Territory of Research
A territory of research at our laboratory can be mainly classified into three fields: (1) applied physics, (2) theoretical physics, and (3) physics education. The research problems with which our laboratory is now occupied are as follows respectively.
Recent Publications
Masaya Sengoku, Shinya Sawai and Tamotsu Ohno:
Transmission Electron Microscopy of Fine Aromatic Hydrocarbon ParticlesMicron vol.32 Issue 4(2001) pp.447-448
Fine perylene and pyrene particles were produced by evaporation in helium gas. The particles were sensitive to electron beam radiation. The pyrene particle sublimed under observation. These difficulties were cleared up by reducing electron beam exposure and sandwiching a specimen between two Formvar films. The fine perylene particles were rectangular or hexagonal plates of about 50 nm thick. The size was about 200-2,000 nm. The fine pyrene particles were polymorphic with a size of about 300-2,000 nm. The crystal forms of perylene and pyrene particle were determined from the electron diffraction pattern to be a-perylene and pyrene I, respectively.
Masaya Sengoku, Tamotsu Ohno and Tatsuo Arii:
High-Voltage and High-Resolution Electron Microscopy of Fine Organic Particles
Proceedings of The 7th Asia-Pacific Electron Microscopy Conference, Physical Sciences, Singapore International Convention & Exhibition Centre, Suntec City, Singapore (2000.6) pp.233-234.
Crystal structure and morphology of fine metal particles have been determined by using electron microscopy and electron diffraction. Nevertheless, there are few reports of such studies on individual fine organic particles. It is caused mainly by extreme sensitivity of organic compounds to electron radiation. The previous study made clear that the higher voltage electron microscopy combined with the use of image plates is advantageous for observation of radiation sensitive organic crystals. Using the same technique, the high-resolution image of fine organic particles was observed.
Masanori Tanaka, Shinya Sawai, Masaya Sengoku, Manabu Kato, and Yasuaki Masumoto:
Luminescence properties of ZnS phosphor nanocrystals prepared by the laser-induced gas-evaporation method
Journal of Applied Physics. vol.87 Issue 12 (2000) pp.8535-8540
Nanocrystalline particles of ZnS:(Ag, Al) semiconductor phosphor, whose sizes are mostly 3–5 nm in diameter, are prepared by the gas-evaporation method with cw CO2 laser heating. The Raman scattering spectrum as well as the transmission electron microscope observation demonstrates that the crystallization of the nanoparticles was caused successfully through the gas-phase condensation. Under irradiation of ultraviolet light, the nanoparticles exhibit blue luminescence, as in the case of the starting material of ZnS:(Ag, Al) bulk powder. The peak of the luminescence spectrum of the nanoparticles shifts to lower energy with increasing delay time and also with decreasing excitation intensity, showing that the luminescence originates from the donor–acceptor pair recombination. However, it is concluded that the luminescence of the nanoparticles is not ascribed to the blue Ag luminescence mechanism responsible for the luminescence of the bulk powder, by taking into account the spatial confinement of an electron trapped at the donor and a hole at the acceptor. It is argued that the luminescence mechanism of the nanoparticles is the so called self-activated luminescence, which involves zinc vacancies.
Masaya Sengoku and Tamotsu Ohno:
Quantitative Measurement of Electron Beam Damage to Langmuir-Blodeget Films of Behenic Acid Using Imaging Plates
Bulletin of the Liberal Arts and Science Course, Aichi Medical University No.26 (1999) pp.1-5 (in Japanese).
Masaya Sengoku, Shinya Sawai and Minoru Dohi:
Gas Evaporation of Zinc under Low Gravity with a Drop Capsule
Japanese Journal of Applied Physics Vol.38 No.4 (1999) pp.2064-71.
Fine zinc particles were produced in an argon gas atmosphere and in a helium gas atmosphere of 1.33*104 Pa without thermal convection. To investigate the initial process of crystal growth, particles deposited at various places and at different moments during evaporation were collected. The shape and size of the particles were observed using a scanning electron microscope. When the evaporation time increased, the mean size of the deposited particles decreased in the argon gas atmosphere, while it increased in the helium gas atmosphere. These experimental results can be interpreted in terms of the assumption that nucleation and crystal growth are dominated only by the diffusion of vapor from the evaporation source.
Tamotsu Ohno, Masaya Sengoku and Tatsuo Arii:
Dependence of electron beam damage in organic crystals on accelerating voltage
Electron Microscopy 1998 (Edited by H.A. Calderon Benavides & J. Yacaman, Institute of Physics Publishing, London, 1998) Vol.2, pp.835-836.
The rate of fading of electron diffraction pattern from monolayer crystals of behenic acid was measured at the accelerating voltage over the range 100 ?1,000 kV, using a mechanical shutter system for giving accurate electron exposures and imaging plates for recording electron diffraction patterns. The extinction dose increased with increasing accelerating voltages and it was about six times greater at 1,000 kV than at 100 kV. This means that we can observe the diffraction pattern several times longer at 1,000 kV than at 100 kV. Although the relative value of the electron intensity obtained from the imaging plate reduces to about 1/6 of that at 100 kV, the DQE value for the electron number fluctuation is relatively high (0.4). Therefore, the greater critical dose at the higher accelerating voltage is probably more useful to record the diffraction pattern of radiation sensitive organic crystals.
Tamotsu Ohno:
Fading and broadening of electron diffraction spot from beam-damaged multiple monolayer films
Journal of Microscopy Vol.184, Pt.1, (1996) pp.17-21.
In contrast to the increase of the extinction dose for thick specimens, observed broadening rates of diffraction spots from behenic acid multiple monolayers were independent of specimen thickness. This result leads to a conclusion that specimens are always decaying at the same rate although the periodicity of crystals still remains in thick specimens. The conclusion is interpreted by the radiation damage mechanism based on longitudinal motions of long chain molecules. For the evaluation of beam damage effect the broadening rate and the extinction dose should be used as indicator for the radiation sensitivity of crystals and for the possibility of observing diffraction patterns, respectively.
Yoshio Koide, Hideo Fusaoka:
Evolution of the Yukawa coupling constants and seesaw operators in the universal seesaw model
Physical Review D 64 No.5 (2001.9) 053014-1 - 053014-18
The general features of the evolution of the Yukawa coupling constants and seesaw operators in the universal seesaw model with det M_F=0 are investigated. Especially, it is checked whether the model causes bursts of Yukawa coupling constants, because in the model not only the magnitude of the Yukawa coupling constant (Y_L^u)_{33} in the up-quark sector but also that of (Y_L^d)_{33} in the down-quark sector is of the order of one, i.e., (Y_L^u)_{33} \sim (Y_L^d)_{33} \sim 1. The requirement that the model should be calculable perturbatively puts some constraints on the values of the intermediate mass scales and tan\beta (in the SUSY model).
Ambar Ghosal, Yoshio Koide, Hideo Fusaoka:
Lepton flavor violating Z decays in the Zee model
Physical Review D 64 No.5 (2001.9) 053012-1 - 053012-10
We calculate lepton flavor violating (LFV) Z decays Z \to {{e_i^\pm}}e_j^\mp (i, j = e, \mu, \tau ; i\neq j) in the Zee model keeping in view the radiative leptonic decays e_i\to e_j\gamma (i = \mu, \tau ; j = e, \mu ; i\neq j), \mu decay and anomalous muon magnetic moment (\mu AMM). We investigate three different cases of Zee f_{ij} coupling (A) f_{e\mu}^2 = f_{\mu\tau}^2= f_{\tau e}^2, (B) f_{e\mu}^2 \gg f_{\tau e}^2 \gg f_{\mu\tau}^2, and (C) f_{\mu\tau}^2 \gg f_{e\mu}^2 \gg f_{\tau e}^2 subject to the neutrino phenomenology. Interestingly, we find that, although the case (C) satisfies the large excess value of \mu AMM, however,it is unable to explain the solar neutrino experimental result, whereas the case(B) satisfies the bi-maximal neutrino mixing scenario, but confronts with the result of \mu AMM experiment. We also find that among all the three cases, only the case (C) gives rise to largest contribution to the ratio B(Z\to e^\pm\tau^\mp)/B(Z\to \mu^\pm \mu^\mp) \simeq {10}^{-8} which is still two order less than the accessible value to be probed by the future linear colliders, whereas for the other two cases, this ratio is too low to be observed even in the near future for all possible LFV Z decay modes.
Yoshio Koide and Hideo Fusaoka:
Universal Seesaw Mass Matrix Model with Three Light Pseudo-Dirac Neutrinos
Physical Review D 59-5, pp.053004-1 - 053004-8 (1999.3).
A universal seesaw mass matrix model, which
gives successful description of quark mass matrix in terms of lepton masses,
yields three ``sterile" neutrinos \nusi,
which compose pseudo-Dirac neutrinos \nui±ps\simeq
(\nui ± \nusi)/(2)1/2
together with the active neutrinos \nui (i=e,\mu,\tau).
The solar and atmospheric neutrino data areexplained by the mixings \nue\leftrightarrow
\nuse and \nu\mu\leftrightarrow \nus\mu,
respectively. In spite of such observations of the large mixing \sin2
2\theta\simeq 1 in the disappearance experiments, effective mixing parameters
\sin2 2\theta\alpha\beta in appearance experiments \nu\alpha\rightarrow\nu\beta
(\alpha, \beta = e, \mu, \tau) are highly suppressed.
Hideo Fusaoka and Yoshio Koide:
Updated Estimate of Running Quark MassesPhysical Review D 57 No.7 (1998.4) pp.3986-4001.
Stimulated by recent development of the
calculation methods of the running quark masses mq(\mu) and
renewal of the input data, for the purpose of making a standard table of mq(\mu)
for convenience of particle physicists, the values of mq(\mu)
at various energy scales \mu (\mu = 1 GeV, \mu = mc, \mu=mb,
\mu=mt and so on), especially at \mu = mZ,
are systematically evaluated by using the mass renormalization equations and
by taking into consideration a matching condition at the quark threshold.
Hideo Fusaoka and Yoshio Koide:
Updated Running Quark Mass ValuesMasses and Mixings of Quarks and Leptons
edited by Yoshio Koide (World Scientific, Singapore, 1998.1), pp. 18-29.
The running quark masses mq(\mu)
at various energy scales \mu (\mu = 1 {\rm GeV}, \ \mu = mq,
\ \mu = mZ and so on) are evaluated by using the mass
renormalization equations systematically. Also, those at energy scales \mu
higher than \mu = mZ (from \mu = 103 GeV to \mu =
1016 GeV) are evaluated by using the evolution equations of Yukawa
coupling constants for the standard model with a single Higgs boson.
Yoshio Koide and Hideo Fusaoka
Analytical Expressions of Masses and Mixings in a Democratic Seesaw Mass Matrix ModelProgress of Theoretical Physics 97-3 (1997.3) pp.459-477.
On the basis of a seesaw-type mass matrix model Mf\simeq
mLMF-1mR for quarks
and leptons, f, analytical expressions of the masses and mixings of the
fermions f are investigated. Here, the matrices mL
and mR are common to all f (up- and down-; quarks and
leptons), and the matrix MF characterizing the heavy fermion
sector has the form [(unit matrix)+ (democratic-type matrix)]. An application
to the quark sectors is discussed.
Yoshio Koide and Hideo Fusaoka:
Top Quark Mass Enhancement in a Seesaw-Type Quark Mass Matrix
Zeitschrift fur Physik C 71 (No.3) (1996.7) pp.459-467.
We investigate the implications of a seesaw type
mass matrix, i.e., Mf\simeq mLMF-1mR,
for quarks and leptons f under the assumption that the matrices mL
and mR are common to all flavors (up-/down- and
quark-/lepton- sectors) and the matrices MF characterizing
the heavy fermion sectors have the form [(unit matrix) + bf
(a democratic matrix)] where bf is a flavor parameter. We
find that by adjusting the complex parameter bf, the model
can provide that mt\gg mb while at the
same time keeping mu\sim md without
assuming any parameter with hierarchically different values between MU
and MD. The model with three adjustable parameters under the
``maximal" top quark mass enhancement can give reasonable values of five
quark mass ratios and four KM matrix parameters.
Hideo Fusaoka:
Quark Mass Relations in a Seesaw-Type Quark Mass Matrix Model
Hadron '95, Proceedings of the 6th International Conference on Hadron Spectroscopy,
edited by M. C. Birse, G. D. Lafferty,, and J. A. McGovern (World Scientific, Singapore, 1996.3), pp. 371-373.
A seesaw-type mass matrix Mf \simeq
mLMF-1mR for quarks
and leptons f is investigated where the matrix mL (mR
) has the diagonal matrix form represented by lepton masses. The
heavy fermion matrices MF (F=U,D,N,E
correspondingly to f =u,d,\nu,e) has the form (a
unit matrix ) +bf ei \betad
( a rank one matrix). Without assuming any hierarchically different
parameters, we explain mt \gg mb and mu
\simeq md. The model can predict reasonable quark mass
relations and Kobayashi-Maskawa matrix elements.
Yoshio Koide and Hideo Fusaoka
Seesaw-Type Quark and Lepton Mass Matrices and U(3)-Family Nonet Higgs Bosons
Bulletin of the Liberal Arts and Science Course No.22 (1995.12), pp.1-10, [Aichi Medical University].
A unified mass matrix model of quarks and
leptons with a seesaw-type form Mf=mMF-1m
is proposed on the basis of a non-standard Higgs scenario. The matrix m
is provided by U(3)-family nonet bosons \phi, and the matrix MF
is a mass matrix of heavy fermions Fi corresponding to the
ordinary fermions fi=\nui,ei,ui,di
(i=1,2,3). It is shown that a Higgs potential of \phi with a broken
U(3)-family symmetry leads to a desirable charged lepton mass formula when ME\propto
{\bf 1}. Then, phenomenologically desirable forms of heavy quark mass matrices
MQ (Q=U,D) are investigated.
Hideo Fusaoka and Yoshio Koide
Quark Mass Matrix with a Structure of a Rank One Matrix Plus a Unit MatrixModern Physics Letters A 10-4 (1995.4) pp.289-294.
A quark mass matrix model Mq=Me1/2OqMe1/2
is proposed where Me1/2={\rm diag}((me)1/2,(m\mu)1/2,(m\tau)1/2)
and Oq is a unit matrix plus a rank one matrix. Up- and
down-quark mass matrices Mu and Md are
described in terms of charged lepton masses and additional three parameters
(one in Mu and two in Md). The model can
predict reasonable quark mass ratios (not only mu/mc,
mc/mt, md/ms
and ms/mb, but also mu/md)
and Kobayashi-Maskawa matrix elements.
Hideo Fusaoka, Masaya Sengoku and Tamotsu Ohno:
Liberal and General Education at Medical Schools - Comments Based on Changes of Class Hours -
Journal of the Liberal and General Education Society of Japan Vol.22, No.2 (2000) pp.141-147 (in Japanese).
After a thorough revision of the Standards for the Establishment of Universities made the standards simpler and more flexible in 1991, curriculums for liberal and general education were reformed in many universities. Various reforms, such as reform of graduate schools and introduction of the fixed-term appointment of faculty members at universities, have been carried out since then. Furthermore, a plan to transform national universities into independent administrative institutions is being prepared. However, the reforms have been initiated without enough self-monitoring and self-evaluation in
many cases.
The reforms of the liberal and general education, which provided the starting point of the university reform, were surveyed in the case of medical schools. Based on the survey, it is discussed what liberal and general education should be
in the future. Class hours for the liberal and general education in 1989, 1997
and 1999 were investigated to compare the changes in the recent years(1997, 1999) with the state before making the standards more
flexible(1989). In 1999, the liberal and general education is given for an average of 1.4 years at national universities, for an average of 1.1 years at private universities. The class hours
for the liberal and general education are cut down by about 0.4 years in comparison to those in 1989. In particular, the class hours at the second year at university have been remarkably reduced. Although the present class hours are not enough, possible methods in the decreased class hours for the liberal and general
education at medical schools are discussed.
Tamotsu Ohno:
Guidance to Freshmen for Self-Learning - Some Problems and Solutions in Freshman Seminar for Medical Students -
Journal of the Liberal and General Education Society of Japan Vol.22, No.2 (2000) pp.136-140 (in Japanese).
Spiritless students have increased who do not understand the meaning of learning at university. Giving guidance to freshmen in how to learn at university is very important, because it may decide if they will spend substantial student life. It is effective as guidance that students see a teacher studying in front of them. A seminar is one of the best ways for it. The seminar for freshmen is especially important. We have carried out the freshman seminar for 19 years at Aichi Medical University. Although the seminar has been improved, some problems still remain. One of them is concerned with setting a suitable theme for freshmen. Generally, teachers choose the theme in the field of their research. Some themes were too difficult or unattractive for freshmen. We tried setting a new class for a campus tour. Before visiting a laboratory, students who attended the class should collect information about the laboratory and study on the research field of the laboratory. This process is very important to learn methods for self-learning with his/her interest. As a result of improvement in trial for two years, a high correlation in academic achievement between the class and other subjects was shown. The result leads to the conclusion that the campus tour is effective as the freshman seminar.
Hideo Fusaoka and Tamotsu Ohno:
Improvements of Seminar-Based Teaching in Liberal Arts Education and FD-Activities at a Medical School
Journal of the Liberal and General Education Society of Japan Vol.21, No.1 (1999) pp.95-99 (in Japanese).
Aichi medical university started "liberal arts seminar" for freshmen in 1982. To improve the seminar, all the teachers in the general education course had discussed many times for a few years. The improvement plan was carried out from 1997. Main points of the improvement were as follows: (1) the subject name was changed to "Basic Science Seminar"; (2) the attendance at each class was limited to 10; (3) students spend the first three weeks to choose a class; (4) a meeting for oral presentation is held and abstracts of the meeting are printed; (5) a new standard for evaluating the student's academic work was set up; and (6) the class teacher of the seminar doubles as an adviser. According to the students' evaluation of the new seminar, about 70 % of students were thinking that the seminar was useful and substantial. They were satisfied with the seminar and studied earnestly. On the other hand, about 20 % of students were feeling that the seminar was neither useful nor substantial. Furthermore, a little less than half the students answered that they did not take the seminar if it was not a required subject. It is necessary to make such students understand the meaning of the seminar and the meaning to learn at university anew. About 80 % of students supported the system that the class teacher of the seminar doubles as the adviser. It became clear in the process of discussion among the teachers about problems, which they had in common, that the work to improve the seminar played a role as the FD activity, although it was never expected at first. Cooperation among teachers in the course has increased since.
Tamotsu Ohno, Masaya Sengoku and Hideo Fusaoka:
A study of remedial education in physics for premedical students
Bulletin of the Liberal Arts and Science Course, Aichi Medical University No.25 (1998) pp.35-42 (in Japanese).
Hideo Fusaoka, Tamotsu Ohno, Satoshi Oga, Masaki Matsubara, Tadaharu Tsuge, Masaya Sengoku, Motoko Tagawa, Masumi Yasutomi, Yoshiaki Itoh, Chiharu Ando, Yoshitaka Obata, Tetsuo Watanabe and Junnin Kojima:
An attempt at seminar-based teaching in general education for premedical students
Bulletin of the Liberal Arts and Science Course, Aichi Medical University No.25 (1998) pp. 43-69(in Japanese).
Tamotsu Ohno, Hideo Fusaoka and Masaya Sengoku:
Differences in academic achievement of freshmen at premedical course in physics and remedial education
Journal of the Liberal and General Education Society of Japan Vol.19, No.2 (1997) pp.121-125 (in Japanese).
Most of students enter the university after they have learned only two subjects in three fields of science (physics, chemistry and biology) in the high school. Accordingly, they lack basic knowledge on the third subject, which is different in each student. In spite of the different background in science, premedical students are required to get credits for all of the three fields of science, because adequate knowledge on wide fields of science is necessary to study medical sciences. At Aichi Medical University there was a need of remedial education for students who do not have enough background to understand physics or biology. We began a new program 15 years ago. In the program, students are required to work at many exercises in the class. The program is effective to remedy the lack of background in physics.
Sawami Miyawaki et. al. and NEP members (include Hideo
Fusaoka):
Organization of Network for Education of Elementary Physics in University
Journal of the Liberal and General Education Society of Japan Vol.19, No.2 (1997) pp.132-137 (in Japanese).
We have organized sixty-four physicists in Japan and started a project named the Network for Education of Physics. The main purpose of the project is to promote the education of elementary physics in universities by supplying a huge public database of the teaching materials, methods, curricula, syllabuses, textbooks and so on to teachers and students through the Internet. For exchanging information thus accumulated, a World Wide Web server with a RAID has been prepared. The information concerning to the project will be available from this server through the Internet.
Masaya Sengoku, Hideo Fusaoka and Tamotsu Ohno:
Students’ evaluation of “Physics, Basic Seminar” and improvement in the seminar
Bulletin of the Liberal Arts and Science Course, Aichi Medical University No.24 (1997) pp.25-32 (in Japanese).
Hideo Fusaoka, Masaki Matsubara, Junnin Kojima, and Chiharu Ando:
General Education for the Premedical Students
Bulletin of the Liberal Arts and Science Course, Aichi Medical University No.24 (1997) pp.67-74 (in Japanese).
Kisei Kinoshita, Toshio Hyodo, Hideo Fusaoka and Shohei Kashiwamura:
Examples of the Modules of Demonstrations in Lectures
University Study No.17 (1996) pp.5-18 (in Japanese).
Kisei Kinoshita, Toshio Hyodo, Hidco Fusaoka and Shohei Kashiwamura:
Systematization of Modules for Demonstrations in Physics Lectures
University Study No.17 (1996) pp.189-198 (in Japanese).
Short time experiments for the demonstration in physics lectures are
elaborated and systematized into modules useful for university professors
including theorists unfamiliar with experiments.
Key Words ： handy demonstration，classroom
demonstration，module of demonstration.
Tamotsu Ohno:
Problems arising from the adoption of the credit system
Bulletin of the Liberal Arts and Science Course, Aichi Medical University No.23 (1996) pp.23-32 (in Japanese).
Tamotsu Ohno:
An attempt to check effects of lectures
Journal of the Liberal and General Education Society of Japan Vol.17, No.1 (1995), pp.117-121 (in Japanese).
Measuring effect of lectures is possible by checking correlation of scores on terminal examination with total learning time in class. We studied the effect of lectures on physics and some concerned subjects. First, the number of each student's attendance and the attitude while attending classes were inquired. Next, the concentration of each student's attention on the lecture was evaluated by classifying the attitude. The product of the percentage of attendance and the concentration corresponds to the total study hours in the class. The correlation of the product with the score on the examination was checked. This method is useful to improve lectures.
Tamotsu Ohno:
To topInfluence of preliminary knowledge and students’ attitude while attending classes on terminal examinations in physics and related subjects
Bulletin of the Liberal Arts and Science Course, Aichi Medical University No.22 (1995) pp.39-47 (in Japanese).