Cut Gaussian

Hi, I have data that unfortunately was cut on one side by the detector (see picture attached.

I would like to reconstruct this by mirroring the left-hand side to replace the right.

I can think of one way (a macro that bins the data, loops over the bins to fill an array, then writes a new histogram with the descending left side values on the right), but is there a better solution?

Cheers, Ben.

just fit to a gaussian with range from 0 to the point of suspected cutoff.

Use this gaussian function to set bins in the cut-off right side.
Although I am not sure why …