Beam test of a Time-of-Flight detector prototype

Abstract

-We report on results of a Time-of-Flight, TOF, counter prototype in beam tests at SLAC and Fermilab. Using two identical 64-pixel Photonis Microchannel Plate Photomultipliers, MCP-PMTs, to provide start and stop signals, each having a 1 cm-long quartz Cherenkov radiator, we have achieved a timing resolution of σ Single_detector ~14 ps.

High resolution photon timing with MCP-PMTs: A comparison of a commercial constant fraction discriminator (CFD) with the ASIC-based waveform digitizers TARGET and WaveCatcher

“…This detector setup was used for the timing measurement reported in this paper and is the same as used in a Fermilab beam test [1]. In the test beam we used a 1cm-thick quartz radiator with Al-coated cylindrical sides, which yields a number of photoelectrons, Npe ~35±5, producing a total charge of Ntotal > 6-8x10 5 avalanche electrons, which is the necessary minimum to obtain good timing resolution.…”

“…In the test beam we used a 1cm-thick quartz radiator with Al-coated cylindrical sides, which yields a number of photoelectrons, Npe ~35±5, producing a total charge of Ntotal > 6-8x10 5 avalanche electrons, which is the necessary minimum to obtain good timing resolution. 1 In order to permit safe operation of the MCP by mitigating aging effects in a high rate environment, one wants to keep the total avalanche charge as low as possible. At the same time, the signal amplitude must still be sufficient to obtain good timing resolution.…”

“…At the same time, the signal amplitude must still be sufficient to obtain good timing resolution. A quartz radiator produces a prompt 1 Expected timing resolution with a threshold type of electronics is: σt = σnoise/(dS/dt)thresh ~ tr/(S/N), where σnoise is the rms noise, (dS/dt)thresh is the derivative of signal evaluated at the threshold, tr is the pulse rise-time and S/N is the signal-to-noise ratio.. Therefore the rise-time tr and S/N are crucial variables to realize good timing resolution.…”

“…The traditional method is to use constant-fraction-discriminators (CFDs), coupled to high resolution Time to Digital Converters (TDCs), and Analog to Digital Converters (ADCs) to correct residual amplitude-dependent timing shifts ("time walk"), which the CFD does not entirely remove [1]. Using this standard technique we have achieved a timing resolution of σ 14ps per counter in both test beam and laser bench tests [1] (see also Fig.2).…”

“…The traditional method is to use constant-fraction-discriminators (CFDs), coupled to high resolution Time to Digital Converters (TDCs), and Analog to Digital Converters (ADCs) to correct residual amplitude-dependent timing shifts ("time walk"), which the CFD does not entirely remove [1]. Using this standard technique we have achieved a timing resolution of σ 14ps per counter in both test beam and laser bench tests [1] (see also Fig.2). The MCP-PMTs were operated at a low gain of 2-3x10 4 in these tests, as the aim was not to be sensitive to single photons, which are a dominant background in high luminosity e -e + collider detectors, ideally making the detectors sensitive only to charged particle tracks.…”