Photo-neutron cross-section of $${}^{{\mathrm {nat}}}{\mathrm {Dy}}$$ nat Dy in the bremsstrahlung end-point energi

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Regular Article - Experimental Physics

Photo-neutron cross-section of nat Dy in the bremsstrahlung end-point energies of 12, 14, 16, 65, and 75 MeV H. Naik1, G. N. Kim2,a , R. Schwengner3 , Wooyoung Jang2 , N. T. Hien2 , K. Kim2 , S. G. Shin4 , Y. Kye4 , A. Junghans3 , A. Wagner3 , M.-H. Cho4 1

Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India Department of Physics, Kyungpook National University, Daegu 41566, Republic of Korea 3 Institut of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany 4 Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea

2

Received: 4 March 2020 / Accepted: 5 October 2020 © Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Communicated by Takashi Nakamura

Abstract The flux-weighted average cross-sections of nat Dy(γ, xn)159,157,155 Dy reactions were measured at the bremsstrahlung end-point energies of 12, 14, 16, 65 and 75 MeV with the activation and off-line γ-ray spectrometric technique using the 20 MeV Electron Linac for beams with high Brilliance and low Emittance (ELBE) at HelmholtzZentrum Dresden-Rossendorf, Dresden, Germany and the 100 MeV electron linac at the Pohang Accelerator Laboratory, Korea. The nat Dy(γ, xn)157,155 Dy reaction crosssections as a function of photon energy were also calculated theoretically using TALYS 1.9 code. Then the flux-weighted average values at different end-point energies were obtained based on the theoretical values of mono-energetic photons. These values were compared with the flux-weighted values of present work and are found to be in general agreement. It was also found that the experimental and theoretical formation cross sections of 159 Dy, 157 Dy and 155 Dy from the nat Dy(γ, xn) reactions increased from their respective threshold values to a certain energy where other reaction channels opened. After reaching a maximum value, the individual reaction cross-sections slowly decreased with the increase of the bremsstrahlung energy due to the initiation of other competing reactions at higher energy, which indicates the impact of the excitation energy. However, the production cross sections of 157 Dy and 155 Dy from the nat Dy(γ, xn) reactions slightly increase in between and then decreased slowly with bremsstrahlung energy, which is due to the contributing reactions of higher mass isotopes.

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1 Introduction Studies on the nuclear reactions of different elements induced by photons, neutrons, and charge particles provide a basic understanding of the nuclear structure and properties of the element such as the excitation numbers, level densities, ground-state deformations, γ-ray strength functions, and decay schemes. These properties are necessary for the calculation of reaction cross-sections using different simulation codes. The nuclear reaction cross-section is a function of the excitation energy, i.e. the excitation function, and is very sensitive to the density at the nuclear