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Ignition and steady state phases of Radio Frequency (RF) plasma in J-PARC ion source has been investigated by numerical modeling. The model takes into account the transport of plasma particles (electrons, protons, hydrogen molecular ions and cesium ions) in electromagnetic (EM) field with collision processes. Inductively coupled and capacitive EM fields are simultaneously solved in the model with plasma transport. Applying KEK parallel computation system A (64 cores, 56 nodes with 256 GB memory per node), behavior of high density plasma up to 1019 – 1020 m−3 in the steady state is calculated. In the simulation, it has been clarified that inductively coupled electric field in azimuthal direction and magnetic field in axial direction play a key role to maintain high density plasma which oscillates with frequency up to doubled value of applied RF frequency. The spatial distribution plot of plasma density and EM field at each phase may lead to understandings on how RF plasma is kept stable inside the source chamber.

We developed an electroformed copper lining for RF cavities. The pure copper lining with mirror-finish surface was produced by electropolishing the machined surface of an electroformed copper layer obtained from an acid copper sulfate bath containing no organic additives. The copper lining was successfully applied to large RF cavities for the Japan Hadron Facility being constructed by the High Energy Accelerator Research Organization. Dramatic rise in accelerating performance was achieved by this new lining.

Self-field loss of Ag/Bi-2223 tape conductors cooled by using the GM cryocooler in the temperature range of 60–100 K was studied in the conditions of various frequencies (10–500 Hz) of AC transport current. Self-field loss per cycle and per length divided by a square of critical current, Ic2, decreased with increase of the frequency and with decrease of temperature unlike Norris' equation. Especially, the loss reduction ratio by frequency change decreased with increase in temperature. To confirm difference in loss dependencies between the calculated and the experimental results, we also achieved the numerical analysis based on Maxwell's equations using a finite difference method. The analysis results were mostly in agreement with the experimental results.

Tohoku Electric Power Company and Tohoku University are cooperatively studying the effective use of a new monitoring .system using GPS (Global Positioning System). This system ensures achieving synchronous measurements at multiple remote electric supply station by using the time stamp facilities of GPS. First, this paper introduces briefly "Synchronous Monitoring System at multiple locations applying GPS techniques". Following section summarizes features of power flow fluctuation gotten by the developed monitoring system. The authors suggest some visual methodologies todisplay the features of the acquired data, and conduct a feasibility study on extracting hidden signals to identify insecure conditions in the power system.

A numerical model of plasma transport and electromagnetic field in the J-PARC (Japan Proton Accelerator Research Complex) radio frequency ion source has been developed to understand the relation between antenna coil heat loadings and plasma production/transport processes. From the calculation, the local plasma density increase is observed in the region close to the antenna coil. Electrons are magnetized by the magnetic field line with absolute magnetic flux density 30-120 Gauss which leads to high local ionization rate. The results suggest that modification of magnetic configuration can be made to reduce plasma heat flux onto the antenna.

In this paper, experimental results on the self excitation of induction generators have been investigated to obtain a secure and stable power generation. A micro power simulator which consists of a small-scale synchronous generator (0.5 kW) and a squirrel cage induction generator (0.4 kW) controlled by a servomotor and an equivalent LC network of the transmission line is successfully used to observe the self-excitation phenomena in the induction generators. The minimum rotor speed for the stable self-excitation has been measured for various load resistance. The slip characteristics corresponding to the loaded operation of the self-excitation can be associated with the saddle-node bifurcation of the nonlinear system dynamics for the induction generators. a close agreement is obtained between theoretical results and experimental results.

Two types of ARES cavities were tested in the TRISTAN accumulation ring in KEK. In this paper, results relating to the fundamental mode in the accelerating cavity are reported. The status of the cavity, including the detuning frequency under beam loading and the output power from the coupling cavity damper, was measured at different beam current and with various bunch patterns. Its behavior agrees well with the calculation based on a coupled resonator model.

The ARES (Accelerator Resonantly coupled with an Energy Storage) cavity, which consists of three cells, has been developed for the KEK B-Factory, and two types of the ARES cavity have been constructed for the beam test. Both the types were installed in the KEK TRISTAN Accumulation Ring and beam-tested. The accelerating cell of the ARES has a HOM-damped structure to lower the impedance of HOMs in order to store a high current beam. The spectra excited by the beam (single bunch, 100 mA) were measured for both the cavities with scanning of the resonant frequency. Basically these results are consistent with those of calculations. The HOMs appear to be damped as expected. But the actual spectra for three cells are more complicated than only the accelerating cell. During this experiment, however, any beam instabilities due to the impedance of the cavities were not observed. This paper describes only the "ARES95"-one of the two types of the ARES.

The coaxial (WX120D) antenna damper has been developed for damping the parasitic 0 and /spl pi/ modes of the KEKB ARES cavity. It is installed in the coupling cavity of the ARES. The damper consists of a disk-type coaxial ceramic window and a cross stub angle. The damper has a broadband RF property in order to absorb the RF power of the parasitic modes. The cross angle is utilized for supplying the cooling water to the antenna. The damper was designed by using a computer simulation code without a cold model test. Finally the properties of the damper has been confirmed by the high-power and the beam test for the ARES cavity.

Two types of sintered SiC (silicon carbide) ceramics have been developed and applied as the HOM absorbers for the second prototype ARES cavity (ARES96). One is bullet-shape SiC ceramics and the other is a tile one. The prototype cavity equipped with these absorbers was successfully tested with an electron beam in the TRISTAN accumulation ring. High power tests of these absorbers were carried out using an L-band RF power source. The HOM absorber designs and the results of the tests are discussed.

This paper describes a high-power test model of the normal conducting RF cavity for the KEK B Factory, KEKB. This cavity is loaded with a large coaxial waveguide for higher order mode (HOM) damping. The waveguide is equipped with a notch filter designed to block the TEM wave at the accelerating frequency of 509 MHz. Other waves coupled with the cavity HOMs are guided through the filter and absorbed by bullet-shape sintered SiC ceramics. This prototype model has been designed and built to demonstrate the performance in high power operation and the fabrication technologies involved. The results of the high-power test is reported together with the cavity structure and its RF properties.

QED processes up to O(α 4 ) have been studied at center-of-mass energies between 50 and 57 GeV using the AMY detector at TRISTAN. A possible substructure of the electron and muon is investigated in terms of chiral invariant contact interactions and also in terms of excited lepton production. The differential cross section data for e + e − →e + e − are consistent with the standard model at a confidence level of only 3.5%. From the absence of excited lepton production, we establish new upper limits on the coupling to excited electrons of mass up to 56 GeV/ c 2 and on the coupling to excited muons of mass up to 52 GeV/ c 2 .

The total cross section for e + e − annihilation into hadrons has been measured for CM energies ranging from 50 to 57 GeV. We fit the predictions of the standard model to these measurements and those at lower energies. The mass of the Z 0 boson, M Z , and the QCD scale parameter, Λ MS , are derived from the fit. The results are M Z =88.6 −1.8 +2.0 GeV/ c 2 , and Λ MS =0.15 −0.11 +0.16 GeV .

Multihadronic e/sup +/e/sup -/ annihilation events containing final-state leptons have been investigated with a 4.7-pb/sup -1/ data sample at c.m. energies of 50 and 52 GeV. The number of low-thrust events (Tless than or equal to0.8) with isolated leptons is consistent with the expectation of the standard model with five quark flavors. Limits on the production of new quarks and leptons are reported.

Identification of relativistic charged particles by means of fine sampling dE/dX measurements with a longitudinal drift chamber has been studied. Using a fast-sampling ADC (25 MHz), dE/dX was measured in a 1.4 mm gas thickness over an electron drift space of 51 mm. For the simulated 1 m long tracks of pions and electrons of 500 MeV/c, a particle separation of 10σ−12σ has been obtained, where σ is the r.m.s. resolution of the dE/dX measurement. This result with fine sampling is better by a factor of 1.7 compared to the dE/dX measurement with 21 mm sampling thickness. Further improvement achievable by reducing the correlation between neighbouring samples and simplification of electronics by use of the δ-ray clipping method are also discussed.

The R ratio for e/sup +/e/sup -/ annihilation into hadronic final states is measured to be 4.34 +- 0.45 +- 0.30 and 4.23 +- 0.20 +- 0.21 at c.m. energies of 50 and 52 GeV, respectively. From these values of R and an analysis of the event shapes we deduce a 95%-confidence-level upper limit for the production rate of new heavy charge +(2/3e or -(1/3e quarks to be 0.19 units of R.

A search for unstable heavy neutral leptons has been made at center-of-mass energies from 50 to 60.8 GeV with the AMY detector at the KEK Storage ring TRISTAN. The neutral leptons are assumed to decay via mixing to electrons and muons. Events with two leptons were searched for. No evidence for their existence was found. Limits in the mass range \ensuremath{\le}28.1 GeV/${c}^{2}$ and mixing-parameter range 9\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$\ensuremath{\le}\ensuremath{\Vert}${U}_{\mathrm{lL}}$${\ensuremath{\Vert}}^{2}$\ensuremath{\le}1 are presented for Dirac- and Majorana-type neutrinos.

Differential cross sections of proton Compton scattering have been measured in the energy range between 400 MeV and 1050 MeV at C.M.S. angles of 150° and 160°. The recoil proton was detected with a magnetic spectrometer using multi-wire proportional chambers and multi-wire spark chambers. The scattered photon was detected with a lead glass Cerenkov counter of the total absorptive type with two layers of multi-wire proportional chambers which measured the horizontal and vertical positions of the scattered photon. The proton Compton scattering was differentiated from the background of the π 0 photoproduction events with the use of angular correlations between the recoil proton and the scattered photon. The cross-section data show the clear second resonance peak at E γ = 750 MeV and a bump around E γ = 925 MeV at both angles. Also the angular distributions show the backward peak in the energy range between 700 MeV and 950 MeV. The data are compared with theoretical calculations based on an isobar model with some phases for the resonances. In this calculation, the proton Compton data were fitted varying the photocouplings of the nucleon resonances around the bump and the phases below the third resonances as free parameters. The calculation reproduced the angular distribution of differential cross sections well. However, it was inevitable that we use large photocouplings of P 33 (1600) in order to fit the bump.

We present evidence for the non-Abelian nature of QCD from a study of multijet events produced in ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilations from \ensuremath{\surd}s =50 to 57 GeV in the AMY detector at the KEK storage ring TRISTAN. A comparison of the three-jet event fraction at TRISTAN to the fraction of the DESY storage ring PETRA shows that the QCD coupling strength ${\ensuremath{\alpha}}_{s}$ decreases with increasing ${Q}^{2}$. In addition, measurements of the angular distributions of four-jet events show evidence for the triple-gluon vertex.

High-resolution spectroscopy of ..pi../sup +/ from K/sup -/ absorption at rest has been used for the first time to identify ..sigma../sup -/ hypernuclear states. The observed spectrum from a (CH)/sub n/ target has revealed a p/sub 3/2/-p/sub 1/2/ doublet of /sup 12/Be with narrow widths. The spin-orbit splitting of ..sigma../sup -/ is deduced to be 5 MeV, 0.8 times that for nucleons.

Measurements of the differential cross sections for e + e − →μ + μ − and e + e − →τ + τ − at values of s from 52 to 57 GeV are reported. The forward-backward asymmetries and the total cross sections for these reactions are found to be in agreement with predictions of the standard model of the electro-weak interactions. These measurements are used to extract values of the weak coupling constant g v e g v l and g A e g A l , where l = μ or τ .

A search for pair production for fourth-generation sequential leptons in e/sup +/e/sup -/ annihilation at a center-of-mass energy ..sqrt..s = 56 GeV is reported. Event topologies corresponding to the cases where one particle decays leptonically while the other decays hadronically as well as those where both particles decay hadronically were explored. We set a 95%-confidence-level lower limit of 27.6 GeV/c/sup 2/ for the mass of a fourth-generation lepton.

The radiative decay K/sup +/..--> mu../sup +/..nu gamma.. has been studied by a high-resolution magnetic spectrometer combined with a NaI(Tl) photon detector system. The momentum spectrum of muon from this decay mode was measured in the region 214.5