L. Ristori

The pion form factor has been measured in the space-like q2 region 0.014 to 0.26 (GeV/c)2 by scattering 300 GeV pions from the electrons of a liquid hydrogen target. A detailed description is given of the apparatus, data analysis and corrections to the data. The mean square charge radius extracted from the data is model-dependent. We find that a form which includes a realistic description of the form factor phase gives a similar results to the naive pole form, and conclude 〈r2π〉 = 0.438±0.008 fm2.

We present the first results of a measurement of the total cross-section σT in proton-proton collisions at equivalent laboratory momenta between 291 and 1480 GeV/c at the CERN Intersecting Storage Rings (ISR). The method is based on the measurement of the ratio of the total interaction rate and the machine luminosity. The data show an increase of about 10% in σT in this energy interval.

The negative kaon electromagnetic form factor has been measured in the space-like q2 range 0.015–0.10 (GeV/c)2 by the direct scattering of 250 GeV kaons from electrons at the CERN SPS. It is found that the kaon mean square charge radius 〈r2K〉 = 0.34 ± 0.05 fm2. From data collected simultaneously for πe scattering, the difference between the charged pion and kaon mean square radii (which is less sensitive to systematic errors) is found to be 〈r2π〉 − 〈r2K = 0.1 0 ± 0.045 fm2.

The CDF central and endwall hadron calorimeter covers the polar region between 30° and 150° and a full 2π in azimuth. It consists of 48 steel-scintillator central modules with 2.5 cm sampling and 48 steel-scintillator endwall modules with 5.0 cm sampling. A general description of the detector is given. Calibration techniques and performance are discussed. Some results of the test beam studies are shown.

A silicon microstrip vertex detector has been constructed and installed in the Collider Detector at Fermilab. The device has been designed to operate at a hadron collider. It began collecting data in May of 1992 and has functioned within specification. Technical details are presented on all aspects of the system and its performance.

We report a measurement of the negative pion electromagnetic form factor in the range of space-like four-momentum transfer 0.014 < q2 < 0.122 (GeV/c)2. The measurement was made by the NA7 collaboration at the CERN SPS, by observing the interaction of 300 GeV pions with the electrons of a liquid hydrogen target. The form factor is fitted by a pole form with a pion radius of 〈r2〈12 = 0.657 ± 0.012 fm.

The Collider Detector at Fermilab (CDF) experiment's Silicon Vertex Trigger (SVT) is a system of 150 custom 9U VME boards that reconstructs axial tracks in the CDF silicon strip detector in a 15μs pipeline. SVT's 35μm impact parameter resolution enables CDF's Level 2 trigger to distinguish primary and secondary particles, and hence to collect large samples of hadronic bottom and charm decays. We review some of SVT's key design features. Speed is achieved with custom VLSI pattern recognition, linearized track fitting, pipelining, and parallel processing. Testing and reliability are aided by built-in logic state analysis and test-data sourcing at each board's input and output, a common interboard data link, and a universal “Merger” board for data fan-in/fan-out. Speed and adaptability are enhanced by use of modern FPGAs.

We discuss the architecture of a device based on the concept of associative memory designed to solve the track finding problem, typical of high energy physics experiments, in a time span of a few microseconds even for very high multiplicity events. This “machine” is implemented as a large array of custom VLSI chips. All the chips are equal and each of them stores a number of “patterns”. All the patterns in all the chips are compared in parallel to the data coming from the detector while the detector is being read out.

The EM form factor of the pion has been studied in the time-like region by measuring σ(e+e− → π+π−) normalized to σ(e+e− → μ+μ−). Results have been obtained for q2 down to the physical threshold.

We present data on two-particle distributions in the approximate rapidity variable η = −1n tan θ/2 for secondaries produced in proton-proton collisions at the CERN Intersecting Storage Rings (ISR). The data at centre-of-mass energies of 23 and 62 GeV show the existence of energy-independent positive, short-range correlations between secondaries within the central region. Deviations from short-range correlation exist when one (or both) of the particles is near the boundary of the available phase space. In part, such deviations are interpreted as the effect of a diffractive-like component in multiparticle production.

A search for the exotic meson $X(5568)$ decaying into the $B^0_s \pi^{\pm}$ final state is performed using data corresponding to $9.6 \textrm{fb}^{-1}$ from $p{\bar p}$ collisions at $\sqrt{s} = 1960$ GeV recorded by the Collider Detector at Fermilab. No evidence for this state is found and an upper limit of 6.7\% at the 95\% confidence level is set on the fraction of $B^0_s$ produced through the $X(5568) \rightarrow B^0_s \, \pi^{\pm}$ process.

We describe a two level FASTBUS based trigger processor designed and built for the CDF detector at the Fermilab pp collider. The Level 1 decision is based on the global energy deposition in the calorimeters as well as on the presence of muon candidates and stiff tracks in the central drift chamber. The Level 1 decision is made in the 3.5 μs between beam crossings, incurring no deadtime while reducing a raw event rate of 50–75 kHz to a few kHz. The remaining events are passed on to Level 2. The Level 2 decision is driven by the topology of the event, operating on calorimeter clusters, central stiff tracks and muon candidates. Level 2 is designed to reduce the rate to 1–100 Hz, incurring less than 10% deadtime, before initiating readout of all the detector elements. A large fraction of the trigger hardware is used for both the Level 1 and Level 2 decisions.

An associative memory full-custom CMOS VLSI chip (AMchip), to be used in fast trigger systems for pattern recognition, has been designed and is being tested. The AMchip is a full-custom associative memory IC developed for high energy physics. It contains about 140000 MOS transistors, has been realized in 1.5- mu m, double-metal, silicon gate CMOS technology, and is housed in a 120-pin package. The AMchip has been designed to be used with any kind of detector which provides in the output the hit coordinates. Some preliminary tests have been done on the 55 prototypes received from the ES2 (European silicon structures) foundry. The performance test, limited by the equipment used, has shown that the AMchip can work with a 20-MHz clock.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Charmed meson pairs have been photoproduced coherently on an active silicon target. Ninety-eight decays have been analyzed and the lifetime of charged D's has been measured.

The Silicon Vertex Trigger (SVT) in the CDF experiment at Fermilab performs fast and precise track finding and fitting at the second trigger level and has been a crucial element in data acquisition for Run II physics. However, as luminosity rises, multiple interactions increase the complexity of events and thus the SVT processing time, reducing the amount of data CDF can record. The SVT upgrade aims to increase the SVT processing power to restore the original CDF DAQ capability at high luminosity. We describe the SVT upgrade, consisting of a new Associative Memory 16 times larger than the existing one, and new faster Track Fitter and Hit Buffer boards to take advantage of these patterns. We describe the existing system, the upgrade, tests and performance.

We present data on the semi-inclusive distributions of rapidities of secondary particles produced in pp collisions at very high energies. Our experiment was performed at the CERN Intersecting Storage Rings (ISR). The data given here, at centre-of-mass energies of √s=23 and 62 GeV, include the single-particle distributions and two-particle correlations. The semi-inclusive correlations show pronounced short-range correlation effects which have a width considerably narrower than in the case of inclusive correlations. We show that these short-range effects can be understood empirically in terms of three parameters whose energy and multiplicity dependence are studied. The data support the picture of multiparticle production in which clusters of small multiplicity and small dispersion are emitted with subsequent decay into hadrons.

The ϱ− radiative decay width has been measured by studying the production of ϱ− via the Primakoff effect by 200 GeV incident π− on Cu and Pb targets. This width was obtained by fitting the measured dσ/dt for ϱ production with the theoretical coherent differential cross section including both the electromagnetic and strong contributions. The measured radiative width value is 81 ± 4 ± 4 keV: it is consistent with the ratio Γ(ϱ → πγ)/Γ(ω → πγ) ∼ case:19 as expected from the vector dominance and the quark model.

A detector has been developed in our laboratory for proposed use in high energy experiments. It works as a MWPC in which the ionizing medium consists of a thin layer of silicon crystal. The results of the test carried out at CERN show that the detector is ideally suited for the detection of minimum ionizing particles and can provide very high spatial resolution.

We have measured the behaviour or charged-particle multiplicities as a function of the transverse momentum of photons produced at 90° in proton-proton collisions. The data were obtained at the CERN Intersecting Storage Rings (ISR) at a centre-of-mass energy of 53 GeV and cover the transverse momentum range 0 < p⊥ < 4.5 GeV/c. The total associated charge multiplicity increases with p⊥ and most of the increase is found in a very wide cone opposite the detected photons. Partial multiplicities in the direction of the photons vary only slightly with p⊥. However, multiplicities at small angles with respect to the beams decrease sharply with increasing p⊥.

For a number of interesting processes in the sector of heavy flavors, the quality of measurements made at hadron colliders is very similar to the quality achieved at e + e − colliders (known as B factories). The key to performing such measurements in a hadron environment is the ability to select rare processes from background in real time, that is, to trigger on them. Two distinctive features of heavy-flavor decays have been used for this purpose: the presence of leptons in the final state and secondary vertices produced by the relatively long lifetime. The selection of events based on long lifetime, although technically very challenging, is the most inclusive of all such techniques, allowing access to the widest range of channels. The focus of this review is on the innovative concepts that permitted the reconstruction of tracks produced in hadron collisions with sufficient speed and accuracy for use at trigger level to detect heavy-flavor decays.

We introduce a new pattern recognition algorithm for track finding in High Energy Physics Experiments based on an extension of the Hough Transform to multiple dimensions. A remarkable property of this algorithm is that the execution time is simply proportional to the total number of the hits to be processed, making it particularly attractive for high occupancy situations. The algorithm needs to be trained using a sufficiently large set of simulated tracks. The same track finding algorithm can be used for very different detector geometries and only the set of simulated tracks used for training needs to be changed. The particular structure of the algorithm also lends itself naturally to parallel hardware implementations which, combined with its intrinsic flexibility, should provide a most powerful tool for triggering at future colliders.

The SVT is an online tracker for the CDF upgrade which will reconstruct 2D tracks using information from the Silicon VerteX detector (SVXII) and Central Outer Tracker (COT). The precision measurement of the track impact parameter will then be used to select and record large samples of B hadrons. We discuss the overall architecture, algorithms, and hardware implementation of the system.

A new approach is proposed for fast track finding in position-sensitive detectors. The basic working principle is modeled on what is widely believed to be the low-level mechanism used by the eye to recognize straight edges. A number of receptors are tuned such that each one responds to a different range of track orientations, each track actually fires several receptors and an estimate of the orientation is obtained through interpolation. The feasibility of a practical device based on this principle and its possible implementation using currently available digital logic is discussed.

The Silicon Vertex Tracker (SVT), currently being built for the CDF II experiment, is a hardware device that reconstructs 2-D tracks online using measurements from the Silicon Vertex Detector (SVXII) and the Central Outer Tracker (COT). The precise measurement of the impact parameter of the SVT tracks will allow, for the first time in a hadron collider environment, to trigger on events containing B hadrons that are very important for many studies, such as CP violation in the b sector and searching for new heavy particles decaying to bb̄ . In this report we describe the overall architecture, algorithms and the hardware implementation of the SVT.

The design is presented for a device presently being built to perform on line track finding and reconstruction for the CDF (Collider Detector at Fermilab) Silicon Vertex Detector (120 k channels). This device will provide track impact parameter information for the CDF Level 2 trigger decision, thus allowing CDF to trigger on events containing a long lived particle, in particular a b-quark. It will be the first device with such a capability installed at a proton-antiproton collider. The capability to separate b decays early in the trigger process is vital to the CDF program to collect a high statistic b sample to attack the study of CP violation in the b sector. Moreover SVT will open access to non-leptonic b decays like B/spl rarr//spl pi//spl pi/.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A telescope made up of thin silicon detectors was built and used as a live target in a high-energy photoproduction experiment at the CERN Super Proton Synchrotron. Its working principles, construction technique, and the results of tests are reported. This telescope will allow measurement of the decay path in the range 300–10000 μm.

The NAl (FRAMM) experiment, under construction for the CERN-SPS North Area, deals with more than 1000 counter signals which have to be combined together in order to build sophisticated and highly selective triggers. These requirements have led to the development of a low cost, combinatorial, fast electronics which can replace, in an advantageous way, the standard NIM electronics at the trigger level. The essential performances of the basic circuit are: 1) programmability of any desired logical expression; 2) trigger time independent of the chosen expression; 3) reduced cost and compactness due to the use of commercial RAMs, PROMs, and PLAs; 4) short delay, less than 20 ns, between input and output pulses.

The SVX vertex detector has been very successful in heavy flavor physics at CDF, playing a significant role in both top and bottom analyses. SVX′, a radiation hard version of SVX, is presently taking data. In 1998 the Main Injector upgrade to the accelerator complex at Fermilab will provide a significant increase in luminosity, and will require a new vertex detector, SVX II. The specifications and design considerations for this detector are discussed.

Abstract An associative memory to be used for super-fast track finding in future high energy physics experiments, has been implemented on silicon as a full-custom CMOS VLSI chip (the AMchip). The first prototype has been designed and successfully tested at INFN in Pisa. It is implemented in 1.6 μm, double metal, silicon gate CMOS technology and contains about 140 000 MOS transistors on a 1 × 1 cm 2 silicon chip.

We describe a very fast algorithm for track finding, which is applicable to a whole class of detectors like drift chambers, silicon microstrip detectors, etc. The algorithm uses a pattern bank stored in a large memory and organized into a tree structure.

Abstract All CDF event data are collected in a multilevel FASTBUS network. At the lowest level of this network, MEP/MX and SSP scanners read and buffer data from RABBIT and FASTBUS front end systems. Operation of these front end scanners is coordinated by the Trigger Supervisor module which initiates parallel readout after receiving Level 1 and Level 2 triggers. Dataflow from scanners to consumer processes on host VAX computers is supervised by the Buffer Manager which directs an Event Builder to collect and format data from a set of scanner modules. This system is designed to allow partitioning into semi-independent sections for parallel development and calibration studies.

We report on the performance of a specialized processor capable of reconstructing charged particle tracks in a realistic LHC silicon tracker detector, at the same speed of the readout and with sub-microsecond latency. The processor is based on an innovative pattern-recognition algorithm, called “artificial retina algorithm”, inspired from the vision system of mammals. A prototype of the processor has been designed, simulated, and implemented on Tel62 boards equipped with high-bandwidth Altera Stratix III FPGA devices. The prototype is the first step towards a real-time track reconstruction device aimed at processing complex events of high-luminosity LHC experiments at 40 MHz crossing rate.

The first observation of neutral pion production in πe inelastic scattering is presented. The cross section at 300 GeV for |t‖>62;10−3 (GeV / c)2 is 2.11 ± 0.47 nb, in good agreement with the theory of PCAC anomalies with 3 quark colours.

The CDF Online Silicon Vertex Tracker (SVT) reconstructs 2D tracks by linking hit positions measured by the Silicon Vertex Detector to the Central Outer Chamber tracks found by the eXtremely Fast Tracker (XFT). The system has been completely built and assembled and it is now being commissioned using the first CDF run II data. The precision measurement of the track impact parameter will allow triggering on B hadron decay vertices and thus investigating important areas in the B sector, like CP violation and Bs mixing. In this paper we briefly review the architecture and the tracking algorithms implemented in the SVT and we report on the performance of the system achieved in the early phase of CDF run II.

The online silicon vertex tracker (SVT) is the new trigger processor dedicated to the two-dimensional (2-D) reconstruction of charged particle trajectories at the Level 2 of the Collider Detector at Fermilab (CDF) trigger. The SVT links the digitized pulse heights found within the silicon vertex detector to the tracks reconstructed in the central outer tracker by the Level 1 fast-track finder. Preliminary tests of the system took place during the October 2000 commissioning run of the Tevatron Collider. During the April-October 2001 data taking, it was possible to evaluate the performance of the system. In this paper, we review the tracking algorithms implemented in the SVT and we report on the performance achieved during the early phase of run II.

The Hit Buffer is part of the Silicon Vertex Tracker [1], a trigger processor dedicated to the reconstruction of particle trajectories in the Silicon Vertex Detector [2] and the Central Tracking Chamber of the Collider Detector at Fermilab. The Hit Buffer is a high speed data-traffic node, where thousands of words are received in arbitrary order and simultaneously organised in an internal structured data base, to be later promptly retrieved and delivered in response to specific requests. The Hit Buffer is capable to process data at a rate of 25 MHz, thanks to the use of special fast devices like Cache-Tag RAMs and high performance Erasable Programmable Logic Devices from the XILINX XC7300 family.

Resolution and linearity of the position measurement of Pisa multi-electrode silicon detectors are presented. The detectors are operated in slightly underdepleted mode and take advantage of their intrinsic resistivity for resistive charge partition between adjacent strips. 22 μm resolution is achieved with readout lines spaced 300 μm. Possible applications in colliding beam experiments for the detection of secondary vertices are discussed.

The Silicon Vertex Trigger (SVT) provides the CDF experiment with a powerful tool for fast and precise track finding and fitting at trigger level. The system enhances the experiment's reach on B-physics and large PT-physics coupled to b quarks. We review the main design features and the performance of the SVT with particular attention to the recent upgrade that improved its capabilities. Finally, we will focus on additional improvements of the functionality of such a system in a more general experimental context.

The CDF Run II level 2 calorimeter trigger is implemented in hardware and is based on a simple algorithm that was used in Run I. This system has worked well for Run II at low luminosity. As the Tevatron instantaneous luminosity increases, the limitation due to this simple algorithm starts to become clear. As a result, some of the most important jet and MET (missing ET) related triggers have large growth terms in cross section at higher luminosity. In this paper, we present an upgrade of the L2CAL system which makes the full calorimeter trigger tower information directly available to the level 2 decision CPU. This upgrade is based on the Pulsar, a general purpose VME board developed at CDF and already used for upgrading both the level 2 global decision crate and the level 2 silicon vertex tracking. The upgrade system allows more sophisticated algorithms to be implemented in software and both level 2 jets and MET can be made nearly equivalent to offline quality, thus significantly improving the performance and flexibility of the jet and MET related triggers. This is a natural expansion of the already-upgraded level 2 trigger system, and is a big step forward to improve the CDF triggering capability at level 2. This paper describes the design, the hardware and software implementation and the performance of the upgrade system.

We present the results of an R&D study of a specialized processor capable of precisely reconstructing events with hundreds of charged-particle tracks in pixel detectors at 40 MHz, thus suitable for processing LHC events at the full crossing frequency. For this purpose we design and test a massively parallel pattern-recognition algorithm, inspired by studies of the processing of visual images by the brain as it happens in nature. We find that high-quality tracking in large detectors is possible with sub-μs latencies when this algorithm is implemented in modern, high-speed, high-bandwidth FPGA devices. This opens a possibility of making track reconstruction happen transparently as part of the detector readout.

Describes the germanium monlithic detector and discusses its performance. The detector is a parallelepiped 5 x 5 x 20 mm in volume with 48 electrodes 20 mm long, 50 microns wide and spaced 50 microns one from the other deposited on one face. Presents a sketch of the detector and its working principle. To obtain a finer granularity, a telescope of 40 layers of silica was substituted with a target made out of a single block of germanium followed by a silicon telescope.

An experiment to study high energy γ rays from localized cosmic sources is described. A number of Al mirrors reflects the Cherenkov light emitted by the showers into photosensitive gas chambers on the mirror focal plane. The use of gas chambers with large active areas allows a sensitivity superior to existing experiments to be reached. Pad readout gives the required angular accuracy. The chamber is sensitive to the middle ultraviolet Cherenkov light produced by the showers in the atmosphere. Since the ozone in the upper atmosphere absorbs the direct ultraviolet light from any outer source, the lower level atmosphere provides a large dark volume in which the Cherenkov radiation from the showers can be isolated.

A new GeSi active target is presently used in the NA1 experiment at CERN to study photoproduction of charmed particles and to measure their lifetimes. Some general comments on the active target technique are made.

We present results of an R&D study for a specialized processor capable of precisely reconstructing, in pixel detectors, hundreds of charged-particle tracks from high-energy collisions at 40 MHz rate. We apply a highly parallel pattern-recognition algorithm, inspired by studies of the processing of visual images by the brain as it happens in nature, and describe in detail an efficient hardware implementation in high-speed, high-bandwidth FPGA devices. This is the first detailed demonstration of reconstruction of offline-quality tracks at 40 MHz and makes the device suitable for processing Large Hadron Collider events at the full crossing frequency.

A silicon strip vertex detector was designed, constructed and commissioned at the CDF experiment at the Tevatron collider at Fermilab. The mechanical design of the detector, its cooling and monitoring are presented. The front end electronics employing a custom VLSI chip, the readout electronics and various components of the SVX system are described. The system performance and the experience with the operation of the detector in the radiation environment are discussed. The device has been taking colliding beams data since May of 1992, performing at its best design specifications and enhancing the physics program of CDF.

The Silicon Vertex Tracker is the CDF online tracker which will reconstruct 2D tracks using hit positions measured by the Silicon Vertex Detector and Central Outer Chamber tracks found by the extremely Fast Tracker. The precision measurement of the track impact parameter will allow triggering on events containing B hadrons. This will allow the investigation of several important problems in B physics, like CP violation and Bs mixing, and to search for new heavy particles deca ying to bb.

A measurement of the lifetime of theΛ c baryon photoproduced coherently off a Germanium-Silicon target is presented. A signal ofΛ c →ΔK*→pKππ0 has been observed and the two different decay diagrams for this process are compared. A sample of 9Λ c decays gives a lifetime of 1.1 −0.4 +0.8 10−13 s.

This article describes a new charged-particle track fitting algorithm designed for use in high-speed electronics applications such as hardware-based triggers in high-energy physics experiments. Following a novel technique designed for fast electronics, the positions of the hits on the detector are transformed before being passed to a linearized track parameter fit. This transformation results in fitted track parameters with a very linear dependence on the hit positions. The approach is demonstrated in a representative detector geometry based on the CMS detector at the Large Hadron Collider. The fit is implemented in FPGA chips and optimized for track fitting throughput and obtains excellent track parameter performance. Such an algorithm is potentially useful in any high-speed track-fitting application.

The analog front-end for the Low Gain Avalanche Detector (LGAD) based precision timing application in the CMS Endcap Timing Layer (ETL) has been prototyped in a 65 nm CMOS mini-ASIC named ETROC0. Serving as the very first prototype of ETL readout chip (ETROC), ETROC0 aims to study and demonstrate the performance of the analog frontend, with the goal to achieve 40 to 50 ps time resolution per hit with LGAD (therefore reach about 30ps per track with two detector-layer hits per track). ETROC0 consists of preamplifier and discriminator stages, which amplifies the LGAD signal and generates digital pulses containing time of arrival and time over threshold information. This paper will focus on the design considerations that lead to the ETROC front-end architecture choice, the key design features of the building blocks, the methodology of using the LGAD simulation data to evaluate and optimize the front-end design. The ETROC0 prototype chips have been extensively tested using charge injection and the measured performance agrees well with simulation. The initial beam test results are also presented, with time resolution of around 33 ps observed from the preamplifier waveform analysis and around 41 ps from the discriminator pulses analysis. A subset of ETROC0 chips have also been tested to a total ionizing dose of 100 MRad with X-ray and no performance degradation been observed.

We present the results of a detailed simulation of the artificial retina pattern-recognition algorithm, designed to reconstruct events with hundreds of charged-particle tracks in pixel and silicon detectors at LHCb with LHC crossing frequency of 40 MHz. Performances of the artificial retina algorithm are assessed using the official Monte Carlo samples of the LHCb experiment. We found performances for the retina pattern-recognition algorithm comparable with the full LHCb reconstruction algorithm.

The silicon vertex trigger (SVT) in the CDF experiment at Fermilab performs fast and precise track finding and fitting at the second trigger level and has been a crucial element in data acquisition for Run II physics. However as luminosity rises, multiple interactions increase the complexity of events and thus the SVT processing time, reducing the amount of data CDF can record. The SVT upgrade aims to increase the SVT processing power to restore at high luminosity the original CDF DAQ capability. We describe the first steps in the SVT upgrade, consisting of a new associative memory with 4 times the number of patterns, and a new track fitter to take advantage of these patterns. We describe the system, its tests and its performance.

We present a device, based on the concept of associative memory for pattern recognition, dedicated to on-line track finding in high-energy physics experiments. A large pattern bank, describing all possible tracks, can be organized into Field Programmable Gate Arrays where all patterns are compared in parallel to data coming from the detector during readout. Patterns, recognized among 266 possible combinations, are output in a few 30 MHz clock cycles. Programmability results in a flexible, simple architecture and it allows to keep up smoothly with technology improvements.

One of the most challenging issues in the physics of the next few years is the study of the b-quark, via the detection of B-mesons and hadrons. The physical interest ranges from the measurement of the parameters in the Kobayashi-Maskawa matrix to that of CP violation in the neutral B-B system. Also, solving the problem of triggering and detecting B-mesons is a most effective way of approaching the problem of the detection of higher-mass heavy flavours. We describe here an R&D program, planned for the next two years, aimed at the study of a fast trigger system on beauty events, for both fixed target and collider experiments.

This paper describes the module of the drift chamber system used at CERN in a multiparticle magnetic spectrometer (FRAMM-NA1). Details are given about a new construction procedure which allows the quick and easy assembly of the chambers. Tests have been performed to check the construction accuracy, the detection efficiency and the final spatial resolutions, the results are reported. agger

The Online Silicon Vertex Tracker (SVT) is the trigger processor dedicated to the 2-D reconstruction of charged particle trajectories at the Level 2 of the CDF trigger. As the Tevatron luminosity rises, multiple interactions increase the complexity of events and thus the SVT processing time, reducing the amount of data CDF can record. The SVT upgrade aims to increase the SVT processing power to restore at high luminosity the original CDF Data Acquisition capability. In this paper we review the tracking algorithms implemented in the SVT and we report on the first step in the SVT upgrade.

In this paper we report simulation results of a study aiming to optimize parameters of a detector that uses low-gain avalanche detectors (LGAD) for high-precision timing measurements. The detector is assumed to be composed of a 50μm LGAD sensor coupled to front-end readout electronics which is used to measure the time of arrival of minimum ionizing particles. The simulation includes modeling of signal fluctuations in the LGAD sensor, variations of the analog bandwidth and signal-to-noise ratio (SNR) of the front-end electronics, time bin quantization, and radiation damage of the LGAD sensors. Two approaches to measure the timestamp are considered: leading edge and constant fraction. Simulated LGAD pulses before irradiation, and after irradiation with neutron fluences of 5×1014 n/cm2 and 1×1015 n/cm2, are studied. The time resolution for a 50μm LGADs was found to be 35 ps for front-end electronics bandwidths larger than 350 MHz and SNRs larger than 30. The time resolution at SNR of 30 for fluences of 5×1014 n/cm2 and 1×1015n/cm2 were found to be 31 ps and 37 ps, respectively.

We present the latest results of an R&D study for a specialized processor capable of reconstructing, in a silicon pixel detector, high-quality tracks from high-energy collision events at 40 MHz. The processor applies a highly parallel pattern-recognition algorithm inspired to quick detection of edges in mammals visual cortex. After a detailed study of a real-detector application, demonstrating that online reconstruction of offline-quality tracks is feasible at 40 MHz with sub-microsecond latency, we are implementing a prototype using common high-bandwidth FPGA devices.

We present the results of a test with a prototype apparatus aimed to detect the ultraviolet Cherenkov light in the wavelength range 2000–2300 Å, emitted by high energy cosmic ray showers. The system consists of a gas proportional chamber, with TMAE vapour as the photosensitive element, placed on the focal plane of a 1.5 m diameter parabolic mirror. The test was done during the summer of 1989 with cosmic ray showers seen in coincidence with the EAS-TOP experiment, an extended atmospheric shower charged particle array now being exploited at Campo Imperatore, 1900 m above sea level, on top of the Gran Sasso underground Laboratory of INFN. The results were positive and show that a full scale ultraviolet Cherenkov experiment with good sensitivity, angular resolution and virtually no background from moonlight or even daylight can be envisaged.

The mechanical design and construction progress of the CDF silicon vertex detector is described. Results on the location accuracy of the silicon strip detectors are presented and indicate an initial placement uncertainty of less than 10 μm. The water and gas cooling system, which is constructed of low mass materials and is used to remove heat from the readout electronics, is briefly described. Measurements of the performance of the silicon strip detectors are also given and show > 98.5% functioning strips for the assembled SVX detector.

D. Amidej d P. Azzi ', N. Bacchetta ', M. Bailey h, B. Barnett ', F. Bedeschi 9, D. Bisello 1, V. Bolognesi 9, C. Boswell 1, G. Busetto ', W.C. Carithers , H. Carter ', A. Castro S. Dell'Agnello 9, P.F. Derwent d, R. Ducar t A. Dunn d, R.P. Ely a, B. Flaugher S. Galeotti 9, A. Barbaro-Galtieri 1, A.F. Garfinkel h, C. Haber a,* *, S. Holland, M. Hrycyk b D. HerrUp b, R. Hughes ~, S. Kleinfelder , M. Loreti f, M. Mariotti ', J. Matthews ', A. Menzione 9, T. Merrick , C. Nelson b, L. Pescara f, N. Produit G. Punzi 11 F. Raffaelli 9, L. Ristori 11 0. Schneider 1, S . Segler b,, M.D . Shapiro N.M. Shaw h, T. ShaW b, j. Skarha ', F.R. Snider 1, T.Y. Song d, A. Spies , F. Tartarelli 9, b b P. Tipton ', S. Tkaczyk J. Tseng c, N. Turini 9, K. Turner S. Veicik c, G. Watts', T.R. Wesson b, W.C. Wester III ', H. Wenzel L', M. Wong , W. Yao ', F. Zetti 9 The University of California at Berkeley and Lawrence Berkeley Laboratory, Berkeley, California 94720, USA Fermi National Accelerator Laboratory, Bataria, Illinois 60510, USA c The Johns Hopkins University, Baltimore, Maryland 21218, USA d The University of Michigan, Ann Arbor, Michigan 48109, USA ' The University of New Mexico, Albuquerque, New Mexico 87131, USA f University of Padova, 1-35100 Padova Italy 11 Istituto Nazionale di Fisica Nucleare. and Universitv and Scuola Normale Superiore of Pisa, 1-56100 Asa, haly h Purdue University, West Lafayette, Indiana 47907, USA ' 7he University of Rochester, Rochester, New York 14627, USA

We describe the Monte Carlo simulation results of a trigger processor for high energy physics experiments. This processor performs on-line charged-track pattern recognition at full detector resolution. The simulation results are based on the measured performances of existing prototypes of the two building blocks of the trigger system.

We present a specialized processor dedicated to on-line track pattern recognition in high energy physics experiments. We describe the processor hardware architecture and the achieved performances. We also give some Monte Carlo results on more realistic working conditions.

The major reason for building a vertex detector for CDF is the tagging of decay vertices of particles with lifetime in the 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> 3/10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> 2 sec. range. This is a complementary approach to heavy flavour physics with respect to missing E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> and large P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> leptons. The method can be best applied to tag hadronic decays of heavy flavours, which have the largest branching ratios, but have eluded any specific tagging until now. It also works, although with somewhat reduced efficiency, in events with a semileptonic decay. All in all it promises to be a powerful tool in the search of rather elusive processes like Higgs, top, or fourth generation quark production [1]. The additional information provided by the vertex detector will also improve significantly the resolution of the CDF central tracking system [2].

A large Associative Memory system for on-line track reconstruction in a hadron collider experiment has been designed, prototyped and tested. This is the first such application of the Associative Memory concept and it is based on a full custom VLSI chip developed within this project. The Associative Memory is the heart of the Silicon Vertex Tracker, which is part of the Level 2 trigger of the CDF experiment, and is able to complete track finding in the CDF silicon vertex detector less then 1 /spl mu/sec after detector readout is over. This system is a multi-board project running on a common 30 MHz clock, but critical parts multiply clock frequency to operate up to 120 MHz. The Associative Memory board architecture, design, implementation and test are described. The main characteristics of this project are the use of sophisticated clock distribution techniques and the high density of components.

The Collider Detector at Fermilab (CDF) Silicon Vertex Tracker (SVT) is a device that works inside the CDF Level 2 trigger to find and fit tracks in real time using the central silicon vertex detector information. SVT starts from tracks found by the Level 1 central chamber fast trigger and adds the silicon information to compute transverse track parameters with offline quality in about 15μs. The CDF SVT is fully installed and functional and has been exercised with real data during the spring and summer 2001. It is a complex digital device of more than 100 VME boards that performs a dramatic data reduction (only about one event in a thousand is accepted by the trigger). Diagnosing rare failures poses a special challenge and SVT internal data flow is monitored by dedicated hardware and software. This paper briefly covers the SVT architecture and design and reports on the SVT building/commissioning experience (hardware and software) and on the first results from the initial running.

Multi-electrode germanium detectors are being used as an active target for decay path measurements of charmed mesons. The procedure used to fabricate such detectors is described and a brief analysis of their performance is given.

Real time pattern recognition is becoming a key issue in many position sensitive detector applications. The CDF collaboration is building SVT: a specialized electronic device designed to perform real time track reconstruction using the Silicon VerteX detector (SVX II). This will strongly improve the CDF capability of triggering on events containing b quarks, usually characterized by the presence of a secondary vertex. SVT is designed to reconstruct in real time charged particles trajectories using data coming from the silicon vertex detector and the central outer tracker drift chamber. The SVT architecture and algorithm have been specially tuned to minimize processing time without degrading parameter resolution.

Two of the biggest challenges for future HEP experiments at hadron colliders are triggering and track reconstruction of high-multiplicity events, where collisions have multiple primary vertices. The highly-non-linear scaling of computing power required for these tasks encourages the adoption of non-traditional, specialized architectures. Amongst them, the “artificial retina” approach, inspired by the architecture of the vision system in the living brain, promises large efficiency of hardware utilization, low-power and low-latency when implemented in state-of-art FPGA devices. The INFN-RETINA project has been a 3-year effort dedicated to investigate the potential of that approach in a real-time tracking processor at Level-0 of the LHC HEP experiments. We present results from studies performed on a prototype system capable of carrying out track reconstruction in a generic 6-layer silicon-strip detector with sub-μs latency at an event rate in excess of 30 MHz, and how a large-scale system can be implemented on multiple boards interconnected with high-speed optical links. Possible applications to real experimental environments will be also discussed.

The ETROC (Endcap Timing Readout Chip) is being developed for the LGAD-based CMS Endcap Timing Layer (ETL) at HL-LHC. The ETL on each side of the interaction region will be instrumented with a two-disk system of MIP-sensitive LGAD silicon devices to be read out by ETROCs for precision timing measurement with down to 30 ps timing resolution. The ETROC is designed to handle a 16 x 16 pixel cell matrix, with each pixel cell being 1.3 mm x 1.3 mm to match the LGAD sensor pixel size. Approximately 15% of the sensors near the highest eta region will experience hadron fluence above 1e15 neq/cm² towards end of operation of HL-LHC, resulting in small signal amplitude with LGAD gain reduced to around 10. For this reason, the front-end design for preamplifier and discriminator has been specifically optimized for the reduced LGAD signals, with enough flexibilities to meet the ETL specific needs for time resolution, power budget and radiation profile.

We present the results of an R&D study for a specialized processor capable of precisely reconstructing events with hundreds of charged-particle tracks in pixel and silicon strip detectors at 40 MHz, thus suitable for processing LHC events at the full crossing frequency. For this purpose we design and test a massively parallel pattern-recognition algorithm, inspired to the current understanding of the mechanisms adopted by the primary visual cortex of mammals in the early stages of visual-information processing. The detailed geometry and charged-particle's activity of a large tracking detector are simulated and used to assess the performance of the artificial retina algorithm. We find that high-quality tracking in large detectors is possible with sub-microsecond latencies when the algorithm is implemented in modern, high-speed, high-bandwidth FPGA devices.

We report on the R\&D for a first prototype of a silicon tracker based on an alternative approach for fast track finding. The working principle is inspired from neurobiology, in particular by the processing of visual images by the brain as it happens in nature. It is based on extensive parallelisation of data distribution and pattern recognition. In this work we present the design of a practical device that consists of a telescope based on single-sided silicon detectors; we describe the data acquisition system and the implementation of the track finding algorithms using available digital logic of commercial FPGA devices. Tracking performance and trigger capabilities of the device are discussed along with perspectives for future applications.

We report on the R\&D for a first prototype of a silicon tracker based on an alternative approach for fast track finding. The working principle is inspired from neurobiology, in particular by the processing of visual images by the brain as it happens in nature. It is based on extensive parallelisation of data distribution and pattern recognition. In this work we present the design of a practical device that consists of a telescope based on single-sided silicon detectors; we describe the data acquisition system and the implementation of the track finding algorithms using available digital logic of commercial FPGA devices. Tracking performance and trigger capabilities of the device are discussed along with perspectives for future applications.

The Online Silicon Vertex Tracker (SVT) is a new trigger processor dedicated to the 2-D reconstruction of charged particle trajectories at the level 2 of the CDF trigger. The SVT links the digitized pulse heights found within the Silicon Vertex Detector to the tracks reconstructed in the Central Outer Tracker by the level 1 Fast Track Finder. The SVT was recently modified in order to increase its efficiency. The new configuration uses all the Silicon Vertex detector layers. On the other hand the processing time has increased. This can be a problem at higher luminosities of the Tevatron. The "Road Warrior" is a new board that, eliminates redundant track candidates before the Track Fitting. It is based on the principle of the Associative Memory. The algorithm used is described in the paper, as well as the hardware implementation.

The Online Silicon Vertex Tracker (SVT) is a new trigger processor dedicated to the 2-D reconstruction of charged particle trajectories at Level 2 of the CDF trigger. The SVT links the digitized pulse heights found within the Silicon Vertex detector to the tracks reconstructed in the Central Outer Tracker by the Level 1 Fast Track finder. The SVT was recently modified in order to increase its efficiency. The new configuration uses all the Silicon Vertex detector layers. On the other hand the processing time has increased. This can be a problem at higher luminosities of the Tevatron. The "Road Warrior" is a new board that eliminates redundant track candidates before Track Fitting. It is based on the principle of the Associative Memory. The algorithm used is described in the paper, as well as the hardware implementation.

The goal of the INFN-RETINA R&D project is to develop and implement a computational methodology that allows to reconstruct events with a large number (> 100) of charged-particle tracks in pixel and silicon strip detectors at 40 MHz, thus matching the requirements for processing LHC events at the full bunch-crossing frequency. Our approach relies on a parallel pattern-recognition algorithm, dubbed artificial retina, inspired by the early stages of image processing by the brain. In order to demonstrate that a track-processing system based on this algorithm is feasible, we built a sizable prototype of a tracking processor tuned to 3 000 patterns, based on already existing readout boards equipped with Altera Stratix III FPGAs. The detailed geometry and charged-particle activity of a large tracking detector currently in operation are used to assess its performances. We report on the test results with such a prototype.

A measurement of the lifetime of D0-mesons photoproduced coherently off a germanium target is presented. Signals have been observed for the production of D0 into several channels and for D*+ → D0π+. A sample of 58 D0 decays gives a lifetime of (3.4−0.5+0.6 ± 0.3) · 10−13 s.

CDF II upgraded the calorimeter trigger to cope with the higher detector occupancy due to the increased Tevatron instantaneous luminosity (∼2.8×1032cm-2s-1). While the original system was implemented in custom hardware and provided to the L2 trigger a limited-quality jet clustering performed using a reduced resolution measurement of the transverse energy in the calorimeter trigger towers, the upgraded system provides offline-quality jet reconstruction of the full resolution calorimeter data. This allows to keep better under control the dependence of the trigger rates on the instantaneous luminosity and to improve the efficiency and purity of the trigger selections. The upgraded calorimeter trigger uses the general purpose VME board Pulsar, developed at CDF II and already widely used to upgrade the L2 tracking and L2 decision systems. A battery of Pulsars is used to merge and send the calorimeter data to the L2 CPUs, where software-implemented algorithms perform offline-like clustering. In this paper we review the design and the performance of the upgraded system.

We present the latest results on the prototype of a tracking processor capable of reconstructing events in a silicon-strip tracker at about 40 MHz event rate with sub-microsecond latency.The processor is based on an advanced pattern-recognition algorithm, called "artificial retina", inspired to the vision system of the mammals.We design and implement one of the first functional prototype of this processor on a DAQ board based on Alters Stratix III FPGAs.Then, in order to test the maximum rate capability, we port and optimize the processor on a high-speed board equipped with Altera Stratix V FPGAs.Future applications of this novel approach as real-time track trigger at LHC experiments are also discussed.

The Collider Detector at Fermilab collected a unique sample of jets originating from bottom-quark fragmentation ($b$-jets) by selecting online proton-antiproton ($p\overline{p}$) collisions with a vertex displaced from the $p\overline{p}$ interaction point, consistent with the decay of a bottom-quark hadron. This data set, collected at a center-of-mass energy of 1.96 TeV, and corresponding to an integrated luminosity of $5.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, is used to measure the $Z$-boson production cross section times branching ratio into $b\overline{b}$. The number of $Z\ensuremath{\rightarrow}b\overline{b}$ events is determined by fitting the dijet-mass distribution, while constraining the dominant $b$-jet background, originating from QCD multijet events, with data. The result, $\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}Z)\ifmmode\times\else\texttimes\fi{}\mathcal{B}(Z\ensuremath{\rightarrow}b\overline{b})=\phantom{\rule{0ex}{0ex}}1.11\ifmmode\pm\else\textpm\fi{}0.08(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.14(\mathrm{syst})\text{ }\text{ }\mathrm{nb}$, is the most precise measurement of this process, and is consistent with the standard-model prediction. The data set is also used to search for Higgs-boson production. No significant signal is expected in our data and the first upper limit on the cross section for the inclusive $p\overline{p}\ensuremath{\rightarrow}H\ensuremath{\rightarrow}b\overline{b}$ process at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ is set, corresponding to 33 times the expected standard-model cross section, or $\ensuremath{\sigma}=40.6\text{ }\text{ }\mathrm{pb}$, at the 95% confidence level.

Detectors with very high space resolution have been built in our laboratory and tested at CERN in order to investigate their possible use in high energy physics experiments. These detectors consist of thin layers of silicon crystals acting as ionization chambers. Thin electrodes, structured in strips or in more fancy shapes are applied to their surfaces by metal coating. The space resolution which could be reached is of the order of a few microns. An interesting feature of these solid state detectors is that they can work under very high or low external pressure or at very low temperature. The use of these detectors would strongly reduce the dimensions and the cost of high energy experiments.

We propose a method to identify b-quark jets at trigger level which exploits recently increased CDF trigger system capabilities. b-quark jets identification is of central interest for the CDF high-P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> physics program, and the possibility to select online b-jets enriched samples can extend the physics reaches especially for light Higgs boson searches where the Hrarrbb macr decay mode is dominant. Exploiting new trigger primitives provided by two recent trigger upgrades, the Level2 XFT stereo tracking and the improved Level2 cluster-finder, in conjunction with the existing Silicon Vertex Tracker (SVT), we design an online trigger algorithm aimed at selecting good purity b-jets samples useful for many physics measurements, the most important being inclusive Hrarr bb macr searches. We discuss the performances of the proposed b-tagging algorithm which must guarantee reasonable trigger rates at luminosity greater than 2times10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">32</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and provide high efficiency on Hrarrbb macr events.

The CDF Run II level-2 calorimeter trigger is implemented in hardware and is based on a simple algorithm used in Run I. This system has worked well for Run II at low luminosity. However, as the Tevatron instantaneous luminosity increases, the limitation due to the simple algorithm starts to become clear. In this paper, we will present an upgrade path to the level-2 calorimeter trigger system at CDF. This upgrade approach is based on the Pulsar board, a general purpose VME board developed at CDF and used for upgrading both the level-2 tracking and the Level-2 global decision crate. This paper will describe the design, hardware and software implementation, as well as the advantages of this approach over the existing system.

The trigger logic for the Collider Detector Facility (CDF) at Fermilab is described. An analog/digital system constructs triggers based on clusters of energy in the calorimetry. These triggers are then combined with signals from the muon and central tracking systems to make a global trigger. Two levels of trigger logic have been implemented: a 'Level 1' trigger which is dead-timeless, and a more sophisticated Level 2 trigger. The rejection factor provided by these two systems will be 103 - 104.

Four position sensitive silicon detectors have been tested inside the Tevatron beam pipe at Fermilab. The system is the prototype of the small angle silicon spectrometer designed to study primarily pp elastic and diffractive cross-sections at the Collider of Fermilab (CDF). Particles in the beam halo during p-p storage tests were used to study the performance of the detectors. Efficiency, linearity of response and spatial resolution are shown. Measurements performed at different distances from the beam axis have shown that the detectors could be operated at 8.5 mm from the beam with low rates and no disturbance to the circulating beams. This distance corresponds to about 11 times the standard half-width of the local beam envelope. The behaviour of the detectors with the radiation dose has also been investigated.

The SVT online tracker for the CDF upgrade reconstructs two-dimensional tracks using information from the Silicon Vertex detector (SVXII) and the Central Outer Tracker (COT). The SVT has an event rate of 100 kHz and a latency time of 10 /spl mu/s. The system is composed of 104 VME 9U digital boards (of 8 different types) and it is implemented as a data driven architecture. Each board runs on its own 30 MHz clock. Since the data output from the SVT (few Mbytes/sec) are a small fraction of the input data (200 Mbytes/sec), it is extremely difficult to track possible internal errors by using only the output stream. For this reason several diagnostic tools have been implemented: local error registers, error bits propagated through the data streams and the Spy Buffer system. Data flowing through each input and output stream of every board are continuously copied to memory banks named Spy Buffers which act as built in logic state analyzers hooked continuously to internal data streams. The contents of all buffers can be frozen at any time (e.g. on error detection) to take a snapshot of all data flowing through each SVT board. The Spy Buffers are coordinated at system level by the Spy Control Board. The architecture, design and implementation of this system are described.

The design is presented for a device presently being built to perform on line track finding and reconstruction for the CDF (Collider Detector at Fermilab) Silicon Vertex Detector (120 k channels). This device will provide track impact parameter information for the CDF Level 2 trigger decision, thus allowing CDF to trigger on events containing a long lived particle, in particular a b-quark. It will be the first device with such a capability installed at a proton-antiproton collider. The capability to separate b decays early in the trigger process is vital to the CDF program to collect a high statistic b sample to attack the study of CP violation in the b sector. Moreover SVT will open access to non-leptonic b decays like B/spl rarr//spl pi//spl pi/.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The online silicon vertex tracker (SVT) is composed of 104 VME 9U digital boards (of eight different types). Since the data output from the SVT (few MB/s) are a small fraction of the input data (200 MB/s), it is extremely difficult to track possible internal errors by using only the output stream. For this reason, several diagnostic tools have been implemented: local error registers, error bits propagated through the data streams, and the Spy Buffer system. Data flowing through each input and output stream of every board are continuously copied to memory banks named spy buffers, which act as built-in logic state analyzers hooked continuously to internal data streams. The contents of all buffers can be frozen at any time (e.g., on error detection) to take a snapshot of all data flowing through each SVT board. The spy buffers are coordinated at system level by the Spy Control Board. The architecture, design, and implementation of this system are described.

The final design and construction of a 46080 channel silicon microstrip vertex detector (SVX) for the Collider Detector Facility (CDF) experiment at the Tevatron collider are described. The system performance of the front end electronics employing a custom VLSI readout chip and the mechanical support and cooling systems for the 0.7 m/sup 2/ silicon detector are discussed. The authors present performance results from initial testing of individual components through final testing of the full system of detectors, readout, cooling, and data acquisition. Preliminary results from cosmic ray triggered data are also described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Technical details and methods used in constructing the Collision Detector Facility (CDF) silicon vertex detector are presented. Attention is given to the foam-carbon fiber composite structure used to support the silicon microstrip detectors and the procedure for achievement of 5- mu m detector alignment. The construction of the beryllium barrel structure, which houses the detector assemblies, is also described. In addition, the 10- mu m placement accuracy of the detectors in the barrel structure is discussed, and the detector cooling and mounting systems are described. The construction of the CDF silicon vertex detector has been completed. The silicon strip detectors are located to an accuracy of 10 mu m and >98-5% of the silicon strips are fully functional.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The CDF Run II Level-2 calorimeter trigger is implemented in hardware and is based on an algorithm used in Run I. This system insured good performance at low luminosity obtained during the Tevatron Run II. However, as the Tevatron instantaneous luminosity increases, the limitations of the current system due to the algorithm start to become clear. In this paper, we will present an upgrade of the Level-2 calorimeter trigger system at CDF. The upgrade is based on the Pulsar board, a general purpose VME board developed at CDF and used for upgrading both the Level-2 tracking and the Level-2 global decision crate. This paper will describe the design, hardware and software implementation, as well as the advantages of this approach over the existing system.

We present the results of an R&D study for a specialized processor capable of precisely reconstructing events with hundreds of charged-particle tracks in pixel and silicon strip detectors at $40\,\rm MHz$, thus suitable for processing LHC events at the full crossing frequency. For this purpose we design and test a massively parallel pattern-recognition algorithm, inspired to the current understanding of the mechanisms adopted by the primary visual cortex of mammals in the early stages of visual-information processing. The detailed geometry and charged-particle's activity of a large tracking detector are simulated and used to assess the performance of the artificial retina algorithm. We find that high-quality tracking in large detectors is possible with sub-microsecond latencies when the algorithm is implemented in modern, high-speed, high-bandwidth FPGA devices.

We present the design for the first prototype of a tracking system with “artificial retina” for fast track finding. The “artificial retina” is a tracking algorithm inspired by neurobiology and based on extensive parallelization of data distribution and pattern recognition. It allows track finding with a latency < 1 µs and with track parameter resolutions that are comparable with offline reconstruction results. This tracking system prototype consists of a telescope with 8 planes of single-sided strip detectors that are readout using custom ASICs providing hit position and pulse height. The “artificial retina” algorithm can be implemented using commercial FPGAs organized in three main blocks: a switch for the parallel distribution of the hits, a pool of processing units for the digital processing of the hits and pattern recognition, and a block for track parameter calculations. We will discuss the implementation of the “artificial retina” algorithm in the FPGAs, the performance of the device, and the perspectives for possible future applications.

We present the first prototype of a silicon tracker using the artificial retina algorithm for fast track finding. The algorithm is inspired by the neurobiological mechanism of recognition of edges in mammals visual cortex. It is based on extensive parallelization and is implemented on commercial FPGAs allowing us to reconstruct real time tracks with offline-like quality and <1μs latencies. The practical device consists of a telescope with 8 single-sided silicon strip sensors and custom DAQ boards equipped with Xilinx Kintex 7 FPGAs that perform the readout of the sensors and the track reconstruction in real time.

We present the first results of the prototype of a silicon tracker with trigger capabilities based on a novel approach for fast track finding. The working principle of the "artificial retina" is inspired by the processing of visual images by the brain and it is based on extensive parallelisation of data distribution and pattern recognition. The algorithm has been implemented in commercial FPGAs in three main logic modules: a switch for the routing of the detector hits, a pool of engines for the digital processing of the hits, and a block for the calculation of the track parameters. The architecture is fully pipelined and allows the reconstruction of real-time tracks with a latency less then 100 clock cycles, corresponding to 0.25 microsecond at 400 MHz clock. The silicon telescope consists of 8 layers of single-sided silicon strip detectors with 512 strips each. The detector size is about 10 cm × 10 cm and the strip pitch is 183 μm. The detectors are read out by the Beetle chip, a custom ASICs developed for LHCb, which provides the measurement of the hit position and pulse height of 128 channels. The "artificial retina" algorithm has been implemented on custom data acquisition boards based on FPGAs Xilinx Kintex 7 lx 160. The parameters of the tracks detected are finally transferred to host PC via USB 3.0. The boards manage the read-out ASICs and the sampling of the analog channels. The read-out is performed at 40 MHz on 4 channels for each ASIC that corresponds to a decoding of the telescope information at 1.1 MHz. We report on the first results of the fast tracking device and compare with simulations.

We report on the performances of a prototype for a specialized processor capable of reconstructing charged-particle tracks in a realistic Large Hadron Collider (LHC) detector, at full readout speed and with sub-microsecond latency. The processor is based on an innovative pattern recognition, called “artificial retina” algorithm, inspired by the vision system of the mammals. A prototype system has been designed, simulated, and implemented on readout boards equipped with Altera Stratix III FPGA devices. This is an important step towards the realization of a real-time track reconstruction device capable of processing complex events of high-luminosity LHC experiments at 40 MHz crossing rate.