HIGH-RESOLUTION Y-AXIS READOUT FOR DELAY-LINE MICROCHANNEL ANODES

We have devised a method to obtain a high-resolution Y-axis event position determination from microchannel plate delay-line detectors. The method is based on the double-delay-line wedge-wedge charge partition principle of Lampton et al. [M. Lampton, 0. H. W. Siegmund, and R. Raffanti, IEEE Trans. Nucl. Sci. 37, 1548 (1990)], where the X axis is read out by a pair of side-by-side delay lines and the Y-axis coordinate is determined by comparing the charges on the two parallel delay lines. However, our new method abandons the common field return path of the two delay lines, and splits them into two adjacent but independent transformer coupled timing circuits having no common ground connection except via the charge-measurement amplifiers. Thus we eliminate the large electrostatic capacitance of the delay lines from the input of the charge-measuring system. Due to the very low output return capacitance of the split delay lines, the Y-axis noise performance is improved enormously. Over its limited working field, the spatial resolution in the Y coordinate can easily equal the resolution provided in the X coordinate by the delay line. Applications to extreme and far ultraviolet photon-counting spectroscopy are envisioned.