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jB-meson decays to final states consisting of a D° or D* £ and one or two charged pions have been observed. The charged-B mass is 5270.8± 2.3 ±2.0 MeV and the neutral-E mass is 5274.2±1.9±2.0 MeV. PACS numbers: 14.40.Jz, 13.25.+m, 13.65. + iThe upsiion states 1 are interpreted as q-q resonances of a new quark, the b quark. The first three resonances are narrow, 2 ' 3 implying bound b flavor and a suppressed strong decay. The large width of the T(4S) resonance discovered at the e + e~ storage ring CESR 4 (Cornell Electron Storage Ring) and the observation that the decay products from the T(4S) include high-momentum leptons 5 imply that the T(4S) decays strongly into BB meson pairs, which then decay weakly. Until now, however, the b-flavored mesons themselves had not been found. Here we report that

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The apparatus used in the first direct measurement of energy spectra of positron annihilation-induced Auger electrons is described. The apparatus consists of a magnetically guided low-energy positron beam, a UHV surface preparation and characterization chamber, and an energy spectrometer. The spectrometer includes a trochoidal monochromator and a microchannel plate detector. A permanent magnet is mounted behind the sample to produce a field gradient which redirects the outgoing Auger electrons along the spectrometer axis. The combination of trochoidal monochromator and permanent magnet permits the measurement of the total kinetic energy of Auger electrons with an effective angular acceptance of ∼2π. The large angular acceptance and single particle detection capability of this spectrometer make it possible to perform Auger measurements using extremely low incident beam currents (∼10−15 A), and may make it useful in other low signal experiments. The spectrometer response function is modeled and compared to experimental results for different values of the magnetic field gradient.

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