| 1. |
- Correa, J., et al.
(författare)
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The PERCIVAL detector : first user experiments
- 2023
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Ingår i: Journal of Synchrotron Radiation. - 0909-0495 .- 1600-5775. ; 30, s. 242-250
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Tidskriftsartikel (refereegranskat)abstract
- The PERCIVAL detector is a CMOS imager designed for the soft X-ray regime at photon sources. Although still in its final development phase, it has recently seen its first user experiments: ptychography at a free-electron laser, holographic imaging at a storage ring and preliminary tests on X-ray photon correlation spectroscopy. The detector performed remarkably well in terms of spatial resolution achievable in the sample plane, owing to its small pixel size, large active area and very large dynamic range; but also in terms of its frame rate, which is significantly faster than traditional CCDs. In particular, it is the combination of these features which makes PERCIVAL an attractive option for soft X-ray science.
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| 2. |
- Schmising, C. von Korff, et al.
(författare)
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Imaging Ultrafast Demagnetization Dynamics after a Spatially Localized Optical Excitation
- 2014
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Ingår i: Physical Review Letters. - 1079-7114. ; 111:21
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Tidskriftsartikel (refereegranskat)abstract
- Ultrashort, coherent x-ray pulses of a free-electron laser are used to holographically image the magnetization dynamics within a magnetic domain pattern after creation of a localized excitation via an optical standing wave. We observe a spatially confined reduction of the magnetization within a couple of hundred femtoseconds followed by its slower recovery. Additionally, the experimental results show evidence of a spatial evolution of magnetization, which we attribute to ultrafast transport of nonequilibrium spin-polarized electrons for early times and to a fluence-dependent remagnetization rate for later times.
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| 3. |
- von Korff Schmising, C., et al.
(författare)
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Imaging Non-Local Magnetization Dynamics
- 2016
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Ingår i: Synchrotron Radiation News. - : Informa UK Limited. - 0894-0886 .- 1931-7344. ; 29:3, s. 26-31
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Tidskriftsartikel (refereegranskat)abstract
- Many fundamental processes in magnetism take place on a nanometer length and sub-picosecond time scale. An important example of such phenomena in magnetism is ultrafast, spin-polarized transport of laser-excited hot electrons, which is now being recognized as playing a crucial role for novel spintronic devices and for optically induced magnetic switching. Recent experimental examples include the demonstration of all-optical helicity dependent control of spin-polarized currents at interfaces [1], the design of novel and efficient terahertz emitters [2], and nanoscale spin reversal in chemically heterogeneous GdFeCo driven by non-local transfer of angular momentum [3]. In particular, for advanced information technologies with bit densities already exceeding 1 terabit per square inch with bit cell dimensions of (15 × 38 nm2) [4], it is of fundamental importance to understand and eventually control the mechanisms responsible for optically induced spin dynamics on the nanoscale.
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| 4. |
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| 5. |
- Johlander, Andreas, 1990-, et al.
(författare)
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Ion Acceleration Efficiency at the Earth's Bow Shock : Observations and Simulation Results
- 2021
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 914:2
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Tidskriftsartikel (refereegranskat)abstract
- Collisionless shocks are some of the most efficient particle accelerators in heliospheric and astrophysical plasmas. Here we study and quantify ion acceleration at Earth's bow shock with observations from NASA's Magnetospheric Multiscale (MMS) satellites and in a global hybrid-Vlasov simulation. From the MMS observations, we find that quasiparallel shocks are more efficient at accelerating ions. There, up to 15% of the available energy goes into accelerating ions above 10 times their initial energy. Above a shock-normal angle of similar to 50 degrees, essentially no energetic ions are observed downstream of the shock. We find that ion acceleration efficiency is significantly lower when the shock has a low Mach number (M ( A ) < 6) while there is little Mach number dependence for higher values. We also find that ion acceleration is lower on the flanks of the bow shock than at the subsolar point regardless of the Mach number. The observations show that a higher connection time of an upstream field line leads to somewhat higher acceleration efficiency. To complement the observations, we perform a global hybrid-Vlasov simulation with realistic solar-wind parameters with the shape and size of the bow shock. We find that the ion acceleration efficiency in the simulation shows good quantitative agreement with the MMS observations. With the combined approach of direct spacecraft observations, we quantify ion acceleration in a wide range of shock angles and Mach numbers.
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| 6. |
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| 7. |
- Stiel, H., et al.
(författare)
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2D and 3D Nanoscale Imaging Using High Repetition Rate Laboratory-Based Soft X-Ray Sources
- 2018
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Ingår i: X-Ray Lasers 2016 - Proceedings of the 15th International Conference on X-Ray Lasers. - Cham : Springer International Publishing. - 9783319730240 ; 202, s. 265-272
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Konferensbidrag (refereegranskat)abstract
- In this contribution, we report about tomographic nanoscale imaging using a laser-produced plasma-based laboratory transmission X-ray microscope (LTXM) in the water window. The soft X-ray radiation of the LTXM is provided by a high average power laser-produced (1.3 kHz repetition rate, 0.5 ns pulse duration, 140 W average power) plasma source, a multilayer condenser mirror, an objective zone plate, and a back-illuminated CCD camera as a detector. In the second part of the contribution, we will present recent results on holography and coherent diffraction imaging using our high repetition rate X-ray laser. We will discuss advantages of these methods and its potential for nanoscale imaging.
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| 8. |
- Svensson, Peter, et al.
(författare)
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Neurosensory testing of orofacial pain in the dental clinic
- 2012
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Ingår i: The Journal of the American Dental Association (1939). - : American Dental Association. - 0002-8177 .- 1943-4723. ; 143:8, s. e37-e39
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Tidskriftsartikel (refereegranskat)abstract
- CONCLUSIONS Traumatic nerve injuries are associated with distinct changes in somatosensory function. Clinicians need to know that such aberrant sensations are normal when treating patients who have neuropathic pain. Simple neurosensory testing can reveal the extent of such somatosensory changes, and the results of more sophisticated QST methods might be a way to study the mechanisms of orofacial pain
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