4,400 research outputs found
New critical behavior in unconventional ferromagnetic superconductors
New critical behavior in unconventional superconductors and superfluids is
established and described by the Wilson-Fisher renormalization-group method.
For certain ordering symmetries a new type of fluctuation-driven first order
phase transitions at finite and zero temperature are predicted. The results can
be applied to a wide class of ferromagnetic superconducting and superfluid
systems, in particular, to itinerant ferromagnets as UGe2 and URhGe.Comment: 12 pages, 6 fig
Meissner phases in spin-triplet ferromagnetic superconductors
We present new results for the properties of phases and phase transitions in
spin-triplet ferromagnetic superconductors. The superconductivity of the mixed
phase of coexistence of ferromagnetism and unconventional superconductivity is
triggered by the presence of spontaneous magnetization. The mixed phase is
stable but the other superconducting phases that usually exist in
unconventional superconductors are either unstable or for particular values of
the parameters of the theory some of them are metastable at relatively low
temperatures in a quite narrow domain of the phase diagram. Phase transitions
from the normal phase to the phase of coexistence is of first order while the
phase transition from the ferromagnetic phase to the coexistence phase can be
either of first or second order depending on the concrete substance. Cooper
pair and crystal anisotropies determine a more precise outline of the phase
diagram shape and reduce the degeneration of ground states of the system but
they do not change drastically phase stability domains and thermodynamic
properties of the respective phases. The results are discussed in view of
application to metallic ferromagnets as UGe2, ZrZn2, URhGe.Comment: 21 pages, 7 figures; Phys. Rev. B (2005) in pres
New features of the phase transition to superconducting state in thin films
The Halperin-Lubensky-Ma (HLM) effect of a fluctuation-induced change of the
order of phase transition in thin films of type I superconductors with
relatively small Ginzburg-Landau number is considered. Numerical data
for the free energy, the order parameter jump, the latent heat, and the
specific heat of W, Al and In are presented to reveal the influence of film
thickness and material parameters on the properties of the phase transition. We
demonstrate for the first time that in contrast to the usual notion the HLM
effect occurs in the most distinct way in superconducting films with high
critical magnetic field rather than in materials with small .
The possibility for an experimental observation of the fluctuation change of
the order of superconducting phase transition in superconducting films is
discussed.Comment: 11 pages, MikTexTeX, 3 fig, 2 Tables, corrected some typos, Submitted
J.Phys:Cond Ma
Tourism satellite accounts – an information basis for the analysis of tourism expenditure
In order to develop management decisions promoting sustainable tourism development, strengthening its competitiveness and increasing the efficiency of the activities it covers, there must be timely statistical information available ensuring data comparability, completeness and detailing. This paper presents the methodological foundations of tourism satellite accounts. The emphasis is placed on their significance as a source of reliable and comparable statistical information on the importance of tourism for the economy in terms of expenditure, employment and gross domestic product. The contents of the tables containing data on tourism by activity and products are discussed and the theoretical aspects are illustrated through the empirical study of tourism expenditure (resident and non-resident visitors) in Bulgaria. Statistical methods of analysis are used to study the changes in their size and structure for the period 2008-2014.Для розробки управлінських рішень, що сприяють сталому розвитку туризму, утвердженню його конкурентоспроможності та підвищенню ефективності видів діяльності, що входять в його охоплення, необхідна наявність своєчасно наданої статистичної інформації, яка гарантує сумісність, повноту і деталізацію даних. У публікації представлено методологічні основи сателітних рахунків туризму. Акцентується увага на їх значенні як джерела достовірної і порівнянної статистичної інформації про значимість туризму для економіки з точки зору витрат, зайнятості та валового внутрішнього продукту. Розглядається зміст таблиць, які надають дані про туризм за видами діяльності і продуктів. Теоретичні аспекти проілюстровані емпіричним дослідженням витрат на кінцеве споживання туристів (резидентів і нерезидентів) в Болгарії. За допомогою статистичних методів аналізу досліджено зміни їх розміру і структури за період 2008-2014 рр.Для разработки управленческих решений, способствующих устойчивому развитию туризма, утверждению его конкурентоспособности и повышению эффективности видов деятельности, входящих в его охват, необходимо наличие своевременно предоставляемой статистической информации, гарантирующей сопоставимость, полноту и детализацию данных. В публикации представлены методологические основы сателлитных счетов туризма. Акцентируется внимание на их значении в качестве источника достоверной и сравнимой статистической информации о значимости туризма для экономики с точки зрения расходов, занятости и валового внутреннего продукта. Рассматривается содержание таблиц, предоставляющих данные о туризме по видам деятельности и продуктам. Теоретические аспекты проиллюстрированы эмпирическим исследованием расходов на конечное потребление туристов (резидентов и нерезидентов) в Болгарии. Посредством статистических методов анализа исследованы изменения их размера и структуры за период 2008-2014 гг
CMS endcap RPC gas gap production for upgrade
The CMS experiment will install a RE4 layer of 144 new Resistive Plate Chambers (RPCs) on the existing york YE3 at both endcap regions to trigger high momentum muons from the proton-proton interaction. In this paper, we present the detailed procedures used in the production of new RPC gas gaps adopted in the CMS upgrade. Quality assurance is enforced as ways to maintain the same quality of RPC gas gaps as the existing 432 endcap RPC chambers that have been operational since the beginning of the LHC operation
Performance of the Gas Gain Monitoring system of the CMS RPC muon detector and effective working point fine tuning
The Gas Gain Monitoring (GGM) system of the Resistive Plate Chamber (RPC)
muon detector in the Compact Muon Solenoid (CMS) experiment provides fast and
accurate determination of the stability in the working point conditions due to
gas mixture changes in the closed loop recirculation system. In 2011 the GGM
began to operate using a feedback algorithm to control the applied voltage, in
order to keep the GGM response insensitive to environmental temperature and
atmospheric pressure variations. Recent results are presented on the feedback
method used and on alternative algorithms
The Upgrade of the CMS RPC System during the First LHC Long Shutdown
The CMS muon system includes in both the barrel and endcap region Resistive
Plate Chambers (RPC). They mainly serve as trigger detectors and also improve
the reconstruction of muon parameters. Over the years, the instantaneous
luminosity of the Large Hadron Collider gradually increases. During the LHC
Phase 1 (~first 10 years of operation) an ultimate luminosity is expected above
its design value of 10^34/cm^2/s at 14 TeV. To prepare the machine and also the
experiments for this, two long shutdown periods are scheduled for 2013-2014 and
2018-2019. The CMS Collaboration is planning several detector upgrades during
these long shutdowns. In particular, the muon detection system should be able
to maintain a low-pT threshold for an efficient Level-1 Muon Trigger at high
particle rates. One of the measures to ensure this, is to extend the present
RPC system with the addition of a 4th layer in both endcap regions. During the
first long shutdown, these two new stations will be equipped in the region
|eta|<1.6 with 144 High Pressure Laminate (HPL) double-gap RPCs operating in
avalanche mode, with a similar design as the existing CMS endcap chambers.
Here, we present the upgrade plans for the CMS RPC system for the fist long
shutdown, including trigger simulation studies for the extended system, and
details on the new HPL production, the chamber assembly and the quality control
procedures.Comment: 9 pages, 6 figures, presented by M.Tytgat at the XI workshop on
Resistive Plate Chambers and Related Detectors (RPC2012), INFN - Laboratori
Nazionali di Frascati, February 5-10, 201
Optical detection of single non-absorbing molecules using the surface plasmon of a gold nanorod
Current optical detection schemes for single molecules require light
absorption, either to produce fluorescence or direct absorption signals. This
severely limits the range of molecules that can be detected, because most
molecules are purely refractive. Metal nanoparticles or dielectric resonators
detect non-absorbing molecules by a resonance shift in response to a local
perturbation of the refractive index, but neither has reached single-protein
sensitivity. The most sensitive plasmon sensors to date detect single molecules
only when the plasmon shift is amplified by a highly polarizable label or by a
localized precipitation reaction on the particle's surface. Without
amplification, the sensitivity only allows for the statistical detection of
single molecules. Here we demonstrate plasmonic detection of single molecules
in realtime, without the need for labeling or amplification. We monitor the
plasmon resonance of a single gold nanorod with a sensitive photothermal assay
and achieve a ~ 700-fold increase in sensitivity compared to state-of-the-art
plasmon sensors. We find that the sensitivity of the sensor is intrinsically
limited due to spectral diffusion of the SPR. We believe this is the first
optical technique that detects single molecules purely by their refractive
index, without any need for photon absorption by the molecule. The small size,
bio-compatibility and straightforward surface chemistry of gold nanorods may
open the way to the selective and local detection of purely refractive proteins
in live cells
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