New 209Bi photodisintegration data and physical criteria of data reliability

Sergey Belyshev,Hiroaki Utsunomiya,Aleksandr Kyznetsov,Dan Filipescu,Konstantin Stopani,Boris Ishkhanov,Alexander Davydov,Vadim Orlin,Vladimir Varlamov,Ioana Gheorghe

doi:10.1051/epjconf/202023901031

Abstract

The well-known problem of noticeable disagreements between photoneutron cross sections from various experiments was discussed in detail for 209Bi. Data for partial photoneutron reactions cross sections obtained at Livermore (USA) using quasimonoenergetic annihilation photons and the method of neutron multiplicity sorting were analyzed using the objective physical criteria and the experimental-theoretical method for evaluation. Because of significant systematic uncertainties involved in the method for determining the neutron multiplicity, experimental data do not satisfy the criteria of reliability and differ noticeably from the evaluated data. The new experimental data for 209Bi (γ, in) reactions with i = 1–4 were obtained using quasimonochromatic laser Compton-scattering (LCS) γ-ray beams at the NewSUBARU synchrotron radiation facility and the novel technique of direct neutron-multiplicity sorting with a flat-efficiency detector. It was found that new σ(γ, 1n), σ (γ, 2n), and σ (γ, 3n) contradict noticeably to the Livermore data. It was shown that at the same time the new 209Bi photoneutron cross-sections are in good agreement with data evaluated using experimental-theoretical method and assuring the reliability of those.

Highlights

The major part of experimental data for the total and partial photoneutron reaction cross sections consists of those from Livermore (USA) and Saclay (France), which were obtained by the quasimonoenergetic annihilation photons and the photoneutron multiplicity sorting technique [1]
It is obvious that the discrepancy between the Livermore and Saclay data could not be removed by applying a constant normalization factor. It was shown [4,5,6,7,8,9,10,11,12,13,14] that the reasons are the definite shortcomings of neutron multiplicitysorting method based on the idea that energies of neutrons from the partial reactions are noticeably different and neutron multiplicities could be deduced from its measured kinetic energies
Not dependent on the experimental neutron multiplicity sorting because includes all outgoing neutrons was decomposed into the partial reaction cross sections, σeval(γ, in) = Fitheor × σexp(γ, S n) using the transitional neutron multiplicity functions, Fi(γ, in) = σ(γ, in)/σ(γ, S n) calculated within the framework of the Combined photonucleon reaction model (CPNRM) [15] for the partial reactions (γ, in) with definite neutron multiplicity factors i = 1, 2, 3

Summary

Introduction

The major part of experimental data for the total and partial photoneutron reaction cross sections consists of those from Livermore (USA) and Saclay (France), which were obtained by the quasimonoenergetic annihilation photons and the photoneutron multiplicity sorting technique [1]. . The ratios Fiexp(γ, in) (3) were proposed as the objective physical criteria of experimental partial photoneutron reaction cross-section data reliability.

Results

Conclusion