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.
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.
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. >
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.
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.
55222920
Simulations of the strong-strong beam-beam interaction in hadron colliders
We develop weighted macro-particle tracking and the Perron-Frobenius operator technique for simulating the time evolution of two beams coupled via the beam-beam interaction. The /spl pi/- and /spl sigma/-modes, with and without a sextupole perturbation, are studied based on the Vlasov-Poisson system. Extending the standard averaging formalism to maps with a small collective force, we derive an approximation to the "kick-rotate" model of our simulation. This eliminates the delta function smoothing in the Vlasov equation, common in many theoretical approaches. Action densities are quasi-equilibria, consistent with simulation, and linearization leads to uncoupled Fourier modes and third-kind integral equations. Extensions to 2-d.o.f. and a flexible general purpose code are being developed.
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.
40396751
Effect of RF phase noise on the SSC beam
The effect of white, low-pass, and notched RF phase noise on the SSC beam is investigated. The authors present and compare results from Monte-Carlo tracking simulations using a linear transfer map and from numerical solutions of an associated diffusion equation. Good agreement was found between simulation and Dome's theory on the diffusion process of the SSC beam due to RF phase noise. It is shown that the beam core is much less perturbed by low-pass and notched noise than by white noise.<<ETX>>
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.
122524960
Bunch coalescing studies for the SSC
It may become necessary to enhance the luminosity and increase the bunch spacing in the Superconducting Super Collider (SSC). Here we study the feasibility of bunch coalescing to achieve this. We choose the Medium Energy Booster (MEB) at extraction, momentum 200 GeV, to perform the operation. In order to properly align the bunches we propose to linearize the RF using the second and third harmonics. Theoretical studies with simulation are presented. The program ESME is used for the simulation.<<ETX>>