237 research outputs found
Updated Report Acceleration of Polarized Protons to 120-150 GeV/c at Fermilab
The SPIN@FERMI collaboration has updated its 1991-95 Reports on the
acceleration of polarized protons in Fermilab's Main Injector, which was
commissioned by Fermilab. This Updated Report summarizes some updated Physics
Goals for a 120-150 GeV/c polarized proton beam. It also contains an updated
discussion of the Modifications and Hardware needed for a polarized beam in the
Main Injector, along with an updated Schedule and Budget.Comment: 30 pages, 12 figure
Dynamics of Emitting Electrons in Strong Electromagnetic Fields
We derive a modified non-perturbative Lorentz-Abraham-Dirac equation. It
satisfies the proper conservation laws, particularly, it conserves the
generalized momentum, the latter property eliminates the symmetry-breaking
runaway solution. The equation allows a consistent calculation of the electron
current, the radiation effect on the electron momentum, and the radiation
itself, for a single electron or plasma electrons in strong electromagnetic
fields. The equation is applied to a simulation of a strong laser pulse
interaction with a plasma target. Some analytical solutions are also provided.Comment: The original form of this paper was submitted to Phys. Rev. Lett. on
August 3, 2008. The current version of the paper is substantially extended
and includes modifications resulting from points raised during the review
proces
Splitting of the Dipole and Spin-Dipole Resonances
Cross sections for the 90,92,94Zr(p,n) reactions were measured at energies of
79.2 and 119.4 MeV. A phenomenological model was developed to describe the
variation with bombarding energy of the position of the L=1 peak observed in
these and other (p,n) reactions. The model yields the splitting between the
giant dipole and giant spin dipole resonances. Values of these splittings are
obtained for isotopes of Zr and Sn and for 208Pb.Comment: 14 pages, 4 figure
Ultrafast-ultrafine probing of high-speed electrical waveforms using a scanning force microscope with photoconductive gating
Picosecond photoconductivity in low-temperature-grown GaAs (LT GaAs) has been used to provide temporal resolution both in rigid probes and in scanning force microscope probes. This article reviews the fabrication and use of such probes. 2.5 ps temporal resolution and few microvolts sensitivity are obtained at arbitrary points on circuits with a spatial definition of 100 nm. Rigid probes are tested in application to analogue and digital circuits. As an alternative to electron beam testing, scanning force probes are applied to in situ imaging and waveform measurement. Finally, the use of time-resolved waveform analysis with scanning-force microscopy probes with semiconductor laser sources is demonstrated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43337/1/11082_2004_Article_BF00820152.pd
Thirty Years After Michael E. Porter: What Do We Know About Business Exit?
Although a business exit is an important corporate change initiative, the buyer’s side seems to be more appealing to management researchers than the seller’s because acquisitions imply growth, i.e., success. Yet from an optimistic viewpoint, business exit can effectively create value for the selling company. In this paper we attempt to bring the relevance of the seller’s side back into our consciousness by asking: What do we know about business exit? We start our exploration with Porter (1976), focusing on literature that investigates the antecedents of, barriers to, and outcomes of business exit. We also include studies from related fields such as finance and economics.1 Through this research we determine three clusters of findings: factors promoting business exit, exit barriers, and exit outcomes. Overall, it is the intention of this paper to highlight the importance of business exit for research and practice. Knowing what we know about business exits and their high financial value we should bear in mind that exit need not mean failure but a new beginning for a corporation
Higher Order Spin Resonances in a 2.1 GeV/c Polarized Proton Beam
Spin resonances can depolarize or spin-flip a polarized beam. We studied 1st
and higher order spin resonances with stored 2.1 GeV/c vertically polarized
protons. The 1st order vertical ({\nu}y) resonance caused almost full
spin-flip, while some higher order {\nu}y resonances caused partial
depolarization. The 1st order horizontal ({\nu}x) resonance caused almost full
depolarization, while some higher order {\nu}x resonances again caused partial
depolarization. Moreover, a 2nd order {\nu}x resonance is about as strong as
some 3rd order {\nu}x resonances, while some 3rd order {\nu}y resonances are
much stronger than a 2nd order {\nu}y resonance. One thought that {\nu}y spin
resonances are far stronger than {\nu}x, and that lower order resonances are
stronger than higher order; the data do not support this.Comment: 5 pages, 5 figures Note that Fig. 5 did not appear in the PRL due to
space limitation, but did appear in the March 2012 CERN Courier News Item
"Results from SPIN@COSY may bode well for RHIC
Detecting the influence of initial pioneers on succession at deep-sea vents
© The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 7 (2012): e50015, doi:10.1371/journal.pone.0050015.Deep-sea hydrothermal vents are subject to major disturbances that alter the physical and chemical environment and eradicate the resident faunal communities. Vent fields are isolated by uninhabitable deep seafloor, so recolonization via dispersal of planktonic larvae is critical for persistence of populations. We monitored colonization near 9°50′N on the East Pacific Rise following a catastrophic eruption in order to address questions of the relative contributions of pioneer colonists and environmental change to variation in species composition, and the role of pioneers at the disturbed site in altering community structure elsewhere in the region. Pioneer colonists included two gastropod species: Ctenopelta porifera, which was new to the vent field, and Lepetodrilus tevnianus, which had been rare before the eruption but persisted in high abundance afterward, delaying and possibly out-competing the ubiquitous pre-eruption congener L. elevatus. A decrease in abundance of C. porifera over time, and the arrival of later species, corresponded to a decrease in vent fluid flow and in the sulfide to temperature ratio. For some species these successional changes were likely due to habitat requirements, but other species persisted (L. tevnianus) or arrived (L. elevatus) in patterns unrelated to their habitat preferences. After two years, disturbed communities had started to resemble pre-eruption ones, but were lower in diversity. When compared to a prior (1991) eruption, the succession of foundation species (tubeworms and mussels) appeared to be delayed, even though habitat chemistry became similar to the pre-eruption state more quickly. Surprisingly, a nearby community that had not been disturbed by the eruption was invaded by the pioneers, possibly after they became established in the disturbed vents. These results indicate that the post-eruption arrival of species from remote locales had a strong and persistent effect on communities at both disturbed and undisturbed vents.The authors received funding from National Science Foundation grant OCE-0424953, WHOI Deep Ocean Exploration Institute, WHOI Summer Student Fellow program, Woods Hole Partnership in Education Program, IFREMER and CNRS, Fondation TOTAL Chair Extreme Marine Environment, Biodiversity and Global change
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