Prompt gamma rays induced by inelastic scattering of fission neutrons on iron

Abstract

Prompt gamma rays induced by (n,n′γ) reactions on iron were measured with the instrument FanGaS (Fast Neutron induced Gamma-Ray Spectrometry) operated at the Heinz Maier-Leibnitz Zentrum (MLZ) in Garching. The measurement was performed at an angle of 90° between neutron beam and detector. The fast neutron flux at the sample position was determined to be 1.40 × 108 cm−2 s−1 by using the foil activation method. Energies, relative intensities and fast neutron spectrum averaged isotopic cross section for production of 81 prompt gamma lines are presented. The results obtained are found in good agreement with literature data. The new set of gamma lines is recommended to replace the old dataset with several new lines also recognizing a few false identifications. This work is an important step towards the future chemical analysis of large samples at FanGaS employing highly penetrating fission neutrons.

The Baghdad Atlas: A relational database of inelastic neutron-scattering (n,n′γ) data

“…where E FRM n denotes the FRM-II neutron expectation energy [32], we find that our scaled cross sections σ γi S are in agreement with those from the FRM-II, i.e., σ γi S ≈ σ γi FRM as shown in Table 4.…”

“…Although our results are significantly smaller, Table 4 shows that all results are in proportion. The absolute differences, however, are not surprising given a much higher average neutron energy of 2.3 MeV in the FRM-II measurement [32], while our kToptimized flux-weighted neutron expectation energy is only 0.631 MeV according to Eq. ( 26), whereupon we replace the lower-limit E th with E = 0.…”

“…This property of (n, n ) has made it an attractive area of study to many research groups in the international nuclear science community. This is exemplified by the plethora of papers on 56 Fe(n, n γ) by groups from Russia [41], Los Alamos [42,43], GELINA [44], Dresden [45], and FRM-II [32].…”

“…Because the γ-ray intensities (or cross sections) are correlated, a covariance matrix V is needed Table 4: Optimized flux-weighted angular-distribution-corrected γ-ray production cross sections ( σγ W ) for the three strongest transitions in 56 Fe, deduced assuming the best-fit value kT = 0.155 MeV. For comparison, the corresponding average fluxweighted cross sections ( σγ FRM ) obtained from the FRM-II measurement [32] are also listed. The final column shows the Baghdad Atlas cross sections scaled by the ratio of expectation energies deduced from the two facilities in accordance with Eq.…”

“…An additional limitation of the current method is that the 56 Fe data are only sensitive to neutron energies above the excitation threshold of 861.9 keV. As a final consideration, we can also compare our kT -optimized flux-weighted cross sections to those from the recent 56 Fe(n, n γ) measurement using the Fast Neutron-induced Gamma Spectrometry (FaNGaS) setup at the FRM-II (Forschungs-Neutronenquelle Heinz-Maier-Leibnitz) research reactor by Ilic [32], where they have also determined average flux-weighted angular-distribution-corrected cross sections for the 846.8-, 1238.3-and 1810.8-keV γ rays; presented in Table 4 for comparison. Although our results are significantly smaller, Table 4 shows that all results are in proportion.…”