UF PARTICIPATION IN CMS

A DETECTOR FOR THE LARGE HADRON COLLIDER (LHC) AT CERN

The focus of our research program is the development of detectors and techniques for the Compact Muon Solenoid (CMS) experiment. A total of 6 faculty in the High Energy Experiment Group (Professors Acosta, Avery, Konigsberg, Korytov, Mitselmakher, and Yelton) are pursuing CMS related research and Professors Field and Ramond are involved in the development of the CMS physics program. Contrary to its name, CMS is a huge detector designed to study proton collisions at the highest energies ever achieved: 14TeV (an energy 15,000 times greater than that of a proton at rest). It will begin operations in 2005 at the Large Hadron Collider (LHC), which is being constructed near Geneva, Switzerland at the European Center for Nuclear Research (CERN). The primary goal of this experiment is to understand the mechanism of electroweak symmetry breaking, either by detection of the scalar Higgs particle, which is predicted by the Standard Model of particle physics, or by discovering new interactions. Important secondary goals include the search for new symmetries and particles such as those arising from Supersymmetry---a theory that allows for the unification of the electromagnetic, weak, and strong force at very high energy by proposing that all known particles have partners with opposite spin statistics. A principal component of the CMS experimental program is the detection of muons, which can be identified by their deep penetration of matter. Muons, like electrons, are not influenced by the strong nuclear force---hence they are a clean probe of the hard scattering, isolated from any hadronic debris. Many channels through which new physics may arise involve muons, so a clear elucidation of these processes must involve muon detection. The High Energy Experiment Group at the University of Florida is heavily involved in all aspects of the muon detection system of the endcap regions of the CMS detector. Professor Mitselmakher is the overall project manager for this $35M system, coordinating the activities of about 80 U.S. physicists representing 12 Universities, Fermilab, and Lawrence Livermore National Lab. Professor Korytov is responsible for managing the development and production of the 468 Cathode Strip Chambers that will be built within this project. These 6-layer chambers will have a total of more than 2 million wires and about a half million readout channels. It will be the largest Multiwire Proportional Chamber system ever built by an order of magnitude covering total area of more than 1000m2. These chambers will detect muon particles with ~100um precision in space and ~5ns error in time. More than 100 of these chambers will be outfitted with electronics and tested in the High-Bay laboratory area of the University of Florida Physics Department. The LHC will provide nearly one billion collisions per second at design luminosity. The collisions occur when "bunches'' of protons circulating in opposite directions are brought into collision 40 million times per second. The experiment has the capacity to store only 100 of these crossings every second onto computer tape for further analysis. The rejection factor of 400,000 must be achieved in stages by a sophisticated electronic "trigger" that selects all collisions which are potentially interesting, but rejects those which originate from well understood mechanisms. Additionally, the trigger must keep up with the beam crossing frequency of 40 MHz so that events do not pileup in the system. These constraints require state-of-the-art high-speed electronic solutions, and pose an interesting challenge to the experimenter. In essence, the trigger must conduct a complex physics analysis in real-time at 40 MHz. Professor Acosta is responsible for the design and construction of a large portion of the Level 1 trigger for the endcap muon detection system of CMS. In particular, algorithms must be conceived and implemented to perform track finding in the endcap muon system---a pattern recognition problem of identifying penetrating muons in several detector stations amid a large flux of random coincidences. Specifically, the processor must compute the momentum of muon candidates from primitive detector information so that the experimenter can apply various thresholds. This is a $1.3M project beginning in 1998 at the University of Florida. Much of the development for CMS requires detailed simulations of the response of the various detectors to incoming particles produced in the collisions. The High Energy Group at the University of Florida can take advantage of 20 Gigaflops of supercomputer power (425 SpecFp95) distributed among 25 DEC Alpha workstations to accomplish much of the CPU-intensive simulation. Last Updated: December 9, 2000 | HEE Home | Comments & Suggestions