Measurement of the charge asymmetry in beauty-dijet production at the LHCb experiment

A measurement of the charge asymmetry in beauty-dijet production at LHCb is presented in this thesis. The measurement uses the 2016 dataset of proton-proton collisions gathered by the detector, corresponding to an integrated luminosity of 1.7 fb-1. The charge asymmetry is measured in three bins of the invariant dijet mass, with bin edges at: [50, 75, 105, 150] GeV. This represents the first measurement of the charge asymmetry in beauty-dijet production in proton-proton collisions at a centre-of-mass energy of 13 TeV. To make the measurement a charge tagging method is first developed and tested in order to distinguish between the presence of b- and anti-b-quarks in jets. The calibration of simulated events is then carried out to correct for mismodelling when compared to the data. Next, fits are performed to extract the yield of beauty-dijets in the data sample. These yields are then corrected for detector and mistagging effects. The values of the asymmetry are then calculated. Results are compared to Standard Model predictions and are found to agree to within one standard deviation in all three bins.Open Acces

Navigation-by-music for pedestrians: an initial prototype and evaluation

Digital mobile music devices are phenomenally popular. The devices are becoming increasingly powerful with sophisticated interaction controls, powerful processors, vast onboard storage and network connectivity. While there are ‘obvious’ ways to exploit these advanced capabilities (such as wireless music download), here we consider a rather different application—pedestrian navigation. We report on a system (ONTRACK) that aims to guide listeners to their destinations by continuously adapting the spatial qualities of the music they are enjoying. Our field-trials indicate that even with a low-fidelity realisation of the concept, users can quite effectively navigate complicated routes

Thinking Outside the Box: An Interview with William Ferris

Interview

Creativity as a Cultural Value: An Interview with Bill Ivey

Interview

T-EBC coating system failure modes

The failure modes during steam cycling between 110 o and 1316oC of silicon-ytterbium silicate EBC systems applied to silicon carbide substrates have been investigated. Premature delamination failure at silicon-ytterbium monosilicate (YbMS) interfaces is shown to result from thermal expansion mismatch driven channel cracking of the YbMS layer. These coating penetrating cracks enabled water vapor and oxygen to reach the silicon bond coat layer outer surface from the start of the thermal cycling process, and resulted in the rapid growth of an upper (b-phase) cristobalite thermally grown oxide (TGO) layer on the silicon surface. This silica layer suffered rapid edge erosion followed by thermal contraction mismatch induced delamination crack extension from the edge of the samples during cooling. Replacement of the steam erosion resistant monosilicate by its dislicate counterpart eliminated the channel crack oxidizer pathways to the silicon surface and delayed the growth of the silica TGO. The eventual failure of this coating architecture was governed by the development of a significant delamination driving force at the silicon - ytterbium dislicate interface as the TGO thickness exceeded ~5 mm. Coating failure life was then governed by the rate of permeation of oxidants through the ytterbium dislicate and by the very large thermal stresses developed during the upper to lower cristobalite transformation. Interestingly, the oxidant permeation is likely to increase during prolonged cycling as the diffusion barrier dislicate layer thickness was decreased by steam erosion. Preliminary results from investigations of several concepts for extending the coating system life will be described. One sought to utilize a thermal barrier coating to reduce the EBC temperature and water vapor flow rate at the ytterbium dislicate outer surface. A second has investigated the use of thin hafnia layers applied to the silicon bond coat outer surface to induce the formation of a composite silica/hafnium silicate TGO to reduce the thermal strain energy for delamination. Please click Additional Files below to see the full abstract