Gamma ray full spectral analysis method optimization of an ill-conditioned problem AiYun Sun, WenBao Jia, DaQian Hei, Can Cheng and JiaTong Li Eur. Phys. J. Plus, 137 8 (2022) 929 Published online: 16 August 2022 DOI: 10.1140/epjp/s13360-022-03103-w