Signal Processing for Radiation Detectors

7Position Sensing

The determination of spatial information on the location of radiation interactions with a detector is required for a variety of applications from medical imaging to nuclear physics research. The objective of this chapter is to discuss in some details the principles and the performance of the commonly used techniques with position‐sensitive detectors. Our discussion includes position sensing with gaseous, semiconductor, and scintillation detectors.

7.1 Position Readout Concepts

7.1.1 Basic Definitions

A position‐sensitive detector is a detector whose output signals carry information on the location of radiation interaction with the detector. The information can be provided in one, two, or three dimensions, and the corresponding detectors are called, respectively, one, two, and three‐dimensional position sensitive. For indirectly ionizing particles such as gamma‐rays and neutrons, the spatial information of interest is the interaction point with the detector while for charged particles, for which interaction takes place along the particle’s track in the detector, the impact point of the particle with the detector is generally required as spatial information. A basic property of a position‐sensitive detector is how well the detector is able to distinguish between two closely spaced interactions with the detector. This property is quantified with spatial resolution and is a critical criterion used to characterize the usefulness of a detector for a particular application. ...