Three SLAC Scientists Receive DOE Early Career Research Grants

Three scientists at the Department of Energy’s SLAC National Accelerator Laboratory will receive DOE Early Career Research Program grants for research to find evidence of cosmic inflation, understand how plasmas excite particles to high energies and develop a way to accelerate particles in much shorter distances with terahertz radiation.

Zeeshan Ahmed, Frederico Fiuza and Emilio Nanni were among 59 scientists selected out of about 700 applicants for the grants, which were announced August 9. They will receive about $500,000 per year for five years for salary and research expenses. You can see brief descriptions of the award winners’ work here.

The grants support the development of individual research programs of scientists who received their doctoral degrees up to 10 years earlier. Recipients must be full-time DOE national laboratory employees or tenure-track assistant or associate professors at a U.S. academic institution, and their research topics must fall within one of six Office of Science focus areas.

Zeeshan Ahmed: More Firepower on the CMB Sky

Ahmed, a project scientist and Panofsky Fellow at the Kavli Institute for Particle Astrophysics and Cosmology at SLAC, led the design, testing, construction and deployment of the SLAC and Stanford BICEP3 telescope at the South Pole in 2015 as a postdoctoral scholar on Chao-Lin Kuo's observational cosmic microwave background (CMB) research team at Stanford. 

BICEP3 belongs to the third generation of instruments scientists are using to look for patterns in the CMB as evidence of cosmic inflation – the rapid expansion of the early universe following the Big Bang.  

“We invented that quantum leap from the second to third generation of BICEP telescopes, and a lot of the technology that went into it was developed at SLAC,” Ahmed says. “BICEP3 has been taking high-quality data and the highest throughput of data of this kind for the past two years. In a year or two, the data collected with BICEP3 will produce deep maps that surpass the sensitivity of all previous CMB maps for inflation science.”

Prior to joining Stanford, Ahmed conducted graduate research on the second-generation Cryogenic Dark Matter Search, CDMS-II, leading the primary analysis of the final dataset. Ahmed received his PhD in physics from California Institute of Technology in 2012.

The Early Career grant will support his work on a fourth-generation technology for CMB cameras that can map a much larger part of the sky – 40 percent instead of the current 1 percent – at close to the same depth that BICEP3 will achieve at the end of its science program.

Whereas BICEP3 technology widened camera apertures, the fourth generation will focus on building larger arrays of camera sensors using scalable signal transduction techniques.

“If you think of a sensor as a unit of sensitivity, or firepower on the sky, we want to go an order of magnitude beyond the firepower we currently have – from tens of thousands of sensors to hundreds of thousands of sensors,” Ahmed says. “This would allow us to cover a large part of the sky very deeply and make maps that are useful for many scientifically compelling problems, such as inflation, measuring neutrino mass, finding relic particles that haven’t been detected yet, better understanding dark energy and large-scale structure, and more.”

To do so, Ahmed is working closely with SLAC and Stanford professor Kent Irwin’s groups in SLAC’s Technology Innovation and Particle Astrophysics directorates to explore questions such as how to get information out of the sensors more efficiently and how to package them better.

“It’s absolutely gratifying to receive this award,” he says. “It’s extremely competitive, but I think we do have a very compelling research case, and I’m glad the DOE supports this work as one of the directions to pursue for the next-generation CMB experiment.”

“Zeeshan has made tremendous contributions to BICEP3, the most sensitive B-mode machine operating at the frequency that has the best chance to see a signal,” Kuo says. “He is now on a great trajectory, aiming to bring all the pieces together to make the next-generation CMB focal planes. It is gratifying for me to see this recognition for him.”

Irwin adds, “Zeeshan is playing an invaluable leadership role in planning and executing SLAC’s plan for participation in CMB-S4. This includes planning pre-project R&D and preparing for project execution.

“One important area of scientific work for him has been in the development of next-generation readout electronics for CMB detectors, including CMB-S4, the BICEP series and Simons Observatory. His leadership in this area has been invaluable in coordinating electronics development, cryogenics testing and scientific implementation. This recognition for Zeeshan is exciting and very appropriate!”

Frederico Fiuza: Simulating ‘A Sea of Charged Particles’

Fiuza creates numerical experiments in plasma physics as a staff scientist and leader of the theory group in the lab’s High Energy Density Science division.

In this role, he models processes in plasma, or ionized gas, that accelerate particles to high energies. The work has a wide range of applications, from illuminating astrophysical phenomena to exploring controlled fusion energy and shrinking particle accelerators for medical therapy.

“In addition to using simulations, I like to work very closely with experimental teams and design laboratory experiments where these models can be verified and we can test our predictions,” Fiuza says. “Basically, we use high-power lasers to heat matter to high energies, dissociate the electrons from the atoms and explore the physics of the resulting sea of charged particles.”

The simulations he builds capture the fundamental physics of plasmas at small scales. The very small-scale physics is particularly demanding to model, Fiuza says, and there’s still quite a bit researchers don’t understand.

“There are a lot of directions one can explore,” Fiuza says. “Plasmas can support electric fields much stronger than those in conventional accelerators, which are limited by the breakdown of materials. Because plasma is already broken down into electrons and ions, we can achieve much higher electric fields, but we need to control them in a way that produces particle beams with very precise characteristics.”

Fiuza was introduced to plasma physics in a computational physics course as an undergraduate student. For the final project, the professor asked him to model a “surfatron” – an idea for accelerating particles to high energies as if they were surfers riding plasma waves.

“I was surfing quite a bit at the time, so it was all really exciting to me,” Fiuza says. “That really got plasmas in my head and I wanted to know more about it.”

That same professor—Luis Silva— became Fiuza’s PhD advisor. Fiuza earned his doctoral degree in plasma physics from Instituto Superior Tecnico in Lisbon, Portugal. In 2009, he was a visiting scholar in the Plasma Simulation Group at the University of California Los Angeles. From there he went to Lawrence Livermore National Laboratory as a Lawrence Fellow, and came to SLAC in 2015.

He will use the early career award for research aimed at understanding exactly how plasmas lead to efficient particle acceleration. Fiuza will work with researchers to propose and design laser experiments that test these models.

“This award means that for the next five years, I know that I will have the support to carry out the research that I’m really excited about and will have a team that can work with me on these goals,” Fiuza says.

Siegfried Glenzer, director of the High Energy Density Science Division, says, “Frederico’s work is world-leading. His insights into plasma physics and how particle acceleration works have greatly influenced the way we do laser experiments in pursuit of grand-challenge goals. His simulations have shown us how we can determine the physics important for the origin of cosmic rays. This award will allow him to significantly advance the field.”

Emilio Nanni: Exploring a Technological Desert

Nanni is an associate staff scientist in the lab’s Technology Innovation Directorate (TID), where he is working on ways to accelerate electrons to high energies in much shorter distances than possible today.  This particular approach uses terahertz radiation – a wavelength that falls between visible light and radio waves – to accelerate electrons through finely milled metal structures; a dozen of the experimental prototypes fit in your hand. But there are a number of challenges to overcome before the technology can be scaled up to high energies and leave the lab bench for deployment in the wider world.

“We’re trying to shrink the size of accelerators for a whole host of applications, from experiments in high-energy physics, biology and chemistry to new tools for medical treatment,” Nanni says.

“Terahertz radiation is at a sweet spot, where its wavelength is short enough to potentially achieve high gradients – high rates of acceleration in a short distance – at a frequency where metal structures are highly conductive. It can also offer very high pulse rates. That’s especially important to SLAC because we would like to be able to use it in experiments at the lab’s Linac Coherent Light Source X-ray free-electron laser.” LCLS is a DOE Office of Science User Facility.

Nanni came to SLAC in 2015 from MIT, where he earned his PhD and did postdoctoral research on generating terahertz waves and using them to accelerate electrons, among other things. By the time he arrived, he had already applied for and won a SLAC Laboratory Directed Research and Development grant to develop a way to use a laser system to generate very intense terahertz pulses.

The Early Career grant will help him “lay the foundation for terahertz accelerator technology,” according to a description of his work posted by DOE.

“I was blown away,” Nanni says of the award. “It’s such a unique opportunity to pursue what you’re passionate about and chart your own course, and it’s a big recognition of the people who have supported you along the way. Science is a team effort, and having good people around you helps you refine your thoughts and pursue valuable goals that are challenging.”

Michael Fazio, associate lab director in charge of TID, says, “This is very groundbreaking work. There is a big gap between the frequencies at which we operate accelerators today and some of the really far-out work being done with laser-driven acceleration. That gap is a technological desert, and Emilio has some very good ideas about how to exploit it. His work is very connected to what we do and to what the DOE is interested in.”

Craig Burkhart, head of TID’s RF Accelerator Research Division, adds, “Emilio arrived here with a well-formulated vision for a research program, and this Early Career Award will give him the opportunity to explore that. It’s a rare opportunity, and one that he richly deserves.”

For questions or comments, contact the SLAC Office of Communications at communications@slac.stanford.edu.

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, Calif., SLAC is operated by Stanford University for the U.S. Department of Energy's Office of Science.

SLAC National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The 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.