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

¹ CERN, European Organization for Nuclear Research - CH-1211 Geneva 23, Switzerland
² INFM-CNR - Via Vallotti 9, 25133 Brescia, Italy, EU
³ INFN, Sezione di Ferrara, Dipartimento di Fisica, Università di Ferrara - Via Saragat 1, 44100 Ferrara, Italy, EU
⁴ INFN, Laboratori Nazionali di Legnaro - Viale Università 2, 35020 Legnaro (PD), Italy, EU
⁵ Dipartimento di Ingegneria dei Materiali e Tecnologie Industriali, Università di Trento Via Mesiano 77, 38050 Trento, Italy, EU
⁶ INFN, Sezione di Trieste - Via Valerio 2, 34127 Trieste, Italy, EU
⁷ Institute of High Energy Physics - Moscow Region, RU-142284 Protvino, Russia
⁸ Joint Institute for Nuclear Research, Joliot-Curie 6 - 141980 Dubna, Moscow Region, Russia
⁹ Petersburg Nuclear Physics Institute - 188300 Gatchina, Leningrad Region, Russia
¹⁰ Università dell'Insubria - Via Valleggio 11, 22100 Como, Italy, EU
¹¹ INFN, Sezione di Milano Bicocca - Piazza della Scienza 3, 20126 Milano, Italy, EU
¹² Research Institute for Nuclear Problems, Belarusian State University - 220030, Minsk, Belarus

^a alexander.taratin@cern.ch

Received: 27 November 2010
Accepted: 9 February 2011

Abstract

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, π⁻ mesons, at one of the secondary beams of the CERN SPS. The beam of π⁻ mesons was deflected opposite to the crystal bend by an angle of about 48 μrad, 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.