Measured baseline fluctuations and dark counts with BurlePhotonis
Measured baseline fluctuations and dark counts with Burle-Photonis MCP-PMT's Jean-Francois Genat and Edward May Dec 2009 –Jan 2010
Experimental conditions 10 and 25 mm 2” x 2” Burle-Photonis MCP tested - 25 mm MCP HV: 1. 7 -2. 0 k. V Signals taken on one anode pad and fours neighbors grounded: - 10 mm MCP HV: 2. 2 -2. 5 k. V Signals taken on one anode pad and fours neighbors grounded: Use Ed’s calibrated test setup 408 nm light set at 100 Photo-Electrons TDS 6154 C 18 GHz abw from Tek
408 nm laser 100 Photo-Electrons Signals Conclusions: Gain is 40 m. V/100= 0. 4 m. V/PE (25 mm) at 2100 V 5 m. V/100= 50 m. V/PE (10 mm) at 2500 V 10 mm somewhat faster rise time, longer trailing edge, presumably due to 4 pads connected together. The rise time does NOT depend upon the amplitude
Signals spectrum Fourier spectrum of a 2”x 2” MCP signal System noise 2 GHz Slope as steep as possible 4
Baseline dark noise vs HV Conclusion: Baseline at 675 m. V , no dependence with HV
Impulse dark noise vs HV Conclusion: At full efficiency (25 mm 2000 V, 10 mm 2400 V), dark counts rates are: 25 Hz (25 mm) 20 Hz (10 mm)
Conclusions MCP PMTs show signals, baseline fluctuations and dark counts quite similar to regular Photomultiplier tubes With: Faster signals (device is thinner, consequently better timing resolution) rise-time 250 -500 ps rise time compared to 500 ps-1 ns Less noise compared to “good” PM Tubes: dark counts 10 -100 compared to 100 -1000 Hz The rise time does NOT depend upon the amplitude
- Slides: 7