G. Charpak et al., EXPERIMENTAL-STUDY OF AN IMPACT-PARAMETER OPTICAL DISCRIMINATOR, Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 332(1-2), 1993, pp. 91-99
An optical discriminator, sensitive to the impact parameter has been t
ested in a particle beam. The device is based on the detection of Cher
enkov light produced and trapped in a thin spherical crystal shell vie
wed by a fast photodetector. The detector is only sensitive to charged
particles with a nonzero impact parameter relative to the centre of t
he crystal sphere. A prototype using a LiF crystal has been tested and
the experimental results are in agreement with expectations. We outli
ne the foreseen developments in order to use such a detector for a fas
t selection of B events in fixed-target experiments at proton accelera
tors. We also discuss the use of the detector as presently conceived f
or the fast selection of strange particles.