| 1. |
- Andersson, Pontus, 1971, et al.
(författare)
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Nearly complete isobar suppression by photodetachment
- 2010
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 1089-7550 .- 0021-8979. ; 107:2
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of selective suppression of negative ions by photodetachment in a gas-filled radio frequency quadrupole ion cooler was investigated with a new detection method. A neodymium doped yttrium aluminum garnet laser beam at 1064 nm was used to remove Co− ions in the radio frequency quadrupole cooler and the remaining ions were then probed by photodetachment and neutral particle detection. More than 99.99% suppression of the Co− ions was observed. Under identical conditions, only 20% of a Ni− beam was suppressed. The results demonstrate that this isobar suppression technique can lead to nearly complete elimination of certain isobaric contaminants in negative ion beams, opening up new experimental possibilities in nuclear and atomic research and accelerator mass spectrometry.
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| 2. |
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| 3. |
- Diehl, C., et al.
(författare)
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Ion optical design of a collinear laser-negative ion beam apparatus
- 2011
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 82:5
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Tidskriftsartikel (refereegranskat)abstract
- An apparatus for photodetachment studies on atomic and molecular negative ions of medium up to heavy mass (M ≃ 500) has been designed and constructed. Laser and ion beams are merged in the apparatus in a collinear geometry and atoms, neutral molecules and negative ions are detected in the forward direction. The ion optical design and the components used to optimize the mass resolution and the transmission through the extended field-free interaction region are described. A 90° sector field magnet with 50 cm bending radius in combination with two slits is used for mass dispersion providing a resolution of M/ΔM≅800 for molecular ions and M/ΔM≅400 for atomic ions. The difference in mass resolution for atomic and molecular ions is attributed to different energy distributions of the sputtered ions. With 1 mm slits, transmission from the source through the interaction region to the final ion detector was determined to be about 0.14%.
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| 4. |
- Lindahl, Anton, 1982, et al.
(författare)
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The electron affinity of tungsten
- 2010
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Ingår i: The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 60:2, s. 219-222
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Tidskriftsartikel (refereegranskat)abstract
- The electron affinity of tungsten has been measured using laser photodetachment threshold spectroscopy in a collinear geometry. The electron affinity was determined to 6583.6(6) cm-1 by observing the onset of the process when W- ions in the 6S5/2 ground state are photodetached producing neutral W atoms in the 5D0 ground state. The measured value is in agreement with previous measurements and improves the accuracy by almost two orders of magnitude. Further, a photodetachment signal below the ground state photodetachment threshold was found, which indicates the existence of a bound excited state in W-.
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| 5. |
- Martschini, Martin, et al.
(författare)
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Light induced suppression of sulfur in a cesium sputter ion source
- 2012
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Ingår i: International Journal of Mass Spectrometry. - : Elsevier BV. - 1387-3806. ; 315, s. 55-59
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Tidskriftsartikel (refereegranskat)abstract
- New techniques for suppression of atomic isobars in negative ion beams are of great interest for accelerator mass spectrometry (AMS). Especially small and medium-sized facilities can significantly extend their measurement capabilities to new interesting isotopes with a technique independent of terminal voltage. In a new approach, the effect of continuous wave laser light directed towards the cathode surface in a cesium sputter ion source of the Middleton type was studied. The laser light induced a significant change in oxygen, sulfur and chlorine negative ion production from a AgCl target. Approximately 100 mW of laser light reduced the sulfur to chlorine ratio by one order of magnitude. The effect was found to depend on laser power and ion source parameters but not on the laser wavelength. The time constant of the effect varied from a few seconds up to several minutes. Experiments were first performed at the ion beam facility GUNILLA at University of Gothenburg with macroscopic amounts of sulfur. The results were then reproduced at the VERA AMS facility with chemically cleaned AgCl targets containing ∼1 ppm sulfur. The physical explanation behind the effect is still unclear. Nevertheless, the technique has been successfully applied during a regular AMS measurement of 36Cl.
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| 6. |
- Mishra, Yogeshwar, et al.
(författare)
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A microfluidic device for the study of the orientational dynamics of microrods
- 2012
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Ingår i: Proc. SPIE 8251, Microfluidics, BioMEMS, and Medical Microsystems X. - : SPIE. ; 8251:825109
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We describe a microfluidic device for studying the orientational dynamics of microrods. The device enables us to experimentally investigate the tumbling of microrods immersed in the shear flow in a microfluidic channel with a depth of 400 μm and a width of 2.5 mm. The orientational dynamics was recorded using a 20X microscopic objective and a CCD camera. The microrods were produced by shearing microdroplets of photocurable epoxy resin. We show different examples of empirically observed tumbling. On the one hand we find that short stretches of the experimentally determined time series are well described by fits to solutions of Jeffery's approximate equation of motion [Jeffery, Proc. R. Soc. London. 102 (1922), 161-179]. On the other hand we find that the empirically observed trajectories drift between different solutions of Jeffery's equation. We discuss possible causes of this orbit drift.
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| 7. |
- Strömberg, Helena, 1985, et al.
(författare)
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Driver Interfaces for Electric Vehicles
- 2011
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Ingår i: Proceedings of the 3rd International Conference on Automotive User Interfaces and Interactive Vehicular Applications, Salzburg, Nov 30 - Dec 2 2011, Tscheligi, M., Kranz, M., Winberg, G., Meschtscherjakov, A., Murer, M., and Wilfinger, D. (eds.). ; , s. 177-184
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Konferensbidrag (refereegranskat)
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| 8. |
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