Introduction
VF1807090083 EN revision 12
The total number of counts per preset time interval.
Background that simulates the ambient background for which the instrument is specified.
The decision making level and the detection limit are usually determined for a typical value
of the reference background of 100 nGy/h, unless stated differently.
Relative error of an instrument that is related to the given quantity when exposed to the
specific reference radiation under the specified reference conditions. It is expressed in
[%].
Reciprocal value of the instrument response. The units are usually [Bq/cps], [(Bq∙cm
-
2
)/cps].
Ratio of the corrected count rate of the measuring instrument to the measured quantity
(activity, surface activity, dose rate, etc.). The unit of response to activity is usually
[cps/Bq], to surface activity [cps/(Bq∙cm
-2
)] and to dose rate [cps/(Sv/h)],[cps/(Gy/h)].
Sensitive area of the
detector
Detector area, which is defined by the producer, with a response to small area source
(CRM) higher than 50 per cent of the maximum response. The unit is usually
[cm
2
].
Quotient of the activity of the radionuclide present on the surface and area for this
surface. The unit is usually [Bq∙cm
-2
].
Radioactive surface contamination.
The number of particles of a certain type emitted from the source surface or its active part
per time unit. The unit is [1/s].
ZnS(Ag) is the inorganic salt of hydrosulphuric acid and zinc hydroxide activated by silver
(Ag). It is a white and crystalline substance which is not soluble in water, similarly as the
majority of sulphides. A charged alpha particle imparts its energy to the scintillation
centres that contain the atoms of silver. This leads to ZnS luminescence and photon
emission with a maximum wavelength of 450 nm.
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