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.
16901067
W Boson Physics at the Fermilab Tevatron
We present electroweak physics results from the D0 and CDF experiments using data from p \bar p collisions at \sqrt s = 1.8 TeV. Measurements of the cross sections times branching ratios for W and Z production, the inclusive width of the W boson and the W boson mass are presented. Direct tests of the WW\gamma and WWZ trilinear gauge boson couplings are also presented based on studies of diboson production.
122654690
Silicon microstrip wedge detectors for the DØ silicon tracker
Abstract The silicon tracking system proposed for the DO upgrade is discussed. The design of “wedge” modules for the forward disk section of the tracker is described. The wedge detectors are double-sided with a stereo angle of ± 15° and a strip pitch of 50 μm. Each strip includes an integrated ac-coupling capacitor and polysilicon bias resistor. First results from recently fabricated prototype wedge detectors are presented.
110541630
Punch-through currents and floating strip potentials in silicon detectors
Punch-through currents flowing between adjacent p/sup +/ strips on the surface of silicon microstrip drift detectors have been observed. Measurements of the floating strip potential have shown that a p/sup +/ strip acquires a voltage such that the punch-through current and the leakage current are equal and opposite. The factors influencing the threshold for the punch-through effect have been compared with a simple computer model, and the predicted variation with the interstrip gap is found to be in reasonable agreement with measured values for a variety of detectors. >
120475830
Physics capabilities of the DO upgrade detector
The D0 detector at Fermilab is being upgraded to meet the demands imposed by high luminosity Tevatron running planned to begin in 1998. The central tracking detectors will be replaced with silicon and scintillating fiber tracking systems inside a solenoidal magnetic field and a preshower detector will be added to aid in electron identification. The design and performance of these systems are described and detailed simulations of the physics capabilities of the upgraded detector are presented. In particular the authors focus on the study of electroweak boson properties and top quark physics and briefly describe the b-physics capabilities.
122003047
Silicon drift photodiodes
Abstract Low capacitance photodiodes based on the principle of the solid state drift chamber have been constructred and tested. The devices are based on a cellular design with an anode at the centre of each of five cells allowing electrons liberated by ionisation to drift up to 1 mm to the readout strip. Results on the performance of the detectors, including leakage current, capacitance and drift properties, are presented and compared with simulations. A second series drift photodiodes have been processed which incorporate improvements based on results acquired from the first design. They have leakage currents of a few nA and shorter drift times at the periphery of the drift cells. We present measurements showing the performance of the new devices.
108934738
Longitudinal beam dynamics with rf noise
The Dome-Krinsky-Wang (DKW) diffusion-in-action theory for rf-noise-induced emittance dilution is reviewed and related to recent work on the approximation of stochastic processes by Markov processes. An accurate and efficient numerical procedure is developed to integrate the diffusion equation of the DKW theory. Tracking simulations are undertaken to check the validity of the theory in the parameter range of the Superconducting Super Collider (SSC) and to provide additional information. The study of effects of rf noise is applied to two problems of interest at the SSC: (1) determination of noise tolerance levels in the rf system, and (2) feasibility of beam extraction using crystal channeling.
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.
122661247
The super fixed target beauty facility at the SSC
Abstract The rationale for pursuing beauty physics at the SSC in a fixed target configuration is described. The increased beauty production cross section at the SSC, combined with high interaction rate capability of the proposed detector, results in 10 10–11 produced BB events per year. The long decay length of the B hadrons (≌10 cm) allows direct observation of B decays in the high resolution silicon microstrip vertex detector. To optimize the operation of the proposed beauty spectrometer and the SSC, parasitic extraction of attendant or artificially generated large amplitude protons using crystal channeling is proposed and explored. The large sample of fully reconstructed B events allows detailed studies various CP violating decays with requisite statistics to confront the standard model. The CP physics potentials of the proposed experiment is evaluated and compared with alternative approaches, such as asymmetric e + e − B Factories and specialized hadron colliders.
121538444
Transformation of phase space densities under the coordinate changes of accelerator physics
In self-consistent modeling of many-particle systems it is convenient to solve the Maxwell equations for self-fields in coordinates based in the laboratory with time as the evolution variable, but conventional and also convenient to follow particle motion in Frenet-Serret coordinates referred to a reference orbit, with arclength along that orbit as the evolution variable. We refer to these two pictures as the laboratory system and beam system descriptions, while emphasizing that a Lorentz transformation is not involved; it is only a matter of two alternative descriptions of motion in one inertial frame. The problem then arises of how to express the laboratory system charge/current density for the Maxwell equations in terms of the phase space density described in the beam system. We find the exact expression, then make justified approximations to put the formula in a simple and practical form. Incidentally, we derive exact and approximate equations of motion in the different coordinates, without the use of the canonical formalism. The results have been applied in a study of coherent synchrotron radiation in bunch compressors.
10238716
From symplectic integrator to poincaré map: spline expansion of a map generator in Cartesian coordinates
Abstract Data from orbits of a symplectic integration can be interpolated so as to construct an approximation to the generating function of a Poincare map. The time required to compute an orbit of the symplectic map induced by the generator can be much less than the time to follow the same orbit by symplectic integration. The approximation has been constructed previously for full-turn maps of large particle accelerators, and a large saving in time (for instance a factor of 60) has been demonstrated. A shortcoming of our work to date arises from the use of canonical polar coordinates, which preclude map construction in small regions of phase space near coordinate singularities. Here, we show that Cartesian coordinates can be used, thus avoiding singularities. The generator is represented in a basis of tensor product B-splines. Under weak conditions, the spline expansion converges uniformly as the mesh is refined, approaching the generator of the Poincare map as defined by the symplectic integrator, in some parallelepiped of phase space centered at the origin.