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We characterized samples cut from different locations in as-grown CdZnTe (CZT) ingots, using Automated Infrared (IR) Transmission Microscopy and White Beam X-ray Diffraction Topography (WBXDT), to locate and identify the extended defects in them. Our goal was to define the distribution of these defects throughout the entire ingot and their effects on detectors' performance as revealed by the pulse-height spectrum. We found the highest- and the lowest- concentration of Te inclusions, respectively, in the head and middle part of the ingot, which could serve as guidance in selecting samples. Crystals with high concentration of Te inclusions showed high leakage current and poor performance, because the accumulated charge loss around trapping centers associated with Te inclusions distorts the internal electric field, affects the carrier transport properties inside the crystal, and finally degrades the detector's performance. In addition, other extended defects revealed by the WBXDT measurements severely reduced the detector's performance, since they trap large numbers of electrons, leading to a low signal for the pulse-height spectrum, or none whatsoever. Finally, we fully correlated the detector's performance with our information on the extended defects gained from both the IR- and the WBXDT-measurements.

A toroidal vortex of liquid FLiBe (LiF + BeF2) is suggested for the blanket of a fusion reactor. Because this reactor chamber has no solid first wall, it might avoid many of the problems that accom...

Synchrotron-based microprobe techniques were used to obtain precise and systematic information about the size distribution, spatial distribution, shape, electrical activity, and chemical states of iron-rich impurity clusters in multicrystalline silicon materials used for cost-effective solar cells. These experimentally observed properties of iron-rich clusters allow one to derive conclusions about the origins of iron contamination, the mechanisms for incorporating large amounts of Fe into mc-Si, quantitative information about the distribution of Fe in mc-Si and the impacts of such contamination on solar cell performance. Two distinct groups of iron-rich clusters have been identified in both materials: (a) the occasional large (diameter greater than or equal to 1 mu-m) particles, either oxidized and/or present with multiple other metal species reminiscent of stainless steels or ceramics, which are believed to originate from a foreign source such as the growth surfaces, production equipment, or feedstock, and (b) the more numerous, homogeneously distributed, and smaller iron silicide precipitates (dia. less than or equal to 800 nm, often < 100 nm), originating from a variety of possible formation mechanisms involving atomically dissolved iron in the melt or in the crystal. It was found that iron silicide nanoprecipitates account for bulk Fe concentrations as high as 1014-15 cm-3 and can have a large negative impact on device performance because of their homogeneous distribution along structural defects. The large (dia. greater than or equal to 1 mu-m) particles, while containing elevated amounts of metals, are low in spatial density and thus deemed to have a low direct impact on device performance, although they may have a large indirect impact via the dissolution of Fe, thus assisting the formation of iron silicide nanoprecipitates. These results demonstrate that it is not necessarily the total Fe content that limits mc-Si device performance, but the distribution of Fe within the material.

In this study, synchrotron-based x-ray absorption microspectroscopy (μ-XAS) is applied to identify the chemical states of copper-rich clusters within a variety of silicon materials, including as-grown cast multicrystalline silicon solar cell material with high oxygen concentration and other silicon materials with varying degrees of oxygen concentration and copper contamination pathways. In all samples, copper silicide (Cu3Si) is the only phase of copper identified. It is noted from thermodynamic considerations that unlike certain metal species, copper tends to form a silicide and not an oxidized compound because of the strong silicon–oxygen bonding energy; consequently the likelihood of encountering an oxidized copper particle in silicon is small, in agreement with experimental data. In light of these results, the effectiveness of aluminum gettering for the removal of copper from bulk silicon is quantified via x-ray fluorescence microscopy, and a segregation coefficient is determined from experimental data to be at least (1–2)×103. Additionally, μ-XAS data directly demonstrate that the segregation mechanism of Cu in Al is the higher solubility of Cu in the liquid phase. In light of these results, possible limitations for the complete removal of Cu from bulk mc-Si are discussed.

Abstract Newly accessible shale deposits and other unconventional sources of natural gas have dramatically increased global gas reserves and are regarded as major future energy sources. Shale gas drilling began in Texas and is expanding throughout the U.S. and globally. In Texas and other regions, large population centers overlie these deposits. As a result, city residents increasingly come into contact with extraction activities. The proximity of drilling activities to residential areas raises a number of concerns, including noise, dust and emissions hazards, public safety, diminished quality of life, and effects on neighborhood aesthetics and property values. Cities in Texas address these concerns through setback ordinances that regulate the distance between gas wells and residences, schools, floodplains, etc. Although the state of Texas permits drilling 200 ft (61 m) from residences, many municipalities in the Dallas–Fort Worth Metroplex (DFW) have established longer setback distances. This paper analyzes the purpose and basis for setback distances among 26 municipalities in DFW. Findings show that there is no uniform setback distance, distances have increased over time, and, rather than technically-based, setbacks are political compromises. For policy makers confronted with urban shale gas drilling, deriving setback distances from advanced emissions monitoring could decrease setback distance ambiguity.

Max Tech and Beyond: Fluorescent Lamps Project Managers Louis-Benoit Desroches & Karina Garbesi Environmental Energy Technologies Division Author Michael Scholand N14 Energy Limited, Navigant Consulting Inc. Lawrence Berkeley National Laboratory One Cyclotron Road Berkeley, CA 94720 April 1, 2012 The work described in this report was funded by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy, Building Technologies Program under Contract No. DE-AC02-05CH11231.

An intense charged particle beam with directed kinetic energy (γ_{b}-1)m_{b}c^{2} propagates in the z direction through an applied focusing field with transverse focusing force modeled by F_{foc}=-γ_{b}m_{b}ω_{β⊥}^{2}x_{⊥} in the smooth-focusing approximation. This paper examines properties of the axisymmetric, truncated thermal equilibrium distribution F_{b}(r,p_{⊥})=Aexp⁡(-H_{⊥}/T[over ^]_{⊥b})⊕(H_{⊥}-E_{b}), where A, T[over ^]_{⊥b}, and E_{b} are positive constants, and H_{⊥} is the Hamiltonian for transverse particle motion. The equilibrium profiles for beam number density, n_{b}(r)=∫d^{2}pF_{b}(r,p_{⊥}), and transverse temperature, T_{⊥b}(r)=[n_{b}(r)]^{-1}∫d^{2}p(p_{⊥}^{2}/2γ_{b}m_{b})F_{b}(r,p_{⊥}), are calculated self-consistently including space-charge effects. Several properties of the equilibrium profiles are noteworthy. For example, the beam has a sharp outer edge radius r_{b} with n_{b}(r≥r_{b})=0, where r_{b} depends on the value of E_{b}/T[over ^]_{⊥b}. In addition, unlike the choice of a semi-Gaussian distribution, F_{b}^{SG}=Aexp⁡(-p_{⊥}^{2}/2γ_{b}m_{b}T[over ^]_{⊥b})⊕(r-r_{b}), the truncated thermal equilibrium distribution F_{b}(r,p) depends on (r,p) only through the single-particle constant of the motion H_{⊥} and is therefore a true steady-state solution (∂/∂t=0) of the nonlinear Vlasov-Maxwell equations.

We describe a Monte Carlo solution for time dependent photon transport, in the difference formulation with the material in local thermodynamic equilibrium, that is piecewise linear in its treatment of the material state variable. Our method employs a Galerkin solution for the material energy equation while using Symbolic Implicit Monte Carlo to solve the transport equation. In constructing the scheme, one has the freedom to choose between expanding the material temperature, or the equivalent black body radiation energy density at the material temperature, in terms of finite element basis functions. The former provides a linear treatment of the material energy while the latter provides a linear treatment of the radiative coupling between zones. Subject to the conditional use of a lumped material energy in the vicinity of strong gradients, possible with a linear treatment of the material energy, our approach provides a robust solution for time dependent transport of thermally emitted radiation that can address a wide range of problems. It produces accurate results in thick media.