Single Photoelectron Timing Resolution Research Articles

Timing resolution and rate capability of Photonis miniPlanacon XPM85212/A1-S MCP-PMT

We report here on a set of experiments that focus on measuring the timing performance of the Photonis miniPlanacon XPM85212/A1-S microchannel plate photomultiplier tubes along with the detector response at high event rates. The detector has a single photoelectron timing resolution of 30ps at low rates (10kHz). We show that both the gain and the timing start to deteriorate around 1MHz with 20 photoelectrons per channel at 104 target gain, giving the current per unit of area limits of 1.38 μA∕cm2 and 2.38 μA∕cm2 for the two tested devices. Photo-multiplier tubes with lower micro-channel plate resistivity exhibit a better rate capability due to the faster replenishment of the charge inside the microchannels. As we demonstrate, another method to improve the rate capability is to operate the photon detector tubes at a lower gain by reducing the supply voltage and compensating for the loss of amplitude by an additional amplification stage at the expense of the achieved timing resolution. The tube active area over which the beam is spread also plays a role since the same amount of light yields a better rate capability when spread over a larger area. The tubes exposed to high event rates showed an uncharacteristically slow recovery back to its initial gain with 80% of the initial gain recovered only after several tens of minutes.

Anode-coupled readout for light collection in Liquid Argon TPCs

This paper will discuss a new method of signal read-out from photon detectors in ultra-large, underground liquid argon time projection chambers. In this design, the signal from the light collection system is coupled via capacitive plates to the TPC wire-planes. This signal is then read out using the same cabling and electronics as the charge information. This greatly benefits light collection: it eliminates the need for an independent readout, substantially reducing cost; it reduces the number of cables in the vapor region of the TPC that can produce impurities; and it cuts down on the number of feed-throughs in the cryostat wall that can cause heat-leaks and potential points of failure. We present experimental results that demonstrate the sensitivity of a LArTPC wire plane to photon detector signals. We also simulate the effect of a 1 μs shaping time and a 2 MHz sampling rate on these signals in the presence of noise, and find that a single photoelectron timing resolution of ∼30 ns can be achieved.

Frontend electronics for high-precision single photo-electron timing using FPGA-TDCs

The next generation of high-luminosity experiments requires excellent particle identification detectors which calls for Imaging Cherenkov counters with fast electronics to cope with the expected hit rates. A Barrel DIRC will be used in the central region of the Target Spectrometer of the planned PANDA experiment at FAIR. A single photo-electron timing resolution of better than 100ps is required by the Barrel DIRC to disentangle the complicated patterns created on the image plane. R&D studies have been performed to provide a design based on the TRB3 readout using FPGA-TDCs with a precision better than 20ps RMS and custom frontend electronics with high-bandwidth pre-amplifiers and fast discriminators. The discriminators also provide time-over-threshold information thus enabling walk corrections to improve the timing resolution. Two types of frontend electronics cards optimised for reading out 64-channel PHOTONIS Planacon MCP-PMTs were tested: one based on the NINO ASIC and the other, called PADIWA, on FPGA discriminators. Promising results were obtained in a full characterisation using a fast laser setup and in a test experiment at MAMI, Mainz, with a small scale DIRC prototype.

Single photoelectron timing resolution of SiPM as a function of the bias voltage, the wavelength and the temperature

This work reports on Silicon Photomultipliers (SiPM) timing resolution measurements performed at the picosecond level at Laboratory of Linear Accelerator (LAL), In2p3- CNRS.The dependence of Single Photoelectron Timing Resolution (SPTR) with the applied voltage, wavelength of the light and the temperature was measured for detectors from Hamamatsu Photonics, AdvanSiD and Sensl with an active area of 1 and 9mm2.The SPTR improves with the bias voltage increase. No significant variation of SPTR was observed with the temperature change. We also observed a weak variation of it as a function of the wavelength of the light. The best SPTR measured was about 120ps (FWHM).

Tests of timing properties of silicon photomultipliers

Timing measurements of Silicon Photomultipliers (SiPM) [1,2] at the picosecond level were performed at Fermilab. The core timing resolution of the electronic measurement technique is approximately 2 ps. The single photoelectron time resolution (SPTR) was measured for the signals coming from the SiPM's. A SPTR of about one hundred picoseconds was obtained for SiPM's illuminated by laser pulses. The dependence of the SPTR on applied bias voltage and on the wavelength of the light was measured. A simple model is proposed to explain the difference in the SPTR for blue and red light. A time of flight system based on the SiPM's, with quartz Cherenkov radiators, was tested in a proton beam at Fermilab. The time resolution obtained is 35 ps per SiPM. Finally, requirements for the SiPM's temperature and bias voltage stability to maintain the time resolution are discussed.

Timing by silicon photomultiplier: A possible application for TOF measurements

The Silicon Photomultiplier (SiPM) is intrinsically a very fast device, its single photoelectron timing resolution is about 100 ps FWHM. Therefore real timing properties of the system scintillator+SiPM is determined mostly by timing properties of the scintillator+light collection system. We present the experimental results for timing properies of SiPM+scintillator (or Cherenkov radiator) for two cases: (1) timing resolution in a few GeV electron beam with fast plastic scintillator or Cherenkov radiator+SiPMs with a size of 1×1 mm 2 and 3×3 mm 2 and (2)time-of-flight resolution for detection of 511 KeV photons by two LSO crystals+SiPM (3×3 mm 2), as a possible application for PET.

Influence of incident light wavelength on time jitter of fast photomultipliers

The study of the single photoelectron time resolution as a function of the wavelength of the incident light was performed for a 56 CVP photomultiplier having an S-1 photocathode. The light flash from the XP22 light emitting diode generator was passed through passband filters and illuminated the 5 mm diameter central part of the photocathode. A significant increase of the time resolution above 30% was observed when the wavelength of the incident light was changed from 790 nm to 580 nm. This gives experimental evidence that the time jitter resulting from the spread of the initial velocity of photoelectrons is proportional to the square root of the maximal initial energy of photoelectrons. Based on this conclusion the measured time jitter of C31024, RCA8850 and XP2020 photomultipliers with the use of the XP22 light emitting diode at 560 nm light wavelength was recalculated to estimate the time jitter at 400 nm near the maximum of the photocathode sensitivity. It shows an almost twice larger time spread at 400 nm for the C31024 and RCA8850 with a high gain first dynode and an about 1.5 times larger time spread for the XP2020 photomultiplier, than those measured at 560 nm.