Page 552 - Instrumentation Reference Book 3E

534 Nuclear instrumentation technology

Nal(TI) coincidence detector

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4 - - -- - - - - - - - - - - 7.65 cm diameter - - - - - - - - - -- - -
Gas out

Anode wire

I
Perspex HV II
f Gasin

Na I(TI) coincidence detector

Figure 22.8 Typicaldesignof 4xcounter

worldwide as a sub-standard to the fi-ee air ioniza- resolution compared with a NaI (Tl) detector can
tion chamber for measuring dose and dose rates be seen in Figure 22.10, which shows how the
for human beings. solid-state detector can resolve the 1.17 and
1.33 MeV lines from 6oCo with the corresponding
NaI (Tl) scintillation detector result superimposed.
Solid-state detect0r.s The impact of solid-state For energy resolution the solid-state detector
detectors on the measurement of gamma-rays provides a factor of 10 improvement on the
has been dramatic; the improvement in energy scintillation counter. However, there are a num-