The electron accelerators for the AWAKE experiment at CERN—Baseline and Future Developments

Abstract The AWAKE collaboration prepares a proton driven plasma wakefield accelerationexperiment using the SPS beam at CERN. A long proton bunchextracted from the SPS interacts with a high power laser and a 10 m long rubidium vapor plasma cell to create strong wakefields allowing sustained electron acceleration. The electron beam to probe these wakefields is created by an electron acceleratorconsisting of an rf-gun and a booster structure. This electron source should provide beams with intensities between 0.1 and 1 nC, bunchlengths between 0.3 and 3 ps and an emittance of the order of 2 mm mrad. The booster structure should acceleratethe electrons to 16 MeV. The electron line includes a series of diagnostics (pepper-pot, BPMs, spectrometer, Faraday cupand screens) and an optical transfer linemerges the electron beam with the proton beam on the same axis. The installation of the electron line started in early 2017 and the commissioning will take place at the end of 2017. The first phase of operation is called RUN1. After the long shutdown of LHC a second phase for AWAKE is planned starting 2021 called RUN2. In this phase the aim is to demonstrate the accelerationof high quality electron beams therefore a bunchlength of the order of 100 fs rms is required corresponding to a fraction of the plasma wavelength. The AWAKE collaboration is studying the design of such an injector either based on classical rf-gun injectors or on laser wake-field acceleration. The focus for the RF acceleratoris on a hybrid design using an S-bandrf-gun and x-band bunchingand accelerationcavities. The layout of the current and the future electron acceleratorand transfer line, including the diagnostics will be presented.