124467838
Lorentz Invariance in tangent space
117052872
Normal coordinates in canonical form
5325226
A QUANTUM GOLDMAN BRACKET FOR LOOPS ON SURFACES
In the context of (2+1)–dimensional gravity, we use holonomies of constant connections which generate a q–deformed representation of the fundamental group to derive signed area phases which relate the quantum matrices assigned to homotopic loops. We use these features to determine a quantum Goldman bracket (commutator) for intersecting loops on surfaces, and discuss the resulting quantum geometry.
122698975
GROUP MANIFOLD DERIVATION OF CANONICAL THEORIES
The covariant canonical formalism previously developed supplemented by gauge fixing conditions leads naturally to corresponding component theories. We illustrate the method by deriving the “new variables” theory of Ashtekar, and the standard canonical tetrad theory. The method does not use the spinor formalism.
126036591
Lorentz invariance and the group manifold approach
120048132
Canonical normal coordinates
We examine the advantages and disadvantages of fixing the coordinate gauge to be that of the Riemann normal coordinates by applying the Dirac formalism for constrained canonical systems in general relativity.
115616794
Charmless semileptonic decays of B mesons
The authors have used the CLEO II detector at the CESR storage ring to study the endpoint region of the B-meson semileptonic momentum spectrum. Lepton production above the kinematic limit for b{r_arrow}cl{nu} is confirmed, although at a level which is smaller than has been observed previously. Model-dependent estimates os the ratio {vert_bar}V{sub ub}{vert_bar}/{vert_bar}V{sub cb}{vert_bar} will be reported.
122041574
Multi-pixel hybrid photodiode tubes for the CMS hadron calorimeter
Abstract Avalanche Photodiodes and 7-channel HPDs from DEP were installed on a prototype CMS HCAL and their response to muons, electrons and pions was measured in a test beam. DC response to a radioactive source used to calibrate the tiles was also studied. Increase in leakage current in the HPD from an integrated dose of 10 13 neutrons/cm 2 was observed using a Cf source.
16014194
The interaction of a giant planet with a disc with MHD turbulence - I. The initial turbulent disc models
This is the first of a series of papers aimed at developing and interpreting simulations of protoplanets interacting with turbulent accretion discs. In this first paper we study the turbulent disc models prior to the introduction of a perturbing protoplanet. We study cylindrical disc models in which a central domain is in Keplerian rotation and unstable to the magnetorotational instability. Models of varying disc size and aspect ratio H/r are considered with magnetic fields having zero net flux. We relate the properties of the turbulent models to classical viscous disc theory. All models were found to attain a turbulent state in their Keplerian domains with volume averaged stress parameter α ∼ 5 × 10 −3 . At any particular time the vertically and azimuthally averaged value exhibited large fluctuations in radius. However, an additional time average over periods exceeding three orbital periods at the outer boundary of the Keplerian domain resulted in a more smoothly varying quantity with radial variations within a factor of 2 or so. The vertically and azimuthally averaged radial velocity showed much larger spatial and temporal fluctuations, requiring additional time averaging for at least seven to eight orbital periods at the outer boundary of the Keplerian domain to limit them. Comparison with the value derived from the averaged stress using viscous disc theory yielded schematic agreement for feasible averaging times but with some indication that the effects of residual fluctuations remained. The behaviour described above must be borne in mind when considering laminar disc simulations with anomalous Navier‐Stokes viscosity. This is because the operation of a viscosity, as in classical viscous disc theory with anomalous viscosity coefficient, cannot apply to a turbulent disc undergoing rapid changes due to external perturbation. The classical theory can only be used to describe the time averaged behaviour of the parts of the disc that are in a statistically steady condition long enough for appropriate averaging to be carried out.
108864186
MINOS near-detector coil design
The 980-ton MINOS near detector will be installed in the new NuMI near hall at 100m below grade at Fermilab. It will be assembled from 282 1-inch thick steel plates. The planes are made from low carbon (1006), hot rolled steel and are toroidally magnetized. Each plane will be hung by two 'ears', which are extensions of the octagonal plane structure, similar to the hanging files in a file drawer. The plates have a center-to-center spacing of 5.94 cm. This document has been prepared for the 8/99 Conceptual Design Review of the MINOS near detector coil. It's main goal is to provide a set of references to previous documents and to assemble various design drawings and engineering calculations that have not been included in previous technical memos. It also provides some background material relevant for the coil implementation. Much of the text for this document is edited from the MINOS Detectors Technical Design Report.
120224392
The effects of neutron irradiation on multi-pixel hybrid photodiode tubes
Abstract The effects of neutron irradiation on a multi-pixel hybrid photodiode tube (HPD) were studied. The HPD underwent an integrated fluence of 10 13 neutrons cm 2 from a 252 Cf source. Increased leakage currents were observed during this irradiation, consistent with that observed from bare silicon detectors. The HPD was observed to be fully operational, with acceptable leakage currents, at the fluences expected during the lifetime of the CMS experiment. After the full dosage, small intrapixel inhomogeneities were observed in the HPD's response. The origins of these inhomogeneities and methods to mitigate the radiation damage were investigated.