51739637
EXISTENCE AND PROPERTIES OF AN EQUILIBRIUM STATE WITH BEAM-BEAM COLLISIONS
The equilbrium phase distribution of stored colliding electron beams is studied from the viewpoint of Vlasov-Fokker-Planck (VFP) theory. Numerical integration of the VFP system in one degree of freedom revealed a nearly Gaussian equilibrium with non-diagonal covariance matrix. This result is reproduced approximately in an analytic theory based on linearization of the beam-beam force. Analysis of an integral equation for the equilbrium distribution, without linearization, establishes the existence of a unique equilbrium at su ciently small current. The role of damping and quantum noise is clari ed through a new representation of the propagator of the linear Fokker-Planck equation with harmonic force. Presented at the 18th Advanced ICFA Beam Dynamics Workshop on Quantum Aspects of Beam Physics, Capri, Italy, Ocotber 15-20, 2000 To appear in proceedings published by World Scienti c, Singapore. Work supported in part by Department of Energy contracts DE-FG03-99ER41104 and DE-AC0376SF00515.
55035317
COMPARISON OF 1D AND 2D CSR MODELS WITH APPLICATION TO THE FERMI @ ELETTRA BUNCH COMPRESSORS
We compare our 2D mean field (Vlasov-Maxwell) treatment of coherent synchrotron radiation (CSR) effects with 1D approximations of the CSR force which are commonly implemented in CSR codes. In our model we track particles in 4D phase space and calculate 2D forces [1]. The major cost in our calculation is the computation of the 2D force. To speed up the computation and improve 1D models we also investigate approximations to our exact 2D force. As an application, we present numerical results for the Fermi{at}Elettra first bunch compressor with the configuration described in [1].
122076282
Deflection of GeV particle beams by channeling in bent crystal planes of constant curvature
189808711
Summary of Coherent Theory and Simulations Session
There were two types of talks which we attempt to summarize. Section 2 discusses the analytical talks and Section 3 the simulation talks. We hope that at least our summary will have the flavor of the session and serve as a reasonable pointer to papers in the proceedings and elsewhere. We take this opportunity to thank the participants of this session for making it an interesting one. The major emphasis in this session was on codes and we have tried to give an overview of basic computational strategies in Section 3 before highlighting the talks.
2396816
Progress on a Vlasov Treatment of Coherent Synchrotron Radiation from Arbitrary Planar Orbits
We report on our progress in the development of a fully self-consistent Vlasov treatment of coherent synchrotron radiation (CSR) effects on particle bunches traveling on arbitrary planar orbits. First we outline our Vlasov approach and the approximation we are currently studying. Then we discuss recent numerical results for a benchmark model studied extensively with codes by several authors.
15693839
Self-consistent computation of electromagnetic fields and phase space densities for particles on curved planar orbits
We discuss our progress on the self-consistent calculation of the 4D phase space density (PSD) and electromagnetic fields in a Vlasov-Maxwell formulation. We emphasize coherent synchrotron radiation (CSR) from arbitrary curved planar orbits, with shielding from the vacuum chamber, but space charge forces are naturally included. Our focus on the Vlasov equation will provide simulations with lower numerical/statistical noise than standard PIC methods, and will allow the study of issues such as emittance degradation and microbunching due to space charge and CSR in bunch compressors. The fields excited by the bunch are computed in the lab frame from a new double integral formula. The field formula is derived from retarded potentials by changes of variables. It is singularity-free and requires no computation of retarded times. Ultimately, the Vlasov equation will be integrated in beam frame coordinates using our method of local characteristics. As an important intermediate step, we have developed a "self-consistent Monte Carlo algorithm", and a corresponding parallel code. This gives an accurate representation of the source and will help in understanding the PSD support. In addition we have (1) studied carefully a 2D phase space Vlasov analogue and (2) derived an improved expression of the field of a 1D charge/current distribution which accounts for the interference of different bends and other effects usually neglected. Bunch compressors will be emphasized.
195840816
Tests Of The Radiation Hardness Of Vlsi Integrated Circuits And Silicon Strip Detectors For The SSC Under Neutron, Proton, And Gamma Irradiation
17092028
CP Violation Results from D0
We present results on CP violation from approximately 2.8 fb^{-1} of data collected by the D0 Experiment at the Fermilab Tevatron. The results presented are: (i) an improved measurement of the B_s^0 CP-violating phase from a flavor-tagged analysis of B_s^0 --> J/\psi \phi decays; (ii) a search for direct CP violation in B^{+-} --> J/\psi K^{+-} (\pi^{+-}) decays from a measurement of the charge asymmetry A_{CP}(B^{+-} --> J/\psi K^{+-}); and (iii) a search for indirect CP violation from searches for anomalous charge asymmetries in semileptonic B_s^0 decays.
125856023
Simulation of a silicon vertex detector in the D0 experiment
The simulation of a silicon microstrip detector at the center of the DO detector at the Fermilab Tevatron collider is described. The efficiency of a silicon vertex detector for identifying b-quark jets in a ``non-magnetic`` detector such as D0 is investigated. For a position resolution of 10 {mu}m the gluon/b-jet rejection factor is estimated to be 28 for a b-jet efficiency of 25%. The detection of top quarks in the presence of background from high p{sub T} W boson production is studied.
110084127
A silicon drift photodiode
A low-capacitance photodiode based on the principle of the solid-state drift chamber has been constructed and tested. The device is based on a cellular design with an anode at the center of each of five cells, allowing electrons liberated by ionization to drift up to 1 mm to the readout strip. Two designs were produced with p/sup +/ implant widths of 75 mu m and 85 mu m, respectively, using n-type material of 3.5-k Omega -cm resistivity. The opposite surface is a uniform p-type implant, features matching those of the other surface, and is unmetallized to ensure good photosensitivity. Results on the performance of the detector, including leakage current, capacitance, and drift properties, are presented and compared with simulation results. >
53491810
Searches for the Higgs Boson at the Tevatron
We report on direct searches for Higgs bosons carried out by the CDF and DO Collaborations in proton‐antiproton collisions at a center‐of‐mass energy of 1.96 TeV. Limits on the production cross section times branching fraction will be presented and a brief discussion of searches for supersymmetric Higgs bosons will be given. We will focus mainly on recent results only (those released in 2006), based on data sets of 260 – 950 fb−1 of data collected between 2004 – 2006.