Leptonically Produced Multimuon Final States in Muon Scattering at 270 GEV.
This dissertation summarizes the multimuon data of Fermilab experiment E319. In particular, a search has been made for possible heavy lepton signals and for other non-hadronic sources of muon-induced multimuon events. Conventional explanations for such events are also discussed. The experiment employed 270 GeV tagged muons incident on a long iron-scintillator target/calorimeter which sampled the energy of the absorbed final-state hadrons. The scattered and produced muons propagated through a magnetic spectrometer made of toroidal iron magnets and wire spark chambers. Hodoscope counters and small-angle vetos formed the experimental triggers. A new analysis program MULTIMU was developed to reconstruct muon tracks. This was used to filter the 8.2 x 10('5) triggers down to about 1.6 x 10('4) multimuon candidates. These events were visually scanned resulting in a true multimuon event sample of 449 dimuons and 64 trimuons. Detailed checks established finding efficiencies of (70 (+OR-) 8) percent for dimuons and (89 (+OR-) 8) percent for trimuons giving rates per deep-inelastic scatter of (6.3 (+OR-) 0.6) x 10('-4) dimuons and (4.1 (+OR-) 0.4) x 10('-5) trimuons, uncorrected for produced muon acceptance. Monte Carlo methods were employed to model the most likely multimuon processes including associated charm production, (pi)/k decay, hadronic final state interactions and QED tridents. Rate estimates from these calculations as well as general characteristics of the data implied that charmed meson production dominated the dimuon sample with small contributions from other hadronic sources. Histograms of produced muon kinematics for data and Monte Carlo were compared and hadronic model calculations subtracted. The resulting tiny signals appear in reasonable agreement with Monte Carlo calculations of QED tridents. Using kinematic cuts to suppress both hadronic and electromagnetic processes leaves no statistically significant signal attributable to the weak production of heavy leptons. Upper limits derived from this process were consistent with the best published numbers. The much smaller trimuon sample was adequately explained by a roughly equal mixture of hadronic sources and trident production. A few very high transverse momentum produced muons remain unexplained.
- Pub Date:
- Physics: Elementary Particles and High Energy