1,759 research outputs found
PYTHIA hadronization process tuning in the GENIE neutrino interaction generator
9 pages, 7 figures, proceedings of the CETUP*-Workshop on Neutrino Interactions, July 22-31, 2014 at Lead/Dead Wood, South Dakota, USA9 pages, 7 figures, proceedings of the CETUP*-Workshop on Neutrino Interactions, July 22-31, 2014 at Lead/Dead Wood, South Dakota, USAv1: 9 pages, 7 figures, proceedings of the CETUP*-Workshop on Neutrino Interactions, July 22-31, 2014 at Lead/Dead Wood, South Dakota, USA. v2: 15 pages, 8 figures, 1 table, will be published by Journal of Physics G: Nuclear and Particle Physics (IoP
Diffusing-wave spectroscopy of nonergodic media
We introduce an elegant method which allows the application of diffusing-wave
spectroscopy (DWS) to nonergodic, solid-like samples. The method is based on
the idea that light transmitted through a sandwich of two turbid cells can be
considered ergodic even though only the second cell is ergodic. If absorption
and/or leakage of light take place at the interface between the cells, we
establish a so-called "multiplication rule", which relates the intensity
autocorrelation function of light transmitted through the double-cell sandwich
to the autocorrelation functions of individual cells by a simple
multiplication. To test the proposed method, we perform a series of DWS
experiments using colloidal gels as model nonergodic media. Our experimental
data are consistent with the theoretical predictions, allowing quantitative
characterization of nonergodic media and demonstrating the validity of the
proposed technique.Comment: RevTeX, 12 pages, 6 figures. Accepted for publication in Phys. Rev.
Upper limits for a narrow resonance in the reaction p + p -> K^+ + (Lambda p)
The reaction pp -> K^+ + (Lambda p) has been measured at T_p = 1.953 GeV and
\Theta = 0 deg with a high missing mass resolution in order to study the Lambda
p final state interaction. Narrow S = -1 resonances predicted by bag model
calculations are not visible in the missing mass spectrum. Small structures
observed in a previous experiment are not confirmed. Upper limits for the
production cross section of a narrow resonance are deduced for missing masses
between 2058 and 2105 MeV/c^2.Comment: 8 pages, 5 figure
Chain governance, sector policies and economic sustainability in cocoa; A comparative analysis of Ghana, Côte d'Ivoire, and Ecuador
Fast Photon Detection for Particle Identification with COMPASS RICH-1
Particle identification at high rates is an important challenge for many
current and future high-energy physics experiments. The upgrade of the COMPASS
RICH-1 detector requires a new technique for Cherenkov photon detection at
count rates of several per channel in the central detector region, and a
read-out system allowing for trigger rates of up to 100 kHz. To cope with these
requirements, the photon detectors in the central region have been replaced
with the detection system described in this paper. In the peripheral regions,
the existing multi-wire proportional chambers with CsI photocathode are now
read out via a new system employing APV pre-amplifiers and flash ADC chips. The
new detection system consists of multi-anode photomultiplier tubes (MAPMT) and
fast read-out electronics based on the MAD4 discriminator and the F1-TDC chip.
The RICH-1 is in operation in its upgraded version for the 2006 CERN SPS run.
We present the photon detection design, constructive aspects and the first
Cherenkov light in the detector.Comment: Proceedings of the Imaging 2006 conference, Stockholm, Sweden, 27-30
June 2006, 5 pages, 6 figures, to appear in NIM A; corrected typo in caption
of Fig.
Target and beam-target spin asymmetries in exclusive pion electroproduction for Q2>1GeV2 . I. ep→eπ+n
Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive
Ï€
+
electroproduction reaction
γ
∗
p
→
n
Ï€
+
. The results were obtained from scattering of 6-GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The kinematic range covered is
1.1
<
W
<
3
GeV and
1
<
Q
2
<
6
GeV
2
. Results were obtained for about 6000 bins in
W
,
Â
Q
2
,
Â
cos
(
θ
∗
)
, and
Ï•
∗
. Except at forward angles, very large target-spin asymmetries are observed over the entire
W
region. Reasonable agreement is found with phenomenological fits to previous data for
W
<
1.6
GeV, but very large differences are seen at higher values of
W
. A generalized parton distributions (GPD)-based model is in poor agreement with the data. When combined with cross-sectional measurements, the present results provide powerful constraints on nucleon resonance amplitudes at moderate and large values of
Q
2
, for resonances with masses as high as 2.4 GeV
Towards a resolution of the proton form factor problem: new electron and positron scattering data
There is a significant discrepancy between the values of the proton electric
form factor, , extracted using unpolarized and polarized electron
scattering. Calculations predict that small two-photon exchange (TPE)
contributions can significantly affect the extraction of from the
unpolarized electron-proton cross sections. We determined the TPE contribution
by measuring the ratio of positron-proton to electron-proton elastic scattering
cross sections using a simultaneous, tertiary electron-positron beam incident
on a liquid hydrogen target and detecting the scattered particles in the
Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide
range in virtual photon polarization () and momentum transfer
() simultaneously, as well as to cancel luminosity-related systematic
errors. The cross section ratio increases with decreasing at . This measurement is consistent with the size of the form
factor discrepancy at GeV and with hadronic calculations
including nucleon and intermediate states, which have been shown to
resolve the discrepancy up to GeV.Comment: 6 pages, 4 figures, submitted to PR
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