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Search Results: 1 - 10 of 582940 matches for " D. A. Dwyer "
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Oscillations at low energies
D. A. Dwyer,L. Ludhova
Physics , 2015,
Abstract: A concise summary of the "Oscillation at low energies" parallel session at the 2014 Neutrino Oscillation Workshop is provided. Plans to use man-made neutrinos and antineutrinos to determine the neutrino mass hierarchy, search for sterile neutrinos, and to observe coherent neutrino-nucleus scattering were discussed. Potential measurements of solar neutrinos, supernova neutrinos, and geoneutrinos are also summarized.
Spectral Structure of Electron Antineutrinos from Nuclear Reactors
D. A. Dwyer,T. J. Langford
Physics , 2014, DOI: 10.1103/PhysRevLett.114.012502
Abstract: Recent measurements of the positron energy spectrum obtained from inverse beta decay interactions of reactor electron antineutrinos show an excess in the 4 to 6 MeV region relative to current predictions. First-principle calculations of fission and beta decay processes within a typical pressurized water reactor core identify prominent fission daughter isotopes as a possible origin for this excess. These calculations also predict percent-level substructure in the antineutrino spectrum due to Coulomb effects in beta decay. Precise measurement of this substructure can constrain nuclear reactor physics. The substructure can be a systematic uncertainty for measurements utilizing the detailed spectral shape.
Mass Hierarchy Resolution in Reactor Anti-neutrino Experiments: Parameter Degeneracies and Detector Energy Response
X. Qian,D. A. Dwyer,R. D. McKeown,P. Vogel,W. Wang,C. Zhang
Physics , 2012, DOI: 10.1103/PhysRevD.87.033005
Abstract: Determination of the neutrino mass hierarchy using a reactor neutrino experiment at $\sim$60 km is analyzed. Such a measurement is challenging due to the finite detector resolution, the absolute energy scale calibration, as well as the degeneracies caused by current experimental uncertainty of $|\Delta m^2_{32}|$. The standard $\chi^2$ method is compared with a proposed Fourier transformation method. In addition, we show that for such a measurement to succeed, one must understand the non-linearity of the detector energy scale at the level of a few tenths of percent.
Search for Sterile Neutrinos with a Radioactive Source at Daya Bay
D. A. Dwyer,K. M. Heeger,B. R. Littlejohn,P. Vogel
Physics , 2011, DOI: 10.1103/PhysRevD.87.093002
Abstract: The far site detector complex of the Daya Bay reactor experiment is proposed as a location to search for sterile neutrinos with > eV mass. Antineutrinos from a 500 kCi 144Ce-144Pr beta-decay source (DeltaQ=2.996 MeV) would be detected by four identical 20-ton antineutrino targets. The site layout allows flexible source placement; several specific source locations are discussed. In one year, the 3+1 sterile neutrino hypothesis can be tested at essentially the full suggested range of the parameters Delta m^2_{new} and sin^22theta_{new} (90% C.L.). The backgrounds from six nuclear reactors at >1.6 km distance are shown to be manageable. Advantages of performing the experiment at the Daya Bay far site are described.
Measuring the Neutrino Mass Hierarchy with Atmospheric Neutrinos
D. F. Cowen,T. DeYoung,D. Grant,D. A. Dwyer,S. R. Klein,K. B. Luk,D. R. Williams,for the IceCube/PINGU Collaboration
Physics , 2014,
Abstract: The proposed PINGU experiment to measure the neutrino mass hierarchy is presented, in the context of long-range planning by the U.S. nuclear physics community.
Neutron Calibration Sources in the Daya Bay Experiment
J. Liu,R. Carr,D. A. Dwyer,W. Q. Gu,G. S. Li,R. D. McKeown,X. Qian,R. H. M. Tsang,F. F. Wu,C. Zhang
Physics , 2015, DOI: 10.1016/j.nima.2015.07.003
Abstract: We describe the design and construction of the low rate neutron calibration sources used in the Daya Bay Reactor Anti-neutrino Experiment. Such sources are free of correlated gamma-neutron emission, which is essential in minimizing induced background in the anti-neutrino detector. The design characteristics have been validated in the Daya Bay anti-neutrino detector.
Computing eigenvalues of regular Sturm-Liouville problems
H. I. Dwyer,A. Zettl
Electronic Journal of Differential Equations , 1994,
Abstract: of regular self-adjoint Sturm-Liouville problems with matrix coefficients and arbitrary coupled boundary conditions.
Eigenvalue computations for regular matrix Sturm-Liouville problems
H. I. Dwyer,A. Zettl
Electronic Journal of Differential Equations , 1995,
Abstract: of regular self-adjoint Sturm-Liouville problems with matrix coefficients and separated boundary conditions.
Collision-Induced Decay of Metastable Baby Skyrmions
Daniel A. Dwyer,Krishna Rajagopal
Physics , 2000, DOI: 10.1103/PhysRevD.62.105028
Abstract: Many extensions of the standard model predict heavy metastable particles which may be modeled as solitons (skyrmions of the Higgs field), relating their particle number to a winding number. Previous work has shown that the electroweak interactions admit processes in which these solitons decay, violating standard model baryon number. We motivate the hypothesis that baryon-number-violating decay is a generic outcome of collisions between these heavy particles. We do so by exploring a 2+1 dimensional theory which also possesses metastable skyrmions. We use relaxation techniques to determine the size, shape and energy of static solitons in their ground state. These solitons could decay by quantum mechanical tunneling. Classically, they are metastable: only a finite excitation energy is required to induce their decay. We attempt to induce soliton decay in a classical simulation by colliding pairs of solitons. We analyze the collision of solitons with varying inherent stabilities and varying incident velocities and orientations. Our results suggest that winding-number violating decay is a generic outcome of collisions. All that is required is sufficient (not necessarily very large) incident velocity; no fine-tuning of initial conditions is required.
The Relationship between Energy Literacy and Environmental Sustainability  [PDF]
Catherine Dwyer
Low Carbon Economy (LCE) , 2011, DOI: 10.4236/lce.2011.23016
Abstract: Sustainability, first identified as a characteristic of eco-systems, is the capacity to maintain a process indefinitely. Environmental sustainability receives significant public and government attention, triggered by concerns about climate change, decreasing energy supplies, and increasing food costs. Colleges and universities receive positive notice for their greening efforts, and the academy is expected to be a leader in efforts to improve sustainability. Therefore coursework and curricula must be developed to train students about sustainable resource consumption processes. This paper describes curricula materials related to energy literacy, defined as conceptual fluency with the economic and social components of energy use. These materials were developed and piloted over a three year period, and were tested with a pre- and post-course survey administered with questions based on the New Environmental Paradigm (NEP) and Environmentally Responsible Behavior (ERB). The findings of this study suggest that discussion of sustainability with disaster themes triggers anxiety that interferes with the development of ERB. In contrast, materials emphasizing the pragmatic necessity and benefits derived from sustainable practices relate to improvements in ERB. This suggests sustainability curricula should mitigate anxiety aroused by the topic, and instead emphasize pragmatic motivations for changing energy consumption patterns.
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