Question

what is the energy calibration and efficiency calibration and why they are needed before measurement? (From gamma-ray spectroscopy analysis by HPGe detector)

Answer 1

Calibration is the process of evaluating and maintaining the instrument precision and accuracy to provide a result for a sample with in an acceptable range.

Gamma – ray spectroscopy is one of the powerful techniques used to identify the unknown radioactive samples that emit gamma rays. The main advantage of this technique is that it is a non – destructive technique (that means samples can be get back after analysis)

The instrument should be calibrated to check its precision and accuracy with the samples of known values to establish a relationship between the values of the standards and the corresponding measurements. This process teaches instrument to produce more accurate values when samples of unknown values are tested. The γ-ray spectrometer also should calibrate in two ways which includes the energy calibration, and the detection efficiency calibration.

The object of energy calibration is to derive a relationship between peak position in the spectrum and the corresponding γ-ray energy. Energy calibration will be done by measuring the spectrum of a source emitting γ-rays of precisely known energy and comparing the measured peak position with energy. The efficiency calibration is to calculate the relationship between number of counts and disintegration rate. This is the parameter of most significance in practical γ-ray spectrometry.