abstract

The development of Low-Gain Avalanche Diodes (LGADs) has made possible to manufacture silicon detectors with output signals that are about a factor of 10 larger than those of traditional sensors. This increased output brings many benefits such as the possibility of developing thin detectors with large enough signals, a good immunity towards low charge collection efficiency and it is key for excellent timing capabilities. In this paper, we report on the development of silicon sensors based on the LGAD design optimized to achieve excellent timing performance, the so-called Ultra-Fast Silicon Detectors (UFSDs). In particular, we demonstrate the possibility of obtaining ultra-fast silicon detectors with time resolution of less than 30 picosecond.

abstract

The authors discuss a possible technique to measure the arrival time of minimum ionizing particle with tens of picosecond resolution using diamond detector parallel to tracks and show preliminary testbeam results obtained with 5 GeV electrons and polycrystalline diamond strip detectors.

abstract

Test and characterization of the new generation of fast detectors are pushing the time precision required for associated electronics towards the picosecond level. The WaveCatcher board family has been developed for proposing a powerful alternative to ADC-based digitizers or oscilloscopes. It permits a 12-bit waveform digitization over up to 64 channels, with a 500-MHz bandwidth and a sampling rate up to 3.2 GS/s, together with a time precision better than 5 ps rms. Thanks to the powerful software developed for the boards, measurement is made easy since the PC is transformed into an oscilloscope. It also permits saving data files directly on disk. The WaveCatcher systems actually are great tools for characterization of detectors down to a few ps level. An increasing number of labs or companies are now using the WaveCatcher boards worldwide on their test benches or physics experiments.

abstract

SAMPIC0 is a Time and Waveform to Digital Converter (TWDC) multichannel chip. Each of its 16 channels associates a DLL-based TDC providing a raw time with an ultra-fast analogue memory allowing fine timing extraction as well as other parameters of the pulse. Each channel also integrates a discriminator that can trigger it independently or participate to a more complex trigger. After triggering, the analogue data are digitized by an on-chip ADC and only those corresponding to a region of interest are sent serially to the acquisition. The paper describes the architecture of SAMPIC0 and reports its main measured performance. Measurements on this chip have shown timing performance in the range of 15 ps RMS without correction decreased to less than 5 ps RMS after a simple calibration.

abstract

The paper addresses the architectural patterns and programming principles of Mordicus-hw, a framework designed to optimize collaborative development between electronics and software engineers by providing them with software tools that are adapted to their respective activities. When designing specific modules, electronics engineers are often led to write small “quick and dirty” C/C++ programs in order to test and debug their design. But the actual software that they have developed to run and test their hardware designs is often discarded afterwards because it lacks the re-usability required by the application modules developed by software engineers. The Mordicus-hw framework addresses these issues, favours collaborative design and development between electronics, and software engineers by providing a simplified, high-level, script-based register programming platform.

abstract

The planned \(\overline {\rm P}\)ANDA experiment at the new FAIR facility requires a very good hadron identification, which will be achieved with two DIRC detectors. Microchannel-plate (MCP) photomultipliers (PMTs) are foreseen for the read-out of these devices, due to their usability in high magnetic fields of up to 2 T and their excellent time resolution. However, the lifetime under photon irradiation was not sufficient until recently, but the latest sensors seem to overcome this last restriction. We have tested the lifetime of several MCP-PMTs of different manufacturers under \(\overline {\rm P}\)ANDA conditions. The main goal was to achieve comparable data for all potential sensors simultaneously. The measurement procedure requires the permanent monitoring of the illumination and irregular interruptions after several days (typ. 3–10) to measure the dark count rate, gain and the spectral quantum efficiency of all sensors. On larger time scales of 2–4 months the whole surface of the sensors is scanned to determine faster aging areas. Our results reveal excellent lifetime performances for MCP-PMTs with MCPs coated by an atomic layer deposition (ALD) technique. Especially PHOTONIS XP85112/A1-HGL sensors seem to fulfill all requirements.

abstract

TORCH is an innovative high-precision time-of-flight system to provide particle identification in the difficult intermediate momentum region up to 10 GeV/\(c\). It is also suitable for large-area applications. The detector provides a time-of-flight measurement from the imaging of Cherenkov photons emitted in a 1 cm thick quartz radiator. The photons propagate by total internal reflection to the edge of the quartz plate, where they are focused onto an array of photon detectors at the periphery. A time-of-flight resolution of about 10–15 ps per incident charged particle needs to be achieved for a three sigma kaon–pion separation up to 10 GeV/\(c\) momentum for the TORCH located 9.5 m from the interaction point. Given \(\sim 30\) detected photons per incident charged particle, this requires measuring the time-of-arrival of individual photons to about 70 ps. This paper will describe the design of a TORCH prototype involving a number of ground-breaking and challenging techniques.

abstract

The study of exclusive reactions \(p+p \rightarrow p + X + p\) at the LHC at high luminosity requires a high precision measurement of the time difference \(\Delta t\) between the protons to reduce pile-up background. With \(\sigma (t) = 15\) ps the \(z\)-position of the interaction, if and only if they came from the same collision, is determined to \(\sigma (z) = 3\) mm. I discuss the development of quartz or sapphire Cherenkov counters with this goal.

abstract

We characterize the nature of the time dispersion in scintillation detectors caused by path length differences of the scintillation photons as they travel from their generation point to the photodetector. Using Monte Carlo simulation, we find that the initial portion of the distribution (which is the only portion that affects the timing resolution) can usually be modeled by an exponential decay. The peak amplitude and decay time depend both on the geometry of the crystal, the position within the crystal that the scintillation light originates from, and the surface finish. In a rectangular parallelpiped LSO crystal with 3 mm \(\times \) 3 mm cross section and polished surfaces, the decay time ranges from 10 ps (for interactions 1 mm from the photodetector) up to 80 ps (for interactions 50 mm from the photodetector). Over that same range of distances, the peak amplitude ranges from 100% (defined as the peak amplitude for interactions 1 mm from the photodetector) down to 4% for interactions 50 mm from the photodetector. Higher values for the decay time are obtained for rough surfaces, but the exact value depends on the simulation details. Estimates for the decay time and peak amplitude can be made for different cross section sizes via simple scaling arguments.

abstract

We present the physics motivation of detecting intact protons in the final state at the LHC in the ATLAS and CMS experiments, as well as the importance of timing measurement, in particular, to reject pile-up background. Different kinds of timing detectors being studied are presented briefly.

abstract

The PhaseII Upgrades of CMS are being planned for the High Luminosity LHC (HL-LHC) era when the mean number of interactions per beam crossing (“in-time pileup”) is expected to reach \(\sim 140\)–200. The potential backgrounds arising from mis-associated jets and photon showers, for example, during event reconstruction could be reduced if physics objects are tagged with an “event time”. This tag is fully complementary to the “event vertex” which is already commonly used to reduce mis-reconstruction. Since the tracking vertex resolution is typically \(\sim 10^{-3} (\sim \frac {50\,\mu {\mathrm {m}}}{4.8\,{\mathrm {cm}}}\)) of the rms vertex distribution, whereas only \(\sim 10^{-1}\) (i.e. 20 vs. 170 picoseconds (psec)) is demonstrated for timing, it is often assumed that only photon (i.e. EM calorimeter or shower-max) timing is of interest. We show that the optimal solution will likely be a single timing layer which measures both charged particle and photon time (a pre-shower layer).

abstract

We present the custom-designed fast analog and digitizer electronics developed for the fast time-of-flight Cherenkov detectors of the ATLAS Forward Proton project at the CERN Large Hadron Collider. The electronics is designed to be radiation tolerant and deliver a timing resolution of 20 picoseconds or better per detector channel.

abstract

The principles of a time resolved single photon counting system, based on the hybrid GHz radio frequency photomultiplier tube, RF PMT, are presented. The time resolution and minimal time bin of the technique is about one picosecond. The average rate of the technique can reach GHz. The detection and readout systems are based on commercial microchannel plates, electron bombardment avalanche photodiodes and regular nanosecond electronics. Timing characteristics of the RF PMT were obtained by means of Monte Carlo simulations. For electron optics simulations, SIMION 8 software has been used. The operation of the dedicated GHz radio frequency deflector and a hybrid RF PMT was investigated by means of a thermionic electron source. Possible application at the LHC Atlas Forward Proton experiment is discussed.