An inclusive search for free quarks at PEP

Abstract We report the results of a search for fractionally charged particles in e + e − reactions at a center of mass energy of 29 GeV. We find no evidence for such particles and present upper limitts on R q = σ q q X/σ μμ for change 1 3 e and 2 3 e which range from 1 to 8 × 10 −2 for mass up to 12 GeV/ c 2

Search for fractionally charged particles in cosmic rays at large zenith angles

We have performed a single-particle search for fractional charge in cosmic rays having residual ranges at sea level >250 g/cm/sup 2/ concrete and zenith angles between 45/sup 0/ and 90/sup 0/. The detector is a hodoscope of 24 layers of plastic scintillator, eight layers of multiwire proportional chambers, and two layers of lucite Cherenkov counters. The acceptance of the instrument is 4.0 x 10/sup 3/ cm/sup 2/sr. An analysis of 3.5 x 10/sup 6/ triggers during a running time of 8 x 10/sup 5/ sec yields no particles with charge Q = (1/3) or Q = (2/3) and velocities greater than roughly-equal0.1c. We deduce an upper limit on the flux of fractionally charged particles of 8.5 x 10/sup -10/ (cm/sup 2/sr sec)/sup -1/ for relativistic Q = (1/3) and 7.6 x 10/sup -10/ (cm/sup 2/sr sec)/sup -1/ for Q = (2/3)

Test of the External Muon Identifier Efficiency

We wish to measure the EMI efficiency at hadron momenta higher than the 3 GeV used at the Beavatron. We propose to use the 30 M{sup 3} bubble chamber as the momentum and spatial analyzer of charged hadrons both of the incident beam and those final state hadrons of interactions that occur within the chamber. We would use the EMI modules as mounted on the bubble chamber vacuum tank to measure the efficiency of the EMI absorbers (coils and zinc) over a wide range of momenta. A hadron signature would be either the lack of a proportional chamber (pc) encoding within the '96% muon-circle' or a multiple PC encoding. We shall attempt to identify {pi}-{mu} decays in the chamber to use as a source of muons. Such a test would give us experience in spatially reconstructing tracks within the chamber and in projecting their trajectories out to the EMI detector modules. The early portion of this test could utilize whatever hadron beam the NAL bubble chamber group would be using at the time. We would make a copy of an adequate number of the original frames and compare the film quality with the original ones to test whether the EMI experiments of any sort, neutrinos or hadrons, could use copies rather than the original film negatives. The later portions of the test may require incident beams of momenta and particles of our choosing. Approximately 10{sup 4} interactions would be needed for the early test