For reaction involving particle emissions, often the final, ground state or excited, level ofthe residual nucleus is not provided in the evaluated data files. The FLUKA implementation tries to guess as best as possible the final excitation on the basis of the inclusive spectra of the emitted particles and physics consideration. The following de-excitation is performed using the standard FLUKA de-excitation models, which heavily rely on experimental data when within the range of known levels. For (n,gamma) reactions in the thermal region, the capture photons emission schemes are as much as possible based on experimental data of primary de-excitation from the capture level as available in the ENSDF database. For many light and medium isotopes the available data are more or less complete. For medium to heavy nuclei, the available data, when present, often cover only a fraction of the possible schemes. The missing informations are generated as usual by the FLUKA de-excitation models. Therefore the agreement with experimental secondary lines can be very good when primary ones are almost completely known, questionable otherwise. It should be noted that even evaluated data files often contain model calculated capture gamma spectra, in some cases not even in agreement with experimentally known primary lines. For capture reactions in the resonance region, the same de-excitation schemes of the thermal range are applied. This is obviously not correct since the spin and parity of the given resonance could be different from those of thermal capture, however the experimental data about gamma spectra in the resonance region are very scarce. As a consequence of all the above consideration, production of a specific isomer can be very accurate in some cases, eg for (n,n') specifically ending up on that level, or much less accurate in others. If accurate predictions os isomers are of importance, it is better to rely on the group-wise cross sections which contain their (uncorrelated) production branchings as derived from available evaluated activation files.
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