High rate production of polarized 3He with meta-stability exchange method

Keywords: polarized 3He, meta-stability exchange, infrared laserComment: 4 figures, submitted to J. Phys. Soc. Jpn

Spin Excitations in a Fermi Gas of Atoms

We have experimentally investigated a spin excitation in a quantum degenerate Fermi gas of atoms. In the hydrodynamic regime the damping time of the collective excitation is used to probe the quantum behavior of the gas. At temperatures below the Fermi temperature we measure up to a factor of 2 reduction in the excitation damping time. In addition we observe a strong excitation energy dependence for this quantum statistical effect.Comment: 4 pages, 3 figure

Causality and the speed of sound

A usual causal requirement on a viable theory of matter is that the speed of sound be at most the speed of light. In view of various recent papers querying this limit, the question is revisited here. We point to various issues confronting theories that violate the usual constraint.Comment: v2: additional discussion on models that appear to have superluminal signal speeds; version to appear in GR

The technology of ICRF systems

The technology of ICRF systems has made substantial gains in the past few years. The total power levels have increased from the 5-MW level to greater than 20 MW; the pulse lengths have increased from the 100-msec level to 30 seconds. Recently, fast wave current drive (FWCD) has been demonstrated using phased arrays of ICRF antennas. In order to achieve such large gains, substantial changes and improvements were needed in the level of design analysis, fabrication techniques, and system controls

Solvent extraction studies of coprocessing flowsheets: Results from Campaign 6 of the Solvent Extraction Test Facility (SETF)

A series of five solvent extraction tests were made in the Solvent Extraction Test Facility (SETF) during Campaign 6. Each test used a coprocessing flowsheet that included coextraction-coscrubbing of the heavy metals followed by partial partitioning of the uranium and plutonium into separate uranium and uranium-plutonium products. The separation of the uranium and plutonium was aided by the addition of HNO{sub 2} to the organic backscrub stream. Two of these tests compared the performance of the traditional Purex solvent, tri-n-butyl phosphate (TBP), with a potential replacement, tri-2-ethylhexyl phosphate (TEHP). The remaining three tests were made with a chemically-degraded TBP solvent to compare the effectiveness of two solvent cleanup methods - treatment with silica gel or scrubbing with sodium carbonate and water

Solvent extraction studies of coprocessing flowsheets: results from Campaign 5 of the Solvent Extraction Test Facility (SETF)

In Campaign 5, fast breeder reactor (FBR) fuel [average burnup {similar_to}2.6 TJ/kg ({similar_to}30,000 MWd/t)] was processed for the first time. Operations in a single extraction cycle with 30% TBP-NPH were satisfactory with low heavy-metal losses (< 0.02%) and high decontamination factors (DFs > 1000) for all fission products except {sup 95}Zr, which exhibited moderate DFs (180 and 750, respectively, in two runs). The use of a split scrub stream (0.5 M and 3 M HNO{sub 3}) vs a single scrub stream (3 M HNO{sub 3}) resulted in the higher DF. An extractant backscrubbing stream was not needed to produce partially partitioned uranium-plutonium products containing 30 to 35% plutonium when processing the core FBR fuel (22% Pu). The necessary enrichment factor ({similar_to}1.5) was attained by maintaining the temperature at 25 to 30{sup 0}C in partial partitioning and adjusting the relative flow rates of the aqueous and organic phases. The plutonium recovery in the two runs ({similar_to}400 g) was purified by anion exchange and converted to PuO{sub 2} for fuel refabrication studies. 8 references, 7 figures, 6 tables

Observation of anomalous spin-state segregation in a trapped ultra-cold vapor

We observe counter-intuitive spin segregation in an inhomogeneous sample of ultra-cold, non-condensed Rubidium atoms in a magnetic trap. We use spatially selective microwave spectroscopy to verify a model that accounts for the differential forces on two internal spin states. In any simple understanding of the cloud dynamics, the forces are far too small to account for the dramatic transient spin polarizations observed. The underlying mechanism remains to be elucidated.Comment: 5 pages, 3 figure

Transverse Fresnel-Fizeau drag effects in strongly dispersive media

A light beam normally incident upon an uniformly moving dielectric medium is in general subject to bendings due to a transverse Fresnel-Fizeau light drag effect. In conventional dielectrics, the magnitude of this bending effect is very small and hard to detect. Yet, it can be dramatically enhanced in strongly dispersive media where slow group velocities in the m/s range have been recently observed taking advantage of the electromagnetically induced transparency (EIT) effect. In addition to the usual downstream drag that takes place for positive group velocities, we predict a significant anomalous upstream drag to occur for small and negative group velocities. Furthermore, for sufficiently fast speeds of the medium, higher order dispersion terms are found to play an important role and to be responsible for peculiar effects such as light propagation along curved paths and the restoration of the spatial coherence of an incident noisy beam. The physics underlying this new class of slow-light effects is thoroughly discussed

From nonwetting to prewetting: the asymptotic behavior of 4He drops on alkali substrates

We investigate the spreading of 4He droplets on alkali surfaces at zero temperature, within the frame of Finite Range Density Functional theory. The equilibrium configurations of several 4He_N clusters and their asymptotic trend with increasing particle number N, which can be traced to the wetting behavior of the quantum fluid, are examined for nanoscopic droplets. We discuss the size effects, inferring that the asymptotic properties of large droplets correspond to those of the prewetting film