Effects of Secondary Electron Emission on Charge Pulses from a Z-Stack Microchnnel Plate Photon Counting Detector with a Crossed Delay Line Anode Readout

A study of the effects of secondary electron emission on charge pulses from a microchannel plate (MCPs) photon counting detector with crossed delay line (CDL) anode readout is presented. The detector is a two-dimensional photon counting detector with fast count rate and good spatial resolution being developed at Los Alamos National Laboratory. The CDL anode is constructed of two orthogonal planar pairs of helically wound wires on inner and outer ceramic sides attached to a copper ground plane. The electron cloud event from the MCPs interacts with the wires generating a signal pulse. The electrons that strike the wire with sufficient energy generate secondary electrons. A model is presented for the charge pulses from the CDL anode incorporating the effects of secondary electron emission. An empirical test of the model is conducted with two different wire materials using a demountable MCP/CDL detector. Charge pulses are measured and the results are compared to the model. The results show that the charge pulses from the CDL anode are material dependent and exhibit the general behavior predicted by the model. Secondary electron emission is an integral part of the CDL anode charge pulses and must be considered in further developments of the CDL anode readout.