359 research outputs found
Probing weak force induced parity violation by high resolution mid-infrared molecular spectroscopy
To date no experiment has reached the level of sensitivity required to
observe weak nuclear force induced parity violation (PV) energy differences in
chiral molecules. In this paper, we present the approach, adopted at
Laboratoire de Physique des Lasers (LPL), to measure frequency differences in
the vibrational spectrum of enantiomers. We review different spectroscopic
methods developed at LPL leading to the highest resolutions, as well as 20
years of CO2 laser stabilization work enabling such precise measurements. After
a first attempt to observe PV vibrational frequency shifts using sub-Doppler
saturated absorption spectroscopy in a cell, we are currently aiming at an
experiment based on Doppler-free two-photon Ramsey interferometry on a
supersonic beam. We report on our latest progress towards observing PV with
chiral organo-metallic complexes containing a heavy rhenium atom
Mid-IR frequency measurement using an optical frequency comb and a long-distance remote frequency reference
We have built a frequency chain which enables to measure the absolute
frequency of a laser emitting in the 28-31 THz frequency range and stabilized
onto a molecular absorption line. The set-up uses an optical frequency comb and
an ultrastable 1.55 m frequency reference signal, transferred from
LNE-SYRTE to LPL through an optical link. We are now progressing towards the
stabilization of the mid-IR laser via the frequency comb and the extension of
this technique to quantum cascade lasers. Such a development is very
challenging for ultrahigh resolution molecular spectroscopy and fundamental
tests of physics with molecules
Traité de paysage mis a la portée de Tous
Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201
Traité méthodique et raisonné de la peinture a l`¿huile, contanant les principes du coloris ou mélanges dew couleurs appliqués a tous les genres ...; suivi de L¿art de la restauration et conservation des tableaux / par Goupil et Desloges
Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201
Visual Patterns Discovery in Large Databases of Paintings
The digitization of large databases of works of arts photographs opens new avenue for research in art history. For instance, collecting and analyzing painting representations beyond the relatively small number of commonly accessible works was previously extremely challenging. In the coming years,researchers are likely to have an easier access not only to representations of paintings from museums archives but also from private collections, fine arts auction houses, art historian However, the access to large online database is in itself not sufficient. There is a need for efficient search engines, capable of searching painting representations not only on the basis of textual metadata but also directly through visual queries. In this paper we explore how convolutional neural network descriptors can be used in combination with algebraic queries to express powerful search queries in the context of art history research
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TAO Conceptual Design Report: A Precision Measurement of the Reactor Antineutrino Spectrum with Sub-percent Energy Resolution
The Taishan Antineutrino Observatory (TAO, also known as JUNO-TAO) is a
satellite experiment of the Jiangmen Underground Neutrino Observatory (JUNO). A
ton-level liquid scintillator detector will be placed at about 30 m from a core
of the Taishan Nuclear Power Plant. The reactor antineutrino spectrum will be
measured with sub-percent energy resolution, to provide a reference spectrum
for future reactor neutrino experiments, and to provide a benchmark measurement
to test nuclear databases. A spherical acrylic vessel containing 2.8 ton
gadolinium-doped liquid scintillator will be viewed by 10 m^2 Silicon
Photomultipliers (SiPMs) of >50% photon detection efficiency with almost full
coverage. The photoelectron yield is about 4500 per MeV, an order higher than
any existing large-scale liquid scintillator detectors. The detector operates
at -50 degree C to lower the dark noise of SiPMs to an acceptable level. The
detector will measure about 2000 reactor antineutrinos per day, and is designed
to be well shielded from cosmogenic backgrounds and ambient radioactivities to
have about 10% background-to-signal ratio. The experiment is expected to start
operation in 2022
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