Yuuko Fukazawa

type:Article 本研究は,「GIGAスクール構想」の実現のために「ソフト」面に焦点をあて,デジタル教科書ならではの学びの充実をはかり,将来の学習者用デジタル教科書の有効な利活用も視野に入れつつ,現在配布されている指導者用デジタル教科書を用いた数学と理科の大学及び附属校の授業での利活用を含めたICTを効果的に活用する学習活動や教材化のための素案及び指導者用デジタル教科書を用いた授業実践の分析・考察を行うことを目的とする。 The purposes of this study are the following two points: (1) To focus on the soft wear aspects in order to realize the GIGA school concept and to enhance the learning that only digital textbooks can provide. (2) To analyze and discuss learning activities and teaching materials that effectively utilize ICT, including the use of digital textbooks for teachers in mathematics and science classes at universities and attached schools, as well as classroom practices using digital textbooks for teachers.

To observe specular oscillations in ion-surface scattering originating from layer-by-layer desorption of an electron stimulated desorbed (ESD) surface, a 15 keV proton beam was impinged on the surface with an angle of incidence less than 1°. We prepared an experimental system to examine the scattering yields of reflecting protons by conveniently employing a fluorescent screen to view scattering yields (scattering patterns) and a commercial digital camera for yield measurements. Because the present energy of the proton beam was too low to illuminate the screen, a micro-channel plate was inserted in front of the screen. Measurements with electron irradiation show obvious damping specular oscillations the widths of angular distributions of scattered protons simultaneously oscillated with increasing electron fluence. From the measured periods of the oscillations, the ESD rates of thermal desorption from KBr(001) at 1.5 keV electrons irradiation were obtained for sample temperatures.

The surface morphology of KBr (001) irradiated by electrons is observed by first decorating the surface with Au particles and then replicating it with C foils. For the electron irradiation and the subsequent decoration, we integrated an electron-beam gun and a vacuum evaporator. The sample surface was irradiated by a 1.5 keV electron beam small Au particles were then evaporated onto the surface. Although the decorated sample was prepared in an ultra-high vacuum condition, the C foil was evaporated in a separate high-vacuum evaporator. To avoid deliquescence of the sample surface, contact between the sample and the ambient air was minimized by transporting the sample between the two vacuum chambers in a N2-gas-filled enclosure. Imaging the surface with a transmission electron microscope revealed many rectangular monolayer pits. The mean area of the pits and the associated standard deviation are presented versus temperature the mean pit area increases with temperature.

We introduce our handmade image intensifer for visualizing the beam profiles of accelerated ion beams having energy and current in the order of keV and nano-amperes, respectively. The simple image intensifer comprising stainless steel meshes and a fluorescent screen has been designed for the transport of mm-size ion beams. The intensifer is easy to install in the beamline of a vacuum setup, because it is designed to attach on a conflat flange of ICF70. We have used the image intensifer to observe the beam profiles of the ion beams transported from the ion source to an ultra-high vacuum chamber. Through the use of the image intensifer, bright images were obtained, and it was concluded that the intensifer is useful for observing the profiles of the beams having current densities greater than 0.1 nA mm-2.

Growth forms of Au particles prepared by vacuum evaporation methods on KBr(001) and KCl(001) substrates with two types of surface steps prepared by thermal sublimation and by electron stimulated desorption are studied by using a carbon backing method with a transmission electron microscope. Spiral steps of monoatomic height have been prepared on the substrate surfaces by heat sublimation. Epitaxial Au particles with pyramidal shapes and other multiply twined particles are grown by the vacuum evaporation on the substrates at temperatures of 50-450°C. The size distributions of the particles on the substrates are reported and the typical size is measured to be smaller than 20×20 nm2. The ratio of populations of the multiply twined particles along the KBr steps is increased compared with that on the flat area. However, this increase in the ratio is not observed for particles grown on KCl. Additionally, step assemblies are prepared by electron stimulated desorption (ESD). The dependence of the size distributions of the Au particles grown on the substrates on electron Influence is measured for the ESD surfaces. With increasing electron Influence, the peak particle distribution size becomes smaller and particles smaller than 1 nm are observed.

We have examined the surface-channeling of 550 keV protons on electron-bombarded KBr(001) surfaces at grazing incidence. On the surface, electron-stimulated desorption (ESD) resulting from the irradiation of 5 keV electrons changes the surface morphology. In order to investigate the change of the surface morphology, the luminous intensity distributions observed on a fluorescent screen (scattering patterns) of the reflected protons under the surface-channeling conditions are measured. Normalized specular intensity of the protons oscillates, and the results of computer simulations show that the period of the intensity oscillation agrees with the period of layer-by-layer desorption. The measured period of the oscillation is comparable to the simulated one, i.e., the period of the desorption, however, the measured amplitude of the oscillation is weak. This shows that the layer-by-layer desorption of the experimental surface is observed but is not as remarkable as that of the perfect surface introduced in the simulation. (C) 2013 Elsevier B.V. All rights reserved.

Trajectories of fast (0.55 MeV) protons impinging under planar surface channeling conditions with an angle of incidence of several mrad are calculated on KBr(001) surfaces decorated by electron stimulated desorption (ESD). Two-dimensional angular distributions of protons scattered on the surface are obtained. In order to calculate trajectories, a computational technique is needed to form a set of morphologies of the surfaces according to the electron ‰uence. In our method, an assumption is made that the topmost atoms on the low coordinate sites are easily emitted by the ESD processes5). By choosing parameters introduced in the method, the oscillatory behavior of the desorption yields demonstrated by other groups is reproduced2). The resulting peak intensity of the re‰ected protons from the trajectory on the ensemble of surfaces with varying electron ‰uence oscillates as the electron ‰uence increases. Corresponding angular distributions of re‰ected protons have been measured on the electron irradiated KBr(001) surfaces, and a similar oscillation can be seen on the scattered yields with weak amplitudes.

Surface-channeling at grazing incidence of 550 keV protons on electron-bombarded KCl(001) and KBr(001) surfaces is investigated. In order to derive step density of the surfaces as a proportional function of electron-fluence lying in a range below 3×10 15 cm -2, intensity distributions (scattering patterns) of reflected protons on a fluorescent screen are observed. With increasing the fluence, the scattering patterns shift to lower scattering angle. The peak-angles of the luminous intensity are compared with calculated results of computer simulations. For both KCl and KBr surfaces, the electron fluence of 1.0×10 15 cm -2 is equivalent to the density of monolayer steps of 1.3×10 5 cm -1 piled upon in the simulation. Copyright © 2002 - 2012 Hogrefe Publishing.

To demonstrate experimental evidence caused by the lattice strain that was induced by the surface steps introduced by electronic stimulated desorption of ionic-crystals, the ion scattering experiment has been performed. Surface-channeling of protons incident with 5 mrad on an electron-irradiated KBr(001) surface is investigated using a 0.55 MeV beam of protons. The direction of the incident beam is adjusted along the &lt 100&gt channeling condition and the channeling-dips of the scattering yields are observed. The electron dose-dependence of the minimum yields (χmin) and widths of the dips (φ1/2) are compared with those measured on a KCl (001) surface. For the results of the χmin and φ1/2, results of KBr and KCl show similar dependence on the irradiation dose. For the both surfaces, two small peaks appear in symmetric positions on the channeling-dips. Peak-separations between the two peaks and widths of the peaks increase with the irradiation dose. Although no difference of the lattice strain induced on the two surfaces is detected only by the present experimental results, slight difference between the results for the two surfaces is observed and it is expected to be related with experimental evidence to demonstrate the lattice strain.

Surface-channeling of protons incident with 5 mrad on an electron-irradiated surface is investigated using a 0.55 MeV beam of protons. The target surface is KCl(0 0 1), which is damaged by electron-stimulated desorption with 5 keV electron irradiation. The direction of the incident beam is adjusted along the < 1 0 0 > and < 1 1 0 > channeling conditions and the channeling-dips of the scattering yields are observed. The irradiation dose-dependence of the minimum yields and widths of the dips is measured. Two dips are compared, i.e., for the < 1 0 0 > and < 1 1 0 > channelings. By increasing the irradiation dose up to 2 x 10(16) cm (2), the dip around the < 1 0 0 > axis becomes opened, but that of the < 1 1 0 > axis becomes shallow. The irradiated surfaces are observed to have many overlapped terraces of sub-micron with monolayer steps. The surface morphology deformed by the irradiation effects to truncate trajectories of the < 1 0 0 > channeling protons. This roughness of the surface is more effective for the trajectories of the < 1 1 0 > channeling protons. The protons incident on the rough surface along the < 1 1 0 > axis are not reflected from the atomic row but reflected by a potential of the surface with steps. Results by a simple computer simulation of the trajectories of protons at stepped surfaces also indicate the scattering processes. (C) 2009 Elsevier B. V. All rights reserved.

Surfaces of KCl crystals irradiated uniformly by scanning of 5 keV beam of electrons collimated with one direction are observed by an atomic force microscope (AFM). The irradiation doses are in the range up to 10¹⁶ cm^-2. The surfaces remain many overlapped terraces of sub-micron with random orientations. They are hard to be associated with the square pits observed in well known layer by layer desorption measurements in the dose range of 10¹⁴ cm^-2. The desorption process is simulated by a model based on the assumption that the low-coordinated sites act as the precursors for desorption. We have introduced parameters into this model to reproduce the oscillating structure of the particle-yields of the layer by layer desorption. The resulting final morphology in the dose range of 10¹⁶ cm^-2 shows that many overlapped terraces are created with random orientations, whose terrace-lengths are small compared with that observed. The morphologies show that the process assumed to reproduce the layer by layer desorption can lead the multi-layer steps on the surface.<br>

The surfaces of KCl crystals were sputtered by irradiation with 5 keV electrons (500 mu A/m(2)), in order to create a high density of surface steps. Energy loss distributions of 550 keV protons at glancing angle incidence scattered from the (001) surface were then measured for random (100 mrad off &lt; 100 &gt; direction) and surface-channeling (&lt; 100 &gt; direction) conditions. The surfaces were examined using atomic force microscope (AFM) in air. The measured energy spectra of protons were compared with those calculated by computer simulation. For random incidence, the fraction of the projectiles which penetrate through the surface increases with increasing dose of electron-irradiation. These protons pass through the steps both at the entrance and the exit. For the case of channeling incidence, this fraction decreases with increasing electron-irradiation dose in the dose range from 10(19) m(-2) to 10(20) m(-2), because the projectiles do not necessarily pass through the surface steps. AFM observations show that there are many steps of several to several tens of monolayers&apos; height on the surface for samples irradiated with doses of more than 1 x 10(20) m(-2). (C) 2008 Elsevier Ltd. All rights reserved.

Angle-dependent energy losses of well-collimated 5-10 keV protons scattered in collisions with CH4, CH6, and C3H8 molecules have been measured. The thickness of the targets is less than 20mPa.m, which is determined from the measured neutral fraction in the scattered beam and the charge-transfer cross sections reported by another group. The scattered protons have slightly expanded tails of the angular distribution. The measured energy losses increase with the angle. The stopping cross sections, which are obtained by integrating the angle-dependent energy losses over the square of the angle, agree well with the compilation values of SRIM-2006. The stopping cross sections are found to have a non-linear relationship with the size of target molecules. The contribution of a carbon atom attached by two hydrogen atoms of a heavier molecule becomes relatively small. This molecular size effect is enhanced with the decreasing energy of protons. Meanwhile, for protons that are deflected significantly, the molecular size effect is decreased.

To understand the various surface morphology of ionic crystal that is irradiated by electrons, the surface channeling technique of ion beam is used. The energy spectra and the channeling-dips are measured by the detection of 550 keV proton beam scattered from the electron-irradiated surface of KCl(001). After the electron-irradiation, the roughness of the sample surface is observed by an Atomic force microscope. The results of these experiments are compared with the calculated results of a computer simulation. The proton beam which directed along the 〈100〉 axis penetrates into the crystal and is scattered at large angle. This result is due to the surface morphology changed by the electron-stimlated-desorption.

Energy loss spectra and angular distributions of 610 keV protons scattered on the (001) surfaces of the ion crystals are measured. The angle of incidence of protons is smaller than 13 mrad. The surfaces have been in-situ irradiated uniformly and the other nonuniformly so that its upstream side for the incident protons is removed preferentially. The surface damages created by the irradiation are observed by an atomic force microscopy (AFM) in air. With increasing the irradiation dose, the energy losses and the peak angles of scattering of the scattered protons are plotted. The results depend largely on the distribution of damages, and are compared with calculated results by a computer simulation. It is found that the change of the angular distributions depends not only on the distribution of damages but also on the angle of incidence of protons to the surface.

これまでに製作してきた十数個の物理教材を同時に展示し，小さな科学館を作った。科学館は本学の大学祭（五月祭・神霜祭）で企画し，ここで行ったアンケートから，教材の評価をし，それぞれの教材について最も有効な活用方法について考察をした。