Neutron capture studies of 206Pb at a cold neutron beam

Gamma-ray transitions following neutron capture in 206Pb have been studied at the cold neutron beam facility of the Budapest Neutron Centre using a metallic sample enriched in 206Pb and a natural lead nitrate powder pellet. The measurements were performed using a coaxial HPGe detector with Compton suppression. The observed gamma-rays have been incorporated into a decay scheme for neutron capture in 206Pb. Partial capture cross sections for 206Pb(n,g) at thermal energy have been derived relative to the cross section for the 1884 keV transition after neutron capture in 14N. From the average crossing sum a total thermal neutron capture cross section of 29+2-1 mb was derived for the 206Pb(n,g) reaction. The thermal neutron capture cross section for 206Pb has been compared with contributions due to both direct capture and distant unbound s-wave resonances. From the same measurements a thermal neutron induced capture cross section of (649 +/- 14) mb was determined for the 207Pb(n,g) reaction.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

A Measurement of (n,xngamma) Cross Sections for 208Pb from Threshold up to 20 MeV

Gamma production cross sections for neutron inelastic scattering, (n,2ngamma) and (n,3ngamma) reactions on 208Pb were measured at the Geel Electron Linear Accelerator (GELINA) from the respective thresholds up to at most 20 MeV. An unprecedented neutron energy resolution of 1.1 keV at 1 MeV (35 keV at 10 MeV) and a total uncertainty of about 5% was achieved for the integral gamma production cross section of the most intense transition in 208Pb. The gamma production cross section was measured for 29 transitions of the inelastic channel, 5 transitions of the (n,2ngamma) channel and one transition of the (n,3ngamma) channel. Based on the evaluated level scheme of 208Pb, the total neutron inelastic scattering cross section and the level cross sections were deduced. Four large volume HPGe (high purity germanium) detectors were used for the detection of the gamma-rays. The 88.11% enriched 208Pb sample was placed at a flight path length of 198.551 m. The cross sections were measured relative to the standard cross section by continuously monitoring the neutron flux with a fission chamber containing 235U. The results are compared with the existing experimental data from the literature and with model estimates obtained with the recent TALYS 1.00 code. A good agreement of the present data is found with both the existing experimental data and with the calculations. The present work greatly expands the number of measured gamma production cross sections and the level cross sections derived for this nucleus.JRC.D.5-Neutron physic