Overview of Experimental Nuclear Data Research at RPI

Accurate nuclear data is an important ingredient required for accurate neutron transport calculations in a variety of applications. Current nuclear physics models require experimental data in order to provide nuclear data with sufficient accuracy for applications. The Gaerttner Linear Accelerator (LINAC) Center at Rensselaer Polytechnic Institute (RPI) has been activelymeasuring nuclear data for applications since the accelerator commenced operations in 1961. The electron LINAC is used to produce short neutron pulses required for neutron time-of-flight measurements. A major upgrade project that will increase the neutron production by a factor of about 10 is ongoing with expected completion in 2020. Current measurement capabilities cover the energy range from thermal to 20 MeV and include total, capture, fission, (n, alpha), and scattering reactions. The RPI gamma-multiplicity detector which is a nearly 4π segmented gamma detector was recently used for simultaneous fission and capture measurement of 235U in the 0.01 eV to 3 keV energy region. This measurement helped resolve a discrepancy between ENDF/B-7.1 and JENDL-4.0 evaluations. A detector array for fast neutron scattering and angular distributions enabled measurement of 238U, Fe, Mo, Be, Zr, and Pb. Some of these measurements were used in the new ENDF/B-8.0 evaluation. Recently we performed a similar scattering experiment for 235U and 239Pu at Los Alamos National Laboratory. A unique capability at RPI is the Lead Slowing-Down Spectrometer (LSDS). This spectrometer creates an intense neutron flux in the eV to keV range that enables measurements on small samples or samples with small cross sections. Recent measurements with the LSDS include: fission cross section, fission fragment yields, (n, alpha) cross sections, and neutron capture yields. All described experimental systems were designed and constructed by graduate and undergraduate students which thus gain valuable experience in nuclear data, data acquisition and analysis, and neutron transport methods used to optimize and compare with the experiments. A review of some of the capabilities and recent results will be presented.