Second Coordinate Readout in Drift Chambers by Charge Division

The drift time measurement and the charge division can be performed simultaneously on the same electrode (resistive anode) without affecting the accuracy of either measurement. It is shown that for the shortest measurement time there is an optimum value for the anode wire resistance. The signal requirement for a position uncertainty ¿ ¿ 0.5% of the anode wire length is only 2.7 x 106 electron charges. The drift chamber can be operated in the linear mode and with negligible space charge effects, so that it can also be used for ¿E/¿X measurements. A simple preamplifier optimized for both the time and charge measurements using a monolithic transistor array is described.