中子超镜的优化设计  

Optimized Design of Neutron Supermirror

作　　者：张众[1] 王占山[1] 吴永荣[1] 陈玲燕[1] 

机构地区：[1]同济大学物理系精密光学工程技术研究所,上海200092

出　　处：《原子能科学技术》2010年第1期84-88,共5页Atomic Energy Science and Technology

基　　金：国家自然科学基金资助项目(10675091);上海市科学技术委员会资助项目(07DZ22302);同济大学青年优秀人才培养行动计划资助项目

摘　　要：中子超镜的主要光学性能指标是反射临界角,反射临界角通常由镍块体材料的全反射临界角的倍数m来表征。本文采用增加帽层、优化关键参数和引入新设计参数的方法,弥补了中子超镜算法在m≤1区域内的局限性,实现了包含较少膜对数K的大m值中子超镜结构设计。利用Nevot-Croce模型模拟了多层膜的非理想界面,讨论了多层膜表界面粗糙度对超镜反射特性的影响。结果表明,对m=3的Ni/Ti中子超镜仅需200个膜对,在制作工艺上,要求制备m=3的Ni/Ti超镜的膜层界面粗糙度应小于1.5 nm,以保证其反射率不低于80%。An important property of a supermirror is its critical angle,which is measured in multiples m of the critical angle of bulk nickel by convention.Adding Ni capping layer on the outmost of supermirrors,optimizing its key parameter ξ0 and introducing a novel parameter to design neutron supermirrors can offset the reflectivity limitation in m≤1 region.The designed Ni/Ti neutron supermirror has less bi-layer pairs（K=200） and large m value（m=3）,which would be easier to fabricate.The effects of the surface and interfacial roughness on neutron supermirrors were discussed by using Nevot-Croce model to simulate the non-ideal interface of the supermirror.The calculation result shows that 1.5 nm interfacial roughness should be required to make m=3 neutron supermirror with 200 bi-layer pairs and more than 80% critical reflectivity.

关 键 词：中子超镜 多层膜 全反射临界角 粗糙度 

分 类 号：O571.5[理学—粒子物理与原子核物理]