H. Sanders

A large air shower array to search for astrophysical sources emitting γ-rays with energies ≥1014 eV

We describe the technical details and the performance of a large array which detects both the electron and muon components in extensive air showers with energies ≥ 1014 eV. The array was designed to search for γ-rays from astrophysical sources. The background of cosmic rays is reduced by the selection of muon poor events. The array consists of 1089 scintillation detectors on the surface covering an area of 0.23 km2 and 1024 scintillation counters of 2.5 m2 each, buried 3 m below the surface for muon detection. Each of the surface detectors has its own local electronics and local data storage controlled by a microprocessor. The array is located at Dugway, Utah USA (40.2°N, 112.8°W) where the average atmospheric depth is 870 g/cm2.

SVT: an online silicon vertex tracker for the CDF upgrade

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 Two Level Fastbus Based Trigger System for CDF

Abstract We describe a two level FASTBUS based trigger processor designed and built for the CDF detector at the Fermilab p p 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.

CDF level 2 trigger upgrade

We describe the new CDF Level 2 Trigger, which was commissioned during Spring 2005. The upgrade was necessitated by several factors that included increased bandwidth requirements, in view of the growing instantaneous luminosity of the Tevatron, and the need for a more robust system, since the older system was reaching the limits of maintainability. The challenges in designing the new system were interfacing with many different upstream detector subsystems, processing larger volumes of data at higher speed, and minimizing the impact on running the CDF experiment during the system commissioning phase. To meet these challenges, the new system was designed around a general purpose motherboard, the PULSAR, which is instrumented with powerful FPGAs and modern SRAMs, and which uses mezzanine cards to interface with upstream detector components and an industry standard data link (S-LINK) within the system.

Silicon vertex tracker: a fast precise tracking trigger for CDF

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 b . In this report we describe the overall architecture, algorithms and the hardware implementation of the SVT.

The Timing system for the CDF electromagnetic calorimeters

We report on the design and performance of the electromagnetic calorimeter timing readout system (EMTiming) for the Collider Detector at Fermilab (CDF). The system will be used in searches for rare events with high-energy photons to verify that the photon is in time with the event collision, to reject cosmic-ray and beam-halo backgrounds, and to allow direct searches for new, heavy, long-lived neutral particles that decay to photons. The installation and commissioning of all 862 channels were completed in Fall 2004 as part of an upgrade to the Run II version of the detector. Using in situ data, including electrons from W ! en and Z ! ee decays, we measure the energy threshold for a time to be recorded to be 3:8 � 0:3 GeV ð1:9 � 0:1 GeVÞ in the central (plug) portion of the detector. Similarly, for the central (plug) portion we measure a timing resolution of 600 � 10 ps ð610 � 10 psÞ for electrons above 10 GeV (6 GeV). There are very few system pathologies such as recording a time when no energy is deposited, or recording a second, fake time for a single energy deposit. r 2006 Published by Elsevier B.V. PACS: 07.50.Qx; 29.40.Vj; 29.40.Mc

The CDF online silicon vertex tracker

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 B(s) 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.

First steps in the silicon vertex trigger upgrade at CDF

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

The CDF Silicon Vertex Tracker: Online precision tracking of the CDF Silicon Vertex Detector

SummaryThe 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.

Picosecond time-of-flight measurement for colliders using Cherenkov light

We propose to measure the velocity of particles produced at a hadron or lepton collider by measuring the time-of-flight in a finely segmented cylindrical geometry, in which the particles produce Cherenkov light while traversing the window of one element in an array of large-area (e.g. 5 cm /spl times/ 5 cm) multi-channel-plate photomultipliers (MCPs). There has been a substantial improvement in the time resolution of MCPs, which now have achieved a 10-psec transit-time spread (FWHM) for a single photon. We have simulated the Cherenkov emission and MCP response spectra for several commercially available MCPs, and find that a TOF resolution on the order of 1 psec should be attainable. This would allow /spl pi//K separation at 1/spl sigma/ up to a transverse momentum of /spl sime/ 25 GeV/C, in a detector such as CDF at the Fermilab Tevatron. It may also be possible to associate a photon with its production vertex by conversion directly in front of the MCP. The system we are considering requires a custom large-area MCP design with an anode consisting of impedance-matched segments, directly coupled to a circuit capable of psec resolution. Possible problems we know of so far are showering in the magnet coil that is in front of the system and stray magnetic field outside the coil. One last consideration is the cost, which will be comparable to other major detector subsystems.