Commissioning and first-year operational results of the MAX IV 3 GeV electron storage ring, the first synchrotron light source to make use of the multibend-achromat lattice to achieve ultralow emittance and high brightness, are presented.

Compact quadrupole magnets are required for the CCDTL (Cell-Coupled Drift Tube Linac) of Linac 4, a 160 MeV linear accelerator of negative hydrogen ions which will replace the old 50 MeV proton Linac2 at CERN.The magnets, of an overall physical length of 140 mm and an aperture diameter of 45 mm, are based on Sm2Co17 blocks and can provide an integrated gradient of up to 1.6 Tesla. The magnetic field quality is determined by 4 ferromagnetic pole tips, aligned together with the permanent magnets blocks inside a structure made in a single piece.Tuning bars allow to individually trim the magnetic flux provided by each pole, to correct possible differences between blocks and to modify the field gradient intensity within about 20% of the nominal value.The paper describes and discusses the design, manufacture and magnetic measurements of a first prototype magnet. The paper describes and discusses the design, manufacture and magnetic measurements of a first prototype magnet Index Terms-Permanent magnets, quadrupoles, Linac4.

A magnetic spectrometer has been developed for the AWAKE experiment at CERN in order to measure the energy distribution of bunches of electrons accelerated in wakefields generated by proton bunches in plasma. AWAKE is a proof-of-principle experiment for proton-driven plasma wakefield acceleration, using proton bunches from the SPS. Electron bunches are accelerated to O(1 GeV) in a rubidium plasma cell and then separated from the proton bunches via a dipole magnet. The dipole magnet also induces an energy-dependent spatial horizontal spread on the electron bunch which then impacts on a scintillator screen. The scintillation photons emitted are transported via three highly-reflective mirrors to an intensified CCD camera, housed in a dark room, which passes the images to the CERN controls system for storage and further analysis. Given the known magnetic field * Corresponding author at: UCL,