Nuclear-Detectors-notes

Chapter5: THe GENERAL Chracterisitcs of any detector:

Introduction

• The main characteristics of any detector is that the total (or partial) energy of the radiation is absorbed by the detector mass which then is converted in other form which is more accessible to the human perception.
• The charged radiation will ionise or excite the atomic electrons.
• Neutral radiation have to go for some sort of radiation producing charged particles, which in turn ionize and excite the detector atoms.
• The electrical detectors are modernily used as it will convert the signal into electrical impulses which later can easily be analyzed.

5.1 Sensitivity

(Detecting the radiation)

• Sensitivity: The production of usable signal for given type of radiation and energy

The sensitivity of the detector depends on the following characteristics:

1. Cross section and detector mass: This determines the probability of the ionization process.

2. Detector noise: This determine the certain minimum that can only be detected because of the inherite noise present in the electronics of the detector.

3. Material covering the entrance window: The absorbing capacity of the material sets the minimum energy threeshold.

5.2 Detector Response

Mapping the linear (or non-linear) relation between output signal and energy of the radiation

Construction of the output signal:

1. The ionized electrons in the form of current (vs time) is integrated to get the amount of charge which is linearly proportional to the amount of ionizaion.

2. Assuming if the pulse shape is same for all the events, we can assume that the height of the pulse width is only important and the integral is only proportional to the pulse height. And

3. The relation between the radiation energy and the pulse height (the total charge) can be referred as the response of the detector.

4. Ideally, this relation is supposed to be linear…

5.3 Energy Resolution: The Fano Factor