Photoneutron reactions on $^{\text{93}}$Nb at $E_{\gamma \text{max}}$=33-93 MeV

TL;DR

This study measured bremsstrahlung flux-averaged cross sections and isomeric ratios for photoneutron reactions on $^{93}$Nb at energies 33-93 MeV, comparing experimental data with TALYS and GEANT4 calculations, revealing good agreement for some reactions and discrepancies for others.

Contribution

First-time measurement of average cross sections for ($ ext{γ}$,2n), ($ ext{γ}$,4n), and isomeric ratios for ($ ext{γ}$,5n) reactions on $^{93}$Nb, with comparison to theoretical models.

Findings

Good agreement between experiment and theory for ($ ext{γ}$,2n) and ($ ext{γ}$,4n) reactions.

Discrepancies observed in ($ ext{γ}$,n), ($ ext{γ}$,3n), and ($ ext{γ}$,5n) reactions.

Experimental data for ($ ext{γ}$,n), ($ ext{γ}$,3n), and ($ ext{γ}$,4n) reactions agree with literature.

Abstract

The bremsstrahlung flux-averaged cross sections for the photoneutron reactions $^{\text{93}}$Nb($\gamma $,xn;x=1-5)$^{\text{(93-x)m,g}}$Nb were measured in the range of boundary energies of bremsstrahlung $\gamma $-quanta $E_{\gamma \text{max}}$=33-93 MeV with a step $\Delta E_{\gamma \text{max}}\approx $ 2 MeV. The isomeric ratios of the average cross-sections of the products of the reactions $^{\text{93}}$Nb ($\gamma $ ,4n)$^{\text{89m,g}}$Nb and $^{\text{93}}$Nb($\gamma $,5n)$^{\text{88m,g}}$ Nb were determined in the energy ranges $E_{\gamma \text{max}}$ = 50-93 and 70-93 MeV, respectively. The experiments were carried out on the beam of the linear electron accelerator LU-40 of the Science and Research Establishment (SRE) "Accelerator" at National Science Center Kharkov Institute of Physics and Technology (NSC KIPT) using the method of induced activity. Calculations of the cross sections, average cross sections, and isomeric ratios of the reaction products were performed using the TALYS 1.9 code with default parameters and the GEANT4 code. The tendency of a more successful description of the average cross sections of photoneutron reactions with the formation of final odd-even Nb nuclei than odd-odd Nb nuclei is revealed. The experimental average cross sections for the reactions ($\gamma $,2n) and ($\gamma $,4n) are in good agreement with theory, while in the case of reactions ($\gamma $,n), ($\gamma $,3n), and ($ \gamma $,5n), some discrepancies are observed. The results obtained for the reactions ($\gamma $,n), ($\gamma $,3n) and ($\gamma $,4n) are in satisfactory agreement with the known literature data. The average cross sections for the reactions ($\gamma $,2n) and ($\gamma $,5n) and the isomeric ratios of the reaction products $^{\text{93}}$Nb($\gamma $,5n)$^{\text{88m,g}}$Nb were measured for the first time.