Rui Gao

Abstract:

The TORCH detector provides low-momentum particle identification, combining Time of Flight (TOF) and Cherenkov techniques to achieve charged particle pi/K/p separation between 2–20 GeV/c over a flight distance of 10 m. The measurement requires a timing resolution of 70 ps for single Cherenkov photons. For precision photon detection, customised Micro-Channel Plate Photomultiplier Tubes (MCP-PMTs) with high precision TOF measurement electronics have been developed. The electronics measures time-over-threshold from the MCP-PMT and features a 10-Gigabit Ethernet readout. This paper reports the design and performance of a 5120-channel system which currently instruments a pair of MCP-PMTs, but has the capacity to read out ten customised MCP-PMT devices in the future.

Abstract:

Photek (U.K.) and the TORCH collaboration are undertaking a three year development program to produce a novel square MCP-PMT for single photon detection. The TORCH detector aims to provide particle identification in the 2-10 GeV/c momentum range, using a Time-of-Flight method based on Cherenkov light. It is a stand-alone R&D; project with possible application in LHCb, and has been proposed for the LHCb Upgrade. The Microchannel Plate (MCP) detector will provide a single photon timing accuracy of 40 ps, and its development will include the following properties: (i) Long lifetime up to at least 5 C/cm²; (ii) Multi-anode output with a spatial resolution of 6 mm and 0.4 mm respectively in the horizontal and vertical directions, incorporating a novel charge-sharing technique; (iii) Close packing on two opposing sides with an active area fill factor of 88% in the horizontal direction. Results from simulations modelling the MCP detector performance factoring in the pulse height variation from the detector, NINO threshold levels and potential charge sharing techniques that enhance the position resolution beyond the physical pitch of the pixel layout will be discussed. Also, a novel method of coupling the MCP-PMT output pads using Anisotropic Conductive Film (ACF) will be described. This minimises parasitic input capacitance by allowing very close proximity between the frontend electronics and the MCP detector.

Abstract:

The TORCH detector is proposed for the low-momentum particle identification upgrade of the LHCb experiment. It combines Time-Of-Flight and Cherenkov techniques to achieve charged particle separation up to 10 GeV/c. This requires a time resolution of 70 ps for single photons. Existing electronics has already demonstrated a 26 ps intrinsic time resolution; however the channel count and density need improvements for future micro-channel plate devices. This paper will report on a scalable design using custom ASICs (NINO-32 and HPTDC). The system provides up to 8 × 64 channels for a single micro-channel plate device. It is also designed to read out micro-channel plate tubes with charge-sharing technique.

Abstract:

The Time Of internally Reflected Cherenkov light (TORCH) detector is under development. Charged particle tracks passing through a 1 cm plate of quartz will generate the Cherenkov photons, and their arrival will be timed by an array of micro-channel plate photon detectors. As part of the TORCH R&D; studies, commercial and custom-made micro-channel plate detectors are being characterized. The final photon detectors for this application are being produced in a three-phase program in collaboration with industry. Custom-made single-channel devices with extended lifetime have been manufactured and their performance is being systematically investigated in the laboratory. Optical studies for the preparation of beam and laboratory tests of a TORCH prototype are also underway.

Abstract:

Timing Of internally Reflected CHerenkov photons (TORCH) is a time-of-flight detector proposed for particle identification at low momentum. Charged particles passing through a plane of quartz produce Cherenkov light, some of which is trapped within the plane by total internal reflection and then emerges at the edges. There the photons are focused onto micro-channel plate photon detectors that register their position and arrival time. This allows reconstructing the photon trajectories in quartz and determining the particle crossing time. Commercial micro-channel plate tubes can achieve the required timing resolution, but their anode spatial segmentation is too coarse, at least in one dimension. In addition, these devices must survive a number of years in a high occupancy environment. Micro-channel plate tubes specifically dedicated to the TORCH are currently being designed, constructed and prototyped in collaboration with industry. In the present paper, results from commercial and dedicated devices are reported. © 2014 Elsevier B.V. All rights reserved.