5,009 research outputs found
Triple condensate halo from water droplets impacting on cold surfaces
Understanding the dynamics in the deposition of water droplets onto solid
surfaces is of importance from both fundamental and practical viewpoints. While
the deposition of a water droplet onto a heated surface is extensively studied,
the characteristics of depositing a droplet onto a cold surface and the
phenomena leading to such behavior remain elusive. Here we report the formation
of a triple condensate halo observed during the deposition of a water droplet
onto a cold surface, due to the interplay between droplet impact dynamics and
vapor diffusion. Two subsequent condensation stages occur during the droplet
spreading and cooling processes, engendering this unique condensate halo with
three distinctive bands. We further proposed a scaling model to interpret the
size of each band, and the model is validated by the experiments of droplets
with different impact velocity and varying substrate temperature. Our
experimental and theoretical investigation of the droplet impact dynamics and
the associated condensation unravels the mass and heat transfer among droplet,
vapor and substrate, offer a new sight for designing of heat exchange devices
Shedding light on the pion production in heavy-ion collisions for constraining the high-density symmetry energy
Within the framework of the quantum molecular dynamics transport model, the
pion production and constraint of the high-density symmetry energy in heavy-ion
collisions near threshold energy have been thoroughly investigated. The energy
conservation in the decay of resonances and reabsorption of pions in nuclear
medium are taken into account. The density profile of pion production, energy
conservation and pion potential are analyzed by the model. The isospin
diffusion in the low-density region (0.2 - 0.8) and
high-density region (1.2 - 1.8) is investigated by
analyzing the neutron/proton and ratios in the isotopic
reactions of Sn + Sn and Sn + Sn at the
incident energy of 270 MeV/nucleon, in which the symmetry energy manifests the
opposite contribution. The controversial conclusion of the
ratio for constraining the high-density symmetry energy by different transport
models is clarified. A soft symmetry energy with the slope parameter of
MeV by using the standard error analysis within the
range of is obtained by analyzing the experimental data from the
SRIT collaboration.Comment: 8 pages, 7 figure
Collective flows of clusters and pions in heavy-ion collisions at GeV energies
Within the framework of the quantum molecular dynamics transport model, the
collective flows of clusters and pions in heavy-ion collisions have been
systematically investigated. The clusters are recognized by the Wigner
phase-space density approach at the stage of freeze out in nuclear collisions,
i.e., deuteron, triton, He and . The directed and elliptic flows
of protons and deuterons in the reaction of Au+Au at incident
energy 1.23\emph{A} GeV are nicely consistent with the recent HADES data. The
higher order collective flows, i.e., triangular and quadrangle flows, manifest
the opposite trends with the less amplitude in comparison with the rapidity
distributions of directed and elliptic flows. The flow structure of He
and is very similar to the proton spectra. The influence of the pion
potential on the pion production is systematically investigated and compared
with the FOPI data via the transverse momentum, longitudinal rapidity and
collective flows in collisions of Au + Au. It is manifested
that the pion yields are slightly suppressed in the domain of mid-rapidity and
high momentum. The antiflow phenomena is reduced by implementing the pion
potential and more consistent with the FOPI data in collisions of
Au+Au at the incident energy 1.5\emph{A} GeV.Comment: 11 pages, 9 figures. arXiv admin note: substantial text overlap with
arXiv:2302.0213
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