The preparation of ultra fine beryllium powder by the amalgam process Technical report

Beryllium powder production by electrolysis of beryllium chloride-sodium chloride molten eutectic mixtur

Nanopositioning of a diamond nanocrystal containing a single NV defect center

Precise control over the position of a single quantum object is important for many experiments in quantum science and nanotechnology. We report on a technique for high-accuracy positioning of individual diamond nanocrystals. The positioning is done with a home-built nanomanipulator under real-time scanning electron imaging, yielding an accuracy of a few nanometers. This technique is applied to pick up, move and position a single NV defect center contained in a diamond nanocrystal. We verify that the unique optical and spin properties of the NV center are conserved by the positioning process.Comment: 3 pages, 3 figures; high-resolution version available at http://www.ns.tudelft.nl/q

Ultra-fine beryllium powder by amalgam process Progress report, period ending 31 Oct. 1966

Metallurgical evaluation of beryllium powdered metal, and electron microscope studies of agglomerate particle size

Excitons in Electrostatic Traps

We consider in-plane electrostatic traps for indirect excitons in coupled quantum wells, where the traps are formed by a laterally modulated gate voltage. An intrinsic obstacle for exciton confinement in electrostatic traps is an in-plane electric field that can lead to exciton dissociation. We propose a design to suppress the in-plane electric field and, at the same time, to effectively confine excitons in the electrostatic traps. We present calculations for various classes of electrostatic traps and experimental proof of principle for trapping of indirect excitons in electrostatic traps.Comment: 4 pages, 3 figure

Spin dynamics in the optical cycle of single nitrogen-vacancy centres in diamond

We investigate spin-dependent decay and intersystem crossing in the optical cycle of single negatively-charged nitrogen-vacancy (NV) centres in diamond. We use spin control and pulsed optical excitation to extract both the spin-resolved lifetimes of the excited states and the degree of optically-induced spin polarization. By optically exciting the centre with a series of picosecond pulses, we determine the spin-flip probabilities per optical cycle, as well as the spin-dependent probability for intersystem crossing. This information, together with the indepedently measured decay rate of singlet population provides a full description of spin dynamics in the optical cycle of NV centres. The temperature dependence of the singlet population decay rate provides information on the number of singlet states involved in the optical cycle.Comment: 11 pages, 5 figure

Evaluation of the application of ERTS-1 data to the regional land use planning process

The author has identified the following significant results. Employing simple and economical extraction methods, ERTS can provide valuable data to the planners at the state or regional level with a frequency never before possible. Interactive computer methods of working directly with ERTS digital information show much promise for providing land use information at a more specific level, since the data format production rate of ERTS justifies improved methods of analysis

Probing dynamics of an electron-spin ensemble via a superconducting resonator

We study spin relaxation and diffusion in an electron-spin ensemble of nitrogen impurities in diamond at low temperature (0.25-1.2 K) and polarizing magnetic field (80-300 mT). Measurements exploit mode- and temperature-dependent coupling of hyperfine-split sub-ensembles to the resonator. Temperature-independent spin linewidth and relaxation time suggest that spin diffusion limits spin relaxation. Depolarization of one sub-ensemble by resonant pumping of another indicates fast cross-relaxation compared to spin diffusion, with implications on use of sub-ensembles as independent quantum memories.Comment: 5 pages, 5 figures, and Supplementary Information (2 figures

The Preliminary Archeological Inventory of the Savannah River Plant, Aiken and Barnwell Counties, South Carolina

Archeological investigations were conducted on the Savannah River Plant in Aiken and Barnwell Counties, South Carolina under contract with the United States Department of Energy by the Institute of Archeology and Anthropology, University of South Carolina. The purpose of the study was to perform a reconnaissance and prepare a preliminary inventory of archeological sites in the plant in order to provide land use planning information. During three 2.5 month field seasons, 309 discrete sites were located and recorded within the plant boundaries using an opportunistic sampling strategy which focused on disturbed and exposed ground surfaces in the 200,000 acre study area. Approximately 450 linear miles, representing only a small portion of the plant (less than 10%), were covered in the fieldwork. Results of the survey were primarily of three kinds. First, 3 site classes--those related to base settlements, large limited activity, and small limited activity functions--were determined. Second, 141 occupational components, spanning the Early Archaic through the Historic Periods, were recognized at 103 sites. Occupational density appears to have been greatest during the Woodland Period from 1000 B.C. to about A.D. 1000. The third research area involved an inspection of occupational variability within five environmental zones (Upland, Slope, Dry Terrace, Flooded Terrace and Floodplain) to describe changes in land use. No significant variation between time periods was recognized, indicating similar land use patterns relating to hunting and gathering. Highest site frequencies occurred in the Dry Terrace and Floodplain Zones, which suggests a focus of all major settlements in high potential resource zones. In general, the information in this report presents the largest site survey data base known for the Savannah River below the Fall Line and is therefore of importance to the local prehistory.https://scholarcommons.sc.edu/archanth_books/1146/thumbnail.jp

Path Integral Approach to Residual Gauge Fixing

In this paper we study the question of residual gauge fixing in the path integral approach for a general class of axial-type gauges including the light-cone gauge. We show that the two cases -- axial-type gauges and the light-cone gauge -- lead to very different structures for the explicit forms of the propagator. In the case of the axial-type gauges, fixing the residual symmetry determines the propagator of the theory completely. On the other hand, in the light-cone gauge there is still a prescription dependence even after fixing the residual gauge symmetry, which is related to the existence of an underlying global symmetry.Comment: revtex 13pages, slightly expanded discussion, version to be published in Physical Review