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Defect engineering by Codoping in KCaI3:Eu2+ Single-Crystalline Scintillators

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physical Review Applied 2017年第3期8卷 034011-034011页

作者： Yuntao Wu Qi Li Steven Jones Chaochao Dun Sheng Hu Mariya Zhuravleva Adam C. Lindsey Luis Stand Matthew Loyd Merry Koschan John Auxier, II Howard L. Hall Charles L. Melcher Scintillation Materials Research Center University of Tennessee Knoxville Tennessee 37996 USA Department of Materials Science and Engineering University of Tennessee Knoxville Tennessee 37996 USA Physical Science Division IBM Thomas J Watson Research Center Yorktown Heights New York 10598 USA Department of Computer Science University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA Department of Nuclear Engineering University of Tennessee Knoxville Tennessee 37996 USA Department of Physics Wake Forest University Winston-Salem North Carolina 27109 USA Department of Chemical and Biomolecular Engineering University of Tennessee Knoxville Tennessee 37996 USA

Eu2+-doped alkali or alkali earth iodide scintillators with energy resolutions ≤3% at 662 keV promise the excellent discrimination ability for radioactive isotopes required for homeland-security and nuclear-nonproliferation applications. To extend their applications to x-ray imaging, such as computed tomography scans, the intense afterglow which delays the response time of such materials is an obstacle that needs to be overcome. However, a clear understanding of the origin of the afterglow and feasible solutions is still lacking. In this work, we present a combined experimental and theoretical investigation of the physical insights of codoping-based defect engineering which can reduce the afterglow effectively in KCaI3:Eu2+ single-crystal scintillators. We illustrate that Sc3+ codoping greatly suppresses the afterglow, whereas Y3+, Gd3+, or La3+ codoping enhances the afterglow. Meanwhile, a light yield of 57 000 photons/MeV and an energy resolution of 3.4% at 662 keV can be maintained with the appropriate concentration of Sc3+ codoping, which makes the material promising for medical-imaging applications. Through our thermoluminescence techniques and density-functional-theory calculations, we are able to identify the defect structures and understand the mechanism by which codoping affects the scintillation performance of KCaI3:Eu2+ crystals. The proposed defect-engineering strategy is further validated by achieving afterglow suppression in Mg2+ codoped KCaI3:Eu2+ single crystals.

关键词： Crystal defects Crystal growth Dopants Luminescence Point defects Solid-state detectors Medical imaging Scintillators

Discovery of a Radiation Component from the Vela Pulsar Reaching 20 Teraelectronvolts

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arXiv 2023年

作者： Aharonian, F. Ait Benkhali, F. Aschersleben, J. Ashkar, H. Backes, M. Barbosa Martins, V. Batzofin, R. Becherini, Y. Berge, D. Bernlöhr, K. Bi, B. Böttcher, M. Boisson, C. Bolmont, J. de Bony de Lavergne, M. Borowska, J. Bradascio, F. Breuhaus, M. Brose, R. Brun, F. Bruno, B. Bulik, T. Burger-Scheidlin, C. Bylund, T. Cangemi, F. Caroff, S. Casanova, S. Celic, J. Cerruti, M. Chand, T. Chandra, S. Chen, A. Chibueze, O. Cotter, G. Damascene Mbarubucyeye, J. Djannati-Ataï, A. Dmytriiev, A. Egberts, K. Ernenwein, J.-P. Feijen, K. Fiasson, A. Fichet de Clairfontaine, G. Fontaine, G. Füßling, M. Funk, S. Gabici, S. Gallant, Y.A. Ghafourizadeh, S. Giavitto, G. Giunti, L. Glawion, D. Glicenstein, J.F. Goswami, P. Grolleron, G. Grondin, M.-H. Haerer, L. Haupt, M. Hinton, J.A. Hofmann, W. Holch, T.L. Holler, M. Horns, D. Huang, Zhiqiu Jamrozy, M. Jankowsky, F. Joshi, V. Jung-Richardt, I. Kasai, E. Katarzyński, K. Khélifi, B. Klepser, S. Kluźniak, W. Komin, Nu. Kosack, K. Kostunin, D. Lang, R.G. Le Stum, S. Lemière, A. Lemoine-Goumard, M. Lenain, J.-P. Leuschner, F. Lohse, T. Luashvili, A. Lypova, I. Mackey, J. Malyshev, D. Malyshev, D. Marandon, V. Marchegiani, P. Marcowith, A. Marinos, P. Martí-Devesa, G. Marx, R. Maurin, G. Meyer, M. Mitchell, A. Moderski, R. Mohrmann, L. Montanari, A. Moulin, E. Muller, J. Murach, T. Nakashima, K. de Naurois, M. Niemiec, J. Priyana Noel, A. O’Brien, P. Ohm, S. Olivera-Nieto, L. de Ona Wilhelmi, E. Ostrowski, M. Panny, S. Panter, M. Parsons, R.D. Peron, G. Pita, S. Prokhorov, D.A. Prokoph, H. Pühlhofer, G. Punch, M. Quirrenbach, A. Reichherzer, P. Reimer, A. Reimer, O. Renaud, M. Rieger, F. Rowell, G. Rudak, B. Ruiz-Velasco, E. Sahakian, V. Sailer, S. Salzmann, H. Sanchez, D.A. Santangelo, A. Sasaki, M. Schüssler, F. Schwanke, U. Shapopi, J.N.S. Sinha, A. Sol, H. Specovius, A. Spencer, S. Spir-Jacob, M. Stawarz, L. Steenkamp, R. Steinmassl, S. Steppa, C. Sushch, I. Suzuki, H. Takahashi, T. Tanaka, T. Tavernier, T. Dublin Institute for Advanced Studies 31 Fitzwilliam Place Dublin 2 Ireland Max-Planck-Institut für Kernphysik P.O. Box 103980 HeidelbergD 69029 Germany Landessternwarte Universität Heidelberg Königstuhl HeidelbergD 69117 Germany GRAPPA Anton Pannekoek Institute for Astronomy University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands Laboratoire Leprince-Ringuet École Polytechnique CNRS Institut Polytechnique de Paris PalaiseauF-91128 France University of Namibia Department of Physics Private Bag 13301 Windhoek10005 Namibia Centre for Space Research North-West University Potchefstroom2520 South Africa DESY ZeuthenD-15738 Germany School of Physics University of the Witwatersrand 1 Jan Smuts Avenue Braamfontein Johannesburg2050 South Africa Université de Paris CNRS ParisF-75013 France Department of Physics and Electrical Engineering Linnaeus University Växjö351 95 Sweden Institut für Physik Humboldt-Universität zu Berlin Newtonstr. 15 BerlinD 12489 Germany Institut für Astronomie und Astrophysik Universität Tübingen Sand 1 TübingenD 72076 Germany Laboratoire Univers et Théories Observatoire de Paris Université PSL CNRS Université de Paris Meudon92190 France Sorbonne Université Université Paris Diderot Sorbonne Paris Cité CNRS IN2P3 Laboratoire de Physique Nucléaire et de Hautes Energies LPNHE 4 Place Jussieu ParisF-75252 France Université Savoie Mont Blanc CNRS Laboratoire d’Annecy de Physique des Particules - IN2P3 Annecy74000 France IRFU CEA Université Paris-Saclay Gif-sur-YvetteF-91191 France Friedrich-Alexander-Universität Erlangen-Nürnberg Erlangen Centre for Astroparticle Physics Erwin-Rommel-Str. 1 ErlangenD 91058 Germany Astronomical Observatory The University of Warsaw Al. Ujazdowskie 4 Warsaw00-478 Poland Instytut Fizyki J¸ adrowej PAN ul. Radzikowskiego 152 Kraków31-342 Poland University of Oxford Department of Physics Denys Wilkinson Building Keble Road OxfordOX1 3RH United Kingdom Insti

Gamma-ray observations have established energetic isolated pulsars as outstanding particle accelerators and antimatter factories in the Galaxy. There is, however, no consensus regarding the acceleration mechanisms and the radiative processes at play, nor the locations where these take place. The spectra of all observed gamma-ray pulsars to date show strong cutoffs or a break above energies of a few gigaelectronvolt (GeV). Using the H.E.S.S. array of Cherenkov telescopes, we discovered a novel radiation component emerging beyond this generic GeV cutoff in the Vela pulsar’s broadband spectrum. The extension of gamma-ray pulsation energies up to at least 20 teraelectronvolts (TeV) shows that Vela pulsar can accelerate particles to Lorentz factors higher than 4 × 107. This is an order of magnitude larger than in the case of the Crab pulsar, the only other pulsar detected in the TeV energy range. Our results challenge the state-of-the-art models for high-energy emission of pulsars while providing a new probe, i.e. the energetic multi-TeV component, for constraining the acceleration and emission processes in their extreme energy limit. Copyright © 2023, The Authors. All rights reserved.

关键词： Pulsars

Observation of out-of-plane spin texture in a SrTiO3 (111) two-dimensional electron gas

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arXiv 2018年

作者： He, Pan Walker, S. McKeown Zhang, Steven S.-L. Bruno, F.Y. Bahramy, M.S. Lee, Jongmin Ramaswamy, Rajagopalan Cai, Kaiming Heinonen, Olle Vignale, Giovanni Baumberger, F. Yang, Hyunsoo Department of Electrical and Computer Engineering NUSNNI National University of Singapore 117576 Singapore Department of Quantum Matter Physics University of Geneva 24 Quai Ernest-Ansermet Genève 41211 Switzerland Materials Science Division Argonne National Laboratory LemontIL60439 United States Quantum-Phase Electronics Center Department of Applied Physics University of Tokyo Tokyo113-8656 Japan Wako351-0198 Japan Department of Physics and Astronomy University of Missouri ColumbiaMO65211 United States Swiss Light Source Paul Scherrer Institut Villigen PSICH-5232 Switzerland

We explore the second order bilinear magnetoelectric resistance (BMER) effect in the d-electron-based two-dimensional electron gas (2DEG) at the SrTiO3 (111) surface. We find an evidence of a spin-split band structure with the archetypal spin-momentum locking of the Rashba effect for the in-plane component. Under an out-of-plane magnetic field, we find a BMER signal that breaks the six-fold symmetry of the electronic dispersion, which is a fingerprint for the presence of a momentum dependent out-of-plane spin component. Relativistic electronic structure calculations reproduce this spin-texture and indicate that the out-of-plane component is a ubiquitous property of oxide 2DEGs arising from strong crystal field effects. We further show that the BMER response of the SrTiO3 (111) 2DEG is tunable and unexpectedly large. Copyright © 2018, The Authors. All rights reserved.

关键词： Crystal structure

Machine learning engineering of quantum currents

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arXiv 2019年

作者： Haug, Tobias Dumke, Rainer Kwek, Leong-Chuan Miniatura, Christian Amico, Luigi Centre for Quantum Technologies National University of Singapore 3 Science Drive 2 Singapore117543 Singapore Division of Physics and Applied Physics Nanyang Technological University 21 Nanyang Link Singapore637371 Singapore MajuLab CNRS-UCA-SU-NUS-NTU International Joint Research Unit Singapore School of Electrical and Electronic Engineering 50 Nanyang Ave. Singapore637553 Singapore National Institute of Education Nanyang Technological University 1 Nanyang Walk Singapore637616 Singapore Department of Physics National University of Singapore 2 Science Drive 3 Singapore117542 Singapore School of Physical and Mathematical Sciences Nanyang Technological University Singapore637371 Singapore Yale-NUS College 16 College Avenue West Singapore138527 Singapore Université Côte d'Azur CNRS Institut de Physique de Nice 1361 route des Lucioles Valbonne06560 France Quantum Research Centre Technology Innovation Institute Abu Dhabi United Arab Emirates Dipartimento di Fisica e Astronomia Via S. Sofia 64 Catania95127 Italy CNR-MATIS-IMM INFN-Sezione di Catania Via S. Sofia 64 Catania95127 Italy LANEF'Chaire d'excellence' Universitè Grenoble-Alpes CNRS GrenobleF-38000 France

The design, accurate preparation and manipulation of quantum states in quantum circuits are essential operational tasks at the heart of quantum technologies. Nowadays, circuits can be designed with physical parameters that can be controlled with unprecedented accuracy and flexibility. However, the generation of well-controlled current states is still a nagging bottleneck, especially when different circuit elements are integrated together. In this work, we show how machine learning can effectively address this challenge and outperform the current existing methods. To this end, we exploit deep reinforcement learning to prepare prescribed quantum current states in circuits composed of lumped elements. To highlight our method, we show how to engineer bosonic persistent currents as they are relevant in different quantum technologies as cold atoms and superconducting circuits. We demonstrate the use of deep reinforcement learning to re-discover established protocols, as well as solve configurations that are difficult to treat with other methods. With our approach, quantum current states characterised by a single winding number or entangled currents of multiple winding numbers can be prepared in a robust manner, superseding the existing protocols. Copyright © 2019, The Authors. All rights reserved.

关键词： Deep learning

Resonance Energy Transfer: Utilizing HomoFRET to Extend DNA-Scaffolded Photonic Networks and Increase Light-Harvesting Capability (Advanced Optical Materials 1/2018)

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Advanced Optical Materials 2018年第1期6卷

作者： William P. Klein Sebastián A. Díaz Susan Buckhout-White Joseph S. Melinger Paul D. Cunningham Ellen R. Goldman Mario G. Ancona Wan Kuang Igor L. Medintz Center for Bio/Molecular Science and Engineering Code 6900 U.S. Naval Research Laboratory Washington DC 20375 USA Electronics Science and Technology Division Code 6800 U.S. Naval Research Laboratory Washington DC 20375 USA Department of Electrical and Computer Engineering Boise State University Boise ID 83706 USA

Experimental investigations on variable field flux control of a claw pole type half-wave rectified variable field flux motor

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Experimental investigations on variable field flux control o...

International Conference on electrical Machines and Systems (ICEMS)

作者： Yuta Nakashima Takashi Abe Tsuyoshi Higuchi Division of Electrical Engineering and Computer Science Nagasaki University Nagasaki Japan

ISBN: (纸本)9781467388634

Recently development of the new concept motor for EV/HEV becomes very active. Due to the demands of expanding the high efficiency and controllable torque area, we proposed a novel Claw Pole Type Half-Wave Rectified Variable Field Flux Motor (CP-HVFM). This motor is simple and robust brushless structure and has variable field flux performance. This paper introduces the principle of variable field flux excitation method. And we evaluate an influence of the variable field flux on the torque and efficiency characteristics.

关键词： Synchronous motors Brushless motors Rotors Traction motors Torque Windings AC motors

The evaluation of the positioning accuracy in the position control method using measured torque curves for switched reluctance motor

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The evaluation of the positioning accuracy in the position c...

International Conference on electrical Machines and Systems (ICEMS)

作者： Yuichi Okada Takashi Abe Tsuyoshi Higuchi Division of Electrical Engineering and Computer Science Nagasaki University Nagasaki Japan

ISBN: (纸本)9781467388634

This research aims to examine the possibility of Switched Reluctance Motor (SRM) for the application to servo system. Our previous paper proposed a position control method using measured torque curves for SRM and confirmed the usability for position control under the various load conditions. This paper confirms whether the actual position reaches the position command without overshoot and keeps stopping at position command. In consequence, the positioning accuracy in the proposed method is evaluated under the various load conditions.

关键词： Torque Position control Rotors Position measurement Torque measurement Switched reluctance motors

Testbeds for transition metal dichalcogenide photonics: Efficacy of light emission enhancement in monomer vs. Dimer nanoscale antennae

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arXiv 2017年

作者： Tahersima, Mohammad H. Birowosuto, M. Danang Ma, Zhizhen Sarpkaya, Ibrahim Coley, William C. Valentin, Michael D. Lu, I. Hsi Liu, Ke Zhou, Yao Martinez, Aimee Liao, Ingrid Davis, Brandon N. Martinez, Joseph Alvillar, Sahar Naghibi Martinez-Ta, Dominic Guan, Alison Nguyen, Ariana E. Soci, Cesare Reed, Evan Bartels, Ludwig Sorger, Volker J. Department of Electrical and Computer Engineering George Washington University 800 22nd Street NW WashingtonDC20052 United States Chemistry and Materials Science & Engineering University of California RiversideCA92521 United States Division of Physics and Applied Physics Nanyang Technological University 21 Nanyang Link Singapore637371 Singapore Department of Materials Science and Engineering Stanford University StanfordCA94305 United States

Monolayer transition metal dichalcogenides are uniquely-qualified materials for photonics because they combine well-defined tunable direct band gaps and self-passivated surfaces without dangling bonds. However, the atomic thickness of these two-dimensional (2D) materials results in low photo absorption limiting the achievable photo luminescence intensity. Such emission can, in principle, be enhanced via nanoscale antennae resulting in;a) an increased absorption cross-section enhancing pump efficiency, b) an acceleration of the internal emission rate via the Purcell factor mainly by reducing the antenna’s optical mode volume beyond the diffraction limit, and c) improved impedance matching of the emitter dipole to the free-space wavelength. Plasmonic dimer antennae show orders of magnitude hot-spot field enhancements when an emitter is positioned exactly at the mid-gap. However, a 2D material cannot be grown, or easily transferred, to reside in mid-gap of the metallic dimer cavity. In addition, a spacer layer between the cavity and the emissive material is required to avoid non-radiative recombination channels. Using both computational and experimental methods, in this work we show that the emission enhancement from a 2D emitter- monomer antenna cavity system rivals that of dimers at much reduced lithographic effort. We rationalize this finding by showing that the emission enhancement in dimer antennae does not specifically originate from the gap of the dimer cavity, but is an average effect originating from the effective cavity crosssection taken below each optical cavity where the emitting 2D film is located. In particular, we test an array of different dimer and monomer antenna geometries and observe a representative ~300% higher emission for both monomer and dimer cavities as compared to intrinsic emission of Chemical Vapor Deposition (CVD)-synthesized WS2 flakes. Observed enhanced light emission from these atomically thin flakes together with the lithographic con

关键词： Plasmonics

Search for resonances decaying into photon pairs in 139 fb-1of pp collisions at √s = 13 TeV with the ATLAS detector

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arXiv 2021年

作者： Aad, G. Abbott, B. Abbott, D.C. Abed Abud, A. Abeling, K. Abhayasinghe, D.K. Abidi, S.H. AbouZeid, O.S. Abraham, N.L. Abramowicz, H. Abreu, H. Abulaiti, Y. Acharya, B.S. Achkar, B. Adam, L. Adam Bourdarios, C. Adamczyk, L. Adamek, L. Adelman, J. Adiguzel, A. Adorni, S. Adye, T. Affolder, A.A. Afik, Y. Agapopoulou, C. Agaras, M.N. Aggarwal, A. Agheorghiesei, C. Aguilar-Saavedra, J.A. Ahmad, A. Ahmadov, F. Ahmed, W.S. Ai, X. Aielli, G. Akatsuka, S. Akbiyik, M. Åkesson, T.P.A. Akilli, E. Akimov, A.V. Al Khoury, K. Alberghi, G.L. Albert, J. Alconada Verzini, M.J. Alderweireldt, S. Aleksa, M. Aleksandrov, I.N. Alexa, C. Alexopoulos, T. Alfonsi, A. Alfonsi, F. Alhroob, M. Ali, B. Ali, S. Aliev, M. Alimonti, G. Allaire, C. Allbrooke, B.M.M. Allen, B.W. Allport, P.P. Aloisio, A. Alonso, F. Alpigiani, C. Alunno Camelia, E. Alvarez Estevez, M. Alviggi, M.G. Amaral Coutinho, Y. CPPM Aix-Marseille Université CNRS/IN2P3 Marseille France Homer L. Dodge Department of Physics and Astronomy University of Oklahoma NormanOK United States Department of Physics University of Massachusetts AmherstMA United States CERN Geneva Switzerland II. Physikalisches Institut Georg-August-Universität Göttingen Göttingen Germany Department of Physics Royal Holloway University of London Egham United Kingdom Department of Physics University of Toronto TorontoON Canada Niels Bohr Institute University of Copenhagen Copenhagen Denmark Department of Physics and Astronomy University of Sussex Brighton United Kingdom Raymond and Beverly Sackler School of Physics and Astronomy Tel Aviv University Tel Aviv Israel Department of Physics Technion Israel Institute of Technology Haifa Israel High Energy Physics Division Argonne National Laboratory ArgonneIL United States INFN Gruppo Collegato di Udine Sezione di Trieste Udine Italy ICTP Trieste Italy Department of Physics King's College London London United Kingdom Institut für Physik Universität Mainz Mainz Germany LAPP Univ. Savoie Mont Blanc CNRS/IN2P3 Annecy France AGH University of Science and Technology Faculty of Physics and Applied Computer Science Krakow Poland Department of Physics Northern Illinois University DeKalbIL United States Department of Physics Bogazici University Istanbul Turkey Istanbul University Dept. of Physics Istanbul Turkey Département de Physique Nucléaire et Corpusculaire Université de Genève Genève Switzerland Particle Physics Department Rutherford Appleton Laboratory Didcot United Kingdom Santa Cruz Institute for Particle Physics University of California Santa Cruz Santa CruzCA United States CLab Universite Paris-Saclay CNRS/IN2P3 Orsay91405 France LPC Université Clermont Auvergne CNRS/IN2P3 Clermont-Ferrand France Institute for Mathematics Astrophysics and Particle Physics Radboud University/Nikhef Nijmegen Netherlands Department of Physics Alexandru

Searches for new resonances in the diphoton final state, with spin 0 as predicted by theories with an extended Higgs sector and with spin 2 using a warped extra-dimension benchmark model, are presented using 139 fb-1of √s = 13 TeV pp collision data collected by the ATLAS experiment at the LHC. No significant deviation from the Standard Model is observed and upper limits are placed on the production cross-section times branching ratio to two photons as a function of the resonance mass. © 2021, CC BY.

关键词： Resonance