| Co-Investigator(Kenkyū-buntansha) |
MIZOBUCHI Akira Inst. for Nuclear Study, The Tokyo Univ, Professor, 原子核研究所, 教授 (40028121)
FUKUDA Mitsunori Dept. Phys, Osaka Univ, Research Associate, 理学部, 助手 (50218939)
MATSUTA Kensaku Dept. Phys, Osaka Univ, Research Associate, 理学部, 助手 (50181722)
NOJIRI Yoichi Dept. Phys, Osaka Univ, Associate Professor, 理学部, 助教授 (90028233)
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| Research Abstract |
Since the soft-pionic effect in the time-like component of the weak nucleon axial vector is dependent on the momentum transferred in the decay process, the effect are very much enhanced compared with that of the space components ; it reaches to about 40 % of the impulse value. Because of such huge enhancement, it is suitable as a probe for the investigation of the betaーDecay processes, chiral invariance, and the nature of the pion as boson. For such experimental works, the alignment correlation coefficients of mirror beta decays, and the 0^---0^+ transition rates have been the quantities to be measured. As those values were as small as the weak magnetism term, the first step of the measurements was to develop equipments in which the beta-ray detectors were free from the scattered beta rays, and to develop spin manipulating technique that was imperative to create spin alignments converted from largely polarized ensemble. Because of these technical improvements, it became possible to deduce precisely the weak magnetism form factor from the analyses of the energy spectra of ^<12>B and ^<12>N. Therefore, this term can also be used as a probe of the effective masses of the nucleons, which may be used for the studies of quark effects in nucleus.
One other important direction of the present project was to develop facilities for the production of the spin polarized betaーemitting nuclides for the present studies. A new acceleration techniques was developed for the unstable target fragments to get 100 keV/nucleon, i. e., an RFQ LINAC was connected with an ion source. To polarize the ions, beam-foil method was developed. Another equipment was fragment separator for the high-energy projectile fragments produced in high-energy heavy-ion reactions. In this case, it was discovered that the projectile was polarized in the reaction itself.
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