3,200 research outputs found

    New critical behavior in unconventional ferromagnetic superconductors

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    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

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    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

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    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 κ\kappa 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 Hc0H_{c0} rather than in materials with small κ\kappa. 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

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    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


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    CMS endcap RPC gas gap production for upgrade

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    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

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    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

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    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

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    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