11,165 research outputs found
Dimensional enhancement of kinetic energies
Simple thermodynamics considers kinetic energy to be an extensive variable
which is proportional to the number, N, of particles. We present a quantum
state of N non-interacting particles for which the kinetic energy increases
quadratically with N. This enhancement effect is tied to the quantum
centrifugal potential whose strength is quadratic in the number of dimensions
of configuration space.Comment: 9 pages, accepted by Phys. Rev.
On the concepts of radial and angular kinetic energies
We consider a general central-field system in D dimensions and show that the
division of the kinetic energy into radial and angular parts proceeds
differently in the wavefunction picture and the Weyl-Wigner phase-space
picture. Thus, the radial and angular kinetic energies are different quantities
in the two pictures, containing different physical information, but the
relation between them is well defined. We discuss this relation and illustrate
its nature by examples referring to a free particle and to a ground-state
hydrogen atom.Comment: 10 pages, 2 figures, accepted by Phys. Rev.
Extreme points of the set of density matrices with positive partial transpose
We present a necessary and sufficient condition for a finite dimensional
density matrix to be an extreme point of the convex set of density matrices
with positive partial transpose with respect to a subsystem. We also give an
algorithm for finding such extreme points and illustrate this by some examples.Comment: 4 pages, 2 figure
Nonflammable, antistatic, and heat-sealable film
Antistatic, heat-sealable, nonflammable films prepared from polyvinylidene fluoride and polyvinylidene chloride resin
Hydrogen atom in phase space. The Kirkwood-Rihaczek representation
We present a phase-space representation of the hydrogen atom using the
Kirkwood-Rikaczek distribution function. This distribution allows us to obtain
analytical results, which is quite unique because an exact analytical form of
the Wigner functions corresponding to the atom states is not known. We show how
the Kirkwood-Rihaczek distribution reflects properties of the hydrogen atom
wave functions in position and momentum representations.Comment: 5 pages (and 5 figures
Nuclear recoil energy scale in liquid xenon with application to the direct detection of dark matter
We show for the first time that the quenching of electronic excitation from
nuclear recoils in liquid xenon is well-described by Lindhard theory, if the
nuclear recoil energy is reconstructed using the combined (scintillation and
ionization) energy scale proposed by Shutt {\it et al.}. We argue for the
adoption of this perspective in favor of the existing preference for
reconstructing nuclear recoil energy solely from primary scintillation. We show
that signal partitioning into scintillation and ionization is well-described by
the Thomas-Imel box model. We discuss the implications for liquid xenon
detectors aimed at the direct detection of dark matter
Performance and Fundamental Processes at Low Energy in a Two-Phase Liquid Xenon Dark Matter Detector
We extend the study of the performance of a prototype two-phase liquid xenon
WIMP dark matter detector to recoil energies below 20 keV. We demonstrate a new
method for obtaining the best estimate of the energies of events using a
calibrated sum of charge and light signals and introduce the corresponding
discrimination parameter, giving its mean value at 4 kV/cm for electron and
nuclear recoils up to 300 and 100 keV, respectively. We show that fluctuations
in recombination limit discrimination for most energies, and reveal an
improvement in discrimination below 20 keV due to a surprising increase in
ionization yield for low energy electron recoils. This improvement is crucial
for a high-sensitivity dark matter search.Comment: 4 pages, 6 figures, submitted to DM06 conference proceedings in Nucl
Phys
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