Laserwire emittance scanner at CERN LINAC4

Linac 4 presently under construction at CERN is designed to replace the existing 50 MeV Linac 2 in the LHC injector chain and will accelerate the beam of high current negative hydrogen ions to 160 MeV. During the commissioning a laserwire emittance scanner has been installed allowing noninvasive measuring of the emittance at 3 MeV and 12 MeV setups. A relatively low power infrared fibre coupled laser w a s focused in the interaction region down to ∼150 μm and collided with the ion beam neutralising negative ions. A t each transverse laser position with respect to the ion beam the angular distribution of the neutral particle beamlets w a s recorded b y scanning a diamond detector across the beamlet at a certain distance from the interaction point while the main beam of the H^- ions w a s deflected using the dipole magnet installed upstream the detector. Measuring the profile of the beamlet b y scanning the laser across the beam allows to directly measure the transverse phase-space distribution and reconstruct the transverse beam emittance. In this report w e will describe the analysis of the data collected during the 3 MeV and 12 MeV operation of the Linac 4. W e will discuss the hardware status and future plans.