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We report on a modern realization of the classic helical velocity selector for gas phase particle beams. The device operates stably under high vacuum conditions at rotational frequencies limited only by commercial dc motor capabilities. Tuning the rotational frequency allows selective scanning over a broad velocity band. The width of the selected velocity distributions at full-width-half-maximum is as narrow as a few percent of the selected mean velocity and independent of the rotational speed of the selector. The selector generates low vibrational noise amplitudes comparable to mechanically damped state-of-the-art turbo-molecular pumps and is therefore compatible with vibration sensitive experiments like molecule interferometry. © 2010 American Institute of Physics. ͓doi:10.1063/1.3499254͔Manipulation and control of electrically neutral particles, such as atoms and molecules in the gas phase is an active field of research. 1 The general aim is to increase the ability to control the motion of particles as they propagate in gas phase beams by means of deceleration, 2-5 trapping, 6 and cooling. 7,8 Today, cold atoms and small molecules are the best controlled physical systems and therefore are the ideal playground to study physics 9 and chemistry 10,11 at the most fundamental level. 12 For more complex systems-starting with molecules of more than about ten atoms-this level of control has not yet been achieved. Velocity selection is one of the first steps to increase control over the motion of large molecules and clusters. For instance, molecule interferometry is challenging today's gas phase manipulation technologies and will gain from improved beam monochromaticity: by reaching maximal interference visibility, 13 by higher precision in interferometric deflection for molecule metrology, 14 as well as by interferometric particle sorting. 15 Cooling and trapping of molecules will benefit from improved molecule velocity selection. 12 Plainly, our device can be used to select slow particles from a wide thermal velocity distribution 16 as proposed in one of the very early approaches to produce cold atoms. 17 As a further example, velocity selection can be used to separate buffer gas cooled molecules thermalized with their lighter coolant atoms propagating at much higher velocities. Furthermore, atom, molecule and cluster lithography techniques 18-20 will benefit from velocity pre-selected particles.We here have picked up the old idea to mechanically separate particles of different velocities, for instance generated by a thermal beam source with a very broad velocity distribution and base our design on earlier helical velocity selectors for neutrons, 21,22 atoms, 23 and the related slotted disk selectors for molecules. 24,25 The main idea is to make use of the difference in propagation time particles need for their passage through a spatial confinement. Such a confinement can be realized by a sequence slits arranged by rotating slotted disks at well defined positions and with well defined phase relations. It turns out ...

The Eolus batholith of the Needle Mountains, southwestern Colorado, contains two principal map units, the Eolus and Trimble Granites. The Eolus Granite has been dated at 1,460 Ma; the Trimble Granite formed about 1,350 Ma. Thus, the Eolus and Trimble Granites fall within the time range spanned by two well-documented anorogenic periods in North America (see Bickford and others, this volume).Although the rocks of the Eolus batholith share many chemical traits with anorogenic, or A-type, granites, they differ by having a wider, and on the average lower, range of silica contents, by being calcalkaline rather than alkaline, and by having rare-earth element (REE) patterns more characteristic of synorogenic granites. The Eolus batholith also differs from most anorogenic batholiths by having undergone extensive fractionation, involving both partial-melt fractionation and hornblende-dominated fractional crystallization.A consequence of this fractionation was progressive enrichment of uranium as the Eolus batholith evolved. In early products of differentiation, uranium is held entirely within relatively nonlabile accessory minerals such as zircon, sphene, apatite, and allanite. In late-stage differentiates, particularly the Trimble Granite, most uranium is found in scattered grains of more readily teachable high-uranium phases such as uraninite and uranothorite. These late-stage differentiates were source rocks for later mineralization.It is believed that the Eolus batholith formed by melting of an underplated mantle wedge above subducted oceanic plate. Melting may have been initiated by low pressure in an extensional regime, caused by a transition in tectonic style from synorogenic ductile compression to postorogenic brittle extension. Melting was probably localized along preexisting zones of weakness, which would account for synchronous magmatism over a broad transcontinental belt. Differences in distance from a subduction zone, crustal thickness, depth of melting, and other factors may account for the chemical dissimilarities between the postorogenic Eolus batholith and other "anorogenic" batholiths of approximately the same age.

We report on the investigation of strong toroidal rotation effects in a global tokamak code, ORB5. This includes the implementation of a strong flow gyrokinetic Lagrangian, allowing a complete treatment of centrifugal and Coriolis effects in the laboratory frame. In order to consistently perform the linear analysis in this system, an axisymmetric gyrokinetic equilibrium distribution function is defined using the constants of motion: we show it corresponds to the standard choice in the local limit and is close to the neoclassical solution in the banana regime. The energy and momentum transport equations are presented in an analogous form to those for the weak flow system. Linear studies of Ion Temperature Gradient (ITG) modes in rotating plasmas are performed to determine how the global effects interact with the effects of strong rotation. We also determine the geodesic acoustic mode dispersion with respect to plasma rotation rate in this gyrokinetic model and compare it to MHD theory.