339 research outputs found
BRAHMS Overview
A brief review of BRAHMS measurements of bulk particle production in RHIC
Au+Au collisions at is presented, together with some
discussion of baryon number transport. Intermediate measurements in
different collision systems (Au+Au, d+Au and p+p) are also discussed in the
context of jet quenching and saturation of the gluon density in Au ions at RHIC
energies. This report also includes preliminary results for identified
particles at forward rapidities in d+Au and Au+Au collisions.Comment: 8 pages 6 figures, Invited plenary talk at 5th International
Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPAQGP 2005),
Salt Lake City, Kolkata, India, 8-12 Feb 200
Formation of van der Waals molecules in buffer gas cooled magnetic traps
We show that a large class of helium-containing cold polar molecules form
readily in a cryogenic buffer gas, achieving densities as high as 10^12 cm^-3.
We explore the spin relaxation of these molecules in buffer gas loaded magnetic
traps, and identify a loss mechanism based on Landau-Zener transitions arising
from the anisotropic hyperfine interaction. Our results show that the recently
observed strong T^6 thermal dependence of spin change in buffer gas trapped
silver (Ag) is accounted for by the formation and spin change of AgHe, thus
providing evidence for molecular formation in a buffer gas trap.Comment: 4 pages, 4 figure
Quark coalescence in the mid rapidity region at RHIC
We utilize the ALCOR model for mid-rapidity hadron number predictions at AGS,
SPS and RHIC energies. We present simple fits for the energy dependence of
stopping and quark production.Comment: Talk given at SQM2001, Frankfurt, (LaTeX 8 pages, 5 .ps figs
Cronin Effect at Different Rapidities at RHIC
Calculations of the nuclear modification factor, R_dAu, for pi^0 production
in dAu collisions at s_NN^1/2 = 200 GeV are presented. The applied
pQCD-improved parton model incorporates intrinsic k_T. Nuclear multiscattering
and nuclear shadowing are considered in the Au nucleus. Theoretical results are
displayed for midrapidity and high pseudorapidity (eta), and compared to
preliminary PHENIX and BRAHMS data.Comment: Contributed to 17th International Conference on Ultra Relativistic
Nucleus-Nucleus Collisions (Quark Matter 2004), Oakland, California, 11-17
Jan 200
CGC, QCD Saturation and RHIC data (Kharzeev-Levin-McLerran-Nardi point of view)
This is the talk given at the Workshop:"Focus on Multiplicitioes", Bari,
Italy, 17-19 June,2004.. In this talk, we are going to discuss ion-ion and
deuteron - nucleus RHIC data and show that they support, if not more, the idea
of the new QCD phase: colour glass condensate with saturated parton density. .Comment: 26 pages with 33 figure
Direct characterisation of tuneable few-femtosecond dispersive-wave pulses in the deep UV
Dispersive wave emission (DWE) in gas-filled hollow-core dielectric
waveguides is a promising source of tuneable coherent and broadband radiation,
but so far the generation of few-femtosecond pulses using this technique has
not been demonstrated. Using in-vacuum frequency-resolved optical gating, we
directly characterise tuneable 3fs pulses in the deep ultraviolet generated via
DWE. Through numerical simulations, we identify that the use of a pressure
gradient in the waveguide is critical for the generation of short pulses.Comment: 5 pages, 4 figure
Buffer gas cooling and trapping of atoms with small magnetic moments
Buffer gas cooling was extended to trap atoms with small magnetic moment
(mu). For mu greater than or equal to 3mu_B, 1e12 atoms were buffer gas cooled,
trapped, and thermally isolated in ultra high vacuum with roughly unit
efficiency. For mu < 3mu_B, the fraction of atoms remaining after full thermal
isolation was limited by two processes: wind from the rapid removal of the
buffer gas and desorbing helium films. In our current apparatus we trap atoms
with mu greater than or equal to 1.1mu_B, and thermally isolate atoms with mu
greater than or equal to 2mu_B. Extrapolation of our results combined with
simulations of the loss processes indicate that it is possible to trap and
evaporatively cool mu = 1mu_B atoms using buffer gas cooling.Comment: 17 pages, 4 figure
Cognitive-postural multitasking training in older adults: Effects of input-output modality mappings on cognitive performance and postural control
Older adults exhibit impaired cognitive and balance performance, particularly under multi-task conditions, which can be improved through training. Compatibility of modality mappings in cognitive tasks (i.e., match between stimulus modality and anticipated sensory effects of motor responses), modulates physical and cognitive dual-task costs. However, the effects of modality specific training programs have not been evaluated yet. Here, we tested the effects of cognitive-postural multi-tasking training on the ability to coordinate task mappings under high postural demands in healthy older adults. Twenty-one adults aged 65-85 years were assigned to one of two groups. While group 1 performed cognitive-postural triple-task training with compatible modality mappings (i.e., visual-manual and auditory-vocal dual n-back tasks), group 2 performed the same tasks with incompatible modality mappings (i.e., visual-vocal and auditory-manual n-back tasks). Throughout the 6-weeks balance training intervention, working-memory load was gradually increased while base-of-support was reduced. Before training (T0), after a 6-week passive control period (T1), and immediately after the intervention (T2), participants performed spatial dual one-back tasks in semi-tandem stance position. Our results indicate improved working-memory performance and reduced dual-task costs for both groups after the passive control period, but no training-specific performance gains. Furthermore, balance performance did not improve in response to training. Notably, the cohort demonstrated meaningful interindividual variability in training responses. Our findings raise questions about practice effects and age-related heterogeneity of training responses following cognitive-motor training. Following multi-modal balance training, neither compatible nor incompatible modality mappings had an impact on the observed outcomes
Is Strangeness still interesting at RHIC ?
With the advent of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven
National Laboratory (BNL), Heavy Ion Physics will enter a new energy regime.
The question is whether the signatures proposed for the discovery of a phase
transition from hadronic matter to a Quark Gluon Plasma (QGP), that were
established on the basis of collisions at the BEVALAC, the AGS, and the SPS,
respectively, are still useful and detectable at these high incident energies.
In the past two decades, measurements related to strangeness formation in the
collision were advocated as potential signatures and were tested in numerous
fixed target experiments at the AGS and the SPS. In this article I will review
the capabilities of the RHIC detectors to measure various aspects of
strangeness, and I will try to answer the question whether the information
content of those measurements is comparable to the one at lower energies.Comment: 12 pages, 7 figures, Invited Talk at the IV International Conference
on Strangeness in Quark Matter, Padova (Italy), July 20-24, 199
Rapidity dependence of hadron production in central Au+Au collisions at GeV
The rapidity and transverse momentum spectra for identified hadrons in
central Au+Au collisions at GeV are computed in a quark
combination model. The data of rapidity distributions for ,
, and net protons are well described. We
also predict rapidity distributions for , ,
() and
. The multiplicity ratios of
charged antihadrons to hadrons as a function of rapidity are reproduced. The
results for spectra of , , and for
the ratios in a broader range agree well with the data.
Finally the rapidity dependence of transverse momentum distributions for
hadrons are given.Comment: 10 pages,11figures,3 table
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