Avalanche photodiode detector for high dynamic range point counting and timing experiments
Many experiments still use NaI-phototube detectors for point-counting situations. These have a count-rate limit of around 100KHz.
It is therefore frequently necessary to attenuate beams in order to bring the count rate into the linear range of such a detector.
Integrating detectors have significant disadvantages and a serious noise penalty at low rates.
Avalanche photodiodes have become quite reliable, and have capabilities above 107 Hz, with similar energy discrimination to NaI.
Fast rise time ~700 pSec., timing resolution of better than 100 pSec. is achievable.
This data was collected without any attenuators.
Maximum rate is limited by NSLS 54MHz bunch rate.
VUV ring bunch structure
Auto correlation of APD signal using CFD and TAC.
Timing resolution of 70 pSec. FWHM is shown.
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