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A new contribution to the nuclear modification factor of non-photonic electrons in Au+Au collisions at sqrt(s) = 200 GeV
We investigate the effect of the so-called anomalous baryon/meson enhancement
to the nuclear modification factor of non-photonic electrons in Au+Au
collisions at sqrt(s) = 200 GeV. It is demonstrated that an enhancement of the
charm baryon/meson ratio, as it is observed for non-strange and strange
hadrons, can be responsible for part of the amplitude of the nuclear
modification factor of non-photonic electrons. About half of the measured
suppression of non-photonic electrons in the 2-4 pt range can be explained by a
charm baryon/meson enhancement of 5. This contribution to the non-photonic
electron nuclear modification factor has nothing to do with heavy quark energy
loss.Comment: 14 pages, 3 figure
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Optimized Multimode Interference Fiber Based Refractometer in A Reflective Interrogation Scheme
A fiber based refractometer in a reflective interrogation scheme is investigated and optimized. A thin gold film was deposited on the tip of a coreless fiber section, which is spliced with a single mode fiber. The coreless fiber is a multimode waveguide, and the observed effects are due to multimode interference. To investigate and optimize the structure, the multimode part of the sensor is built with 3 different lengths: 58 mm, 29 mm and 17 mm. We use a broadband light source ranging from 1475 nm to 1650 nm and we test the sensors with liquids of varying refractive indices, from 1.333 to 1.438. Our results show that for a fixed wavelength, the sensor sensitivity is independent of the multimode fiber length, but we observed a sensitivity increase of approximately 0.7 nm/RIU for a one-nanometer increase in wavelength
Atomic resolution mapping of phonon excitations in STEM-EELS experiments
Atomically resolved electron energy-loss spectroscopy experiments are
commonplace in modern aberrationcorrected transmission electron microscopes.
Energy resolution has also been increasing steadily with the continuous
improvement of electron monochromators. Electronic excitations however are
known to be delocalised due to the long range interaction of the charged
accelerated electrons with the electrons in a sample. This has made several
scientists question the value of combined high spatial and energy resolution
for mapping interband transitions and possibly phonon excitation in crystals.
In this paper we demonstrate experimentally that atomic resolution information
is indeed available at very low energy losses around 100 meV expressed as a
modulation of the broadening of the zero loss peak. Careful data analysis
allows us to get a glimpse of what are likely phonon excitations with both an
energy loss and gain part. These experiments confirm recent theoretical
predictions on the strong localisation of phonon excitations as opposed to
electronic excitations and show that a combination of atomic resolution and
recent developments in increased energy resolution will offer great benefit for
mapping phonon modes in real space
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