neutrino signal has these oscillations that are correlated with the gravitational-wave signal." The correlation was seen when the proto-neutron star reached high rotational velocities—spinning about 400 times per second.

Future simulation studies will look in a more fine-grained way at the range of rotation rates over which the correlated oscillations between the neutrino signal and the gravitational-wave signal occur. Hannah Klion, a Caltech undergraduate student who recently completed her freshman year, will conduct that research this summer as a Summer Undergraduate Research Fellowship (SURF) student in Ott's group. When the next nearby supernova occurs, the results could help scientists elucidate what happens in the moments right before a collapsed stellar core explodes.

In addition to Ott, other Caltech authors on the paper, "Correlated Gravitational Wave and Neutrino Signals from General-Relativistic Rapidly Rotating Iron Core Collapse," are Ernazar Abdikamalov, Evan O'Connor, Christian Reisswig, Roland Haas, and Peter Kalmus. Steve Drasco of the California Polytechnic State University in San Luis Obispo, Adam Burrows of Princeton University, and Erik Schnetter of the Perimeter Institute for Theoretical Physics in Ontario, Canada, are also coauthors. Ott is an Alfred P. Sloan Research Fellow.

Most of the computations were completed on the Zwicky Cluster in the Caltech Center for Advanced Computing Research. Ott built the cluster with a grant from the National Science Foundation. It is supported by the Sherman Fairchild Foundation.

Kimm Fesenmaier
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Physicists Discover a New Particle that May Be the Higgs Boson

International consortium of scientists includes a large Caltech contingent

PASADENA, Calif.—Physicists at the Large Hadron Collider (LHC) in Geneva, Switzerland, have discovered a new particle that may be the long-sought Higgs boson, the fundamental particle that is thought to endow elementary particles with mass. 

"This is a momentous time in the history of particle physics and in scientific exploration—the implications are profound," says Harvey Newman, professor of physics at the California Institute of Technology (Caltech). "This is experimental science at its best."

The international team of scientists and engineers—which includes a large contingent from Caltech, led by Newman and Maria Spiropulu, professor of physics—says it needs more data to determine for certain if the particle they've discovered is indeed the Higgs boson predicted by the Standard Model, the theory that describes how all particles interact. The results so far, however, show that it has many of the properties expected for such a particle. 

"One of the most exciting aspects of this observation is that the road remains open for a vast range of 'lookalike' alternatives, where any deviation from the Standard Model would point the way to the existence of other new particles or forces of nature," Newman says.

Regardless of the exact identity of the new particle, CERN's scientists say, the highly anticipated discovery heralds a new era in physics.

The physicists revealed their latest results at a seminar at the European Center for Nuclear Research (CERN) in Geneva, which was shared with the world with a live webcast and the EVO (Enabling Virtual Organizations) system developed at Caltech.

The discovery itself is based on the analysis of an unprecedented amount of data that was collected by the two main detectors at the LHC—the Compact Muon Solenoid (CMS) and A Toroidal LHC Apparatus (ATLAS). The data was collected with the LHC running at 7 teraelectron volts (TeV, a unit of energy) in 2011 and 8 TeV in 2012. The Caltech team is part of the CMS collaboration.

Using the CMS detector, the physicists identified signals that point to a new particle with a mass of 125 gigaelectron volts (GeV, a unit of mass; in comparison, the mass of a proton is about 1 GeV). The team running the ATLAS detector, which searches for the Higgs using a different method, reported similar results.

"This is an incredible, exciting moment," says Spiropulu. "Even these early results give us important hints as to how mass in the universe came to be. Together with hundreds of our colleagues Caltech scientists have worked for decades to reach this point: building multiple generations of experiments; designing and building detectors to precisely measure photons, electrons, and muons, which are keys to the discovery; and inventing worldwide systems that empower thousands of physicists throughout the world to collaborate day and night, share and analyze the data, and develop the new techniques leading to this great result."

To search for the Higgs, physicists have had to comb through the remains of trillions of particle collisions produced by the LHC, which accelerates protons around a ring almost five miles wide to nearly the speed of light. As the protons careen toward each other, a small fraction of them collide, creating other particles such as the Higgs. It is estimated that it takes one billion collisions to make just one Higgs boson.

The Higgs is fleeting, however, and quickly decays into lighter particles, which are the traces that allow the Higgs to be detected and analyzed. The Higgs is predicted to decay in several different ways, or channels, each resulting in different particles. CMS focuses mainly on the decay channels that result in two photons or two other particles called Z bosons. It was by measuring and analyzing these and other decay particles that the physicists were able to discover the potential Higgs.

When all the decays are taken into account in combination, the scientists announced, the data for a signal corresponding to a Standard Model Higgs boson have a statistical significance of five sigmas. This means the signal is highly unlikely to be the result of a statistical fluke caused by some rare, background fluctuation. Only when data are significant to five sigmas are physicists confident enough to declare a discovery.

Last December, evidence seen in the data from CMS generated plenty of excitement as a result of an excess of events—a slight surplus in particle collision events over what would have been expected if the Higgs does not exist—with a statistical significance of just three sigmas.

The Higgs boson is the last remaining fundamental particle predicted by the Standard Model yet to be detected, and hopes of detecting it was one of the chief reasons for building the LHC. The LHC accelerator, along with the CMS and ATLAS experiments, are arguably the largest and most complex scientific instruments ever built.

Despite its many successes, the Standard Model is incomplete—it does not incorporate gravity or dark matter, for example. One of the goals of physicists, then, is to develop more complete theories that better explain the composition of the universe and what happened during the first moments after the Big Bang. Discovering the Higgs boson—or a particle like it—is essential for developing these new theories.

The measurements of the new particle, the physicists say, are so far consistent—within statistical uncertainty—with the Higgs boson as predicted by the Standard Model. Still, they need more data to know for sure whether it is the predicted Higgs or something stranger, a Higgs lookalike—a prospect that many theorists have long been anticipating.  

By the end of 2012, the Caltech researchers say, the CMS collaboration expects to more than double its current total amount of data. With more data and analysis, the scientists might then be able to confirm whether the particle they announced is indeed the Higgs—and whether it is the Standard Model Higgs or a more exotic version.

Marcus Woo
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Caltech at the LHC

Maria Spiropulu and Harvey Newman, both professors of physics at Caltech, lead the Caltech team of 40 physicists, students, and engineers that is part of the Compact Muon Solenoid (CMS) collaboration at the Large Hadron Collider (LHC) in Geneva, Switzerland.

Spiropulu is an expert on devising ways to discover exotic phenomena beyond the Standard Model—the theory that describes how all particles interact—such as theories of supersymmetry that predict particles of dark matter. Newman did much of the design and development work on the crystal detectors that are now used in CMS. He also conceived and developed the worldwide grid of networks and data centers that stores and processes the flood of data coming from the LHC. With the LHC generating gigabytes of data per second, no single site can hold all the information, so the data is handled in a distributed fashion at hundreds of sites throughout the world, including Caltech's Center for Advanced Computing Research, the first university-based center for LHC data analysis.

Newman's team also runs the transatlantic network that links the LHC to the United States, allowing data to flow between Europe and North America. His team, together with Steven Low, professor of computer science and electrical engineering at Caltech, developed the state-of-the-art applications for transferring data over long distances, enabling terabytes of data to stream between sites at speeds of up to the 100 gigabits per second. Newman and Caltech engineer Philippe Galvez also developed a system called Enabling Virtual Organizations, an internet-based tool that helps physicists and scientists from other fields communicate and collaborate from anywhere in the world. 

According to Newman and Spiropulu, the Caltech team consists of experts in everything from the detector and data analysis to how new phenomena might manifest at the LHC. Because the group is involved in so many aspects of CMS, Caltech is making a particularly significant contribution, Spiropulu says.

"Caltech is a premier institute of technology," Newman adds. "We continue to use our skills and vision to develop and deploy unique technologies with global impact even as we empower the scientists in our field." 

The Higgs boson is predicted to decay in different ways. The Caltech team is analyzing the data from three of these so-called decay channels: the photon-photon channel, in which the Higgs decays into two photons; the ZZ channel, in which it decays into two particles called Z bosons; and the WW channel, in which the Higgs decays into two particles called W bosons.

Graduate students Yong Yang, Jan Veverka, and Vladlen Timciuc are all studying the photon-photon channel, searching for the Standard Model Higgs and excluding possible imposters. "We make sure CMS precisely measures the energies of photons, electrons, and positrons," says Adi Bornheim, a Caltech staff scientist who led the electromagnetic calorimeter (ECAL) detector group at CMS and currently participates in tests of the signal robustness at 125 gigaelectron volts (GeV, a unit of mass) in the photon-photon channel. Composed of 76,000 crystal detectors and weighing in at more than 90 tons, the calorimeter measures the energy of the electrons and photons produced by LHC collisions with high precision 

Since 1994, Newman and Ren-Yuan Zhu, Caltech's manager of ECAL—along with a team of experts on crystal calorimetry and lasers—have been making sure the detector is calibrated to provide the exquisitely precise measurements required for discovery by the CMS detector. Marat Gataullin, an assistant scientist at Caltech and leader of the calibration team at CMS, says, "It would have been impossible to find the new particle in this channel without the 17-year investment in this special detector of the Caltech CMS group."

Caltech Tolman Fellow Artur Apresyan joined the search in the photon-photon channel recently, along with graduate student Cristian Pena, who recently arrived at CERN (the European Organization for Nuclear Research, the site of the LHC) to carry out the calibration of the ECAL for the remainder of the extended 2012 run. "This is intense," Pena says. "I want to get my hands into the work and contribute immediately."

Another Caltech Tolman Fellow, Emanuele Di Marco, helped lead the analysis of Higgs decays in the WW channel for the CMS team. He will present the results on behalf of CMS at the ICHEP 2012 conference, which will be held from July 4 through 11 in Melbourne, Australia. "As the impact of the discovery sinks in, I realize how much work remains to build the full picture," Di Marco says. "Squeezing the signal out of the WW channel is challenging."   

In addition to the WW channel, Di Marco and newly arrived Caltech Millikan Fellow Si Xie have also worked on the ZZ channel. "We are doing our best to advance CMS's ability to measure this channel," Xie says. "There are already outstanding analysis techniques in CMS and we want to perfect them."

Newman, Spiropulu, Xie, Di Marco, and graduate students Chris Rogan and Yi Chen—in collaboration with colleagues from CERN, Fermilab, and Johns Hopkins University—will continue the preparatory studies for the ZZ channel; they published the first of those studies in the journal Physical Review D in 2010. They developed a kind of Higgs look-alike program that is being applied to the data to pick out the newly discovered particle.

"We will pin down the properties of this new particle," says Rogan, who was honored by Forbes Magazine as one of this year's top 30 leaders in science and technology under 30 years old. "We can learn more—we must use the knowledge from this discovery to inform and help direct our searches for supersymmetry or other exotic forms of new physics as well as experimental searches for dark matter. The implications for many other subfields are very significant." For instance, Javier Mauricio Duarte, a first year graduate student, will be using these findings in his work on supersymmetry and models of dark matter. 

As the LHC continues to ramp up its energy, physicists hope that even more discoveries are on the way. "The LHC is pretty close to my dream experiment, and the LHC at twice the energy will be even better!" said graduate student Alexander Mott in an interview with Scientific American.

Undergraduates are also a critical part of the team. In the last two years, there have been a total of 24 students from the Summer Undergraduate Research Fellowships (SURF) and Minority Undergraduate Research Fellowships (MURF) programs, as well as from programs at CERN. "Caltech students can really 'do things' from an early stage in their careers—at a level one rarely sees elsewhere," Newman says.

This summer, the group includes seven undergraduates (SURFs as well as Rose Hill and Musk Foundation summer fellows) and a couple of CERN summer students. Lisa Lee, a junior at Caltech who just arrived at CERN, sums up the experience so far with a sense of wonder. "What are the chances," she says, "that you take on a summer undergraduate research project in an experiment that makes the most significant discovery in recent history right at the moment you start?"  

Marcus Woo

X-ray Telescope Takes First Image

NASA's NuSTAR space telescope has taken its first image, snapping a shot of the high-energy X rays from a black hole in the constellation Cygnus. NuSTAR—short for Nuclear Spectroscopic Telescope Array—was launched on June 13, and is the first telescope that can focus high-energy X rays. It will explore black holes, the dense remnants of dead stars, energetic cosmic explosions, and even our very own sun.

"Today, we obtained the first-ever focused images of the high-energy X-ray universe," says Fiona Harrison, a professor of physics and astronomy at Caltech and the mission's principal investigator, in a NASA press release. "It's like putting on a new pair of glasses and seeing aspects of the world around us clearly for the first time."

Marcus Woo
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Put a Seismometer in Your Living Room

Back in the 1960s, Charlie Richter (PhD '28) installed a seismometer in his living room. It was bigger than his TV set, and it didn't go with the sofa, but it saved him a lot of late-night drives into the Seismo Lab and was a great conversation piece. Now, if you live in the Pasadena area, you can have one, too. Professor of geophysics Robert Clayton will send a wallet-sized seismometer to the first 1,000 volunteers with an Internet connection and a spare USB port. There is one small catch: you have to promise to leave your computer on 24/7.

Even as you impress your friends by creating your own mini-quakes ("we encourage people to test the unit by jumping up and down," Clayton says with a grin), you'll be contributing to a serious civic project—creating block-by-block earthquake-intensity maps that can guide ambulances and fire trucks to hard-hit areas almost while the ground is still rolling. Ordinary seismic data won't do; as we learned in the 1994 Northridge earthquake, heavy damage can strike far from the epicenter.

Crowd-sourced seismology dates to the turn of the millennium, when David Wald (PhD '93), Vincent Quitoriano (BS '99), and Humboldt State's Lori Dengler created an online questionnaire called "Did You Feel It?" The site went viral with the magnitude 7.1 Hector Mine quake, and now even a shaker in the 4 to 5 range will generate some 50,000 responses. The first thing people do—we hope!—is take cover," Clayton says. "But the second thing they do, apparently, is log on and file a report. So we want to put instruments where the people are."

A collaboration between Caltech's seismology, earthquake engineering, and computer science departments, the Community Seismic Network was inspired by what Clayton calls "the densest urban array ever"—a multimillion-dollar array of 5,206 sensors, or better than one per block, that were buried under the grassy verges between the sidewalks and the streets of Long Beach and operated from January through June of 2011. The sensors were used by the Signal Hill Petroleum Company to map its holdings by analyzing how shock waves reflected off the rock formations deep underground. The preferred oil-field survey tool is a stick of dynamite, but working in a city called for a subtler approach—sort of. "They had to pull a parade permit every day," says Clayton. A train of 30-ton vibrator trucks would drive up and down the boulevards, rattling doors and windows, preceded by a police escort to clear the way.

The survey crew worked weekdays from 9:00 to 4:00, but the seismometers ran 24/7. The array straddled the Newport-Inglewood fault zone, the source of the disastrous 1933 quake that killed 115 people. "The earth is constantly chattering away down there," says Clayton, and the network caught hundreds of after-hours tremors, including a magnitude 2.4 under nearby Carson. A color-coded video of this hiccup shows the seismic waves propagating eastward block by block, station by station. The waves distort as they encounter the fault, whose segments reveal themselves as fleeting white scars in the sea of red and blue.

The cross-sectional renderings are even more revealing. Grad student Asaf Inbal projected the waveforms from an unfelt microquake back to their source in the fault plane. The resulting animation "looks like a summer lightning storm," Clayton says, but in this case, the towering cumulonimbus clouds are actually micro-slip zones, and the thunderbolts are transitory sub-centimeter displacements striking as deep as 20 kilometers underground.

Such detailed data will allow seismologists to answer "the big question," says Clayton: "How does an earthquake nucleate? Most activity simply dies out over very small distances. What lets something suddenly take off?"

Which brings us back to Pasadena. The Southern California Seismic Network, run jointly by Caltech and the U.S. Geological Survey, runs from San Luis Obispo to the Mexican border. It includes about 40 stations in the Greater Los Angeles region, or about one every 10 kilometers; each state-of-the-art installation costs $100,000. The Community Seismic Network uses mass-produced accelerometer chips like the ones in your Wii, each costing about a hundred bucks. High-end they're not. In fact, Clayton says, "no single sensor would have impressively seen any one event. But collectively, when you have 100 of them, you see it."

Given enough sensors, you can assess seismic hazards block by block, and in some cases floor by floor. Caltech's Millikan Library, for example, has sensors on each of its nine floors, plus one on the roof and one in the basement. Undergrad Hong Sheng and senior research fellow Monica Kohler (PhD '95) used that data to create a 3-D rendering of the building's response to the magnitude-4.2 Newhall quake of September 1, 2011. Watching the library's energetic hula is rather unsettling, especially if you hang out on Millikan's middle floors; fortunately, the scale is greatly exaggerated and the actual sway is less than a tenth of a millimeter. Similar animations could alert inspectors to hidden damage after a large earthquake, Clayton says. Tall buildings sway at frequencies determined by the details of their construction, so "if this frequency drops during an event and doesn't bounce back once the shaking stops, it could be a sign of broken welds. We saw this in the Northridge earthquake."

Little by little, Clayton hopes to grow the Community Seismic Network to 15,000 sensors spanning the Los Angeles basin, from the Hollywood Hills to Lake Forest in southern Orange County. But for now he just wants to fill the area bounded by the San Gabriel Mountains and the 605, 10, and 2 freeways. Be the first one on your block—sign up today!

The Community Seismic Network is funded by the Gordon and Betty Moore Foundation and by Caltech trustee Ted Jenkins (BS '65, MS '66).

Doug Smith
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NuSTAR Space Telescope Blasts Off

Caltech-led mission will explore the X-ray universe

This morning, NASA's NuSTAR telescope was launched into the low-Earth orbit from which it will begin exploring the high-energy X-ray universe to uncover the secrets of black holes, the dense remnants of dead stars, energetic cosmic explosions, and even our very own sun.   

The space telescope—the most powerful high-energy X-ray telescope ever developed—rode toward its destination inside the nose of a Pegasus rocket strapped onto the belly of a "Stargazer" L-1011 aircraft. Around 9:00 a.m. (PDT), the plane—which had earlier taken off from the Kwajalein Atoll in the western Pacific—dropped the rocket from an altitude of 39,000 feet. The rocket was in free fall for about five seconds before the first of its three stages ignited, blasting NuSTAR into orbit around the equator.

"NuSTAR will open a whole new window on the universe by being the very first telescope to focus high-energy X rays," says Fiona Harrison, professor of physics and astronomy at Caltech and the principal investigator of the NuSTAR mission. The telescope is 100 times more sensitive than any previous high-energy X-ray telescope, and it will make images that are 10 times sharper than any that have been taken before at these energies, she says. 

NuSTAR—short for "Nuclear Spectroscopic Telescope Array"—can make sensitive observations of cosmic phenomena at higher frequencies than other X-ray telescopes now in orbit, including NASA's Chandra X-Ray Observatory and the European Space Agency's XMM-Newton observatory. X rays are at the high-frequency end of the electromagnetic spectrum, and can be thought of as light particles called photons that carry a lot of energy. Chandra and XMM-Newton can detect X rays with energies up to about 10,000 electron volts (eV); NuSTAR will be able to see photons with energies up to 78,000 eV. By comparison, the energy of visible light is just a few eVs, while the X rays used to check for broken bones have energies on the order of hundreds of thousands of eVs.

High-energy X rays can penetrate skin and muscle because they carry so much energy. But that also means that they are hard to reflect. The mirrors in optical telescopes cannot be used to reflect and focus X rays. Instead, X-ray telescopes can only reflect incoming X rays at very shallow angles. These photons travel on paths that are almost parallel to the reflective surface, like rocks skipping on a pond. To reflect enough X rays for the detectors to observe, telescopes must use nested cylindrical shells that focus the photons onto a detector. Chandra has four such nested shells; XMM-Newton has 58. NuSTAR, in contrast, has 133, providing unprecedented sensitivity and resolution.

Each of NuSTAR's nested shells is coated with about two hundred thin reflective layers, some merely a few atoms thick, composed of either high-density materials, such as tungsten and platinum, or low-density materials like silicon and carbon. By alternating the two types of layers, NuSTAR's designers have produced a crystal-like structure that reflects high-energy X rays. Harrison and her group at Caltech started developing this technology more than 15 years ago and first tested it in a balloon experiment called the High-Energy Focusing Telescope (HEFT) in 2005. 

Fiona Harrison, professor of physics and astronomy at Caltech, is the principal investigator of the NuSTAR mission.
Credit: Lance Hayashida

A telescope focuses light by bending it so that it converges onto one spot—an eyepiece or a detector. But because X rays can only be reflected at such shallow angles, they do not converge very strongly. As a result, the distance between an X-ray telescope's mirrors and the detector must be especially long for the X rays to focus. Chandra is 45 feet long and XMM-Newton is about 30 feet long—as big as buses. NuSTAR—funded under NASA's Explorers program, which emphasizes smaller, cheaper missions that do science as efficiently as possible—has a deployable mast that allows it to squeeze inside the Pegasus rocket's roughly seven-foot-long payload compartment. About a week after launch, the mast will unfold and stretch to more than 30 feet. 

This new technology, Harrison explains, "will allow NuSTAR to study some of the hottest, densest, and most energetic phenomena in the universe." Black holes are a key target of the telescope. Just 20 years ago, she says, black holes were thought to be rare and exotic, but "today we know that every galaxy has a massive black hole in its heart." Our own Milky Way galaxy, with a black hole four million times as massive as our sun, is no exception. Gas and dust block most of our view of the galactic center, but by observing in high-energy X rays, NuSTAR can peer directly into the heart of the Milky Way. 

Disks of gas and dust surround many of the supermassive black holes of other galaxies. As the material spirals into these black holes, which are millions to billions of times as massive as the sun, the regions closest to the black hole radiate prodigious amounts of high-energy X rays, which are visible even if the black hole is hidden behind dust and gas. NuSTAR will therefore allow astronomers to not only conduct a census of all the black holes in the cosmic neighborhood, but also to study the extreme environments around the black holes. Astronomers will even be able to measure how fast black holes spin, which is important for understanding how they form and their role in the history and evolution of their host galaxies. 

Astronomers will also point NuSTAR at supernovae remnants, the hot embers left over from exploded stars. After a star burns through all of its fuel, it blows up, blasting material out into space. In that explosion, new elements are formed (in fact, many of the heavier elements on Earth were forged long ago in stars and supernovae). Some newborn atoms are radioactive, and NuSTAR will be able to detect this radioactivity, allowing astronomers to probe what happens during the fiery death of a star. 

The telescope also will devote some time to the observation of our own star, the sun. The outer layer of the sun, called the corona, burns at millions of degrees. Some scientists speculate that nanoflares—smaller versions of the solar flares that occasionally erupt from the solar surface—keep the corona hot. NuSTAR may be able to see nanoflares for the first time. "In a few hours of observations, NuSTAR will answer this longstanding question that solar physicists have been scratching their heads about for years," says Daniel Stern of NASA's Jet Propulsion laboratory, NuSTAR's project scientist.

In July, NuSTAR will start taking data, revealing a whole new X-ray universe—shining, shimmering, and splendid—to scientists. "We expect amazing discoveries from it," Stern says.

The NuSTAR mission is led by Caltech and managed by JPL for NASA.

Marcus Woo
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