Production of $${^{180\textrm{m}}}$$Hf in photoproton reaction $${^{181}}$$Ta$$(\gamma ,p)$$ at energy $$E_{\mathrm{\gamma max}} = 35$$–95 MeV

Abstract

AbstractThe production of the $$^{180\textrm{m}}\textrm{Hf}$$ 180 m Hf nuclei in the photoproton reaction $${^{181}\textrm{Ta}}(\gamma ,p)$$ 181 Ta ( γ , p ) was studied at end-point bremsstrahlung energies $$E_{\mathrm{\gamma max}}=35$$ E γ max = 35 –95 MeV. The experiment was performed at the electron linear accelerator LUE-40 NSC KIPT with the use of the $$\gamma $$ γ activation and off-line $$\gamma $$ γ -ray spectroscopy. The experimental values of the bremsstrahlung flux-averaged cross-sections $$\langle {\sigma (E_{\mathrm{\gamma max}})}\rangle _{\textrm{m}}$$ ⟨ σ ( E γ max ) ⟩ m for the $${^{181}\textrm{Ta}}(\gamma ,p)^{180\textrm{m}}\textrm{Hf}$$ 181 Ta ( γ , p ) 180 m Hf reaction were determined, and at $$E_{\mathrm{\gamma max}} > 55$$ E γ max > 55  MeV obtained for the first time. The measured values, as well as the literature data, significantly (by more that an order of magnitude) exceed the theoretical flux-averaged cross-sections $$\langle {\sigma (E_{\mathrm{\gamma max}})}\rangle _{\textrm{th}}$$ ⟨ σ ( E γ max ) ⟩ th . The $$\langle {\sigma (E_{\mathrm{\gamma max}})}\rangle _{\textrm{th}}$$ ⟨ σ ( E γ max ) ⟩ th values were calculated using the cross-section $$\sigma (E)$$ σ ( E ) computed with the TALYS1.95 code for six different level density models. A comparative analysis of the calculated total cross-sections from the TALYS computation for the reactions $${^{181}\textrm{Ta}}(\gamma ,p)^{180}\textrm{Hf}$$ 181 Ta ( γ , p ) 180 Hf and $${^{181}\textrm{Ta}}(\gamma ,n)^{180}\textrm{Ta}$$ 181 Ta ( γ , n ) 180 Ta was performed. It was shown that the photoproton $$(\gamma ,p)$$ ( γ , p ) to photoneutron $$(\gamma ,n)$$ ( γ , n ) strength ratio is consistent with the estimates based on the isospin selection rules and the value from the $$(e,e'p)$$ ( e , e ′ p ) experiment.