Observation of multiple volume reflection by different planes in one bent silicon crystal for high-energy negative particles

Multiple volume reflection by different planes passing through the ?111? axis in a bent silicon crystal was observed for the first time for 150 GeV/c negative particles, ? - mesons, at one of the secondary beams of the CERN SPS. The beam of ? - mesons was deflected opposite to the crystal bend by an angle of about 48 ?rad, which is 4.6 times larger than in a single volume reflection by the (110) bent planes. The one-side deflection efficiency was about 65%. Multiple volume reflection transforms to a single volume reflection when the orientation angle of the ?111? axis relative to the beam direction is increased. Copyright © 2011 Europhysics Letters Association.