<title>Effects of charge cloud size and digitization on the SPAN anode</title>

Abstract

Microchannel plate (MCP) detectors are often used with charge division anode readouts, such as the SPAN anode, to provide high position resolution. This paper discusses the effect on image quality, of digitization (causing fixed patterning), electronic noise, pulse height distribution (PHD) and charge cloud size. The discussion is supported by experimental data obtained from a one dimensional SPAN anode, developed for the SOHO Coronal Diagnostic Spectrometer (CDS) Grazing Incidence Spectrometer (GIS). Results from a computer model of this detector, and from a charge cloud simulation model, are also included. The SPAN anode normally has three sinusoidal electrodes with phase differences of 120 degree(s)C. An alternative configuration is to use a phase difference of 90 degree(s)C. This paper compares the advantages and disadvantages of these arrangements.