Optimum channel combinations for multichannel airborne gamma-ray spectrometry

Abstract

A new method for determining the optimum channel combinations for reducing the number of channels of data for multichannel airborne gamma-ray spectrometry is developed. The concept of 'generalised' channels, which are the summation of one or more 12 keV data channels that are not necessarily contiguous in the spectrum is introduced. The method uses a simulated annealing minimisation technique to find the best generalised channels such that the sum of the fractional errors for each of the 3 radioelements is minimised. All methods of summing channels lead to an increase in the fractional errors of the radioelements. But the new method is an improvement on existing methods, with the greatest improvement occurring as the number of generalised channels is decreased. A simple method of determining optimum window boundaries for conventional 3-channel airborne gamma-ray spectrometry is also demonstrated. Equivalent thorium fractional concentration errors can be reduced by broadening the conventional 208TI window.