Measurement of the Sub-nanometer Vibration Amplitudes Using 57Fe Synchrotron Mossbauer Source

The sub-nanometer amplitudes of the samples vibrated with high frequencies were measured by 57Fe Mossbauer spectroscopy using a nuclear Bragg monochromator and focusing optics. The Mossbauer spectra of the vibrated single-line absorber showed comb-like absorption peaks due to the frequency modulation of the gamma rays, and the amplitudes of the absorbers were determined by the sideband intensities. We used the stainless-steel foil glued on the quartz crystal or the polyvinylidene fluoride (PVDF) film as samples. The mean value and the variance of the amplitude in sub-nanometer order were obtained for the irradiated area of 100 μm diameter in the sample. We could obtain the sub-nanometer amplitude with almost zero variance, using the 57Fe synchrotron Mossbauer source and focusing optics for the PVDF film. Therefore, this method makes it possible to produce the high-quality coherent frequency-modulated gamma rays. This method is useful for the control of gamma rays. This work will advance X-ray quantum optics and quantum technology applications using a single gamma photon.journal articl

Single-Shot Laser-Driven Neutron Resonance Spectroscopy for Temperature Profiling

The temperature measurement of material inside of an object is one of the key technologies for control of dynamical processes. For this purpose, various techniques such as laser-based thermography [1] and phase-contrast imaging thermography [2] have been studied. However, it is, in principle, impossible to measure the temperature of an element inside of an object using these techniques. One of the possible solutions is measurements of Doppler brooding effect in neutron resonance absorption (NRA) [3]. Here we present a method to measure the temperature of an element or an isotope inside of an object using NRA with a single neutron pulse of approximately 100 ns width provided from a high-power laser. We demonstrate temperature measurements of a tantalum (Ta) metallic foil heated from the room temperature up to 617 K. Although the neutron energy resolution is fluctuated from shot to shot, we obtain exactly the temperature using a reference of a silver (Ag) foil kept to the room temperature. A free gas model well reproduces the results. This method enables element(isotope)-sensitive thermometry to detect the instantaneous temperature rise in dynamical processes.journal articl

Cryogenic solid deuterium target formation to realize highly pure deuteron acceleration by high-intensity laser

In recent years, laser-driven neutron sources have attracted attention for their applications such as nondestructive analysis and the production of medical radioisotopes. One of the efficient neutron production methods is the use of the 9Be(d, n)10B reaction on a beryllium target with deuterons accelerated by laser?plasma interactions, since this is an exothermic reaction. For efficient deuteron acceleration, we have developed a formation system for solid deuterium targets. A millimeter thick solid deuterium target can be formed with the system. Before the laser shot, the solid deuterium target in the laser chamber can be mechanically moved to the laser irradiation point. We have demonstrated deuteron acceleration by the LFEX laser, and a highly pure deuteron pulse with energies of up to 6.2 MeV was measured with a Thomson parabola ion spectrometer.journal articl

水の窓領域を超える軟X線高次高調波発生用赤外光パラメトリック増幅器を励起するための高出力イッテルビウムレーザー開発

本論文では高出力イッテルビウムレーザーの開発について報告する。高出力イッテルビウムレーザーは、イッテルビウムファイバーレーザーとパルス伸長器、Yb:KGW、Yb:YAG薄ディスク再生増幅器、パルス圧縮器からなり、出力は波長1030 nm、パルスエネルギー20.6 mJ、パルス幅923 fs、繰り返し周期5 kH（出力102.8 W）である。開発した高出力レーザーを縮退赤外光パラメトリック増幅器の励起光源として用いることで、変換効率~10%程度で波長2060 nmの極短パルスを発生可能となり、水の窓領域を超える軟Ｘ線高次高調波発生のために有望な光源となる。journal articl

Electric Potential Profile with Distributed Degradation in the Terminal Joint for ITER TF Coil System

ITER toroidal field coils are electrically connected to 68-kA main busbars (terminal joints). We propose the measurement of the electric potential distribution in a terminal joint using electrical probes (e-probe method) to inspect the contact resistance in the joint. In this study, we experimented with a mockup of a terminal joint. The test current was 20 A, and the electric potential was measured using the e-probe method at room temperature and 77 K. Nine different degradation patterns were prepared by distributing polyimide films in the joint interface. Next, we performed finite element analysis to investigate the detailed relationship between the electric potential distribution and contact resistance at 300 K and 77 K. In the numerical analysis, the same degradation patterns and test current as in the experiment were assumed. The analysis results agree with the experimental results. Different degradation patterns exhibit different electric potential profiles with 10-μV-scale differences. The analysis results also indicate that the e-probe method works when the contact resistance in the degraded area is larger than 1.0e-5 Ωmm^2 at 77 K and 300 K.journal articl

Realizing Laser-driven Deuteron Acceleration with Low Energy Spread via In-situ D2O-deposited Target

Generation of quasi-monocenergic ion pulse by laser-driven acceleration is one of the hot topics in laser physics. In this study, we present a new method for the In-situ deposition of an ultra-thin D2O layer on the surface of an aluminum foil target utilizing a spherical D2O capsule. Employing a 10^19 W/cm2 laser, we achieve the acceleration of 10.8 MeV deuterons with an energy spread of DE/E = 4.6% in the most favorable shot. The energy spread depends on the exposure time of the D2O capsule in the vacuum chamber. This method has the advantage that it is simple in setup and operation and potential of extending the applicability to other ion species.journal articl

Conceptual design of poloidal horseshoe limiter layout for JA DEMO

In the development of the JA DEMO fusion reactor, the proposed poloidal horseshoe limiter aims to mitigate the surface heat load localized on the breeding blanket. The limiter protrudes from the first wall toward the plasma to shade the blanket from the charged particles, which account for the majority of the surface heat load. To concretize the limiter design, this study presents a limiter layout that implements a concept that allows for sufficient cooling and remote maintenance. The limiter shape was determined by evaluating the surface heat load using 3-D magnetic field line tracing. A fully poloidal limiter with a width of 300 mm, which corresponds to 2.4 % of the FW area, was selected. The limiter heating, consisting of surface heat load and nuclear heating, was evaluated to discuss the required cooling, and the concept of a limiter cassette and modules for cooling was proposed. For the limiter replacement method, the outboard limiter is designed to be extracted from the upper port with the mounting segment. The inboard limiter is then grasped and transported to reach the upper port after the outboard limiter extraction. Both the inboard and outboard limiter are expected to be replaced without affecting other in-vessel components in this study.journal articl

Ultralong-Term High-Density Data Storage with Atomic Defects in SiC

There is an urgent need to increase the global data storage capacity, as current approaches lag behind the exponential growth of data generation driven by the Internet, social media, and cloud technologies. In addition to increasing storage density, new solutions should provide long-term data archiving that goes far beyond traditional magnetic memory, optical disks, and solid-state drives. Here, a concept of energy-efficient, ultralong, high-density data archiving is proposed, based on optically active atomic-size defects in a radiation resistance material, silicon carbide (SiC). The information is written in these defects by focused ion beams and read using photoluminescence or cathodoluminescence. The temperature-dependent deactivation of these defects suggests a retention time minimum over a few generations under ambient conditions. With near-infrared laser excitation, grayscale encoding and multi-layer data storage, the areal density corresponds to that of Blu-ray discs. Furthermore, it is demonstrated that the areal density limitation of conventional optical data storage media due to the light diffraction can be overcome by focused electron-beam excitation.journal articl

Carrier Systems of Radiopharmaceuticals and Their Application in Cancer Therapy

Radiopharmaceutical therapy (RPT) is emerging as a promising modality of treatment for tumor. RPT combines the specificity of carrier-based tumor localization with the cell killing properties of ionizing radiation. The carrier system of radiopharmaceuticals can precisely locate, guide radionuclides to the target, where radionuclides kill surrounding tumor cells by releasing ionizing particles. The effective application of radionuclides depends on the selection of an appropriate carrier system. Based on this, this paper firstly introduces therapeutic radionuclides and carrier systems for radiopharmaceuticals. Subsequently, we summarize common antibodies and antibody fragments used in radiopharmaceutical development, and outline the application of radiolabeled antibodies in cancer therapy, including lymphoma, colorectal cancer, and breast cancer. Furthermore, we review peptides employed as carrier systems, with emphasis given to the application of radiolabeled peptides in cancer therapy, including neuroendocrine neoplasms, prostate cancer, and glioma. Finally, we outline nanoparticles and other carrier systems that can be employed for targeted delivery of radionuclides, including nucleic acids, small molecules, and microspheres. Thus, this review will contribute to provide reference for the understanding carrier systems of radiopharmaceuticals, and further design better carrier systems to enhance efficacy and safety of radiopharmaceuticals in cancer therapy. Keywords: Radiopharmaceuticals, Carrier systems, Therapeutic radionuclides, Tumor, Targeted therapy, Applicationjournal articl

Channel Attention for Quantum Convolutional Neural Networks

Quantum convolutional neural networks (QCNNs) have gathered attention as one of the most promising algorithms for quantum machine learning. Reduction in the cost of training as well as improvement in perfor- mance are required for practical implementation of these models. In this study, we propose a channel attention mechanism for QCNNs and show the effectiveness of this approach for quantum phase classification problems. Our attention mechanism creates multiple channels of output state based on measurement of quantum bits. This simple approach improves the performance of QCNNs and outperforms a conventional approach using feed-forward neural networks as the additional postprocessing.journal articl