Neutron scattering from a copper sample was measured at Rensselaer Polytechnic Institute utilizing the quasi-differential method. The measurement spanned the energy range from 0.5 to 20 MeV using the high-energy scattering system and from 2 keV to 0.5 MeV using the new mid-energy scattering system. Copper was selected as a material of interest to measure due to large discrepancies between experiments and simulations of the Zeus benchmark. The Zeus benchmark consists of a copper reflected highly enriched uranium system, and the angular distribution of copper scattering was thought to potentially be the cause of the discrepancy. The copper measurements found differences in the scattering response particularly in the incident energy region from 1 to 2 MeV for the high-energy measurement and from 2 to 4 keV in the mid-energy system. These differences are particularly noticeable at angles near 90 deg in the high-energy system and back angles in the mid-energy system. Additionally, for ENDF/B-VIII.0 there is a large discrepancy at the forward angle in the energy range around 0.5 MeV. For these reasons, a new evaluation of copper scattering utilizing these results is recommended and perhaps could help to improve the agreement with the Zeus benchmarks.

The electron linear accelerator housed in the Gaerttner Linear Accelerator Center at Rensselaer Polytechnic Institute was used to generate a pulsed neutron source to measure the neutron total cross section of tantalum, titanium, and zirconium from 0.4 to 25 MeV. Neutron transmission measurements were made using the time-of-flight method with neutron flight paths of approximately 100 and 250 m. The long flight paths combined with narrow neutron pulse widths, fast detector responses, fast electronics, and data collection system provide good energy resolution for the measurements. A high signal-to-background ratio through much of the energy range combined with low statistical errors resulted in low uncertainties on cross sections. The results are presented and compared with the major nuclear data evaluations. Each measurement identifies regions where the neutron total cross sections could be reevaluated. The total cross-section measurements presented here can help nuclear data evaluators improve neutron total cross-section data in future evaluations.

A new array of four Deuterated Benzene (C6D6) detectors has been installed at the Gaerttner Linear Accelerator Center at Rensselaer Polytechnic Institute for the purpose of measuring neutron capture cross sections in the keV region. Measurements were performed on samples of Ta-181 in the unresolved resonance region (URR) using a filtered-beam technique, by which a 30 cm iron filter was placed in a white-spectrum neutron beam to remove all time-dependent. gamma-ray background and all neutrons except those transmitted through resonance-potential interference "windows" in the iron. The resulting filtered beam was effectively a quasimonoenergetic neutron source, which was used for performing measurements on isotopes with narrow level spacings in the URR. The capture cross-section results obtained for two thicknesses of tantalum are in agreement with those documented in the JEFF-3.2 library, as are the average resonance parameters obtained via a fit to the data using the SAMMY-FITACS code.

Rhenium is a refractory metal with potential uses in nuclear reactor applications, particularly those at very high temperatures. Measurements have been made using natural samples. Natural rhenium consists of two isotopes: Re-185 (37.40%) and Re-187 (62.60%). The electron linear accelerator (LINAC) at the Rensselaer Polytechnic Institute (RPI) Gaerttner LINAC Center was used to explore neutron interactions with rhenium in the energy region from 0.01 eV to 1 keV. Neutron capture and transmission measurements were performed by the time-of-flight technique. Two transmission measurements were performed at flight paths of 15 m and 25 m with Li-6 glass scintillation detectors. The neutron capture measurements were performed at a flight path of 25 m with a 16-segment sodium iodide multiplicity detector. Resonance parameters were extracted from the data using the multilevel R-matrix Bayesian code SAMMY. A table of resonance parameters and their uncertainties is presented. The uncertainties in resonance parameters were propagated from a number of experimental quantities using a Bayesian analysis. Uncertainties were also estimated from fitting each Re sample measurement individually. The measured neutron capture resonance integral for Re-185 is (4 +/- 1)% larger than ENDF/B-VII.1. The capture resonance integral for Re-187 is (3 +/- 1)% larger than ENDF/B-VII.1. Other findings from these measurements indude: a decrease in the thermal capture cross section for Re-185 of (2 +/- 2)% from ENDF/B-VII.1; a decrease in the thermal capture cross section for Re-187 of (3 +/- 4)% from ENDF/B-VII.1; a decrease in the thermal total cross section for Re-185 of (2 +/- 2)% from ENDF/B-VII.1; and a decrease in the thermal total cross section for Re-187 of (6 +/- 5)% from ENDF/B-VII.1. Considering the uncertainties, none of the indicated changes in thermal cross sections represents a statistically significant change from ENDF/B-VII.1. (C) 2017 Elsevier Ltd. All rights reserved.

Scattering experiments performed with the Rensselaer Polytechnic Institute Linear Accelerator measured elastic and inelastic scattering from an elemental iron sample. Eight liquid scintillator (EJ-301) proton recoil fast neutron detectors were positioned at several angles 0.5m from the scattering sample. Data were measured using neutron time-of-flight in the energy range from 0.5 to 20MeV, and pulse shape analysis was used to discriminate neutrons from gamma-rays. Nuclear data evaluations were compared to experimental data using Monte Carlo calculations. Below 2MeV two new techniques were developed: a method which assessed inelastic-to-elastic scattering ratios and a method to determine the contribution from neutrons after only elastic scattering. These techniques, along with time-of-flight results, may help identify specific reactions that account for differences between evaluations and experimental data.

The U-236 isotope is an important buildup product that is generated in the U-235 fuel cycle and influences reactor neutronic calculations. The aim of the present work is to improve upon the existing neutron total cross section data for the strong U-236 resonance at 5.467 eV.High accuracy neutron transmission measurements were performed using the time-of-flight technique at the Rensselaer Polytechnic Institute linear accelerator. An approach was used to fabricate thin U-236 samples using liquid, allowing for non-saturated resonances. The transmission measurements were made at the 15 m flight station with a Li-6 glass scintillation detector. Methods to characterize the background and experimental resolution function were developed. The U-236 resonance parameters and their uncertainties at 5.467 eV were determined by fitting the transmission data using a Monte Carlo approach with the SAMMY multi-level R-matrix Bayesian code.The resonance parameters determined in this work are: energy, E, equal to 5.467 +/- 0.005 eV; neutron width, Gamma(n), equal to 2.13 +/- 0.04 meV; and radiation width, Gamma(gamma), equal to 27 +/- 1 meV. The fission width, Gamma(f), was not fitted and was fixed to the ENDF-7.1 value of 0.290 meV. These parameters gave a neutron capture resonance integral of 330 +/- 5 b that is lower than all of the selected evaluations: Mughabghab by 4.7%, ENDF-7.1 by 3.7%, JEFF-3.1 by 4.8%, and JENDL-4.0 by 7.2%. (C) 2015 Elsevier Ltd. All rights reserved.

Few experimental measurements of the (n, γ) cross section exist for iron above the first inelastic state of Fe at 847 keV. Because capture measurements rely on the detection of prompt photon cascades emitted by the de-excitation of the compound nucleus, it is challenging to separate the capture signal from photons generated in inelastic scattering events. A new array of C6D6 detectors at the Gaerttner Linear Accelerator Center at Rensselaer Polytechnic Institute has enabled the straightforward separation of the radiative capture and inelastic scattering signals in a sample of natural iron through the use of digital filtering and analysis. These techniques have enabled the extension of iron experimental data to energies of 2500 keV. Results show good agreement with the ENDF/B-VII.1 and JEFF-3.2 evaluations to 1500 keV.