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From the Director of Particle Physics and Astrophysics: Future Directions in Non-Accelerator Physics

(Photo - David MaFarlane)

Defining a field by what it is not might seem like an odd approach. However, as the name implies, the Department of Energy Non-Accelerator Program encompasses the broad array of science pursued with experiments and facilities other than those at accelerators. Many of the most compelling questions in particle physics and cosmology are being addressed at experiments deep underground, on mountain tops and even in space. What is the nature of dark energy? Can we directly detect evidence for primordial dark matter particles from the early universe? Is there evidence for dark matter in the high-energy gamma-ray universe? Is the neutrino its own anti-particle? Can we find evidence for the physics behind inflation? Answering these questions has taken high-energy physics a long way away from the traditional accelerator-based experiments.

Over the past decade or more, SLAC has been developing a growing effort in non-accelerator physics, particularly following the creation of the Kavli Institute for Particle Astrophysics and Cosmology in 2002. The foundation of this program is presently the Fermi Gamma-ray Space Telescope, exploring the high-energy gamma-ray universe with exquisite sensitivity. The Enriched Xenon Observatory is in the midst of commissioning the experiment and at the beginning of a planned a five-year search for neutrinoless double beta decay as a probe of the nature of the neutrino. SLAC is engaged with Fermilab and the Super Cryogenic Dark Matter Search Collaboration in planning for the next-generation dark matter experiment.

A cornerstone for the future SLAC non-accelerator program will be the Large Synoptic Survey Telescope, or LSST, a wide-field-of-view survey telescope designated as the top priority ground-based project by the recent decadal survey in Astronomy and Astrophysics. SLAC is the lead laboratory for the DOE contribution to the project, which is primarily centered on the 3.2 Gigapixel, 0.65 meter diameter digital camera. The camera employs many of the techniques found in vertex detectors for particle physics experiments, making the technical role a good match to core capabilities within the DOE high-energy physics community. Data management and exploitation of the anticipated 30 petabyte dataset will be a major challenge, one with plenty of directly relevant experience within the HEP community. National Science Foundation Astronomy and the DOE are taking initial steps to obtain approval for the LSST project, with a nominal construction start in fiscal year 2014 and first light in 2020. By providing a variety of yardsticks to measure the time evolution of the expansion rate of the universe, LSST will take a giant step closer to understanding the nature of dark energy.

Last month the Office of High Energy Physics conducted a comparative review of the existing and proposed non-accelerator research programs at Argonne, Brookhaven, Fermi, Berkeley and SLAC national laboratories. While the final report is still in preparation, the reviewers were overall very impressed with the strength of the program. They were particularly complimentary about the Fermi telescope program, acknowledging SLAC’s leading role in high-energy gamma-ray physics both now and potentially in the future with a proposed ground-based Cherenkov Telescope Array. LSST was seen as the flagship experiment of the high-energy physics effort at SLAC going forward, an effort the reviewers saw as well led by the laboratory. Our entry into SuperCDMS was seen very favorably, with encouragement to do even more in the arena of direct dark matter detection. The reviewers also had thoughtful advice for the overall DOE program.

The future for non-accelerator physics looks exciting at SLAC and elsewhere in the DOE complex. Now if we could only find a better name, one that doesn’t define the science opportunities and techniques by what they are not!

—David MacFarlane
  SLAC Today, November 19, 2010