Experimental results of the laserwire emittance scanner for LINAC4 at CERN

Abstract

Diamond Fibre optics a b s t r a c tWithin the framework of the LHC Injector Upgrade (LIU), the new LINAC4 is currently being commissioned to replace the existing LINAC2 proton source at CERN. After the expected completion at the end of 2016, the LINAC4 will accelerate H À ions to 160 MeV. To measure the transverse emittance of the H À beam, a method based on photo-detachment is proposed. This system will operate using a pulsed laser with light delivered via an optical fibre and subsequently focused onto the H À beam.

Demonstration of a laserwire emittance scanner for hydrogen ion beams at CERN

“…The variation of the electrostatic field inside the diamond could thus lead to a decreased charge collection efficiency (CCE) during the LINAC macropulse. This might also explain the signal amplitude of just a few mV, which is two orders of magnitude lower than expected by calculations not considering the effects of the proton implantation [18]. This disturbance is supposed to be negligible for higher beam energies (starting from 12 MeV) for which the protons have high probability to traverse and escape the diamond bulk without being stopped.…”

“…A bandwidth of min. 20 MHz is required to record the beam pulse with negligible distortion [18]. To achieve a reasonable electrical signal the detector also needs to have internal gain.…”