Evaluation of the Transfer of Heat from the Coil of the LHC Dipole Magnet to Helium II

During operation of the Large Hadron Collider at CERN, heat will be generated inside the coils of its superconducting magnets as a consequence of ramping of magnetic field, and of the interaction of lost beam particles with the magnet mass. Heat has to be transferred from the conductor into the He II coolant and removed from the magnet environment. During the LHC R&D stage, this transfer has been extensively studied on simulated coil segments at CEA/Saclay, and by analyzing dynamic behavior of short model magnets at CERN. Owing to the importance of efficient cooling for the design of future superconducting accelerator magnets, study of heat transfer has been restored at CERN and in frame of the Next European Dipole Collaboration. The article features two recently performed works: 1. Attempt to analyze archived high ramp rate quench data of 1-m-long LHC model dipole magnets of the 2nd generation. 2. Development of a method for direct measurement of heat transfer on segments of production LHC dipole magnet coils

Stability Analysis of the LHC Cables for Transient Heat Depositions

The commissioning and the exploitation of the LHC require a good knowledge of the stability margins of the superconducting magnets with respect to beam induced heat depositions. Previous studies showed that simple numerical models are suitable to carry out stability calculations of multi-strands cables, and highlighted the relevance of the heat transfer model with the surrounding helium. In this paper we present a systematic scan of the stability margin of all types of LHC cables working at 1.9 Kagainst transient heat depositions. We specifically discuss the dependence of the stability margin on the parameters of the model, which provide an estimate of the uncertainty of the values quoted. The stability margin calculations have been performed using a zero-dimensional (0-D) numerical model, and a cooling model taking into account the relevant helium phases which may appear during a stability experiment: it includes Kapitza thermal resistance in superfluid He, boundary layer formation and heat transfer in He I, and considers the transition from nucleating boiling to film boiling during He gas formation

3D right ventricular strain: comparative analysis of Tetralogy of Fallot and atrial septal defect

International audienceBackground: Right ventricular (RV) function assessment is crucial in CHD patients, especially in atrial septaldefect (ASD) and Tetralogy of Fallot (TOF) patients. Indeed, prognosis is very different between TOF patientswith pulmonary regurgitation and ASD patients, and only little is known about 3D deformation in RV overload. Purpose: The aim of our study was to assess RV remodeling differences between ASD, TOF patients andcontrols. Methods: We performed a prospective case­control study. We included 10 patients with an ASD (mean age53.3±21y) and 10 with TOF (mean age 34.9±18y) who were older than 16 years old, and compared them toa control group free from any cardiovascular disease (N=44, mean age 42.5±15y). 3D transthoracic RVechocardiographic sequences were acquired. Myocardial tracking was performed by a semi­automaticcommercial software. Output RV meshes included spatial correspondences. They were post­processed to alignthe data temporally and extract local deformation. Global and local statistics provided deformation patterns foreach subgroup of subjects. Results: Overall, ASD and TOF patients had similar but reduced RV ejection fraction (respectively 44.3±10and 44.5±12 %) and dilated right ventricles (mean RV EDV 158.3±100 and 115.4±46mL) using 3D analysis.Similar RV global area strain (GAS), global longitudinal strain (GLS) and global circumferential strain (GCS)were observed between the two groups. Compared to controls, ASD patients had lower GAS (­22.2±8 vs­29.4±5%; p=0.01), lower GCS (­12.9±4 vs ­17.1±4%; p=0.009) but similar GLS (p=0.07). TOF patientshad also lower GAS (­25.1±6%; p=0.03) but lower GLS (­10.0±3%; p=0.01) and similar GCS (­15.5±4%;p=0.4) in comparison with the control group. However, ASD patients had significantly lower CS in theinfundibular, inlet and membranous septum as compared with TOF patients (respectively p=0.02, p=0.05 andp=0.03). Conclusion: Volume overload in ASD patients seems to impact circumferential strain and preserve longitudinalstrain, whereas TOF patients tend to have lower longitudinal strain with preserved circumferential strain,probably because of the combination of RV pressure and volume overload. A larger cohort of patients couldhelp understand the insights of RV remodeling in congenital heart disease using 3D speckle­tracking imagin

Dnmt2/Trdmt1 as mediator of RNA polymerase II transcriptional activity in cardiac growth

Dnmt2/Trdmt1 is a methyltransferase, which has been shown to methylate tRNAs. Deficient mutants were reported to exhibit various, seemingly unrelated, defects in development and RNA-mediated epigenetic heredity. Here we report a role in a distinct developmental regulation effected by a noncoding RNA. We show that Dnmt2-deficiency in mice results in cardiac hypertrophy. Echocardiographic measurements revealed that cardiac function is preserved notwithstanding the increased dimensions of the organ due to cardiomyocyte enlargement. Mechanistically, activation of the P-TEFb complex, a critical step for cardiac growth, results from increased dissociation of the negatively regulating Rn7sk non-coding RNA component in Dnmt2-deficient cells. Our data suggest that Dnmt2 plays an unexpected role for regulation of cardiac growth by modulating activity of the P-TEFb complex. © 2016 Ghanbarian et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

European Strategy for Particle Physics -- Accelerator R&D Roadmap

The 2020 update of the European Strategy for Particle Physics emphasised the importance of an intensified and well-coordinated programme of accelerator R&D, supporting the design and delivery of future particle accelerators in a timely, affordable and sustainable way. This report sets out a roadmap for European accelerator R&D for the next five to ten years, covering five topical areas identified in the Strategy update. The R&D objectives include: improvement of the performance and cost-performance of magnet and radio-frequency acceleration systems; investigations of the potential of laser / plasma acceleration and energy-recovery linac techniques; and development of new concepts for muon beams and muon colliders. The goal of the roadmap is to document the collective view of the field on the next steps for the R&D programme, and to provide the evidence base to support subsequent decisions on prioritisation, resourcing and implementation.Comment: 270 pages, 58 figures. Editor: N. Mounet. LDG chair: D. Newbold. Panel chairs: P. V\'edrine (HFM), S. Bousson (RF), R. Assmann (plasma), D. Schulte (muon), M. Klein (ERL). Panel editors: B. Baudouy (HFM), L. Bottura (HFM), S. Bousson (RF), G. Burt (RF), R. Assmann (plasma), E. Gschwendtner (plasma), R. Ischebeck (plasma), C. Rogers (muon), D. Schulte (muon), M. Klein (ERL