Physics and Engineering of Radiation Detection

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Chapter 13

Data Acquisition Systems

Data acquisition is an extremely important part of any radiation detection system.

The development of highly sensitive and fast detectors has stretched the require-

ments on data acquisition systems so much that it has lead to advancements in the

technology of high end electronic devices. A typical modern data acquisition system

is composed of analog and digital processing modules, computer interface, computer,

software, and storage device. There are essentially three ways in which a complete

data acquisition system can be designed. The first one is to use the so called modular

instruments, which consist of pre-built modules. These modules are designed such

that they can be joined together to form a complete system. This approach was very

popular in early days of electric detectors due to ease in design and implementation.

Their main downsides are the use of the modules as black boxes and be restricted

to the vendor’s specifications. Even with these disadvantages, such systems are still

popular in small scale systems where building a complete application specific system

is cost prohibitive. Another approach is to design a completely application specific

system. This requires large investment of capital, manpower, and time but is highly

advantageous for large scale systems. The third approach is to build a hybrid sys-

tem, that is, a system based on modular instruments and some application specific

devices. This chapter to reviews of modular and application specific devices.

We will start this chapter with discussions on complete data acquisition systems

without going into the details of their individual building blocks. Later on we will

look at the standards of modular instruments. The last part of the chapter is devoted

to the PC based data acquisition systems.

13.1DataAcquisitionChain

In this section we will look at the broader picture of how specific tasks related to

radiation measurements can be performed. Design of a data acquisition system,

to a large extent, depends on the application. For example, a system designed for

slow pulse counting can not handle high data rates. Therefore it is instructive to

give examples of systems for specific applications that are commonly encountered in

radiation measurements.

13.1.APulseCounting..........................

Pulse counting is perhaps the most widely used operation mode of radiation detec-

tors. The basic idea is to count the number ofgoodpulses generated by individual