In this paper, we outline the present status of the design studies for the high-luminosity Large Hadron Collider, focusing on the choice of the aperture of the inner triplet quadrupoles. After ...reviewing some critical aspects of the design such as energy deposition, shielding, heat load, and protection, we present the main tentative parameters for building a 150-mm-aperture Nb 3 Sn quadrupole, based on the experience gathered by the LARP program in the past several years.
An optical limiting sensor working in the infrared (IR) was developed to address the need for eye and sensor protection against laser threats. Metallic and dielectric photonic resonators (thin-film ...multilayers) incorporating phase-change-materials, such as vanadium dioxide (VO 2 ) were simulated and experimentally realized, with optimization of the deposition procedure by RF magnetron sputtering at low temperature. For the first time, the silver is placed between the substrate and the VO 2 , thus improving the device limiting performances. By maximizing the difference of transmittance between the '' on '' and the '' off '' states at the standard light wavelength for telecom applications (1550 nm), we calculated optimum thickness for VO 2 and silver films. The deposited thin films were characterized by SEM and Raman spectroscopy, and VO 2 transition temperature was investigated by measuring resistance changes. As a proof of concept of the device working principle, we calculated transmittance drop of 70% when the sensor is exposed to a laser pulse excitation (20 ps, 500 MW/cm 2 ). Our results pave the way for multilayer with optical limiting properties.
The Large Hadron Collider Luminosity upgrade (HiLumi) program requires new low-β triplet quadrupole magnets, called MQXF, in the interaction region to increase the LHC peak and integrated luminosity. ...The MQXF magnets, designed and fabricated in collaboration between CERN and the U.S. LARP, will all have the same cross section. The MQXF long model, referred as MQXFA, is a quadrupole using the Nb3Sn superconducting technology with 150 mm aperture and a 4.2 m magnetic length and is the first long prototype of the final MQXF design. The MQXFA magnet is based on the previous LARP HQ and MQXFS designs. In this paper, we present the baseline design of the MQXFA structure with detailed three-dimensional (3-D) numerical analysis. A detailed tolerance analysis of the baseline case has been performed by using a 3-D finite element model, which allows fast computation of structures modeled with actual tolerances. Tolerance sensitivity of each component is discussed to verify the actual tolerances to be achieved by vendors. Tolerance stack-up analysis is presented in the end of this paper.
As part of the Large Hadron Collider (LHC) Luminosity upgrade program, the U.S.-LHC Accelerator Research Program collaboration and CERN are working together to design and build a 150-mm aperture Nb 3 ...Sn quadrupole for the LHC interaction regions. A first series of 1.5-m-long coils was fabricated and assembled in a first short model. A detailed visual inspection of the coils was carried out to investigate cable dimensional changes during heat treatment and the position of the windings in the coil straight section and in the end region. The analyses allow identifying a set of design changes which, combined with a fine tune of the cable geometry and a field quality optimization, were implemented in a new second-generation coil design. In this paper, we review the main characteristics of the first generation coils, describe the modification in coil layout and discuss their impact on parts design and magnet analysis.
In preparation for the high-luminosity upgrade of the Large Hadron Collider (LHC), the LHC Accelerator Research Program (LARP) in collaboration with CERN is pursuing the development of MQXF: a ...150-mm-aperture high-field Nb3Sn quadrupole magnet. The development phase starts with the fabrication and test of several short models (1.2-m magnetic length) and will continue with the development of several long prototypes. All of them are mechanically supported using a shell-based support structure, which has been extensively demonstrated on several R&D models within LARP. The first short model MQXFS-AT has been assembled at LBNL with coils fabricated by LARP and CERN. In this paper, we summarize the assembly process and show how it relies strongly on experience acquired during the LARP 120-mm-aperture HQ magnet series. We present comparison between strain gauges data and finite-element model analysis. Finally, we present the implication of the MQXFS-AT experience on the design of the long prototype support structure.
Nb3Sn superconducting wires made by the restacked-rod process (RRP registered ) were found to have a dramatically improved resilience to axial tensile strain when alloyed with Ti as compared to Ta. ...Whereas Ta-alloyed Nb3Sn in RRP wires showed permanent damage to its current-carrying capacity (Ic) when tensioned beyond an intrinsic strain as small as 0.04%, Ti-doped Nb3Sn in RRP strands exhibits a remarkable reversibility up to a tensile strain of about 0.25%, conceivably making Ti-doped RRP wires more suitable for the high field magnets used in particle accelerators and nuclear magnetic resonance applications where mechanical forces are intense. A strain cycling experiment at room temperature caused a significant drop of Ic in Ta-alloyed wires, but induced an increase of Ic in the case of Ti-doped strands. Whereas either Ti or Ta doping yield a similar enhancement of the upper critical field of Nb3Sn, the much improved mechanical behavior of Ti-alloyed wires possibly makes Ti a better choice over Ta, at least for the RRP wire processing technique.
The Fermilab Mu2e experiment has been developed to search for evidence of charged lepton flavor violation through the direct conversion of muons into electrons. The transport solenoid is an s-shaped ...magnet that guides the muons from the source to the stopping target. It consists of 52 superconducting coils arranged in 27 coil modules. A full-size prototype coil module, with all the features of a typical module of the full assembly, was successfully manufactured by a collaboration between INFN-Genoa and Fermilab. The prototype contains two coils that can be powered independently. To validate the design, the magnet went through an extensive test campaign. Warm tests included magnetic measurements with a vibrating stretched wire and electrical and dimensional checks. The cold performance was evaluated by a series of power tests and temperature dependence and minimum quench energy studies.
In high field magnet applications, Nb 3 Sn coils undergo a heat treatment step after winding. During this stage, coils radially expand and longitudinally contract due to the Nb 3 Sn phase change. In ...order to prevent residual strain from altering superconducting performances, the tooling must provide the adequate space for these dimensional changes. The aim of this paper is to understand the behavior of cable dimensions during heat treatment and to provide estimates of the space to be accommodated in the tooling for coil expansion and contraction. This paper summarizes measurements of dimensional changes on strands, single Rutherford cables, cable stacks, and coils performed between 2013 and 2015. These samples and coils have been performed within a collaboration between CERN and the U.S. LHC Accelerator Research Program to develop Nb 3 Sn quadrupole magnets for the HiLumi LHC. The results are also compared with other high field magnet projects.
OBJECTIVES: To analyze therapeutic pathways of patients with HF, and to estimate healthcare resources consumption. METHODS: An observational retrospective cohort analysis based on administrative ...databases of 1 Local Health Unit in Italy was performed. Patients ≥18 with a hospitalization discharge diagnosis of HF (ICD-9-CM 428.xx; 402.xx) from January 1st, 2010 to December 31st, 2014 (inclusion period) were included.The index-date (ID) was the first hospitalization for HF during inclusion period. All patients were characterized 12 months prior the ID and followed up after the ID for 12 months. Patients were excluded if not treated with specific drugs as: ACE-inhibitors, ARBs, diuretics, digitalics, beta-blockers. Two cohorts were built: patients with HF as primary and patients with HF as secondary diagnosis. RESULTS: A total of 2,669 patients with HF were enrolled in the study, 1,960 as primary and 709 as secondary diagnosis. About 49% and 55% males, mean age of 77.0±10.4/76.5±11.1 years in both cohorts. Mortality during 12 months of follow-up was 46% and 43% respectively. Charlson Index score was >0 for more than 90% of patients. In follow-up period, half of the patients present a switch from the original therapy, 10% of the patients requires an add-on. Healthcare resource consumption for patients discharged alive is 11,9006" for patients with primary diagnosis and 12,500f for patients with secondary diagnosis. Cost for a hospitalization is around 3,600€ for HF patients in primary diagnosis and 4,200€ in secondary diagnosis. CONCLUSIONS: Our findings highlight that, in real-world setting, HF has a strong impact on National Health Service. During follow-up period, a high percentage of patients were under-treated, more of half of the patients changed their therapy or added drugs. A big effort, by cardiologist should be done to give the right therapies to the right patients, in order to improve therapeutic pathways and quality life.
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