4,311 research outputs found
Double transverse spin asymmetry in the Drell-Yan process from Sivers functions
We show that the transverse double spin asymmetry (DSA) in the Drell-Yan
process contributed only from the Sivers functions can be picked out by the
weighting function
.
The asymmetry is proportional to the product of two Sivers functions from each
hadron . Using two sets of Sivers
functions extracted from the semi-inclusive deeply elastic scattering data at
HERMES, we estimate this asymmetry in the
Drell-Yan process which is possible to be performed in HESR at GSI. The
prediction of DSA in the Drell-Yan process contributed by the function
g_{1T}(x,\Vec k_T^2), which can be extracted by the weighting function
,
is also given at GSI.Comment: 6 latex pages, 2 figures, to appear in PR
Performance of the EUDET-type beam telescopes
Test beam measurements at the test beam facilities of DESY have been
conducted to characterise the performance of the EUDET-type beam telescopes
originally developed within the EUDET project. The beam telescopes are equipped
with six sensor planes using MIMOSA26 monolithic active pixel devices. A
programmable Trigger Logic Unit provides trigger logic and time stamp
information on particle passage. Both data acquisition framework and offline
reconstruction software packages are available. User devices are easily
integrable into the data acquisition framework via predefined interfaces.
The biased residual distribution is studied as a function of the beam energy,
plane spacing and sensor threshold. Its standard deviation at the two centre
pixel planes using all six planes for tracking in a 6\,GeV
electron/positron-beam is measured to be
(2.88\,\pm\,0.08)\,\upmu\meter.Iterative track fits using the formalism of
General Broken Lines are performed to estimate the intrinsic resolution of the
individual pixel planes. The mean intrinsic resolution over the six sensors
used is found to be (3.24\,\pm\,0.09)\,\upmu\meter.With a 5\,GeV
electron/positron beam, the track resolution halfway between the two inner
pixel planes using an equidistant plane spacing of 20\,mm is estimated to
(1.83\,\pm\,0.03)\,\upmu\meter assuming the measured intrinsic resolution.
Towards lower beam energies the track resolution deteriorates due to increasing
multiple scattering. Threshold studies show an optimal working point of the
MIMOSA26 sensors at a sensor threshold of between five and six times their RMS
noise. Measurements at different plane spacings are used to calibrate the
amount of multiple scattering in the material traversed and allow for
corrections to the predicted angular scattering for electron beams
Development of ultra-light pixelated ladders for an ILC vertex detector
The development of ultra-light pixelated ladders is motivated by the
requirements of the ILD vertex detector at ILC. This paper summarizes three
projects related to system integration. The PLUME project tackles the issue of
assembling double-sided ladders. The SERWIETE project deals with a more
innovative concept and consists in making single-sided unsupported ladders
embedded in an extra thin plastic enveloppe. AIDA, the last project, aims at
building a framework reproducing the experimental running conditions where sets
of ladders could be tested
photoluminescence of a single quantum emitter in a strongly inhomogeneous chemical environment
A comprehensive photoluminescence study of defect centers in single SiO2 nanoparticles provides new insight into the complex photo-physics of single quantum emitters embedded into a random chemical environment
Are there approximate relations among transverse momentum dependent distribution functions?
Certain exact relations among transverse momentum dependent parton
distribution functions due to QCD equations of motion turn into approximate
ones upon the neglect of pure twist-3 terms. On the basis of available data
from HERMES we test the practical usefulness of one such
``Wandzura-Wilczek-type approximation'', namely of that connecting
h_{1L}^{\perp(1)a}(x) to h_L^a(x), and discuss how it can be further tested by
future CLAS and COMPASS data.Comment: 9 pages, 3 figure
Sivers effect in Drell Yan at RHIC
On the basis of a fit to the Sivers effect in deep-inelastic scattering, we
make predictions for single-spin asymmetries in the Drell-Yan process at RHIC.Comment: 10 pages, 7 figures, 1 table. v2: References and comments added,
minor correction
Regular and Irregular States in Generic Systems
In this work we present the results of a numerical and semiclassical analysis
of high lying states in a Hamiltonian system, whose classical mechanics is of a
generic, mixed type, where the energy surface is split into regions of regular
and chaotic motion. As predicted by the principle of uniform semiclassical
condensation (PUSC), when the effective tends to 0, each state can be
classified as regular or irregular. We were able to semiclassically reproduce
individual regular states by the EBK torus quantization, for which we devise a
new approach, while for the irregular ones we found the semiclassical
prediction of their autocorrelation function, in a good agreement with
numerics. We also looked at the low lying states to better understand the onset
of semiclassical behaviour.Comment: 25 pages, 14 figures (as .GIF files), high quality figures available
upon reques
Effect of crystallographic anisotropy on the resistance switching phenomenon in perovskites
Resistance switching effects in metal/perovskite contacts based on epitaxial
c-axis oriented Y-Ba-Cu-O (YBCO) thin films with different crystallographic
orientations have been studied. Three types of Ag/YBCO junctions with the
contact restricted to (i) c-axis direction, (ii) ab-plane direction, and (iii)
both were designed and fabricated, and their current-voltage characteristics
have been measured. The type (i) junctions exhibited conventional bipolar
resistance switching behavior, whereas in other two types the low-resistance
state was unsteady and their resistance quickly relaxed to the initial
high-resistance state. Physical mechanism based on the oxygen diffusion
scenario, explaining such behavior, is discussed.Comment: The final version was published in Journal of Applied Physics (2012
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