An ISPA-camera for gamma rays

With the recently developed ISPA (Imaging Silicon Pixel Array)-tube attached either to a planar YAlO3(Ce) (YAP) disc (1mm thick) or to a matrix of optically-separated YAP-crystals (5mm high, 0.6 x 0.6 mm2 cross-section) we achieved high spatial resolution of 57Co-122 keV photons. The vacuum-sealed ISPA-tube is only 4 cm long with 3.5 cm diameter and consists of a photocathode viewed at 3 cm distance by a silicon pixel chip, directly detecting the photoelectrons. The chip-anode consists of 1024 rectangular pixels with 75 µm x 500 µm edges, each bump-bonded to their individual front-end electronics. The total pixel array read-out time is 10 µs. The measured intrinsic spatial resolutions (FWHM) of this ISPA-camera are 700 µm (planar YAP) and 310 µm (YAP-matrix). Apart from its already demonstrated application for particle tracking with scintillating fibres, the ISPA-tube provides also an excellent tool in medicine, biology and chemistry

Beam tests of a large-scale TORCH time-of-flight demonstrator

The TORCH time-of-flight detector is designed to provide particle identification in the momentum range 2-10 GeV/c over large areas. The detector exploits prompt Cherenkov light produced by charged particles traversing a 10 mm thick quartz plate. The photons propagate via total internal reflection and are focused onto a detector plane comprising position-sensitive Micro-Channel Plate Photo-Multiplier Tubes (MCP-PMT) detectors. The goal is to achieve a single-photon timing resolution of 70 ps, giving a timing precision of 15 ps per charged particle by combining the information from around 30 detected photons. The MCP-PMT detectors have been developed with a commercial partner (Photek Ltd, UK), leading to the delivery of a square tube of active area 53 $\times$ 53mm$^2$ with a granularity of 8 $\times$ 128 pixels equivalent. A large-scale demonstrator of TORCH, having a quartz plate of dimensions 660 $\times$ 1250 $\times$ 10 mm$^3$ and read out by a pair of MCP-PMTs with custom readout electronics, has been verified in a test beam campaign at the CERN PS. Preliminary results indicate that the required performance is close to being achieved. The anticipated performance of a full-scale TORCH detector at the LHCb experiment is presented.Comment: 12 pages, 7 figures, Paper submitted to Nuclear Instruments & Methods in Physics Research, Section A - Special Issue VCI 201

Status of the TORCH time-of-flight project

TORCH is a time-of-flight detector, designed to provide charged pi/K particle identification up to a momentum of 10 GeV/c for a 10 m flight path. To achieve this level of performance, a time resolution of 15 ps per incident particle is required. TORCH uses a plane of quartz of 1 cm thickness as a source of Cherenkov photons, which are then focussed onto square Micro-Channel Plate Photomultipliers (MCP-PMTs) of active area 53 x 53 mm^2, segmented into 8 x 128 pixels equivalent. A small-scale TORCH demonstrator with a customised MCP-PMT and associated readout electronics has been successfully operated in a 5 GeV/c mixed pion/proton beam at the CERN PS facility. Preliminary results indicate that a single-photon resolution better than 100 ps can be achieved. The expected performance of a full-scale TORCH detector for the Upgrade II of the LHCb experiment is also discussed.Comment: 9 pages, 6 figures, Paper submitted to Nuclear and Methods A : Proceedings of the 10th International Workshop on Ring Imaging Cherenkov Detectors (RICH 2018), Moscow, Russia, July 29 to August 4 201

Irradiation and SPS Beam Tests of the Alice1LHCb Pixel Chip

The Alice1LHCb front-end chip has been designed for the ALICE pixel and the LHCb RICH detectors. It is fabricated in a commercial 0.25 µm CMOS technology, with special design techniques to obtain radiation tolerance. The chip has been irradiated with low energy protons and heavy ions, to determine the cross-section for Single Event Upsets (SEU), and with X-rays to evaluate the sensitivity to total ionising dose. We report the results of those measurements. We also report preliminary results of measurements done with 150 GeV pions at the CERN SPS

LHC1: a semiconductor pixel detector readout chip with internal, tunable delay providing a binary pattern of selected events

The Omega3/LHCl pixel detector readout chip comprises a matrix of 128 X 16 readout cells of 50 mu m X 500 mu m and peripheral functions with 4 distinct modes of initialization and operation, together more than 800 000 transistors. Each cell contains a complete chain of amplifier, discriminator with adjustable threshold and fast-OR output, a globally adjustable delay with local fine-tuning, coincidence logic and memory. Every cell can be individually addressed for electrical test and masking, First results have been obtained from electrical tests of a chip without detector as well as from source measurements, The electronic noise without detector is similar to 100 e(-) rms. The lowest threshold setting is close to 2000 e(-) and non-uniformity has been measured to be better than 450 e(-) rms at 5000 e(-) threshold. A timewalk of < 10 ns and a precision of < 6 ns rms on a delay of 2 mu s have been measured. The results may be improved by further optimization