4,275 research outputs found
Dispersively detected Pauli Spin-Blockade in a Silicon Nanowire Field-Effect Transistor
We report the dispersive readout of the spin state of a double quantum dot
formed at the corner states of a silicon nanowire field-effect transistor. Two
face-to-face top-gate electrodes allow us to independently tune the charge
occupation of the quantum dot system down to the few-electron limit. We measure
the charge stability of the double quantum dot in DC transport as well as
dispersively via in-situ gate-based radio frequency reflectometry, where one
top-gate electrode is connected to a resonator. The latter removes the need for
external charge sensors in quantum computing architectures and provides a
compact way to readout the dispersive shift caused by changes in the quantum
capacitance during interdot charge transitions. Here, we observe Pauli
spin-blockade in the high-frequency response of the circuit at finite magnetic
fields between singlet and triplet states. The blockade is lifted at higher
magnetic fields when intra-dot triplet states become the ground state
configuration. A lineshape analysis of the dispersive phase shift reveals
furthermore an intradot valley-orbit splitting of 145 eV.
Our results open up the possibility to operate compact CMOS technology as a
singlet-triplet qubit and make split-gate silicon nanowire architectures an
ideal candidate for the study of spin dynamics
A review of the catfish genus Pterocryptis (Siluridae) in Vietnam, with the description of two new species
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73958/1/j.1095-8649.2001.tb02367.x.pd
High-pT pi^zero Production with Respect to the Reaction Plane in Au + Au Collisions at sqrt(s_NN) = 200 GeV
Measurements of the azimuthal anisotropy of high-\pT neutral pion neutral
pion production in Au+Au collisions at sqrt(s_NN) = 200 GeV by the PHENIX
experiment are presented. The data included in this paper were collected during
the 2004 RHIC running period and represent approximately an order of magnitude
increase in the number of analyzed events relative to previously published
results. Azimuthal angle distributions of pi^0s detected in the PHENIX
electromagnetic calorimeters are measured relative to the reaction plane
determined event-by-event using the forward and backward beam-beam counters.
Amplitudes of the second Fourier component (v_2) of the angular distributions
are presented as a function of pi^0 transverse momentum p_T for different bins
in collision centrality. Measured reaction plane dependent pi^0 yields are used
to determine the azimuthal dependence of the pi^0 suppression as a function of
p_T, R_AA (Delta phi,p_T). A jet-quenching motivated geometric analysis is
presented that attempts to simultaneously describe the centrality dependence
and reaction plane angle dependence of the pi^0 suppression in terms of the
path lengths of hypothetical parent partons in the medium. This set of results
allows for a detailed examination of the influence of geometry in the collision
region, and of the interplay between collective flow and jet-quenching effects
along the azimuthal axis.Comment: 344 authors, 35 pages text, RevTeX-4, 24 figures, 8 tables. Submitted
to Physical Review
Journal Staff
We present the first measurements of the differential cross section d sigma/dp(T)(gamma) for the production of an isolated photon in association with at least two b-quark jets. The measurements consider photons with rapidities vertical bar y(gamma)vertical bar < 1.0 and transverse momenta 30 < p(T)(gamma) < 200 GeV. The b-quark jets are required to have p(T)(jet) > 15 GeVand vertical bar y(jet)vertical bar < 1.5. The ratio of differential production cross sections for gamma + 2 b-jets to gamma + b-jet as a function of p(T)(gamma) is also presented. The results are based on the proton-antiproton collision data at root s = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. The measured cross sections and their ratios are compared to the next- to- leading order perturbative QCD calculations as well as predictions based on the k(T)- factorization approach and those from the sherpa and pythia Monte Carlo event generators
Transverse-energy distributions at midrapidity in , Au, and AuAu collisions at --200~GeV and implications for particle-production models
Measurements of the midrapidity transverse energy distribution, d\Et/d\eta,
are presented for , Au, and AuAu collisions at
GeV and additionally for AuAu collisions at
and 130 GeV. The d\Et/d\eta distributions are first
compared with the number of nucleon participants , number of
binary collisions , and number of constituent-quark participants
calculated from a Glauber model based on the nuclear geometry. For
AuAu, \mean{d\Et/d\eta}/N_{\rm part} increases with , while
\mean{d\Et/d\eta}/N_{qp} is approximately constant for all three energies.
This indicates that the two component ansatz, , which has been used to represent
distributions, is simply a proxy for , and that the term
does not represent a hard-scattering component in distributions. The
distributions of AuAu and Au are then calculated from
the measured distribution using two models that both reproduce
the AuAu data. However, while the number-of-constituent-quark-participant
model agrees well with the Au data, the additive-quark model does not.Comment: 391 authors, 24 pages, 19 figures, and 15 Tables. Submitted to Phys.
Rev. C. Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are publicly available at
http://www.phenix.bnl.gov/papers.htm
Transverse momentum and centrality dependence of dihadron correlations in Au+Au collisions at sqrt(s_NN)=200 GeV: Jet-quenching and the response of partonic matter
Azimuthal angle \Delta\phi correlations are presented for charged hadrons
from dijets for 0.4 < p_T < 10 GeV/c in Au+Au collisions at sqrt(s_NN) = 200
GeV. With increasing p_T, the away-side distribution evolves from a broad to a
concave shape, then to a convex shape. Comparisons to p+p data suggest that the
away-side can be divided into a partially suppressed "head" region centered at
Delta\phi ~ \pi, and an enhanced "shoulder" region centered at Delta\phi ~ \pi
+/- 1.1. The p_T spectrum for the "head" region softens toward central
collisions, consistent with the onset of jet quenching. The spectral slope for
the "shoulder" region is independent of centrality and trigger p_T, which
offers constraints on energy transport mechanisms and suggests that the
"shoulder" region contains the medium response to energetic jets.Comment: 420 authors from 58 institutions, 6 pages, 4 figures. Submitted to
Physical Review Letters. Plain text data tables for the points plotted in
figures for this and previous PHENIX publications are (or will be) publicly
available at http://www.phenix.bnl.gov/papers.htm
Transverse energy production and charged-particle multiplicity at midrapidity in various systems from to 200 GeV
Measurements of midrapidity charged particle multiplicity distributions,
, and midrapidity transverse-energy distributions,
, are presented for a variety of collision systems and energies.
Included are distributions for AuAu collisions at ,
130, 62.4, 39, 27, 19.6, 14.5, and 7.7 GeV, CuCu collisions at
and 62.4 GeV, CuAu collisions at
GeV, UU collisions at GeV,
Au collisions at GeV, HeAu collisions at
GeV, and collisions at
GeV. Centrality-dependent distributions at midrapidity are presented in terms
of the number of nucleon participants, , and the number of
constituent quark participants, . For all collisions
down to GeV, it is observed that the midrapidity data
are better described by scaling with than scaling with . Also presented are estimates of the Bjorken energy density,
, and the ratio of to ,
the latter of which is seen to be constant as a function of centrality for all
systems.Comment: 706 authors, 32 pages, 20 figures, 34 tables, 2004, 2005, 2008, 2010,
2011, and 2012 data. v2 is version accepted for publication in Phys. Rev.
Particle-species dependent modification of jet-induced correlations in Au+Au collisions at sqrt(s_NN) = 200 GeV
We report PHENIX measurements of the correlation of a trigger hadron at
intermediate transverse momentum (2.5<p_{T,trig}<4 GeV/c), with associated
mesons or baryons at lower p_{T,assoc}, in Au+Au collisions at sqrt(s_NN) = 200
GeV. The jet correlations for both baryons and mesons show similar shape
alterations as a function of centrality, characteristic of strong modification
of the away-side jet. The ratio of jet-associated baryons to mesons for this
jet increases with centrality and p_{T,assoc} and, in the most central
collisions, reaches a value similar to that for inclusive measurements. This
trend is incompatible with in-vacuum fragmentation, but could be due to
jet-like contributions from correlated soft partons which recombine upon
hadronization.Comment: 344 authors, 4 pages text, RevTeX, 4 figures. Submitted to Physical
Review Letters. Plain text data tables for the points plotted in figures for
this and previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Measurement of the semileptonic charge asymmetry in B0 meson mixing with the D0 detector
We present a measurement of the semileptonic mixing asymmetry for B0 mesons,
a^d_{sl}, using two independent decay channels: B0 -> mu+D-X, with D- ->
K+pi-pi-; and B0 -> mu+D*-X, with D*- -> antiD0 pi-, antiD0 -> K+pi- (and
charge conjugate processes). We use a data sample corresponding to 10.4 fb^{-1}
of ppbar collisions at sqrt(s) = 1.96 TeV, collected with the D0 experiment at
the Fermilab Tevatron collider. We extract the charge asymmetries in these two
channels as a function of the visible proper decay length (VPDL) of the B0
meson, correct for detector-related asymmetries using data-driven methods, and
account for dilution from charge-symmetric processes using Monte Carlo
simulation. The final measurement combines four signal VPDL regions for each
channel, yielding a^d_{sl} = [0.68 \pm 0.45 \text{(stat.)} \pm 0.14
\text{(syst.)}]%. This is the single most precise measurement of this
parameter, with uncertainties smaller than the current world average of B
factory measurements.Comment: Version includes minor textual changes following peer review by
journal, most notably the updating of Ref. [21] to reflect the most recent
publicatio
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