New Detectors Unravel Cosmology

Cynthia Hunt
California Institute of Technology
Materials Science Department
Observational Cosmology Group

A fossil record of the universe exists just after the Big Bang, long before the formation of the first galaxy or star. This primordial radiation is imprinted on the sky as the cosmic microwave background, or CMB.  Cosmologists measure the temperature fluctuations of the CMB to understand among other things, the geometry, baryonic density, and isotropy of the universe. After the discovery of the CMB by Penzias and Wilson in 1965, almost 25 years passed before detector technology was mature enough to detect these temperature fluctuations.  It was another 10 years before the detectors were sensitive enough to make a map of the anisotropy with a single detector. The next big challenge for observational cosmology is to measure the polarization of the CMB, which can provide direct proof of the inflationary epoch and even detect signatures of gravitational waves. The curl-polarization in particular requires a large advance in the format of millimeter-wave detector arrays. SAMBA (Superconducting Antenna-coupled Multi-frequency Bolometric Array) is being developed to address these needs for the next generation of sub-millimeter astronomical detectors. SAMB  consists of a focal plane populated with microstrip antennas, whose signals are coherently added and sent to transition edge superconducting bolometers (TES) via microstrip lines. As a precursor to a full monolithic high-density antenna array, we are developing a single band antenna-coupled bolometric detector. The fabrication and testing of these proof-of-science devices will be
discussed, as well as an overview of the science of the CMB.