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At least 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Measurement of $d^2 \sigma/d|\vec{q}|d E_{avail}$ and 2p2h contribution using charged current $\nu_\mu$ interactions in the NOvA Near Detector

This Thesis presents the analysis methods and measurement of the $d^2 \sigma/d|\vec{q}|d E_{avail}$-CC inclusive cross section that describes neutrino scattering in a predominantly hydrocarbon medium. Studies that are prerequisite for the analysis including, variable determinations, event selections, efficiency, purity determinations, and systematic uncertainty estimations, are summarized. Tests of the analysis are also detailed, and shown to reproduce the input distributions. The double-differential cross-section measurement provides the foundation for determination of the inclusive rate for the excess induced by 2p2h processes together with nuclear medium effects that are not described by the Fermi gas model. The methodology for the extraction of this rate, defined as the excess observed relative to the rate estimated for known single-nucleon interactions, is described in detail. The following new measurements are reported in this Thesis: (1) The $\nu_\mu-$CC inclusive double-differential cross section as a function of three-momentum transfer and available hadronic energy, for an average $E_\nu$ of 1.8 GeV, is obtained. The double-differential cross section value that obtains when the bin widths are taken to be the dimensions of the entire analysis domain, e.g. $0.2 \le |\vec{q}| \le 2.0 GeV/c$ and $0.0 \le E_{avail} \le 2.0$ GeV, is inclusive cross section is $(6.05 \pm 0.75)\times10^{-39}$ cm$^2$/GeV/GeV/$c$/nucleon. An event excess attributed to 2p2h-MEC processes is observed; most of the rate occurs in a contiguous phase space region $0.3 \le |\vec{q}| \le 1.0$ GeV$/c$ $0.0 \le E_{avail} \le 0.35$ GeV. This rate represents $12.0\pm 6.5\%$ of the observed CC inclusive cross section; its cross section ratio relative to CCQE scattering is estimated to be $44.3 \pm 23.9\%$.

Olson, Travis Grant↗
DOE OSTI2018

Semi-inclusive Neutral Current Neutral Pion Production Selection at the NOvA (NuMI Off-axis Electron Neutrino Appearance) Near Detector Using Prong Level Convolutional Neural Networks

The NONA neutrino experiment based in Fermilab is designed to measure ν µ →ν e neutrino oscillations. This experiment will give us insight into the properties of massive neutrinos. Neutral current (NC) ν µ,e neutral pion production events can mimic the ν µ →ν e oscillation signal and therefore are an important background for NONA to understand. Neutral pions decay into two photons which can fake a single electron shower (νe appearance signal) in two ways: either the 2 photons can merge together or one of them may escape detection. In order to constrain this background, NONA utilizes the Near Detector to measure neutral current π 0 neutrino interactions. In this analysis, neutrino-Nucleus (ν µ →N) NC π 0 interactions with total pion energy greater then 0.3 GeV are studied by selecting two prong events with two final state photons as determined by prong based Convolutional Visual Networks (CVN). The analysis is performed on 3.54x10 21 Protons On Target (POT) of NONA Near Detector simulated data and compared to 8.09x10 20 POT of data. Optimization of the selection based on fractional cross-section uncertainty and an initial energy resolution study of the final sample are presented. The final 2 prong selection using prong based CVN gave a purity of 74%, selection efficiency of ~ 1.8%, and an expected (NC) ν µ,e neutral pion cross section of ~ 15.2%.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Studies on the Module Structure for the NOvA Liquid Scintillator Neutrino Detector

This thesis contains studies pertinent to the construction of modules for the NOνAexperiment detectors. The tensile strength of acrylic and epoxy adhesives used in construction of the detector was studied over time and with various surface preparations. Sanding and corona discharge surface treatments increased the bond strength of the acrylic by 10-20%; aging in oil did not affect the acrylic bond strength while aging in air at 50°C for 9 months (equivalent to approximately 5 years at room temperature) increased the acrylic bond strength by 25%. For the epoxy, corona discharge treated samples’ strength increased slightly after aging while the strength of sanded samples in air remained consistent and sanded samples in oil decreased by 17% when aged at 50°C for 1.5 years (equivalent to approximately 10 years at room temperature).All materials used in the detector were studied to determine if degrading interaction would occur with the pseudocumene liquid scintillator. Substances such as acrylic adhesive and PTFE paste were found to interact with the scintillator while materials such as a variety of PVCs, epoxy adhesives, and PTFE tape were found to be non-reactive with the scintillator. Following the appearance of cracks on manifold covers in installed modules, studies were carried out to help to determine the cause and mitigation of these cracks. Manifold covers that had been pressure tested at various pressures during the check of the seals during the manufacturing process were examined for the formation of cracks. “Containment units” were used to constrain the swelling of the manifold covers during pressure testing. Internal cracks were visible on the majority of manifold covers tested at 1.4 bar with the original containment units. It was found that reducing the pressure testing of the modules from 1.4 bar to 0.7 bar and increasing the rigidity of the pressure test containment units eliminated the formation of visible cracks in the manifold covers. Stress concentration in small fillet radius injection molded PVC was studied. GeonM3500 PVC has a yield strength 12% greater than Geon M3800 PVC originally used for the manifold covers but increased the stress concentrated failure time by 6600% and was thus chosen to mold new manifold covers after a redesign to eliminate stress concentrating features.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Standard and Non-Standard Neutrino Oscillations at the NOvA Experiment

Initially believed to be massless, the discovery of neutrino oscillations proved that neutrinos have masses, a feature not anticipated by the Standard Model of Elementary Particles. Investigations of the existence of the so-called physics Beyond the Standard Model is a subject of active effort in the field of particle physics. Interactions of neutrinos with matter are well described by the Standard Model, however in the presence of new physics our knowledge and ability to measure the standard neutrino oscillation parameters may be affected. Non-Standard Interactions (NSI) may arise as a subleading effect to the neutrino oscillation framework by introducing additional parameters resulting from a generalized matter potential.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Study of neutrino oscillations and flux systematics in the NOvA experiment at Fermilab

The Standard Model of particle physics explains many experimental results using three generations of quarks, leptons, and their interactions, but fails to account for phenomena such as neutrino masses, matter-antimatter asymmetry, gravity, and the hierarchy problem. The study of neutrinos, especially neutrino oscillations, is crucial for advancing Beyond the Standard Model physics and the future of particle physics.newline

Sharma, Prachi [Panjab U.] (ORCID:0000000276586664↗
NASA NTRS1996

Research activities in nuclear astrophysics and related areas

NASA/GRO grant NAG 5-2081, at the University of Chicago, has provided support for a broad program of theoretical research in nuclear astrophysics and related areas, with regard to gamma-ray and hard X-ray emission from classical nova explosions. This research emphasized the possible detection of 22Na gamma-ray line emission from nearby novae involving ONeMg white dwarfs, the detailed examination of 26Al production in novae, and the possible detection of the predicted early gamma ray emission from novae that arises from the decay of the short lived, positron emitting isotopes of CNO elements. Studies of nova related problems have consumed an increasing fraction of the Principal Investigator's research efforts over the past decade. Current research addresses problems associated with the standard model for the outbursts of the classical novae: the occurrence of thermonuclear runaways (TNR) in the accreted hydrogen rich envelopes on white dwarfs in close binary systems (see, e.g., the reviews by Truran 1982; and Shara 1989). Research in progress and planned for the next three years has three main objectives: (1) to gain an improved understanding of the early evolution of the light curves of, particularly, the fastest novae; (2) to gain an improved understanding of the relative importance of the various possible mechanisms of envelope hydrogen depletion (e.g. winds, common envelope driven mass loss, and nuclear burning) to the long term evolution of novae in outburst; and (3) to seek to provide a somewhat more definitive statement of the role of classical novae in nucleosynthesis. Our proposed 2-D studies of convection during the early phases of the TNR and our systematic attempt to incorporate an improved treatment of radiation hydrodynamics into the hydrodynamic code utilized in our calculations, are particularly relevant to the first of these objectives. Further 2-D studies of the effects of common envelope evolution are intended to provide more realistic constraints on the mass depletion mechanisms. Finally, detailed calculations of the thermonuclear history of the matter ejected in novae will be carried out for representative nova configurations involving both carbon-oxygen (CO) and oxygen-neon-magnesium (ONeMg) white dwarfs.

Source record↗
NASA NTRS1990

The inter-outburst behavior of cataclysmic variables

Existing International Ultraviolet Explorer (IUE) and American Association of Variable Star Observers (AAVSO) archive data was used to accomplish a large scale study of what happens to the ultraviolet flux of accretion disk systems during the quiescent intervals between outbursts and how it relates to the preceding outburst characteristics of amplitude and width. The data sample involved multiple IUE observations for 16 dwarf novae and 8 novae along with existing optical coverage. Results indicate that most systems show correlated ultraviolet (UV) flux behavior with interoutburst phase, with 60 percent of the dwarf novae and 50 percent of the novae having decreasing flux trends while 33 percent of the dwarf novae and 38 percent of the novae show rising UV flux during the quiescent interval. All of the dwarf novae with decreasing UV fluxes at 1475A have orbital periods longer than 4.4 hours, while all (except BV Cen) with flat or rising fluxes at 1475A have orbital periods less than two hours. There are not widespread correlations of the UV fluxes with the amplitude of the preceding outburst and no correlations with the width of the outburst. From a small sample (7) that have relatively large quiescent V magnitude changes between the IUE observations, most show a strong correlation between the UV and optical continuum. Interpretation of the results is complicated by not being able to determine how much the white dwarf contributes to the ultraviolet flux. However, it is now evident that noticeable changes are occurring in the hot zones in accreting systems long after the outburst, and not only for systems that are dominated by the white dwarf. Whether these differences are due to different outburst mechanisms or to changes on white dwarfs which provide varying contributions to the UV flux remains to be determined.

Szkody, Paula↗
NASA NTRS1991

The interoutburst behavior of cataclysmic variables

Existing IUE and AAVSO archive data were used to accomplish a large scale study of what happens to the UV flux of accretion disk systems during the quiescent intervals between outbursts, and how it relates to the preceding outburst characteristics of amplitude and width. The data sample involved multiple IUE observations for 16 dwarf novae and 8 novae along with existing optical coverage. Results indicate that most systems show correlated UV flux behavior with interoutburst phase, with 60 percent of the dwarf novae and 50 percent of the novae having decreasing flux trends while 33 percent of the dwarf novae and 38 percent of the novae show rising UV flux during the quiescent interval. All of the dwarf novae with decreasing UV fluxes at 1475 A have orbital periods longer than 4.4 hours, while all (except BV Cen) with flat or rising fluxes at 1475 A have orbital periods less than two hours. From a small sample (7) that have relatively large quiescent V magnitude changes between the IUE observations, most show a strong correlation between the UV and optical continuum. Interpretation of the results is complicated by not being able to determine how much the white dwarf contributes to the ultraviolet flux. However, it is now evident that noticeable changes are occurring in the hot zones in accreting systems long after the outburst, and not only for systems that are dominated by the white dwarf.

Szkody, Paula↗