Detector Research & Development
CCDs for Dark Energy Studies
Charge-coupled devices (CCD’s) are the imagers of choice in astronomy. The conventional thinned rear-illuminated n-channel CCD’s have limitations which are overcome by the innovative LBNL “shocking red” design. This p-channel device is made on very high resistivity silicon, and in operation the entire 200-600 um substrate is totally depleted. Because it is thick, it is uniquely sensitive to near-infrared light. Since it has no field-free region, it has the best available spatial resolution. It is up to an order of magnitude more radiation resistant than normal n-channel devices. This CCD is proposed as the SNAP optical imager, but large-format devices will also be deployed on ground-based telescopes (such as the Keck) as soon as possible. The SNAP poster image shown above was obtained with such an imager at Kitt Peak, and another has permitted the UCB et al. planet search group at Lick Observatory to significantly reduce their radial velocity errors, permitting detection of lower-mass exoplanets.
CMB Polarization Detectors
The envisioned next-generation CMB experiment, the so-called CMB S4, requires a large number of detectors (∼500,000) to achieve the necessary sensitivity. This is two orders of magnitude greater than current observing instruments, and an order of magnitude greater than new instruments under construction. A technology leap is necessary to achieve such large throughput in both fabrication and quality control. We are focused on this technology jump.
Dark Matter Detector R&D
Rare event searches requires detailed understanding of detector behavior, and as sesitivity increases, previously unobserved instrumental effects become important. The Generation 3 Dark Matter experiments will probe the tails of the distributions that were understood for G2. Our detector R&D work focuses on measuring liquid xenon signal generation, including electron extraction across liquid-gas boundary, photoelectron response of PMTs, few-keV nuclear recoil signal yields, light collection, and parasitic high voltage effects. Many LBNL facilities enable precise investigations, for example metal surface electropolishing and electron microscopy expertise and capabilities.
Integrated Carbon Composites Structures
Integrated Structures and Modular Systems is an R&D topic relevant the design and fabrication of large scale precision detectors systems, which: Have high thermal-mechanical performance, are efficient to build and install, minimize material, which is critical for collider detectors and are cost effective.
The program relies heavily on the Carbon Composites Fabrication Facility of the LBNL Engineering Division and its expert technical staff, and on collaboration with the Nuclear Science Division, Accelerator Technology, Materials Science and Molecular Foundry, Advanced Light source, and industry. A particularly important industrial partner has been Allcomp, Inc., which developed thermally conductive carbon foams with SBIR support.