10,307 research outputs found
Software digitizer for high granular gaseous detector
A sampling calorimeter equipped with gaseous sensor layers with digital
readout is near perfect for "Particle Flow Algorithm" approach, since it is
homogeneous over large surfaces, robust, cost efficient, easily segmentable to
any readout pad dimension and size and almost insensitive to neutrons. The
response of a finely segmented digital calorimeter is characterized by track
efficiency and multiplicity. Monte Carlo (MC) programs such as GEANT4 simulate
with high precision the energy deposited by particles. The sensor and
electronic response associated to a pad are calculated in a separate
"digitization" process. We developed a general method for simulating the pad
response, a digitization, reproducing efficiency and multiplicity, using the
spatial information from a simulation done at higher granularity. The
digitization method proposed here has been applied to gaseous detectors
including Glass Resistive Plate Chambers (GRPC) and MicroMegas. Validating the
method on test beam data, experimental observables such as efficiency,
multiplicity and mean number of hits at different thresholds have been
reproduced with high precision.Comment: Proceeding for MPGD 201
Electron-Phonon Interactions for Optical Phonon Modes in Few-Layer Graphene
We present a first-principles study of the electron-phonon (e-ph)
interactions and their contributions to the linewidths for the optical phonon
modes at and K in one to three-layer graphene. It is found that due to
the interlayer coupling and the stacking geometry, the high-frequency optical
phonon modes in few-layer graphene couple with different valence and conduction
bands, giving rise to different e-ph interaction strengths for these modes.
Some of the multilayer optical modes derived from the - mode of
monolayer graphene exhibit slightly higher frequencies and much reduced
linewidths. In addition, the linewidths of K- related modes in
multilayers depend on the stacking pattern and decrease with increasing layer
numbers.Comment: 6 pages,5 figures, submitted to PR
Correlation between electrons and vortices in quantum dots
Exact many-body wave functions for quantum dots containing up to four
interacting electrons are computed and we investigated the distribution of the
wave function nodes, also called vortices. For this purpose, we evaluate the
reduced wave function by fixing the positions of all but one electron and
determine the locations of its zeros. We find that the zeros are strongly
correlated with respect to each other and with respect to the position of the
electrons and formulate rules describing their distribution. No multiple zeros
are found, i.e. vortices with vorticity larger than one. Our exact calculations
are compared to results extracted from the recently proposed rotating electron
molecule (REM) wave functions
Energy autonomous wireless sensing system enabled by energy generated during human walking
This is the final version of the article. Available from the publisher via the DOI in this record.PowerMEMS 2016,December 6 – 9, 2016.
The 16th International Conference on
Micro and Nanotechnology for Power Generation
and Energy Conversion Applications, Paris, FranceRecently, there has been a huge amount of work devoted to wearable energy harvesting (WEH) in a bid to establish energy autonomous wireless sensing systems for a range of health monitoring applications. However, limited work has been performed to implement and test such systems in real-world settings. This paper reports the development and real-world characterisation of a magnetically plucked wearable knee-joint energy harvester (Mag-WKEH) powered wireless sensing system, which integrates our latest research progresses in WEH, power conditioning and wireless sensing to achieve high energy efficiency. Experimental results demonstrate that with walking speeds of 3~7 km/h, the Mag-WKEH generates average power of 1.9~4.5 mW with unnoticeable impact on the wearer and is able to power the wireless sensor node (WSN) with three sensors to work at duty cycles of 6.6%~13%. In each active period of 2 s, the WSN is able to measure and transmit 482 readings to the base stationThe authors gratefully acknowledge the financial support from the EPSRC through project
EP/K017950/2
Relations Among Universal Equations For Gromov-Witten Invariants
In this paper, we study relations among known universal equations for
Gromov-Witten invariants at genus 1 and 2.Comment: LaTex file, 13 page
Effect of electron-electron scattering on spin dephasing in a high-mobility low-density twodimensional electron gas
Utilizing time-resolved Kerr rotation techniques, we have investigated the
spin dynamics of a high mobility, low density two dimensional electron gas in a
GaAs/Al0:35Ga0:65As heterostructure in dependence on temperature from 1.5 K to
30 K. It is found that the spin relaxation/dephasing time under a magnetic
field of 0.5 T exhibits a maximum of 3.12 ns around 14 K, superimposed on an
increasing background with rising temperature. The appearance of the maximum is
ascribed to that at the temperature where the crossover from the degenerate to
the nondegenerate regime takes place, electron-electron Coulomb scattering
becomes strongest, and thus inhomogeneous precession broadening due to
D'yakonov-Perel'(DP) mechanism becomes weakest. These results agree with the
recent theoretical predictions [Zhou et al., PRB 75, 045305 (2007)], verifying
the importance of electron-electron Coulomb scattering to electron spin
relaxation/dephasing.Comment: 4 pages, 2 figure
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