Transmission-Line Readout with Good Time and Space Resolutions for Planacon MCP-PMTs

With commercially-available multi-anode microchannel plate photomultiplier tubes (MCP-PMT) and electronics, resolutions significantly better than 10 psec have been achieved in small systems with a few readout channels[1,2]. For large-scale time-of-flight systems used in particle physics, which may cover tens of square meters, a solution must be found with a manageable number of electronics channels and low total power consumption on the readout electronics without degrading the system timing resolution. We present here the design of a transmission-line readout for a Photonis Planacon MCP-PMT that has these characteristics. The tube, which is 5 cm square, is characterized by signal pulse rise times in the order of 200 psec and transit time spreads (TTS) in the order of 25 psec[1, 2]. The model 85011-011 MCP has 1024 anode pads laid out in an array of 32 by 32 on the back of the tube. The proposed readout is implemented on a Rogers 4350B printed circuit board with 32 parallel 50-ohm transmission lines on 1.6 mm centers, each traversing one row of 32 pads. The board is connected with conductive epoxy to the 1024 anodes of the tube, each transmission line being read out on each end. We have simulated the electrical properties of the transmission-line readout board with Hyperlynx and Spice simulators. The simulations predict that the readout transmission-lines can achieve a signal bandwidth of 3.5 GHz, which should not significantly degrade the time and spatial resolutions intrinsic to the MCP-PMT signals.