Research and Development of the Positron Damping Rings for the Proposed International Linear Collider, and at CERN in Geneva, Switzerland for the Large Hadron Collider ATLAS Experiment\u27s Integrated Simulation Framework

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Research and Development of the Positron Damping Rings for the Proposed International Linear Collider and at CERN in Geneva, Switzerland for the Large Hadron Collider ATLAS Experiment\u27s Integrated Simulation Framwork

The topic of part I of my capstone is electron clouds, studied in the Cornell synchrotron accelerator. Electron clouds are an important phenomenon to study in circular particle accelerators such as the Large Hadron Collider (LHC), the Cornell synchrotron, and the damping ring for the proposed International Linear Collider (ILC). Low energy background electrons are normally present in high energy accelerators and are often not detrimental to beam performance, but certain operation conditions cause them to interact strongly with the beam, as was first observed in the 1980s in positron storage rings. The generation and amplification of the electron cloud is caused by ionization of residual gas in the vacuum chamber and irradiation of the chamber wall by synchrotron radiation. The Cornell CesrTA group researches the mitigation of the electron cloud in the Cornell synchrotron beam pipe by taking measurements of the cloud density and cloud effects on the beam. Various simulation programs are then used to try to study the physics behind cloud formation and beam quality at different cloud densities. The results presented here are from the ECLOUD program and concentrate on matching data from witness bunch scans that studied the relative cloud density at different bunch spacings to measure cloud decay over time. After many simulations runs, parameters were found for both 2.1 and 5.3 GeV of beam energy at 5 mA per bunch that successfully caused agreement between simulation and data. The values for these parameters will be given in the report. Upper and lower bounds were also found for the SEMAX parameter in the secondary energy distribution, and the secondary energy distribution was optimized to cause better agreement between peak shapes in the simulation and data. For part II, I will discuss particle simulation studies for the LHC ATLAS detector at CERN, in Geneva, Switzerland. By 2015, the ATLAS experiment will have surpassed the limits of the amount of data it can handle in a reasonable amount of time. Using Monte Carlo simulations to model particle interactions inside the detector is an increasingly complex and computationally intense task, but is vital for data analysis. This is in large part because the very small cross-sections for new physics signatures with respect to background processes need a large quantity of events for the simulation. The greatest portion of computing time is spent on the active and passive interactions with the detector material. Since ATLAS is the biggest particle detector in volume ever created and is packed with tiny complex circuits, doing this modeling in the very detailed full simulation Geant4 is not always feasible. Fatras, a fast track simulation engine of the ATLAS inner detector and muon system, is a way around this by parametrizing the calorimeter response. So far, Fatras’ agreement with Geant4 has been extremely promising and reduces the computing time by two orders of magnitude. In the report, hadronic interactions were studied in the inner detector for both Geant4 and Fatras using a Geant4 hadronic interaction processor. The number of child particles coming out of simulated particle decays and their particle types were looked at for each simulator, and first attempts at parametrizing the hadronic interactions inside the inner pixel layers and SCT for the ATLAS detector were made

The Proton Spin Structure Function G2P at Low Momentum Transfer

Over the past several decades Jefferson Lab National Accelerator Facility has proven to be extremely successful in its endeavor to study the polarized structure of nucleons. Measurements of these nucleon structure functions have proven to be powerful tools in testing and understanding a number of effective theories of QCD. The neutron spin structure functions, g1n and g2n, and the proton spin structure function, g1p, have been measured to very high precision over a wide kinematic range. However, the second proton structure function, g2p, remained largely unmeasured. The primary goal of Jefferson Lab Hall A experiment E08-027 was to perform an inclusive measurement of the proton g2 structure function for the first time in the low momentum transfer range of 0.01 \u3c Q2 \u3c 0.13 GeV2. The experiment acquired data at Jefferson Lab in Hall A during February - May of 2012. Experiment E08-027 utilized a polarized frozen NH3 target and a polarized electron beam to examine inclusive eP scattering in the resonance region. Dynamic Nuclear Polarization was used to drive proton target polarizations to upwards of 70% at 5T and 15% at 2.5T for high statistics measurements of the double spin asymmetry. Using a convolution of the Bosted/Christy model and data for the unpolarized cross section contribution, the spin structure function g2p was extracted for two low Q2 bins. Results for the moments of these structure functions find reasonable agreement with chiPT predictions

The synthesis and pharmacology of some novel excitatory amino acid analogues

Certain amino acids, notably L-glutamate and L-aspartate, are believed to fulfil a role as excitatory neurotransmitters in the mammalian Central Nervous System (CNS). Investigation has revealed the presence of three, and possibly a fourth, type of receptor for such neurotransmitters. These receptors have been named after the most potent and selective agonist of each; thus they are usually referred to as N-methyl-D-aspartate (A1), quisqualate (A2), kainate (A3) and 2-amino, 4-phosphono butyric acid (A4); the designations in brackets being that of the nomenclature of Fagg and Foster

Dependence of the open-closed field line boundary in Saturn's ionosphere on both the IMF and solar wind dynamic pressure:comparison with the UV auroral oval observed by the HST

We model the open magnetic field region in Saturn's southern polar ionosphere during two compression regions observed by the Cassini spacecraft upstream of Saturn in January 2004, and compare these with the auroral ovals observed simultaneously in ultraviolet images obtained by the Hubble Space Telescope. The modelling employs the paraboloid model of Saturn's magnetospheric magnetic field, whose parameters are varied according to the observed values of both the solar wind dynamic pressure and the interplanetary magnetic field (IMF) vector. It is shown that the open field area responds strongly to the IMF vector for both expanded and compressed magnetic models, corresponding to low and high dynamic pressure, respectively. It is also shown that the computed open field region agrees with the poleward boundary of the auroras as well as or better than those derived previously from a model in which only the variation of the IMF vector was taken into account. The results again support the hypothesis that the auroral oval at Saturn is associated with the open-closed field line boundary and hence with the solar wind interaction

Care as an alternative to killing? Reconceptualising veterinary end of life care for animals

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Palliative care is routinely offered to humans in the UK, while euthanasia remains illegal. The converse is true for nonhuman animals (henceforth animals). Indeed, euthanasia is widely accepted as the appropriate course of action for “suffering” animals, and for those whose behaviours or suspected ill health are thought to pose a threat to others. This article details examples of nonhuman death at a multi-faith ashram whose members vehemently oppose all forms of killing on religious grounds. Through exploring their efforts in palliative care for animals, and their emphasis on natural death as a means of respecting the sanctity of life, the practical, emotional and theoretical viability of caring for, instead of killing, other animals at the ends of their lives is considered. In the process, normative distinctions between different categories of animals, (including humans), and different approaches to end of life care (palliative care, euthanasia, natural death) are called into question. Indeed, paying mindful attention to the diverse ways in which individual animals are cared for as they die reveals the potential violence inherent in both palliative care leading to natural death, and euthanasia, blurring perceptions of good and bad death in both veterinary and human medicine

Cluster spacecraft observations of a ULF wave enhanced by Space Plasma Exploration by Active Radar (SPEAR)

Space Plasma Exploration by Active Radar (SPEAR) is a high-latitude ionospheric heating facility capable of exciting ULF waves on local magnetic field lines. We examine an interval from 1 February 2006 when SPEAR was transmitting a 1 Hz modulation signal with a 10 min on-off cycle. Ground magnetometer data indicated that SPEAR modulated currents in the local ionosphere at 1 Hz, and enhanced a natural field line resonance with a 10 min period. During this interval the Cluster spacecraft passed over the heater site. Signatures of the SPEAR-enhanced field line resonance were present in the magnetic field data measured by the magnetometer on-board Cluster-2. These are the first joint ground- and space-based detections of field line tagging by SPEAR