Abstract
The High Luminosity Large Hadron Collider (HL-LHC) is the new flagship project of CERN. First endorsed in 2013 and approved in 2016, HL-LHC is an upgrade of the accelerator aiming to ...increase by a factor of ten the statistics of the LHC collisions at the horizon of 2035–2040. HL-LHC relies on cutting edge technologies: among them, large aperture superconducting magnets will replace the present hardware to allow a smaller beam size in two interaction points (IPs). The project involves the construction of about 150 magnets of six different types: the quadrupole triplet, two main dipoles and three orbit correctors. The triplet, manufactured at CERN and in the USA, will consist of 30 magnets based on Nb
3
Sn technology, with an operational peak field of 11.4 T. These will be the first quadrupole Nb
3
Sn magnets installed in a particle accelerator. The other five types of magnets, all relying on Nb–Ti technology, present non-trivial challenges in the design and construction; they will be manufactured as part of in-kind contribution under the responsibility of institutes in Japan, China, Spain, and Italy. The project is now in the phase of transition between qualification through short models and prototypes and the beginning of the series construction. In this paper we review the magnet requirements, the reasons for selecting the design, the technological challenges with respect to previous projects, and we summarize the steps that have been taken to validate the baseline.
At present, one of the main options for beam bending dipoles of the SIS 300 synchrotron, under design for the FAIR facility at GSI, is a single layer magnet 7.8 m long, 100 mm in bore diameter, ...generating 4.5 T. This coil has two main features: it is curved, with a curvature radius of 66.67 m (the corresponding sagitta is 114 mm), and shall be ramped at 1 T/s. Both these characteristics demand challenging R&D, aimed at the development of the required conductor and winding technology. The paper discusses both these aspects, in the frame of a general ongoing R&D program at INFN, under the name DISCORAP. Its goal is the construction of a short prototype (3.8 m) dipole, fully integrated into its horizontal cryostat, within three years. The R&D program includes: 1) the activities required to develop low loss superconducting wires and cable; 2) the technological developments (at the industrial level) for defining and optimizing the dipole constructing methods; 3) the construction of curved dipole coil winding models; 4) the construction of the complete curved dipole; 5) the test of the curved dipole in a vertical cryostat; 6) the integration of the curved dipole into a horizontal cryostat, for the final test at GSI.
INFN (Istituto Nazionale di Fisica Nucleare, Italy) has started in 2006 the DISCORAP project, which foresees the design, manufacture and test of a dipole prototype for the SIS-300 synchrotron of the ...FAIR facility at GSI. In order to minimize the losses produced by the fast ramp rate (1 T/s) at which the magnet is operated, we are developing with European industries, a Rutherford cable which incorporates several technologies to reduce the losses, and namely a NbTi filament diameter on the order of 2.5-3.5 mum, Cu 0.5 wt%Mn interfilamentary matrix and stainless steel core. In this paper we present the design principles and the first experimental results; we also analyze the impact of the CuMn paramagnetism on the field distortion at the different operating magnetic fields.
The benefits of anticoagulant therapy and antiplatelet agents in secondary prevention of myocardial infarction (MI) are well known. Administration of combined warfarin and aspirin (ASA) has not been ...well studied. The objective of this study was to compare the effect of coadministration of warfarin and ASA with administration of ASA alone on outcome of patients after MI. One hundred forty age- and sex-matched survivors of MI were randomized to receive either 100 mg/day ASA plus enough warfarin to reach a target: international normalized ratio of 2.5 (range: 2-3) (group A, n = 70), or only 100 mg/day ASA (group B, n = 70). The patients were examined for several variables including development of hemorrhage, reinfarction, and rehospitalization for 1 year post MI. Of the variables studied, minor hemorrhagic episodes were observed significantly (p = 0.002) more in group A than in group B patients. Rehospitalization and reinfarction rates, although occurring with lower frequencies in group A than in group B, did not reach the statistical significance level. In postmyocardial infarction patients, warfarin plus ASA did not provide a clinical benefit beyond that achievable with aspirin monotherapy, and for the observed markedly higher incidence of minor hemorrhage in combination therapy, antiplatelet therapy alone seems to be a more reasonable approach.
Design activities coupled with conductor R&D and model coil construction are under way for developing a curved fast cycled superconducting dipole suitable for operations of the SIS300 synchrotron at ...FAIR. The main target is the construction within 2009 of a model magnet (cold mass fully integrated in a horizontal cryostat). This magnet is designed for generating 4.5 T magnetic field in a bore of 100 mm, able to be operated at a field rate of 1 T/s. The magnetic length is 3.8 m with a curvature radius of 66.67 m (the sagitta is 27 mm). The mechanical structure is based on 3 mm thick laminated stainless steel collars, assembled through keys, and 1 mm thick iron yoke laminations, assembled through large Al alloy C-shaped clamps. A 2D finite element analysis has been performed to evaluate stresses and deformations coming out during assembly, cool-down and energization. Particular emphasis has been given to the possible fatigue problems ensuing from the large operating field rate over a large lifetime cycle number, 107. Numerical results are presented and discussed.
Developed within the INFN LASA and CERN collaboration agreement for the construction of the High Order Corrector Magnets for the High Luminosity-LHC project, the first half section of the Round Coil ...Superferric Magnet proved the feasibility of a new compact and modular corrector magnet type using MgB 2 superconductor. Different from the classic superferric layout, its unconventional design exploits the iron permeability to shape, with an arbitrary number of poles, the solenoidal field created by a large bending radius coil suitable for strain-sensitive superconductors. After the design upgrade of the winding and impregnation process, in this paper, we describe the realization of the second superconducting coil for the full module length prototype of the sextupole corrector. The integration of the two half-sections of the magnet module is analyzed in detail and the performances of the newer one, during tests at cryogenic temperature, are compared with the older results. Finally, the powering test of the full module and its magnetic field characterization are described and compared with the electromagnetic simulations and expected performances.
Accuracy of children's pain memories Zonneveld, L N; McGrath, P J; Reid, G J ...
Pain (Amsterdam),
07/1997, Letnik:
71, Številka:
3
Journal Article
Recenzirano
Despite its importance in clinical practice, little research has examined memory for pain in children. This prospective study tried to justify the use of children's pain recall in clinical practice. ...The purpose of this study was to (a) investigate the accuracy of children's recall of their worst and average pain intensity when controlling for the effects of repeated pain measurement and (b) examine the influence of children's anxiety, age, general memory ability and pain coping strategies on this accuracy. The accuracy of children's recalled pain intensities was studied in 55 inpatients aged 5-16 years by comparing the level of recorded pain intensity with the level of recalled pain intensity 1 day and 1 week after recording using Bieri's Faces Pain Scale. The accuracy of children's recalled pain intensities was high and showed little decrement over 1 week. Older children had more accurate recall of their worst pain intensity. Anxiety, general memory ability and pain coping strategies were not related to accuracy of recalled pain intensities.
Developed within the INFN LASA and CERN collaboration agreement for the construction of the High Order Corrector Magnets for the High Luminosity-LHC project, the first half section of the Round Coil ...Superferric Magnet proved the feasibility of a new compact and modular corrector magnet type using MgBFormula Omitted superconductor. Different from the classic superferric layout, its unconventional design exploits the iron permeability to shape, with an arbitrary number of poles, the solenoidal field created by a large bending radius coil suitable for strain-sensitive superconductors. After the design upgrade of the winding and impregnation process, in this paper, we describe the realization of the second superconducting coil for the full module length prototype of the sextupole corrector. The integration of the two half-sections of the magnet module is analyzed in detail and the performances of the newer one, during tests at cryogenic temperature, are compared with the older results. Finally, the powering test of the full module and its magnetic field characterization are described and compared with the electromagnetic simulations and expected performances.
Design activities, conductor R&D and model coil construction are under way for developing a curved fast cycled superconducting dipole for the SIS300 synchrotron at FAIR. The main target is the ...construction within year 2009 of a half-length model magnet (cold mass fully integrated in a horizontal cryostat). This magnet is designed for a maximum central field of 4.5 T in a bore of 100 mm, with a ramp rate of 1 T/s. The magnetic length of the prototype is 3.8 m with a curvature radius of 66.67 m (27 mm of sagitta). This paper describes the electromagnetic design of the coil-ends of the magnet. Particular emphasis is given to the study of the losses due to the eddy currents in collar and yoke, and to the other losses during the cycling of the magnet. The study has been performed with finite element codes, and it allowed to optimize the configuration in order to minimize both the peak field on the conductor and the total losses.
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