Superconducting rf (SRF) cavities are traditionally fabricated from superconducting material sheets or made of copper coated with superconducting material, followed by trim machining and electron-beam welding. An alternative technique to traditional shaping methods, such as deep-drawing and spinning, is electrohydraulic forming (EHF). InEHF, half-cells are obtained through ultrahigh-speed deformation of blank sheets, using shockwaves induced in water by a pulsed electrical discharge. With respect to traditional methods, such a highly dynamic process can yield interesting results in terms of effectiveness, repeatability, final shape precision, higher formability, and reduced springback. In this paper, the first results of EHFon high purity niobium are presented and discussed. The simulations performed in order to master the multiphysics phenomena of EHF and to adjust its process parameters are presented. The microstructures of niobium half-cells produced by EHF and by spinning have been compared in terms of damage created in the material during the forming operation. The damage was assessed through hardness measurements, residual resistivity ratio (RRR) measurements, and electron backscattered diffraction analyses. It was found that EHF does not worsen the damage of the material during forming and instead, some areas of the half-cell have shown lower damage compared to spinning. Moreover, EHF is particularly advantageous to reduce the forming time, preserve roughness, and to meet the final required shape accuracy.

The Large Hadron Collider (LHC) main interconnection splices consist of Rutherford-type cable splice and busbar stabilizer splices. Busbar stabilizer splices have been consolidated during the first long LHC shutdown by soldering additional Cu shunts. In view of the large number of quality controls (QCs) that were integrated in the splice consolidation process, efficient and unambiguous QC procedures needed to be developed. Direct-current electrical resistance measurements have been selected for the control of the busbar splices and the individual shunts. About 400 000 resistance measurements performed at room temperature before and after each consolidation step have been analyzed. The resistance of the consolidated splices is comparable with the resistance of continuous busbars without splice. Resistance changes during the consolidation process correspond to those calculated from the changes in Cu cross-sectional area.

Future accelerator magnets will need to reach a magnetic field in the 20 T range. Reaching such a magnetic field is a challenge only reachable using high temperature superconductor (HTS) material. The high current densities and stress levels needed to satisfy the design criterion of such magnets make YBaCuO superconductor the most appropriate candidate especially when produced using the IBAD route. The HFM EUCARD program is aimed at designing and manufacturing a dipole insert made of HTS material generating 6 T inside a Nb3Sn dipole of 13 T at 4.2 K. In the HTS insert, engineering current densities higher than 250 MA/m2 under 19 T are required to reach the performances. The stress level is consequently very high. The insert protection is also a critical issue as HTS shows low quench propagation velocity. The coupling with the Nb3Sn dipole makes the problem even more difficult. The magnetic and mechanical designs of the HTS insert will be presented as well as the technological developments underway to realize this compact dipole insert.

In the long LHC (Large Hadron Collider) shutdown in 2013 it is foreseen to intervene on all the 13 kA interconnections in order to guarantee the necessary margin and redundancy to provide safe LHC operation at 7 TeV per beam. This implies reinforcement of the present interconnection configuration including a new insulation scheme of the busbars. The purpose of the new insulation model is to provide dielectric insulation with at least the same performance as its predecessor currently installed in the LHC machine, but in addition to contain the Lorentz forces.This paper describes the analytic and empirical approach of development to reach a new insulation concept based on state of the art materials and manufacturing techniques.

A measurement of the $ZZ$ production cross section in proton-proton collisions at $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$ using data corresponding to an integrated luminosity of $1.02\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ recorded by the ATLAS experiment at the LHC is presented. Twelve events containing two $Z$ boson candidates decaying to electrons and/or muons are observed, with an expected background of $0.3\ifmmode\pm\else\textpm\fi{}0.3(\mathrm{stat}{)}_{\ensuremath{-}0.3}^{+0.4}(\mathrm{syst})$ events. The cross section measured in a phase-space region with good detector acceptance and for dilepton masses within the range 66 to 116 GeV is ${\ensuremath{\sigma}}_{ZZ\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}}^{\mathrm{fid}}={19.4}_{\ensuremath{-}5.2}^{+6.3}(\mathrm{stat}{)}_{\ensuremath{-}0.7}^{+0.9}(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.7(\mathrm{lumi})\text{ }\text{ }\mathrm{fb}$. The resulting total cross section for on-shell $ZZ$ production, ${\ensuremath{\sigma}}_{ZZ}^{\mathrm{tot}}={8.5}_{\ensuremath{-}2.3}^{+2.7}(\mathrm{stat}{)}_{\ensuremath{-}0.3}^{+0.4}(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.3(\mathrm{lumi})\text{ }\text{ }\mathrm{pb}$, is consistent with the standard model expectation of ${6.5}_{\ensuremath{-}0.2}^{+0.3}\text{ }\text{ }\mathrm{pb}$ calculated at the next-to-leading order in QCD. Limits on anomalous neutral triple gauge boson couplings are derived.

The accident in the LHC in September 2008 occurred in an interconnection between two magnets of the 13 kA dipole circuit. Successive measurements of the resistance of other interconnects revealed other defective joints, even though the SC cables were properly connected. These defective joints are characterized by a poor bonding between the SC cable and the copper stabilizer in combination with an electrical discontinuity in the copper stabilizer. A quench at the 7-13 kA level in such a joint can lead to a fast and unprotected thermal run-away and hence opening of the circuit. It has therefore been decided to operate the LHC at a reduced and safe current of 6 kA corresponding to 3.5 TeV beam energy until all defective joints are repaired. A task force is reviewing the status of all electrical joints in the magnet circuits and preparing for the necessary repairs. The principle solution is to resolder the worst defective joints and, in addition, to apply an electrical shunt made of copper across all joints with sufficient cross-section to guarantee safe 12-13 kA operation at 7-7.5 TeV. In this paper the various actions that have lead to this solution are presented.

A search for contact interactions has been performed using dimuon events recorded with the ATLAS detector in proton-proton collisions at $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$. The data sample corresponds to an integrated luminosity of $42\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$. No significant deviation from the standard model is observed in the dimuon mass spectrum, allowing the following 95% C.L. limits to be set on the energy scale of contact interactions: $\ensuremath{\Lambda}>4.9\text{ }\text{ }\mathrm{TeV}$ (4.5 TeV) for constructive (destructive) interference in the left-left isoscalar compositeness model. These limits are the most stringent to date for $\ensuremath{\mu}\ensuremath{\mu}qq$ contact interactions.