Abstract: This paper investigates the alpha energy spectrum of ²⁴¹Am and analyzes its generation process. Based on the analysis, detector response function is derived, and a detector response function model based on the convolution of exponential and Gaussian functions is established for the alpha energy spectrum of ²⁴¹Am. The model parameters are obtained using the weighted nonlinear least squares method, and the goodness of fit is evaluated using the Reχ². The model is then used to reconstruct the alpha energy spectrum of ²⁴¹Am obtained from Geant4 simulation. The impact of source-to-detector distance on fitting performance is investigated. This study could provide theoretical guidance for the development of an alpha spectrometer and algorithm design based on the PIPS detector.

Key words: alpha energy spectrum, detector response function, weighted nonlinear least squares method, Geant4 simulation