A Search for Rare Decay D0 --> mu+mu - High Energy Physics UPRM

··i2.2 Previous Searches for Rare Charm Decays 362.2.3 The Photoproduction E687 ExperimentProduction and decays of charm particles from high energy collisions with ahigh intensity photon beam and a beryllium target were studied by the Fermilab E687experiment [27] using a multiparticle spectrometer for particle identification and vertexingof charged hadrons and leptons.From the Tevatron beam, a photon beam frombremsstrahlung of secondary (Î*ϱÐ[†electrons “•”—– 350 ) hit a beryllium target. Chargedparticles were traced by four silicon microstrip detector stations. Those detectors werevery efficient for separating primary and secondary vertices. Charged particle momentumwas determined from deflections in two analysis magnets of opposite polarity with fivestations of multiwire proportional chambers. In order to identify electrons, pions, kaonsand protons, three multicell threshold Čerenkov counters were used.There were twoelectromagnetic calorimeters. Particles which passed the apertures of both magnets weredetected by the inner calorimeter which covered the forward solid angle. Those particlesthat only passed the first magnet were detected by the outer calorimeter covering the outerannular region. Two sections of thick steel muon filters divided four proportional tubeplanes which were used to identify muons in the forward solid angle [28].making three-track combinations of an event with the right particle identification. TheThe selection of candidates for De b Ñ?µe and De b € g e g started bycombination of the resulting three tracks were fit to a common secondary vertex.In order to detect muons with a momentum higher than › “ª”¢– , planes of scintillatormaterial in addition to four stations of proportional tubes, altogether known as the Muon