CDF Technical Overview

The CDF detector is undergoing a major upgrade from its Run I (1992-1995) configuration to prepare it for the next round of data taking (Run II), scheduled to begin in late 2000.  The result will be a detector which can handle the significant increase in data rate made possible by accelerator improvements.    We expect a factor of 20 times more data from the next running period than from the previous run.  This, along with fundamental improvements in our ability to select interesting events from the background of run-of-the-mill inelastic collisions in real time (within 20 microseconds), will result in an effective increase of factors of 100 to 1000 in the numbers of many interesting types of events.  This enormous increase in data presents an exceptional opportunity for new discoveries over the next few years.  Details regarding the detector upgrade can be found in the CDF II Technical Design Report.  

The upgrade to the detector is an important part of our group’s effort, and we have extensive responsibilities in this project.  We are designing and fabricating key elements of the trigger electronics using state-of-the-art computer-aided design tools from Mentor Graphics, Cadence and Xilinx, and making extensive use of programmable logic chips.  The trigger system is responsible for making decisions, in tens of microseconds, as to whether a particular event might be likely to be interesting for later analysis.  Due to the enormous number of uninteresting background events at a proton-antiproton collider, a system which effectively rejects these background events while maintaining most of those we wish to study is a critical component of the experiment.  

A second project we have undertaken is the upgrade to the precision tracking chamber (SVX II) which allows us to determine the trajectories of charged particles produced in a p-pbar collision to within approximately 10 microns.  This ability allows us to search for events which have a long-lived (1E-12 seconds is long for us) particle, by locating the decay products of this particle and finding that they appear to originate at a location separate from other particles in the event.  It is this signature which led to the discovery of the top quark, and makes all the b-sector measurements possible.  It is also true that many exotic particles (supersymmetric particles, leptoquarks, Higgs, etc)  have decay products which include a long-lived particle.  Precision tracking is a powerful tool for searching for these new particles.  The detector itself is made up of p-type silicon wafers with n-type implants, arranged in strips approximately 50 microns apart.  Charged particles traversing the wafer create electron-hole pairs in the semiconductor, which are collected at the implants, identifying the location of the charged particle.  The new detector has 5 layers of these detectors, each approximately 1 m long, with a total of 750,000 strips, each with its own amplifier and storage pipeline.  Our group is involved in the electronics system associated with reading out and recording the data from the detector.  This system has a highly parallel architecture using high-speed optical transmitters and receivers to achieve the throughput needed, with hundreds of components which must be made to work together smoothly.