The ¹⁹⁷Au(p, x)^{194, 196}Au reactions are promising candidate reactions for proton beam monitoring. The two channels share the same target foil, allowing cross-checked beam monitoring with a wide energy coverage. The two product nuclei have half-lives on the order of days, which matches most proton irradiation schedules. Their decay data are reliable, with uncertainties below 5% in both the half-lives and the main γ-ray branching ratios. However, inconsistencies are present among the published experimental data for these reactions, and significant discrepancies are observed between the evaluated data libraries values and experimental data.
In this work, the experimental data below 60 MeV were collected and analyzed from an experimental nuclear physics standpoint. The data include nine datasets for ¹⁹⁷Au(p, x)¹⁹⁶Au and six datasets for ¹⁹⁷Au(p, x)¹⁹⁴Au. The analysis followed three steps. First, the decay parameters (half-life and γ branching ratio I_γ) used in each original measurement were compared with the current evaluated values from NuDat 3.0, and a correction factor was applied where a clear bias was found. Second, for relative measurements, the reference cross sections used in the original work were compared with the current IAEA recommendations, and an energy-point-by-energy-point correction was applied. Third, datasets with identifiable systematic problems were excluded: for example, one experimental group used half-life values differing by nearly 10% from those given in NuDat 3.0 when calculating cross sections; measurements of ^196m2Au activity via γ-ray spectroscopy sometimes utilized overlapping characteristic peaks, which led to inaccurate activity determination; and some experiments employed stacked-foil targets with incorrect energy calculations.
The processed experimental data are in good agreement within the uncertainties. The corrected data were fitted using the SPCC spline fitting program developed at the China Nuclear Data Center. Recommended excitation functions were obtained for ¹⁹⁷Au(p, x)¹⁹⁶Au, ¹⁹⁷Au(p, x)^196(g+m1)Au, ¹⁹⁷Au(p, x)^196m2Au, and ¹⁹⁷Au(p, x)¹⁹⁴Au below 60 MeV. Compared with JENDL-5.0 and TENDL-2025, the existing evaluations are systematically low at low energies for ¹⁹⁶Au, whereas JENDL-5.0, TENDL-2025, and the IAEA Padé fit of Tárkányi et al. are systematically high above 30 MeV for ¹⁹⁶Au and above 45 MeV for ¹⁹⁴Au.
Integral yield curves over the studied energy range were derived and compared with experimentally measured yields at specific energy points. Similarly, experimental thick-target yields were collected and analyzed from an experimental nuclear physics standpoint. One experimental group reported thick-target yields for several common reactions, including ^natCu(p, x)^{62, 65}Zn, ^natNi(p, x)⁵⁷Ni, ^natTi(p, x)⁴⁸V and ^natMo(p, x)^96m+gTc, whose results deviated from IAEA recommended values by a factor of about two; thus, these data were excluded from comparison in this work. For some experimental data reported as differential thick-target yields, this work utilized SRIM-calculated stopping power data to derive reaction cross sections from yields. These cross sections were notably higher than all existing experimental data above 30 MeV, indicating a systematic overestimation that led to elevated thick-target yield values. After rejecting these significantly deviated datasets, the obtained results were in good agreement with the experimental data.
The recommended data obtained by fitting showed noticeably better agreement with the corrected cross-section data than existing evaluated results. The experimental data within the 30–60 MeV range fall into two distinct groups, and the evaluated libraries also disagree with each other in this range. This study therefore provides valuable data support for proton beam monitoring and contributes to the extension of the database. These results should be further checked by measurements directly in the future because the available experimental data are very scarce. Additionally, the cross section ratios of ¹⁹⁷Au(p, x)^194,196Au exhibit significant energy dependence over a wide proton energy range, indicating that these reaction cross sections can be employed for proton energy determination, which may serve as a direction for subsequent research.