Tables for
Volume H
Powder diffraction
Edited by C. J. Gilmore, J. A. Kaduk and H. Schenk

International Tables for Crystallography (2018). Vol. H, ch. 2.1, pp. 46-47

Section Scintillation counters

A. Kerna*

aBruker AXS, Östliche Rheinbrückenstrasse 49, Karlsruhe 76187, Germany
Correspondence e-mail: Scintillation counters

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Scintillation counters are constructed from a scintillator crystal optically coupled to a photomultiplier tube. The crystal is typically made of sodium iodide (NaI) doped with about 1% thallium, frequently denoted as NaI(Tl). When irradiated by X-ray radiation, blue light (∼415 nm) is emitted and converted to electrons in a photomultiplier and amplified; the resulting pulses are registered as photon counts.

The height of the outgoing pulses is proportional to the energy of the incoming X-ray photons. This permits the use of pulse-height selection but only allows for poor energy resolution. The relatively high count rate and a moderate noise level result in a moderate dynamic range. These characteristics are the reason for the formerly wide-ranging acceptance of the scintillation counter as the detector of choice. An important disadvantage these days is the limitation to 0D detection.

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