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properties of photomultiplier Hamatsu R7725 at room temperature

properties of photomultiplier Hamatsu R7725 at room temperature. Hans-Otto Meyer, 2/14/07. photomultipliers. I tested five Hamamatsu R7725 photomultipliers. measurements. LED pulser 467 nm f = 9835 Hz. PS777 amp. LRS 621 Discr, U D. LRS 4300 FERA ADC. Wiener USB crate contr.

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properties of photomultiplier Hamatsu R7725 at room temperature

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  1. properties of photomultiplierHamatsu R7725at room temperature Hans-Otto Meyer, 2/14/07

  2. photomultipliers I tested five Hamamatsu R7725 photomultipliers

  3. measurements LED pulser 467 nm f = 9835 Hz PS777 amp LRS 621 Discr, UD LRS 4300 FERA ADC Wiener USB crate contr. LRS 2277 TDC UHV 7.05 mm dia. aperture R7725 30 cm stops common start UL trigger measured (for every light pulse delivered to photocathode: ● amplitude of anode output ● times (after light pulse) of up to 16 pulses within a T = 16.4 μs period (discriminator set below 1pe response) UHV set to make 1pe pulse height similar for different tubes Variable-amplitude LED pulser, every light pulse makes a trigger for each PM, took data with four different light levels, including no light at all

  4. ΔE amplitude spectrum #3378 UHV = 1800 V UL = 10.03 V λe = 2.03 2/9/07 example deduced: ● N0 total number of events (light flashes) ● λe avg. number of photoelectrons emitted from cathode (from a fit with sum of Gaussians, red line) ● ε relative quantum efficiency (λe for constant light intensity, arbitrarily normalized) ● ΔE/E (in %) energy resolution of tube

  5. example: #3378 UHV = 1800 V UL = 10.03 V λe = 2.03 2/9/07 after-pulses dark current initial event time distribution time after light flash (μs) deduced: ● ndarkrate of dark events (no light) ● q ≡ Ndark/N0/λe the probability to have an after-pulse after an event that makes an avg. of 1 photoelectron (verified that number of dark-pulses scales with avg. number of pe’s)

  6. time distributions vary ‘normal’ tubes (3378, 3379) (distributions are similar) time after light flash (μs) modified tubes (3692, 3693, 3694) (distributions are similar) initial pulse time after light flash (μs)

  7. summary Hamamatsu R7725

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