249 research outputs found
The LHeC Detector
The Large Hadron Electron Collider (LHeC) is a proposed upgrade to the LHC,
to provide high energy, high luminosity electron-proton collisions to run
concurrently with Phase 2 of the LHC. The baseline design of a detector for the
LHeC is described, driven by the requirements from the projected physics
programme and including some preliminary results from first simulations.Comment: 6 pages, proceedings of parallel talk at Deep Inelastic Scattering
2013, 22-26 April 2013, Marseilles, Franc
A new detector for deep inelastic physics
The Large Hadron Electron Collider (LHeC) is a proposed upgrade to the LHC,
to provide high energy, high luminosity electron-proton and electron-ion
collisions to run concurrently with Phase 2 of the LHC. The key elements of the
LHeC detector and the requirements from the physics programme are outlined,
followed by a brief description of the baseline LHeC detector design.Comment: 3 pages, proceedings of poster at HEP-EPS 2013, July 18 - 24 2013,
Stockholm, Swede
Pseudo-Euler equations from nonlinear optics: plasmon-assisted photodetection beyond hydrodynamics
A great deal of theoretical and experimental efforts have been devoted in the
last decades to the study of long-wavelength photodetection mechanisms in
field-effect transistors hosting two-dimensional (2D) electron systems. A
particularly interesting subclass of these mechanisms is intrinsic and based on
the conversion of the incoming electromagnetic radiation into plasmons, which
resonantly enhance the photoresponse, and subsequent rectification via
hydrodynamic nonlinearities. In this Article we show that such conversion and
subsequent rectification occur well beyond the frequency regime in which
hydrodynamic theory applies. We consider the nonlinear optical response of
generic 2D electron systems and derive pseudo-Euler equations of motion for
suitable collective variables. These are solved in one- and two-dimensional
geometries for the case of graphene and the results are compared with those of
hydrodynamic theory. Significant qualitative differences are found, which are
amenable to experimental studies. Our theory expands the knowledge of the
fundamental physics behind long-wavelength photodetection.Comment: 15 pages, 4 figure
Photocurrent-based detection of Terahertz radiation in graphene
Graphene is a promising candidate for the development of detectors of
Terahertz (THz) radiation. A well-known detection scheme due to Dyakonov and
Shur exploits the confinement of plasma waves in a field-effect transistor
(FET), whereby a dc photovoltage is generated in response to a THz field. This
scheme has already been experimentally studied in a graphene FET [L. Vicarelli
et al., Nature Mat. 11, 865 (2012)]. In the quest for devices with a better
signal-to-noise ratio, we theoretically investigate a plasma-wave photodetector
in which a dc photocurrent is generated in a graphene FET. The rectified
current features a peculiar change of sign when the frequency of the incoming
radiation matches an even multiple of the fundamental frequency of plasma waves
in the FET channel. The noise equivalent power per unit bandwidth of our device
is shown to be much smaller than that of a Dyakonov-Shur detector in a wide
spectral range.Comment: 5 pages, 4 figure
Accessing phonon polaritons in hyperbolic crystals by ARPES
Recently studied hyperbolic materials host unique phonon-polariton (PP)
modes. The ultra-short wavelengths of these modes, which can be much smaller
than those of conventional exciton-polaritons, are of high interest for extreme
sub-diffraction nanophotonics schemes. Polar hyperbolic materials such as
hexagonal boron nitride can be used to realize strong long-range coupling
between PP modes and extraneous charge degrees of freedom. The latter, in turn,
can be used to control and probe PP modes. Of special interest is coupling
between PP modes and plasmons in an adjacent graphene sheet, which opens the
door to accessing PP modes by angle-resolved photoemission spectroscopy
(ARPES). A rich structure in the graphene ARPES spectrum due to PP modes is
predicted, providing a new probe of PP modes and their coupling to graphene
plasmons
Plasmon losses due to electron-phonon scattering: the case of graphene encapsulated in hexagonal Boron Nitride
Graphene sheets encapsulated between hexagonal Boron Nitride (hBN) slabs
display superb electronic properties due to very limited scattering from
extrinsic disorder sources such as Coulomb impurities and corrugations. Such
samples are therefore expected to be ideal platforms for highly-tunable
low-loss plasmonics in a wide spectral range. In this Article we present a
theory of collective electron density oscillations in a graphene sheet
encapsulated between two hBN semi-infinite slabs (hBN/G/hBN). Graphene plasmons
hybridize with hBN optical phonons forming hybrid plasmon-phonon (HPP) modes.
We focus on scattering of these modes against graphene's acoustic phonons and
hBN optical phonons, two sources of scattering that are expected to play a key
role in hBN/G/hBN stacks. We find that at room temperature the scattering
against graphene's acoustic phonons is the dominant limiting factor for
hBN/G/hBN stacks, yielding theoretical inverse damping ratios of hybrid
plasmon-phonon modes of the order of -, with a weak dependence on
carrier density and a strong dependence on illumination frequency. We confirm
that the plasmon lifetime is not directly correlated with the mobility: in
fact, it can be anti-correlated.Comment: 14 pages, 4 figure
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