The Nuclear Science and Engineering Research Center (NSERC), a Defense Threat Reduction Agency (DTRA) office located at the United States Military Academy (USMA), sponsors and manages cadet and faculty research in support of DTRA objectives. Cadets in the Department of Physics and Nuclear Engineering at USMA are using pyroelectric crystals to ionize and accelerate residual gas trapped inside a vacuum system. A system using two lithium tantalate crystals with associated diagnostics was designed and is now operational. X-ray energies of approximately 150 keV have been achieved. Future work will focus on developing a portable neutron generator using the D-D nuclear fusion process.

The Nuclear Science and Engineering Research Center (NSERC), a Defense Threat Reduction Agency (DTRA) office located at the United States Military Academy (USMA), sponsors and manages cadet and faculty research in support of DTRA objectives. The NSERC has created an experimental pyroelectric crystal accelerator program to enhance undergraduate education at USMA in the Department of Physics and Nuclear Engineering. This program provides cadets with hands-on experience in designing their own experiments using an inexpensive tabletop accelerator. This device uses pyroelectric crystals to ionize and accelerate gas ions to energies of similar to 100 keV. Within the next year, cadets and faculty at USMA will use this device to create neutrons through the deuterium-deuterium (D-D) fusion process, effectively creating a compact, portable neutron generator. The double crystal pyroelectric accelerator will also be used by students to investigate neutron, x-ray, and ion spectroscopy.

The electron linear accelerator facility at the Rensselaer Polytechnic Institute was used to explore neutron interactions with molybdenum in the energy region from 10 eV to 2 keV. Neutron capture and transmission measurements were performed by the time-of-flight technique. 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. Two transmission measurements were performed at a flight path of 25 in with a (6)Li glass scintillation detector. The neutron capture measurements were performed at a flight path of 25 m with a 16-segment sodium iodide multiplicity detector. Nine different thicknesses of elemental molybdenum metal samples ranging from 0.051 mm (0.002 in.) to 6.35 mm (0.250 in.) were measured in either capture or transmission. Reductions in resonance integrals were observed when compared to ENDF/B-VII.0 for six of the seven stable isotopes. The largest reductions were 9% in (97)Mo and 11% in (100)Mo. The one measured increase in resonance integral relative to ENDF/B-VII.0 occurred in (95)Mo, and it was significant (10%). The measured distribution of neutron widths for (95)Mo and (97)Mo are a better match to a Porter-Thomas distribution than those of ENDF/B-VII.0. Neutron strength functions for (95)Mo and (97)Mo were measured and compared to ENDF/B-VII.0. The strength of (95)Mo and (97)Mo are within uncertainties of each other. The measured radiation width distribution for (95)Mo and (97)Mo are compared to those of ENDF/B-VII.0 and to chi(2) distributions. Significant aspects of this analysis are the assignment of radiation widths, the determination of the transmission resolution function, and the propagation of experimental uncertainties into resonance parameter uncertainties.

The purpose of this work was to measure the neutron cross sections of molybdenum accurately. The Rensselaer Polytechnic (RPI) LINAC facility was used to measure the neutron interaction cross sections of molybdenum. Neutron capture time-of-flight measurements were made at 25 m with a sodium iodide multiplicity detector. Transmission measurements were performed at 25 m flight with a Li-6 glass scintillation detector. Nine different thicknesses of elemental molybdenum metal samples ranging from 0.051 mm (0.002 in.) to 6.35 mm (0.250 in.) were measured in either capture or transmission. Data from two transmission and one capture measurement have been analyzed using the multilevel R-matrix Bayesian code SAMMY. Throughout the energy spectrum, 10-2000 eV, resonance widths have been attained. Between one and two keV, the width assignments of overlapping resonances were obtained and compared to ENDF/B-VII.0. ENDF/B-VII.0 nuclear radii fit the transmission data between resonances better than those of ENDF/B-VI.8. Below 600 eV, the inclusion of capture data in the fit enhanced our ability to determine radiation widths compared to using transmission data alone.

Current burnable absorbers such as boron carbide placed in the control rod guide tubes of fresh fuel assemblies create a water displacement penalty at end of cycle (EOC) that reduces the overall maximum cycle length of the reactor. Other burnable absorbers such as gadolinium-oxide mixed in the fuel do not create the water displacement penalty but create a lower centerline melt temperature for the fresh fuel and reduce the overall enrichment for the assembly. This research proposes using a transuranic (TRU) isotope with a relatively high absorption cross section such as Pu-240 to reduce excess criticality within the reactor at beginning of cycle. The added benefit of using this TRU isotope over a standard burnable absorber is that when it absorbs a neutron it no longer negatively affects the criticality of the reactor, and it will transmutate into a fissile material that will add to the overall criticality of the reactor at EOC.

Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic Institute LINAC using metallic zirconium samples. The capture measurement was made at the 25-m flight station with a multiplicity-type capture detector, and the transmission total cross-section measurements were performed at the 25-m flight station with a Li-6 glass scintillation detector. Resonance parameters were determined by a combined analysis of all 11 data sets (4 capture and 7 transmission) using the least-squares multilevel R-matrix code REFIT.The present measurements were undertaken to resolve discrepancies between common usage (ENDF/B-VI) and the recent measurements of Salah et al. for the 300-eV zirconium doublet. The present measurements support the Salah et al. conclusions. Specifically, the results confirm the assignment of J = 3 for the Zr-91 292.5-eV resonance and include all significant resonances up to 2.5 keV: The zirconium resonance parameters Gamma(gamma) and Gamma(n), determined in the present measurement, are compared with the ENDF/B-VI parameters.

Two new photoneutron targets have been developed for neutron time-of-flight experiments, the axial water-moderated target (AWMT) and the bare bounce target (BBT). These targets operate without any lead shielding nearby and both have superior neutron resolution compared to the older bounce target. The BBT has been selected over the AWMT for general time-of-flight measurements because it exhibited lower neutron background in the keV energy region.

A sixteen-segment NaI(TI) multiplicity gamma ray detector is used at the Rensselaer Polytechnic Institute Gaerttner LINAC Laboratory for neutron cross section measurements. This detector consists of an annulus of NaI(TI) divided into two sets of 8 pie-shaped segments, each segment optically isolated and viewed by a photomultiplier. The neutron beam passes along the axis of the detector and impinges upon a sample placed in the center. Time-of-flight data are taken as a function of the number of sections which detect a gamma and which is defined as the detected multiplicity. This detector can simultaneously acquire neutron scattering, capture and fission data by placing suitable limits on the total detected gamma ray energy deposited in the detector. Scattering and capture measurements have been performed on samples of holmium, erbium, and tungsten and experimental results are presented. The experimental multiplicity for capture is analyzed by assuming the single particle model, stochastically calculating the gamma ray cascades from neutron capture, and transporting each gamma ray into the detector using the Monte Carlo method. The detection efficiency for neutron capture is over 90% and is relatively insensitive to different isotopes of the same element or different spins of the compound nuclear resonances. A status report on experimental and analytical activities at the Laboratory is presented.