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6 results on '"Fakultät für Physik [Garching]"'

1. Experimental realization of dynamic fluence field optimization for proton computed tomography

Author

Mark Pankuch, Christina Sarosiek, Guillaume Landry, V. Rykalin, Reinhard W. Schulte, Jannis Dickmann, Katia Parodi, George Coutrakon, Nicholas Detrich, Simon Rit, R. P. Johnson, Georgios Dedes, Fakultät für Physik [Garching], Ludwig-Maximilians-Universität München (LMU), Northern Illinois University, Northwestern Medicine [Chicago, IL, États-Unis], ProtonVDA Inc. [Naperville, IL, USA], Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Ion Beam Applications SA [Louvain-La-Neuve, Belgium], IBA, University of California [Santa Cruz] (UCSC), University of California, Loma Linda University, Ludwig Maximilian University [Munich] (LMU), German Cancer Consortium [Munich, Germany] ( Partner Sites), Rit, Simon, Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), University of California [Santa Cruz] (UC Santa Cruz), and University of California (UC)

Subjects
Noise map, Monte Carlo method, Radiotherapy Planning, Clinical Sciences, [INFO.INFO-IM] Computer Science [cs]/Medical Imaging, Biomedical Engineering, dynamic fluence modulation, relative stopping power, Bioengineering, Fluence, Phantoms, 030218 nuclear medicine & medical imaging, Imaging, 03 medical and health sciences, 0302 clinical medicine, Optics, Computer-Assisted, Clinical Research, Image noise, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, proton therapy, Humans, Radiology, Nuclear Medicine and imaging, Radiation treatment planning, proton CT, Proton therapy, Tomography, Physics, Radiological and Ultrasound Technology, Phantoms, Imaging, business.industry, Radiotherapy Planning, Computer-Assisted, Pencil (optics), X-Ray Computed, Other Physical Sciences, Nuclear Medicine & Medical Imaging, Beamline, dose reduction, 030220 oncology & carcinogenesis, Biomedical Imaging, Tomography, X-Ray Computed, business, Monte Carlo Method, Algorithms
Abstract

Proton computed tomography (pCT) has high accuracy and dose efficiency in producing spatial maps of the relative stopping power (RSP) required for treatment planning in proton therapy. With fluence-modulated pCT (FMpCT), prescribed noise distributions can be achieved, which allows to decrease imaging dose by employing object-specific dynamically modulated fluence during the acquisition. For FMpCT acquisitions we divide the image into region-of-interest (ROI) and non-ROI volumes. In proton therapy, the ROI volume would encompass all treatment beams. An optimization algorithm then calculates dynamically modulated fluence that achieves low prescribed noise inside the ROI and high prescribed noise elsewhere. It also produces a planned noise distribution, which is the expected noise map for that fluence, as calculated with a Monte Carlo simulation. The optimized fluence can be achieved by acquiring pCT images with grids of intensity modulated pencil beams. In this work, we interfaced the control system of a clinical proton beam line to deliver the optimized fluence. Using three phantoms we acquired images with uniform fluence, with a constant noise prescription, and with an FMpCT task. Image noise distributions as well as fluence maps were compared to the corresponding planned distributions as well as to the prescription. Furthermore, we propose a correction method that removes image artifacts stemming from the acquisition with pencil beams having a spatially varying energy distribution that is not seen in clinical operation. RSP accuracy of FMpCT scans was compared to uniform scans and was found to be comparable to standard pCT scans. While we identified technical improvements for future experimental acquisitions, in particular related to an unexpected pencil beam size reduction and a misalignment of the fluence pattern, agreement with the planned noise was satisfactory and we conclude that FMpCT optimized for specific image noise prescriptions is experimentally feasible.

Published
2020
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2. Sub-cycle temporal evolution of light-induced electron dynamics in hexagonal 2D materials

Author

Christian Heide, Takuya Higuchi, Tobias Boolakee, Peter Hommelhoff, Fakultät für Physik [Garching], and Ludwig-Maximilians-Universität München (LMU)

Subjects
Materials science, Band gap, Population, FOS: Physical sciences, 02 engineering and technology, Electron, Optical field, 01 natural sciences, law.invention, law, Dispersion relation, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, ddc:530, [NLIN]Nonlinear Sciences [physics], Electrical and Electronic Engineering, 010306 general physics, education, ComputingMilieux_MISCELLANEOUS, education.field_of_study, Valence (chemistry), Condensed matter physics, Condensed Matter - Mesoscale and Nanoscale Physics, Graphene, 021001 nanoscience & nanotechnology, Atomic and Molecular Physics, and Optics, Transition metal dichalcogenide monolayers, Electronic, Optical and Magnetic Materials, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], 0210 nano-technology, Optics (physics.optics), Physics - Optics
Abstract

Two-dimensional materials with hexagonal symmetry such as graphene and transition metal dichalcogenides are unique materials to study light-field-controlled electron dynamics inside of a solid. Around the K-point, the dispersion relation represents an ideal system to study intricately coupled intraband motion and interband (Landau-Zener) transitions driven by the optical field of phase-controlled few-cycle laser pulses. Based on the coupled nature of the intraband and interband processes, we have recently observed in graphene repeated coherent Landau-Zener transitions between valence and conduction band separated by around half an optical period of ∼1.3 fs (Higuchi et al Nature 550, 224 (2017)). Due to the low temporal symmetry of the applied laser pulse, a residual current density and a net electron polarization are formed. Here we show extended numerical data on the temporal evolution of the conduction band population of 2D materials with hexagonal symmetry during the light–matter interaction, yielding deep insights to attosecond-fast electron dynamics. In addition, we show that a residual ballistic current density is formed, which strongly increases when a band gap is introduced. Both, the sub-cycle electron dynamics and the resulting residual current are relevant for the fundamental understanding and future applications of strongly driven electrons in two-dimensional materials, including graphene or transition metal dichalcogenide monolayers.

Published
2020
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3. Attosecond-fast internal photoemission

Author

Takuya Higuchi, Lothar Ley, Peter Hommelhoff, Christian Heide, Jürgen Ristein, Martin Hauck, Heiko B. Weber, Lehrstuhl für Technische Physik, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Fakultät für Physik [Garching], Ludwig-Maximilians-Universität München (LMU), European Project: 712590,H2020 FET Open 'Technologies futures et émergentes',829153,PETACom(2019), and European Project: 616823,EC:FP7:ERC,ERC-2013-CoG,NEARFIELDATTO(2014)

Subjects
Materials science, Schottky barrier, Attosecond, FOS: Physical sciences, 02 engineering and technology, Electron, Applied Physics (physics.app-ph), 7. Clean energy, 01 natural sciences, law.invention, 010309 optics, law, 0103 physical sciences, Condensed Matter - Materials Science, business.industry, Graphene, Materials Science (cond-mat.mtrl-sci), Physics - Applied Physics, Photoelectric effect, 021001 nanoscience & nanotechnology, Atomic and Molecular Physics, and Optics, Semimetal, Electronic, Optical and Magnetic Materials, Semiconductor, Femtosecond, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Optoelectronics, 0210 nano-technology, business
Abstract

The photoelectric effect has a sister process relevant in optoelectronics called internal photoemission1–3. Here an electron is photoemitted from a metal into a semiconductor4,5. While the photoelectric effect takes place within less than 100 attoseconds (1 as = 10−18 seconds)6,7, the attosecond timescale has so far not been measured for internal photoemission. Based on the new method CHArge transfer time MEasurement via Laser pulse duration-dependent saturation fluEnce determinatiON—CHAMELEON—we show that the atomically thin semimetal graphene coupled to bulk silicon carbide, forming a Schottky junction, allows charge transfer times as fast as (300 ± 200) as. These results are supported by a simple quantum mechanical model simulation. With the obtained cut-off bandwidth of 3.3 PHz (1 PHz = 1015 Hz) for the charge transfer rate, this semimetal/semiconductor interface represents a functional solid-state interface offering the speed and design space required for future light-wave signal processing. Femtosecond laser pulses are sent to a graphene/SiC interface to investigate photoinduced charge transfer from graphene to SiC. A charge transfer time of 300 attoseconds is obtained via laser-pulse-duration-dependent saturation fluence determination.

Published
2020
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4. The quantum technologies roadmap: a European community view

Author

Acín, Antonio, Bloch, Immanuel, Buhrman, Harry, Calarco, Tommaso, Eichler, Christopher, Eisert, Jens, Esteve, Daniel, Gisin, Nicolas, Glaser, Steffen J., Jelezko, Fedor, Kuhr, Stefan, Lewenstein, Maciej, Riedel, Max F., Schmidt, Piet O., Thew, Rob, Wallraff, Andreas, Walmsley, Ian, Wilhelm, Frank K., Institut de Ciencies Fotoniques [Castelldefels] (ICFO), QUANTUM (QUANTUM), Johannes Gutenberg - Universität Mainz (JGU), Fakultät für Physik [Garching], Ludwig-Maximilians-Universität München (LMU), Centrum voor Wiskunde en Informatica (CWI), Centrum Wiskunde & Informatica (CWI)-Netherlands Organisation for Scientific Research, Institute for Quantum Information Processing, Universität Ulm - Ulm University [Ulm, Allemagne], Institute of Quantum Electronics [ETH Zürich] (IQE), Department of Physics [ETH Zürich] (D-PHYS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Freie Universität Berlin, Quantronics Group (QUANTRONICS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Group of Applied Physics [Geneva] (GAP), University of Geneva [Switzerland], Department of Chemistry [Munich], Technische Universität Munchen - Université Technique de Munich [Munich, Allemagne] (TUM), Stuttgart University, Laboratoire Kastler Brossel (LKB (Lhomond)), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut für Theoretische Physik [Hannover] (ITP), Leibniz Universität Hannover [Hannover] (LUH), Physikalisch-Technische Bundesanstalt [Braunschweig] (PTB), Department of Physics, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Clarendon Laboratory [Oxford], University of Oxford [Oxford], Saarland University [Saarbrücken], Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University (JGU), Université de Genève = University of Geneva (UNIGE), Universität Stuttgart [Stuttgart], École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Leibniz Universität Hannover=Leibniz University Hannover, and University of Oxford

Subjects
Computation theory, Quantum technologies, quantum coomputing, ddc:500.2, Quantum entanglement, Quantum cryptography, Quantum simulations, Quantum electronics, ddc:530, Quantum communication, ComputingMilieux_MISCELLANEOUS, Quantenkommunikation, [PHYS]Physics [physics], Quantum optics, DDC 530 / Physics, Quantum sensing, Quantentheorie, quantum theory, quantum simulation, quantum sensing, quantum communication, quantum technologies, quantum control, Quantum computers, Quantum control, Quantum computing, Quantum theory, Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik, Quantum simulation, Quantum chemistry, Quantencomputer
Abstract

Within the last two decades, quantum technologies (QT) have made tremendous progress, moving from Nobel Prize award-winning experiments on quantum physics (1997: Chu, Cohen-Tanoudji, Phillips; 2001: Cornell, Ketterle, Wieman; 2005: Hall, Hänsch-, Glauber; 2012: Haroche, Wineland) into a cross-disciplinary field of applied research. Technologies are being developed now that explicitly address individual quantum states and make use of the 'strange' quantum properties, such as superposition and entanglement. The field comprises four domains: quantum communication, where individual or entangled photons are used to transmit data in a provably secure way; quantum simulation, where well-controlled quantum systems are used to reproduce the behaviour of other, less accessible quantum systems; quantum computation, which employs quantum effects to dramatically speed up certain calculations, such as number factoring; and quantum sensing and metrology, where the high sensitivity of coherent quantum systems to external perturbations is exploited to enhance the performance of measurements of physical quantities. In Europe, the QT community has profited from several EC funded coordination projects, which, among other things, have coordinated the creation of a 150-page QT Roadmap (http://qurope.eu/h2020/qtflagship/roadmap2016). This article presents an updated summary of this roadmap., New Journal of Physics, 20, ISSN:1367-2630

Published
2018
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5. Search for supernova-produced $^{60}$Fe in a marine sediment

Author

Klaus Knie, Claire Waelbroeck, Grant M. Raisbeck, Stéphane Goriely, Georg Rugel, D. Lunney, Anton Wallner, Caroline Fitoussi, Thomas Faestermann, Gunther Korschinek, Michail Poutivtsev, Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Fakultät für Physik [Garching], Ludwig-Maximilians-Universität München (LMU), Technische Universität Munchen - Université Technique de Munich [Munich, Allemagne] (TUM), Université libre de Bruxelles (ULB), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Universität Wien, and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
Solar System, 97.60.Bw, 26.30.+k, 91.50.-r, FOS: Physical sciences, General Physics and Astronomy, Flux, Astrophysics, 01 natural sciences, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], 0103 physical sciences, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Ejecta, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Astrophysics (astro-ph), Sediment, myr, Crust, Time resolution, Supernova, Oceanography, 13. Climate action, Geology
Abstract

An 60Fe peak in a deep-sea FeMn crust has been interpreted as due to the signature left by the ejecta of a supernova explosion close to the solar system 2.8 +/- 0.4 Myr ago [Knie et al., Phys. Rev. Lett. 93, 171103 (2004)]. To confirm this interpretation with better time resolution and obtain a more direct flux estimate, we measured 60Fe concentrations along a dated marine sediment. We find no 60Fe peak at the expected level from 1.7 to 3.2 Myr ago. However, applying the same chemistry used for the sediment, we confirm the 60Fe signal in the FeMn crust. The cause of the discrepancy is discussed., 15 pages, 5 figures, submitted to PRL

Published
2007
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6. Attosecond imaging of XUV-induced atomic photoemission and Auger decay in strong laser fields

Author

Markus Drescher, O. Herrwerth, Vladislav S. Yakovlev, Irina Znakovskaya, Thorsten Uphues, Matthias F. Kling, Adrian Wirth, Justin Gagnon, Sergey Zherebtsov, Marc J. J. Vrakking, Michael Korbman, Max-Planck-Institut für Quantenoptik (MPQ), Max-Planck-Gesellschaft, Fakultät für Physik [Garching], Ludwig-Maximilians-Universität München (LMU), FOM Institute for Atomic and Molecular Physics (AMOLF), Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Fachbereich für Physik, Universität Hamburg (UHH), Department of Physics [Kansas], and Kansas State University

Subjects
Physics, Auger effect, Attosecond, Far-infrared laser, Electron, Condensed Matter Physics, Laser, 01 natural sciences, Atomic and Molecular Physics, and Optics, Streaking, law.invention, Auger, 010309 optics, symbols.namesake, law, Extreme ultraviolet, Physical Sciences, 0103 physical sciences, Physics::Atomic and Molecular Clusters, symbols, Atomic physics, 010306 general physics
Abstract

International audience; Velocity-map imaging has been employed to study the photoemission in Ne and N 4, 5 OO Auger decay in Xe induced by an isolated 85 eV extreme ultraviolet (XUV) pulse in the presence of a strong few-cycle near-infrared (NIR) laser field. Full three dimensional momentum information about the released electrons was obtained. The NIR and XUV pulse parameters were extracted from the measured Ne streaking traces using a FROG CRAB retrieval algorithm. The attosecond measurements of the Auger decay in Xe show pronounced broadening of the Auger lines corresponding to the formation of sidebands. The temporal evolution of the sideband signals and their asymmetry along the laser polarization axis exhibit oscillations similar to those known from attosecond streaking measurements. The experimental results are in good agreement with model calculations based on an analytical solution of the Schrödinger equation within the strong field approximation.

Published
2011
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