Various internal defects, such as Te inclusions, twin boundaries, dislocation, etc., are prevalent in as-grown CdZnTe (CZT) crystals, which affect the charge transport properties of CZT crystals and, therefore, worsen the performance of CZT detectors. In order to develop high quality CZT detectors, it is imperative to clarify the effects of internal defects on the charge transport properties of CZT. Simple flood illumination with nuclear radiation source cannot reveal the nature of highly localized defects in CZT. Therefore, at Brookhaven's National Synchrotron Light Source (NSLS), we have developed a unique testing system for micro-scale defect investigation of CZT, which employs an X-ray beam collimated with the spatial resolution as small as 3 x 3 {micro}m{sup 2}, a microscopic size comparable to the scale of common defects in CZT. This powerful tool enables us to investigate the effect of internal defects on charge transport properties of CZT in detail.

By the end of August, 2005, the Russia Federation delivered to the United States (U.S.) more than 7,000 metric tons (MT) of low enriched uranium (LEU) containing approximately 46 million SWU and 75,000 MT of natural uranium. This uranium was blended down from weapons-grade (nominally enriched to 90% {sup 235}U) highly enriched uranium (HEU) under the 1993 HEU Purchase Agreement that provides for the blend down of 500 MT HEU into LEU for use as fuel in commercial nuclear reactors. The HEU Transparency Program, under the National Nuclear Security Administration (NNSA), monitored the conversion and blending of the more than 250 MT HEU used to produce this LEU. The HEU represents more than half of the 500 MT HEU scheduled to be blended down through the year 2013 and is equivalent to the elimination of more than 10,000 nuclear devices. The HEU Transparency Program has made considerable progress in its mission to develop and implement transparency measures necessary to assure that Russian HEU extracted from dismantled Russian nuclear weapons is blended down into LEU for delivery to the United States. U.S. monitor observations include the inventory of in process containers, observation of plant operations, nondestructive assay measurements to determine {sup …

We consider that semi-insulating (Cd,Mn)Te crystals may well successfully replace the commonly used (Cd,Zn)Te crystals as a material for manufacturing large-area X- and gamma-ray detectors. The Bridgman growth method yields good quality and high-resistivity (10{sup 9}-10{sup 10} {Omega}-cm) crystals of (Cd,Mn)Te:V. Doping with vanadium ({approx} 10{sup 16} cm{sup -3}), which acts as a compensating agent, and annealing in cadmium vapors, which reduces the number of cadmium vacancies in the as-grown crystal, ensure this high resistivity. Detector applications of the crystals require satisfactory electrical contacts. Hence, we explored techniques of ensuring good electrical contacts to semi-insulating (Cd,Mn)Te crystals. Our findings are reported here. Before depositing the contact layers, we prepared an 'epi-ready' surface of the crystal platelet by a procedure described earlier for various tellurium-based II-VI compound crystals. A molecular beam epitaxy (MBE) apparatus was used to deposit various types of contact layers: Monocrystalline semiconductor layers, amorphous- and nanocrystalline semiconductor layers, and metal layers were studied. We employed ZnTe heavily doped ({approx} 10{sup 18} cm{sup -3}) with Sb, and CdTe heavily doped ({approx} 10{sup 17} cm{sup -3}) with In as the semiconductors to create contact layers that subsequently enable good contact (with a narrow, tunneling barrier) to the Au layer that …

Solving Schroedinger equation in quantum mechanics presents a challenging task in numerical methods due to the high order behavior and high dimension characteristics in the wave functions, in addition to the highly coupled nature between wave functions. This work introduces orbital and polynomial enrichment functions to the partition of unity for solution of Schroedinger equation under the framework of HP-Clouds. An intrinsic enrichment of orbital function and extrinsic enrichment of monomial functions are proposed. Due to the employment of higher order basis functions, a higher order stabilized conforming nodal integration is developed. The proposed methods are implemented using the density functional theory for solution of Schroedinger equation. Analysis of several single and multi-electron/nucleus structures demonstrates the effectiveness of the proposed method.

A new method that combines staggered grid Arbitrary Lagrangian-Eulerian (ALE) techniques with structured local adaptive mesh refinement (AMR) has been developed for solution of the Euler equations. The novel components of the combined ALE-AMR method hinge upon the integration of traditional AMR techniques with both staggered grid Lagrangian operators as well as elliptic relaxation operators on moving, deforming mesh hierarchies. Numerical examples demonstrate the utility of the method in performing detailed three-dimensional shock-driven instability calculations.

The 1 m long Nb{sub 3}Sn dipole magnet HD2, fabricated and tested at Lawrence Berkeley National Laboratory, represents a step towards the development of block-type accelerator quality magnets operating in the range of 13-15 T. The magnet design features two coil modules composed of two layers wound around a titanium-alloy pole. The layer 1 pole includes a round cutout to provide room for a bore tube with a clear aperture of 36 mm. After a first series of tests where HD2 reached a maximum bore field of 13.8 T, corresponding to an estimated peak field on the conductor of 14.5 T, the magnet was disassembled and reloaded without the bore tube and with a clear aperture increased to 43 mm. We describe in this paper the magnet training observed in two consecutive tests after the removal of the bore tube, with a comparison of the quench performance with respect to the previous tests. An analysis of the voltage signals recorded before and after training quenches is then presented and discussed, and the results of coil visual inspections reported.

A high field Nb{sub 3}Al common coil magnet is under development as an R&D of 'Advanced Superconducting Magnets for the LHC Luminosity Upgrade', in the framework of the CERN-KEK cooperation program. The goal of this research is to demonstrate the feasibility of high field magnet wound with Nb{sub 3}Al cable. The common coil approach and the shell-based structure were adopted in the design of this magnet. Besides three Nb{sub 3}Al coils, two Nb{sub 3}Sn coils were included to increase the peak field of the whole magnet. The two types of coils were designed with different straight lengths to reduce the peak field of the Nb{sub 3}Sn coils. The peak fields of the Nb{sub 3}Al and Nb{sub 3}Sn coils are 13.1 T and 11.8 T respectively. An aluminum shell together with four aluminum rods applies stress to the coils to overcome the Lorenz force during excitation. Two different support structures for the superconducting coils were introduced in this paper. The development status is also presented.

The threat of nuclear terrorism has become a global concern. Many countries continue to make efforts to strengthen nuclear security by enhancing systems of nuclear material protection, control, and accounting (MPC&A). Though MPC&A systems can significantly upgrade nuclear security, they do not eliminate the "human factor." Gen. Eugene Habiger, a former "Assistant Secretary for Safeguards and Security" at the U.S. Department of Energy’s (DOE) nuclear-weapons complex and a former commander of U.S. strategic nuclear forces, has observed that "good security is 20% equipment and 80% people." Although eliminating the "human factor" is not possible, accounting for and mitigating the risk of the insider threat is an essential element in establishing an effective nuclear security culture. This paper will consider the organizational role in mitigating the risk associated with the malicious insider through monitoring and enhancing human reliability and motivation as well as enhancing the nuclear security culture.

Recent TEM studies of deformation substructures developed in tantalum and tantalum-tungsten alloys shock-deformed at a peak pressure {approx}45 GPa have revealed the occurrence of shock-induced phase transformation [i.e., {alpha} (bcc) {yields} {omega} (hexagonal) transition] in addition to shock-induced deformation twinning. The volume fraction of twin and {omega} domains increases with increasing content of tungsten. A controversy arises since tantalum exhibits no clear equilibrium solid-state phase transformation under hydrostatic pressures up to 174 GPa. It is known that phase stability of a material system under different temperatures and pressures is determined by system free energy. That is, a structural phase that has the lowest free energy will be stable. For pressure-induced phase transformation under hydrostatic-pressure conditions, tantalum may undergo phase transition when the free energy of a competing phase {omega} becomes smaller than that of the parent phase {alpha} above a critical pressure (P{sub eq}), i.e., the equilibrium {alpha} {yields} {omega} transition occurs when the pressure increases above P{sub eq}. However, it is also known that material shocked under dynamic pressure can lead to a considerable increase in temperature, and the higher the applied pressure the higher the overheat temperature. This means a higher pressure is required to achieve an equivalent …

A new two-dimensional thermal neutron detector concept that is capable of very high rates is being developed. It is based on neutron conversion in {sup 3}He in an ionization chamber (unity gas gain) that uses only a cathode and anode plane; there is no additional electrode such as a Frisch grid. The cathode is simply the entrance window, and the anode plane is composed of discrete pads, each with their own readout electronics implemented via application specific integrated circuits. The aim is to provide a new generation of detectors with key characteristics that are superior to existing techniques, such as higher count rate capability, better stability, lower sensitivity to background radiation, and more flexible geometries. Such capabilities will improve the performance of neutron scattering instruments at major neutron user facilities. In this paper, we report on progress with the development of a prototype device that has 48 x 48 anode pads and a sensitive area of 24cm x 24cm.

Liquid waste generated by the PUREX process for separation of nuclear materials is concentrated and stored in Type IV single-shell carbon steel tanks at the Savannah River Site (SRS). The Type IV tanks for this waste do not have cooling coils and have not undergone heat treatment to stress-relieve the tanks. After the waste is concentrated by evaporation, it becomes very alkaline and can cause stress corrosion cracking (SCC) and pitting corrosion of the tank materials. SRS has experienced leakage from non-stress-relieved waste tanks constructed of A285 carbon steel and pitting of A212 carbon steel tanks in the vapor space. An investigation of tank materials has been undertaken at SRS to develop a basic understanding of caustic SCC of A285 and A212 grade carbon steels exposed to aqueous solutions, primarily containing sodium hydroxide (NaOH), sodium nitrate (NaNO{sub 3}), and sodium nitrite (NaNO{sub 2}) at temperatures relevant to the operating conditions of both the F and H area plants. This report presents the results of this corrosion testing program. Electrochemical tests were designed using unstressed coupons in a simulated tank environment. The purpose of this testing was to determine the corrosion susceptibility of the tank materials as a function of chemical …

Momentum imaging experiments on dissociative electron attachment to the water molecule are combined with ab initio theoretical calculations of the angular dependence of the quantum mechanical amplitude for electron attachment to provide a detailed picture of the molecular dynamics of dissociation attachment via the two lowest energy Feshbach resonances. The combination of momentum imaging experiments and theory can reveal dissociation dynamics for which the axial recoil approximation breaks down and thus provides a powerful reaction microscope for DEA to polyatomics.

The ideal operation of CdZnTe devices entails having a uniformly distributed internal electric field. Such uniformity especially is critical for thick long-drift-length detectors, such as large-volume CPG and 3-D multi-pixel devices. Using a high-spatial resolution X-ray mapping technique, we investigated the distribution of the electric field in real devices. Our measurements demonstrate that in thin detectors, <5 mm, the electric field-lines tend to bend away from the side surfaces (i.e., a focusing effect). In thick detectors, >1 cm, with a large aspect ratio (thickness-to-width ratio), we observed two effects: the electric field lines bending away from or towards the side surfaces, which we called, respectively, the focusing field-line distribution and the defocusing field-line distribution. In addition to these large-scale variations, the field-line distributions were locally perturbed by the presence of extended defects and residual strains existing inside the crystals. We present our data clearly demonstrating the non-uniformity of the internal electric field.

Muon Colliders need intense, very short, proton bunches. The requirements are presented and a number of possible bunching systems discussed. The best solution uses a small super-conducting buncher ring with 6 bunches that are taken though separate transports and combined on the target.

We present our measurements of (Cd,Mn)Te photoconductive detectors (PCDs), fabricated for the goal of measuring both the temporal and spectral dependences of X-ray emissions generated from laser-illuminated targets during the inertial confinement fusion experiments. Our Cd{sub 1-x}Mn{sub x}Te (x = 0.05) single crystals, doped with V, were grown using a vertical Bridgman method and, subsequently, annealed in Cd for the highest resistivity ({approx}10{sup 10} {Omega}cm) and a good mobility-lifetime product ({approx}10{sup -3} cm{sup 2}/V). The 1-mm- and 2.3-mm-thick detectors were placed in the same housing as two 1-mm-thick diamond PCDs. All devices were pre-screened by a 7.6-mm-thick Be X-ray filter with a frequency cutoff of 1 keV. The incident shots from the OMEGA laser were 1-ns-long square pulses with energies ranging from 2.3 kJ to 22.6 kJ, and the PCDs were biased with 5000 V/cm. The response amplitudes and rise times of our (Cd,Mn)Te PCDs were comparable with the diamond detector performance, while the decay times were 4 to 10 times longer and in the 2-5 ns range. We observed two X-ray emission events separated by 1.24 ns. The first was identified as caused by heating of the target and creating a hot corona, while the second one was from …

Researchers at the Savannah River National Laboratory (SRNL) examined the stability of Dow Corning Q2-3183A antifoam to radiation and aqueous hydroxide solutions. Initial foam control studies with Hanford tank waste showed the antifoam reduced foaming. The antifoam was further tested using simulated Hanford tank waste spiked with antifoam that was heated and irradiated (2.1 x 10{sup 4} rad/h) at conditions (90 C, 3 M NaOH, 8 h) expected in the processing of radioactive waste through the Waste Treatment and Immobilization Plant (WTP) at Hanford. After irradiation, the concentration of the major polymer components polydimethylsiloxane (PDMS) and polypropylene glycol (PPG) in the antifoam was determined by gel permeation chromatography (GPC). No loss of the major polymer components was observed after 24 h and only 15 wt% loss of PDMS was reported after 48 h. The presence of degradation products were not observed by gas chromatography (GC), gas chromatography mass spectrometry (GCMS) or high performance liquid chromatography mass spectrometry (HPLC-MS). G values were calculated from the GPC analysis and tabulated. The findings indicate the antifoam is stable for 24 h after exposure to gamma radiation, heat, and alkaline simulated waste.

We suggest that (Cd,Mn)Te is a suitable material for fabricating gamma- and X-ray detectors. Our investigations, reported here, are focused on producing high-quality (Cd,Mn)Te crystals with high resistivity (10{sup 9} {Omega}-cm) by the Bridgman method. As-grown, undoped (Cd,Mn)Te crystals are typically p-type, signifying that they contain excess Cd vacancies (acting as acceptors), accumulated during growth. Doping with vanadium atoms, which function as compensating centers, results in a semi-insulating material (Cd,Mn)Te:V. Properly annealing the platelets in cadmium vapors at uniform temperature reduces the number of cadmium vacancies, and lowers the level of the vanadium doping required for compensation. We found that annealing in cadmium vapors not only decreases the concentration of the native cadmium vacancies but also improves the crystal's quality. Infrared observations of the interior of the samples show that annealing in a temperature gradient perpendicular to the platelet has an additional effect, viz., the tellurium precipitates migrate towards the side where the temperature is higher. We demonstrate, with IR pictures of monocrystalline (Cd,Mn)Te:V platelets cut parallel to the (111) crystal planes, the influence on tellurium inclusions and precipitates of various conditions of annealing in cadmium vapors.

Te inclusions existing at high concentrations in CdZnTe (CZT) material can degrade the performance of CZT detectors. These microscopic defects trap the free electrons generated by incident radiation, so entailing significant fluctuations in the total collected charge and thereby strongly affecting the energy resolution of thick (long-drift) detectors. Such effects were demonstrated in thin planar detectors, and, in many cases, they proved to be the dominant cause of the low performance of thick detectors, wherein the fluctuations in the charge losses accumulate along the charge's drift path. We continued studying this effect using different tools and techniques. We employed a dedicated beamline recently established at BNL's National Synchrotron Light Source for characterizing semiconductor radiation detectors, along with an IR transmission microscope system, the combination of which allowed us to correlate the concentration of defects with the devices performances. We present here our new results from testing over 50 CZT samples grown by different techniques. Our goals are to establish tolerable limits on the size and concentrations of these detrimental Te inclusions in CZT material, and to provide feedback to crystal growers to reduce their numbers in the material.

An understanding of both the hydraulic properties of the aquifer and the depth distribution of salts is critical for evaluating the potential of groundwater for conjunctive water use and for maintaining suitable groundwater quality in agricultural regions where groundwater is used extensively for irrigation and drinking water. The electrical conductivity profiles recorded in a well using the flowing fluid electric conductivity logging (FEC logging) method can be analyzed to estimate interval specific hydraulic conductivity and estimates of the salinity concentration with depth. However, irrigation wells that are common in agricultural regions have limited access into them because these wells are still in operation, and the traditional equipment used for FEC logging cannot fit through the small access pipe intersecting the well. A modified, miniaturized FEC logging technique was developed such that this logging method could be used in wells with limited access. In addition, a new method for injecting water over the entire screened interval of the well was developed to reduce the time required to perform FEC logging. Results of FEC logging using the new methodology and miniaturized system in two irrigation wells are also summarized.

As part of the DEEP2 galaxy redshift survey, we analyze absorption line strengths in stacked Keck/DEIMOS spectra of red field galaxies with weak to no emission lines, at redshifts 0.7 {approx}< z {approx}< 1. Comparison with models of stellar population synthesis shows that red galaxies at z {approx} 0:9 have mean luminosity-weighted ages of the order of only 1 Gyr and at least solar metallicities. These ages cannot be reconciled with a scenario where all stars evolved passively after forming at very high z. Rather, a significant fraction of stars can be no more than 1 Gyr old, which means that some star formation in the stacked populations continued to at least z {approx} 1:2. Furthermore, a comparison of these distant galaxies with a local SDSS sample, using stellar populations synthesis models, shows that the drop in the equivalent width of H{delta} from z {approx} 0:9 to 0.1 is less than predicted by passively evolving models. This admits of two interpretations: either each individual galaxy experiences continuing low-level star formation, or the red-sequence galaxy population from z {approx} 0:9 to 0.1 is continually being added to by new galaxies with younger stars.

This paper demonstrates a method to determine thebidirectional transfer distribution function (BTDF) using an integratingsphere. Information about the sample's angle dependent scattering isobtained by making transmittance measurements with the sample atdifferent distances from the integrating sphere. Knowledge about theilluminated area of the sample and the geometry of the sphere port incombination with the measured data combines to an system of equationsthat includes the angle dependent transmittance. The resulting system ofequations is an ill-posed problem which rarely gives a physical solution.A solvable system is obtained by using Tikhonov regularization on theill-posed problem. The solution to this system can then be used to obtainthe BTDF. Four bulk-scattering samples were characterised using both twogoniophotometers and the described method to verify the validity of thenew method. The agreement shown is great for the more diffuse samples.The solution to the low-scattering samples contains unphysicaloscillations, butstill gives the correct shape of the solution. Theorigin of the oscillations and why they are more prominent inlow-scattering samples are discussed.

In support of Stockpile Stewardship activities, accelerated aging tests on a plutonium alloy enriched with 7.3 atomic percentage of {sup 238}Pu is underway using dilatometry at 35, 50, and 65 C and immersion density measurements of material stored at 50 C. Changes in density are expected from radiation damage in the lattice and helium in-growth. After twenty-five equivalent years of aging, the dilatometry data shows that the alloys at 35 C have expanded in volume by 0.11% to 0.12% and have started to exhibit a near linear expansion behavior primarily caused by the helium accumulation. The average He-to-vacancy ratio from tested specimens was determined to be around 2.3. The model for the lattice damage and helium in-growth accurately represents the volume swelling at 35 C. The density converted from the dilatometry corresponds well to the decreasing density trend of reference plutonium alloys as a function of time.

Washington Savannah River Company (WSRC) operates the Savannah River Site (SRS) in Aiken, SC under contract with the U.S. Department of Energy (DOE). SRS had the need to ship 227 drums of low enriched uranium oxide (LEUO) to a disposal site. The LEUO had been packaged nearly 25 years ago in U.S. Department of Transportation (DOT) 17C 55-gallon drums and stored in a warehouse. Since the 235U enrichment was just above 1 percent by weight (wt%) the material did not qualify for the fissile material exceptions in 49 CFR 173.453, and therefore was categorized as 'fissile material' for shipping purposes. WSRC evaluated all existing Type AF packages and did not identify any feasible packaging. Applying for a new Type AF certificate of compliance was considered too costly for a one-time/one-way shipment for disposal. Down-blending the material with depleted uranium (to reduce enrichment below 1 wt% and enable shipment as low specific activity (LSA) radioactive material) was considered, but appropriate blending facilities do not exist at SRS. After reviewing all options, WSRC concluded that seeking a DOT Special Permit was the best option to enable shipment of the material for permanent disposal. WSRC submitted the Special Permit application to the DOT, …

The DECOVALEX project is an international cooperative project initiated by SKI, the Swedish Nuclear Power Inspectorate, with participation of about 10 international organizations. The general goal of this project is to encourage multidisciplinary interactive and cooperative research on modeling coupled thermo-hydro-mechanical-chemical (THMC) processes in geologic formations in support of the performance assessment for underground storage of radioactive waste. One of the research tasks, initiated in 2004 by the U.S. Department of Energy (DOE), addresses the long-term impact of geomechanical and geochemical processes on the flow conditions near waste emplacement tunnels. Within this task, four international research teams conduct predictive analysis of the coupled processes in two generic repositories, using multiple approaches and different computer codes. Below, we give an overview of the research task and report its current status.