The paper presents recent PHENIX results on hadron production in heavy ion collisions. Comparison of light hadron (
,
,
,
,
,
,
,
,
) nuclear modification factors in Au
Au, Cu
Au collisions at
GeV ...and U
U collisions at
GeV will be discussed.
Controlled formation of metastable phases is one of the challenges of the physics of crystal growth. Gold-catalyzed nanowires are considered to be one of the most convenient systems to study this ...phenomenon. Studies of antimonide-based nanowires indicate that they preferentially crystallize in the zinc blende crystal structure rather than wurtzite, which is common in other III-V nanowire materials. Here we propose a new approach to the formation of antimonide nanowire segments in the metastable wurtzite phase and support it with theoretical results. The hexagonal crystal phase is stabilized due to the elastic strain. We suggest that this approach can be applied to other III-V nanowires as well.
The paper presents the results on
,
and
production in small collision systems at
GeV as a function of transverse momentum at midrapidity (
) measured by the PHENIX experiment.
Catalyst-free growth of III-V nanowires enables different optoelectronic applications though usually requires substrate patterning to control the size and position of nanowires. However, the impact ...of substrate modification on the nanowire nucleation is not well-understood yet. The theoretical approach of this work studies the effect of substrate boundaries and adatom diffusion on the nucleation rate of catalyst-free III-V NWs on substrates with circularly symmetric patterning. In the model results, we distinguish and demonstrate four different scenarios of nanowire nucleation, depending on the properties of the patterned and unpatterned surfaces.
We present experimental data on the length distributions of InAs nanowires grown by chemical beam epitaxy with Au catalyst nanoparticles obtained by thermal dewetting of Au film, Au colloidal ...nanoparticles and In droplets. Poissonian length distributions are observed in the first case. Au colloidal nanoparticles produce broader and asymmetric length distributions of InAs nanowires. However, the distributions can be strongly narrowed by removing the high temperature annealing step. The length distributions for the In-catalyzed growth are instead very broad. We develop a generic model that is capable of describing the observed behaviors by accounting for both the incubation time for nanowire growth and secondary nucleation of In droplets. These results allow us to formulate some general recipes for obtaining more uniform length distributions of III-V nanowires.
Nuclear modification factor
R
AA
of π
0
mesons produced in
3
HeAu collisions at a cms energy of
= 200 GeV is extracted from data of the PHENIX experiment at the RHIC. The mean
R
AA
value for π
0
... mesons with
p
T
> 8 GeV/
c
is found to be close to 0.8 for central
3
He + Au collisions.
Results are presented from measuring nuclear modification factors
R
AA
of the π
0
, η,
K
S
, and ω mesons produced in systems of Cu + Au and U + U collisions at cms energies of
= 200 and 192 GeV, ...respectively, in the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC). The
R
AA
values are found not to depend on the type of neutral meson and to vary in the ~0.4–0.6 and ~0.2–0.3 intervals for central Cu + Au and U + U collisions, respectively. The mean
R
AA
values for different collision systems (Au + Au, Cu + Cu, Cu + Au, and U + U) are found to coincide within the measuring errors when estimated at comparable values of collision energy
, and of the number of nucleons participating in a nucleus–nucleus collision,
N
part
.
We present a non-stationary growth model of Ga-catalyzed GaAs nanowires which is based on the two kinetic equations for the nanowire elongation rate and a time-dependent base radius of the droplet. ...We show that self-catalyzed nanowire growth is principally different from the Au-catalyzed one because a stationary droplet size cannot be maintained at all times. Close examination of the model enables us to separate different regimes of radial growth in which the droplet shrinks, inflates or converges to a certain stationary size as nanowires grow, depending on the initial droplet radius and the growth conditions. We also discuss some experimental data on the growth modes of Ga-catalyzed GaAs nanowires from the viewpoint of the obtained results.
—A model of spontaneous formation of the core-shell structure in (In,Ga)As nanowire grown via molecular beam epitaxy without independent radial growth is proposed. Within the framework of the ...proposed model, the distribution of In across the axis of the nanowire was fitted.
The growth of ternary nanowires via the vapor-liquid-solid mechanism is one of the possible ways of band gap engineering. However, the dependence of ternary nanowire composition on growth parameters ...is still unclear. We compare two theoretical approaches to ternary nanowire composition determined either by the formation of the critical island or by the step-flow growth of the monolayer. For typical parameters of gold-catalyzed growth, these two models give similar results. In the case of self-catalyzed growth, the step-determined model predicts higher In content in the NW than the island-determined.
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