Long-Term Testing and Properties of Acrylic for the Daya Bay Antineutrino Detectors

The Daya Bay reactor antineutrino experiment has recently measured the neutrino mixing parameter sin22{\theta}13 by observing electron antineutrino disappearance over kilometer-scale baselines using six antineutrino detectors at near and far distances from reactor cores at the Daya Bay nuclear power complex. Liquid scintillator contained in transparent target vessels is used to detect electron antineutrinos via the inverse beta-decay reaction. The Daya Bay experiment will operate for about five years yielding a precision measurement of sin22{\theta}13. We report on long-term studies of poly(methyl methacrylate) known as acrylic, which is the primary material used in the fabrication of the target vessels for the experiment's antineutrino detectors. In these studies, acrylic samples are subjected to gaseous and liquid environmental conditions similar to those experienced during construction, transport, and operation of the Daya Bay acrylic target vessels and detectors. Mechanical and optical stability of the acrylic as well as its interaction with detector liquids is reported.Comment: 17 pages, 13 figures Submitted to JINS

Media-Rich Input Application Liability

Until recently, media-rich online interactions were mostly unidirectional: multimedia content was delivered by the service provider to the user. Input from the user came almost exclusively in the form of text. Even when searching the Internet for images or audio, a user typically entered text into a search engine. In addition, search engines indexed multimedia content by analyzing not the content itself but the text surrounding it. This is rapidly changing. With the rise of multimedia-capable smartphones and wireless broadband, applications that allow users to search using non-textual inputs are quickly becoming popular. These applications go much further than simply allowing content to be uploaded and shared, which is already common to Web 2.0 applications; they actually respond to the user based on the input media.[...] These applications represent a new and growing category that I term media-rich input applications (MRIAs).[...] There are three unique attributes of MRIAs that differentiate them from legacy web behavior and therefore require new analysis. First, unlike legacy search applications in which the service provider makes a copy and presents it to the user, MRIA behavior requires the user to make a copy and present it to the service provider. Thus, the image of the book cover in the previous example is digitized by the user and sent to Google; it is not copied by Google and sent to the user in response to a search. Second, the copied content is not necessarily from the Internet; in our example it is from a physical book. Third, some of these technologies create derivative works in a way that simple web searching and indexing does not. This Essay examines how these unique features of MRIAs interact with current copyright doctrine and how the lack of protection for users may discourage innovation by developers of this new and exciting technology. This Essay also proposes a new user safe harbor that balances the interests of users in using MRIAs with the interests of copyright owners in protecting their exclusive rights

Irreducibility and reducibility for the energy representation of the group of mappings of a Riemannian manifold into a compact semisimple Lie group

AbstractThe irreducibility of the energy representation of the group of smooth mappings from a Riemannian manifold of dimension d ⩾ 3 into a compact semisimple Lie group is proven. The nonequivalence of the representations associated with different Riemann structures is also proven for d ⩾ 3. The case d = 2 is examined and irreducibility and nonequivalence results are also given. The reducibility in the case d = 1 is pointed out (in this case the commutant contains a representation equivalent with the energy representation)

Factoriality of representations of the group of paths on SU(n)

AbstractFactoriality in the cyclic component of the vacuum for the energy representation of SU(n)-valued paths groups is proved. The main tool is a lemma concerning generic pairs of Cartan subalgebras in the Lie algebra su(n) of SU(n) groups

Jet Trimming

Initial state radiation, multiple interactions, and event pileup can contaminate jets and degrade event reconstruction. Here we introduce a procedure, jet trimming, designed to mitigate these sources of contamination in jets initiated by light partons. This procedure is complimentary to existing methods developed for boosted heavy particles. We find that jet trimming can achieve significant improvements in event reconstruction, especially at high energy/luminosity hadron colliders like the LHC.Comment: 20 pages, 11 figures, 3 tables - Minor changes to text/figure

Quantum electrodynamics of relativistic bound states with cutoffs

We consider an Hamiltonian with ultraviolet and infrared cutoffs, describing the interaction of relativistic electrons and positrons in the Coulomb potential with photons in Coulomb gauge. The interaction includes both interaction of the current density with transversal photons and the Coulomb interaction of charge density with itself. We prove that the Hamiltonian is self-adjoint and has a ground state for sufficiently small coupling constants.Comment: To appear in "Journal of Hyperbolic Differential Equation

Feasibility study for a numerical aerodynamic simulation facility. Volume 1

A Numerical Aerodynamic Simulation Facility (NASF) was designed for the simulation of fluid flow around three-dimensional bodies, both in wind tunnel environments and in free space. The application of numerical simulation to this field of endeavor promised to yield economies in aerodynamic and aircraft body designs. A model for a NASF/FMP (Flow Model Processor) ensemble using a possible approach to meeting NASF goals is presented. The computer hardware and software are presented, along with the entire design and performance analysis and evaluation