7,981 research outputs found
MINERvA neutrino detector response measured with test beam data
The MINERvA collaboration operated a scaled-down replica of the solid
scintillator tracking and sampling calorimeter regions of the MINERvA detector
in a hadron test beam at the Fermilab Test Beam Facility. This article reports
measurements with samples of protons, pions, and electrons from 0.35 to 2.0
GeV/c momentum. The calorimetric response to protons, pions, and electrons are
obtained from these data. A measurement of the parameter in Birks' law and an
estimate of the tracking efficiency are extracted from the proton sample.
Overall the data are well described by a Geant4-based Monte Carlo simulation of
the detector and particle interactions with agreements better than 4%, though
some features of the data are not precisely modeled. These measurements are
used to tune the MINERvA detector simulation and evaluate systematic
uncertainties in support of the MINERvA neutrino cross section measurement
program.Comment: as accepted by NIM
Breaking the challenge of signal integrity using time-domain spoof surface plasmon polaritons
In modern integrated circuits and wireless communication systems/devices,
three key features need to be solved simultaneously to reach higher performance
and more compact size: signal integrity, interference suppression, and
miniaturization. However, the above-mentioned requests are almost contradictory
using the traditional techniques. To overcome this challenge, here we propose
time-domain spoof surface plasmon polaritons (SPPs) as the carrier of signals.
By designing a special plasmonic waveguide constructed by printing two narrow
corrugated metallic strips on the top and bottom surfaces of a dielectric
substrate with mirror symmetry, we show that spoof SPPs are supported from very
low frequency to the cutoff frequency with strong subwavelength effects, which
can be converted to the time-domain SPPs. When two such plasmonic waveguides
are tightly packed with deep-subwavelength separation, which commonly happens
in the integrated circuits and wireless communications due to limited space, we
demonstrate theoretically and experimentally that SPP signals on such two
plasmonic waveguides have better propagation performance and much less mutual
coupling than the conventional signals on two traditional microstrip lines with
the same size and separation. Hence the proposed method can achieve significant
interference suppression in very compact space, providing a potential solution
to break the challenge of signal integrity
Surface wave control for large arrays of microwave kinetic inductance detectors
Large ultra-sensitive detector arrays are needed for present and future
observatories for far infra-red, submillimeter wave (THz), and millimeter wave
astronomy. With increasing array size, it is increasingly important to control
stray radiation inside the detector chips themselves, the surface wave. We
demonstrate this effect with focal plane arrays of 880 lens-antenna coupled
Microwave Kinetic Inductance Detectors (MKIDs). Presented here are near field
measurements of the MKID optical response versus the position on the array of a
reimaged optical source. We demonstrate that the optical response of a detector
in these arrays saturates off-pixel at the dB level compared to the
peak pixel response. The result is that the power detected from a point source
at the pixel position is almost identical to the stray response integrated over
the chip area. With such a contribution, it would be impossible to measure
extended sources, while the point source sensitivity is degraded due to an
increase of the stray loading. However, we show that by incorporating an
on-chip stray light absorber, the surface wave contribution is reduced by a
factor 10. With the on-chip stray light absorber the point source response
is close to simulations down to the dB level, the simulation based on
an ideal Gaussian illumination of the optics. In addition, as a crosscheck we
show that the extended source response of a single pixel in the array with the
absorbing grid is in agreement with the integral of the point source
measurements.Comment: accepted for publication in IEEE Transactions on Terahertz Science
and Technolog
Game theoretic aspects of distributed spectral coordination with application to DSL networks
In this paper we use game theoretic techniques to study the value of
cooperation in distributed spectrum management problems. We show that the
celebrated iterative water-filling algorithm is subject to the prisoner's
dilemma and therefore can lead to severe degradation of the achievable rate
region in an interference channel environment. We also provide thorough
analysis of a simple two bands near-far situation where we are able to provide
closed form tight bounds on the rate region of both fixed margin iterative
water filling (FM-IWF) and dynamic frequency division multiplexing (DFDM)
methods. This is the only case where such analytic expressions are known and
all previous studies included only simulated results of the rate region. We
then propose an alternative algorithm that alleviates some of the drawbacks of
the IWF algorithm in near-far scenarios relevant to DSL access networks. We
also provide experimental analysis based on measured DSL channels of both
algorithms as well as the centralized optimum spectrum management
Performance analysis of d-dimensional quantum cryptography under state-dependent diffraction
Standard protocols for quantum key distribution (QKD) require that the sender
be able to transmit in two or more mutually unbiased bases. Here, we analyze
the extent to which the performance of QKD is degraded by diffraction effects
that become relevant for long propagation distances and limited sizes of
apertures. In such a scenario, different states experience different amounts of
diffraction, leading to state-dependent loss and phase acquisition, causing an
increased error rate and security loophole at the receiver. To solve this
problem, we propose a pre-compensation protocol based on pre-shaping the
transverse structure of quantum states. We demonstrate, both theoretically and
experimentally, that when performing QKD over a link with known,
symbol-dependent loss and phase shift, the performance of QKD will be better if
we intentionally increase the loss of certain symbols to make the loss and
phase shift of all states same. Our results show that the pre-compensated
protocol can significantly reduce the error rate induced by state-dependent
diffraction and thereby improve the secure key rate of QKD systems without
sacrificing the security.Comment: 10 pages, 6 figure
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