Determination of (n,γ) Cross Sections of 241Am by PGAA

Accurate cross section data of actinides are crucial for criticality calculations of GEN IV reactorsand transmutation but also for analytical purposes such as nuclear waste characterization, decommissioningof nuclear installations and safeguard applications. Tabulated data are inconsistent andsometimes associated with large uncertainties. In beam techniques, like prompt gamma activationanalysis (PGAA) using external neutron beams from high ux reactors oer a chance for determinationof absolute partial -ray production cross sections with a minimum of uncertainty to around2 to 3 %. Preliminary experiments have been conducted at FRM II, Garching, Germany to investigatethe potential of PGAA for accurate cross section determination of actinides using well prepared241Am sources.Preparation of samples for irradiation at the Budapest Reactor and FRM II in Garching ofthe 241Am sources has been optimized together with PTB in Braunschweig. Two samples wereirradiated together with a gold ux monitors to extract the thermal neutron capture cross sectionafter appropriate corrections for attenuation of neutrons and photons in the sample.For one sample the thermal ground state neutron capture cross section was measured as649:9 28:2 b. The total thermal neutron capture cross section was calculated to 711:1 33:9 b.For the other sample a ground state neutron capture cross section of 663:0 28:8 b and a total crosssection of 725:4 34:4 b was measured