54,010 research outputs found

    Phase shift keyed, pulse code modulated signal synchronizer

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    Signal is demodulated and synchronized by three loop circuits: ''Q'' loop uses quadrature signal to stabilize frequency; ''B'' loop acts on baseboard signal to stabilize phase; and decoding ''I'' loop acts on in-phase signal. Synchronizer may be used to eliminate false-lock

    A technique to eliminate false lock in PCM demodulation

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    One loop provides error signal which adjusts voltage controlled oscillator. Second loop multiplies input signal with generated in-phase signal. Both signals are integrated over bit period. First loop detects null which indicates lockup, and second loop emphasizes impact signal information

    Pulse code modulated signal synchronizer

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    A bit synchronizer for a split phase PCM transmission is reported that includes three loop circuits which receive incoming phase coded PCM signals. In the first loop, called a Q-loop, a generated, phase coded, PCM signal is multiplied with the incoming signals, and the frequency and phase of the generated signal are nulled to that of the incoming subcarrier signal. In the second loop, called a B-loop, a circuit multiplies a generated signal with incoming signals to null the phase of the generated signal in a bit phase locked relationship to the incoming signal. In a third loop, called the I-loop, a phase coded PCM signal is multiplied with the incoming signals for decoding the bit information from the PCM signal. A counter means is used for timing of the generated signals and timing of sample intervals for each bit period

    Hidden gauge structure and derivation of microcanonical ensemble theory of bosons from quantum principles

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    Microcanonical ensemble theory of bosons is derived from quantum mechanics by making use of a hidden gauge structure. The relative phase interaction associated with this gauge structure, described by the Pegg-Barnett formalism, is shown to lead to perfect decoherence in the thermodynamics limit and the principle of equal a priori probability, simultaneously.Comment: 10 page

    Formation of \eta'(958)-mesic nuclei and axial U_A(1) anomaly at finite density

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    We discuss the possibility to produce the bound states of the η(958)\eta'(958) meson in nuclei theoretically. We calculate the formation cross sections of the η\eta' bound states with the Green function method for (γ\gamma,p) reaction and discuss the experimental feasibility at photon facilities like SPring-8. We conclude that we can expect to observe resonance peaks in (γ\gamma,p) spectra for the formation of η\eta' bound states and we can deduce new information on η\eta' properties at finite density. These observations are believed to be essential to know the possible mass shift of η\eta' and deduce new information of the effective restoration of the chiral UA(1)U_A(1) anomaly in the nuclear medium.Comment: 4 pages, 3 figure

    Studies of parton distributions at a neutrino factory

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    The determination of parton distribution functions in the nucleon and nuclei is important for obtaining precise hadron-reaction cross sections, from which any new exotic signature could be found. We show that a future neutrino factory could provide important information on the parton distributions. First, a recent effort concerning the parametrization of nuclear parton distributions is explained. It suggests that the factory should be important for determining unknown behavior of valence-quark distributions in nuclei at small xx. Second, the facility could be used for understanding nucleon spin structure and isospin violation in the parton distributions.Comment: 1+3 pages, LaTeX2e, elsart.cls, wrapfig.sty, 1 eps figure. Talk given at the Third International Workshop on Neutrino Factories based on Muon Storage Rings (NuFACT'01), May 24 - 30, 2001, Tsukuba, Japan. To be published in proceedings. Email: [email protected], WWW: http://hs.phys.saga-u.ac.j

    Supersymmetric Particle Production at HERA

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    In the framework of the minimal supersymmetric standard model and the RR-parity breaking model, we investigate various production processes of the supersymmetric partner at HERA energies. Our emphasis is paid upon the scalar top quark, the partner of top quark, characterized by its lighter mass than the top quark and other scalar quarks in a model. We propose experimentally feasible approaches to search for clean signals of the stop from either its production or decay processes.Comment: 30 pages, LaTeX, 21 figures available upon reques

    Precision Measurement of Orthopositronium Decay Rate Using SiO_2 Powder

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    The intrinsic decay rate of orthopositronium formed in SiO2{\rm SiO_2} powder is measured using the direct 2γ2\gamma correction method such that the time dependence of the pick-off annihilation rate is precisely determined using high energy-resolution germanium detectors. As a systematic test, two different types of SiO2{\rm SiO_2} powder are used with consistent findings. The intrinsic decay rate of orthopositronium is found to be 7.0396±0.0012(stat.)±0.0011(sys.)μs17.0396\pm0.0012 (stat.)\pm0.0011 (sys.)\mu s^{-1}, which is consistent with previous measurements using SiO2{\rm SiO_2} powder with about twice the accuracy. Results agree well with a recent O(α2)O(\alpha^2) QED prediction, varying 3.85.63.8-5.6 experimental standard deviations from other measurements.Comment: 16 pages, 7 figures included. To be published in Physics Letters
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