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Giant Mesonic Effects in the Time Component of Weak Nucleon Axial Vector, and Chiral Invariance

弱核子轴向矢量时间分量的巨介子效应和手性不变性

基本信息

批准号：
63420006
负责人：
MINAMISONO Tadanori
金额：
$ 21.95万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1990
项目状态：
已结题

项目摘要

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.

由于弱核子轴向矢量类时分量中的软介子效应依赖于衰变过程中传递的动量，因此与空间分量相比，软介子效应大大增强，约为冲量值的40%。由于这种巨大的增强，它适合作为研究β衰变过程，手征不变性和π介子作为玻色子的性质的探针。对于这样的实验工作，镜像β衰变的取向相关系数和0^-0 ^+跃迁速率是需要测量的量。由于这些值与弱磁性项一样小，测量的第一步是开发β射线探测器不受散射β射线影响的设备，并开发自旋操纵技术，这对于从大部分极化系综转换成自旋排列至关重要。由于这些技术上的改进，从^ B和^ N的能谱分析中精确地推导出弱磁性形状因子成为可能<12><12>。因此，该项也可作为核子有效质量的探针，用于研究核中的夸克效应。本项目的另一个重要方向是发展生产自旋极化β介子发射核素的装置。发展了一种新的加速技术，使不稳定靶碎片达到100 keV/核子，即：例如，将一个超导直线加速器与一个离子源连接。为了消除离子，发展了束箔法。另一个设备是碎片分离器，用于分离高能重离子反应中产生的高能射弹碎片。在这种情况下，发现射弹在反应本身中被极化。