The BABAR Collaboration BABAR, the detector for the SLAC PEP-II asymmetric e + e − B Factory operating at the Υ (4S) resonance, was designed to allow comprehensive studies of CP -violation in B-meson decays. Charged particle tracks are measured in a multi-layer silicon vertex tracker surrounded by a cylindrical wire drift chamber. Electromagnetic showers from electrons and photons are detected in an array of CsI crystals located just inside the solenoidal coil of a superconducting magnet. Muons and neutral hadrons are identified by arrays of resistive plate chambers inserted into gaps in the steel flux return of the magnet. Charged hadrons are identified by dE/dx measurements in the tracking detectors and in a ring-imaging Cherenkov detector surrounding the drift chamber. The trigger, data acquisition and data-monitoring systems , VME-and network-based, are controlled by custom-designed online software. Details of the layout and performance of the detector components and their associated electronics and software are presented.

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carbon data, R = (1.042 ±0.020) -[1.04 ±0.91 (GeV/c 2 )~4]Q w 4 ,giving A + = <*> and A_ = 0.99 GeV/c 2 ; and A + > 1.06 and A_ >0.77 GeV/c 2 at the 95% confidence level.In conclusion, the results of this experiment are in agreement with the predictions of quantum electrodynamics as described by Bjorken, Drell, and Frautschi for the photoproduction of electron pairs.We would like to thank M. D. Rousseau for his invaluable contribution in the early stages of the experiment, and M. W. Collins and A. E. Groome for their excellent support throughout. We greatly appreciate the efforts of A. J. Egginton and the NINA machine group, and the help given by the technical services group under M. J. Moore. Finally, we acknowledge the encouragement and support of Professor A.Inelastic electron-proton scattering at high four-momentum transfer and large electron-energy loss has been used to investigate the electromagnetic structure and interactions of the proton. 1 We have measured the double differential cross section d 2 o{E,E', 6)/dQ,dE' for electrons on hydrogen in a new kinematic region made accessible by the Stanford linear accelerator. We report measurements made at 6° and 10° for several incident energies E, and for a range of scat-dan, and S. C. C. Ting, Phys. Rev. JL61, 1344(1967.