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arXiv 2023年

作者： Millsaps, William Schwartz, Jonathan Di, Zichao Wendy Jiang, Yi Hovden, Robert Department of Nuclear Engineering & Radiological Sciences University of Michigan Ann ArborMI United States Department of Materials Science and Engineering University of Michigan Ann ArborMI United States Mathematics and Computer Science Division Argonne National Laboratory LemontIL United States Advanced Photon Source Facility Argonne National Laboratory LemontIL United States Applied Physics Program University of Michigan Ann ArborMI United States

This manuscript is published in Microscopy and Microanalysis (DOI: 10.1093/micmic/ozad083). Modern electron tomography has progressed to higher resolution at lower doses by leveraging compressed sensing methods that minimize total variation (TV). However, these sparsity-emphasized reconstruction algorithms introduce tunable parameters that greatly influence the reconstruction quality. Here, Pareto front analysis shows that high-quality tomograms are reproducibly achieved when TV minimization is heavily weighted. However, in excess, compressed sensing tomography creates overly smoothed 3D reconstructions. Adding momentum to the gradient descent during reconstruction reduces the risk of over-smoothing and better ensures that compressed sensing is well behaved. For simulated data, the tedious process of tomography parameter selection is efficiently solved using Bayesian optimization with Gaussian processes. In combination, Bayesian optimization with momentum-based compressed sensing greatly reduces the required compute time-an 80% reduction was observed for the 3D reconstruction of SrTiO3 nanocubes. Automated parameter selection is necessary for large scale tomographic simulations that enable the 3D characterization of a wider range of inorganic and biological materials. © 2023, CC BY.

关键词： Compressed sensing

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Development of a Pixelated BaF2 Test Bed for Timing Applications

Development of a Pixelated BaF2 Test Bed for Timing Applicat...

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IEEE Symposium on nuclear Science (NSS/MIC)

作者： Tyler A. Jordan Madison T. Andrews Christopher R. Johnson Edward A. McKigney Sy Stange Kai Vetter Department of Nuclear Engineering University of California Berkeley CA USA Radiation Transport Applications Group (XCP-7) Los Alamos National Laboratory Los Alamos NM USA Advanced Nuclear Technology Group (NEN-2) Los Alamos National Laboratory Los Alamos NM USA Applied Nuclear Physics Program Lawrence Berkeley National Laboratory Berkeley CA USA

Prototype pixelated BaF 2 detectors for timing applications have been assembled using state-of-the-art commercial off-the-shelf components. 64 square rods of pure BaF 2 (4.6 mm × 4.6 mm × 30 mm) are air-coupled in an 8 × 8 array to a Photonis XP85112 Planacon multianode microchannel plate photomultiplier tube; shortpass optical transmission interference filters may be inserted between the crystal array and photodetector to suppress the slow, self-trapped exciton luminescence. Three filter variants with different long wavelength cutoffs were tested experimentally, and the performance of each filter is assessed. The results of these and upcoming detector characterization exeriments will ascertain how well new technologies can leverage the unique timing properties of BaF 2 in a practical system, and provide quantitative guidance for effective continued development.

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Particle size effect of La2CuO4 nanoparticles

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Interactions 2024年第1期245卷 212-212页

作者： Putri, Anita Eka Kurniawan, Budhy Sari, Dita Puspita Syakuur, Muhammad Abdan Watanabe, Isao Meson Science Laboratory RIKEN Nishina Center 2-1 Hirosawa Saitama Wako351-0198 Japan Physics Departement Universitas Indonesia West Java Depok16424 Indonesia Innovative Global Program College of Engineering Shibaura Institute of Technology Saitama Omiya337-8570 Japan Department of Chemistry Padjadjaran University Sumedang Jatinangor45363 Indonesia Nuclear Structure Research Group RIKEN Nishina Center 2-1 Hirosawa Saitama Wako351-0198 Japan

A particle size effect to magnetic properties of the mother material of the La-based high-Tc superconducting oxides, La2CuO4 (LCO), was investigated using muon spin relaxation (μSR) measurement in the zero-field condition. A decrease in the Nèel temperature was observed in LCO nanoparticles with a decreasing particle size. The magnetic ground state was found to be an antiferromagnetically ordered state as observed in the bulk state. Two muon sites were confirmed, which showed different temperature dependence of internal fields. It is guessed that oxygen molecules are trapped among nanoparticles, forming a domain-like structure [1]. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.

关键词： Nanoparticles

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Antibacterial evaluation of radiolytically synthesized silver nanoparticles with ι-carrageenan stabilizers

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Radiation physics and Chemistry 2025年 236卷

作者： Gili, Mon Bryan Z. Manuel, Wendell A. Guillermo, Neil Raymund D. Shankaregowda, Rakshith Gowda H. Phan, Manh-Huong Conato, Marlon T. Vega, Marienette M. Department of Science and Technology Philippine Nuclear Research Institute Commonwealth Avenue Diliman Quezon City1101 Philippines Materials Science and Engineering Program College of Science University of the Philippines Diliman Diliman Quezon City1101 Philippines Department of Physics University of South Florida 4202 East Fowler Avenue TampaFL33620 United States Institute of Chemistry College of Science University of the Philippines Diliman Diliman Quezon City1101 Philippines

The synthesis of silver nanoparticles (AgNPs) using green, eco-friendly methods has garnered significant attention due to the potential advantages of using natural polymers, such as ι-carrageenan, as stabilizing agents. However, challenges remain in controlling the size, distribution, and stability of the nanoparticles, as well as optimizing their antimicrobial activity. In this study, gamma irradiation of ι-carrageenan solutions was investigated as a method for synthesizing AgNPs and exploring their antimicrobial properties. The primary objective was to assess how varying radiation doses and ι-carrageenan concentrations affect the formation, size distribution, and antimicrobial activity of the AgNPs. ι-Carrageenan solutions (0.1, 0.5, and 1.0 w/v %) were mixed with 0.2 M silver nitrate (AgNO3) solutions and irradiated at doses ranging from 0 to 20 kGy using Co-60. UV–vis spectroscopic analysis indicated the successful formation of AgNPs, with surface plasmon resonance (SPR) peaks appearing between 402 and 418 nm. These peaks shifted slightly towards shorter wavelengths as the irradiation rose, signaling a reduction in nanoparticle size. The optimal synthesis of AgNPs occurred at 0.5 % ι-carrageenan concentration and a dose of 15 kGy, where the SPR peak intensity and nanoparticle formation were most pronounced. XRD confirmed the presence of silver nanoparticles with face-centered cubic (FCC) structure. Particle size analysis, using dynamic light scattering (DLS), revealed that AgNPs ranged in size from 85 to 142 nm, with smaller particles forming at higher doses. At a 1 kGy dose, the nanoparticle size averaged 114 nm, but increased doses (15–20 kGy) led to a significant reduction in particle size to 85 nm. This size reduction was attributed to the fragmentation of larger particles as the irradiation dose increased. Fourier-transform infrared (FTIR) spectroscopy showed notable changes in the ι-carrageenan structure, with the formation of new functional groups, includ

关键词： Fourier transform infrared spectroscopy

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Collective excitations in the tetravalent lanthanide honeycomb antiferromagnet Na2PrO3

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Physical Review B 2021年第12期103卷 L121109-L121109页

作者： M. J. Daum A. Ramanathan A. I. Kolesnikov S. Calder M. Mourigal H. S. La Pierre School of Physics Georgia Institute of Technology Atlanta Georgia 30332 USA School of Chemistry and Biochemistry Georgia Institute of Technology Atlanta Georgia 30332 USA Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Nuclear and Radiological Engineering and Medical Physics Program School of Mechanical Engineering Georgia Institute of Technology Atlanta Georgia 30332 USA

Thermomagnetic and inelastic neutron-scattering measurements on Na2PrO3 are reported. This material is an antiferromagnetic honeycomb magnet based on the tetravalent lanthanide Pr4+ and has been proposed to host dominant antiferromagnetic Kitaev interactions. These measurements reveal magnetic fluctuations in Na2PrO3 below an energy of 2 meV as well as crystal-field excitations around 230 meV. The latter energy is comparable to the scale of the spin-orbit interaction and explains both the very small effective moment of around 1.0μB per Pr4+ and the difficulty to uncover any static magnetic scattering below the ordering transition at TN= 4.6 K. By comparing the low-energy magnetic excitations in Na2PrO3 to those of the isostructural spin-only compound, Na2TbO3, a microscopic model of exchange interactions is developed that implicates dominant and surprisingly large Heisenberg exchange interactions J≈1.1(1) meV. Although antiferromagnetic Kitaev interactions with K≤0.2J cannot be excluded, the inelastic neutron-scattering data of Na2PrO3 is best explained with a Δ=1.22 easy-axis XXZ exchange anisotropy.

关键词： Spin dynamics Lanthanides Crystal-field theory Kitaev-Heisenberg model

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Extension and verification of multi-group JFNK-generated uniform discontinuity factors for nodal diffusion applications

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Annals of nuclear Energy 2025年 223卷

作者： Jacob D. Smith Bailey Painter Emil Fridman Dan Kotlyar Nuclear and Radiological Engineering and Medical Physics Program George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta GA 30332-0405 USA Helmholtz-Zentrum Dresden-Rossendorf Bautzner Landstraße 400 01328 Dresden Germany

Monte Carlo (MC) neutron transport codes (e.g., MCNP, Serpent) yield high-fidelity spatial flux distributions, but are relatively resource intensive – to the point of being prohibitive – for advanced neutronics analyses (e.g., multiphysics coupling, transient simulations). MC codes can also generate few-group homogenized constants for use in reduced-order homogenous flux solvers, such as nodal diffusion codes. Discontinuity factors (DFs) are commonly applied to ensure that these codes reproduce the eigenvalue, node-average fluxes, and net surface currents obtained by a MC solver. A closely related approach is to use the Jacobian-free Newton Krylov (JFNK) method to generate a set of uniform discontinuity factors (JFNK-UDFs). The primary objective of this work is to compare the Flux Discontinuity Ratios (FDRs) associated with JFNK-UDFs against FDRs associated with reference DFs (RDFs), calculated via the nodal expansion method (NEM). Multiple verification cases, ranging from a 1D multi-nodal problem to a 2D small modular reactor (SMR) core, are used to compare the FDRs and the corresponding flux solutions. The homogenous solutions obtained by the nodal diffusion code, DYN3D, yield near perfect agreement with the reference power profiles only when complemented by the generated RDFs or the JFNK-UDFs.

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Dynamic Time-Over-Threshold Readout for Improved Energy Linearity in PET Detectors that Achieve 100 ps CTR

Dynamic Time-Over-Threshold Readout for Improved Energy Line...

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IEEE Symposium on nuclear Science (NSS/MIC)

作者： Shirin Pourashraf Andrea Gonzalez-Montoro Joshua W. Cates Zhixiang Zhao Jun Yeon Won Jae Sung Lee Craig S. Levin Department of Radiology Stanford University Stanford USA Applied Nuclear Physics Program at Lawrence Berkeley National Laboratory Berkeley USA School of Biomedical Engineering Shanghai Jiao Tong University Shanghai People's Republic of China Department of Nuclear Medicine and Biomedical Sciences Seoul National University Seoul South Korea Departments of Radiology Bioengineering Physics and Electrical Engineering Molecular Imaging Program Stanford University Stanford CA 94305

ISBN: (数字)9781665421133

ISBN: (纸本)9781665421140

We have embedded a dynamic time-over-threshold (DynTOT) block in our scalable TOF-PET detector readout electronics to linearize the multiplexed energy spectra while keeping 100 ps FWHM Coincidence Time Resolution (CTR) performance. This DynTOT block is constructed by off-the-shelve components and consumes only 20 mW power per detector ‘layer’ in our design. Using 3×3×10 mm³ "LGSO" crystals coupled to arrays of 3×3 mm² SiPMs, energy resolution of 13.8±0.1%, 13.9±0.3%, and 17.1±0.6% were experimentally achieved for conventional pulse height, DynTOT, and conventional TOT methods, respectively. Including the DynTOT method, coincidence data were experimentally acquired using a low jitter FPGA-based TDC, and 103.6 ± 1.1 ps FWHM CTR was achieved, demonstrating the robustness of our novel and scalable timing electronic chain.

关键词： Multiplexing Energy resolution Linearity Detectors Crystals Jitter Robustness

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Simulations of the Collisional Bohm Criterion and Edge-to-Center Density Ratio Over a Range of Gas Pressure

Simulations of the Collisional Bohm Criterion and Edge-to-Ce...

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IEEE International Conference on Plasma Science (ICOPS)

作者： L. P. Beving M. Hopkins S. D. Baalrud University of Michigan Applied Physics Program Ann Arbor Michigan United States of America Applied Optical and Plasma Sciences Sandia National Laboratories Albuquerque New Mexico United States of America Department of Nuclear Engineering and Radiological Sciences University of Michigan Ann Arbor Michigan United States of America

ISBN: (纸本)9781665479264

The flux of plasma into the sheath is the product of the ion velocity and density at the sheath edge Γ=n se V se . When ionneutral collisions are rare Bohm's criterion relates the sheath edge flux to bulk parameters Γ=h l n 0 c s , where h l is the edge-tocenter density ratio and c s is the sound speed. However, when the gas pressure increases and the ion-neutral mean free path approaches the electron Debye length the ions are not expected to reach c s , but instead a collisional Bohm criterion a l c s where 0

关键词： Conferences Predictive models Ions Plasmas

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Design Considerations for 3D Position Sensitive Scintillation Detectors that Achieve 100 ps Coincidence Time Resolution

Design Considerations for 3D Position Sensitive Scintillatio...

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IEEE Symposium on nuclear Science (NSS/MIC)

作者： Shirin Pourashraf Zhixiang Zhao Andrea Gonzalez - Montoro Joshua W. Cates Jun Yeon Won Jae Sung Lee Craig S. Levin Department of Radiology Stanford University Stanford CA USA School of Biomedical Engineering Shanghai Jiao Tong University Shanghai People’s Republic of China Applied Nuclear Physics Program Lawrence Berkeley National Laboratory Berkeley CA USA Department of Nuclear Medicine and Biomedical Sciences Seoul National University Seoul South Korea Departments of Radiology Bioengineering Physics and Electrical Engineering Molecular Imaging Program Stanford University Stanford CA USA

ISBN: (数字)9781665421133

ISBN: (纸本)9781665421140

We have studied design considerations for three dimension positioning sensitive (3DPS) scalable TOF- PET detectors that achieve 100 ps coincidence time resolution (CTR). These scintillation detectors are based on 3×3×10 mm³ “LGSO” crystals side- coupled to arrays of 3×3 mm 2 SiPMs. A CPLD is used to provide 3 mm positioning resolution along the length of each crystal element. Revised mixed-signal front-end electronics decreased the power dissipation by 200% and increased the detector packing fraction while preserving the CTR performance. A low timing jitter FPGA-based TDC was used for data acquisition of the timing channels. Measured CTR was 102.2 ± 1.3 ps FWHM using a 22Na point source.

关键词： Timing jitter Three-dimensional displays Image resolution Data acquisition Detectors Crystals Timing

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Analyzes the effect of temperature on characteristics of crude oil permittivity sensor based on Interdigital Capacitors (IDCs)

Analyzes the effect of temperature on characteristics of cru...

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2019 International Conference on Science Education and Technology, ICOSETH 2019

作者： Rachmanita, R.E. Rudiyanto, B. Ahmadi, H. Seetawan, T. Renewable Energy Engineering Politeknik Negeri Jember Jember 164 Indonesia Polytechnic Institute of Nuclear Technology National Nuclear Energy Agency of Indonesia [BATAN Indonesia Center of Excellence on Alternative Energy Research and Development Institute and Program of Physics Sakon Nakhon Rajabat University Sakon Nakhon47000 Thailand

This study aims to analyze the effect of temperature on characteristics of crude oil permittivity sensor based on interdigital capacitors (IDCs), including linearity, repeatability and hysteresis. IDCs have been fabricated using the DC Magnetron Sputtering method in three designs with different electrode materials and the same electrode configuration. The electrode materials used silver (Ag), copper (Cu) and molybdenum (Mo) deposited on a FR-4 PCB substrate with a thickness of 1μm. The electrode configuration each design is 15 mm electrode length, 0.5 mm electrode width, 0.5 mm electrode distance and 40 electrodes number. The crude oil was tested at a temperature range of 30-70°C. The measurement system uses a PM6303A automatic RCL Meter at a frequency of 1 kHz. The sensor linearity test results showed an increase in the sensitivity value of the IDCs Ag, Mo and Cu sensors when the temperature was more than 50°C. The repeatability sensor test results showed that IDCs made from Ag had the highest measurement precision with a value of %repeatability is 2.5%. The hysteresis test results showed that the design IDCs made from Ag have high stability at high and low temperatures. © Published under licence by IOP Publishing Ltd.

关键词： Crude oil

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