Developing Cloud Chambers with High School Students

The result and outcome of the \textit{cloud chamber project}, which aims to develop a cloud chamber useful for science education is reported in detail. A project includes both three high school students and a teacher as a part of Super Science High School (SSH) program in our school. We develop a dry-ice-free cloud chamber using salt and ice (or snow). Technical details of the chamber are described. We also argue how the project have affected student's cognition, motivation, academic skills and behavior. The research project has taken steps of professional researchers, i.e., in planning research, applying fund, writing a paper and giving a talk in conferences. From interviews with students, we have learnt that such style of scientific activity is very effective in promoting student's motivation for learning science.Comment: 9 pages, accepted to the proceedings of APPC12 - the 12th Asia Pacific Physics Conferenc

An improved method for determining the DC magnetization curve using a ring specimen

When the DC magnetization curve (B-H) of nonoriented material is measured in a ring specimen, there is an intrinsic error due to the assumption that the mean magnetic path length is equal to the mean geometric path length. A novel method for determining the B-H curve accurately is proposed. The validity of the method is verified by experiments</p

Spectroscopy of Candidate Members of the Eta Cha and MBM12 Young Associations

We present an analysis of candidate members of the Eta Cha and MBM 12A young associations. For an area of 0.7 deg^2 toward Eta Cha, we have performed a search for members of the association by combining JHK_s photometry from 2MASS and i photometry from DENIS with followup optical spectroscopy at Magellan Observatory. We report the discovery of three new members with spectral types of M5.25-M5.75, corresponding to masses of 0.13-0.08 M_sun by theoretical evolutionary models. Two and three of these members were found independently by Lyo and coworkers and Song and coworkers, respectively. Meanwhile, no brown dwarfs were detected in Eta Cha down to the completeness limit of 0.015 M_sun. For MBM 12A, we have obtained spectra of three of the remaining candidate members that lacked spectroscopy at the end of the survey by Luhman, all of which are found to be field M dwarfs. Ogura and coworkers have recently presented four "probable" members of MBM 12A. However, two of these objects were previously classified as field dwarfs by the spectroscopy of Luhman. In this work, we find that the other two objects are field dwarfs as well.Comment: to be published in The Astrophysical Journal, 19 pages, 7 figure

Strong Coupling Limit of Bethe Ansatz Solutions in Massive Thirring Model

We study the strong coupling limit of the Bethe ansatz solutions in the massive Thirring model. We find analytical expressions for the energy eigenvalues for the vacuum state as well as n-particle n- hole states. This formula is compared with the numerical results and is found to achieve a very good agreement. Also, it is found that the 2-particle 2- hole and higher particle-hole states describe n- free bosons states in this limit. The behaviors of the strong coupling limit of the boson mass for various model calculations are examined. We discuss an ambiguity of the coupling constant normalization due to the current regularization.Comment: 15 pages, to appear in Ann. Phys. 281 (2000), Ma