121294791
Background rates in silicon detectors used in uranium calorimeters
Abstract Ion-implanted silicon diode detectors have been used to establish counting rates from radioactive decays of uranium. The measurements allow the estimation of background counting rates in uranium-silicon calorimeters used in high energy physics experiments.
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. >
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. >
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.
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.
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.
14800784
A new model for the collective beam–beam interaction
The collective beam–beam interaction is studied in the framework of maps with a 'kick-lattice' model in the four-dimensional (4D) phase space of the transverse motion. A novel approach to the classical method of averaging is used to derive an approximate map which is equivalent to a flow within the averaging approximation. The flow equation is a continuous-time Vlasov equation which we call the averaged Vlasov equation (AVE), the new model of this paper. The power of this approach is evidenced by the fact that the AVE has exact equilibria and the associated linearized equations have uncoupled azimuthal Fourier modes. The equation for the Fourier modes leads to a Fredholm integral equation of the third kind and the setting is ready-made for the development of a weakly nonlinear theory to study the coupling of the π and σ modes. The π and σ eigenmodes are calculated from the third kind integral equation. These results are compared with the kick-lattice model using our weighted macroparticle tracking code and a newly developed, density tracking, parallel, Perron–Frobenius (PF) code.
117418480
Reliability of numerical solutions of a diffusion equation modeling rf noise-induced dilution in particle beams
The dilution process in particle beams caused by noise in the rf accelerating system has been modeled using a diffusion equation. Particle tracking can also be undertaken to determine the effects of rf noise, through it is much more computationally extensive than integrating the diffusion equation. In this paper we present the integration results using the Method of Lines (MOL) for certain important classes of noise. We will describe the numerical algorithms in detail, including those that are made to remove anomalous solutions. Reliability of the numerical results will be checked using both finite-difference and finite-element (Galerkin) methods in discretization and applying the same algorithms to the cases of linear and quadratic diffusion coefficients where exact solutions are known.
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.
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.
138551432
Proposal to improve the deflection of high energy particle beams by channeling in bent crystals of si and ge