The inclusive semileptonic branching ratios b —► e u X , uX , r vX and vX have been measured at LEP with a Supported by the German Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie b Supported by the Hungarian OTKA fund under contract number T 14459 c Supported also by the Comisión Interministerial de Ciencia y Technologia d Also supported by CONICET and Universidad Nacional de La Plata, CC 67, 1900 La Plata, Argentina e Also supported by Panjab University, Chandigarh-160014, India the L3 detector. The analysis is based on 2-jet hadronic Z decays obtained in the data collected between 1991 and 1992. Three separate event samples are analysed, contain­ ing electrons, muons and large missing energy (neutrinos), respectively. From the electron sample, we measure Br(b —> ez/X) (10.89±0.20=b0.51)% and, from the muon sam­ ple, Br(b —► ¡jl vX ) = (10.82±0.15±0.59)%, where the first error is statistical and the second is systematic. From

The two-photon collision reaction e+e~ e+e~/+/~ has been studied at y/s ~ 91 GeV using the L3 detector at LEP for / = e, (i, r. We have analysed untagged configurations where the two photons are quasi-real. Good agreement is found between our measurements and the ö ( a 4) QED expectation. © 1997 Elsevier Science B.V.

A search for exclusive decays of B[] and mesons has been performed in the channels ̂ J77, Bj —+ J77, Bj —» J7r° and Bs —► J7t°. The data sample consisted of more than three and half million hadronic Z decays collected by the L3 experiment at LEP from 1991 through 1995. No candidate events have been observed for any of the modes thus determining upper limits at 90% confidence level: 3.2 x 10~4 on Br(B^ -► J7r°) and the first experimental limits: Br(B° -+ J77) < 1.2 x 10\ Br(Bs -> J77) < 3.8 x 10“ 3, Br(B° -> h r°) < 1.2 x 10-3 .

A device for measuring total electron yields in the energy range 4-65 keV from conductor was set up successfully, which was made up of electron gun system, vacuum system and electrical system. By the pulse electron gun method, the total electron yields in the energy range 4-65 keV from silver were measured, based on the relation between the secondary electron yield and total electron yield at high incident electron energy from metals, the secondary electron yields in the energy range 10-65 keV from silver were deduced. Total electron yields measured with the device were compared with theoretical values, and the deduced secondary electron yield were compared with several authors' values, the results were discussed and a conclusion was drawn that the deduced secondary electron yields and the total electron yields from silver measured with the device are credible.

In the paper, design of a 2MeV electron linac is introduced, which includes calculation about parameters of the accelerator structure, longitudinal and transverse dynamics. This linac is used for sterilizing anthrax-bacilus in mails. Machine test shows that parameters of the accelerator can satisfy the design target.

In this paper, the microwave power system for HLS (Hefei Light Source) Linac is introduced. The power system includes five s-band 20MW klystrons and their modulators. In 2002, the klystron modulators and the control system were upgraded. Constant-current, switching power supplies were employed to replace the old conventional LC resonant charging facilities. The new system has run for four years and played an important role in the operation of the 200MeV Linac. A new soft xray FEL project (HTF) is now proposed in NSRL, the energy of electron beam will be increase from 200MeV to 800MeV. Seven s-band 80 MW klystrons and modulators will be employed as the new microwave power sources. The low energy spread specification of the Linac sets a stringent requirement to the stability of the klystron modulators. The paper also presents the technical considerations and preliminary design of the new system.

A numerical simulation method for coupler design is proposed. It is based on the matching procedure for the 2 pi/3 structure given by Dr. R. L. Kyhl. Microwave Studio EigenMode Solver is used for such numerical simulation. The simulation for a coupler has been finished with this method and the simulation data axe compared with experimental measurements. The results show that this numerical simulation method is feasible for coupler design.

This paper is intended to present the newly implemented wideband (100MHz) bunch oscillation measurement system, which is in nature a different method from the narrow-band (< 5MHz) facilities employed before. Basic formalism and implementation details of the system is introduced to illustrate the function of observing coupled bunch instabilities in time and frequency domain. The designed function includes detecting of transverse oscillation, synchrotron phase oscillation, as well as bunch filling pattern. Some diagnostics results of machine instabilities and application of this system are also discussed.

This paper derived the formulation for the real efficient emission coefficient of secondary electron under the condition that high energy primary electron incident on metal obliquely. It shows that the coefficient is reversely proportional to the cosine of the incident angle.

A new method is proposed for measurement of the length of pico-second electron bunch. For an electron bunch from MPG(Micro Pulse Gun), a numerical model using computing codes such as MAFIA has been constructed. And according to our own experimental condition, the model is discussed and its resolution is about 2ps. It is proved that the method is feasible for the measurement of the length of pico-second electron bunch.

A tracking algorithm using grid-based space charge fields is studied for the analysis of secondary emission microwave electron gun(SEMEG). The poisson equations of the space charge forces are determined in the hunch's rest frame with a multi-grid method. The particles' equations of motion are solved with a fifth-order embedded Runge-Kutta method. The results of the SEMEG by this algorithm are presented and compared with these by Mafia algorithm.

Due to the damping action during the magnetic moment precession, the magnetic flux generated by a pulsed magnetic field commonly will lag behind the field,so the phase of the pulsed magnetic field lags behind after it penetrates a coated metal. For the nonferromagnetic metal, the phaselag is very faint, and owing to the influence of conductor skin effect and eddy current, it can hardly be detected. An experimental method and the result obtained have been presented in this paper.In this method by using an ultrathin coating with zonal stripe to isolate and select an appropriate position to measure, thus the influences of conductor skin effect and eddy current have been reduced to a minimum. An analysis has been presented in this paper.

We present evidence for soft gluon interference, as required by QCD. This interference is expected to manifest itself in an angular ordering of the gluons radiated within a jet. Using hadronic decays of the Z boson in the L3 detector at LEP, we compare variables sensitive to such an angular ordering, namely the energy-energy correlation asymmetry and the newly introduced particle-particle correlation asymmetry, with the predictions of various parton shower models. Only those models which incorporate the expected interference agree with the data.

Eliminating or reducing thermal deformation of an accelerator structure (caused by microwave power dissipated on the walls of RF cavities) to insure resonance frequency is an important topic in the design of the structure. A civil accelerator for killing anthrax bacilli must be small and compact, and so must its cooling system. This paper introduces the design and optimization of a cooling structure for an 0.57 m long, 2 kW, disk-loaded waveguide accelerator structure, for which the temperature distribution is required to be 30 +/- 3degrees C. All the parameters have been calculated and optimized by means of FEM (the Finite Element Method). The simulation is accomplished with software called I-DEAS (Integrated Design, Engineering, Analysis System). An optimized structure with a jacket style cooling chamber has been designed. The outside wall of the jacket is made of stainless steel and its external diameter is phi118mm. The flux of the cooling water is as small as 0.45 ton/hour. As a result, the temperature nonuniformity of the accelerator tube is better than +/- 2.5degrees C. The system is also very robust against surrounding temperature shifts. The cooling system has been installed in a 2 MeV accelerator, and the facility is running well.

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Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible.

Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible.

Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible.

Ceramic chambers and ferrite kicker magnets were developed in HLS new injection system. The inner surfaces of the ceramic chambers were coated with 0.1 ohm/square metallic Mo layers to meet the requirements of both the penetration of pulse magnetic field and small beam coupling impedance. This paper presents the issues in fabricating these chambers and measurement of their loss factors and wake functions. Broadband impedance parameters of these ceramic chambers were obtained by fitting the measured data

We report measurements of the inclusive production of heavy quarkonium states in Z decays based on the analysis of 3.6 million hadronic events collected by the L3 detector at LEP. The measurement of inclusive J production and an improved 95% confidence level upper limit on gamma production are presented. In addition, two independent measurements of the ratio, f(p), Of prompt J mesons to those from B decay are made using two different isolation cuts to separate prompt J mesons from J mesons produced in the decays of b hadrons. The results are: Br(Z --> J + X) = (3.21 +/- 0.21 (stat.)(-0.28)(+0.19) (sys.)) X 10(-3) Br(Z --> gamma(1S) + X) < 4.4 x 10(-5), f(p) = (7.1 +/- 2.1 (stat.) +/- 1.2 (sys.)(-0.8)(+1.5) (theo.)) X 10(-2). (C) 1999 Published by Elsevier Science B.V. All rights reserved.