TABLE OF CONTENTS Errors of measurement are of two types, random and systematic. For a given set of measurement conditions a source of random error is variable in both magnitude and sign, whereas a source of systematic error has a constant relative magnitude and is always of the same sign.
The accuracy is affected by both systematic and random uncertainties.
Accuracy is related to the closeness of a measurement, within certain limits, with the true value of the quantity under measurement. For instance, the accuracy of dose determination by TLD is given by the difference between the measured value of the dose (TL reading) and the true dose given to the dosimeter.
A method of combining systematic and random uncertainties has been suggested in a BCS document: both systematic and random errors are combined by quadratic addition but the result for systematic errors is multiplied by 1.13. This factor is necessary to ensure a minimum confidence level of 95%.
British Calibration Society, BCS Draft Document 3004
It is the energy, E, expressed in eV, assigned to a metastable state or level within the forbidden band gap between the conduction band (CB) and the valence band (VB) of a crystal. This energy is also called trap depth. The metastable level can be an electron trap, near to the CB, or a hole trap, near the VB, or a luminescence centre, more or less in the middle of the band gap. The...
