Energy dependence of isomeric ratios for alpha-particle-induced reactions on natural platinum up to 50 MeV studied by simultaneous decay curve analysis

The isomeric ratios and cross sections were measured up to 50 MeV for production of $^{198m,g}$Au, $^{197m,g}$Hg, $^{195m,g}$Hg and other Hg, Au and Pt radionuclides in irradiation of natural platinum by alpha-particles using the stacked foil activation technique and offline gamma-ray spectrometry. The simultaneous decay curve analysis was applied to the emission rates of more than 40 gamma lines to directly derive the independent cross sections of all products without determining the cumulative cross sections. The measured cross sections and isomeric ratios were compared with those compiled in the EXFOR library and simulated by TALYS-2.0. We found that the $^{nat}$Pt($α$,x)198g+mAu, $^{197g+m}$Hg and $^{195g+m}$Hg cross sections are fairly reproduced by the simulation, while the simulation result requires adjustment of the spin cutoff parameter for better reproduction of the isomeric ratios.