76 research outputs found
Optical alignment and orientation of excitons in ensemble of core/shell CdSe/CdS colloidal nanoplatelets
We report on the experimental and theoretical studies of optical alignment
and optical orientation effects in an ensemble of core/shell CdSe/CdS colloidal
nanoplatelets. The dependences of three Stokes parameters on the magnetic field
applied in the Faraday geometry are measured under continuous wave resonant
excitation of the exciton photoluminescence. Theoretical model is developed to
take into account both bright and dark exciton states in the case of strong
electron and hole exchange interaction and random in-plane orientation of the
nanoplatelets in ensemble. The data analysis allows us to estimate the time and
energy parameters of the bright and dark excitons. The optical alignment effect
enables identification of the exciton and trion contributions to the
photoluminescence spectrum even in the absence of a clear spectral line
resolution.Comment: main paper (17 pages) and SI (6 pages
Pion-Production in Heavy-Ion Collisions at SIS energies
We investigate the production of pions in heavy-ion collisions in the energy
range of - GeV/A. The dynamics of the nucleus-nucleus collisions is
described by a set of coupled transport equations of the
Boltzmann-Uehling-Uhlenbeck type for baryons and mesons. Besides the
and the we also take into account nucleon resonances up to
masses of as well as -, - and -mesons. We study
in detail the influence of the higher baryonic resonances and the
-production channels () on the pion spectra in
comparison to data from collisions at GeV/A and
-data for at 1.0 GeV/A. We, furthermore, present a detailed
comparison of differential pion angular distributions with the BEVALAC data for
Ar + KCl at 1.8 GeV/A. The general agreement obtained indicates that the
overall reactions dynamics is well described by our novel transport approach.Comment: 31 pages, 18 figures (inlcuded), to appear in Z. Phys.
Delta excitation in K^+-nucleus collisions
We present calculations for \Delta excitation in the (K^+,K^+) reaction in
nuclei. The background from quasielastic K^+ scattering in the \Delta region is
also evaluated and shown to be quite small in some kinematical regions, so as
to allow for a clean identification of the \Delta excitation strength. Nuclear
effects tied to the \Delta renormalization in the nucleus are considered and
the reaction is shown to provide new elements to enrich our knowledge of the
\Delta properties in a nuclear medium.Comment: 11 pages, 6 figures, LaTe
Flavor Production in Pb(160AGeV) on Pb Collisions: Effect of Color Ropes and Hadronic Rescattering
Collective interactions in the preequilibrium quark matter and hadronic
resonance gas stage of ultrarelativistic nucleus-nucleus collisions are studied
in the framework of the the transport theoretical approach RQMD. The paper
reviews string fusion into color ropes and hadronic rescattering which serve as
models for these interactions. Hadron production in central Pb(160AGeV) on Pb
collisions has been calculated. The changes of the final flavor composition are
more pronounced than in previous RQMD studies of light ion induced reactions at
200AGeV. The ratio of created quark pairs /(+) is
enhanced by a factor of 2.4 in comparison to results. Color rope formation
increases the initially produced antibaryons to 3 times the value in the `NN
mode', but only one quarter of the produced antibaryons survives because of
subsequent strong absorption. The differences in the final particle composition
for Pb on Pb collisions compared to S induced reactions are attributed to the
hadronic resonance gas stage which is baryon-richer and lasts longer.Comment: 60 pages + 11 postscript figures (uuencoded and included
Theoretical investigation of noncollinear phase-matched parametric four-photon amplification of ultrashort light pulses in isotropic media
Influence of the seeding rate on the formation of anatomical features of the monoecious hemp stems of Diana breed
Some Facts of Main Ethnic Groups’ Ceremonial-Game Traditions in Their Theatrical Aspect in the Chuvash Republic
- …