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1,197 results on '"Kondo J"'

1. Multiphoton dressed Rydberg excitations in a microwave cavity with ultracold Rb atoms

Author

Kondo, J. D. Massayuki, Rittenhouse, Seth T., Magalhaes, Daniel Varela, Rokaj, Vasil, Mistakidis, S. I., Sadeghpour, H. R., and Marcassa, Luis Gustavo

Subjects
Physics - Atomic Physics
Abstract

We investigate magneto-optical trap loss spectroscopy of Rydberg excited $^{85}$Rb ($66\leq n \leq 68~S_{1/2}$) atoms, placed inside a tailored microwave cavity. The cavity frequency at 13.053 GHz is in resonance with the $67S_{1/2} \rightarrow 66P_{3/2}$ transition, inducing a ladder multiphoton microwave Rydberg absorption and emission. The observed spectra are modeled with an extended Jaynes-Cumming formalism that accounts for multiphoton absorption from and emission into the cavity, the loss from the trap due to Rydberg excitation, and cavity imperfection. We calculate the average photons in each spectral feature and find evidence for fractional photon emission into the cavity modes. The microwave cavity Rydberg spectroscopy in this work should inform the application and technology development of Rydberg based sensors and hybrid Rydberg atom-superconducting resonator quantum gates.

Published
2024

2. Resonance of Vector Vortex Beams in a Triangular Optical Cavity

Author

Rodrigues, L. M., Fagundes, L. Marques, Salles, D. C., Santos, G. H. dos, Kondo, J. M., Khoury, A. Z., Ribeiro, P. H. Souto, and de Araújo, R. Medeiros

Subjects
Physics - Optics, Physics - Applied Physics
Abstract

We experimentally demonstrate resonance of first-order vector vortex beams (VVB) with a triangular optical cavity. We also show that, due to their symmetry properties, the so-called radial and azimuthal VVBs do not resonate at the same cavity length, which could be explored to use the triangular resonator as a mode sorter. In addition, an intracavity Pancharatnam phase shifter (PPS) is implemented in order to compensate for any birefringent phase that the cavity mirrors may introduce.

Published
2023

3. Microdosimetric Analysis for Boron Neutron Capture Therapy via Monte Carlo Track Structure Simulation with Modified Lithium Cross-sections.

Author

Han, Yang, Geng, Changran, D-Kondo, J, Li, Mingzhu, Ramos-Méndez, José, Altieri, Saverio, Liu, Yuanhao, and Tang, Xiaobin

Subjects
Boron neutron capture therapy, Lineal energy, Microdosimetry, Monte Carlo track structure simulation
Abstract

Boron neutron capture therapy (BNCT) is a cellular-level hadron therapy achieving therapeutic effects via the synergistic action of multiple particles, including Lithium, alpha, proton, and photon. However, evaluating the relative biological effectiveness (RBE) in BNCT remains challenging. In this research, we performed a microdosimetric calculation for BNCT using the Monte Carlo track structure (MCTS) simulation toolkit, TOPAS-nBio. This paper reports the first attempt to derive the ionization cross-sections of low-energy (>0.025 MeV/u) Lithium for MCTS simulation based on the effective charge cross-section scalation method and phenomenological double-parameter modification. The fitting parameters λ1=1.101,λ2=3.486 were determined to reproduce the range and stopping power data from the ICRU report 73. Besides, the lineal energy spectra of charged particles in BNCT were calculated, and the influence of sensitive volume (SV) size was discussed. Condensed history simulation obtained similar results with MCTS when using Micron-SV while overestimating the lineal energy when using Nano-SV. Furthermore, we found that the microscopic boron distribution can significantly affect the lineal energy for Lithium, while the effect for alpha is minimal. Similar results to the published data by PHITS simulation were observed for the compound particles and monoenergetic protons when using micron-SV. Spectra with nano-SV reflected that the different track densities and absorbed doses in the nucleus together result in the dramatic difference in the macroscopic biological response of BPA and BSH. This work and the developed methodology could impact the research fields in BNCT where understanding radiation effects is crucial, such as the treatment planning system, source evaluation, and new boron drug development.

Published
2023

5. Low-drift Zeeman shifted atomic frequency reference

Author

Reed, D. J., Šibalić, N., Whiting, D. J., Kondo, J. M., Adams, C. S., and Weatherill, K. J.

Subjects
Physics - Atomic Physics
Abstract

We present a simple method for producing a low-drift atomic frequency reference based upon the Zeeman effect. Our Zeeman Shifted Atomic Reference `ZSAR' is demonstrated to have tens of GHz tuning range, limited only by the strength of the applied field. ZSAR uses Doppler-free laser spectroscopy in a thermal vapor where the vapor is situated in a large, static and controllable magnetic field. We use a heated $^{85}$Rb vapor cell between a pair of position-adjustable permanent magnets capable of applying magnetic fields up to 1 T. To demonstrate the frequency reference we use a spectral feature from the Zeeman shifted D1 line in $^{85}$Rb at 795 nm to stabilize a laser to the 7S$_{1/2}$ $\longrightarrow$ 23P$_{1/2}$ transition in atomic cesium, which is detuned by approximately 19 GHz from the unperturbed Rb transition. We place an upper bound on the stability of the technique by measuring a 2.5 MHz RMS frequency difference between the two spectral features over a 24 hour period. This versatile method could be adapted easily for use with other atomic species and the tuning range readily increased by applying larger magnetic fields., Comment: 8 pages, 4 figures

Published
2018
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7. Evaluation of Electrochemical Sensor Using Microfluidic System.

Author

Legassey, A., Fleming, A., Dagostino, L., Bliznakov, T., Gudlavalleti, R., Kondo, J., Papadimitrakopoulos, F., and Jain, F.

Subjects
FLOW sensors, ELECTROCHEMICAL sensors, PLATINUM electrodes, LASER beam cutting, BUFFER solutions, GLUCOSE oxidase
Abstract

This paper presents the characterization and testing of electrochemical sensor using microfluidic system. Various geometric patterns were laser cut into the platinum working electrode of a biosensor. In this work, a microfluidic chamber was designed that allows phosphate buffer solution (PBS) to flow across the sensor, using a peristaltic pump, while varying the concentration of hydrogen peroxide. The amperometric characterization of the electrochemical sensor with 25, 50, 75, and 100 μ m perforation and 75 μ m spacing showed the highest sensitivity. This result was to be expected the purpose of patterning the sensors was to provide a 3-dimensional structure to the planar electrode in order for the enzyme, glucose oxidase, to be immobilized. Future work will include selecting one of the patterns for immobilization of glucose oxidase allowing us to realize a fully functional glucose sensor. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Ionization detail parameters and cluster dose: a mathematical model for selection of nanodosimetric quantities for use in treatment planning in charged particle radiotherapy

Author

Faddegon, Bruce A, primary, Blakely, Eleanor A, additional, Burigo, Lucas Norberto, additional, Censor, Yair, additional, Dokic, Ivana, additional, D-Kondo, J Naoki, additional, Ortiz, Ramon, additional, Ramos-Mendez, Jose, additional, Rucinski, Antoni, additional, Schubert, Keith E, additional, Wahl, Niklas, additional, and Schulte, Reinhard W, additional

Published
2023
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37. A terahertz-driven non-equilibrium phase transition in a room temperature atomic vapour

Author

Wade, C. G., Marcuzzi, M., Levi, E., Kondo, J. M., Lesanovsky, I., Adams, C. S., and Weatherill, K. J.

Subjects
Science, Physics::Optics, lcsh:Q, Physics::Atomic Physics, lcsh:Science, Article
Abstract

There are few demonstrated examples of phase transitions that may be driven directly by terahertz frequency electric fields, and those that are known require field strengths exceeding 1 MV cm−1. Here we report a non-equilibrium phase transition driven by a weak (≪1 V cm−1), continuous-wave terahertz electric field. The system consists of room temperature caesium vapour under continuous optical excitation to a high-lying Rydberg state, which is resonantly coupled to a nearby level by the terahertz electric field. We use a simple model to understand the underlying physical behaviour, and we demonstrate two protocols to exploit the phase transition as a narrowband terahertz detector: the first with a fast (20 μs) non-linear response to nano-Watts of incident radiation, and the second with a linearised response and effective noise equivalent power ≤1 pW Hz−1/2. The work opens the door to a class of terahertz devices controlled with low-field intensities and operating in a room temperature environment., The nonlinear interaction between terahertz frequency electric fields and atoms or molecules can be used to study fundamental and technical problems. Here the authors demonstrate a THz–driven phase transition, with a potential application as a THz sensor, using Rydberg atomic states in a cesium vapor.

Published
2018

38. PsbP-induced protein conformational changes around Cl^− ions in the water oxidizing center of photosystem II

Author

Kondo, J. and Noguchi, T.

Subjects
oxygen evolution, photosynthesis, food and beverages, Mn4CaO5 cluster
Abstract

PsbP is an extrinsic protein of PSII having a function of Ca^2+ and Cl^− retention in the water-oxidizing center (WOC). In order to understand the mechanism how PsbP regulates the Cl^− binding in WOC, we examined the effect of PsbP depletion on the protein structures around the Cl^− sites using Fourier transform infrared (FTIR) spectroscopy. Light-induced FTIR difference spectra upon the S^1→S2 transition were obtained using Cl^−-bound and NO3^−-substituted PSII membranes in the presence and absence of PsbP. A clear difference in the amide I band changes by PsbP depletion was observed between Cl^−-bound and NO3^−-substituted PSII samples, indicating that PsbP binding perturbed the protein conformations around the Cl^−ion(s) in WOC. It is suggested that PsbP stabilizes the Cl^− binding by regulating the dissociation constant of Cl^− and/or an energy barrier of Cl^− dissociation through protein conformational changes around the Cl^− ion(s)., ファイル公開：2019/03/01

Published
2018

43. Ta3N5 and TaON thin films on Ta foil: surface composition and stability

Author

Hara, Michkazu, Chiba, Eisuke, Ishikawa, Akio, Takata, Tsuyoshi, and Kondo,J unko N.; Domen, Kazunari

Subjects
X-ray spectroscopy -- Usage, X-ray spectroscopy -- Reports, Dielectric films -- Research, Dielectric films -- Chemical properties, Thin films -- Research, Thin films -- Chemical properties, Photochemical research, Chemicals, plastics and rubber industries
Abstract

Thin films of Ta3N5 and TaON prepared on Ta foils are investigated in terms of surface composition and stability in air and in water to evaluate the effectiveness of these materials as visible light-responsiveness photocatalysts for water oxidation and reduction. X-ray photoelectron spectroscopy reveals that the surface of the TaN3 thin film becomes partially hydrolyzed in water.

Published
2003

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