The General Method of Unfolding

This section discusses methods of unfolding, assuming that an energy spectrum is measured with a multichannel analyzer or any other device that divides the measured spectrum into energy bins. As stated at the beginning of Sec. 11.5, unfolding means to solve the Fredholm-type integral equation 

This case is not encountered in practice because there is no detector with such a response function it indicates only that with perfect energy resolution there is no need for unfolding. In general, the more the detector response resembles a 

8-function, the more the measured spectrum looks like the source spectrum. 

A second type of response that gives an analytic solution, in principle, is a step function (Fig 11.10). Let 

The lower limit of the integral has been set equal to E because if the response function is that given by Eq. 11.41, no source particles with energy E E can contribute to M(E). Upon differentiation,11.42 gives 

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