Neutron Transmission Measurements at nELBE

Neutron total cross sections are an important source of experimental data in the evaluation of neutron induced cross sections. The sum of all neutron-induced reaction cross sections can be determined with a precision of a few percent in a relative measurement. The transmission is determined from the count rates of the neutron beam transmitted through a target sample relative to the count rate without sample and is independent of the neutron detection efficiency. The neutron spectrum of the photo neutron source nELBE extends in the fast region from about 100 keV to 10 MeV and has favourable conditions for transmission measurements due the low instantaneous flux of neutrons and low gamma-flash background. Several materials of interest (in part included in the CIELO evaluation or on the HPRL of OECD/NEA) have been investigated: 197Au, natFe, natW, 238U, natPt, 4He, natO, natNe, natXe. For gaseous targets high pressure gas cells have been built that hold up to 200 bar pressure. The experimental setup will be presented including results from several transmission experiments and the data analysis leading to the total cross sections will be discussed.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard