827 research outputs found
Corrosion-protective coatings from electrically conducting polymers
In a joint effort between NASA Kennedy and LANL, electrically conductive polymer coatings were developed as corrosion protective coatings for metal surfaces. At NASA Kennedy, the launch environment consist of marine, severe solar, and intermittent high acid and/or elevated temperature conditions. Electrically conductive polymer coatings were developed which impart corrosion resistance to mild steel when exposed to saline and acidic environments. Such coatings also seem to promote corrosion resistance in areas of mild steel where scratches exist in the protective coating. Such coatings appear promising for many commercial applications
Detection of motional ground state population of a trapped ion using delayed pulses
Efficient preparation and detection of the motional state of trapped ions is
important in many experiments ranging from quantum computation to precision
spectroscopy. We investigate the stimulated Raman adiabatic passage (STIRAP)
technique for the manipulation of motional states in a trapped ion system. The
presented technique uses a Raman coupling between two hyperfine ground states
in Mg, implemented with delayed pulses, which removes a single
phonon independent of the initial motional state. We show that for a thermal
state the STIRAP population transfer is more efficient than a stimulated Raman
Rabi pulse on a motional sideband. In contrast to previous implementations, a
large detuning of more than 200 times the natural linewidth of the transition
is used. This approach renders STIRAP suitable for atoms in which resonant
laser fields would populate fluorescing excited states and thus impede the
STIRAP process. We use the technique to measure the wavefunction overlap of
excited motional states with the motional ground state. This is an important
application for photon recoil spectroscopy and other force sensing applications
that utilize the high sensitivity of the motional state of trapped ions to
external fields. Furthermore, a determination of the ground state population
enables a simple measurement of the ion's temperature.Comment: 17 pages, 7 figure
Vitamin E content of different animal products: Influence of animal nutrition
Zusammenfassung: In der vorliegenden Studie wurde der α-Tocopherolgehalt verschiedener Fleischstücke untersucht. Hähnchenschenkel hatte den höchsten α-Tocopherolgehalt, gefolgt von Hähnchenbrust und Schweineschulter (p Leber > Fettgewebe >Musculus longissimus dorsi. Die Nährstoffdichten betrugen 28.8, 7.3, 0.9 und 1.2 mg α-Tocopherol/MJ für Eigelb, Leber, Fettgewebe und Musculus longissimus dorsi der jeweiligen mit Vitamin E supplementierten Gruppe. Diese Ergebnisse zeigen, daß Fleisch, mit Ausnahme des Hähnchenschenkels, von Tieren mit supplementierten Diäten kein bedeutender Vitamin E-Lieferant ist. Hingegen wurde Eigelb durch fütterungsbedingte Modifikation zu einer guten Vitamin E-Quell
Precision isotope shift measurements in Ca using highly sensitive detection schemes
We demonstrate an efficient high-precision optical spectroscopy technique for
single trapped ions with non-closed transitions. In a double-shelving
technique, the absorption of a single photon is first amplified to several
phonons of a normal motional mode shared with a co-trapped cooling ion of a
different species, before being further amplified to thousands of fluorescence
photons emitted by the cooling ion using the standard electron shelving
technique. We employ this extension of the photon recoil spectroscopy technique
to perform the first high precision absolute frequency measurement of the
D P transition in Ca,
resulting in a transition frequency of kHz.
Furthermore, we determine the isotope shift of this transition and the
S P transition for Ca,
Ca and Ca ions relative to Ca with an
accuracy below 100 kHz. Improved field and mass shift constants of these
transitions as well as changes in mean square nuclear charge radii are
extracted from this high resolution data
QCD spectroscopy with three light quarks
We report about a simulation using three dynamical Wilson quarks and on the
progress in going to small quark masses.Comment: Lattice2001(spectrum), 3 pages, 4 figure
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