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An optimised oscillation analysis of MINOS beam data

Description: This thesis presents results of the MINOS long baseline neutrino oscillation experiment. Charged Current interactions of {nu}{sub {mu}} from the NuMI beamline have been recorded in both the Near and Far Detectors between May 2005 and February 2006, corresponding to 1.27 x 10{sup 20} protons being delivered to the NuMI target. Several techniques for improving the sensitivity of an oscillation measurement are discussed and their impact assessed. 378 events are observed in the Far Detector during this period, compared to a prediction of 459 {+-} 31 events are observed in the Far Detector during this period, compared to a prediction of 459 {+-} 31 events when the observed Near Detector spectrum is extrapolated to the Far Detector over the 735 km baseline with no oscillations. In addition to this deficit of observed events, there is also evidence for spectral distortion in the Far Detector. A maximum likelihood analysis is used to determine the best fit point and allowed regions in {Delta}m{sup 2}{sub 23} and sin{sup 2}2{theta}{sub 23} parameter space. The best fit values for {Delta}m{sup 2}{sub 23} and sin{sup 2}2{theta}{sub 23} are found to be 2.55{sup +0.39}{sub -0.24} x 10{sup -3} eV{sup 2} and > 0.87 (68% CL) respectively.
Date: September 1, 2007
Creator: Culling, Andrew John & U., /Cambridge
Partner: UNT Libraries Government Documents Department

A study of atmospheric neutrino oscillations in the MINOS far detector

Description: In recent years, neutrino experiments have begun to challenge the Standard Model assumption that neutrinos are massless. There is now firm evidence that neutrinos undergo quantum mechanical oscillations between flavors. This would imply that neutrinos possess mass and that neutrino flavors are mixed by the weak interaction. Atmospheric neutrinos, produced by the interactions of cosmic rays in the earth's atmosphere, can be used to study these oscillations. The MINOS Far Detector has been collecting atmospheric neutrino data since 1st August 2003 using a 5.4 kT steel-scintillator sampling calorimeter located 700 m underground (2100 m water-equivalent) at the Soudan Underground Laboratory, Minnesota. The Far Detector is the first massive underground detector to possess a magnetic field. This makes the separation of atmospheric {nu}{sub {mu}} and {bar {nu}}{sub {mu}} charged current interactions possible for the first time. This thesis presents a study of atmospheric neutrino oscillations in the Far Detector, based on a total detector exposure of 316 days (3.3 kT-Yrs fiducial exposure). The separation of atmospheric neutrinos from the high background of cosmic muons is outlined. A total of 82 candidate events are observed, with an expectation of 109.9 {+-} 21.4 events in the absence of oscillations. Of the selected events, 40 events have a clearly identified charge, with 27 events tagged as neutrinos and 13 events tagged at anti-neutrinos. This represents the first direct observation of atmospheric {nu}{mu} and {bar {nu}}{sub {mu}} charged current interactions. A maximum likelihood analysis us used to determine the allowed region for the oscillation parameters {Delta}m{sub 23}{sup 2} and sin{sup 2}2{theta}{sub 23}. This disfavors the null oscillation hypothesis at the 79% confidence level. With the current low statistics, the sensitivity of the analysis is limited. The expected future sensitivity of the atmospheric neutrino analysis is discussed.
Date: August 1, 2005
Creator: Blake, Andrew & U., /Cambridge
Partner: UNT Libraries Government Documents Department

A study of muon neutrino disappearance with the MINOS detectors and the NuMI neutrino beam

Description: This thesis presents the results of an analysis of {nu}{sub {mu}} disappearance with the MINOS experiment, which studies the neutrino beam produced by the NuMI facility at Fermi National Accelerator Laboratory. The rates and energy spectra of charged current {nu}{sub {mu}} interactions are measured in two similar detectors, located at distances of 1 km and 735 km along the NuMI beamline. The Near Detector provides accurate measurements of the initial beam composition and energy, while the Far Detector is sensitive to the effects of neutrino oscillations. The analysis uses data collected between May 2005 and March 2007, corresponding to an exposure of 2.5 x 10{sup 20} protons on target. As part of the analysis, sophisticated software was developed to identify muon tracks in the detectors and to reconstruct muon kinematics. Events with reconstructed tracks were then analyzed using a multivariate technique to efficiently isolate a pure sample of charged current {nu}{sub {mu}} events. An extrapolation method was also developed, which produces accurate predictions of the Far Detector neutrino energy spectrum, based on data collected at the Near Detector. Finally, several techniques to improve the sensitivity of an oscillation measurement were implemented, and a full study of the systematic uncertainties was performed. Extrapolating from observations at the Near Detector, 733 {+-} 29 Far Detector events were expected in the absence of oscillations, but only 563 events were observed. This deficit in event rate corresponds to a significance of 4.3 standard deviations. The deficit is energy dependent and clear distortion of the Far Detector energy spectrum is observed. A maximum likelihood analysis, which fully accounts for systematic uncertainties, is used to determine the allowed regions for the oscillation parameters and identifies the best fit values as {Delta}m{sub 32}{sup 2} = 2.29{sub -0.14}{sup +0.14} x 10{sup -3} eV{sup 2} and sin{sup 2} 2{theta}{sub ...
Date: June 1, 2008
Creator: Marshall, John Stuart & U., /Cambridge
Partner: UNT Libraries Government Documents Department

Atmospheric neutrino observations in the MINOS far detector

Description: This thesis presents the results of atmospheric neutrino observations from a 12.23 ktyr exposure of the 5.42 kt MINOS Far Detector between 1st August 2003 until 1st March 2006. The separation of atmospheric neutrino events from the large background of cosmic muon events is discussed. A total of 277 candidate contained vertex {nu}/{bar {nu}}{sub {mu}} CC data events are observed, with an expectation of 354.4{+-}47.4 events in the absence of neutrino oscillations. A total of 182 events have clearly identified directions, 77 data events are identified as upward going, 105 data events are identified as downward going. The ratio between the measured and expected up/down ratio is: R{sup data}{sub u/d}/R{sup MC}{sub u/d} = 0.72{sup +0.13}{sub -0.11}(stat.){+-} 0.04 (sys.). This is 2.1{sigma} away from the expectation for no oscillations. A total of 167 data events have clearly identified charge, 112 are identified as {nu}{sub {mu}} events, 55 are identified as {bar {nu}}{sub {mu}} events. This is the largest sample of charge-separated contained-vertex atmospheric neutrino interactions so far observed. The ratio between the measured and expected {bar {nu}}{sub {mu}}/{nu}{sub {mu}} ratio is: R{sup data}{sub {bar {nu}}{nu}} / R{sup MC}{sub {bar {nu}}{nu}} = 0.93 {sup +0.19}{sub -0.15} (stat.) {+-} 0.12 (sys.). This is consistent with {nu}{sub {mu}} and {bar {nu}}{sub {mu}} having the same oscillation parameters. Bayesian methods were used to generate a log(L/E) value for each event. A maximum likelihood analysis is used to determine the allowed regions for the oscillation parameters {Delta}m{sub 32}{sup 2} and sin{sup 2}2{theta}{sub 23}. The likelihood function uses the uncertainty in log(L/E) to bin events in order to extract as much information from the data as possible. This fit rejects the null oscillations hypothesis at the 98% confidence level. A fit to independent {nu}{sub {mu}} and {bar {nu}}{sub {mu}} oscillation assuming maximal mixing for both is also ...
Date: September 1, 2007
Creator: Chapman, John Derek & U., /Cambridge
Partner: UNT Libraries Government Documents Department

Atmospheric Neutrinos in the MINOS Far Detector

Description: The phenomenon of flavour oscillations of neutrinos created in the atmosphere was first reported by the Super-Kamiokande collaboration in 1998 and since then has been confirmed by Soudan 2 and MACRO. The MINOS Far Detector is the first magnetized neutrino detector able to study atmospheric neutrino oscillations. Although it was designed to detect neutrinos from the NuMI beam, it provides a unique opportunity to measure the oscillation parameters for neutrinos and anti-neutrinos independently. The MINOS Far Detector was completed in August 2003 and since then has collected 2.52 kton-years of atmospheric data. Atmospheric neutrino interactions contained within the volume of the detector are separated from the dominant background from cosmic ray muons. Thirty seven events are selected with an estimated background contamination of less than 10%. Using the detector's magnetic field, 17 neutrino events and 6 anti-neutrino events are identified, 14 events have ambiguous charge. The neutrino oscillation parameters for {nu}{sub {mu}} and {bar {nu}}{sub {mu}} are studied using a maximum likelihood analysis. The measurement does not place constraining limits on the neutrino oscillation parameters due to the limited statistics of the data set analysed. However, this thesis represents the first observation of charge separated atmospheric neutrino interactions. It also details the techniques developed to perform atmospheric neutrino analyses in the MINOS Far Detector.
Date: December 1, 2004
Creator: Howcroft, Caius L.F. & U., /Cambridge
Partner: UNT Libraries Government Documents Department

MINOS+: a Proposal to FNAL to run MINOS with the medium energy NuMI beam

Description: This is a proposal to continue to expose the two MINOS detectors to the NuMI muon neutrino beam for three years starting in 2013. The medium energy setting of the NuMI beam projected for NO{nu}A will deliver about 18 x 10{sup 20} protons-on-target during the first three years of operation. This will allow the MINOS Far Detector to collect more than 10,000 charged current muon neutrino events in the 4-10 GeV energy range and provide a stringent test for non-standard neutrino interactions, sterile neutrinos, extra dimensions, neutrino time-of-flight, and perhaps more. In addition there will be more than 3,000 neutral current events which will be particularly useful in extending the sterile neutrino search range.
Date: May 1, 2011
Creator: Tzanankos, G.; U., /Athens; Bishai, M.; Diwan, M.; /Brookhaven; Escobar, C.O. et al.
Partner: UNT Libraries Government Documents Department

Observation in the MINOS far detector of the shadowing of cosmic rays by the sun and moon

Description: The shadowing of cosmic ray primaries by the the moon and sun was observed by the MINOS far detector at a depth of 2070 mwe using 83.54 million cosmic ray muons accumulated over 1857.91 live-days. The shadow of the moon was detected at the 5.6 {sigma} level and the shadow of the sun at the 3.8 {sigma} level using a log-likelihood search in celestial coordinates. The moon shadow was used to quantify the absolute astrophysical pointing of the detector to be 0.17 {+-} 0.12{sup o}. Hints of Interplanetary Magnetic Field effects were observed in both the sun and moon shadow.
Date: August 1, 2010
Creator: Adamson, P.; /Fermilab; Andreopoulos, C.; U., /Rutherford /Athens; Ayres, D.S.; /Argonne et al.
Partner: UNT Libraries Government Documents Department

A Search for Lorentz Invariance and CPT Violation with the MINOS Far Detector

Description: We searched for a sidereal modulation in the MINOS far detector neutrino rate. Such a signal would be a consequence of Lorentz and CPT violation as described by the Standard-Model Extension framework. It also would be the first detection of a perturbative effect to conventional neutrino mass oscillations. We found no evidence for this sidereal signature and the upper limits placed on the magnitudes of the Lorentz and CPT violating coefficients describing the theory are an improvement by factors of 20-510 over the current best limits found using the MINOS near detector.
Date: July 1, 2010
Creator: Adamson, P.; /Fermilab; Auty, D.J.; U., /Sussex; Ayres, D.S.; /Argonne et al.
Partner: UNT Libraries Government Documents Department

Resolution of a High Performance Cavity Beam Positron Monitor System

Description: International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved--ideally using beam-based stability measurements. It has been estimated that RF cavity beam position monitors (BPMs) could provide position measurement resolutions of less than one nanometer and could form the basis of the desired beam-based stability measurement. We have developed a high resolution RF cavity BPM system. A triplet of these BPMs has been installed in the extraction line of the KEK Accelerator Test Facility (ATF) for testing with its ultra-low emittance beam. A metrology system for the three BPMs was recently installed. This system employed optical encoders to measure each BPM's position and orientation relative to a zero-coefficient of thermal expansion carbon fiber frame and has demonstrated that the three BPMs behave as a rigid-body to less than 5 nm. To date, we have demonstrated a BPM resolution of less than 20 nm over a dynamic range of +/- 20 microns.
Date: July 6, 2007
Creator: Walston, S.; Chung, C.; Fitsos, P.; Gronberg, J.; /LLNL, Livermore; Ross, M. et al.
Partner: UNT Libraries Government Documents Department

Supernova / Acceleration Probe: a Satellite Experiment to Study the Nature of the Dark Energy

Description: The Supernova/Acceleration Probe (SNAP) is a proposed space-based experiment designed to study the dark energy and alternative explanations of the acceleration of the Universe's expansion by performing a series of complementary systematics-controlled astrophysical measurements. We here describe a self-consistent reference mission design that can accomplish this goal with the two leading measurement approaches being the Type Ia supernova Hubble diagram and a wide-area weak gravitational lensing survey. This design has been optimized to first order and is now under study for further modification and optimization. A 2-m three-mirror anastigmat wide-field telescope feeds a focal plane consisting of a 0.7 square-degree imager tiled with equal areas of optical CCDs and near infrared sensors, and a high-efficiency low-resolution integral field spectrograph. The instrumentation suite provides simultaneous discovery and light-curve measurements of supernovae and then can target individual objects for detailed spectral characterization. The SNAP mission will discover thousands of Type Ia supernovae out to z = 3 and will obtain high-signal-to-noise calibrated light-curves and spectra for a subset of > 2000 supernovae at redshifts between z = 0.1 and 1.7 in a northern field and in a southern field. A wide-field survey covering one thousand square degrees in both northern and southern fields resolves {approx} 100 galaxies per square arcminute, or a total of more than 300 million galaxies. With the PSF stability afforded by a space observatory, SNAP will provide precise and accurate measurements of gravitational lensing. The high-quality data available in space, combined with the large sample of supernovae, will enable stringent control of systematic uncertainties. The resulting data set will be used to determine the energy density of dark energy and parameters that describe its dynamical behavior. The data also provide a direct test of theoretical models for the dark energy, including discrimination of vacuum energy due to the ...
Date: August 15, 2005
Creator: Aldering, G.; Althouse, W.; Amanullah, R.; Annis, J.; Astier, P.; Baltay, C. et al.
Partner: UNT Libraries Government Documents Department

Boosted Objects: A Probe of Beyond the Standard Model Physics

Description: We present the report of the hadronic working group of the BOOST2010 workshop held at the University of Oxford in June 2010. The first part contains a review of the potential of hadronic decays of highly boosted particles as an aid for discovery at the LHC and a discussion of the status of tools developed to meet the challenge of reconstructing and isolating these topologies. In the second part, we present new results comparing the performance of jet grooming techniques and top tagging algorithms on a common set of benchmark channels. We also study the sensitivity of jet substructure observables to the uncertainties in Monte Carlo predictions.
Date: June 12, 2012
Creator: Abdesselam, A.; U., /Oxford; Kuutmann, E.Bergeaas; /DESY; Bitenc, U.; U., /Freiburg et al.
Partner: UNT Libraries Government Documents Department

Flavor Physics in the Quark Sector

Description: In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor. In this time frame, measurements and the theoretical interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved, apart from their masses and quantum numbers, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. In the past, observations of CP violation were confined to neutral K mesons, but since the early 1990s, a large number of CP-violating processes have been studied in detail in neutral B mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of K,D, and B mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments, thus a review of the status of quark flavor physics is timely. This report is the result of the work of the physicists attending the 5th CKM workshop, hosted by the University of Rome 'La Sapienza', September 9-13, 2008. It summarizes the results of the current generation of experiments that is about to be completed and it confronts these results with the theoretical understanding of the field which has greatly improved in the past decade.
Date: August 26, 2010
Creator: Antonelli, Mario; /Frascati; Asner, David Mark; U., /Carleton; Bauer, Daniel Adams; /Imperial Coll., London et al.
Partner: UNT Libraries Government Documents Department