Response of a scintillating fibre detector to proton and pion beams at GSI

The HERMES collaboration at DESY will install a new recoil detector surrounding its target region for the envisaged final two years of the HERA II running period aiming at detecting recoiling nucleons from hard exclusive scattering [1, 2]. Protons and Pions with momenta p > 250 MeV/c will be detected and identified by a two–barrel scintillating fibre tracker (SFT). It consists of two barrels made from 1 mm Kuraray SCSF-78 scintillating fibres each. A stereo angle of 10◦ between each two adjacent layers of each barrel allow space point reconstruction. The diameters of the barrels are 220 mm and 370 mm, respectively. Beam tests of prototype modules for the SFT using particles in the relevant momentum range will be reported in this paper. Their applicability to the envisaged experiment will be evaluated.