E. Cantatore

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

The Omega3/LHC1 pixel detector readout chip comprises a matrix of 128 × 16 readout cells of 50 μm × 500 μm 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 ∼ 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 μs have been measured. The results may be improved by further optimization.

Pixel readout electronics development for the ALICE pixel vertex and LHCb RICH detector

The ALICE1LHCB pixel readout chip emerged from previous experience at CERN. The RD-19 collaboration provided the basis for the installation of a pixel system in the WA97 and NA57 experiments. Operation in these experiments was key in the understanding of the system issues. In parallel the RD-49 collaboration provided the basis to obtain radiation tolerance in commercial submicron CMOS through special circuit layout. The new ALICE1LHB chip was developed to serve two different applications: particle tracking in the ALICE Silicon Pixel Detector and particle identification in the LHCb Ring Imaging Cherenkov detector. To satisfy the different needs for these two experiments, the chip can be operated in two different modes. In tracking mode all the 50 μm×425 μm pixel cells in the 256×32 array are read out individually, whilst in particle identification mode they are combined in groups of 8 to form a 32×32 array of 400 μm×425 μm cells. The circuit is currently being manufactured in a commercial 0.25 μm CMOS technology.

Pixel readout chips in deep submicron CMOS for ALICE and LHCb tolerant to 10 Mrad and beyond

The ALICE1LHCB chip is a mixed-mode integrated circuit designed to read out silicon pixel detectors for two different applications: particle tracking in the ALICE Silicon Pixel Detector and particle identification in the LHCb Ring Imaging Cherenkov detector. To satisfy the different needs for these two experiments, the chip can be operated in two different modes. In tracking mode all the 50 μm×425 μm pixel cells in the 256×32 array are read out individually, whilst in particle identification mode they are combined in groups of 8 to form a 32×32 array of 400 μm×425 μm cells. Radiation tolerance was enhanced through special circuit layout. Sensitivity to coupling of digital signals into the analog front end was minimized. System issues such as testability and uniformity further constrained the design. The circuit is currently being manufactured in a commercial 0.25 μm CMOS technology.

Experience with a 30 cm2 silicon pixel plane in CERN experiment WA97

Abstract A multi-chip, large area hybrid silicon pixel detector has been integrated in a particle physics experiment for the first time. The plane had 72K 75 μ m × 500 μ m sensor elements, covering a total area of about 30 cm 2 . It was constructed and characterized in a collaboration between heavy-ion experiment WA97 and R&D project RD19. Several such planes will be incorporated in a hyperon telescope, in order to improve tracking in the high multiplicity environment of central lead-lead collisions at the SPS. Results on the characterization of this detector in a proton beam at the Omega spectrometer at CERN are presented and discussed.

An introduction to deep submicron CMOS for vertex applications

Abstract Microelectronics has become a key enabling technology in the development of tracking detectors for High Energy Physics. Deep submicron CMOS is likely to be extensively used in all future tracking systems. Radiation tolerance in the Mrad region has been achieved and complete readout chips comprising many millions of transistors now exist. The choice of technology is dictated by market forces but the adoption of deep submicron CMOS for tracking applications still poses some challenges. The techniques used are reviewed and some of the future challenges are discussed.

Construction and characterization of a 117 cm/sup 2/ silicon pixel detector

A silicon pixel detector, developed in RD19, and consisting of 4 planes, /spl sim/30 cm/sup 2/ each, is operating for the first time in the lead ion experiment WA97 at CERN. The 288 CMOS readout chips are bump-bonded to 48 Si detector matrices, assembled in 8 identical arrays. The total number of pixel cells is nearly 300000 and each cell, 75 /spl mu/m/spl times/500 /spl mu/m, contains a complete signal processing chain. Overall dead area is less than 3%. >

Performance of 0.5 × 106 sensitive elements pixel telescope in the WA97 heavy ion experiment at CERN

Abstract A silicon pixel telescope, consisting of seven planes for a total of about 0.5 M sensor elements with size of 75 μ m × 500 μ m, was successfully employed in the WA97 experiment at CERN. We describe here the overall performance of the detector; we also report some early results from PbPb and p-Pb runs, showing the powerful capability to measure particle momenta and the effective mass of hyperons with a good resolution.

A front-end for silicon pixel detectors in ALICE and LHCb

A new front-end for a pixel detector readout chip was designed. A non-standard topology was used to achieve low noise and fast return to zero of the preamplifier to be immune to pile-up of subsequent input signals. This front-end has been implemented on a pixel detector readout chip developed in a commercial 0.25 μm CMOS technology for the ALICE and LHCb experiments. This technology proved to be radiation tolerant when special layout techniques are used, and provides sufficient density for these applications. The chip is a matrix of 32 columns each containing 256 readout cells. Each readout cell comprises this front-end and digital readout circuitry, and has a static power consumption of about 60 μW.

Determination of the event centrality in the WA97 and NA57 experiments

The procedure employed by the WA97 and NA57 experiments to determine the number of wounded nucleons in different Pb + Pb centrality classes is discussed. We will also compare different centrality scales and their influence on the measurement of the centrality dependence of strange particle yields.

DI-V

The first results on V0-V0 pairs, namely invariant masses and HBT correlations, obtained by the WA97 experiment in Pb-Pb collisions are presented. There is no evidence for any resonance signal.