TY  - JOUR
A1  - Navirian, Hengameh A.
A1  - Herzog, Marc
A1  - Goldshteyn, J.
A1  - Leitenberger, Wolfram
A1  - Vrejoiu, Ionella
A1  - Khakhulin, D.
A1  - Wulff, M.
A1  - Shayduk, Roman
A1  - Gaal, P.
A1  - Bargheer, Matias
T1  - Shortening x-ray pulses for pump-probe experiments at synchrotrons
JF  - Journal of applied physics
N2  - We implemented an experimental scheme for ultrafast x-ray diffraction at storage rings based on a laser-driven Bragg-switch that shortens the x-ray pulses emitted from an undulator. The increased time-resolution is demonstrated by observing changes of intensity, position and width of the diffraction peaks of a La(0.7)Sr(0.3)MnO(3)/SrTiO(3) superlattice sample after optical excitation, i.e., by quantitatively measuring the propagation of an expansion wave through the sample. These experimental transients with timescales of 35 to 60 ps evidence a reduction of the x-ray pulse duration by a factor of two.
Y1  - 2011
U6  - https://doi.org/10.1063/1.3601057
SN  - 0021-8979
VL  - 109
IS  - 12
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Pontius, N.
A1  - Kachel, T.
A1  - Schüssler-Langeheine, C.
A1  - Schlotter, W. F.
A1  - Beye, Martin
A1  - Sorgenfrei, Nomi
A1  - Chang, C. F.
A1  - Föhlisch, Alexander
A1  - Wurth, W.
A1  - Metcalf, P.
A1  - Leonov, I.
A1  - Yaresko, A.
A1  - Stojanovic, N.
A1  - Berglund, Martin
A1  - Guerassimova, N.
A1  - Duesterer, S.
A1  - Redlin, H.
A1  - Duerr, H. A.
T1  - Time-resolved resonant soft x-ray diffraction with free-electron lasers  femtosecond dynamics across the Verwey transition in magnetite
JF  - Applied physics letters
N2  - Resonant soft x-ray diffraction (RSXD) with femtosecond (fs) time resolution is a powerful tool for disentangling the interplay between different degrees of freedom in strongly correlated electron materials. It allows addressing the coupling of particular degrees of freedom upon an external selective perturbation, e. g., by an optical or infrared laser pulse. Here, we report a time-resolved RSXD experiment from the prototypical correlated electron material magnetite using soft x-ray pulses from the free-electron laser FLASH in Hamburg. We observe ultrafast melting of the charge-orbital order leading to the formation of a transient phase, which has not been observed in equilibrium.
Y1  - 2011
U6  - https://doi.org/10.1063/1.3584855
SN  - 0003-6951
VL  - 98
IS  - 18
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Bagnich, Sergey A.
A1  - Unger, Th.
A1  - Jaiser, Frank
A1  - Neher, Dieter
A1  - Thesen, M. W.
A1  - Krüger, H.
T1  - Efficient green electrophosphorescence based on ambipolar nonconjugated polymers evaluation of transport and emission properties
JF  - Journal of applied physics
N2  - New materials for polymer organic light-emitting diodes based on a polymer matrix doped with phosphorescent dyes are presented. The matrix system is based on a polystyrene backbone bearing either electron or hole transporting units at the 4-position of each repeat unit. Random copolymers and polymer blend systems of the homopolymers are prepared, both with 62 wt.% electron transporting and 38 wt.% hole transporting moieties. Adding a green electrophosphorescent dye to the polymer matrix leads to efficient electroluminescence with a maximum current efficiency of 35 cd/A and a maximum external quantum efficiency of up to 10%. The mobilities of electrons and holes in the dye-doped copolymer, as measured by transient electroluminescence, are around 5 x 10(-5) and 5 x 10(-6) cm(2)/Vs, respectively, while the blend of the two homopolymers exhibits slightly lower mobilities of both types of carriers. Despite the pronounced imbalance of charge transport, the device performance is almost entirely limited by the phosphorescence efficiency of the dye, implying balanced flow of holes and electrons into the active region. Also, devices made with either the copolymer or the blend yielded very similar device efficiencies, despite the noticeable difference in electron and hole mobility. It is proposed that electrons are efficiently blocked at the interlayer and that the so-formed space charge assists the balanced injection of holes.
Y1  - 2011
U6  - https://doi.org/10.1063/1.3618681
SN  - 0021-8979
SN  - 1089-7550
VL  - 110
IS  - 3
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Shayduk, Roman
A1  - Navirian, Hengameh
A1  - Leitenberger, Wolfram
A1  - Goldshteyn, Jevgenij
A1  - Vrejoiu, Ionela
A1  - Weinelt, Martin
A1  - Gaal, Peter
A1  - Herzog, Marc
A1  - von Korff Schmising, Clemens
A1  - Bargheer, Matias
T1  - Nanoscale heat transport studied by high-resolution time-resolved x-ray diffraction
JF  - New journal of physics : the open-access journal for physics
N2  - We report on synchrotron-based high-repetition rate ultrafast x-ray diffraction (UXRD) experiments monitoring the transport of heat from an epitaxial La(0.7)Sr(0.3)MnO(3)/SrTiO(3) superlattice (SL) into the substrate on timescales from 100 ps to 4 mu s. Transient thermal lattice expansion was determined with an accuracy of 10(-7), corresponding to a sensitivity to temperature changes down to 0.01 K. We follow the heat flow within the SL and into the substrate after the impulsive laser heating leads to a small temperature rise of Delta T = 6 K. The transient lattice temperature can be simulated very well using the bulk heat conductivities. This contradicts the interpretation of previous UXRD measurements, which predicted a long-lasting expansion of SrRuO(3) for more than 200 ps. The disagreement could be resolved by assuming that the heat conductivity changes in the first hundred picoseconds.
Y1  - 2011
U6  - https://doi.org/10.1088/1367-2630/13/9/093032
SN  - 1367-2630
VL  - 13
IS  - 11
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Belova, Valentina
A1  - Shchukin, Dmitry G.
A1  - Gorin, Dmitry A.
A1  - Kopyshev, Alexey
A1  - Moehwald, Helmuth
T1  - A new approach to nucleation of cavitation bubbles at chemically modified surfaces
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - Cavitation at the solid surface normally begins with nucleation, in which defects or assembled molecules located at a liquid-solid interface act as nucleation centers and are actively involved in the evolution of cavitation bubbles. Here, we propose a simple approach to evaluate the behavior of cavitation bubbles formed under high intensity ultrasound (20 kHz, 51.3 W cm (2)) at solid surfaces, based on sonication of patterned substrates with a small roughness (less than 3 nm) and controllable surface energy. A mixture of octadecylphosphonic acid (ODTA) and octadecanethiol (ODT) was stamped on the Si wafer coated with different thicknesses of an aluminium layer (20-500 nm). We investigated the growth mechanism of cavitation bubble nuclei and the evolution of individual pits (defects) formed under sonication on the modified surface. A new activation behavior as a function of Al thickness, sonication time, ultrasonic power and temperature is reported. In this process cooperativity is introduced, as initially formed pits further reduce the energy to form bubbles. Furthermore, cavitation on the patterns is a controllable process, where up to 40-50 min of sonication time only the hydrophobic areas are active nucleation sites. This study provides a convincing proof of our theoretical approach on nucleation.
Y1  - 2011
U6  - https://doi.org/10.1039/c1cp20218a
SN  - 1463-9076
VL  - 13
IS  - 17
SP  - 8015
EP  - 8023
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Kiel, Mareike
A1  - Möhwald, Helmuth
A1  - Bargheer, Matias
T1  - Broadband measurements of the transient optical complex dielectric function of a nanoparticle/polymer composite upon ultrafast excitation
JF  - Physical review : B, Condensed matter and materials physics
N2  - We determined experimentally the complex transient optical dielectric function of a well-characterized polyelectrolyte/gold-nanoparticle composite system over a broad spectral range upon short pulse laser excitation by simultaneously measuring the time-dependent reflectance and transmittance of white light pulses with femtosecond pump-probe spectroscopy. We extracted directly the ultrafast changes in the real and imaginary parts of the effective dielectric function, epsilon(eff)(r) (omega,t)and epsilon(eff)(i) (omega,t), from the experiment. This complete experimental set of information on the time-dependent complex dielectric function challenges theories modeling the transient dielectric function of gold particles and the effective medium.
Y1  - 2011
U6  - https://doi.org/10.1103/PhysRevB.84.165121
SN  - 1098-0121
VL  - 84
IS  - 16
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Actis, M.
A1  - Agnetta, G.
A1  - Aharonian, Felix A.
A1  - Akhperjanian, A. G.
A1  - Aleksic, J.
A1  - Aliu, E.
A1  - Allan, D.
A1  - Allekotte, I.
A1  - Antico, F.
A1  - Antonelli, L. A.
A1  - Antoranz, P.
A1  - Aravantinos, A.
A1  - Arlen, T.
A1  - Arnaldi, H.
A1  - Artmann, S.
A1  - Asano, K.
A1  - Asorey, H. G.
A1  - Baehr, J.
A1  - Bais, A.
A1  - Baixeras, C.
A1  - Bajtlik, S.
A1  - Balis, D.
A1  - Bamba, A.
A1  - Barbier, C.
A1  - Barcelo, M.
A1  - Barnacka, Anna
A1  - Barnstedt, Jürgen
A1  - de Almeida, U. Barres
A1  - Barrio, J. A.
A1  - Basso, S.
A1  - Bastieri, D.
A1  - Bauer, C.
A1  - Becerra Gonzalez, J.
A1  - Becherini, Yvonne
A1  - Bechtol, K. C.
A1  - Becker, J.
A1  - Beckmann, Volker
A1  - Bednarek, W.
A1  - Behera, B.
A1  - Beilicke, M.
A1  - Belluso, M.
A1  - Benallou, M.
A1  - Benbow, W.
A1  - Berdugo, J.
A1  - Berger, K.
A1  - Bernardino, T.
A1  - Bernlöhr, K.
A1  - Biland, A.
A1  - Billotta, S.
A1  - Bird, T.
A1  - Birsin, E.
A1  - Bissaldi, E.
A1  - Blake, S.
A1  - Blanch Bigas, O.
A1  - Bobkov, A. A.
A1  - Bogacz, L.
A1  - Bogdan, M.
A1  - Boisson, Catherine
A1  - Boix Gargallo, J.
A1  - Bolmont, J.
A1  - Bonanno, G.
A1  - Bonardi, A.
A1  - Bonev, T.
A1  - Borkowski, Janett
A1  - Botner, O.
A1  - Bottani, A.
A1  - Bourgeat, M.
A1  - Boutonnet, C.
A1  - Bouvier, A.
A1  - Brau-Nogue, S.
A1  - Braun, I.
A1  - Bretz, T.
A1  - Briggs, M. S.
A1  - Brun, Pierre
A1  - Brunetti, L.
A1  - Buckley, H.
A1  - Bugaev, V.
A1  - Buehler, R.
A1  - Bulik, Tomasz
A1  - Busetto, G.
A1  - Buson, S.
A1  - Byrum, K.
A1  - Cailles, M.
A1  - Cameron, R. A.
A1  - Canestrari, R.
A1  - Cantu, S.
A1  - Carmona, E.
A1  - Carosi, A.
A1  - Carr, John
A1  - Carton, P. H.
A1  - Casiraghi, M.
A1  - Castarede, H.
A1  - Catalano, O.
A1  - Cavazzani, S.
A1  - Cazaux, S.
A1  - Cerruti, B.
A1  - Cerruti, M.
A1  - Chadwick, M.
A1  - Chiang, J.
A1  - Chikawa, M.
A1  - Cieslar, M.
A1  - Ciesielska, M.
A1  - Cillis, A. N.
A1  - Clerc, C.
A1  - Colin, P.
A1  - Colome, J.
A1  - Compin, M.
A1  - Conconi, P.
A1  - Connaughton, V.
A1  - Conrad, Jan
A1  - Contreras, J. L.
A1  - Coppi, P.
A1  - Corlier, M.
A1  - Corona, P.
A1  - Corpace, O.
A1  - Corti, D.
A1  - Cortina, J.
A1  - Costantini, H.
A1  - Cotter, G.
A1  - Courty, B.
A1  - Couturier, S.
A1  - Covino, S.
A1  - Croston, J.
A1  - Cusumano, G.
A1  - Daniel, M. K.
A1  - Dazzi, F.
A1  - Deangelis, A.
A1  - de Cea del Pozo, E.
A1  - Dal Pino, E. M. de Gouveia
A1  - de Jager, O.
A1  - de la Calle Perez, I.
A1  - De La Vega, G.
A1  - De Lotto, B.
A1  - de Naurois, M.
A1  - Wilhelmi, E. de Ona
A1  - de Souza, V.
A1  - Decerprit, B.
A1  - Deil, C.
A1  - Delagnes, E.
A1  - Deleglise, G.
A1  - Delgado, C.
A1  - Dettlaff, T.
A1  - Di Paolo, A.
A1  - Di Pierro, F.
A1  - Diaz, C.
A1  - Dick, J.
A1  - Dickinson, H.
A1  - Digel, S. W.
A1  - Dimitrov, D.
A1  - Disset, G.
A1  - Djannati-Ataï, A.
A1  - Doert, M.
A1  - Domainko, W.
A1  - Dorner, D.
A1  - Doro, M.
A1  - Dournaux, J. -L.
A1  - Dravins, D.
A1  - Drury, L.
A1  - Dubois, F.
A1  - Dubois, R.
A1  - Dubus, G.
A1  - Dufour, C.
A1  - Durand, D.
A1  - Dyks, J.
A1  - Dyrda, M.
A1  - Edy, E.
A1  - Egberts, Kathrin
A1  - Eleftheriadis, C.
A1  - Elles, S.
A1  - Emmanoulopoulos, D.
A1  - Enomoto, R.
A1  - Ernenwein, J. -P.
A1  - Errando, M.
A1  - Etchegoyen, A.
A1  - Falcone, A. D.
A1  - Farakos, K.
A1  - Farnier, C.
A1  - Federici, S.
A1  - Feinstein, F.
A1  - Ferenc, D.
A1  - Fillin-Martino, E.
A1  - Fink, D.
A1  - Finley, C.
A1  - Finley, J. P.
A1  - Firpo, R.
A1  - Florin, D.
A1  - Foehr, C.
A1  - Fokitis, E.
A1  - Font, Ll.
A1  - Fontaine, G.
A1  - Fontana, A.
A1  - Foerster, A.
A1  - Fortson, L.
A1  - Fouque, N.
A1  - Fransson, C.
A1  - Fraser, G. W.
A1  - Fresnillo, L.
A1  - Fruck, C.
A1  - Fujita, Y.
A1  - Fukazawa, Y.
A1  - Funk, S.
A1  - Gaebele, W.
A1  - Gabici, S.
A1  - Gadola, A.
A1  - Galante, N.
A1  - Gallant, Y.
A1  - Garcia, B.
A1  - Garcia Lopez, R. J.
A1  - Garrido, D.
A1  - Garrido, L.
A1  - Gascon, D.
A1  - Gasq, C.
A1  - Gaug, M.
A1  - Gaweda, J.
A1  - Geffroy, N.
A1  - Ghag, C.
A1  - Ghedina, A.
A1  - Ghigo, M.
A1  - Gianakaki, E.
A1  - Giarrusso, S.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Giro, E.
A1  - Giubilato, P.
A1  - Glanzman, T.
A1  - Glicenstein, J. -F.
A1  - Gochna, M.
A1  - Golev, V.
A1  - Gomez Berisso, M.
A1  - Gonzalez, A.
A1  - Gonzalez, F.
A1  - Granena, F.
A1  - Graciani, R.
A1  - Granot, J.
A1  - Gredig, R.
A1  - Green, A.
A1  - Greenshaw, T.
A1  - Grimm, O.
A1  - Grube, J.
A1  - Grudzinska, M.
A1  - Grygorczuk, J.
A1  - Guarino, V.
A1  - Guglielmi, L.
A1  - Guilloux, F.
A1  - Gunji, S.
A1  - Gyuk, G.
A1  - Hadasch, D.
A1  - Haefner, D.
A1  - Hagiwara, R.
A1  - Hahn, J.
A1  - Hallgren, A.
A1  - Hara, S.
A1  - Hardcastle, M. J.
A1  - Hassan, T.
A1  - Haubold, T.
A1  - Hauser, M.
A1  - Hayashida, M.
A1  - Heller, R.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Herrero, A.
A1  - Hinton, James Anthony
A1  - Hoffmann, D.
A1  - Hofmann, W.
A1  - Hofverberg, P.
A1  - Horns, D.
A1  - Hrupec, D.
A1  - Huan, H.
A1  - Huber, B.
A1  - Huet, J. -M.
A1  - Hughes, G.
A1  - Hultquist, K.
A1  - Humensky, T. B.
A1  - Huppert, J. -F.
A1  - Ibarra, A.
A1  - Illa, J. M.
A1  - Ingjald, J.
A1  - Inoue, S.
A1  - Inoue, Y.
A1  - Ioka, K.
A1  - Jablonski, C.
A1  - Jacholkowska, A.
A1  - Janiak, M.
A1  - Jean, P.
A1  - Jensen, H.
A1  - Jogler, T.
A1  - Jung, I.
A1  - Kaaret, P.
A1  - Kabuki, S.
A1  - Kakuwa, J.
A1  - Kalkuhl, C.
A1  - Kankanyan, R.
A1  - Kapala, M.
A1  - Karastergiou, A.
A1  - Karczewski, M.
A1  - Karkar, S.
A1  - Karlsson, N.
A1  - Kasperek, J.
A1  - Katagiri, H.
A1  - Katarzynski, K.
A1  - Kawanaka, N.
A1  - Kedziora, B.
A1  - Kendziorra, E.
A1  - Khelifi, B.
A1  - Kieda, D.
A1  - Kifune, T.
A1  - Kihm, T.
A1  - Klepser, S.
A1  - Kluzniak, W.
A1  - Knapp, J.
A1  - Knappy, A. R.
A1  - Kneiske, T.
A1  - Knoedlseder, J.
A1  - Koeck, F.
A1  - Kodani, K.
A1  - Kohri, K.
A1  - Kokkotas, K.
A1  - Komin, N.
A1  - Konopelko, A.
A1  - Kosack, K.
A1  - Kossakowski, R.
A1  - Kostka, P.
A1  - Kotula, J.
A1  - Kowal, G.
A1  - Koziol, J.
A1  - Kraehenbuehl, T.
A1  - Krause, J.
A1  - Krawczynski, H.
A1  - Krennrich, F.
A1  - Kretzschmann, A.
A1  - Kubo, H.
A1  - Kudryavtsev, V. A.
A1  - Kushida, J.
A1  - La Barbera, N.
A1  - La Parola, V.
A1  - La Rosa, G.
A1  - Lopez, A.
A1  - Lamanna, G.
A1  - Laporte, P.
A1  - Lavalley, C.
A1  - Le Flour, T.
A1  - Le Padellec, A.
A1  - Lenain, J. -P.
A1  - Lessio, L.
A1  - Lieunard, B.
A1  - Lindfors, E.
A1  - Liolios, A.
A1  - Lohse, T.
A1  - Lombardi, S.
A1  - Lopatin, A.
A1  - Lorenz, E.
A1  - Lubinski, P.
A1  - Luz, O.
A1  - Lyard, E.
A1  - Maccarone, M. C.
A1  - Maccarone, T.
A1  - Maier, G.
A1  - Majumdar, P.
A1  - Maltezos, S.
A1  - Malkiewicz, P.
A1  - Mana, C.
A1  - Manalaysay, A.
A1  - Maneva, G.
A1  - Mangano, A.
A1  - Manigot, P.
A1  - Marin, J.
A1  - Mariotti, M.
A1  - Markoff, S.
A1  - Martinez, G.
A1  - Martinez, M.
A1  - Mastichiadis, A.
A1  - Matsumoto, H.
A1  - Mattiazzo, S.
A1  - Mazin, D.
A1  - McComb, T. J. L.
A1  - McCubbin, N.
A1  - McHardy, I.
A1  - Medina, C.
A1  - Melkumyan, D.
A1  - Mendes, A.
A1  - Mertsch, P.
A1  - Meucci, M.
A1  - Michalowski, J.
A1  - Micolon, P.
A1  - Mineo, T.
A1  - Mirabal, N.
A1  - Mirabel, F.
A1  - Miranda, J. M.
A1  - Mirzoyan, R.
A1  - Mizuno, T.
A1  - Moal, B.
A1  - Moderski, R.
A1  - Molinari, E.
A1  - Monteiro, I.
A1  - Moralejo, A.
A1  - Morello, C.
A1  - Mori, K.
A1  - Motta, G.
A1  - Mottez, F.
A1  - Moulin, Emmanuel
A1  - Mukherjee, R.
A1  - Munar, P.
A1  - Muraishi, H.
A1  - Murase, K.
A1  - Murphy, A. Stj.
A1  - Nagataki, S.
A1  - Naito, T.
A1  - Nakamori, T.
A1  - Nakayama, K.
A1  - Naumann, C. L.
A1  - Naumann, D.
A1  - Nayman, P.
A1  - Nedbal, D.
A1  - Niedzwiecki, A.
A1  - Niemiec, J.
A1  - Nikolaidis, A.
A1  - Nishijima, K.
A1  - Nolan, S. J.
A1  - Nowak, N.
A1  - O'Brien, P. T.
A1  - Ochoa, I.
A1  - Ohira, Y.
A1  - Ohishi, M.
A1  - Ohka, H.
A1  - Okumura, A.
A1  - Olivetto, C.
A1  - Ong, R. A.
A1  - Orito, R.
A1  - Orr, M.
A1  - Osborne, J. P.
A1  - Ostrowski, M.
A1  - Otero, L.
A1  - Otte, A. N.
A1  - Ovcharov, E.
A1  - Oya, I.
A1  - Ozieblo, A.
A1  - Paiano, S.
A1  - Pallota, J.
A1  - Panazol, J. L.
A1  - Paneque, D.
A1  - Panter, M.
A1  - Paoletti, R.
A1  - Papyan, G.
A1  - Paredes, J. M.
A1  - Pareschi, G.
A1  - Parsons, R. D.
A1  - Arribas, M. Paz
A1  - Pedaletti, G.
A1  - Pepato, A.
A1  - Persic, M.
A1  - Petrucci, P. O.
A1  - Peyaud, B.
A1  - Piechocki, W.
A1  - Pita, S.
A1  - Pivato, G.
A1  - Platos, L.
A1  - Platzer, R.
A1  - Pogosyan, L.
A1  - Pohl, Martin
A1  - Pojmanski, G.
A1  - Ponz, J. D.
A1  - Potter, W.
A1  - Prandini, E.
A1  - Preece, R.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quel, E.
A1  - Quirrenbach, A.
A1  - Rajda, P.
A1  - Rando, R.
A1  - Rataj, M.
A1  - Raue, M.
A1  - Reimann, C.
A1  - Reimann, O.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - Renner, S.
A1  - Reymond, J. -M.
A1  - Rhode, W.
A1  - Ribo, M.
A1  - Ribordy, M.
A1  - Rico, J.
A1  - Rieger, F.
A1  - Ringegni, P.
A1  - Ripken, J.
A1  - Ristori, P.
A1  - Rivoire, S.
A1  - Rob, L.
A1  - Rodriguez, S.
A1  - Roeser, U.
A1  - Romano, Patrizia
A1  - Romero, G. E.
A1  - Rosier-Lees, S.
A1  - Rovero, A. C.
A1  - Roy, F.
A1  - Royer, S.
A1  - Rudak, B.
A1  - Rulten, C. B.
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A1  - Santangelo, Andrea
A1  - Santos, E. M.
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A1  - Sapozhnikov, L.
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A1  - Scalzotto, V.
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A1  - Scarcioffolo, M.
A1  - Schanz, T.
A1  - Schlenstedt, S.
A1  - Schlickeiser, R.
A1  - Schmidt, T.
A1  - Schmoll, J.
A1  - Schroedter, M.
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A1  - Schultze, J.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwarzburg, S.
A1  - Schweizer, T.
A1  - Seiradakis, J.
A1  - Selmane, S.
A1  - Seweryn, K.
A1  - Shayduk, M.
A1  - Shellard, R. C.
A1  - Shibata, T.
A1  - Sikora, M.
A1  - Silk, J.
A1  - Sillanpaa, A.
A1  - Sitarek, J.
A1  - Skole, C.
A1  - Smith, N.
A1  - Sobczynska, D.
A1  - Sofo Haro, M.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spiga, D.
A1  - Spyrou, S.
A1  - Stamatescu, V.
A1  - Stamerra, A.
A1  - Starling, R. L. C.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steiner, S.
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T1  - Design concepts for the Cherenkov Telescope Array CTA an advanced facility for ground-based high-energy gamma-ray astronomy
JF  - Experimental astronomy : an international journal on astronomical instrumentation and data analysis
N2  - Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.
KW  - Ground based gamma ray astronomy
KW  - Next generation Cherenkov telescopes
KW  - Design concepts
Y1  - 2011
U6  - https://doi.org/10.1007/s10686-011-9247-0
SN  - 0922-6435
SN  - 1572-9508
VL  - 32
IS  - 3
SP  - 193
EP  - 316
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Winkelmann, Ricarda
A1  - Martin, Maria A.
A1  - Haseloff, Monika
A1  - Albrecht, Torsten
A1  - Bueler, Ed
A1  - Khroulev, C.
A1  - Levermann, Anders
T1  - The Potsdam parallel ice sheet model (PISM-PIK) - Part 1: Model description
JF  - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2  - We present the Potsdam Parallel Ice Sheet Model (PISM-PIK), developed at the Potsdam Institute for Climate Impact Research to be used for simulations of large-scale ice sheet-shelf systems. It is derived from the Parallel Ice Sheet Model (Bueler and Brown, 2009). Velocities are calculated by superposition of two shallow stress balance approximations within the entire ice covered region: the shallow ice approximation (SIA) is dominant in grounded regions and accounts for shear deformation parallel to the geoid. The plug-flow type shallow shelf approximation (SSA) dominates the velocity field in ice shelf regions and serves as a basal sliding velocity in grounded regions. Ice streams can be identified diagnostically as regions with a significant contribution of membrane stresses to the local momentum balance. All lateral boundaries in PISM-PIK are free to evolve, including the grounding line and ice fronts. Ice shelf margins in particular are modeled using Neumann boundary conditions for the SSA equations, reflecting a hydrostatic stress imbalance along the vertical calving face. The ice front position is modeled using a subgrid-scale representation of calving front motion (Albrecht et al., 2011) and a physically-motivated calving law based on horizontal spreading rates. The model is tested in experiments from the Marine Ice Sheet Model Intercomparison Project (MISMIP). A dynamic equilibrium simulation of Antarctica under present-day conditions is presented in Martin et al. (2011).
Y1  - 2011
U6  - https://doi.org/10.5194/tc-5-715-2011
SN  - 1994-0416
VL  - 5
IS  - 3
SP  - 715
EP  - 726
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Martin, Maria A.
A1  - Winkelmann, Ricarda
A1  - Haseloff, M.
A1  - Albrecht, Tanja
A1  - Bueler, Ed
A1  - Khroulev, C.
A1  - Levermann, Anders
T1  - The Potsdam parallel ice sheet model (PISM-PIK) - Part 2: Dynamic equilibrium simulation of the Antarctic ice sheet
JF  - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2  - We present a dynamic equilibrium simulation of the ice sheet-shelf system on Antarctica with the Potsdam Parallel Ice Sheet Model (PISM-PIK). The simulation is initialized with present-day conditions for bed topography and ice thickness and then run to steady state with constant present-day surface mass balance. Surface temperature and sub-shelf basal melt distribution are parameterized. Grounding lines and calving fronts are free to evolve, and their modeled equilibrium state is compared to observational data. A physically-motivated calving law based on horizontal spreading rates allows for realistic calving fronts for various types of shelves. Steady-state dynamics including surface velocity and ice flux are analyzed for whole Antarctica and the Ronne-Filchner and Ross ice shelf areas in particular. The results show that the different flow regimes in sheet and shelves, and the transition zone between them, are captured reasonably well, supporting the approach of superposition of SIA and SSA for the representation of fast motion of grounded ice. This approach also leads to a natural emergence of sliding-dominated flow in stream-like features in this new 3-D marine ice sheet model.
Y1  - 2011
U6  - https://doi.org/10.5194/tc-5-727-2011
SN  - 1994-0416
VL  - 5
IS  - 3
SP  - 727
EP  - 740
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Oskinova, Lidia M.
A1  - Todt, Helge Tobias
A1  - Ignace, Richard
A1  - Brown, John C.
A1  - Cassinelli, Joseph P.
A1  - Hamann, Wolf-Rainer
T1  - Early magnetic B-type stars X-ray emission and wind properties
JF  - Monthly notices of the Royal Astronomical Society
N2  - We present a comprehensive study of X-ray emission by, and wind properties of, massive magnetic early B-type stars. Dedicated XMM-Newton observations were obtained for three early-type B-type stars, xi(1) CMa, V2052 Oph and zeta Cas, with recently discovered magnetic fields. We report the first detection of X-ray emission from V2052 Oph and zeta Cas. The latter is one the softest X-ray sources among the early-type stars, while the former is one of the X-ray faintest. The observations show that the X-ray spectra of our programme stars are quite soft with the bulk of X-ray emitting material having a temperature of about 1 MK. We compile the complete sample of early B-type stars with detected magnetic fields to date and existing X-ray measurements, in order to study whether the X-ray emission can be used as a general proxy for stellar magnetism. We find that the X-ray properties of early massive B-type magnetic stars are diverse, and that hard and strong X-ray emission does not necessarily correlate with the presence of a magnetic field, corroborating similar conclusions reached earlier for the classical chemically peculiar magnetic Bp-Ap stars.
 We analyse the ultraviolet (UV) spectra of five non-supergiant B stars with magnetic fields (tau Sco, beta Cep, xi(1) CMa, V2052 Oph and zeta Cas) by means of non-local thermodynamic equilibrium (non-LTE) iron-blanketed model atmospheres. The latter are calculated with the Potsdam Wolf-Rayet (PoWR) code, which treats the photosphere as well as the wind, and also accounts for X-rays. With the exception of t Sco, this is the first analysis of these stars by means of stellar wind models. Our models accurately fit the stellar photospheric spectra in the optical and the UV. The parameters of X-ray emission, temperature and flux are included in the model in accordance with observations. We confirm the earlier findings that the filling factors of X-ray emitting material are very high.
 Our analysis reveals that the magnetic early-type B stars studied here have weak winds with velocities not significantly exceeding upsilon(esc). The mass-loss rates inferred from the analysis of UV lines are significantly lower than predicted by hydrodynamically consistent models. We find that, although the X-rays strongly affect the ionization structure of the wind, this effect is not sufficient in reducing the total radiative acceleration. When the X-rays are accounted for at the intensity and temperatures observed, there is still sufficient radiative acceleration to drive a stronger mass-loss than we empirically infer from the UV spectral lines.
KW  - techniques: spectroscopic
KW  - stars: magnetic field
KW  - stars: massive
KW  - stars: mass loss
KW  - X-rays: stars
Y1  - 2011
U6  - https://doi.org/10.1111/j.1365-2966.2011.19143.x
SN  - 0035-8711
VL  - 416
IS  - 2
SP  - 1456
EP  - 1474
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -