398 research outputs found
A Compact Gas Cerenkov Detector with Novel Optics
We discuss the design and performance of a threshold Cerenkov counter for
identification of charged hadrons. The radiator is pressurized gas, which is
contained in thin-walled cylindrical modules. A mirror system of novel design
transports Cerenkov photons to photomultiplier tubes. This system is compact,
contains relatively little material, and has a large fraction of active volume.
A prototype of a module designed for the proposed CLEO III detector has been
studied using cosmic rays. Results from these studies show good agreement with
a detailed Monte Carlo simulation of the module and indicate that it should
achieve separation of pions and kaons at the 2.5-3.0sigma level in the momentum
range 0.8-2.8 GeV/c. We predict performance for specific physics analyses using
a GEANT-based simulation package.Comment: Submitted to NIM. 23 pages, 11 postscript figures. Postscript file is
also available at http://w4.lns.cornell.edu/public/CLNS/199
Manual sobre criação de galinha caipira na agricultura familiar: noçÔes båsicas.
bitstream/item/61192/1/CPATU-Doc114.pd
Manual sobre criação de suĂnos na agricultura familiar: noçÔes bĂĄsicas.
bitstream/item/61199/1/CPATU-Doc115.pd
Multi-phonon Raman scattering in semiconductor nanocrystals: importance of non-adiabatic transitions
Multi-phonon Raman scattering in semiconductor nanocrystals is treated taking
into account both adiabatic and non-adiabatic phonon-assisted optical
transitions. Because phonons of various symmetries are involved in scattering
processes, there is a considerable enhancement of intensities of multi-phonon
peaks in nanocrystal Raman spectra. Cases of strong and weak band mixing are
considered in detail. In the first case, fundamental scattering takes place via
internal electron-hole states and is participated by s- and d-phonons, while in
the second case, when the intensity of the one-phonon Raman peak is strongly
influenced by the interaction of an electron and of a hole with interface
imperfections (e. g., with trapped charge), p-phonons are most active.
Calculations of Raman scattering spectra for CdSe and PbS nanocrystals give a
good quantitative agreement with recent experimental results.Comment: 16 pages, 2 figures, E-mail addresses: [email protected],
[email protected], [email protected], accepted for publication in
Physical Review
From thermal rectifiers to thermoelectric devices
We discuss thermal rectification and thermoelectric energy conversion from
the perspective of nonequilibrium statistical mechanics and dynamical systems
theory. After preliminary considerations on the dynamical foundations of the
phenomenological Fourier law in classical and quantum mechanics, we illustrate
ways to control the phononic heat flow and design thermal diodes. Finally, we
consider the coupled transport of heat and charge and discuss several general
mechanisms for optimizing the figure of merit of thermoelectric efficiency.Comment: 42 pages, 22 figures, review paper, to appear in the Springer Lecture
Notes in Physics volume "Thermal transport in low dimensions: from
statistical physics to nanoscale heat transfer" (S. Lepri ed.
Electrophysiological Evidence of Atypical Spatial Attention in Those with a High Level of Self-reported Autistic Traits
Selective attention is atypical in individuals with autism spectrum conditions. Evidence suggests this is also the case for those with high levels of autistic traits. Here we investigated the neural basis of spatial attention in those with high and low levels of self-reported autistic traits via analysis of ERP deflections associated with covert attention, target selection and distractor suppression (the N2pc, NT and PD). Larger N2pc and smaller PD amplitude was observed in those with high levels of autistic traits. These data provide neural evidence for differences in spatial attention, specifically, reduced distractor suppression in those with high levels of autistic traits, and may provide insight into the experience of perceptual overload often reported by individuals on the autism spectrum
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