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41.
Birgit Andresen Jan Sandström 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):423-424
Abstract 1,3-oxathianes and 1,3-dithianes, with and without p-bromophenyl group in position 2, have been oxidized to sulphoxides. Both starting materials and oxidation products have been resolved by chromatography, and CD spectra have been recorded. Absolute configuration for the p-bromophenyl compounds have been assigned on the basis of known absolute configurations for analogous 1,3-oxathiolanes. 相似文献
42.
Andresen GB Ashkezari MD Baquero-Ruiz M Bertsche W Bowe PD Butler E Cesar CL Chapman S Charlton M Deller A Eriksson S Fajans J Friesen T Fujiwara MC Gill DR Gutierrez A Hangst JS Hardy WN Hayden ME Humphries AJ Hydomako R Jonsell S Madsen N Menary S Nolan P Olin A Povilus A Pusa P Robicheaux F Sarid E Silveira DM So C Storey JW Thompson RI van der Werf DP Wurtele JS Yamazaki Y;ALPHA Collaboration 《Physical review letters》2011,106(14):145001
Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments. 相似文献
43.
Spectral compression by self-phase modulation of amplitude- and phase-shaped pulses is demonstrated as superior compared to pulses that have only been phase shaped. We synthesize linearly negatively chirped parabolic pulses, which we send through a nonlinear photonic crystal fiber, in which self-phase modulation compresses the spectrum of the pulses to within 20% of the Fourier transform limit. 相似文献
44.
It is demonstrated that precise spontaneous Raman scattering measurements with deep-UV lasers are in principle possible in hydrocarbon flames - even with liquid fuels - by the use of polarization properties. In contrast to the highly polarized Raman emission, the strong interfering broadband emission from combustion intermediates is unpolarized. Subtracting the emission intensities for the electric vector of the laser light perpendicular and parallel to the direction of observation allows to extract the pure Raman signals. Different applications of this technique are discussed. 相似文献
45.
M. C. Fujiwara G. Andresen W. Bertsche A. Boston P. D. Bowe C. L. Cesar S. Chapman M. Charlton M. Chartier A. Deutsch J. Fajans R. Funakoshi D. R. Gill K. Gomberoff J. S. Hangst W. N. Hardy R. S. Hayano R. Hydomako M. J. Jenkins L. V. Jørgensen L. Kurchaninov N. Madsen P. Nolan K. Olchanski A. Olin R. D. Page A. Povilus F. Robicheaux E. Sarid D. M. Silveira J. W. Storey R. I. Thompson D. P. van der Werf J. S. Wurtele Y. Yamazaki 《Hyperfine Interactions》2006,172(1-3):81-89
ALPHA is an international project that has recently begun experimentation at CERN’s Antiproton Decelerator (AD) facility.
The primary goal of ALPHA is stable trapping of cold antihydrogen atoms with the ultimate goal of precise spectroscopic comparisons
with hydrogen. We discuss the status of the ALPHA project and the prospects for antihydrogen trapping. 相似文献
46.
P. Drescher H. G. Andresen K. Aulenbacher J. Bermuth Th. Dombol H. Fischerz H. Euteneuer N. N. Faleev M. S. Galaktionov D. v. Harrach P. Hartmann J. Hoffmann P. Jennewein K. H. Kaiser S. Köbis O. V. Kovalenkov H. J. Kreide J. Langbeine Y. A. Mamaev Ch. Nachtigall M. Petri S. Plützer E. Reicherte M. Schemies H. -J. Schöpe K. -H. Steffens M. Steigerwald A. V. Subashiev H. Trautner D. A. Vinokurov Y. P. Yashin B. S. Yavich 《Applied Physics A: Materials Science & Processing》1996,63(2):203-206
Strained layer GaAs.95P.05 photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P2 × QE = 2.3 × 10–3 is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around 830 nm is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. A GaAs.55P.45-GaAs.85P.15 superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by an arsenic layer so that no chemical cleaning is necessary before installation into vacuum. The source of polarized electrons attached to the Mainz race track microtron MAMI works with such cathodes now. More than 1000 hours beamtime have been performed successfully. 相似文献
47.
B. Andresen S. Hultberg B. Jelenković L. Liljeby S. Mannervik E. Veje 《Zeitschrift für Physik A Hadrons and Nuclei》1979,293(3):181-185
We have studied the optical beam-foil spectra of Li, Be, and Mg in the wavelength region 200–550 nm by use of a quantum efficiency calibrated monochromator at projectile energies of 210 keV for Li, 156, 256, and 356 keV for Be, and 100 keV for Mg. The relative population for different Rydberg levels of the same term series decreases in most cases somewhat faster than (n *)?3, as is also observed in ion-atom encounters under single collision conditions. The relative level population for levels of the same principal quantum number increases generally with the orbital angular momentum quantum number, and superimposed on this increase is a peaking forp levels. The relative population of levels of the same charge state and with the same core configuration is unaffected by change of the projectile energy. 相似文献
48.
Andresen G Bertsche W Boston A Bowe PD Cesar CL Chapman S Charlton M Chartier M Deutsch A Fajans J Fujiwara MC Funakoshi R Gill DR Gomberoff K Hangst JS Hayano RS Hydomako R Jenkins MJ Jørgensen LV Kurchaninov L Madsen N Nolan P Olchanski K Olin A Povilus A Robicheaux F Sarid E Silveira DM Storey JW Telle HH Thompson RI van der Werf DP Wurtele JS Yamazaki Y;ALPHA Collaboration 《Physical review letters》2007,98(2):023402
We have demonstrated storage of plasmas of the charged constituents of the antihydrogen atom, antiprotons and positrons, in a Penning trap surrounded by a minimum-B magnetic trap designed for holding neutral antiatoms. The neutral trap comprises a superconducting octupole and two superconducting, solenoidal mirror coils. We have measured the storage lifetimes of antiproton and positron plasmas in the combined Penning-neutral trap, and compared these to lifetimes without the neutral trap fields. The magnetic well depth was 0.6 T, deep enough to trap ground state antihydrogen atoms of up to about 0.4 K in temperature. We have demonstrated that both particle species can be stored for times long enough to permit antihydrogen production and trapping studies. 相似文献
49.
E. Butler G. B. Andresen M. D. Ashkezari M. Baquero-Ruiz W. Bertsche P. D. Bowe C. L. Cesar S. Chapman M. Charlton A. Deller S. Eriksson J. Fajans T. Friesen M. C. Fujiwara D. R. Gill A. Gutierrez J. S. Hangst W. N. Hardy M. E. Hayden A. J. Humphries R. Hydomako M. J. Jenkins S. Jonsell L. V. J?rgensen S. L. Kemp L. Kurchaninov N. Madsen S. Menary P. Nolan K. Olchanski A. Olin A. Povilus P. Pusa C. ?. Rasmussen F. Robicheaux E. Sarid S. Seif el Nasr D. M. Silveira C. So J. W. Storey R. I. Thompson D. P. van der Werf J. S. Wurtele Y. Yamazaki 《Hyperfine Interactions》2012,212(1-3):15-29
50.
T. Friesen G. B. Andresen M. D. Ashkezari M. Baquero-Ruiz W. Bertsche P. D. Bowe E. Butler C. L. Cesar S. Chapman M. Charlton S. Eriksson J. Fajans M. C. Fujiwara D. R. Gill A. Gutierrez J. S. Hangst W. N. Hardy R. S. Hayano M. E. Hayden A. J. Humphries R. Hydomako S. Jonsell L. Kurchaninov N. Madsen S. Menary P. Nolan K. Olchanski A. Olin A. Povilus P. Pusa F. Robicheaux E. Sarid D. M. Silveira C. So J. W. Storey R. I. Thompson D. P. van der Werf J. S. Wurtele Y. Yamazaki 《Hyperfine Interactions》2012,212(1-3):117-123
The goal of the ALPHA experiment is the production, trapping and spectroscopy of antihydrogen. A direct comparison of the ground state hyperfine spectra in hydrogen and antihydrogen has the potential to be a high-precision test of CPT symmetry. We present a novel method for measuring the strength of a microwave field for hyperfine spectroscopy in a Penning trap. This method incorporates a non-destructive plasma diagnostic system based on electrostatic modes within an electron plasma. We also show how this technique can be used to measure the cyclotron resonance of the electron plasma, which can potentially serve as a non-destructive measurement of plasma temperature. 相似文献