Physics and Engineering of Radiation Detection

464 Chapter 8. Signal Processing

Spectroscopic Applications Timing Applications

Detector

Preamplifier

Pulse Shaping

Amplifier Amplifier

Timing

(SCA, MCA)

Analyzer

Pulse Height Discriminator &

Time−to−Amplitude

Converter

Figure 8.0.1: Typical analog signal processing steps involved

in timing and spectroscopic applications.

8.1 Preamplification

The analog signal pulse produced as a result of passage of radiation through a
detector usually has very narrow width and amplitude and therefore can not be
directly digitized or even counted. Unless the detector signal has enough strength
(i.e., the height of the pulse is large enough), it must first be preamplified before
transporting it to other processing units. A preamplifier is a simple but efficient
amplifier that is directly connected to the detector output.
Different kinds of preamplifiers can be constructed to suit the specific detector
and processing requirements. Several parameters are considered when designing a
preamplification circuitry, most of which belong to competing requirements. Hence
the design process is actually optimization of some of these parameters to suit the
specific needs. Some of the important design specifications of any preamplier are

signal to noise ratio (S/N),

range of input signal.