Construction of a polarized positron generator at low energy

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Positrons emitted from beta-decay is longitudinally polarized and have a helicity of v / c where v and c are the velocity of the positron and light respectively. Furthermore if one utilizes a radio-isotope, one can hardly obtain positron beams with definite energy and sufficient intesitiy.What we have achieved in this project is :1. We developed the new method to produced polarized positrons by means of the nuclear reaction ^<27>Al (p, n) ^<27> Si where incident protons of 18 Me Vare produced by a compact cycrotron.2. We established the reliable method to measure positron polarizations by utilizing the Zeeman effect.3. We completed the Monte Carlo simulator which can describe positron depolarizations in electric and magnetic fields as well as in materials. These achivements have been lectured in the international conferences and symposiums.On the basis of knowledges obtained in this research, we could construct the unique facility to provide high quality polarized positron beams i. e. TOPPS (TOkyo metropolitan university Polarized Positron beam System) which will enable us to perform various experimental studies concerning elementary particle physics, solid states physics and biological physics.