This project sought to further our understanding of non-Local Thermodynamic Equilibrium (NLTE) processes by providing benchmark data to validate computational models. This has been a difficult regime to study in the laboratory, where experimental scales produce strong gradients while interpretation requires well-characterized uniform plasmas. It has also been a difficult regime to simulate, as evidenced by the large discrepancies in predictions of NLTE spectra for fixed plasma properties. Not surprisingly, discrepancies between data and calculations of recombining laser-produced plasmas have been in evidence since the 1980's. The goal here was to obtain data of sufficient accuracy to help resolve these discrepancies and enable better modeling of the NLTE processes that are integral to high-energy density experiments. Advances in target fabrication, diagnostic development and simulation capabilities provided the foundations for this project. Uniform plasmas were to be achieved by using aerogel foams of low enough density ({approx}mg/cm{sup 3}) and thickness ({approx}mm) to be volumetrically heated by a laser. The foams were doped with Ti to provide K- and L-shell emission and recombination spectra during the experiments. A new absolutely calibrated transmission grating spectrometer provided absolute temporal measurements at 18 frequencies, in addition to a CCD image of the time-integrated spectrum. Finally, …

A prompt gamma-ray neutron activation analysis (PGNAA) system was evaluated for the quantification of chlorinated compounds in soil. The system evaluation was divided into two phases. In phase one, the response of an n-type HPGe detector (20 percent relative efficiency) to point sources of 60Co and 152Eu was determined experimentally and used to calibrate an MCNP4a model of the detector. The refined MCNP4a detector model can predict the absolute peak detection efficiency within 7 percent in the energy range of 120 - 1400 keV. In phase two, a PGNAA system consisting of a light-water moderated 252Cf (1.06 mg) neutron source, and the shielded and collimated HPGe detector was used to collect prompt gamma-ray spectra from Savannah River Site (SRS) soil spiked with chlorine. The experimental system response was used to calculate the minimum detectable concentration of chlorine in the SRS soil for a 1800 sec. irradiation as 2200 mg/g based on the analysis of the 788 keV gamma-ray. MCNP4a was used to predict the PGNAA system response, which was accomplished by analyzing the neutron and gamma ray transport components separately. In the energy range of 788 to 6110 keV, the MCNP4a predictions were generally within 60 percent of the calculated …

This report is on Selected Profiles of Future Technology in Urban Settings: Informational and Behavioral Developments.