6,663 research outputs found
The Dependence of Work Function on Thickness in Epitaxial Cu-Pd Systems
Changes in work function have been measured with a Kelvin probe for the initial stages of epitaxial growth of (111) Cu on (111) Pd and (111) Pd on (111) Cu and for CO adsorption on selected bilayers at room temperature. The results of this study show that, at low metal coverages, the overlayers have properties which differ significantly from those of bulk crystals. One of the most interesting observations was that a quarter monolayer of Cu on Pd (111) increases the saturation work function change upon CO adsorption by more than a factor of three as compared to a thick Pd (111) film
Invariance: a Theoretical Approach for Coding Sets of Words Modulo Literal (Anti)Morphisms
Let be a finite or countable alphabet and let be literal
(anti)morphism onto (by definition, such a correspondence is determinated
by a permutation of the alphabet). This paper deals with sets which are
invariant under (-invariant for short).We establish an
extension of the famous defect theorem. Moreover, we prove that for the
so-called thin -invariant codes, maximality and completeness are two
equivalent notions. We prove that a similar property holds in the framework of
some special families of -invariant codes such as prefix (bifix) codes,
codes with a finite deciphering delay, uniformly synchronized codes and
circular codes. For a special class of involutive antimorphisms, we prove that
any regular -invariant code may be embedded into a complete one.Comment: To appear in Acts of WORDS 201
Radon mitigation during the installation of the CUORE decay detector
CUORE - the Cryogenic Underground Observatory for Rare Events - is an
experiment searching for the neutrinoless double-beta () decay
of Te with an array of 988 TeO crystals operated as bolometers at
10 mK in a large dilution refrigerator. With this detector, we aim for a
Te decay half-life sensitivity of y
with 5 y of live time, and a background index of
counts/keV/kg/y. Making an effort to maintain radiopurity by minimizing the
bolometers' exposure to radon gas during their installation in the cryostat, we
perform all operations inside a dedicated cleanroom environment with a
controlled radon-reduced atmosphere. In this paper, we discuss the design and
performance of the CUORE Radon Abatement System and cleanroom, as well as a
system to monitor the radon level in real time.Comment: 10 pages, 6 figures, 1 tabl
Évaluation de la fonction des membres présentant un lymphœdème par un nouveau test après rééducation intensive
Detection of the Natural Alpha Decay of Tungsten
The natural alpha decay of 180W has been unambiguously detected for the first
time. The alpha peak is found in a (gamma,beta and neutron)-free background
spectrum. This has been achieved by the simultaneous measurement of phonon and
light signals with the CRESST cryogenic detectors. A half-life of T1/2 = (1.8
+- 0.2) x 10^18 y and an energy release of Q = (2516.4 +- 1.1 (stat.) +- 1.2
(sys.)) keV have been measured. New limits are also set on the half-lives of
the other naturally occurring tungsten isotopes.Comment: Submitted to Physical Review C Revised versio
A variational approach to strongly damped wave equations
We discuss a Hilbert space method that allows to prove analytical
well-posedness of a class of linear strongly damped wave equations. The main
technical tool is a perturbation lemma for sesquilinear forms, which seems to
be new. In most common linear cases we can furthermore apply a recent result
due to Crouzeix--Haase, thus extending several known results and obtaining
optimal analyticity angle.Comment: This is an extended version of an article appeared in
\emph{Functional Analysis and Evolution Equations -- The G\"unter Lumer
Volume}, edited by H. Amann et al., Birkh\"auser, Basel, 2008. In the latest
submission to arXiv only some typos have been fixe
The CRESST Dark Matter Search
We present first competitive results on WIMP dark matter using the
phonon-light-detection technique. A particularly strong limit for WIMPs with
coherent scattering results from selecting a region of the phonon-light plane
corresponding to tungsten recoils. The observed count rate in the neutron band
is compatible with the rate expected from neutron background. CRESST is
presently being upgraded with a 66 channel SQUID readout system, a neutron
shield and a muon veto system. This results in a significant improvement in
sensitivity.Comment: 6 pages, 3 figures, to be published in the proceedings of the 5th
International Workshop on the Identification and Detection of Dark Matter IDM
2004, Edinburgh, Sept. 2004, World Scientifi
Limits on Dark Matter Effective Field Theory Parameters with CRESST-II
CRESST is a direct dark matter search experiment, aiming for an observation
of nuclear recoils induced by the interaction of dark matter particles with
cryogenic scintillating calcium tungstate crystals. Instead of confining
ourselves to standard spin-independent and spin-dependent searches, we
re-analyze data from CRESST-II using a more general effective field theory
(EFT) framework. On many of the EFT coupling constants, improved exclusion
limits in the low-mass region (< 3-4 GeV) are presented.Comment: 7 pages, 9 figure
The incommensurate charge-density-wave instability in the extended three-band Hubbard model
The infinite-U three-band Hubbard model is considered in order to describe
the CuO_2 planes of the high temperature superconducting cuprates. The charge
instabilities are investigated when the model is extended with a
nearest-neighbor repulsion between holes on copper d and oxygen p orbitals and
in the presence of a long-range Coulombic repulsion. It is found that a
first-order valence instability line ending with a critical point is present
like in the previously investigated model without long-range forces. However,
the dominant critical instability is the formation of incommensurate
charge-density-waves, which always occur before the valence-instability
critical point is reached. An effective singular attraction arises in the
proximity of the charge-density wave instability, accounting for both a strong
pairing mechanism and for the anomalous normal state properties.Comment: 15 pages in RevteX. Figures available from M. Grill
The CRESST Dark Matter Search
The current status of CRESST (Cryogenic Rare Event Search using
Superconducting Thermometers) and new results concerning the detector
development are presented. The basic technique of CRESST is to search for
particle Dark Matter (WIMPS, Weakly Interacting Massive particles) by the
measurement of non-thermal phonons as created by WIMP-induced nuclear recoils.
Combined with the newly developed method of simultaneous measurement of
scintillation light, strong background discrimination is possible, resulting in
a substantial increase in WIMP detection sensitivity. The short and long term
perspectives of CRESST are discussed.Comment: 12 pages, 6 figure
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