T. Held, M. Albrecht, T. Erlen, M. Fink, F.H. Heinsius, C. Motzko, P. Musiol, C. Schnier, M. Steinke, H.-C. Wenzel, U. Wiedner,
An LED/LCD-based monitoring system for the PANDA Electromagnetic Calorimeter
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,
The light pulser monitoring system is described in the thesis of Christof Motzko, Ruhr-Universität Bochum, April 2012 (in German)
More up to date information can be found in the thesis of Patrick Musiol, Ruhr-Universität Bochum, June 2018 (in German)
The optical fibers will be Silica / Silica fibers with a Polyimid jacket and a numerical aperture of 0.28. For every crystal 4 optical fibers with a core diameter of 200 µm will be mounted close to each over.
The light pulser monitoring system has to provide the following functions
- Monitoring of the photodetector-electronics gain at a precision of 0.1% repeated at the order of minutes. The absolute stability has to be at least 0.1 % at the order of days.
- Monitoring of the radiation damage of the crystals by comparing the output of the red/green LEDs with the blue LED. Repeated at the order of minutes, possibly within the cycle.
- Monitoring of the linearity of the electronics: Repeated about every hour during cycle break. Precision about 10% of the resolution.
Energy resolution and corresponding number of pulses:
Beam structure and time for light pulses
- Every 1.8 µs a 400ns break (bucket barrier cavity) -> time for gain checks (not at maximum energy to avoid pileup!)
- Per cycle o(hour) about 1000s accumulation -> time for linearity checks
Number of light pulser = 44
- 2 backward EMC
- 32 barrel EMC
- 10 forward EMC
Light pulser properties
- 23 Oct 2009
- 11 Mar 2021