Professor Brian Foster OBE, FRS

Abstract:

Rectangular drift chamber cells have been constructed and tested using an electron test beam facility at DESY. A systematic study of the time, spatial, energy and double track resolutions with a 100 MHz FADC readout is presented. The spatial resolution is 100 to 120 μm and the double track resolution is 2.5 mm with an Ar:C2H6 (50:50) gas mixture at atmospheric pressure. The dE dx resolution obtained corresponds to 6% resolution for a 72-layer chamber. © 1988.

Abstract:

The reaction e+e-→μ+μ- has been studied at centre of mass energies between 35.0 and 46.8 GeV using the TASSO detector at PETRA. We present measurements of the forward-backward charge asymmetry (Aμμ) and cross section σμμ for this reaction at three energies. At 35.0 GeV we obtain a cross section relative to the QED prediction of Rμμ=σμμ/σo=0.932±0.018±0.044 and Aμμ=(-10.6-2.3+2.2±0.5)%. At 38.3 GeV we find Rμμ=0.951±0.072-0.057+0.063 and Aμμ=(+1.7-8.6+8.5±0.5)%. At 43.6 GeV we measure Rμμ=0.921±0.037±0.055 and Aμμ=(-17.6-4.3+4.4±0.5)%. Our results are in good agreement with the predictions of the standard model. Including previous TASSO data we present improved determinations of muonic electroweak parameters. We also report on lower limits of possible contributions from contact interactions. © 1988 Springer-Verlag.

Abstract:

We have reconstructed 695 three-track τ decay vertices using a high resolution drift chamber close to the interaction point. From the distribution of decay lengths we measure the lifetime to be (3.06 ±0.20±0.14)×10−13 s. Using this result we find that the ratio of charged weak coupling constant for the τ to that of the μ, Gτ/Gμ=0.967±0.040 consistent with the concept of lepton universality. © 1988, Springer-Verlag. All rights reserved.

Abstract:

By seeking to identify magnetically charged particles by their trajectories in a magnetic field, we set limits on the production of monopoles and dyons, via the process e+e-→γ*→M {Mathematical expression}, of masses up to 17 GeV and of magnetic charges between 10 e and 70 e © 1988 Springer-Verlag.

Abstract:

We report on high statistics Bhabha scattering data taken with the TASSO experiment at PETRA at center of mass energies from 12 GeV to 46.8 GeV. We present an analysis in terms of electroweak parameters of the standard model, give limits on QED cut-off parameters and look for possible signs of compositeness. © 1988 Springer-Verlag.