121961325
Simulation of b-jet identification in a non-magnetic detector☆
Abstract The simulation of a silicon microstrip detector at the center of the D0 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 μm the gluon/b-jet rejection factor is estimated to be 25 for a b-jet efficiency of 25%. The detection of top quarks in the presence of background from high p 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. >
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.
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.
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.
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.
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].
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>>
119726162
First operation with a crystal septum to replace a magnet in a charged particle beam
Abstract Particle channeling in a bent crystal at Fermilab has been used to replace a magnet in a secondary charged particle beam. The maximum momentum of particles that could be transmitted to an experimental location was raised from the magnetic septum limit of 225 GeV/ c to the full primary beam momentum of 400 GeV/ c .
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.