Some Other Topics Related to PIXE Analysis

The background fit BKGD x,Py) and the collection of peak fits PEAKj(x, Pj, CT, p.) are summed at each channel x to yield the total 

The least square fitting can be performed by the method of Marquardt which combines a gradient-type search for minimum with linearization of the fitting function. 

The exit from the iterative fitting loop is made automatic or manual when x is less than 10 . For those elements which are not detected, the program can also provide the limit of detection (ppm) calculated as 2 y/B/S, where B is the integrated background (i.e., nonpeak) count in a region centered at the computed centroid and having a width of one FWHM while S is the number of counts of elemental X-rays in the line. 

From the estimates of the amplitudes Hj and width a of the fitted peaks, the peak areas are computed as  

11 Some Other Topics Related to PIXE Analysis 

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