255 research outputs found
Skyrmion Lattice in a Doped Semiconductor
We report a comprehensive small angle neutron scattering study (SANS) of the
magnetic phase diagram of the doped semiconductor Fe_{1-x}Co_{x}Si for x=0.2
and 0.25. For magnetic field parallel to the neutron beam we observe a six-fold
intensity pattern under field-cooling, which identifies the A-phase of
Fe_{1-x}Co_{x}Si as a skyrmion lattice. The regime of the skyrmion lattice is
highly hysteretic and extents over a wide temperature range, consistent with
the site disorder of the Fe and Co atoms. Our study identifies Fe_{1-x}Co_{x}Si
is a second material after MnSi in which a skyrmion lattice forms and
establishes that skyrmion lattices may also occur in strongly doped
semiconductors
Strange meson production in Al+Al collisions at 1.9A GeV
The production of K, K and (1020) mesons is studied in Al+Al
collisions at a beam energy of 1.9A GeV which is close or below the production
threshold in NN reactions. Inverse slopes, anisotropy parameters, and total
emission yields of K mesons are obtained. A comparison of the ratio of
kinetic energy distributions of K and K mesons to the HSD transport
model calculations suggests that the inclusion of the in-medium modifications
of kaon properties is necessary to reproduce the ratio. The inverse slope and
total yield of mesons are deduced. The contribution to K production
from meson decays is found to be [17 3 (stat) (syst)]
%. The results are in line with previous K and data obtained for
different colliding systems at similar incident beam energies.Comment: 16 pages, 11 figure
Production of Sigma{\pm}pi?pK+ in p+p reactions at 3.5 GeV beam energy
We study the production of Sigma^+-pi^+-pK^+ particle quartets in p+p
reactions at 3.5 GeV kinetic beam energy. The data were taken with the HADES
experiment at GSI. This report evaluates the contribution of resonances like
Lambda(1405$, Sigma(1385)^0, Lambda(1520), Delta(1232), N^* and K^*0 to the
Sigma^+- pi^-+ p K+ final state. The resulting simulation model is compared to
the experimental data in several angular distributions and it shows itself as
suitable to evaluate the acceptance corrections properly.Comment: 15 pages, 5 figure
Centrality dependence of subthreshold meson production in Ni+Ni collisions at 1.9A GeV
We analysed the meson production in central Ni+Ni collisions at the
beam kinetic energy of 1.93A GeV with the FOPI spectrometer and found the
production probability per event of . This new data point allows for the first time
to inspect the centrality dependence of the subthreshold meson
production in heavy-ion collisions. The rise of meson multiplicity per
event with mean number of participants can be parameterized by the power
function with exponent . The ratio of to
production yields seems not to depend within the experimental
uncertainties on the collision centrality, and the average of measured values
was found to be .Comment: 9 pages, 5 figure
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