  178m2-Hf is an extremely interesting isomeric state due to its potential
energy capacity level. One possible way to obtain it is by irradiation of a
nat-Ta sample with a high-current proton accelerator. Up to now, there was no
information in the international experimental nuclear data base (EXFOR) for
this reaction. Irradiations of nat-Ta samples performed for other purposes
provide an opportunity to address this question. This paper presents the
172m2-Hf independent production cross-sections determined by gamma-ray
spectrometry. The nat-Ta(p,x)172m2-Hf excitation function is studied in the
20-3500 MeV energy range. Comparisons with results by several nuclear models
(ISABEL, Bertini, INCL4.5+ABLA07, PHITS, CASCADE07, and CEM03.02) used as
event-generators in modern transport codes are also reported. However, since
such models are generally not able to separately predict ground and isomeric
states of reaction products, only 178-Hf independent and cumulative
cross-section data are compared.
