Signal Processing for Radiation Detectors

3Preamplifiers

In Chapter 1, we discussed that an interaction of ionizing radiation with the sensitive volume of a detector in the end always leads to a short current pulse. In most of the cases, the pulse produced in the detector is read out with a preamplifier, which constitutes a critical part of a measurement system as its choice affects the quality of information that can be extracted from the pulses. In this chapter, we review the basics of different types of preamplifiers that are commonly used with various types of radiation detectors. The requirements for the high voltage bias supply of different detectors are also discussed.

3.1 Background

The primary function of a preamplifier is to extract the output signal of the detector. This act must be performed with minimum degradation of the quality of information that is intended to be measured. Such information can be in the amplitude and/or the shape of the pulse signals. The information carried by the amplitude of the pulses is generally used for energy spectroscopy applications, while the information in the time profile of the pulses are generally required for timing and pulse‐shape discrimination applications. The quality of information in the signals can be degraded, in the first place, by the effect of electronic noise, though there are some exceptions such as photomultiplier and GM tubes in which, because of their built‐in signal amplification mechanism, sufficiently large pulses are produced, and therefore the effect ...