As a result of the excellent quality of the Large Hadron Collider (LHC) experimental detectors and the accurate calibration of the luminosity at the LHC, uncertainties on the LHC beam energy may ...contribute significantly to the measurement errors on certain observables unless the relative uncertainty is well below 1%. Direct measurements of the beam energy using the revolution frequency difference of proton and lead beams combined with the magnetic model errors are used to provide the energy uncertainty of the LHC beams. Above injection energy the relative uncertainty on the beam energy is determined to be ±0.1% . The energy values as reconstructed and distributed online to the LHC experiments do not require any correction above injection energy. At injection a correction of +0.31GeV/c must be applied to the online energy values.
Advanced Accelerator Magnets for Upgrading the LHC Bottura, L.; de Rijk, G.; Rossi, L. ...
IEEE transactions on applied superconductivity,
06/2012, Letnik:
22, Številka:
3
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The Large Hadron Collider is working at about half its design value, limited by the defective splices of the magnet interconnections. While the full energy will be attained after the splice ...consolidation in 2014, CERN is preparing a plan for a Luminosity upgrade (High Luminosity LHC) around 2020 and has launched a pre-study for exploring an Energy upgrade (High Energy LHC) around 2030. Both upgrades strongly rely on advanced accelerator magnet technology, requiring dipoles and quadrupoles of accelerator quality and operating fields in the 11-13 T range for the luminosity upgrade and 16-20 T range for the energy upgrade. The paper will review the last ten year of Nb 3 Sn accelerator magnet R&D and compare it to the needs of the upgrades and will critically assess the results of the Nb 3 Sn and HTS technology and the planned R&D programs also based on the inputs of first year of LHC operation.
The design of future circular high-energy hadron colliders is based on the achievement of challenging magnetic fields, needed to keep the hadron beams orbiting along the ring circumference. The ...strength of the dipolar magnetic field is a function of the machine radius, beam energy, and of the fraction of the ring circumference that can be filled with dipoles. In this paper, we propose to use a combined-function periodic cell to maximise the filling factor of the dipole magnets. The optical properties of the proposed periodic structure are discussed in detail together with the design of the superconducting magnets needed to implement the proposed approach.
Abstract
Background
Ribavirin is currently recommended for treating chronic hepatitis E virus (HEV) infection. This retrospective European multicenter study aimed to assess the sustained virological ...response (SVR) in a large cohort of solid organ transplant (SOT) recipients with chronic HEV infection treated with ribavirin monotherapy (N = 255), to identify the predictive factors for SVR, and to evaluate the impact of HEV RNA mutations on virological response.
Methods
Data from 255 SOT recipients with chronic HEV infection from 30 European centers were analyzed. Ribavirin was given at the median dose of 600 (range, 29–1200) mg/day (mean, 8.6 ± 3.6 mg/kg/day) for a median duration of 3 (range, 0.25–18) months.
Results
After a first course of ribavirin, the SVR rate was 81.2%. It increased to 89.8% when some patients were offered a second course of ribavirin. An increased lymphocyte count at the initiation of therapy was a predictive factor for SVR, while poor hematological tolerance of ribavirin requiring its dose reduction (28%) and blood transfusion (15.7%) were associated with more relapse after ribavirin cessation. Pretreatment HEV polymerase mutations and de novo mutations under ribavirin did not have a negative impact on HEV clearance. Anemia was the main adverse event.
Conclusions
This large-scale retrospective study confirms that ribavirin is highly efficient for treating chronic HEV infection in SOT recipients and shows that the predominant HEV RNA polymerase mutations found in this study do not affect the rate of HEV clearance.
This large-scale retrospective study that included 255 solid organ transplant recipients confirms that ribavirin is highly efficient for treating chronic hepatitis E virus (HEV) infection and shows that HEV RNA polymerase mutations do not play a role in HEV clearance.
The continuity of the 18, 13, and 2 kA circuits of the HL-LHC magnets heavily relies on splices and electrical connections, to which it is worth devoting a special attention from the early phases. ...This spans the design of the splice or connection itself, together with the tooling and related procedure, so that the execution can reliably yield high quality results. Mindful of the history of LHC splices, robustness and reproducibility of the execution solutions are two of the fundamental parameters that have guided the technical choices made during the development phase. The number of technical solutions considered is due to the variety of possible combinations, depending on the various nature and geometry of the superconducting cables to be joined together. This wide spectrum calls for a rigorous qualification protocol, including micrography, mechanical tests before and after fatigue stress and electrical tests at room and cryogenic temperature. The article will illustrate the choices made during the development phase for the 11 selected families of splices and electrical connections, together with their qualification process, while providing results and statistics from the mechanical and electrical tests campaigns.
The High Luminosity LHC (HL-LHC) project aims at accumulating 3000 fb -1 in the years 2023-2035, i.e., ten times more w.r.t. the nominal LHC performance expected for 2010-2021. One key element to ...reach this challenging performance is a new insertion region to reduce the beam size in the interaction point by approximately a factor two. This requires larger aperture magnets in the region spanning from the interaction point to the matching section quadrupoles. This aperture has been fixed to 150 mm for the inner triplet quadrupoles in 2012. In this paper, we give a first baseline of the interaction region. We discuss the main motivations that lead us to choose the technology, the combination of fields/gradients and lengths, the apertures, the quantity of superconductor, and the operational margin. Key elements are also the constraints given by the energy deposition in terms of heat load and radiation damage; we present the main features related to shielding and heat removal.
Summary
CD30 is a transmembrane protein from the tumour necrosis factor receptor superfamily. It is expressed on a small subset of activated T and B lymphocytes, and various lymphoid neoplasms. CD30 ...is a particularly interesting treatment target because its levels are high in tumours but low in healthy tissues. Several therapeutic strategies targeting CD30 have been developed, including monoclonal antibodies, conjugated antibodies (combination of brentuximab vedotin with chemotherapy or immunotherapy), bispecific antibodies and cell and gene therapies, such as anti‐CD30 CAR‐T cells in particular. We briefly review the biology of CD30 which makes it a good therapeutic target, and we describe all of the anti‐CD30 therapies that have emerged to date.
Fermilab is fabricating ten full length cold masses for the high-luminosity Large Hadron Collider Accelerator Upgrade Project (HL-LHC AUP). One practice assembly and one pre-series assembly have been ...completed. This paper summarizes the con-struction details. Topics include incoming inspection, bus assembly, component machining, shell forming, beam tube insertion, bus expansion loop installation, instrumentation installation, electrical testing, heat exchanger installation and final assembly welding. In-process surveys, alignment measurements and testing are presented and explained. Problems encountered during construction and their solutions are discussed.
To meet the milestones set by the High-Luminosity LHC (HL-LHC) project, the integration of new inner triplet magnet circuits is vital for enhancing the focusing of the particle beams at ATLAS and ...CMS. In addition to the Nb 3 Sn quadrupole magnets, high-order Nb-Ti magnets are required for field correction. This comprises self-protected magnets with six, eight, ten, and twelve poles, which also come in skewed variants. The simulation program LEDET was developed as part of the STEAM framework and is now applied to study quench transients in HL-LHC magnets. The electromagnetic and thermal transients occurring after a quench are simulated and validated with experiments at different current levels conducted by LASA (INFN). For the models, the three-dimensional geometry is accurately replicated and for each magnet the conductor parameters of each coil are set according to measurements. After discussing the various assumptions of the model, a simulation study is conducted to investigate the influence of the unknown quench location and inter-filament coupling losses. The developed models of each magnet show satisfactory accuracy and are predictive for different current levels. The models are then used to analyse the simulated hot-spot temperatures and peak voltages-to-ground, which cannot be easily measured. It is concluded that the protection strategy is effective.
The luminosity upgrade of the Large Hadron Collider involves large modifications of the magnets close to the interaction regions. In particular, the double-aperture separation/recombination dipoles ...D2 shall deliver a field integral of 35 <inline-formula> <tex-math notation="LaTeX">\text{T}\cdot\text{m}</tex-math></inline-formula>. Given the physical and geometrical constraints limiting the length to less than 10 m, these magnets must be superconducting and shall generate a magnetic field higher than 3.5 T. Since the magnetic field direction is identical in both apertures (105 mm each one), the magnetic field between the two apertures sums up to high values, locally saturating the shielding iron yoke surrounding both coils. In order to decouple the magnetic field in the two apertures, a strategy has been developed based on three pillars: 1) no iron is placed in between the coils (thus limiting saturation effects); 2) each coil is asymmetric in a way to cancel the magnetic crosstalk to each other; 3) the yoke is suitably profiled for minimizing the variation in the harmonic components due to iron saturation. Based on these concepts, a 2-D magnetic optimization was carried out, leading to an acceptable field quality with a limited variation of the multipoles as the magnet field is raised from the injection value to the maximum value (4.5 T). A 2-D mechanical design was also performed with the aim at simplifying the construction issues and keeping under control the parameters relevant to beam optics (beam separation and magnetic multipoles). Finally, the coil ends were designed, too, and a complete model 1.5 m long drafted. This paper discusses in detail all these aspects, with some considerations about the future developments preliminary to the mass production.
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