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Study of a Polarized Positron Source for Linear Colliders

直线对撞机偏振正电子源的研究

基本信息

批准号：
10640294
负责人：
OMORI Tsunehiko
金额：
$ 2.11万
依托单位：
High Energy Acclerator Research Organization
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

Studies were done at the Accelerator Test Facility (ATF) in KEK.As the first step, we performed the experiment to generate positrons via pair-creation from Compton scattered gamma-rays. In the experiment, we aimed to confirm that number of positron generated by our apparatus agreed to the design value. The 1.28 GeV electron beam extracted from the ATF collided with the laser beam of 2nd harmonic of the Nd : YAG laser. The energy of a laser photon is 2.33 eV.This collision generated gamma-rays which maximum energy was 56 MeV.The gamma-rays were injected to the 1-mm-thick tungsten target to generate positrons. The number of generated positrons was about 250 at just downstream of the target. This value agreed the design value within the expected error. The results of the experiment was published in "Nuclear Instruments and Methods in Physics Research". We did not measure the polarization of the positrons in this experiment.From the experience of the first step, we recognized that the existence of the background particles from the ATF accelerator was the serious obstruction against the polarization measurement. Therefore, as the second step, we performed following three developments.1. Development of the detector which has no sensitivity to low energy particles (most of background particles have low energy), but has high sensitivity to positrons generated by Compton scattered gamma-rays.2. Development of the detailed simulation code for polarization measurement.3. Construction of shields around the beam pipe to reduce the background particles.Through R/Ds of above three subjects we did accumulate large amount of data and experiences which are necessary to achieve the Polarization measurement. We believe those are of great use when we will perform further investigation to realize the polarize the polarized positron source.

在KEK的加速器试验设备（ATF）上进行了研究。作为第一步，我们进行了从康普顿散射γ射线中通过对产生产生正电子的实验。在实验中，我们的目的是确认我们的装置产生的正电子数符合设计值。从ATF引出的1.28GeV电子束与Nd：YAG激光器的二次谐波激光束碰撞。激光光子的能量为2.33eV。该碰撞产生最大能量为56MeV的伽马射线。将伽马射线注入1mm厚的钨靶以产生正电子。在靶的下游产生的正电子数量约为250个。该值在预期误差范围内与设计值一致。实验结果发表在《物理学研究中的核仪器和方法》上。本实验没有测量正电子的极化，从第一步的实验经验来看，ATF加速器背景粒子的存在是极化测量的严重障碍。因此，作为第二步，我们进行了以下三个开发。1.研制了对低能粒子（大多数背景粒子的能量都很低）不灵敏，而对康普顿散射γ射线产生的正电子灵敏度很高的探测器。详细的偏振测量仿真程序的开发.通过以上三个课题的研究和开发，我们积累了大量的数据和经验，这是实现偏振测量所必需的。我们相信，这对进一步研究极化正电子源的实现有很大的帮助。