2,679 research outputs found
Q^2 Evolution of the Neutron Spin Structure Moments using a ^3He Target
We have measured the spin structure functions g_1 and g_2 of ^3He in a double-spin experiment by inclusively scattering polarized electrons at energies ranging from 0.862 to 5.058 GeV off a polarized ^3He target at a 15.5° scattering angle. Excitation energies covered the resonance and the onset of the deep inelastic regions. We have determined for the first time the Q^2 evolution of Γ_1(Q^2)=∫_0^1g_1(x,Q^2)dx, Γ_2(Q^2)=∫_0^1g_2(x,Q^2)dx, and d_2(Q^2)=∫_0^1x^2[2g_1(x,Q^2)+3g_2(x,Q^2)]dx for the neutron in the range 0.1 ≤ Q^2 ≤0.9  GeV^2 with good precision. Γ_1(Q^2) displays a smooth variation from high to low Q^2. The Burkhardt-Cottingham sum rule holds within uncertainties and d_2 is nonzero over the measured range
Two proposals for testing quantum contextuality of continuous-variable states
We investigate the violation of non-contextuality by a class of continuous
variable states, including variations of entangled coherent states (ECS's) and
a two-mode continuous superposition of coherent states. We generalise the
Kochen-Specker (KS) inequality discussed in A. Cabello, Phys. Rev. Lett. {\bf
101}, 210401 (2008) by using effective bidimensional observables implemented
through physical operations acting on continuous variable states, in a way
similar to an approach to the falsification of Bell-CHSH inequalities put
forward recently. We test for state-independent violation of KS inequalities
under variable degrees of state entanglement and mixedness. We then demonstrate
theoretically the violation of a KS inequality for any two-mode state by using
pseudo-spin observables and a generalized quasi-probability function.Comment: 7 pages, 2 figures, RevTeX
Programming Protocol-Independent Packet Processors
P4 is a high-level language for programming protocol-independent packet
processors. P4 works in conjunction with SDN control protocols like OpenFlow.
In its current form, OpenFlow explicitly specifies protocol headers on which it
operates. This set has grown from 12 to 41 fields in a few years, increasing
the complexity of the specification while still not providing the flexibility
to add new headers. In this paper we propose P4 as a strawman proposal for how
OpenFlow should evolve in the future. We have three goals: (1)
Reconfigurability in the field: Programmers should be able to change the way
switches process packets once they are deployed. (2) Protocol independence:
Switches should not be tied to any specific network protocols. (3) Target
independence: Programmers should be able to describe packet-processing
functionality independently of the specifics of the underlying hardware. As an
example, we describe how to use P4 to configure a switch to add a new
hierarchical label
Observation of Parity Nonconservation in Møller Scattering
We report a measurement of the parity-violating asymmetry in fixed target electron-electron (Møller) scattering: A_(PV) = [-175 ± 30(stat)± 20(syst)] X 10^(-9). This first direct observation of parity nonconservation in Møller scattering leads to a measurement of the electron’s weak charge at low energy Q^e_W = -0:053 ± 0:011. This is consistent with the standard model expectation at the current level of precision: sin^2θ_W = (M_Z)_(MS) = 0:2293 ± 0:0024(stat) ± 0:0016(syst) ± 0:0006(theory)
Atomically precise lateral modulation of a two-dimensional electron liquid in anatase TiO2 thin films
Engineering the electronic band structure of two-dimensional electron liquids
(2DELs) confined at the surface or interface of transition metal oxides is key
to unlocking their full potential. Here we describe a new approach to tailoring
the electronic structure of an oxide surface 2DEL demonstrating the lateral
modulation of electronic states with atomic scale precision on an unprecedented
length scale comparable to the Fermi wavelength. To this end, we use pulsed
laser deposition to grow anatase TiO2 films terminated by a (1 x 4) in-plane
surface reconstruction. Employing photo-stimulated chemical surface doping we
induce 2DELs with tunable carrier densities that are confined within a few TiO2
layers below the surface. Subsequent in-situ angle resolved photoemission
experiments demonstrate that the (1 x 4) surface reconstruction provides a
periodic lateral perturbation of the electron liquid. This causes strong
backfolding of the electronic bands, opening of unidirectional gaps and a
saddle point singularity in the density of states near the chemical potential
Coexistence of supravalvular aortic stenosis and osteogenesis imperfecta.
A 54 year old woman was admitted for cardiac catheterisation. She had-been attending the outpatient clinic since 1975, with regular review. She had diagnoses of type I osteogenesis imperfecta, and of supravalvular aortic stenosis. Osteogenesis imperfecta was diagnosed in early life on clinical grounds including the presence of blue sclerae and the occurrence of several bone fractures secondary to minimal trauma. A number of family members have been diagnosed with the same condition (figure 1-family pedigree). The supravalvular aortic stenosis was not diagnosed until later. She was initially referred to the cardiology clinic for further evaluation following the discovery of a systolic murmu
Neutron Calibration Sources in the Daya Bay Experiment
We describe the design and construction of the low rate neutron calibration
sources used in the Daya Bay Reactor Anti-neutrino Experiment. Such sources are
free of correlated gamma-neutron emission, which is essential in minimizing
induced background in the anti-neutrino detector. The design characteristics
have been validated in the Daya Bay anti-neutrino detector.Comment: 13 pages, 7 figure
The Cryogenic Target for the G Experiment at Jefferson Lab
A cryogenic horizontal single loop target has been designed, built, tested
and operated for the G experiment in Hall C at Jefferson Lab. The target
cell is 20 cm long, the loop volume is 6.5 l and the target operates with the
cryogenic pump fully immersed in the fluid. The target has been designed to
operate at 30 Hz rotational pump speed with either liquid hydrogen or liquid
deuterium. The high power heat exchanger is able to remove 1000 W of heat from
the liquid hydrogen, while the nominal electron beam with current of 40 A
and energy of 3 GeV deposits about 320 W of heat into the liquid. The increase
in the systematic uncertainty due to the liquid hydrogen target is negligible
on the scale of a parity violation experiment. The global normalized yield
reduction for 40 A beam is about 1.5 % and the target density fluctuations
contribute less than 238 ppm (parts per million) to the total asymmetry width,
typically about 1200 ppm, in a Q bin.Comment: 27 pages, 14 figure
A side-by-side comparison of Daya Bay antineutrino detectors
The Daya Bay Reactor Neutrino Experiment is designed to determine precisely the neutrino mixing angle θ_(13) with a sensitivity better than 0.01 in the parameter sin^22θ_(13) at the 90% confidence level. To achieve this goal, the collaboration will build eight functionally identical antineutrino detectors. The first two detectors have been constructed, installed and commissioned in Experimental Hall 1, with steady data-taking beginning September 23, 2011. A comparison of the data collected over the subsequent three months indicates that the detectors are functionally identical, and that detector-related systematic uncertainties are smaller than requirements
An Energy Feedback System for the MIT/Bates Linear Accelerator
We report the development and implementation of an energy feedback system for
the MIT/Bates Linear Accelerator Center. General requirements of the system are
described, as are the specific requirements, features, and components of the
system unique to its implementation at the Bates Laboratory. We demonstrate
that with the system in operation, energy fluctuations correlated with the 60
Hz line voltage and with drifts of thermal origin are reduced by an order of
magnitude
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