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- Title
- DESIGN OF A COVARIANCE MATRIX FITTER TO MEASURE THE ELECTRON ANTINEUTRINO OSCILLATION PARAMETERS USING NEUTRON HYDROGEN CAPTURE AT THE DAYA BAY EXPERIMENT
- Creator
- De Arcos Rodr´iguez, Jos´e Fernando
- Date
- 2015, 2015-12
- Description
-
The Daya Bay experiment provided the first precision measurement of the third mixing angle of the Pontecorvo-Maki-Nakagawa-Sakata matrix (✓13)...
Show moreThe Daya Bay experiment provided the first precision measurement of the third mixing angle of the Pontecorvo-Maki-Nakagawa-Sakata matrix (✓13) using six detectors to determine the relative rates of correlated signals generated from gadolinium neutron capture and positron-electron annihilation gammas in the inverse beta decay process. An additional correlated hydrogen neutron capture signal is produced in the Daya Bay detectors. Its analysis has the potential of producing an independent measurement of the electron antineutrino oscillation parameters. In this thesis a fitter has been designed to measure ✓13 and the squared mass di↵erence (#m2 ee) using the shape information of the hydrogen neutron capture signal generated in the Daya Bay experiment detectors. The main challenges of the hydrogen capture signal are the high accidental background rates in the lower energy region, and hydrogen’s neutron capture cross-section being much lower than gadolinium’s. In order to have a significant signal, we had to use more aggressive selection cuts than those applied in the gadolinium neutron capture analysis, and the fiducial volume was expanded by including the gadolinium-free gamma catcher region. Both background and detector systematic uncertainties studies have been repeated for the new hydrogen signal conditions. The results of these studies have been used to produce the corresponding covariance matrices that account for the uncertainties in a covariance matrix fitter. The fitter is customizable, i.e., energy binning, antineutrino detector configuration, data periods to be fitted, reactor periods, detector response matrices and predictions can be configured using a graphical user interface, providing versatility for further research. The fitter performance has been tested in the two dimensional parameter space S ⇥ D, where S = !sin2(2✓13) 2 [0, 0.002, 0.004, ...0.2]} and D = {#m2 ee 2 [0.0015, 0.00152, 0.00154...0.0035]}, using nominal and statistically fluctuated antineutrino spectrum predictions.
Ph.D. in Physics, December 2015
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- Title
- SEARCH FOR STERILE NEUTRINO OSCILLATIONS WITH THE PROSPECT EXPERIMENT
- Creator
- Surukuchi, Pranava Teja
- Date
- 2019
- Description
-
Neutrinos have been one of the most interesting particles to study for the best part of the last century. Ever since the first discovery of...
Show moreNeutrinos have been one of the most interesting particles to study for the best part of the last century. Ever since the first discovery of neutrinos, various experiments using both natural and artificial neutrino sources have helped in determining the nature of neutrinos. In particular, experiments in the last two decades helped determine the neutrino oscillation parameters. Although three neutrino picture is well established, discrepancies have been observed in some recent reactor, accelerator, and source neutrino experiments hinting at the existence of a fourth weakly non-interacting neutrino called a sterile neutrino. Additional experimental investigation is needed to test the sterile neutrino hypothesis and identify the source of discrepancies. PROSPECT is a short-baseline reactor antineutrino experiment designed to search for sterile neutrinos and make a precise measurement of 235U reactor antineutrino spectrum from the High Flux Isotope Reactor at Oak Ridge National Laboratory located in Tennessee. The PROSPECT detector is segmented with 6Li-loaded liquid scintillator as the target. The design and development of the PROSPECT detector started in 2014 and the assembly and installation have finished by early 2018. PROSPECT detector has been collecting data since March 2018. The design, development, and installation of the detector is discussed with a particular emphasis on the components designed and developed at Illinois Institute of Technology. The detector calibration, event reconstruction, and data quality are also discussed. Finally, the sterile neutrino search using 33 days of reactor on data and 29 days of reactor off data is presented.
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- Title
- Energy Scale Study for PROSPECT's Measurement of the Antineutrino Spectrum of 235U
- Creator
- Zhang, Xianyi
- Date
- 2019
- Description
-
Neutrinos from nuclear fission reactors have been widely studied in particle and nuclear physics. In the last ten years, the antineutrino flux...
Show moreNeutrinos from nuclear fission reactors have been widely studied in particle and nuclear physics. In the last ten years, the antineutrino flux and spectrum were measured independently by short baseline reactor experiments. Both flux and spectrum measurements showed discrepancies compared to theoretical models based on historical measurements and nuclear databases. These discrepancies hint at sterile neutrino oscillation at the eV mass scale, as well as an incomplete theoretical model. PROSPECT, the Precision Reactor Oscillation and Spectrum experiment, was built to probe for sterile neutrino oscillations and precisely measure the reactor antineutrino spectrum from a highly 235U enriched reactor. The PROSPECT antineutrino detector is an optically segmented liquid scintillator detector deployed at seven meters to nine meters from the High Flux Isotope Reactor at Oak Ridge National Laboratory. This dissertation details the analysis to calibrate the energy scale of the PROSPECT antineutrino detector, an essential step for both the oscillation and spectrum measurements. To characterize the nonlinear detector energy response, a unique calibration and analysis strategy was developed to overcome challenges brought on by particle multi-segment scattering within the PROSPECT detector. With the calibrated scale for energy reconstruction, PROSPECT measured of the antineutrino spectrum from a 235U-burning reactor.
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