日本理化所电子与放射性核素散射装置  

Electron scattering facility for short-lived nuclei at RIKEN

作　　者：王硕[1] 

机构地区：[1]山东大学(威海)空间科学与物理学院山东省光学天文与日地空间环境重点实验室,威海264209

出　　处：《核技术》2014年第10期119-123,共5页Nuclear Techniques

基　　金：山东大学青年培养项目(No.2014ZQXM021)资助

摘　　要：为了精确测量放射性核素原子核的内部结构,日本理化学研究所研制出一种新颖的制作放射性核素靶的方法,使电子与放射性核素散射实验成为可能。该方法主要利用电子储存环中的"离子束缚"现象,使得从外部离子源注入的放射性核素离子被束缚在电子存储环中,形成放射性核素靶并进而与电子束发生散射。电子与放射性核素散射装置于2009年在日本理化学研究所开始建造,其主要包括三个部分:(1)电子束产生装置;(2)电子存储环;(3)放射性核素生成与分离装置。目前除放射性核素生成装置仍然在建设中,其余部分已于2010年建造完成,并利用稳定原子核133Cs和132Xe对其性能进行了测试。结果表明,当电子束流强度约为200 mA时,散射实验的亮度可达约1027 cm-2·s-1。Background： It has already been confirmed that the SCRIT （Self-Confining Radioactive Isotope Ion Target） method can be used for electron scattering experiment for short-lived nuclei. An electron scattering facility consisting of a microtron type electron accelerator （RTM： Racetrack Mierotron）, an electron storage ring （SR2： SCRIT-equipped RIKEN Storage Ring） and an ISOL （Isotope Separator Online） involving an RI generator, had already been constructed in 2010 at RIKEN Nishina Center to realize electron scattering experiments for short-lived nuclei with SCRIT technique. Purpose： Ions of stable nuclei, ^133Cs and ^132Xe, were used as targets to evaluate the performance of this facility. Methods： In the testing experiment, the energy of electron beam was set to 150 MeV. The stored electron beam current was -200 mA with lifetime -200 min. To determine the achievable luminosity, elastically scattered electrons were measured by a detection system, which consists of a drift chamber, plastic scintillation detectors and two calorimeters. The trajectories and energies of scattered electrons were determined by the drift chamber and two calorimeters. The detector system covers the scattering angle from 25° to 50°. Results： From the vertex distribution and energy loss in the calorimeters of scattered electrons, the number of elastic scattered electrons from target ions was obtained and the luminosity was determined to be nearly 1027 cm^2·s^-1 at beam current 200 mA, which is the required luminosity to determine the charge density distribution of the target nucleus. Conclusion： Except for the RI beam generator, the other parts of SCR1T electron scattering facility have been already constructed. The first experiment for this facility will be elastic electron scattering for short-lived Sn isotopes including a doubly magic nucleus ^132Sn in 2015.

关 键 词：放射性核素 电子散射 电子储存环 离子束缚 

分 类 号：TL99[核科学技术—核技术及应用]