None

N/A

None

N/A

None

N/A

None

None

Cs is one of the more problematic fission product radionuclides to immobilize due to its high volatility at elevated temperatures, ability to form water soluble compounds, and its mobility in many host materials. The hollandite structure is a promising crystalline host for Cs immobilization and has been traditionally fabricated by solid state sintering methods. This study presents the structure and performance of Ba{sub 1.0}Cs{sub 0.3}A{sub 2.3}Ti{sub 5.7}O{sub 16}; A = Cr, Fe, Al hollandite fabricated by melt processing. Melt processing is considered advantageous given that melters are currently in use for High Level Waste (HLW) vitrification in several countries. This work details the impact of Cr additions that were demonstrated to i) promote the formation of a Cs containing hollandite phase and ii) maintain the stability of the hollandite phase in reducing conditions anticipated for multiphase waste form processing.

N/A

None

None

None

N/A

None

N/A

N/A

We investigate tunable plasmon resonant cavity arrays in paired parallel nanowire waveguides. Resonances are observed when the waveguide length is an odd multiple of quarter plasmon wavelengths, consistent with boundary conditions of node and antinode at the ends. Two nanowire waveguides satisfy the dispersion relation of a planar metal-dielectric-metal waveguide of equivalent width equal to the square field average weighted gap. Confinement factors over 103 are possible due to plasmon focusing in the inter-wire space.

We present a detailed description of the Voronoi Tessellation (VT) cluster finder algorithm in 2+1 dimensions, which improves on past implementations of this technique. The need for cluster finder algorithms able to produce reliable cluster catalogs up to redshift 1 or beyond and down to 10{sup 13.5} solar masses is paramount especially in light of upcoming surveys aiming at cosmological constraints from galaxy cluster number counts. We build the VT in photometric redshift shells and use the two-point correlation function of the galaxies in the field to both determine the density threshold for detection of cluster candidates and to establish their significance. This allows us to detect clusters in a self-consistent way without any assumptions about their astrophysical properties. We apply the VT to mock catalogs which extend to redshift 1.4 reproducing the ?CDM cosmology and the clustering properties observed in the Sloan Digital Sky Survey data. An objective estimate of the cluster selection function in terms of the completeness and purity as a function of mass and redshift is as important as having a reliable cluster finder. We measure these quantities by matching the VT cluster catalog with the mock truth table. We show that the VT can produce …

None

The ATF2 facility at KEK is a proving ground for linear collider technology with a well instrumented extracted beam line and Final Focus (FF). The primary ATF2 goal is to demonstrate the extreme beam demagnification and spot stability needed for a linear collider FF. But the ATF2 FF uses water cooled magnets and the ILC baseline has a superconducting (SC) FF. We plan to upgrade ATF2 and replace some of the warm FF magnets with SC FF magnets. The ATF2 SC magnets, like the ILC FF, will made via direct wind construction. ATF2 coil winding is in progress at BNL and warm magnetic measurements indicate we have achieved good field quality. Studies indicate that having ATF2 FF magnets with larger aperture and better field quality should allow reducing the ATF2 FF beta function for study of focusing regimes relevant to CLIC. The ATF2 magnet cryostat will have laser view ports for directly monitoring cold mass movement. We plan to make stability measurements at BNL and KEK to relate ATF2 FF magnet performance to that of a full length ILC QD0 R and D FF prototype under construction at BNL.

We describe the data analysis procedures for an emerging interferometric technique for measuring motion across a two-dimensional image at a moment in time, i.e. a snapshot 2d-VISAR. Velocity interferometers (VISAR) measuring target motion to high precision have been an important diagnostic in shockwave physics for many years Until recently, this diagnostic has been limited to measuring motion at points or lines across a target. We introduce an emerging interferometric technique for measuring motion across a two-dimensional image, which could be called a snapshot 2d-VISAR. If a sufficiently fast movie camera technology existed, it could be placed behind a traditional VISAR optical system and record a 2d image vs time. But since that technology is not yet available, we use a CCD detector to record a single 2d image, with the pulsed nature of the illumination providing the time resolution. Consequently, since we are using pulsed illumination having a coherence length shorter than the VISAR interferometer delay ({approx}0.1 ns), we must use the white light velocimetry configuration to produce fringes with significant visibility. In this scheme, two interferometers (illuminating, detecting) having nearly identical delays are used in series, with one before the target and one after. This produces fringes with at …

Cadmium Zinc Telluride (CdZnTe or CZT) is a very attractive material for room-temperature semiconductor detectors because of its wide band-gap and high atomic number. Despite these advantages, CZT still presents some material limitations and poor hole mobility. In the past decade most of the developing CZT detectors focused on designing different electrode configurations, mainly to minimize the deleterious effect due to the poor hole mobility. A few different electrode geometries were designed and fabricated, such as pixelated anodes and Frisch-grid detectors developed at Brookhaven National Lab (BNL). However, crystal defects in CZT materials still limit the yield of detector-grade crystals, and, in general, dominate the detector's performance. In the past few years, our group's research extended to characterizing the CZT materials at the micro-scale, and to correlating crystal defects with the detector's performance. We built a set of unique tools for this purpose, including infrared (IR) transmission microscopy, X-ray micro-scale mapping using synchrotron light source, X-ray transmission- and reflection-topography, current deep level transient spectroscopy (I-DLTS), and photoluminescence measurements. Our most recent work on CZT detectors was directed towards detailing various crystal defects, studying the internal electrical field, and delineating the effects of thermal annealing on improving the material properties. In …

Thick-shell CdSe/nCdS (n {ge} 10) nanocrystals were recently reported that show remarkably suppressed fluorescence intermittency or 'blinking' at the single-particle level as well as slow rates of Auger decay. Unfortunately, whereas CdSe/nCdS nanocrystal synthesis is well-developed up to n {le} 6 CdS monolayers (MLs), reproducible syntheses for n {ge} 10 MLs are less understood. Known procedures sometimes result in homogeneous CdS nucleation instead of heterogeneous, epitaxial CdS nucleation on CdSe, leading to broad and multimodal particle size distributions. Critically, obtained core/shell sizes are often below those desired. This article describes synthetic conditions specific to thick-shell growth (n {ge} 10 and n {ge} 20 MLs) on both small (sub2 nm) and large (>4.5 nm) CdSe cores. We find added secondary amine and low concentration of CdSe cores and molecular precursors give desired core/shell sizes. Amine-induced, partial etching of CdSe cores results in apparent shell-thicknesses slightly beyond those desired, especially for very-thick shells (n {ge} 20 MLs). Thermal ripening and fast precursor injection lead to undesired homogeneous CdS nucleation and incomplete shell growth. Core/shells derived from small CdSe (1.9 nm) have longer PL lifetimes and more pronounced blinking at single-particle level compared with those derived from large CdSe (4.7 nm). We expect …