Spectroscopic Studies of Limb Spicules. I. Radial and Turbulent Velocities

We made high-resolution spectroscopic observations of limb-spicules in H-alpha using the Vertical Spectrograph of Domeless Solar Telescope at Hida Observatory. While more than half of the observed spicules have Gaussian line-profiles, some spicules have distinctly asymmetric profiles which can be fitted with two Gaussian components. The faster of these components has radial velocities of 10 - 40 km/s and Doppler-widths of about 0.4 A which suggest that it is from a single spicule oriented nearly along the line-of-sight. Profiles of the slower components and the single-Gaussian type show very similar characteristics. Their radial velocities are less than 10 km/s and the Doppler-widths are 0.6 - 0.9 A. Non-thermal "macroturbulent" velocities of order 30 km/s are required to explain these width-values.Comment: 13 pages, 12 figures, to be published in Publications of the Astronomical Society of Japa

Self-written waveguides in photopolymerizable resins

We study the optically-induced growth and interaction of self-written waveguides in a photopolymerizable resin. We investigate experimentally how the interaction depends on the mutual coherence and relative power of the input beams, and suggest an improved analytical model that describes the growth of single self-written waveguides and the main features of their interaction in photosensitive materials.Comment: 3 pages, 3 figure

Forest Radioecology in Fukushima

This is an open access book that provides holistic information on the radioactive contamination of forests. Topics are highly interdisciplinary, ranging from the dynamics of radioactive cesium in forest ecosystems to the radiation protection or the socio-economic aspects of radiation effects. It is designed to help people understand the radioactive contamination in forests and provide hints of how to cope with it and restore their livelihoods. The book is characterized by its well-balanced structure that allows the reader to understand the whole picture without going into too much scientific content. After explaining the basics of radioactive materials and radiation, the book illustrates the radioactive contamination of forests, it also describes the impacts on the forestry and life of local people and the measures taken by. Few books address the concerns about how to deal with radioactive contamination of forests and the future perspectives. In this book, people can learn all about the Fukushima nuclear accident of forests, forest products, and people with abundant reference materials. In addition, the book contains four memoirs contributed by Japanese and European researchers that graphically record what the researchers thought and how they acted in the chaos of the aftermath of the accident. In 2021 that marking the 10th anniversary of the Fukushima nuclear accident and the 35th anniversary of the Chernobyl accident, nuclear disasters are in the spotlight more than ever. This thought-provoking book on how to prepare for a severe nuclear accident is suitable for sharing with people all over the world as a lesson on the next nuclear accidents, now that the number of nuclear power plants is still increasing. The translation of this work was done with the help of artificial intelligence (machine translation by the service DeepL.com). Intensive improvements were subsequently made by the authors throughout the text to ensure accuracy of expression and contents and to enhance the clarity

Surface Nanofabrication in Photosensitive Polymers at the diffraction limit of light and down to 47 nm by Metal Tip-Enhanced Near Field light : Light Induced Nanomovement of Polymers

This paper discusses surface nanofabrication in azo-polymers. Nanoscale polymer movement is induced by a tightly focused laser beam in an azo-polymer film just at the diffraction limit of light. The deformation pattern which is produced by photoisomerization of the azo dye is strongly dependent on the incident laser polarization and the longitudinal focus position of the laser beam along the optical axis. The anisotropic nanofluidity of the polymer film and the optical gradient force played important roles in the light induced polymer movement. We also explored the limits of the size of the photo-induced deformation, and we found that the deformation depends on the laser intensity and the exposure time. The smallest deformation size achieved was 200 nm in full width of half maximum; a value which is nearly equal to the size of the diffraction limited laser spot. Beyond the limit of light diffraction, a nano protrusion was optically induced on the surface of the films by metal tip enhanced near-filed illumination. A silver coated tip was located inside the diffraction limited spot of a focused laser beam (460 nm), and an enhanced near-field, with 30 nm light spot, was generated in the vicinity of the tip due to localized surface plasmons. The incident light intensity was carefully regulated to induce surface nanodeformation by such a near-field spot. A nano protrusion with 47 nm full width of half maximum and 7 nm height was induced with a resolution beyond the diffraction limit of the light. The protrusion occurs because the film is attracted towards the tip end during irradiation. At the top of the protrusion, an anisotropic nanomovement of the polymer occurs in a direction nearly parallel to the polarization of the incident light, and suggests the existence at the tip end of not only a longitudinal, i.e., along the tip long axis, but also a lateral component of the electric field of light. The azo-polymer film helps map the electric field in the close vicinity of the tip.This paper discusses surface nanofabrication in azo-polymers. Nanoscale polymer movement is induced by a tightly focused laser beam in an azo-polymer film just at the diffraction limit of light. The deformation pattern which is produced by photoisomerization of the azo dye is strongly dependent on the incident laser polarization and the longitudinal focus position of the laser beam along the optical axis. The anisotropic nanofluidity of the polymer film and the optical gradient force played important roles in the light induced polymer movement. We also explored the limits of the size of the photo-induced deformation, and we found that the deformation depends on the laser intensity and the exposure time. The smallest deformation size achieved was 200 nm in full width of half maximum; a value which is nearly equal to the size of the diffraction limited laser spot. Beyond the limit of light diffraction, a nano protrusion was optically induced on the surface of the films by metal tip enhanced near-filed illumination. A silver coated tip was located inside the diffraction limited spot of a focused laser beam (460 nm), and an enhanced near-field, with 30 nm light spot, was generated in the vicinity of the tip due to localized surface plasmons. The incident light intensity was carefully regulated to induce surface nanodeformation by such a near-field spot. A nano protrusion with 47 nm full width of half maximum and 7 nm height was induced with a resolution beyond the diffraction limit of the light. The protrusion occurs because the film is attracted towards the tip end during irradiation. At the top of the protrusion, an anisotropic nanomovement of the polymer occurs in a direction nearly parallel to the polarization of the incident light, and suggests the existence at the tip end of not only a longitudinal, i.e., along the tip long axis, but also a lateral component of the electric field of light. The azo-polymer film helps map the electric field in the close vicinity of the tip

Size dependent nanomechanics of coil spring shaped polymer nanowires

Direct laser writing (DLW) via two-photon polymerization (TPP) has been established as a powerful technique for fabrication and integration of nanoscale components, as it enables the production of three dimensional (3D) micro/nano objects. This technique has indeed led to numerous applications, including micro- and nanoelectromechanical systems (MEMS/NEMS), metamaterials, mechanical metamaterials, and photonic crystals. However, as the feature sizes decrease, an urgent demand has emerged to uncover the mechanics of nanosized polymer materials. Here, we fabricate coil spring shaped polymer nanowires using DLW via two-photon polymerization. We find that even the nanocoil springs follow a linear-response against applied forces, following Hooke’s law, as revealed by compression tests using an atomic force microscope. Further, the elasticity of the polymer material is found to become significantly greater as the wire radius is decreased from 550 to 350 nm. Polarized Raman spectroscopy measurements show that polymer chains are aligned in nanowires along the axis, which may be responsible for the size dependence. Our findings provide insight into the nanomechanics of polymer materials fabricated by DLW, which leads to further applications based on nanosized polymer materials

Study of hadron interactions in a lead-emulsion target

Topological and kinematical characteristics of hadron interactions have been studied using a lead-emulsion target exposed to 2, 4 and 10 GeV/c hadron beams. A total length of 60 m $\pi^-$ tracks was followed using a high speed automated emulsion scanning system. A total of 318 hadron interaction vertices and their secondary charged particle tracks were reconstructed. Measurement results of interaction lengths, charged particle multiplicity, emission angles and momenta of secondary charged particles are compared with a Monte Carlo simulation and appear to be consistent. Nuclear fragments emitted from interaction vertices were also detected by a newly developed emulsion scanning system with wide-angle acceptance. Their emission angle distributions are in good agreement with the simulated distributions. Probabilities of an event being associated with at least one fragment track are found to be greater than 50% for beam momentum $P > 4$ GeV/c and are well reproduced by the simulation. These experimental results validate estimation of the background due to hadron interactions in the sample of $\tau$ decay candidates in the OPERA $\nu_{\mu} \to \nu_{\tau}$ oscillation experiment.Comment: 14 pages, 11 figure

A New Output Current Measurement Method with Tiny PCB Sensors Capable of Being Embedded in an IGBT Module

This paper proposes a new output current measuring method using tiny printed-circuit-board (PCB) current sensors. The method will make it possible to install the PCB current sensors in an insulated-gate bipolar transistor (IGBT) module. The PCB sensor picks up a switching current flowing through an IGBT chip, and then a combination of a digital circuit based on field-programmable gate array and an integrator circuit reproduces the output current of an inverter from the switching current. A proof-of-concept experimental verification is carried out using a buck converter, which verifies that the proposed method detects a dc component of the output current as well as a ripple component although the PCB sensor is based on the so-called Rogowski coil

Exploration of new superconductors and functional materials and fabrication of superconducting tapes and wires of iron pnictides

This paper reviews the highlights of a 4-years-long research project supported by the Japanese Government to explore new superconducting materials and relevant functional materials. The project found several tens of new superconductors by examining ~1000 materials, each of which was chosen by Japanese team member experts with a background in solid state chemistry. This review summarizes the major achievements of the project in newly found superconducting materials, and the wire and tape fabrication of iron-based superconductors. It is a unique feature of this review to incorporate a list of ~700 unsuccessful materials examined for superconductivity in the project. In addition, described are new functional materials and functionalities discovered during the project.Comment: 141 pages, 127 Figures, 14 Tables, 535 Refrence