A scintillating fiber detector for π0 identification

Abstract It has been known for several years that electromagnetic calorimetry with scintillating plastic fibers gives good results at high energy (ref. [1] H. Blumenfeld et al., Nucl. Instr. and Meth. 225 (1984) 518; ref. [2] H. Burmeister et al., Nucl. Instr. and Meth. 225 (1984) 530). A measurement done with 40 MeV electrons [2] convinced us that this technique can be applied for the identification of π 0 particles produced in the capture of negative pions by protons. A prototype detector has been built, calibrated and used in coincidence with a NaI detector to identify the decay of neutral pions produced by stopping a 200 MeV/ cπ − beam in a CH 2 target. Results are discussed and compared with a Monte Carlo simulation. Finally, a full-scale detector has been built and successfully used in a measurement of the X-ray yield in pionic hydrogen.