Chapter 6
Scintillation Counter
6.1 Introduction
From Chap. 5, we realized that although ionization counters are handy instruments
to measure activity of radioactive samples, but it cannot be very useful for counting
γ -rays or low energy β-particles or α-particles, because these types of radiations are
incapable to either generate ion-pairs within the ionization chamber or penetrate the
window of the counter to produce ion-pairs. Therefore, there is a need to develop
counters to measure the activities of these types of radiations also. This is achieved
by using a scintillation counter which is discussed in detail in this chapter.
6.2 Scintillation Counter
A scintillation counting system is a combination of electronic devices, by which
flashes of visible light produced by the interaction of radiation with a fluorescent
material are converted to voltage pulses of size which can be recorded by a scaler
unit. The visible photons liberate electrons at the photocathode of a photomultiplier
tube, which are multiplied by a series of dynodes, each held at potential more positive than the previous one. The multiplied electrons, thus, form a voltage pulse at the
anode tube. The negative pulses (like the negative anode pulses generated in ionization counter) are amplified and discriminated, and are finally counted either by an
electronic scaler unit or scanned and converted to a spectrum. A schematic diagram
of the scintillation counter is shown in Fig. 6.1.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
M. Sharon and M. Sharon, Nuclear Chemistry,
https://doi.org/10.1007/978-3-030-62018-9_6
95
Scintillation Counter
6.1 Introduction
From Chap. 5, we realized that although ionization counters are handy instruments
to measure activity of radioactive samples, but it cannot be very useful for counting
γ -rays or low energy β-particles or α-particles, because these types of radiations are
incapable to either generate ion-pairs within the ionization chamber or penetrate the
window of the counter to produce ion-pairs. Therefore, there is a need to develop
counters to measure the activities of these types of radiations also. This is achieved
by using a scintillation counter which is discussed in detail in this chapter.
6.2 Scintillation Counter
A scintillation counting system is a combination of electronic devices, by which
flashes of visible light produced by the interaction of radiation with a fluorescent
material are converted to voltage pulses of size which can be recorded by a scaler
unit. The visible photons liberate electrons at the photocathode of a photomultiplier
tube, which are multiplied by a series of dynodes, each held at potential more positive than the previous one. The multiplied electrons, thus, form a voltage pulse at the
anode tube. The negative pulses (like the negative anode pulses generated in ionization counter) are amplified and discriminated, and are finally counted either by an
electronic scaler unit or scanned and converted to a spectrum. A schematic diagram
of the scintillation counter is shown in Fig. 6.1.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
M. Sharon and M. Sharon, Nuclear Chemistry,
https://doi.org/10.1007/978-3-030-62018-9_6
95