Reconstruction of double hits from drift chamber FADC pulses

Abstract A method is proposed to recognize and resolve double-hit structures in 100 MHz FADC pulses using data taken with prototypes of the cylindrical outer z chamber of the HERA detector H1. With 90% efficiency double hits can be resolved down to distances of about 2.5 mm. The peak position of the second pulse can be reconstructed by subtracting a reference pulse from the signal which is derived from the data themselves. The resolution for perpendicular track crossing is about 250 μm. The method is fast and can be extended to multiple hits ( n > 2).