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-M16-203Base from Argonne

1 pe ADC spectrum

Using amplifiers from STACEE

Photon Detection Efficiency

Courtesy of MPI Munich

Reference signal

Test signal

Diffusing Teflon

Hamamatsu R7600U-200

Photonis XP2970/02

Wash U QE measurement

Tests have shown that the G-APD can in principle be used:N. Otte and coworkers at MPI/PSI/ETH:Vienna Conference on Instrumentation 2007ICRC 2007NDIP 2008

4 MPPC-33-050C from Hamamatsu:sensor size: 3x3mm²single cell size: 50x50µm²nominal bias: 70.4Vdark rate at nominal bias: ~2MHzgain at nominal bias: 7.5*105

MAGIC Pixel Size

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

• setting up infrastructure to evaluate G-APDs- photon detection efficiency measurements- temperature chamber- …

• MPPCs ordered from Hamamatsu• in contact with several other producers

Status:

Plans:

• test available devices• R&D on G-APD pixel for a small ACT

– towards a first comprehensive field test in 2009?

we are just beginning, especially for G-APDs

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)