117830203
Observation of Upsilon, Upsilon', and Upsilon'' at the Cornell electron Storage Ring
The UPSILON, UPSILON', and UPSILON'' states have been observed at the Cornell Electron Storage Ring as narrow peaks in sigma(e/sup +/e/sup -/ ..-->.. hadrons) versus beam energy. Data were collected during a run of 1000 nb/sup -1/, using the Columbia University--Stony Brook segmented NaI detector. The measured mass differences are M(UPSILON')-M(UPSILON)=559 +- 1( +- 3) MeV and M(UPSILON'')-M(UPSILON)=889 +- 1( +- 5) MeV, where the errors in parentheses represent systematic uncertainties. Preliminary values for the leptonic width ratios were also obtained.
120228621
Observation of the Transition $\Upsilon^\prime \to \Upsilon \pi^+ \pi^- \to e^+ e^- \pi^+ \pi^-$
121517669
Measurement of charged particle multiplicities associated with large transverse momentum photons in proton-proton collisions
Abstract We have measured the behaviour or charged-particle multiplicities as a function of the transverse momentum of photons produced at 90° in proton-proton collisions. The data were obtained at the CERN Intersecting Storage Rings (ISR) at a centre-of-mass energy of 53 GeV and cover the transverse momentum range 0 p ⊥ c . The total associated charge multiplicity increases with p ⊥ and most of the increase is found in a very wide cone opposite the detected photons. Partial multiplicities in the direction of the photons vary only slightly with p ⊥ . However, multiplicities at small angles with respect to the beams decrease sharply with increasing p ⊥ .
117089603
Measurements of the A2- and A2+ Mass Spectra
123104321
Measurement of small-angle elastic scattering of pions and protons by nuclei
Targets made of C, Al, Cu, Pb, and U were exposed to ${\ensuremath{\pi}}^{+}$, ${\ensuremath{\pi}}^{\ensuremath{-}}$, and proton beams of 9.92 and 19.85 GeV/c (for $p$-Pb only) at the Brookhaven AGS. A magnetic spectrometer with spark chambers was used to detect elastically scattered particles in the Coulomb-nuclear interference region (5-35 mrad). Differential cross sections are presented and compared with an optical model, taking full account of multiple scattering in the target.
126286321
Observation of the Upsilon''' at CESR
120063494
High precision limited streamer drift tubes
Abstract A tracking telescope employing six layers of Al drift tubes 50 cm long, with diameter d = 3 cm and wall thickness 500 μm, has been built and successfully operated with a 40% Ar-60% iC 4 H 10 gas mixture at atmospheric pressure. The tube cells, with a 100 μm thick CuBe wire strung along the axis, enter streamer mode operation at V = 4.6 kV, and feature full efficiency and local resolution of ≤60 μm.
52216370
Measuring propagation speed of Coulomb fields
The problem of gravity propagation has been subject of discussion for quite a long time: Newton, Laplace and, in relatively more modern times, Eddington pointed out that, if gravity propagated with finite velocity, planet motion around the sun would become unstable due to a torque originating from time lag of the gravitational interactions. Such an odd behavior can be found also in electromagnetism, when one computes the propagation of the electric fields generated by a set of uniformly moving charges. As a matter of fact the Liénard–Weichert retarded potential leads to the same formula as the one obtained assuming that the electric field propagate with infinite velocity. The Feynman explanation for this apparent paradox was based on the fact that uniform motions last indefinitely. To verify such an explanation, we performed an experiment to measure the time/space evolution of the electric field generated by an uniformly moving electron beam. The results we obtain, on a finite lifetime kinematical state, are compatible with an electric field rigidly carried by the beam itself.
110466342
Performance and Aging Studies of BaBar Resistive Plate Chambers
The BaBar detector is currently operating nearly 200 Resistive Plate Chambers (RPCs), constructed as part of an upgrade of the forward endcap muon detector in 2002. Although the average RPC efficiency remains high, numerous changes in the RPC performance (increased currents and rates) have been observed. A few of the highest rate RPCs have suffered efficiency losses of more than 15%. Several types of efficiency loss have been observed. Tests with humidified gas have shown that some of the lost efficiency is recoverable. However, efficiency losses in the highest rate regions have not yet improved with humid gases.
14377483
The RPC based IFR system at BaBar experiment: Preliminary results
Abstract The IFR system is a RPC-based detector used to identify muons and neutral hadrons in the BaBar experiment at PEP II machine in SLAC. The RPC system can be used to reconstruct the trajectory of muons, pions and neutral hadrons interacting in the iron of the IFR. The different range and hit pattern allow to discriminate different particles crossing the IFR. An overview of the system design and the preliminary results on the IFR performances are reported.
14677203
Study of Solid State Photon Detectors Read Out of Scintillator Tiles
We present preliminary results on efficiency and light collection uniformity read out performances of different assemblies of scintillator tiles, coupled with solid state photon detectors of different make. Our test beam data suggest that the use of 2 mm scintillator tiles without wavelength shifting fibers may be possible in an ILC hadron calorimeter.