Pyroclastic flow dynamics and hazard in a caldera setting: application to Phlegrean Fields

Numerical simulation of pyroclastic density currents has developed significantly in recent years and is increasingly applied to volcanological research. Results from physical modeling are commonly taken into account in volcanic hazard assessment and in the definition of hazard mitigation strategies. In this work, we modeled pyroclastic density currents in the Phlegrean Fields caldera, where flows propagating along the flat ground could be confined by the old crater rims that separate downtown Naples from the caldera. The different eruptive scenarios (mass eruption rates, magma compositions, and water contents) were based on available knowledge of this volcanic system, and appropriate vent conditions were calculated for each scenario. Simulations were performed along different topographic profiles to evaluate the effects of topographic barriers on flow propagation. Simulations highlighted interesting features associated with the presence of obstacles such as the development of backflows. Complex interaction between outward moving fronts and backflows can affect flow propagation; if backflows reach the vent, they can even interfere with fountain dynamics and induce a more collapsing behavior. Results show that in the case of large events ( 108 kg/s), obstacles affect flow propagation by reducing flow velocity and hence dynamic pressure in distal regions, but they cannot stop the advancement of flows. Deadly conditions (in terms of temperature and ash concentration) characterize the entire region invaded by pyroclastic flows. In the case of small events (2.5 107 kg/s), flows are confined by distal topographic barriers which provide valuable protection to the region beyond

Critical analysis of the manoeuvres proposed for the diagnosis of the tunnel carpal syndrome

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy. It is mainly due to the compression of median nerve at the wrist and it may be idiopathic or secondary to different rheumatic or non rheumatic diseases, including occupational activities. Since signs and symptoms of CTS are characteristic, a careful examination of the affected patient may be very satisfactory for the diagnosis, in particular by mean of some manoeuvres. In this review we described and commented the tests considered most useful in the diagnosis of CTS. We also analysed the diagnostic values of electromiography, the most important electrodiagnostic study for the CTS

Models and experimental results from the wide aperture Nb-Ti magnets for the LHC upgrade

MQXC is a Nb-Ti quadrupole designed to meet the accelerator quality requirements needed for the phase-1 LHC upgrade, now superseded by the high luminosity upgrade foreseen in 2021. The 2-m-long model magnet was tested at room temperature and 1.9 K. The technology developed for this magnet is relevant for other magnets currently under development for the high-luminosity upgrade, namely D1 (at KEK) and the large aperture twin quadrupole Q4 (at CEA). In this paper we present MQXC test results, some of the specialized heat extraction features, spot heaters, temperature sensor mounting and voltage tap development for the special open cable insulation. We look at some problem solving with noisy signals, give an overview of electrical testing, look at how we calculate the coil resistance during at quench and show that the heaters are not working We describe the quench signals and its timing, the development of the quench heaters and give an explanation of an Excel quench calculation and its comparison including the good agreement with the MQXC test results. We propose an improvement to the magnet circuit design to reduce voltage to ground values by factor 2. The program is then used to predict quench Hot-Spot and Voltages values for the D1 dipole and the Q4 quadrupole.Comment: 8 pages, Contribution to WAMSDO 2013: Workshop on Accelerator Magnet, Superconductor, Design and Optimization; 15 - 16 Jan 2013, CERN, Geneva, Switzerlan

Insertion Magnets

Chapter 3 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary Design Report. The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community of about 7,000 scientists working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will need a major upgrade in the 2020s. This will increase its luminosity (rate of collisions) by a factor of five beyond the original design value and the integrated luminosity (total collisions created) by a factor ten. The LHC is already a highly complex and exquisitely optimised machine so this upgrade must be carefully conceived and will require about ten years to implement. The new configuration, known as High Luminosity LHC (HL-LHC), will rely on a number of key innovations that push accelerator technology beyond its present limits. Among these are cutting-edge 11-12 tesla superconducting magnets, compact superconducting cavities for beam rotation with ultra-precise phase control, new technology and physical processes for beam collimation and 300 metre-long high-power superconducting links with negligible energy dissipation. The present document describes the technologies and components that will be used to realise the project and is intended to serve as the basis for the detailed engineering design of HL-LHC.Comment: 19 pages, Chapter 3 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary Design Repor

Anomalous Couplings in Double Higgs Production

The process of gluon-initiated double Higgs production is sensitive to non-linear interactions of the Higgs boson. In the context of the Standard Model, studies of this process focused on the extraction of the Higgs trilinear coupling. In a general parametrization of New Physics effects, however, an even more interesting interaction that can be tested through this channel is the (ttbar hh) coupling. This interaction vanishes in the Standard Model and is a genuine signature of theories in which the Higgs boson emerges from a strongly-interacting sector. In this paper we perform a model-independent estimate of the LHC potential to detect anomalous Higgs couplings in gluon-fusion double Higgs production. We find that while the sensitivity to the trilinear is poor, the perspectives of measuring the new (ttbar hh) coupling are rather promising.Comment: 22 pages, 9 figures. v2: plots of Figs.8 and 9 redone to include experimental uncertainty on the Higgs couplings, references adde

Isolated congenital heart block in undifferentiated connective tissue disease and in primary Sjögren's syndrome: a clinical study of 81 pregnancies in 41 patients

Objective: To study the incidence and the features of congenital heart block (CHB) in patients with undifferentiated connective tissue disease (UCTD) and primary Sjögren's syndrome (pSS). Methods: We studied 81 pregnancies of 41 women attending the Outpatients' Clinic of the Rheumatology Unit of University Hospital of Padova from July 1989 to March 2004. Twenty five of these (61%) were affected with UCTD and 16 (39%) with pSS. Serologic inclusion criteria was anti-Ro/La positivity, assessed by counterimmunoelectrophoresis and ELISA. Results: CHB was found in 2 out of the 46 (4,3%) pregnancies followed by our Staff and in 2 out of the 35 (5,7%) included in the retrospective part of the study. In 3 cases CHB was a 3rd degree block, causing pregnancy termination in 2. The only 2nd degree block was identified in one patient at the 22nd week of gestation and treated with dexamethasone and plasma-exchange. All of the women were positive to 52 kd and 60 kd Ro autoantibodies. CHB mothers had higher titer antibodies to 52 kd Ro protein than did the mothers with healthy infants (P = 0,026). Electrocardiographic abnormalities at birth were found in 3 out of 29 asymptomatic infants. One presented sinus bradycardia, the second abnormalities of ventricular repolarization, both regressed spontaneously, while the third ventricular extrasystoles which continue even now at 5 months. Conclusion: These results showed that in UCTD and pSS there is a higher incidence of CHB than that reported in Systemic Lupus Erythematosus. Electrocardiographic screening in all infants born to mothers with anti-Ro/La antibodies would seem an important measure to identify those with irreversible heart conduction abnormalities

Performance of the First Short Model 150-mm-Aperture Nb3Sn Quadrupole MQXFS for the High-Luminosity LHC Upgrade

The U.S. LHC Accelerator Research Program (LARP) and CERN combined their efforts in developing Nb Sn magnets for the high-luminosity LHC upgrade. The ultimate goal of this collaboration is to fabricate large aperture Nb Sn quadrupoles for the LHC interaction regions. These magnets will replace the present 70-mm-Aperture NbTi quadrupole triplets for expected increase of the LHC peak luminosity up to 5 × 10 cm s or more. Over the past decade, LARP successfully fabricated and tested short and long models of 90 and 120-mm-Aperture Nb Sn quadrupoles. Recently, the first short model of 150-mm-diameter quadrupole MQXFS was built with coils fabricated both by LARP and CERN. The magnet performance was tested at Fermilab's vertical magnet test facility. This paper reports the test results, including the quench training at 1.9 K, ramp rate and temperature dependence, as well as protection heater studies. 3 3 3 34 -2 -

Accelerator Physics Code Web Repository

In the framework of the CARE HHH European Network, we have developed a web-based dynamic acceleratorphysics code repository. We describe the design, structure and contents of this repository, illustrate its usage, and discuss our future plans, with emphasis on code benchmarking

Progress on HL-LHC Nb3Sn Magnets

The high-luminosity Large Hadron Collider (HL-LHC) project aims at allowing to increase the collisions in the LHC by a factor of ten in the decade 2025-2035. One essential element is the superconducting magnet around the interaction region points, where the large aperture magnets will be installed to allow to further reduce the beam size in the interaction point. The core of this upgrade is the Nb Sn triplet, made up of 150-mm aperture quadrupoles in the range of 7-8 m. The project is being shared between the European Organization for Nuclear Research and the US Accelerator Upgrade Program, based on the same design, and on the two strand technologies. The project is ending the short model phase, and entering the prototype construction. We will report on the main results of the short model program, including the quench performance and field quality. A second important element is the 11 T dipole that replaces a standard dipole making space for additional collimators. The magnet is also ending the model development and entering the prototype phase. A critical point in the design of this magnet is the large current density, allowing increase of the field from 8 to 11 T with the same coil cross section as in the LHC dipoles. This is also the first two-in-one Nb Sn magnet developed so far. We will report the main results on the test and the critical aspects. 3