We are developing gamma-ray detectors with a bulk absorber and a superconducting transition-edge sensor. The absorber is high purity Sn and the transition-edge sensor is a Mo/Cu multilayer thin film. We have characterized the detector, and will discuss x-ray and gamma-ray results.

The ''Extreme Ultraviolet Explorer'' satellite observed the cataclysmic variable OY Carinae in superoutburst for 3 days in March 1997. The resulting 80-180 {angstrom} spectrum, which contains broad (FWHM {approx} 2000 km s{sup -1}) emission lines of O V-VI, Ne V-VI, Mg V-VI, and Fe VI-VIII, is well modeled by scattering of boundary layer radiation in the system's accretion disk wind.

We have recently completed a two-year study of recirculating induction heavy-ion accelerators (recirculators) as low-cost drivers for inertial-fusion-energy power plants. We present here a summary of that study and other recent work on recirculators.

Photon-atom scattering is important in a variety of applications, but scattering from a composite system depends on the accurate characterization of the scattering from an isolated atom or ion. We have been examining the validity of simpler approximations of elastic scattering in the light of second-order S-matrix theory. Partitioning the many-body amplitude into Rayleigh and Delbrueck components, processes beyond photoionization contribute. Subtracted cross sections for bound-bound atomic transitions, bound pair annihilation, and bound pair production are required in anomalous scattering factors for: (1) convergence of the dispersion integral; (2) agreement with predictions of the more sophisticated S-matrix approach; (3) satisfying the Thomas-Reiche-Kuhn sum rule. New accurate tabulations of anomalous scattering factors have been prepared for all Z, for energies 0--10,000 keV, within the independent particle approximation (IPA) using a Dirac-Slater model of the atom. Separately, experimental atomic photoabsorption threshold information has been used to modify these IPA predictions for improved comparison with experiment.

To build a bridge with customers, we balance the linear modeling process with the dynamics of the individuals we serve, who may feel unfamiliar, even confused, with that process. While it is recognized that human factors engineers improve the physical aspect of the workplace, they also work to integrate customers` cognitive styles, feelings, and concerns into the workplace tools. We take customers` feelings into consideration and integrate their expressed needs and concerns into the modeling sessions. After establishing an agreeable, professional relationship, we use a simple, portable CASE tool to reveal the effectiveness of NIAM. This tool, Modeler`s Assistant, is friendly enough to use directly with people who know nothing of NIAM, yet it captures all the information necessary to create complete models. The Modeler`s Assistant succeeds because it organizes the detailed information in an enhanced text format for customer validation. Customer cooperation results from our modeling sessions as they grow comfortable and become enthused about providing information.

This paper presents a graphics renderer which incorporates new partitioning methodologies of memory and work for efficient execution on a parallel computer. The Task Adaptive domain decomposition scheme is an image space method involving dynamic partitioning of rectangular pixel area tasks. The author shows that this method requires little overhead, allows coherence within a parallel context, handles worst case scenarios effectively, and executes efficiently with little processor synchronization necessary. Previous research in the area of memory and work decompositions for graphics rendering has been primarily limited to simulation studies and little practical experience. The algorithm presented here has been implemented on a scalable distributed memory multiprocessor and tested on a variety of input scenes. The author presents a theoretical and practical analysis in order to contrast its predicted and actual success. The implementation analysis indicates that load imbalance is the major cause of performance degradation at the higher processor counts. Even so, on a variety of test scenes, an average rendering speedup of 79 was achieved utilizing 96 processors on the BBN TC2000 multiprocessor with a processor efficiency range of 66% to 94%.

We report improvement of the polarization diagnostics and their use in the development of the Optically Pumped Polarized Ion Source (OPPIS).

Prior to 1988, a variety of materials were buried on the US DOE Oak Ridge Reservation. Records of the disposal operations are incomplete and toxic materials may have been placed adjacent to potential explosives. One of the safety concerns in conducting an environmental restoration project at the burial sites, is the possibility of an explosion which could release toxic materials to the atmosphere. A safety analysis examined the consequences of such releases by first postulating an upper bound for the strength of an explosive. A correlation, developed by Steindler and Seefeldt of Argonne National Laboratory, was then used to estimate the amount and particle-size distribution of the material that could become airborne from the explosion. The estimated amount of airborne material was the source term in an atmospheric dispersion model which was used to calculate infinite-time, concentration-time integrals and 5-minute, time- weighted average concentrations at locations down-wind from the explosion. The dispersion model includes particle deposition as a function of particle-size distribution class. The concentration-time integrals and average concentrations were compared to published guidelines to assess the consequences of an accidental explosion.

None

The local-density approximation provides a proper setting for the decomposition of total energy into many-body (many-atom) contributions. Multiple scattering theory in turn provides a convenient framework for carrying out this process. We illustrate this concept with calculations on a linear chain of atoms in bulk copper.

I describe an automated approach to partial evaluation based on simplification and implemented by program transformations. The approach emphasizes program algebra and relies on canonical forms and distributive laws to expose instances to which simplifications can be applied. I discuss some of the considerations that led to the design of this approach. This design discussion should be useful both in understanding the structure of the partial evaluation transformations, and as an example of how to approach the design of automated program transformations in general. This approach to partial evaluation has been applied to a number of practical examples of moderate complexity, including: the running example used in this paper, proving an identity for lists, and eliminating a virtual data structure from a specification of practical interest. The chief practical barrier to its wider application is the growth of the intermediate program text during partial evaluation. Despite this limitation, this approach has the virtues of being implemented, automated, and able to partially evaluate specifications containing implicit data, including some specifications of practical interest.

We have modeled gyrotron windows and gyrotron amplifier sever structures for TE modes in the 100--150 GHz range and have computed the reflection and transmission characteristics from the field data. Good agreement with frequency domain codes and analytic analysis have been obtained for some simple geometries. We present results for realistic structures with lossy coatings and describe implementation of microwave diagnostics.

We have completed a fifteen year, referenced and documented compilation of more than 15,000 measurements of laser-induced damage thresholds (LIDT) conducted at the Lawrence Livermore National Laboratory (LLNL). These measurements cover the spectrum from 248 to 1064 nm with pulse durations ranging from < 1 ns to 65 ns and at pulse-repetition frequencies (PRF) from single shots to 6.3 kHz. We emphasize the changes in LIDTs during the past two years since we last summarized our database. We relate these results to earlier data concentrating on improvements in processing methods, materials, and conditioning techniques. In particular, we highlight the current status of anti-reflective (AR) coatings, high reflectors (HR), polarizers, and frequency-conversion crystals used primarily at 355 nm and 1064 nm.

In this paper, we propose a method for calculating the similarity between two digital images. A global signature describing the texture, shape, or color content is first computed for every image stored in a database, and a normalized distance between probability density functions of feature vectors is used to match signatures. This method can be used to retrieve images from a database that are similar to an example target image. This algorithm is applied to the problem of search and retrieval for database containing pulmonary CT imagery, and experimental results are provided.

The goal of the continuous air monitor (CAM) system at the Los Alamos National Laboratory`s Plutonium Facility (PF-4) is to have a flow rate of 1 cubic feet per minute (cfm) drawn through the CAMs. However, design limitations in the house vacuum result in many CAMs having less than 1 cfm being drawn through them. Reduced flow rates through CAMs present a compromise in worker protection. Laboratory Health and Safety personnel and DOE officials established a flow rate of 0.5 cfm or less as operationally unacceptable. This report quantitatively estimated the difference in risk to workers from a reduced flow rate of 0.5 cfm relative to the risk inherent with a flow rate of 1 cfm. I calculated risk in terms of Committed Effective Dose Equivalent (CEDE) and used units of rem. Estimates for the increase in risk for 0.5 cfm compared to 1 cfm ranged from 0.32 rem to 3.3 rem. The difference in the minimum alarm concentration between 0.5 cfm and I cfm was also compared and was estimated to range from 0.4 rem to 4 rem.

An investigation into the preparation of sol-gel coatings for high power lasers was started at LLNL in 1983 and AR coatings were successfully developed for use in the Nova laser in 1984. Several other large lasers now use these coatings. Subsequent work on HR coatings resulted in AlOOH/SiO{sub 2} and later ZrO{sub 2} or HfO{sub 2}/SiO{sub 2} systems of good optical performance. The use of organic polymer binders gave increased damage threshold and enhanced optical performance. We are in the process of scaling up HR fabrication for substrates approximately 38 cm square. Concurrently we are developing sol-gel random phase plates for laser beam smoothing. These have a patterned surface design of silica which induces phase shifts in the beam by variation in the optical path length. Plates of this type on 80 cm diameter substrates have been used successfully on the Nova.

In order to reach the high fluence goals of the Beamlet laser at Lawrence Livermore National Laboratory (LLNL), the polarizers in the system must be laser conditioned to increase their damage thresholds. Research has shown that by using a six-step raster-conditioning program, the damage thresholds of the HfO{sub 2}/SiO{sub 2} multilayer polarizer coatings can be increased to meet the Beamlet 3-ns design goal of 8 J/cm{sub 2}. Because of the large size of the polarizers (73 cm {times} 37 cm {times} 9 cm), a large-area conditioning facility was constructed capable of rastering a one-meter optic, weighing as much as 400 pounds, at any specified use angle. A large translational stage moves the optic in a raster pattern through a stationary, 10-Hz rep-rated, 1064-nm beam with 10-ns pulses. A scatter measurement diagnostic allows on-the-fly evaluation of laser-induced damage and logs the coordinates of the damage. Laser energy is measured pulse-to-pulse in order to ensure stability during a scan. A small amount of minor coating damage does occur during the process, but the damage does not grow upon further irradiation. This damage causes only a small increase in total scatter compared to that due to the preexisting defects, and would not influence …

Laser induced damage to optical coatings is generally a localized phenomenon associated with coating defects. The most common of the defect types are the well-known nodule defect. This paper reviews the use of experiments and modeling to understand the formation of these defects and their interaction with laser light. Of particular interest are efforts to identify which defects are most susceptible to laser damage. Also discussed are possible methods for stabilizing these defects (laser conditioning) or preventing their initiation (source stabilization, spatter particle trapping).

The Chemical Weapons Convention (CWC) poses problems of constitutionality, of loss of confidential business information, and even of plant safety. An entirely new and complex worldwide regulatory regime, it nevertheless takes account of the need for certainty in the conduct of industrial production. In particular, the CWC provides for site-specific inspection protocols, called {open_quotes}facility agreements{close_quotes}. Facility agreements are not defined in the CWC, but are to be developed as part of the preparations preceding formal entry into force. In effect, they can be thought of as {open_quotes}inspection contracts{close_quotes} governing facilities subject to systematic and routine inspections. Facility agreements are not part of challenge inspections or for cases of alleged use of chemical weapons. The most important fact about facility agreements is that they are not negotiated between the facility owner or operator and the OPCW. Rather, they are negotiated between the State Party and the OPCW. Where United States facilities, such as chemical weapons production facilities, are owned by the government or are under government contract this is not a problem because the government can negotiate on its own behalf. However, where privately owned facilities in the United States enter into facility agreements, the input of those private entities into …

Borehole induction logs were acquired for the purpose of characterizing subsurface physical properties and monitoring steam clean up activities at the Lawrence Livermore National Laboratory. This work was part of the Dynamic Underground Stripping Project`s demonstrated clean up of a gasoline spin. The site is composed of unconsolidated days, sands and gravels which contain gasoline both above and below the water table. Induction logs were used to characterize lithology, to provide ``ground truth`` resistivity values for electrical resistance tomography (ERT), and to monitor the movement of an underground steam plume used to heat the soil and drive volatile organic compounds (VOCs) to the extraction wells.

The Chemical Weapons Convention (CWC) offers a unique challenge to the United States system of constitutional law. This discussion is about the Fourth and Fifth Amendment issues raised by the CWC and about how federal implementing legislation can allow verification inspections to take place in the United States under the Chemical Weapons Convention while remaining in compliance with the Constitution. By implementing legislation, the author means a federal statute that would be enacted separately from Senate approval of the Convention itself. Although implementing legislation is a relatively unusual accompaniment to a treaty, it will be necessary to the CWC, and the Administration has submitted a bill that was under consideration in the last Congress and presumably will be reintroduced early next year. The Fourth and Fifth Amendment problems posed by the CWC arise from the verification inspection scheme embodied in the treaty. The CWC depends heavily on on-site inspections to verify compliance with its key requirements. These include destroying all chemicals weapons stockpiles and bringing potential chemical weapons precursors under international control. The Convention contains four distinct kinds of inspections: systematic inspections of chemical weapons storage and destruction facilities, routine inspections of various declared facilities, challenge inspections, and a variant …

In 1989, radioactive-contaminated metal at the Rocky Flats Plant (RFP) was cleaned using a solvent paint stripper (Methylene chloride). One-third of the radioactive material was able to be recycled; two-thirds went to the scrap pile as low-level mixed waste. In addition, waste solvent solutions also required disposal. Not only was this an inefficient process, it was later prohibited by the Resource Conservation and Recovery Act (RCRA), 40 CFR 268. A better way of doing business was needed. In the search for a solution to this situation, it was decided to study the advantages of using a new technology - pelletized carbon dioxide cleaning. A proof of principle demonstration occurred in December 1990 to test whether such a system could clean radioactive-contaminated metal. The proof of principle demonstration was expanded in June 1992 with a pilot project. The purpose of the pilot project was three fold: (1) to clean metal so that it can satisfy free release criteria for residual radioactive contamination at the Rocky Flats Plant (RFP); (2) to compare two different carbon dioxide cleaning systems; and (3) to determine the cost-effectiveness of decontamination process in a production situation and compare the cost of shipping the metal off site for …

We report improvement of the polarization diagnostics and their use in the development of the Optically Pumped Polarized Ion Source (OPPIS).

In August 1987, a routine Ames test on soot from the Lawrence Livermore National Laboratory (LLNL) 4-in. gun showed that the soot was mutagenic to Salmonella bacteria. Subsequent liquid chromatography on the soot showed that, out of hundreds of ultravoilet-absorbing compounds found in the residue, only three or four were mutagenic. When a sample large enough to weigh was collected, it was found that No environmentally identified complex mixture has ever been reported with as much Ames/Salmonella activity per gram as the gun residues.'' Since then, Ames tests of hundreds of samples have verified that the residues from our gun tanks may be hazardous to health. The actual degree of the hazard and the identity of the offending chemicals are still unknown. 2 refs.