Abstract
A subset of the ∼1000 CMS hybrid photodiode tubes which passed through our quality assurance program was subjected to long term testing of their properties as a function of time. Over the course of several years, the tubes were operated under non-uniform illumination at rates up to 3.75 nW per pixel and for total integrated charges of up to 7 C at the anode. In situ measurements of quantum efficiency and gain, coupled with periodic photocathode uniformity scans, dark current and cross talk, provide information on expected time-dependent changes in the tube photosensitivity and some indication of possible failure modes.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 250-258 |
| Number of pages | 9 |
| Journal | Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment |
| Volume | 587 |
| Issue number | 2-3 |
| DOIs | |
| State | Published - Mar 21 2008 |
Bibliographical note
Funding Information:The studies done here represent long term tests done on selected HPDs, while those that passed quality assurance were being installed and tested at FNAL and CERN. We wish to acknowledge A. Heering and N. Pearson who set up much of the original quality assurance stations at Minnesota, some of which were used in these studies. We thank our HCAL collaborators A. Ronzhin, S. Los, J. Freeman, J.E. Elias, and D. Persyk for fruitful discussions and earlier characterization studies. This work was supported by the Department of Energy under Grant DE-FG02-94ER40823 and HCAL project funds managed by FNAL.
Keywords
- CMS HCAL
- HPD
- Hadronic calorimeter
- Hybrid photodiode