Cosmic Axion Spin Precession Experiment (CASPEr)

  • Awardees
  • Surjeet Rajendran, Ph.D. University of California, Berkeley
  • Dmitry Budker, Ph.D. Helmholtz Institute
  • Peter Graham, Ph.D. Stanford University
  • Alex Sushkov, Ph.D. Boston University
Year Awarded


The nature of dark-matter is one of the most fundamental open problems in physics, since dark matter constitutes over 85 percent of the total matter in the Universe. The particles comprising dark matter are likely to experience non-gravitational interactions; observing such interactions would uncover new laws of nature and reveal the origins of the dominant source of matter in the cosmos. Ultralight bosons, such as axions and axion-like particles, are prime dark-matter candidates. Axionic dark matter can cause nuclear spins to precess at a frequency set by the mass of the dark matter. The Cosmic Axion Spin Precession Experiment (CASPEr) aims to use nuclear magnetic resonance (NMR) techniques for detecting this spin precession. A signal in these experiments can be unambiguously verified using several detectors, since the frequency of the dark-matter signal is independent of the experimental setup. This novel approach should be able to detect light mass axions; a dark matter candidate that is strongly motivated from theoretical considerations. A detection in such an experiment would not only be the discovery of dark matter but would also provide insights into the high-energy scales from which the axion arises, near the fundamental scales of particle physics, such as the scale of grand unification and the Planck scale.

Surjeet Rajendran graduated from the California Institute of Technology in 2004 with a degree in mathematics and subsequently pursued a Ph.D. in physics from Stanford University, graduating in 2009. He was the Leon Madansky postdoctoral fellow at Johns Hopkins University and is presently the Henry Shenker Professor of Physics. He joined the University of California, Berkeley Physics Department in July 2014.

Dmitry Budker received his Ph.D. in physics from University of California, Berkeley, in 1993 and was a postdoctoral researcher at the university until his faculty appointment in 1995. Born in the former USSR, Budker was a student at the Novosibirsk State University from 1980 until 1985, when he received an equivalent to MS with honors from the Department of Physics. He then served as a junior researcher at the Institute of Nuclear Physics, where he conducted research on laser spectroscopy of atoms. In 1994, Budker received the American Physical Society Award for Outstanding Doctoral Thesis Research in Atomic, Molecular, and Optical Physics. He is a recipient of the NSF CAREER award, a Fellow of the American Physical Society (APS) and served as the Chair of the APS Topical Group on Precision Measurements and Fundamental Constants 2014 – 2015.  He was a Miller Professor 2003 – 2004 and 2012 – 2013. Since 2014, Dmitry Budker has led the Matter-Antimatter Asymmetry section of the Helmholtz Institute in Mainz, Germany.

Peter Graham is interested in discovering the fundamental laws of nature that lie beyond the known standard model. He received an A.B./A.M. from Harvard University in 2002 and a Ph.D. from Stanford University in 2007. He has been an assistant professor in the Stanford Institute for Theoretical Physics since 2010. He received a DOE Early Career Award in 2014 for his work on dark matter.

Alex Sushkov is currently an assistant professor at Boston University, employing magnetic resonance tools to search for axion-like dark matter and using NV centers in diamond for nanoscale magnetic studies of materials and spin systems. He is the author of over 30 research articles and a co-author of the book Physics on Your Feet: Berkeley Graduate Exam Questions. He received his Ph.D. from the University of California, Berkeley, where he developed methods for atomic magnetometry with room-temperature alkali-vapor cells, and in cryogenic buffer-gas cells, in addition to being an active member of the ORNL neutron EDM collaboration, performing measurements of the electro-optical Kerr constant of superfuid liquid helium. He then had positions at Yale and Harvard Universities, where he continued work on precision experiments studying fundamental physics.

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