Construction of a polarized positron generator at low energy

从β衰变发射的正电子是纵向极化的，螺旋度为v / c，其中v和c分别是正电子和光的速度。此外，如果利用放射性同位素，很难得到具有确定能量和足够强度的正电子束。我们在这个项目中取得的成果是：1。我们开发了一种产生极化正电子的新方法，即通过紧凑回旋加速器产生入射质子为18 Me v1的核反应^<27>Al (p, n) ^<27> Si。我们利用塞曼效应建立了测量正电子极化的可靠方法。我们完成了蒙特卡罗模拟器，该模拟器可以描述电场和磁场以及材料中的正电子去极化。这些成果已在国际会议和专题讨论会上发表。基于本研究所获得的知识，我们可以建立一个独特的设施，提供高质量的极化正电子束，即TOPPS（东京城市大学极化正电子束系统），这将使我们能够进行基本粒子物理，固体物理和生物物理的各种实验研究。

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.