269 research outputs found
The use of the indentation test for studying the solidification behaviour of different semicrystalline polymers during injection moulding
An in-line method for monitoring the solidification process during injection molding of semicrystalline polymers (demonstrated previously in J. Appl. Polym. Sci.2003, 89, 3713) is based on a simple device, where an additional ejector pin is pushed on the injection molded part at different times during the solidification phase. The ‘indentation depth profile’, i.e., residual deformation as a function of time, was obtained and allowed to determine the evolution of the solidification front in the mold as a function of the cooling time. The present work shows the reliability and the powerfulness of the aforementioned method for a large variety of different semicrystalline polymers (PET, PBT, polyamide-6 PA6, isotactic poly(propylene) iPP) characterized also by different molecular weight and/or nucleating agents. The results show that the indentation test may be considered as a ‘predictive’ tool to qualitatively and quantitatively compare the solidification process of different polymers and polymer grades during injection molding
Electron-radiation interaction in a Penning trap: beyond the dipole approximation
We investigate the physics of a single trapped electron interacting with a
radiation field without the dipole approximation. This gives new physical
insights in the so-called geonium theory.Comment: 12 pages, RevTeX, 6 figures, Approved for publication in Phys. Rev.
Improved Term of the Electron Anomalous Magnetic Moment
We report a new value of electron , or , from 891 Feynman diagrams
of order . The FORTRAN codes of 373 diagrams containing closed
electron loops have been verified by at least two independent formulations. For
the remaining 518 diagrams, which have no closed lepton loop, verification by a
second formulation is not yet attempted because of the enormous amount of
additional work required. However, these integrals have structures that allow
extensive cross-checking as well as detailed comparison with lower-order
diagrams through the renormalization procedure. No algebraic error has been
uncovered for them. The numerical evaluation of the entire term by
the integration routine VEGAS gives , where the
uncertainty is obtained by careful examination of error estimates by VEGAS.
This leads to ,
where the uncertainties come from the term, the estimated
uncertainty of term, and the inverse fine structure constant,
, measured by atom interferometry combined
with a frequency comb technique, respectively. The inverse fine structure
constant derived from the theory and the Seattle
measurement of is .Comment: 64 pages and 10 figures. Eq.(16) is corrected. Comments are added
after Eq.(40
ELENA: An Upgrade to the Antiproton Decelerator
A small decelerator ring with electron cooling is proposed to produce dense antiproton beams at very low energies. The ring should be installed between the existing AD and the experimental area
Solution of the two identical ion Penning trap final state
We have derived a closed form analytic expression for the asymptotic motion
of a pair of identical ions in a high precision Penning trap. The analytic
solution includes the effects of special relativity and the Coulomb interaction
between the ions. The existence and physical relevance of such a final state is
supported by a confluence of theoretical, experimental and numerical evidence.Comment: 5 pages and 2 figure
Antiproton-Hydrogen annihilation at sub-kelvin temperatures
The main properties of the interaction of ultra low-energy antiprotons ( a.u.) with atomic hydrogen are established. They include the
elastic and inelastic cross sections and Protonium (Pn) formation spectrum. The
inverse Auger process () is taken into account in the
framework of an unitary coupled-channels model. The annihilation cross-section
is found to be several times smaller than the predictions made by the black
sphere absorption models. A family of nearthreshold metastable
states is predicited. The dependence of Protonium formation probability on the
position of such nearthreshold S-matrix singularities is analysed. An
estimation for the annihilation cross section is obtained.Comment: latex.tar.gz file, 22 pages, 9 figure
Shot-noise-limited spin measurements in a pulsed molecular beam
Heavy diatomic molecules have been identified as good candidates for use in
electron electric dipole moment (eEDM) searches. Suitable molecular species can
be produced in pulsed beams, but with a total flux and/or temporal evolution
that varies significantly from pulse to pulse. These variations can degrade the
experimental sensitivity to changes in spin precession phase of an electri-
cally polarized state, which is the observable of interest for an eEDM
measurement. We present two methods for measurement of the phase that provide
immunity to beam temporal variations, and make it possible to reach
shot-noise-limited sensitivity. Each method employs rapid projection of the
spin state onto both components of an orthonormal basis. We demonstrate both
methods using the eEDM-sensitive H state of thorium monoxide (ThO), and use one
of them to measure the magnetic moment of this state with increased accuracy
relative to previous determinations.Comment: 12 pages, 6 figure
Quantum Logic with a Single Trapped Electron
We propose the use of a trapped electron to implement quantum logic
operations. The fundamental controlled-NOT gate is shown to be feasible. The
two quantum bits are stored in the internal and external (motional) degrees of
freedom.Comment: 7 Pages, REVTeX, No Figures, To appear in Phys. Rev.
One-Particle Measurement of the Antiproton Magnetic Moment
\DeclareRobustCommand{\pbar}{\HepAntiParticle{p}{}{}\xspace}
\DeclareRobustCommand{\p}{\HepParticle{p}{}{}\xspace}
\DeclareRobustCommand{\mup}{{}{}\xspace}
\DeclareRobustCommand{\mupbar}{\mu_{\pbar}{}{}\xspace}
\DeclareRobustCommand{\muN}{{}{}\xspace
For the first time a single trapped \pbar is used to measure the \pbar
magnetic moment {\bm\mu}_{\pbar}. The moment {\bm\mu}_{\pbar} = \mu_{\pbar}
{\bm S}/(\hbar/2) is given in terms of its spin and the nuclear
magneton (\muN) by \mu_{\pbar}/\mu_N = -2.792\,845 \pm 0.000\,012. The 4.4
parts per million (ppm) uncertainty is 680 times smaller than previously
realized. Comparing to the proton moment measured using the same method and
trap electrodes gives \mu_{\pbar}/\mu_p = -1.000\,000 \pm 0.000\,005 to 5
ppm, for a proton moment ,
consistent with the prediction of the CPT theorem.Comment: 4 pages, 4 figures. arXiv admin note: substantial text overlap with
arXiv:1201.303
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