5,108 research outputs found
Nuclear modification at sqrt{s_{NN}}=17.3 GeV, measured at NA49
Transverse momentum spectra up to 4.5 GeV/c were measured around midrapidity
in Pb+Pb reactions at sqrt{s_{NN}}=17.3 GeV, for pi^{+/-}, p, pbar and K^{+/-},
by the NA49 experiment. The nuclear modification factors R_{AA}, R_{AA/pA} and
R_{CP} were extracted and are compared to RHIC results at sqrt{s_{NN}}=200 GeV.
The modification factor R_{AA} shows a rapid increase with transverse momentum
in the covered region. The modification factor R_{CP} shows saturation well
below unity in the pi^{+/-} channel. The extracted R_{CP} values follow the 200
GeV RHIC results closely in the available transverse momentum range for all
particle species. For pi^{+/-} above 2.5 GeV/c transverse momentum, the
measured suppression is smaller than that observed at RHIC. The nuclear
modification factor R_{AA/pA} for pi^{+/-} stays well below unity.Comment: Proceedings of Quark Matter 2008 conferenc
Trapped Ion Imaging with a High Numerical Aperture Spherical Mirror
Efficient collection and analysis of trapped ion qubit fluorescence is
essential for robust qubit state detection in trapped ion quantum computing
schemes. We discuss simple techniques of improving photon collection efficiency
using high numerical aperture (N.A.) reflective optics. To test these
techniques we placed a spherical mirror with an effective N.A. of about 0.9
inside a vacuum chamber in the vicinity of a linear Paul trap. We demonstrate
stable and reliable trapping of single barium ions, in excellent agreement with
our simulations of the electric field in this setup. While a large N.A.
spherical mirror introduces significant spherical aberration, the ion image
quality can be greatly improved by a specially designed aspheric corrector lens
located outside the vacuum system. Our simulations show that the spherical
mirror/corrector design is an easy and cost-effective way to achieve high
photon collection rates when compared to a more sophisticated parabolic mirror
setup.Comment: 5 figure
Status and plans of the ion program of NA61 at the CERN SPS
The NA61/SHINE at the CERN SPS is a new experiment to study hadron production
in p+p p+A, h+A and A+A interactions. The main goal of the NA61 ion program is
to explore the phase diagram (T - mu_B) of strongly interacting matter. In
particular, we plan to study the properties of the onset of deconfinement and
to search for the signatures of the critical point. A two-dimensional scan of
the phase diagram will be performed by varying the energy (13A-158A GeV) and
system size (p+p, Be+Be, Ar+Ca, Xe+La) of collisions. This paper summarizes the
status and plans of the NA61/SHINE ion program. In particular the detector
upgrades, data taking schedule and the first results on spectra and
correlations are discussed.Comment: Proceedings of "Critical Point and Onset of Deconfinement - CPOD
2011", Wuhan, November 7-11, 2011, version accepted by Central European
Journal of Physic
Geometric approach to nonvariational singular elliptic equations
In this work we develop a systematic geometric approach to study fully
nonlinear elliptic equations with singular absorption terms as well as their
related free boundary problems. The magnitude of the singularity is measured by
a negative parameter , for , which reflects on
lack of smoothness for an existing solution along the singular interface
between its positive and zero phases. We establish existence as well sharp
regularity properties of solutions. We further prove that minimal solutions are
non-degenerate and obtain fine geometric-measure properties of the free
boundary . In particular we show sharp
Hausdorff estimates which imply local finiteness of the perimeter of the region
and a.e. weak differentiability property of
.Comment: Paper from D. Araujo's Ph.D. thesis, distinguished at the 2013 Carlos
Gutierrez prize for best thesis, Archive for Rational Mechanics and Analysis
201
Correlations due to localization in quantum eigenfunctions of disordered microwave cavities
Non-universal correlations due to localization are observed in statistical
properties of experimental eigenfunctions of quantum chaotic and disordered
microwave cavities. Varying energy {E} and mean free path {l} enable us to
experimentally tune from localized to delocalized states. Large level-to-level
Inverse Participation Ratio (IPR I_{2}) fluctuations are observed for the
disordered billiards, whose distribution is strongly asymmetric about .
The density auto-correlations of eigenfunctions are shown to decay
exponentially and the decay lengths are experimentally determined. All the
results are quantitatively consistent with calculations based upon nonlinear
sigma-models.Comment: 4 pages, LaTex, 5 .jpg figures. This paper with 5 embedded postscript
figures available (PS,PDF) at http://sagar.physics.neu.edu/preprints
Evidence of the Coulomb force effects in the cross sections of the deuteron-proton breakup at 130 MeV
High precision cross-section data of the deuteron-proton breakup reaction at
130 MeV deuteron energy are compared with the theoretical predictions obtained
with a coupled-channel extension of the CD Bonn potential with virtual
Delta-isobar excitation, without and with inclusion of the long-range Coulomb
force. The Coulomb effect is studied on the basis of the cross-section data
set, extended in this work to about 1500 data points by including breakup
geometries characterized by small polar angles of the two protons. The
experimental data clearly prefer predictions obtained with the Coulomb
interaction included. The strongest effects are observed in regions in which
the relative energy of the two protons is the smallest.Comment: 9 pages, 3 figures, submitted to Physics Letters
Tangential Touch between the Free and the Fixed Boundary in a Semilinear Free Boundary Problem in Two Dimensions
The main result of this paper concerns the behavior of a free boundary
arising from a minimization problem, close to the fixed boundary in two
dimensions
Trojan Horse as an indirect technique in nuclear astrophysics. Resonance reactions
The Trojan Horse method is a powerful indirect technique that provides
information to determine astrophysical factors for binary rearrangement
processes at astrophysically relevant energies by measuring
the cross section for the Trojan Horse reaction in
quasi-free kinematics. We present the theory of the Trojan Horse method for
resonant binary subreactions based on the half-off-energy-shell R matrix
approach which takes into account the off-energy-shell effects and initial and
final state interactions.Comment: 6 pages and 1 figur
Analyzing symmetry breaking within a chaotic quantum system via Bayesian inference
Bayesian inference is applied to the level fluctuations of two coupled
microwave billiards in order to extract the coupling strength. The coupled
resonators provide a model of a chaotic quantum system containing two coupled
symmetry classes of levels. The number variance is used to quantify the level
fluctuations as a function of the coupling and to construct the conditional
probability distribution of the data. The prior distribution of the coupling
parameter is obtained from an invariance argument on the entropy of the
posterior distribution.Comment: Example from chaotic dynamics. 8 pages, 7 figures. Submitted to PR
The Balian-Br\'ezin Method in Relativistic Quantum Mechanics
The method suggested by Balian and Br\'ezin for treating angular momentum
reduction in the Faddeev equations is shown to be applicable to the
relativistic three-body problem.Comment: 14 pages in LaTe
- …