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Photosensor Work at UCSC. Concentrate on technologies that are: Newer than conventional PMT Now or soon in commercial production Multianode & high QE PMT Develop test infrastructure (also for G-APDs) Some initial tests Geiger-APD Otte brings expertise & ideas from his PhD work
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Photosensor Work at UCSC • Concentrate on technologies that are: • Newer than conventional PMT • Now or soon in commercial production • Multianode & high QE PMT • Develop test infrastructure (also for G-APDs) • Some initial tests • Geiger-APD • Otte brings expertise & ideas from his PhD work • No financial support • Borrowed & scavenged equipment • Free undergraduate labor
MAPMT Tests Hamamatsu R8900-M16-203 Base from Argonne 1 pe ADC spectrum Using amplifiers from STACEE
Photon Detection Efficiency Diffusing Teflon Hamamatsu R7600U-200 Reference signal Photonis XP2970/02 Wash U QE measurement Courtesy of MPI Munich Test signal
Tests have shown that the G-APD can in principle be used: N. Otte and coworkers at MPI/PSI/ETH: Vienna Conference on Instrumentation 2007 ICRC 2007 NDIP 2008 MAGIC Pixel Size 4 MPPC-33-050C from Hamamatsu: sensor size: 3x3mm² single cell size: 50x50µm² nominal bias: 70.4V dark rate at nominal bias: ~2MHz gain at nominal bias: 7.5*105 • the devil is in the detail: • can costs be sufficiently reduced that the G-APD becomes competitive to the PMT? • optical crosstalk could limit low energy performance on trigger level • is temperature dependence an issue? • how severe are parameter fluctuations from device to device • … Extensive R&D program ahead that has to figure out if the G-APD can be used to meet our physics goals
Status and Plans at UCSC Status: • setting up infrastructure to evaluate G-APDs • photon detection efficiency measurements • temperature chamber • … • MPPCs ordered from Hamamatsu • in contact with several other producers we are just beginning, especially for G-APDs Plans: • test available devices • R&D on G-APD pixel for a small ACT • towards a first comprehensive field test in 2009? AGIS R & D Proposal: • design of prototype camera(s), including choice of sensor(s) • how sensor features impact trigger performance • procure and test sensors for prototype camera(s)