Spelling suggestions: "subject:"high energy"" "subject:"igh energy""
11 |
Particle production at high energiesUng-Kitchanukit, Ahpisit January 1977 (has links)
An explicit Mueller-Regge model is constructed for the investigations of one-particle-inclusive 2 processes in the fixed-M and triple-Regge region. The model is then applied in the studies of [delta] production and vector and tensor meson productions. The inclusive cross sections and density matrices of the decaying produced resonances are considered and compared with the available data. The qualitative behaviour of the cross section data can be approximately accounted for by the model, but the model is not satisfactory in details. By analogy with two-body processes absorption is introduced and the resultant model with cuts is used in the reinvestigations of the data. There is some improvement in the agreement between the model and the data with the introduction of absorption.
|
12 |
Evidence for e+e - to gammaetac(1S) at center-of-mass energies between 4.01 and 4.60 GeV at BESIIILara, Manuel 01 October 2016 (has links)
<p> This dissertation shows the first evidence of the process <i>e</i><sup> +</sup><i>e</i><sup>−</sup> → γη<i><sub> c</sub></i>(1<i>S</i>) using data collected by the BESIII experiment operating at BEPCII. This process can be used as a probe to study the nature of recently discovered charmonium-like Y states between 4.0 and 4.6 GeV, including the <i>Y</i>(4260) and <i>Y</i>(4360). Data collected at six center-of-mass energies are analyzed, namely: 4.01, 4.23, 4.26, 4.36, 4.42, and 4.60 GeV, corresponding to a total integrated luminosity of 4.6 fb<sup>−1</sup>. We measure the Born cross section, σ<i><sub> E</sub></i>(<i>e</i><sup>+</sup><i>e</i><sup> −</sup> → γη<i><sub>c</sub></i>(1<i> S</i>)), at each energy using a combination of twelve η<i><sub> c</sub></i>(1<i>S</i>) decay channels. Because the significance of the signal is marginal at each energy (≤ 3.0σ), we also combine all six energies under various assumptions for the energy-dependence of the cross section. If a <i>Y</i>(4260) is assumed, we measure σ4<sub> .26</sub>(<i>e</i><sup>+</sup><i>e</i><sup>− </sup> → γη<i><sub>c</sub></i>(1<i>S</i>)) = 2.11 ± 0.49 (stat.) ± 0.33 (syst.) pb with a significance of 4.2σ. With our current statistics we are unable to distinguish the <i> Y</i>(4260) process from others.</p>
|
13 |
Measurement of Single pi0 Production in Neutral Current Neutrino Interactions on Water at the Near Detector of the T2K ExperimentVallari, Zoya 17 April 2019 (has links)
<p> T2K is a long baseline neutrino oscillation experiment located in Japan. It was built mainly to detect muon neutrino to electron neutrino oscillation and to measure the mixing angle &thetas;<sub>13</sub> of the PMNS matrix, along with the precision measurement of &thetas;<sub>23</sub> and mass differences. A ν<sub>μ</sub> beam is produced at the Japan Proton Accelerator Research Complex (J-PARC) in Tokai and travels to the far detector in Kamioka, Japan. There is an ensemble of detectors at 280 m downstream of the target that form the near detector. Super-Kamiokande, a water Cherenkov detector, located 295 km away from the target serves as the far detector. </p><p> The two main backgrounds for electron neutrino appearance at the Super-Kamiokande are the inherent electron neutrino component of the beam and the \pizero{} particle produced via neutral current channel (NC1π<sup>0</sup>) that mimics the electron neutrino interaction signature. To effectively constrain the NC1π<sup>0</sup> interaction rate on water, the Pi0 Detector (P0D) was built as one of the near detectors. This detector can be filled and drained with water periodically to enable extraction of neutrino interactions on water. </p><p> This analysis measures the NC1π<sup>0</sup> interaction rate on water in the P0D. It uses neutrino beam data of 3.53 × 10<sup>20</sup> protons-on-target (POT) for the water-in configuration of the P0D and 6.70 × 10<sup>20</sup> POT for the water-out configuration. A set of selections are implemented to obtain a sample enriched in signal events. </p><p> The π<sup>0</sup> invariant mass distribution is compared between data and Monte Carlo. Parameter estimation using Markov Chain Monte Carlo sampling method is performed to measure the signal events in data. </p><p> The data fit results in 130 ± 20 events on water including both statistical and systematic uncertainties for an expected value of 167 events predicted by the NEUT Monte Carlo. The ratio between nominal Monte Carlo and the best fit value is 0.78 ± 0.12.</p><p>
|
14 |
Searches for Supersymmetry, RECAST, and Contributions to Computational High Energy PhysicsHeinrich, Lukas 02 April 2019 (has links)
<p> The search for phenomena Beyond the Standard Model (BSM) is the primary motivation for the experiments at the Large Hadron Collider (LHC). This dissertation assesses the experimental status of supersymmetric theories based on analyses of data collected by the ATLAS experiment during the first and second run of the LHC. Both R-parity preserving theories defined within the framework of the Minimally Supersymmetric Standard Model (MSSM) as well as R-parity violating models are studied. Further, a framework for systematic reinterpretation, RECAST, is presented which enables a streamlined, community-wide, approach to the search for BSM physics through the preservation of data analyses as parametrized computational workflows. A language and execution engine for such workflows of heterogeneous workloads on distributed computing systems is presented. Additionally, a new implementation of the HistFactory class of binned likelihoods based on auto-differentiable computational graphs is developed for accelerated and distributed inference computation. Finally, to enable efficient reinterpretation, a method of estimating excursion sets of one or more resource-intensive, multivariate, black-box functions, such as p-value functions, through an information-based Bayesian Optimization procedure is introduced.</p><p>
|
15 |
High velocity formability and factors affecting itDehra, Mala Seth, January 2006 (has links)
Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 302-314).
|
16 |
Superconducting X-ray Spectrometers for High-Resolution Synchrotron XASCarpenter, Matthew Hollis 01 October 2015 (has links)
<p> X-ray absorption spectroscopy (XAS) is a powerful technique to determine the structure and function of molecules. It provides element-specific information on geometry, chemical bonding, oxidation state, and spin state, and its applications range from biology to material science. For dilute samples, XAS is measured by partial fluorescence yield (PFY), where the intensity of a weak fluorescence line is recorded as a measure of absorption as the energy of the incident x-ray beam is scanned across an absorption edge of the element of interest. PFY increases the sensitivity for XAS if an x-ray detector is used that can efficiently separate the small fluorescence signal of interest from the x-ray background due to other elements in the sample. </p><p> This dissertation describes the development of a high-resolution x-ray detector based on arrays of superconducting tunnel junctions (STJs). It is cooled to its operating temperature below 0.3 K with a liquid-cryogen-free adiabatic demagnetization refrigerator cryostat, and offers more than an order of magnitude improvement in energy resolution over conventional Ge- or Si-based solid state detectors. For operation in XAS experiments at a synchrotron, the STJ detector array is held at the end of a cold finger that can be inserted into an ultra-high vacuum endstation. This dissertation describes the design and performance of the STJ x-ray spectrometer, and demonstrates its use in PFY-XAS experiments in metallo-organic compounds at the Advanced Light Source synchrotron.</p>
|
17 |
Proton acceleration experiment by high intensity laser pulse interaction with solid density target at the Texas Petawatt Laser FacilityKuk, Donghoon 20 February 2012 (has links)
In recent, high intensity laser pulse interaction with solid density matter has been studied in several laboratory and facilities. Multi-MeV proton and ion beams from plasma produced by this interaction is one important application research area of HEDP. In this thesis, the basic theory of hot electron generation associated with proton acceleration will be introduced. A basic proton acceleration mechanism called TNSA will be introduced with supplemental free plasma expansion model. To investigate proton acceleration at the Texas Petawatt Facility, the experimental set up and target alignmen will be introduced in the chapter 5. While the analysis of data acquired from this experiment is still unfinished, a brief result with RCF image will be introduced in chapter 6. / text
|
18 |
A Search for Z' Gauge Bosons Decaying to Tau-Antitau Pairs in Proton-Proton Collisions with the ATLAS DetectorLeister, Andrew Gerard 08 August 2015 (has links)
<p>Many Beyond-the-Standard-Model theories predict the existence of one or more additional neutral gauge bosons, or <i>Z'</i> bosons, with masses at the TeV scale or higher. A search for resonances of <i>Z'</i> bosons decaying to τ<sup>+</sup> τ<sup>-</sup> pairs in [special characters omitted]<i>s</i> = 8 TeV <i>pp</i> collisions from the LHC is presented. The data was collected by the ATLAS detector and corresponds to an integrated luminosity of 19.5-20.3 fb<sup>-1</sup>. The search is performed in ditau decay channels in which at least one tau decays hadronically. In each channel, the numbers of ditau events in high-mass regions of data are counted and compared to the expected numbers from Standard Model backgrounds and <i>Z'</i> signals. No statistically significant excess above the Standard Model expectation is observed in any channel. Bayesian 95% credibility upper limits are placed on the <i>Z'</i> production cross section times <i>Z'</i> → ττ branching ratio as functions of the <i>Z'</i> resonance mass for each channel and for a combination of the channels. Sequential Standard Model <i>Z'</i> bosons with masses below 2.02 TeV are excluded at 95% credibility. The impacts on the cross section limits from varying the <i>Z<sub>ssM</sub></i> decay width and couplings to fermions are evaluated. Limits are also placed on the cross section times branching ratio of Non-Universal <i>G</i>(221) <i> Z'</i> bosons with enhanced couplings to third-generation fermions. These are evaluated as functions of the <i>Z'<sub>NU</sub></i> mass and another free parameter. <i>Z'<sub>Nu</sub></i> bosons with masses below 1.3-2.1 TeV are excluded at 95% credibility.</p>
|
19 |
xy Position Reconstruction in DarkSide-50Brodsky, Jason Philip 24 October 2015 (has links)
<p> The DarkSide-50 experiment seeks to directly detect dark matter in a liquid argon time projection chamber. In this dissertation, I present an algorithm of my design that determines the position of particle interactions with the liquid argon. This position reconstruction algorithm will be used by DarkSide-50 to reject backgrounds, particularly backgrounds from radioactive elements on the detector surface.</p><p> The position reconstruction algorithm functions by constructing light response functions (LRFs) that map locations in the detector to the expected distribution of signal in DarkSide-50's 38 photomultiplier tubes. Accurate LRFs cannot be produced by simulations of DarkSide-50's optics because such simulations are known to be flawed. Instead, this algorithm constructs LRFs using an iterative process driven by data. Initial, flawed LRFs are produced using simulated events but then used to produce new LRFs from data events. Multiple generations of LRFs are created from data with each generation driven to better satisfy a known feature of the detector: the dominant argon-39 background is uniformly distributed.</p><p> I also discuss a method of discriminating against surface background as an alternative to the common approach of fiducialization. This method considers the difference in goodness-of-fit between the best-fit reconstructed position and the best-fit position at the detector's surface.</p><p> I conclude by presenting results on the performance and validity of this algorithm, including some discussion of reconstruction errors. </p>
|
20 |
Power Counting Rules for Next-to-Leading Order Hard Thermal Loop TheoryMirza, Alex 20 April 2012 (has links)
The goal of this thesis is to determine power counting rules at next-to-leading order (NLO) in the hard
thermal loop (HTL) resummation. The original paper by Braaten and Pisarski discusses NLO HTL resummation
and argues that there are potentially three types of contributions. We start by studying these terms
in the specific case of the boson and fermion self energies in QED and QCD, as these quantities have been
calculated in previous literature. For the real and imaginary parts of the fermion and gluon self energies,
one needs to calculate only one type of term, as the other two are found to be subleading. However, for the
real and imaginary parts of the photon self energy, all types of terms need to be calculated.
|
Page generated in 0.0594 seconds