Leading edge timing compensation for accurate drift-time measurements in the case of resistive anode wire

摘要

A medium-size cylindrical drift chamber with the z-coordinate determination by the charge division has been constructed and tested using cosmic ray muons Since resistive wires (2.37 kΩ) are used, the signal pulse heights at both ends of the anode wires depend on the positions of the particle tracks. As we used leading-edge discriminators and TDCs to measure the drift time, we have made a leading-edge compensation by the formula, Δt=A/{the square root of}Q. Here Q is the integrated charge, and A is a constant determined experimentally. As the result of the timing corrections, we could improve the position resolution and also the drift-times for all wires were correctly treated, irrespective of large fluctuations of primary ionizations in each cell of the drift chamber.