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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： M.N. Ullah S. J. Lee D. Innes A. Weisenberger S. Abbaszadeh C. Levin Radiology Stanford University Stanford California United States of America Thomas Jefferson National Accelerator Facility Newport News Virginia United States of America Electrical and Computer Engineering University of California Santa Cruz Santa Cruz California United States of America Electrical Engineering Bioengineering Physics and Molecular Imaging Program at Stanford (MIPS) Stanford University Stanford California United States of America

ISBN: (数字)9798350388152

ISBN: (纸本)9798350388169

Utilizing Positron Emission Tomography-Computed Tomography (PET-CT) for three-dimensional imaging of plant dynamic rhizosphere phenomena presents a promising avenue for quantitative analysis of soil structure challenges. Integrating such imaging technology into Earth System Models (ESMs) could enhance the precision of soil structure data. Here, we are reporting the evaluation of PhytoPET, a PET scanner developed at the Thomas Jefferson National Accelerator Facility, designed for studying rhizosphere dynamics. PhytoPET features adaptable PET detector configurations, including 5 cm x 5 cm Hamamatsu H8500 position-sensitive photomultiplier tubes (PMT) coupled to $48 \times 48$ LYSO:Ce scintillator arrays, with individual pixel dimensions of $1 \mathrm{~mm} \times 1 \mathrm{~mm} \times 10 \mathrm{~mm}$. To assess and optimize PhytoPET’s imaging performance, three data sets were acquired and reconstructed for mini-resolution phantom scans. These included scenarios without experimental sensitivity maps, with detector sensitivity map correction using experimental data, and with multi-angle scanning to mitigate limited-angle tomography artifacts present due to the relatively large gaps between detectors. The average peak-to-valley ratio (PVR) for selected line profile data with analytical sensitivity, experimental sensitivity, and experimental sensitivity correction plus multi-angle scanning were measured to be 1.90, 1.93, and 3.0, respectively. Reconstructed images from all scenarios are presented, showing that experimental sensitivity map correction combined with multi-angle scanning outperforms the other two approaches.

关键词： Temperature sensors Semiconductor device measurement Sensitivity Scintillators Statistical analysis Semiconductor detectors Positrons

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Optimizing Marker Design to Improve Precision of Optical Camera-Based Rigid-Body Motion Tracking and Correction in Medical Imaging

Optimizing Marker Design to Improve Precision of Optical Cam...

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2021 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2021

作者： Fisher, Jonathan Kim, Chris C. Groll, Andrew Levin, Craig S. Stanford University Department of Electrical Engineering CA United States Stanford University Department of Computer Science CA United States Stanford University Department of Radiology Molecular Imaging Program CA United States Bioengineering at Stanford University Department of Radiology and by Courtesy Physics Electrical Engineering CA United States

ISBN: (纸本)9781665421133

In this work we evaluated the performance of a camera-based rigid body motion correction solution using a 2D checkerboard marker and a 3D encoded marker. The context of the results presented is in PET/MR imaging, but in principle this motion compensation method could be used in any type of medical imaging modality. A high precision, computer-controlled motion stage with four degrees of freedom was used to control the marker positions and orientations (a.k.a. 'poses'). Still images of the markers taken in different poses mimicking a patient moving her/his head from side to side, were used to assess performance of this method. Comparing the known stage motion to the estimated motion, our results indicate that the 2D marker achieves better angular accuracy while the 3D marker's translational (linear) accuracy is superior. For all axes, the angular error was less than 0.96, 0.35 [deg], and the translational error was less than 2.24, 4.76 [mm] for the 3D and 2D markers, respectively. © 2021 IEEE.

关键词： Medical imaging

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Metallization of colloidal crystals

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Physical Review Materials 2021年第11期5卷 115601-115601页

作者： Ali Ehlen Hector Lopez-Rios Monica Olvera de la Cruz Applied Physics Program Northwestern University Evanston Illinois 60208 USA Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA Department of Physics and Astronomy Northwestern University Evanston Illinois 60208 USA

Colloidal crystals formed by size-asymmetric binary particles coassemble into a wide variety of colloidal compounds with lattices akin to ionic crystals. Recently, a transition from a compound phase with a sublattice of small particles to a metal-like phase in which the small particles are delocalized has been predicted computationally and observed experimentally. In this colloidal metallic phase, the small particles roam the crystal maintaining the integrity of the lattice of large particles, as electrons do in metals. A similar transition also occurs in superionic crystals, termed sublattice melting. Here, we use energetic principles and a generalized molecular dynamics model of a binary system of functionalized nanoparticles to analyze the transition to sublattice delocalization in different coassembled crystal phases as a function of temperature (T), number of grafted chains on the small particles, and number ratio between the small and large particles ns:nl. We find that ns:nl is the primary determinant of crystal type due to energetic interactions and interstitial site filling, while the number of grafted chains per small particle determines the stability of these crystals. We observe first-order sublattice delocalization transitions as T increases, in which the host lattice transforms from low- to high-symmetry crystal structures, including A20 → bct → bcc, Ad → bct → bcc, and bcc → bcc/fcc → fcc transitions and lattices. Analogous sublattice transitions driven primarily by lattice vibrations have been seen in some atomic materials exhibiting an insulator-metal transition also referred to as metallization. We also find minima in the lattice vibrations and diffusion coefficient of small particles as a function of ns:nl, indicating enhanced stability of certain crystal structures for ns:nl values that form compounds.

关键词： Crystal structure Diffusion Peierls transition Phase diagrams Phase transitions Self-assembly Colloidal crystal Molecular dynamics

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Revisiting the Assessment of Magnetic Texture of Magnets: The Role of Coercivity

SSRN

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SSRN 2024年

作者： Quispe, Luis T. Antunes, Leonardo F. Baldárrago-Alcántara, Apuniano A. Macedo, Wagner C. Rosa, Marcelo Augusto Rebelo, Querem H.F. Lopes, Leonardo U. Souza, Sérgio Michielon Wendhausen, Paulo Antônio Pereira Magnetic Materials Laboratory MAGMA Federal University of Santa Catarina Florianopolis88040-900 Brazil Graduate Program in Materials Science and Engineering PGMAT Federal University of Santa Catarina Florianopolis88040-900 Brazil Institute of Engineering and Geosciences Federal University of Western Pará Pará Santarém68035-110 Brazil Department of Materials Physics Federal University of Manaus Manaus69077-000 Brazil

A crucial figure of merit of magnets is their magnetic texture, because it is closely related to the maximum remanence a magnet can achieve, hence assessing the magnetic texture is pivotal in terms of magnet’s performance. Fernengel et al. (1996) developed a methodology based on magnetometry, which allows for a quick determination of the texture by calculating the degree of alignment 〈cosθ〉 from the remanent magnetization in directions parallel and perpendicular to the texture axis of the magnet. Although this method provided reliable values, its application was limited to magnets with high degrees of alignment (〈cosθ〉 > 95%), a restriction that was corrected by Quispe et al. (2020). Nevertheless, recent experiments have indicated that the magnetometry technique can introduce errors in texture assessment when the magnet presents high levels of coercivity. This work presents an approach that incorporates a correction factor into the magnetometry technique, accounting for the effect of the coercivity and circumventing this error source in texture assessment. The proposed methodology has been successfully applied to magnets with varying levels of coercivity. © 2024, The Authors. All rights reserved.

关键词： Coercive force

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Gapless symmetry-protected topological phase of quantum antiferromagnets on anisotropic triangular strip

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Physical Review B 2022年第14期106卷 144436-144436页

作者： Yuichiro Hidaka Shunsuke C. Furuya Atsushi Ueda Yasuhiro Tada Institute for Solid State Physics University of Tokyo Kashiwa 277-8581 Japan Department of Physics Ibaraki University Mito Ibaraki 310-8512 Japan Department of Basic Science University of Tokyo Meguro Tokyo 153-8902 Japan Quantum Matter Program Graduate School of Advanced Science and Engineering Hiroshima University Higashihiroshima Hiroshima 739-8530 Japan

We study a three-leg spin-1/2 ladder with geometrically frustrated interleg interactions. We call this model an anisotropic triangular-strip (ATS) model. We numerically and field-theoretically show that its ground state belongs to a gapless symmetry-protected topological (SPT) phase. The numerical approach is based on density-matrix renormalization group analyses of the entanglement entropy and the entanglement spectrum. Whereas the entanglement entropy exhibits a critical behavior, the entanglement spectrum is nontrivially degenerate. These entanglement properties imply that the ground state is a gapless topological phase. We investigate the ATS model using a quantum field theory to support the numerical findings. When the frustrated interchain interaction is deemed a perturbation acting on the three spin chains, the frustrated interchain interaction almost isolates the second chain from the other two chains. However, at the same time, the second chain mediates a ferromagnetic interaction between the first and third chains. Therefore, the ground state of the ATS model is a gapless Tomonaga-Luttinger liquid weakly coupled to a spin-1 Haldane chain with irrelevant interactions. Last but not least, we show that the gapless SPT phase of the ATS model is a symmetry-protected critical phase. We point out that the symmetry protection of criticality is essential in characterization of the gapless SPT phase.

关键词： Entanglement entropy Symmetry protected topological states Strongly correlated systems Bosonization Density matrix renormalization group Quantum spin chains

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Low-Loss, Nonvolatile Tuning of Bragg Structures with Sb2Se3

Low-Loss, Nonvolatile Tuning of Bragg Structures with Sb2Se3

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Conference on Lasers and Electro-Optics (CLEO)

作者： Nicholas A. Nobile Chuanyu Lian Hongyi Sun Yi-Siou Huang Brian Mills Cosmin Constantin Popescu Dennis Callahan Juejun Hu Carlos A. Ríos Ocampo Nathan Youngblood Electrical & Computer Engineering Department University of Pittsburgh Pittsburgh PA USA Department of Materials Science & Engineering University of Maryland College Park MD USA Institute for Research in Electronics and Applied Physics University of Maryland College Park MD USA Department of Materials Science & Engineering Massachusetts Institute of Technology Cambridge MA USA Draper Scholar Program The Charles Stark Draper Laboratory Inc Cambridge MA USA The Charles Stark Draper Laboratory Inc Cambridge MA USA

Sb 2 Se 3 is used to switch between broadband transparency and enhanced index contrast in two device types leveraging Bragg gratings for tunable stop-and pass-band functionalities. Experimental results highlight fabr... 详细信息

ISBN: (纸本)9798350369311

关键词： Bragg gratings Waveguide transitions Phase change materials Optical filters Optical switches Refractive index Fabry-Perot Indexes Passband Optical waveguides

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High fluorescent carbon dots/Ag as a sensitive sensor for tetracycline waste in aqueous solution 10

High fluorescent carbon dots/Ag as a sensitive sensor for te...

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10th International Seminar on New Paradigm and Innovation of Natural Sciences and itsApplication, ISNPINSA 2020

作者： Alkian, I. Sutanto, H. Hadiyanto, H. Hidayanto, E. Hapsari, H.P. Wibowo, A.A. Syahida, A.N. Irianti, F.D.D. Master Program of Environmental Science School of Postgraduate Studies Diponegoro University Semarang Indonesia Departemen of Physics Faculty of Science and Mathematics Diponegoro University Semarang Indonesia Departemen of Chemical Engineering Faculty of Engineering Diponegoro University Semarang Indonesia Smart Materials Research Center Laboratory Diponegoro University Semarang Indonesia

Currently, antibiotics waste produced by hospitals and pharmacies is increasing, increasing demand and public consumption. Tetracyclines are a popular type of antibiotic that can pollute the environment even in low concentrations. This study aimed to detect tetracyclines in an aqueous environment using C-dots/Ag. C-dots material was synthesized by microwave radiation method with the addition of Ag 0-4 %. C-dots/Ag is produced in the form of a brown-black powder that glows green. FTIR testing shows that C-dots/Ag contains various functional groups O-H, N-H, C-H, C=O, and C=C. The surface morphology of the C-dots based on SEM testing is round and rough. Ag's addition causes C-dots' surface morphology to agglomerate, shifting the C-dots' absorbance peaks towards a larger wavelength and decreasing the energy bandgap. C-dots/Ag 2% has the best optical properties based on the intensity of the resulting fluency. In general, C-dots/Ag has excellent potential to be a susceptible, selective, and effective tetracycline detection agent. © Published under licence by IOP Publishing Ltd.

关键词： Surface morphology

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Chiral anomaly and Weyl orbit in three-dimensional Dirac semimetal Cd3As2 grown on Si

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Nanotechnology 2024年第16期35卷 165002-165002页

作者： Lin, Wei-Chen Tsai, Peng-Ying Zou, Jia-Zhu Lee, Jie-Ying Kuo, Chun-Wei Lee, Hsin-Hsuan Pan, Ching-Yang Yang, Cheng-Hsueh Chen, Sheng-Zong Wang, Jyh-Shyang Jiang, Pei-Hsun Liang, Chi-Te Chuang, Chiashain Taiwan International Graduate Program Academia Sinica Taipei115 Taiwan Department of Engineering and System Science National Tsing Hua University Hsinchu300 Taiwan Graduate Institute of Applied Physics National Taiwan University Taipei106 Taiwan National Taiwan University Taipei106 Taiwan Department of Electronic Engineering Chung Yuan Christian University Taoyuan320 Taiwan Department of Physics Chung Yuan Christian University Taoyuan320 Taiwan Department of Physics National Taiwan Normal University 106 Taiwan Research Center for Semiconductor Materials and Advanced Optics Chung Yuan Christian University Taoyuan320 Taiwan

Preparing Cd3As2, which is a three-dimensional (3D) Dirac semimetal in certain crystal orientation, on Si is highly desirable as such a sample may well be fully compatible with existing Si CMOS technology. However, there is a dearth of such a study regarding Cd3As2 films grown on Si showing the chiral anomaly. Here, for the first time, we report the novel preparation and fabrication technique of a Cd3As2 (112) film on a Si (111) substrate with a ZnTe (111) buffer layer which explicitly shows the chiral anomaly with a nontrivial Berry’s phase of π. Despite the Hall carrier density ( n 3 D ≈ 9.42 × 10 17 cm−3) of our Cd3As2 film, which is almost beyond the limit for the portents of a 3D Dirac semimetal to emerge, we observe large linear magnetoresistance in a perpendicular magnetic field and negative magnetoresistance in a parallel magnetic field. These results clearly demonstrate the chiral magnetic effect and 3D Dirac semimetallic behavior in our silicon-based Cd3As2 film. Our tailoring growth of Cd3As2 on a conventional substrate such as Si keeps the sample quality, while also achieving a low carrier concentration. © 2024 IOP Publishing Ltd.

关键词： II-VI semiconductors

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Lattice Dynamics, Mechanical Properties, Electronic Structure and Magnetic Properties of Equiatomic Quaternary Heusler Al-loys CrTiCoZ (Z =Al,Si) using first principles calculations

arXiv

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arXiv 2022年

作者： Andharia, Eesha Alquarashi, Hind Hamad, Bothina Department of Physics University of Arkansas FayettevilleAR72701 United States Materials Science and Engineering Program University of Arkansas FayettevilleAR72701 United States Physics Department at the College of Science Al Baha University Al Bahah65527 Saudi Arabia Physics Department The University of Jordan Amman11942 Jordan

First principles calculations are performed to investigate the thermodynamical stabil-ity, dynamical, mechanical, electronic and magnetic properties of CrTiCoZ (Z= Al/Si) novel quater-nary Heusler alloys. Y-type III atomic configuration is found to be the most stable structure for both compounds. The lattice constant values obtained using GGA-PBE approach are 5.9368Å and 5.7853Å for CrTiCoAl and CrTiCoSi, respectively. Using the value of elastic moduli for both the compounds, the computed Pugh's ratio value is 2.5 and 2.7 for CrTiCoAl and CrTiCoSi, respectively, which is higher than 1.75, indicating both the compounds are ductile in nature. The melting tem-peratures of both compounds are as high as 2142K and 2420K for CrTiCoAl and CrTiCoSi, respec-tively. The electronic structure calculations using GGA-PBE approach show a half metallic behavior of CrTiCoAl. The spin-down channel exhibits a direct band gap of 0.15 eV, whereas the spin-up channel is metallic making CrTiCoAl a half metallic ferromagnet with 100% spin polarization and an appreciable magnetic moment of-2μB. However, CrTiCoSi is found to be semi-metallic in the spin-down channel and metallic in the spin-up channel, which leads to a spin polarization of 99.7% with a non-integer magnetic moment of-0.99μB. The Curie temperature of CrTiCoAl is well above the room temperature (385K), whereas that of CrTiCoSi is below the room temperature (203K). Thus, CrTiCoAl is found to be more promising than CrTiCoSi as a spin injector in spintronic devices. © 2022, CC BY.

关键词： Density functional theory

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Drone-borne calibration pulser for radio observatories detecting ultra-high-energy cosmic rays and neutrinos 38

Drone-borne calibration pulser for radio observatories detec...

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38th International Cosmic Ray Conference, ICRC 2023

作者： Nam, J. Kuo, C.-Y. Shin, B.K. Chen, P. Chen, Y. Hsu, S.-Y. Huang, J.-J. Huang, M.-H.A. Leung, C.H. Liu, T.-C. Wang, S.-H. Wang, M.-Z. Wang, Y.-H. Besson, D. Novikov, A. Hornhuber, C. Young, R. Department of Physics National Taiwan University Taipei Taiwan Leung Center for Cosmology and Particle Astrophysics National Taiwan University Taipei Taiwan Ulsan National Institute of Science and Technology Ulsan Korea Republic of Department of Energy and Resources National United University Miaoli Taiwan Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu300 Taiwan Department of applied physics National PingTung university PingTung900 Taiwan Chung Cheng Institute of Technology National Defense University TaoYuan335 Taiwan Undergraduate Degree Program of Systems Engineering and Technology National Yang Ming Chiao Tung University Hsinchu300 Taiwan Department of Physics and Astronomy University of Kansas Lawrence United States Instrumentation Design Lab University of Kansas Lawrence United States Moscow Russia Institute of Astronomy and Astrophysics Academia Sinica Astronomy-Mathematics Building No. 1 Sec. 4 Roosevelt Rd. Taipei Taiwan

We report on the development of a drone-borne calibration pulser (cal-pulser) for radio observatories detecting ultra-high energy (UHE) cosmic rays and neutrinos. This system allows us to calibrate the radio detector in its field of view regardless of the accessibility of the site. The system is compact and sufficiently lightweight to be attached to a commercial drone. It consists of a solid-state high-power pulse generator, a programmable attenuator, a transmitting antenna, and a differential GPS (D-GPS) module. The drone, with the ∼1.3 kg payload, has a typical flight time of around 25 minutes, corresponding to a maximum flight distance of around 10 km. After developing the first version of the system in 2019, it successfully demonstrated its calibration performance with the TAROGE stations in Taiwan and the TAROGE-M station in Mt. Melbourne, Antarctica. In 2022, the system was upgraded with a dual-band D-GPS for more reliable operation and more accurate determination of the coordinates of the cal-pulser. In addition to the cal-pulser, we investigated aerial photogrammetry using the built-in camera and the D-GPS, which is an efficient method to determine the coordinates of the detector. For objects within 10 m of the drone, an accuracy of a few millimeter was achieved. These drone-borne cal-pulser and the photogrammetry have become essential calibration procedures in the TAROGE-M experiment. We suggest these approaches may find application in many other radio experiments that detect UHE cosmic rays and neutrinos, such as ARIANNA, BEACON, GRAND, as well as IceCube-Gen2. © Copyright owned by the author(s) under the terms of the Creative Commons.

关键词： Cosmic rays

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