INSTRUMENTATION FOR TXRF AND GI-XRF - Total-Reflection X-Ray Fluorescence Analysis and Related Methods - page 194

Figure3.29. Total peak width or line width as a measure of the spectral resolution dependent on
the photon energy or peak position in a double logarithmic plot. The peak width was calculated for
four different proportional detectors: a NaI(Tl) scintillation detector, an Ar gas-filled detector, a Si
(Li), and an SDD used for EDS. They are compared to the peak width of a WDS with Bragg
crystals: LiF(422); LiF(200); PET; TlHP; and Mo/B 4 C, each with a collimator of 0.15 ° divergence.

TABLE3.10.InfluenceoftheCrystalSizeofSi(Li)andHPGe
DetectorsontheSpectralResolution Δ E oftheMn-K α Peak
Size of Detector Crystal Spectral Resolution

Noise Si(Li) HPGe

Frontal Area (mm 2 ) Δ E noise (eV) Δ E (eV) Δ E (eV)

Diameter (mm)

3.6 10 50 128 115

6.2 30 62 133 120

8.0 50 75 140 127

10.1 80 95 151 140

Source : From Ref. [2], reproduced with permission. Copyright1996, John Wiley and Sons.

3.8.2.3Input-OutputYield

The number of pulses produced by the detector crystal within a certain time
interval is called the inputrate . The number of pulses being processed by the
electronic chain and indicated by the MCA is defined as the outputrate .
The input and output rates differ from one another due to the dead time effect
of the electronic system.