Experimental set-up Abstract Modeling of processes in the MCP PMT Timing and Cross-Talk Properties of BURLE Multi-Channel MCP PMTs S.Korpar a,b, R.Dolenec b, P.Križan c,a, R.Pestotnik b, A.Stanovnik c,a a University of Maribor, Slovenia, b Jožef Stefan Institute, Ljubljana, Slovenia, c University of Ljubljana, Slovenia, Uniformity of response For the Belle particle identification system upgrade, a proximity focusing RICH detector with aerogel as radiator is being considered. One of candidates for the detector of Cherenkov photons is a microchannel plate PMT. With its excellent timing properties, such a counter could serve in addition as a time-of-flight counter. A prototype of this novel device using BURLE anode, microchannel plate PMT, was tested in the test beam at KEK. Excellent performance of this counter could be demonstrated (left). In particular, a good separation of pions and protons was observed in the test beam data with a time-of-flight resolution of 35ps (right). Motivation We report on on-the-bench studies of the two types of BURLE multi anode micro- channel plate (MCP) PMTs, one with 64 channels and 25um pores and the other with 4 channels and 10um pores. A possible applications of this tubes are RICH and time- of-flight counters. We have investigated the timing properties of the tubes and studied various cross-talks and their influence on the timing and spatial resolution. Present study: -measure detailed timing properties and cross-talk, -determine their influence on the position resolution and time resolution. BURLE MCP-PMT: - multi-anode PMT with two MCP steps - 2x2(8x8) anode pads - 10(25) mm pores - bialkali photocathode - gain ~ 0.6 x collection efficiency ~ 60% - box dimensions ~ 71mm square Outside dark box: - PiLas diode laser system EIG1000D (ALS) nm and 635 nm laser heads (ALS) - neutral density filters (0.3%, 12.5%, 25%) - optical fiber coupler (focusing) - optical fiber (single mode,~4mm core) Signal processing: - laser rate 2kHz (~DAQ rate) - amplifier: 350MHz (<1ns rise time) - discriminator: leading edge, 300MHz - TDC: 25ps LSB(s~11ps) - QDC: dual range 800pC, 200pC - HV 2400V Inside dark box mounted on 3D stage: - optical fiber coupler (expanding) - semitransparent plate - reference PMT (Hamamatsu H5783P) - focusing lens (spot size s ~ 10mm) TDC vs. ADC correlation is fitted with and used for TDC correction ADC raw TDC Time walk correction Comparison of the charge sharing effects for red (635 nm) and blue (405 nm) laser. red blue red = range of back-scattered photo-electrons 2 x 12mm Surface response of PMTs is fairly uniform. Multiple counting is observed at pad boundaries due to charge sharing. Photo-electron: d 0,max ~0.8 mm t 0 ~ 1.4 ns Δt 0 ~ 100 ps  Parameters used: - cathode to MCP potential difference U = 200 V - photocathode to MCP distance L = 6 mm - photoelectron initial energy E 0 = 1 eV Uniformity of timing Charge sharing Distributions assuming that back- scattering by angle  is uniform over the solid angle. ~ 2.8ns ~ 12mm  = 40ps  = 37ps  = 38ps  = 39ps 70% 20% 10% Time resolution of the main peak is dominated by the photo-electron time spread ( 26ps rms, estimated from the model); other contributions are laser timing (15ps rms) and electronics (12ps rms). TDC distribution has three contributions: - prompt signal ~ 70% - short delay ~ 20% - uniform distribution ~ 10% back-scattering Timing Backscattering: d 1,max =2L=12 mm t 1,max ~ 2.8 ns Charge sharing    Slice of 2D distribution shows uniform response within the pads, short range cross-talk due to charge sharing and long range photoelectron backscattering cross-talk. Distributions of hits with equal signals on both pads for the red and blue lasers. The distribution is broadened for the blue light due to larger initial photoelectron energy. 2x2 channel tube 8x8 channel tube Time-walk corrected TDC distributions of all four channels of 2x2 MCP PMT. amplifier ORTEC FTA820A signal splitter passive 3-way discriminator Philips model 806 QDC CAEN V965 VME TDC Kaizu works KC3781A CAMAC NIM PC LabWindows CVI ALS PiLas controller Fraction of the signal measured on the left pad vs. light spot position while scanning over pad boundary using red and blue lasers. Photo-electron range, projected Photo-electron travel time