Proof-of-principle experiment for testing strong-field quantum electrodynamics with exotic atoms; High precision X-ray spectroscopy of muonic neon

Okumura, Takuma*; Hashimoto, Tadashi; 40 of others*

Physical Review Letters, 130(17), p.173001_1 - 173001_7, 2023/04

https://doi.org/10.1103/PhysRevLett.130.173001

Dynamical response of transition-edge sensor microcalorimeters to a pulsed charged-particle beam

Okumura, Takuma*; Azuma, Toshiyuki*; Bennet, D. A.*; Caradonna, P.*; Chiu, I.-H.*; Doriese, W. B.*; Durkin, M. S.*; Fowler, J. W.*; Gard, J. D.*; Hashimoto, Tadashi; et al.

IEEE Transactions on Applied Superconductivity, 31(5), p.2101704_1 - 2101704_4, 2021/08

https://doi.org/10.1109/TASC.2021.3067793

A superconducting transition-edge sensor (TES) microcalorimeter is an ideal X-ray detector for experiments at accelerator facilities because of good energy resolution and high efficiency. To study the performance of the TES detector with a high-intensity pulsed charged-particle beam, we measured X-ray spectra with a pulsed muon beam at the Japan Proton Accelerator Research Complex (J-PARC) in Japan. We found substantial temporal shifts of the X-ray energy correlated with the arrival time of the pulsed muon beam, which was reasonably explained by pulse pileup due to the incidence of energetic particles from the initial pulsed beam.

High-performance quantum simulation for coupled Josephson junctions on the earth simulator; A Challenge to the Schrdinger equation on grids

Imamura, Toshiyuki*; Kano, Takuma*; Yamada, Susumu; Okumura, Masahiko*; Machida, Masahiko

International Journal of High Performance Computing Applications, 24(3), p.319 - 334, 2010/08

https://doi.org/10.1177/1094342009352483

In order to explore quantum dynamics of coupled Josephson junctions, we develop a program solving directly the time-dependent Schrdinger equation by diagonalizing the Hamiltonian matrix and obtaining its ground and multiple low-lying excitation states. The Schrdinger equation is defined on grids, in which is the number of grid points discretized on a characteristic phase space of each junction and is the number of coupled junctions. In this paper, the calculated maximum system is that and , i.e. the number of degrees of freedom reaches (=4,294,967,296). We examine possible effective numerical schemes and make a parallel tuning to optimize the communication on the Earth Simulator. We sustain floating-point operation performance exceeding 20% of the peak on 512 nodes (4,096 PEs). From systematic calculations, we find a new concept that "quantum-assisted synchronization" occurs with downsizing the junction plane. This is a discovery adding a quantum flavor to the classical concept "synchronization".

Analysis of uranium in environmental samples by micro X-ray fluorescence spectroscopy using transition edge sensors

Yomogida, Takumi; Yamada, Shinya*; Ichinohe, Yuto*; Sato, Toshiki*; Hayakawa, Ryota*; Okada, Shinji*; Toyama, Yuichi*; Hashimoto, Tadashi; Noda, Hirofumi*; Isobe, Tadaaki*; et al.

no journal, , 

Biotite is known as a host phase that retains uranium (U) in uranium deposits at Ningyo-Toge and Tono, and it is expected that the distribution of U in biotite will provide insight into the concentration and long-term immobilization of U. However, biotite contains rubidium (Rb), which interferes with X-ray fluorescence analysis, making it difficult to accurately determine the distribution of U-Rb in biotite by measurement using a conventional solid state detector (SSD). In this study, we developed a method to use a transition edge sensor (TES) as a detector in microbeam X-ray fluorescence analysis, which enables us to detect X-ray fluorescence with an energy resolution of about 20 eV and to obtain a Rb K line at 13.373 keV and a U L line at 13.612 keV can be completely separated. Therefore,the developed method enables us to accurately determine the distribution of U-Rb in biotite.

Elucidation of the reduction of uranium in biotite by advanced X-ray spectroscopy

Yomogida, Takumi; Yamada, Shinya*; Ichinohe, Yuto*; Sato, Toshiki*; Hayakawa, Ryota*; Okada, Shinji*; Toyama, Yuichi*; Hashimoto, Tadashi; Noda, Hirofumi*; Isobe, Tadaaki*; et al.

no journal, , 

The reduction of uranium on biotite was studied to obtain insight into the immobilization of uranium in the environment. The chemical species of uranium in biotite were studied using a superconducting transition edge sensor and an X-ray emission spectrometer to remove interference from rubidium in biotite. As a result, the speciation of uranium in biotite collected from former uranium deposits was possible. The XANES spectra of the biotite indicated that the uranium in the biotite was partially reduced.