Proton extraction from the CERN-SPS by a bent crystal

An experiment is being performed at the CERN-SPS to study the feasibility of extracting protons from the halo of a 120 GeV stored beam by means of planar channeling in a 8.5 mrad bent silicon monocrystal. Two different techniques have been used to bring the protons into the crystal. In one case a kicker magnet was repeatedly energized to displace particles up to 100 microns inside the crystal front face. In the other case a continuous flux of impinging particles was obtained by powering electrostatic plates with a white noise excitation. In both cases we observed an extracted beam of channeled particles. The detection was performed with several large size scintillators, a fluorescent screen, a scintillation hodoscope, and a pair of microstrip gas chambers. Extraction efficiencies of the order of 10% were measured