486 research outputs found
Extracting the depolarization coefficient D_NN from data measured with a full acceptance detector
The spin transfer from vertically polarized beam protons to Lambda or Sigma
hyperons of the associated strangeness production pp -> pK Lambda (Sigma) is
described with the depolarization coefficient D_NN. As the polarization of the
hyperons is determined by their weak decays, detectors, which have a large
acceptance for the decay particles, are needed. In this paper a formula is
derived, which describes the depolarization coefficient D_NN by count rates of
a 4 pi detector. It is shown, that formulas, which are given in publications
for detectors with restricted acceptance, are specific cases of this formula
for a 4 pi detector.Comment: Accepted for publication by Nuclear Instruments and Methods in
Physics Research Section
Mikrostruktura wygrzewanych pokryć cynkowych typu galfan na podłożu stalowym
The commercially available Galfan coating containing 5-7wt.% of Al deposited on the low carbon steel substrate by
hot dipping has been examined with respect to the microstructure of the coating/substrate interface area. The application of
several experimental techniques (SEM/EDS, XRD, TEM/AEM/EDS/ED) allowed demonstrating the two-phase structure of the
alloy coating in non-treated, commercially available Galfan samples: Zn-rich pre-eutectoid phase grains are surrounded by
lamellar eutectics of -Al and -Zn. The transition layer between the alloy coating and steel substrate with the considerably
higher Al content (SEM/EDS, TEM/EDS) has been found in both non-treated and annealed samples (600oC/5 minutes). Only
the monoclinic FeAl3Znx phase however was revealed in the annealed sample (TEM/electron diffraction) remaining uncertain
the presence of the orthorhombic Fe2Al5Znx phase, reported by several authors
One-Particle Measurement of the Antiproton Magnetic Moment
\DeclareRobustCommand{\pbar}{\HepAntiParticle{p}{}{}\xspace}
\DeclareRobustCommand{\p}{\HepParticle{p}{}{}\xspace}
\DeclareRobustCommand{\mup}{{}{}\xspace}
\DeclareRobustCommand{\mupbar}{\mu_{\pbar}{}{}\xspace}
\DeclareRobustCommand{\muN}{{}{}\xspace
For the first time a single trapped \pbar is used to measure the \pbar
magnetic moment {\bm\mu}_{\pbar}. The moment {\bm\mu}_{\pbar} = \mu_{\pbar}
{\bm S}/(\hbar/2) is given in terms of its spin and the nuclear
magneton (\muN) by \mu_{\pbar}/\mu_N = -2.792\,845 \pm 0.000\,012. The 4.4
parts per million (ppm) uncertainty is 680 times smaller than previously
realized. Comparing to the proton moment measured using the same method and
trap electrodes gives \mu_{\pbar}/\mu_p = -1.000\,000 \pm 0.000\,005 to 5
ppm, for a proton moment ,
consistent with the prediction of the CPT theorem.Comment: 4 pages, 4 figures. arXiv admin note: substantial text overlap with
arXiv:1201.303
Determination of the eta'-proton scattering length in free space
Taking advantage of both the high mass resolution of the COSY-11 detector and
the high energy resolution of the low-emittance proton-beam of the Cooler
Synchrotron COSY we determine the excitation function for the pp --> pp eta'
reaction close-to-threshold. Combining these data with previous results we
extract the scattering length for the eta'-proton potential in free space to be
Re(a_{p eta'}) = 0+-0.43 fm and Im(a_{p eta'}) = 0.37(+0.40)(-0.16) fm.Comment: 5 pages, 3 figures, accepted for publication in Phys. Rev. Let
Studies of dust from JET with the ITER-Like Wall: Composition and internal structure
Results are presented for the dust survey performed at JET after the second experimental campaign with the ITER-Like Wall: 2013–2014. Samples were collected on adhesive stickers from several different posi- tions in the divertor both on the tiles and on the divertor carrier. Brittle dust-forming deposits on test mirrors from the inner divertor wall were also studied. Comprehensive characterization accomplished by a wide range of high-resolution microscopy techniques, including focused ion beam, has led to the iden- tification of several classes of particles: (i) beryllium flakes originating either from the Be coatings from the inner wall cladding or Be-rich mixed co-deposits resulting from material migration; (ii) beryllium droplets and splashes; (iii) tungsten and nickel-rich (from Inconel) droplets; (iv) mixed material layers with a various content of small (8–200 nm) W-Mo and Ni-based debris. A significant content of nitrogen from plasma edge cooling has been identified in all types of co-deposits. A comparison between particles collected after the first and second experimental campaign is also presented and discussed.EURATOM 63305
High precision measurement of the associated strangeness production in proton proton interactions
A new high precision measurement of the reaction pp -> pK+Lambda at a beam
momentum of 2.95 GeV/c with more than 200,000 analyzed events allows a detailed
analysis of differential observables and their inter-dependencies. Correlations
of the angular distributions with momenta are examined. The invariant mass
distributions are compared for different regions in the Dalitz plots. The cusp
structure at the N Sigma threshold is described with the Flatt\'e formalism and
its variation in the Dalitz plot is analyzed.Comment: accepted for publication in Eur. Phys. J.
First Model-Independent Measurement of the Spin Triplet Scattering Length from Final State Interaction in the Reaction
The reaction has been measured with the
COSY-TOF detector at a beam momentum of . The polarized
proton beam enables the measurement of the beam analyzing power by the
asymmetry of the produced kaon (). This observable allows the
spin triplet scattering length to be extracted for the first time
model independently from the final-state interaction in the reaction. The
obtained value is . This value is
compatible with theoretical predictions and results from model-dependent
analyses.Comment: Revised version as accepted for publication in PR
Determination of the total width of the eta' meson
Taking advantage of both the low-emittance proton-beam of the Cooler
Synchrotron COSY and the high momentum precision of the COSY-11 detector
system, the mass distribution of the eta' meson was measured with a resolution
of 0.33 MeV/c^2 (FWHM), improving the experimental mass resolution by almost an
order of magnitude with respect to previous results. Based on the sample of
more than 2300 reconstructed pp --> pp eta' events the total width of the eta'
meson was determined to be 0.226 +- 0.017(stat.) +- 0.014(syst.) MeV/c^2.Comment: 4 pages, 4 figure
General thoughts to the Kaon pair production in the threshold region
Simple--minded thoughts about the cross sections for the reactions
pp-->ppK+K- and pp-->ppK0K0 are presented, which certainly do not account for
the complex coupled channel problem but rather provide some ideas into the
mutual reaction dynamics.Comment: Talk given at 9th International Workshop on Meson Production,
Properties and Interaction, Cracow, Poland, 9-13 June 2006. 3 pages, 2
figure
Search for the 3He-eta bound state at COSY-11
We have measured excitation function for dp -> ppp_pi- reaction near the eta
production threshold. We observe an enhancement of the counting rate above the
threshold which can originate from the production of the eta meson in the
reaction dp -> 3He eta and its subsequent absorption on neutron in the 3He
nucleus leading to creation of the p_pi- pair.Comment: Presented at 10th International Workshop on Meson Production,
Properties and Interaction (MESON 2008), Cracow, Poland, 6 - 10 June 2008, 4
pages, 4 figures,references adde
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