Look for a specific peak in a histogram

Dear Exparts,
I want to build a gated 1D gamma spectrum which will be in coincidence with a specific gamma energy. Can you please help me how to do it? I guess I need to build a 1D histogram at first, search for the peak of my interest and then build another histogram which will be in coincidence with that peak. I know there is a peak search option in the TSpectrum, but I do not know how to search for a peak at a particular energy. I will highly appreciate any suggestion on how to proceed.

Thank you.

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I think you need to discuss it with your supervisor and / or your colleagues who know how your data look like and how to deal with them.

Thanks, I figured it out!