Professor Blas Cabrera Elected to National Academy of Sciences

Blas Cabrera. (Credit: Stanford University.)

Blas Cabrera, the Stanley G. Wojcicki Professor in physics at Stanford University and 2020 member of NAS, searches for dark matter—the mysterious, unseen substance that makes up a quarter of the mass/energy budget in the Universe, weaving a cosmic web within which normal matter has collapsed into the galaxies we see today. He is a long-time leader of the Cryogenic Dark Matter Search (CDMS), for which he shared (with Berkeley's Bernard Sadoulet) the 2013 W.K.H. Panofsky Prize in Experimental Particle Physics from the American Physical Society.

Cabrera helped guide the experiment through 30 years and five increasingly powerful and innovative iterations that pushed the search for WIMPS (Weakly Interacting Massive Particles, a theorized form of dark matter) to higher and higher levels of sensitivity. The experiment began as CDMS at an underground site at Stanford University, where it ran through the 1990s and into the early 2000s. Subsequent interations CDMS II and SuperCDMS Soudan moved to the Soudan Underground Laboratory, located in an old Minnesota iron mine, which provided shielding against other types of particles that could trigger falsely postive results. Also in Soudan, the CDMSlite experiment adapted existing SuperCDMS detectors to search for low-mass WIMPs.

After serving as spokesperson for SuperCDMS Soudan, Cabrera served as project director for the latest incarnation of the project: SuperCDMS SNOLAB, which gets its name from the SNOLAB facility where it is currently (as of 2020) being installed. SNOLAB is in an active mine in Sudbury, Canada, using a larger array of more sensitive detectors placed at a depth of about 6,800 feet—compared to about 2,600 feet for the experiments at the Soudan Mine—with a corresponding increase in shielding. The project searches for low-mass WIMPs and the cryostat facility will support future upgrades.

The CDMS experiments use novel cryogenic detectors made from the semiconductors germanium and silicon, operated below 0.1 K. The technique of using superconducting tungsten to detect thermal signals from semiconducting crystals interacting with weakly interacting particle like WIMPs or neutrinos was proposed in 1985 by Cabrera, Lawrence M. Krauss, and Frank Wilczek. In addition, in 1995 Cabrera and his then-graduate student (now KIPAC colleague) Kent Irwin developed the superconducting transition edge sensor technology which provides the best energy resolution developed to date for particle detection experiments such as X-ray spectroscopy and dark matter searches.

The NAS is a private, nonprofit institution created in 1863 to advise the nation on issues related to science and technology. Members are elected in recognition of their significant contributions to research. 

For more information on Stanford NAS inductees, see Nine Stanford faculty elected to National Academy of Sciences.