| 1. |
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| 2. |
- Eversmann, D., et al.
(författare)
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New Method for a Continuous Determination of the Spin Tune in Storage Rings and Implications for Precision Experiments
- 2015
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 115:9
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Tidskriftsartikel (refereegranskat)abstract
- A new method to determine the spin tune is described and tested. In an ideal planar magnetic ring, the spin tune-defined as the number of spin precessions per turn-is given by nu(s) = gamma G (gamma is the Lorentz factor, G the gyromagnetic anomaly). At 970 MeV/c, the deuteron spins coherently process at a frequency of approximate to 120 kHz in the Cooler Synchrotron COSY. The spin tune is deduced from the up-down asymmetry of deuteron-carbon scattering. In a time interval of 2.6 s, the spin tune was determined with a precision of the order 10(-8), and to 1 x 10(-10) for a continuous 100 s accelerator cycle. This renders the presented method a new precision tool for accelerator physics; controlling the spin motion of particles to high precision is mandatory, in particular, for the measurement of electric dipole moments of charged particles in a storage ring.
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| 3. |
- Hempelmann, N., et al.
(författare)
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Locking the Spin Precession in a Storage Ring
- 2017
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 119:1
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Tidskriftsartikel (refereegranskat)abstract
- This Letter reports the successful use of feedback from a spin polarization measurement to the revolution frequency of a 0.97 GeV= c bunched and polarized deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control both the precession rate (approximate to 121 kHz) and the phase of the horizontal polarization component. Real time synchronization with a radio frequency (rf) solenoid made possible the rotation of the polarization out of the horizontal plane, yielding a demonstration of the feedback method to manipulate the polarization. In particular, the rotation rate shows a sinusoidal function of the horizontal polarization phase (relative to the rf solenoid), which was controlled to within a 1 standard deviation range of sigma= 0.21 rad. The minimum possible adjustment was 3.7 mHz out of a revolution frequency of 753 kHz, which changes the precession rate by 26 mrad/s. Such a capability meets a requirement for the use of storage rings to look for an intrinsic electric dipole moment of charged particles.
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| 4. |
- Hepojoki, J, et al.
(författare)
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Acute hantavirus infection induces galectin-3-binding protein
- 2014
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Ingår i: The Journal of general virology. - : Microbiology Society. - 1465-2099 .- 0022-1317. ; 95:Pt 11, s. 2356-2364
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Tidskriftsartikel (refereegranskat)abstract
- Hantaviruses are zoonotic viruses that cause life-threatening diseases when transmitted to humans. Severe hantavirus infection is manifested by impairment of renal function, pulmonary oedema and capillary leakage. Both innate and adaptive immune responses contribute to the pathogenesis, but the underlying mechanisms are not fully understood. Here, we showed that galectin-3-binding protein (Gal-3BP) was upregulated as a result of hantavirus infection bothin vitroandin vivo. Gal-3BP is a secreted glycoprotein found in human serum, and increased Gal-3BP levels have been reported in chronic viral infections and in several types of cancer. Ourin vitroexperiments showed that, whilst Vero E6 cells (an African green monkey kidney cell line) constitutively expressed and secreted Gal-3BP, this protein was detected in primary human cells only as a result of hantavirus infection. Analysis of Gal-3BP levels in serum samples of cynomolgus macaques infected experimentally with hantavirus indicated that hantavirus infection induced Gal-3BP alsoin vivo. Finally, analysis of plasma samples collected from patients hospitalized because of acute hantavirus infection showed higher Gal-3BP levels during the acute than the convalescent phase. Furthermore, the Gal-3BP levels in patients with haemorrhagic fever with renal syndrome correlated with increased complement activation and with clinical variables reflecting the severity of acute hantavirus infection.
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| 5. |
- Hempelmann, N., et al.
(författare)
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Phase measurement for driven spin oscillations in a storage ring
- 2018
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Ingår i: Physical Review Accelerators and Beams. - : American Physical Society. - 2469-9888. ; 21:4
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the first simultaneous measurement of the horizontal and vertical components of the polarization vector in a storage ring under the influence of a radio frequency (rf) solenoid. The experiments were performed at the Cooler Synchrotron COSY in Julich using a vector polarized, bunched 0.97 GeV/c deuteron beam. Using the new spin feedback system, we set the initial phase difference between the solenoid field and the precession of the polarization vector to a predefined value. The feedback system was then switched off, allowing the phase difference to change over time, and the solenoid was switched on to rotate the polarization vector. We observed an oscillation of the vertical polarization component and the phase difference. The oscillations can be described using an analytical model. The results of this experiment also apply to other rf devices with horizontal magnetic fields, such as Wien filters. The precise manipulation of particle spins in storage rings is a prerequisite for measuring the electric dipole moment (EDM) of charged particles.
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| 6. |
- Saleev, A., et al.
(författare)
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Spin tune mapping as a novel tool to probe the spin dynamics in storage rings
- 2017
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Ingår i: Physical Review Accelerators and Beams. - : American Physical Society. - 2469-9888. ; 20:7
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Tidskriftsartikel (refereegranskat)abstract
- Precision experiments, such as the search for electric dipole moments of charged particles using storage rings, demand for an understanding of the spin dynamics with unprecedented accuracy. The ultimate aim is to measure the electric dipole moments with a sensitivity up to 15 orders in magnitude better than the magnetic dipole moment of the stored particles. This formidable task requires an understanding of the background to the signal of the electric dipole from rotations of the spins in the spurious magnetic fields of a storage ring. One of the observables, especially sensitive to the imperfection magnetic fields in the ring is the angular orientation of stable spin axis. Up to now, the stable spin axis has never been determined experimentally, and in addition, the JEDI collaboration for the first time succeeded to quantify the background signals that stem from false rotations of the magnetic dipole moments in the horizontal and longitudinal imperfection magnetic fields of the storage ring. To this end, we developed a new method based on the spin tune response of a machine to artificially applied longitudinal magnetic fields. This novel technique, called spin tune mapping, emerges as a very powerful tool to probe the spin dynamics in storage rings. The technique was experimentally tested in 2014 using polarized deuterons stored in the cooler synchrotron COSY, and for the first time, the angular orientation of the stable spin axis at two different locations in the ring has been determined to an unprecedented accuracy of better than 2.8 mu rad.
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| 7. |
- Brown, D., et al.
(författare)
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Arc-continent collision in the Southern Urals
- 2006
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Ingår i: Earth-Science Reviews. - : Elsevier BV. - 0012-8252 .- 1872-6828. ; 79:3-4, s. 261-287
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Tidskriftsartikel (refereegranskat)abstract
- The Southern Urals of Russia contain what is arguably one of the best-preserved examples of an arc–continent collision in anyPaleozoic orogen. The arc–continent collision history recorded in the rocks of the Southern Urals began in the Early Devonian withthe onset of intra-oceanic subduction and the formation of the Magnitogorsk Arc and ended with its collision with the margin ofBaltica during the Late Devonian. The Baltica margin consisted of a basement that was composed predominantly of rocks ofArchean and Proterozoic age that, by the time of arc–continent collision, was overlain by Cambrian, Ordovician, Silurian, andDevonian sediments interpreted to have been deposited in rift-related grabens on the continental slope and rise, and on the shallowmarine platform. The Magnitogorsk Arc consists of Early to Late Devonian island arc volcanic rocks and overlying volcaniclasticsediments. Arc–continent collision led to the development of an accretionary complex that includes shallowly and deeplysubducted continental margin rocks, ophiolite fragments, and sediments that were deposited in a foreland-basin setting. Thegeochemistry of the Magnitogorsk Arc volcanic rocks, the structure of the arc–continent collision accretionary complex and theforearc, the high-pressure rocks beneath and along the suture zone, the mafic and ultramafic ophiolitic material, and the syn-tectonic sediments show that the Paleozoic tectonic processes recorded in the Southern Urals can be favorably compared with thosein currently active settings such as the west Pacific.© 2006 Elsevier B.V. All rights reserved.
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| 8. |
- Hetzel, M., et al.
(författare)
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Nanowire Reconstruction on the 4H-SiC(1-102) Surface
- 2007
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Ingår i: Silicon Carbide and Related Materials 2006. - : Trans Tech Publications Inc.. ; , s. 529-532
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Konferensbidrag (refereegranskat)abstract
- Ordered reconstruction phases on the 4H-SiC(1102) surface have been investigated usinglow-energy electron diffraction (LEED), Auger electron spectroscopy (AES) and scanning tunnelingmicroscopy (STM). After initial hydrogen etching, the samples were prepared by Si deposition andannealing in ultra-high vacuum (UHV). Two distinct reconstruction phases develop upon annealing,first with a (2×1), and at higher temperatures with a c(2×2) LEED pattern. After further annealingthe fractional order LEED spots vanish and a (1x1) pattern develops. For the (2×1) phase, STMmicrographs show that adatom chains develop on large flat terraces, which in view of AES consistof additional Si. These highly linear and equidistant chains represent a self-assembled well-orderedpattern of nanowires developing due to the intrinsic structure of the 4H-SiC(1102) surface. For thec(2×2) phase AES indicates a surface composition close to the bulk stoichiometry. For the (1×1)phase a further Si depletion is observed.
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| 9. |
- Virojanadara, Chariya, et al.
(författare)
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Atomic and Electronic Structure of the (2x1) and c(2x2) 4H-SiC(1(1)over-bar02) Surfaces
- 2008
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2007, PTS 1 AND 2. - : Trans Tech Publications Inc.. ; , s. 291-296
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Konferensbidrag (refereegranskat)abstract
- The atomic and electronic structure of 4H-SiC(1 1 02) surfaces were investigated usingscanning tunneling microscopy (STM), low-energy electron diffraction (LEED) and photoemission(PES). Two well ordered phases existing on this surface, i.e. (2×1) and c(2×2) are discussed. The(2×1) phase consists of a Si adlayer which is topped by an array of ordered Si-nanowires withelectronic states confined to one dimension. For the c(2×2) phase STM indicates the presence ofadatoms and PES a surface composition close to bulk SiC stoichiometry. A detailed atomic modelfor this c(2×2) phase is proposed.
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| 10. |
- Virojanadara, Chariya, et al.
(författare)
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Electronic and atomic structure of the 4 H-SiC (1 over(1, ¯) 0 2) -c (2 × 2) surface
- 2008
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 602:2, s. 525-533
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Tidskriftsartikel (refereegranskat)abstract
- The (1 over(1, ¯) 0 2) orientated plane of hexagonal silicon carbide of the 4H polytype consists of a periodic arrangement of stripes with alternating bond configuration on a nanometer scale. The two stripe configurations of the bulk truncated surface have an atomic structure very close to the carbon-face SiC basal plane and the cubic SiC(1 0 0) surface, respectively. The structural and electronic properties of the c(2 × 2) reconstruction on the 4 H-SiC (1 over(1, ¯) 0 2) surface were investigated using photoemission spectroscopy (PES), scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). The core level photoemission spectra reveal two surface shifted Si2p components and one shifted C1s component in addition to the SiC bulk peaks. In accordance with the periodicity observed in LEED, atomically resolved STM micrographs show a c(2 × 2) arrangement of bright features which are accounted as Si adatoms. The electronic structure of this SiC (1 over(1, ¯) 0 2) -c (2 × 2) phase is experimentally determined by angle resolved PES studies of the valence band revealing four surface states. Based on the experimental observations and a comparison to similar phases on other SiC surfaces, a tentative surface model can be developed which consists of Si adatoms in so-called H3 sites on the basal-plane type stripes and carbon dimers in Si bridging configuration on the cubic stripes of the bulk truncated surface. © 2007 Elsevier B.V. All rights reserved.
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