摘要
研究了10 keV Cl^-离子穿越Al2O3绝缘微孔膜的物理过程,发现穿越的Cl^-其分布中心在初束中心即0°附近,Cl^-离子穿透率下降与几何穿透一致,这是典型的直接几何穿越有一定角发散的微孔导致的结果;而出射的Cl0和Cl^+以微孔轴向为中心分布,Cl^+和Cl0穿透率下降慢于几何穿透.模拟计算发现沉积电荷会使出射粒子中Cl^-占主要成分,并使出射Cl^-角分布中心移动到微孔轴向方向而随微孔膜倾角移动;而在不考虑沉积电荷的情况下,计算结果较好地符合了实验结果.通过分析在不同倾角下散射过程对出射粒子的角分布和电荷态分布的影响,发现绝大部分的Cl0是通过一次和两次散射出射的,其中一次散射出射的Cl0占主要成分,从而导致出射的Cl0沿微孔轴向出射而Cl^+主要是经过一次碰撞出射.这导致了随倾角增大,出射的Cl0穿透率下降速度比Cl^+小,Cl0所占比例相对增大较快,从而导致观测到的Cl^+/Cl0的比例下降.本文结果更仔细地描述了低能离子穿越绝缘体微孔的物理机理,印证了之前实验和理论工作的结果,发现在10 keV以上能区的Cl^-离子穿越绝缘微孔膜的过程中,沉积电荷并未起到主要作用,其主要穿透特征是散射过程造成的.
The transmission of 10-keV Cl^-ions through Al2O3 insulating nanocapillaries is studied both by experiment and simulation.The double-peak structure in the transmitted angular distribution is found to be the same as our previous result.The peak around the direction of the primary beam is caused mainly by the directly transmitted Cl^-,and the other peak around the tilt angle of Al2O3 nanocapillaries is mainly induced by Cl^+and Cl0.The intensity of transmitted Cl^-decreases with the tilt angle increasing,which is in accord with the geometrically allowed transmission.Beyond the geometrically allowed angle,the transmitted projectiles are mainly Cl^+ions and Cl0 atoms.The ratio of transmitted Cl^+ion to Cl0 atom drops as tilt angle increases,and it turns more obvious when the tilt angle is larger than the limit of the geometrical transmission.A detailed physics process was developed within Geometry and Tracking 4(Geant4)to perform the trajectory simulation,in which the forces from the deposited charges and the image charges,the scattering from the surfaces as well as the charge exchange are taken into consideration.The transmissions at the tilt angle of1.6 o are simulated for the cases without and with deposited charges of-100 e/capillary.For the deposition charge quantity of-100 e/capillary,the majority of the transmitted projectiles are mainly the directly transmitted Cl^-ions exiting to the direction of tilt angle,and the transmitted Cl0 and Cl^+account for a very small portion.While for the case with no deposited charges,the simulation results agree well with the experimental results.The dependence of the scattering process on the tilt angle,which results in the different features in the transmitted projectiles,is studied in detail by the simulation.It is found that the transmitted Cl0 atoms exit through single to multiple scattering,and most of transmitted Cl0 atoms exit through single and double scattering,and are centered along the axis of nanocapillaries,while Cl^+ions mainly exit by single scattering,which re
作者
哈帅
张文铭
谢一鸣
李鹏飞
靳博
牛犇
魏龙
张琦
刘中林
马越
路迪
万城亮
崔莹
周鹏
张红强
陈熙萌
Ha Shuai;Zhang Wen-Ming;Xie Yi-Ming;Li Peng-Fei;Jin Bo;Niu Ben;Wei Long;Zhang Qi;Liu Zhong-Lin;Ma Yue;Lu Di;Wan Cheng-Liang;Cui Ying;Zhou Peng;Zhang Hong-Qiang;Chen Xi-Meng(School of Nuclear Science and Technology,Lanzhou University,Lanzhou 730000,China;School of Nuclear Engineering and Technology,North China Electric Power University,Beijing 102206,China;RIKEN Nishina Center,RIKEN,Wako 351-0198,Japan;Department of Physics,University of Gothenburg,SE-41296 Gothenburg,Sweden)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2020年第9期123-134,共12页
Acta Physica Sinica
基金
国家自然科学基金(批准号:U1732269,11475075)
瑞典科研与教育国际合作基金(STINT)(批准号:IB2018-8071)资助的课题.
