Design of a monolithic HR-CMOS sensor chip for the CLIC silicon tracker

The CLIC Tracker Detector (CLICTD) is a monolithic active pixel sensor targeted at the tracking detector of a future experiment at the Compact Linear Collider (CLIC). The chip features a matrix of $16 \times 128$ cells, each cell measuring $300 \times 30\,\mu m^{2}$ . The cells are segmented in the long direction in order to maintain the benefits of the small collection electrode. In the digital logic, a simultaneous 8-bit Time of Arrival and 5-bit Time over Threshold measurement is performed. A 180 nm HR-CMOS Imaging Process was selected for the design of a chip that will meet the requirements of the tracker at CLIC. In this document, the CLICTD design and chip interface are presented

Equalization method for Medipix3RX

This paper describes a new method of threshold equalization for X-ray detectors based on the Medipix3RX ASIC, using electrical pulses to calibrate and correct for the threshold dispersion between pixels. This method involves a coarse threshold tuning, based on two 8 bits global DACs and which sets the range of variation of the threshold values; and a fine-tuning, based on two 5-bits adjustment DACs per pixel. As our fine-tuning approach is based on a state-of-the-art methodology, our coarse tuning relies on an original theoretical model. This model takes into account the noise level of the ASIC, which varies with temperature and received radiation dose. The experimental results using 300 μm Si sensor and Kα fluorescence of Zn show a global energy resolution improvement of 14% compared to previous equalization methods. We compared these results with the best achievable global energy resolution given by the resolution of individual pixels and concluded that the remaining 14% difference was due to the discretization error limited by the number of equalization bits

CLICTD: A monolithic HR-CMOS sensor chip for the CLIC silicon tracker

The CLIC Tracker Detector (CLICTD) is a monolithic pixelated sensor chip produced in a 180 nm imaging CMOS process with a high-resistivity epitaxial layer. The chip, designed in the context of the CLIC tracking detector study, comprises a matrix of 16 × 128 detector channels, each measuring 300 × 30 μm$^2$ . To ensure prompt charge collection, every channel is segmented in eight collection diodes, each containing a separate analog front-end. A simultaneous 8-bit time and 5-bit energy measurement is performed in the on-channel digital logic. The main design aspects as well as the first results from laboratory measurements with the CLICTD are presented

Proposal for LHCb RICH detector enhancements during LHC Long Shutdown 3

The prompt Cherenkov radiation and focusing optics of the RICH detectors result in time characteristics which are unique among large-volume detector systems. The time-of-arrival at the photon detectors of the Cherenkov photons corresponding to a given primary vertex can be predicted to within ten picoseconds. This property can be used to significantly improve the signal to noise ratio and thereby the PID performance of the detector and will ultimately allow the present system to withstand luminosities in excess of $10^{34}cm^{-2}s^{-1}$. To this end, we propose to integrate a new readout ASIC, the FastRICH, into the present system during the Long Shutdown 3 (LS3, 2026-2028). This will allow the system to timestamp each photon with an approximately 150 ps time resolution within a short gate of about 2 ns. This enhancement can be achieved at a limited cost, prepares for the Upgrade II RICH system overhaul and improves the hadronic PID performance for the physics programme of LHCb during Run 4

Imaging properties of the Medipix2 system exploiting single and dual energy thresholds

Low noise, high resolution and high dose efficiency are the common requirements for most X-ray imaging applications. Especially in medical applications the dose efficiency is a necessity for detector systems. We present the imaging performance of the Medipix2 readout chip bump bonded to a 300 mu m thick Si detector as a function of the detection threshold, a free parameter not available in conventional integrating imaging systems. Spatial resolution has been measured using the modulation transfer function (MTF) and it varies between 8.2 Ip/mm and 11.0 Ip/mm at 70%. An associated measurement of noise power spectrum (NPS) permits us to derive the detective quantum efficiency (DQE) which can be as a high as 25.5 % for a broadband incoming spectrum. The influence of charge diffusion in the sensor together with threshold variation in the readout chip is discussed. Although the Medipix2 system is used in photon counting mode with a single threshold in energy, the system is also capable of counting within a given energy window of down to ~1.4 keV. First measurements and images using this feature reveal capabilities that allow to identify fluorescence and other sources of disturbance

Backsplash Testbeam results for the SPD

A small fraction of the cascade developed in a calorimeter by the primary particle is emitted backward as radiation often called backsplash. A testbeam with electrons and pions has been done to complete previous studies of the effect of backsplash on the SPD (Scintillator Pad Detector), positioned just before the Preshower and ECAL system. The measurements and their comparison with GEANT3 and EGS4 simulations are presented in this note

Updated results on the Monte Carlo Simulation of the SPD/PRS Pulseshape

In this note a full Monte Carlo Simulation of the LHCb SPD/PRS subd etectors tile signal temporal shape is presented. Being this simulation too slow a fast Monte Carlo simulation is introduced to tune the free parameters from the full MC simulation. The pulseshape information is needed to be introduced in the general Monte Carlo Simulation (Gauss) and it is extracted from this fast simulation. The fast simulation is also applied for ECAL and HCAL to compare it to test-beam dat

Backsplash simulation and occupancies for the SPD

This note presents the results of a Monte Carlo simulation to study the limitations introduced by backscattered particles in the electron/gamma separation of the SPD subdetector of LHCb. In this occasion, lateral backsplash has been specially studied as a complement to previous studies, with electrons and photons of different energies as incident particles. In a second part, making use of these results and SICBMC information, the occupancies of the SPD expected in the real experiment are calculated