The development in the 1950's and 60's of crossed molecular beam methods for studying chemical reactions at the single-collision molecular level stimulated the need and desire for theoretical methods to describe these and other dynamical processes in molecular systems. Chemical dynamics theory has made great strides in the ensuing decades, so that methods are now available for treating the quantum dynamics of small molecular systems essentially completely. For the large molecular systems that are of so much interest nowadays (e.g. chemical reactions in solution, in clusters, in nano-structures, in biological systems, etc.), however, the only generally available theoretical approach is classical molecular dynamics (MD) simulations. Much effort is currently being devoted to the development of approaches for describing the quantum dynamics of these complex systems. This paper reviews some of these approaches, especially the use of semiclassical approximations for adding quantum effects to classical MD simulations, also showing some new versions that should make these semiclassical approaches even more practical and accurate.

We report the experimental confirmation of the production of element 110. In the bombardment of a {sup 208}Pb target with a 309 MeV {sup 64}Ni beam, we have observed two chains of time- and position-correlated events. Each chain consisted of the implantation of an evaporation residue followed by the emission of {alpha}-particles. We attribute these two chains to the decay of {sup 271}110 produced with a cross section of 8.3{sup +11}{sub -5.3} pb.

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Isotope tracer studies, particularly radiocarbon measurements, play a key role in biological, nutritional, and environmental research. Accelerator mass spectrometry (AMS) is now the most sensitive detection method for radiocarbon, but AMS is not widely used in kinetic studies of humans. Part of the reason is the expense, but costs would decrease if AMS were used more widely. One component in the cost is sample preparation for AMS. Biological and environmental samples are commonly reduced to graphite before they are analyzed by AMS. Improvements and mechanization of this multi-step procedure is slowed by a lack of organized educational materials for AMS sample preparation that would allow new investigators to work with the technique without a substantial outlay of time and effort. We present a detailed sample preparation protocol for graphitizing biological samples for AMS and include examples of nutrition studies that have used this procedure.

A gamma-ray survey and analysis of sixteen riverbed samples from the Reedy River watershed near Simpsonville, SC were conducted and compared with national and international studies of primordial radionuclides. The study reported here follows on a recent discovery of anomalously high uranium concentrations in several private well waters in the area near Simpsonville, SC. A HPGe spectrometer was used for quantification of gamma emitting radionuclides in the sediments. All sediments contained radionuclides from the uranium and thorium series as well as {sup 40}K. Uranium-238 concentrations in sediment samples ranged from 11.1 to 74.2 Bq kg{sup -1}. The measured radionuclide concentrations were compared with data from UNSCEAR and NURE reports. The river and stream sediment data were augmented by in situ NaI(Tl) gamma-ray spectrometer measurements. Comparisons between the ex-situ and in-situ measurements indicate equivalently distributed uranium in the surface soils and stream sediments, the source of which is likely attributed to the monazite belts that are known to exist in the area.

The attached pictures are examples of shielding models used by WSMS. The models were used in shielding evaluations for Tank 50 pump replacement. They show the relative location of shielding to radiation sources for pumps and pipes. None of the calculations that were associated with these models involved UCNI. The last page contains two pictures from a shielding calculation for the saltstone area. The upper picture is a conceptual drawing. The lower picture is an image copied from the website of a supplier for the project.

Wireless communication is ineffective for communicating through a solid steel wall due to the shielding effect of the metal. In some cases, holes can be made in the wall to allow wires to pass through, enabling the transport of electronic data. However, holes are often undesirable because they can reduce the integrity of the wall. This paper describes several approaches for using ultrasound to communicate low-rate digital data through a steel wall. The techniques minimize the complexity and power consumption of the communications hardware on the side of the wall from which the data is being sent, supporting applications in which a sensor may be either permanently embedded in a structure or is difficult to reach for servicing. Both pulsed and continuous-wave ultrasound techniques are described. Experimental data is presented showing the performance of the techniques when implemented using 1 MHz transducers mounted on a 15.24 cm (6 inch) thick steel wall. The results show that data rates on the order of 500 bits per second are readily available using simple communications techniques. Higher rates are possible if equalization is used to mitigate the effects of the multipath propagation within the steel block.

We describe a simple model for electron-molecule collisions that has one nuclear and one electronic degree of freedom and that can be solved to arbitrarily high precision, without making the Born-Oppenheimer approximation, by employing a combination of the exterior complex scaling method and a finite-element implementation of the discrete variable representation. We compare exact cross sections for vibrational excitation and dissociative attachment with results obtained using the local complex potential approximation as commonly applied in the ''boomerang'' model, and suggest how this two-dimensional model can be used to test the underpinnings of contemporary nonlocal approximations to resonant collisions.

The BABAR Silicon Vertex Tracker (SVT) has been efficiently operated for six years since the start of data taking in 1999. Due to higher than expected background levels some unforeseen effects have appeared. We discuss: a shift in the pedestal for the channels of the AToM readout chips that are most exposed to radiation; an anomalous increase in the bias leakage current for the modules in the outer layers. Estimates of future radiation doses and occupancies are shown together with the extrapolated detector performance and lifetime, in light of the new observations.