扫描质子微探针质子束刻写

质子束刻写技术利用MeV能量的聚焦质子束对抗蚀剂材料直接刻写m甚至nm尺度微结构。研究了质子束刻写中抗蚀剂胶层样品厚度与涂层机旋转速度的关系以及曝光对抗蚀剂的影响,解决了质子束刻写中抗蚀剂厚胶层样品的制备、固化、显影等技术问题,利用扫描质子微探针系统,在正型抗蚀剂胶层上刻写出m尺度的海宝图形、 双矩形结构,在负型抗蚀剂上刻写出m尺度的平行线条、十字形微结构。     

离子微束技术及其多学科应用

通过微米孔准直或电磁聚焦技术可将加速器产生的MeV离子束形成微米尺寸的离子束斑(微束), 从而用来研究固体和生物样品的微米空间分辨的材料信息和辐照响应。 结合MeV离子微束的发展历史综述了微束技术和跨学科应用, 包括利用微束开展具有空间分辨的离子束分析、 单粒子效应、 微纳加工和细胞辐射响应等研究。 介绍了中国科学院近代物理研究所的高能重离子微束辐照装置, 该装置成功地将总能量为1 GeV的C离子在大气中聚焦为1 μm×2 μm的微米束斑。 Beam of MeV ions from particle accelerators can be confined by collimators or focused by electrical/magnetic quadruples into micrometer size, and this microbeam can be used to obtain spatial information or radiation effect in solids and biological samples. This paper reviews the technical developments and the multi disciplinary applications of microbeam, including ion beam analysis, single event effect in semiconductor devices, proton beam writing and cellular response to targeted particle irradiations. Finally, the high energy heavy ion microbeam facility at the Institute of Modern Physics of Chinese Academy of Sciences is introduced, which has successfully focused 1 GeV Carbon ions into a beam spot of 1 μm×2 μm in air.     

多功能扫描质子核探针信号探测和数据获取系统

为了在一次扫描质子核探针实验中能获取多种物理信息,研制了多功能信号探测与数据获取系统。系统由组合探测器、多站多参量数据采集与束流扫描、样品台控制与显微观测三个子系统组成。组合探测器包括了Si(Li)X射线探测器,高纯Geγ射线探测器,以及Au(Si)面垒带电粒子探测器,可完成多种物理参数的同时获取。系统的核心数据采集与束流扫描系统基于NI公司的PXI-7852R数据采集卡和LabVIEW软件平台,具备了多个物理信号采集、多能谱显示以及束流扫描和二维成像等功能。六轴高精度真空样品台由计算机控制,可实现显微图像对样品的定位及对扫描区域的可视化选择。初步实验验证了该系统的可靠性与稳定性。     

核探针技术及其应用

核探针的概念起源于电子探针,它综合了离子束分析技术的特点,已成为很有应用前景的分析工具.本文结合上海新建成的核探针,介绍它们的原理、结构和部分应用. In concept,the scanning nuclear microprobe is similar to the scanning electron micro-probe,but has much higher sensitivity for microanalysis.The main features and the construction of thenew-built Nuclear Microprobe in Shanghai are described.It has been proved to be an ideal tool for mi-croanalysis in the fields of medical and biology,metallurg,microelectronics,archaeology and earthsciences.Its potentiality is demonstrated with examples in the applications of these fields.     

基于同步辐射的快速扫描X射线微束荧光成像方法

在上海光源硬X射线微聚焦光束线站(BL15U1)上, 基于EPICS软件平台, 集成运动控制, 光强探测, 荧光探测等功能, 实现了"飞行"模式 (on-the-fly) X射线扫描微束荧光成像方法. 用"飞行"扫描X射线荧光成像法获得了标准镍网, 以及微量元素Cu, Zn,K, Fe在样品老鼠脾内的分布图像, 结果显示该方法不但在速度上有了极大的提高, 而且获得的元素分布图像具有高质量. 关键词： 快速扫描X射线微束荧光成像 同步辐射 微量元素分布     

强流质子束辐照形成的冲击波

 对强流质子束在铝材料中引起的冲击波进行了数值模拟，其中强流质子束在铝中的能量沉积行为采用蒙特卡罗方法模拟，而能量的非均匀沉积后引起的力学效应采用一维流体弹塑性模型进行计算。计算给出了强流质子束在铝材料中的能量沉积曲线和引起的冲击波的时间演化规律。     

激光加速质子束空间电荷力研究

激光加速器可以输出具有独特品质的质子束,例如μm尺寸、ps脉冲长度和高峰值电流。强流粒子束的空间电荷力效应较强,对面向应用的束流传输提出了挑战。通过二维PIC模拟研究了激光加速后与质子速度接近的电子的影响。采用椭球模型估算空间电荷力的影响,比较不同电荷分布的差异。结果表明每束团质子数超过1010后空间电荷力显著影响质子束传输,甚至严重破坏束流品质。空间电荷力的影响在20 ps后显著减弱,离开靶约1.2 mm。     

毛细管准直微束过程模拟与微束品质分析

利用GEANT4程序对复旦大学单粒子微束的毛细管准直过程进行了蒙特卡罗模拟。计算结果表明:当前采用的1 m孔径、1 mm长度的毛细玻璃管准直器能够引出峰值能量2.2 MeV、能量分辨130 keV、束径2.4 m的质子微束,可达到装置对微束能量与束径分辨的设计指标,从理论上明确了毛细管准直微束引出的可行性。针对影响入射目标细胞微束品质的主要因素,分析了微束品质与准直系统和入射束流各状态参数的依赖关系,为毛细管准直微束的引出与优化提供了必要的理论依据。     

毛细管准直微束过程模拟与微束品质分析

利用GEANT4程序对复旦大学单粒子微束的毛细管准直过程进行了蒙特卡罗模拟。计算结果表明：当前采用的1 m孔径、1 mm长度的毛细玻璃管准直器能够引出峰值能量2.2 MeV、能量分辨130 keV、束径2.4 m的质子微束,可达到装置对微束能量与束径分辨的设计指标,从理论上明确了毛细管准直微束引出的可行性。针对影响入射目标细胞微束品质的主要因素,分析了微束品质与准直系统和入射束流各状态参数的依赖关系,为毛细管准直微束的引出与优化提供了必要的理论依据。     

散裂靶中质子束窗的散射效应

质子束窗是在高功率靶区中的一个分界窗,它将质子输运线上高真空区域和氦容器中的氦环境分开。在其他散裂中子源中质子束窗的热效应以及机械问题都已经被研究过了,但质子束在该窗中散射效应的研究却很少被报导,然而在靶设计中如果没有处理好质子束窗的散射效应会有很大的问题。报导了质子束窗散射效应的模拟计算结果,包括不同质子束窗的材料和结构选择,并以中国散裂中子源（CSNS）为例,介绍了在CSNS一期和二期中质子束窗采用周边水冷的铝合金单层结构,CSNS三期采用中间水冷的铝合金夹层结构。文中给出了不同结构的质子束窗和不同的与靶距离散射效应对靶上经非线性磁铁均匀化的束流分布的影响的模拟计算结果。模拟结果显示质子窗的散射效应对束流损失和靶上的束流分布有重要的影响。     

扫描透射离子显微成像系统的建立和实验研究

基于上海应用物理研究所的扫描质子微探针系统,对扫描透射离子显微成像（STIM）技术进行了仿真分析和实验研究,建立了基于中值滤波方法的数据处理程序,获得了大鼠股骨切片的面密度分布和薄壁小球的离轴STIM图像。理论分析和实验结果显示：由在轴探测数据的中值滤波结果可以计算出定量的面密度分布信息,由能量窗滤波的离轴探测数据则可以给出高分辨的定性图像,这在薄样品、强束流、以及质子激发X荧光（PIXE）分析同时进行的STIM分析中尤为有用;增加获取的事件数、选择合适的滤波方法可以使测量误差远小于阻止本领计算带来的误差。该方法可以用于测量几十μm尺度样品的绝对质量以及辅助PIXE技术进行元素定量分布分析。     

扫描透射离子显微成像系统的建立和实验研究

 基于上海应用物理研究所的扫描质子微探针系统,对扫描透射离子显微成像（STIM）技术进行了仿真分析和实验研究,建立了基于中值滤波方法的数据处理程序,获得了大鼠股骨切片的面密度分布和薄壁小球的离轴STIM图像。理论分析和实验结果显示：由在轴探测数据的中值滤波结果可以计算出定量的面密度分布信息,由能量窗滤波的离轴探测数据则可以给出高分辨的定性图像,这在薄样品、强束流、以及质子激发X荧光（PIXE）分析同时进行的STIM分析中尤为有用;增加获取的事件数、选择合适的滤波方法可以使测量误差远小于阻止本领计算带来的误差。该方法可以用于测量几十μm尺度样品的绝对质量以及辅助PIXE技术进行元素定量分布分析。     

C-ADS中质子束窗散射效应和热力学计算

质子束窗是C-ADS中隔离加速器的真空环境与靶的非真空环境的重要部件。质子束窗材料及其冷却介质造成的束流散射效应是造成束流在靶外损失的主要因素,由于质子束窗中的高能量沉积和高辐照效应,束窗的热力学计算显得尤为重要。计算结果表明：当质子束窗和散裂靶距离为1.5 m时,通过选取合理的结构参数,多管道型质子束窗结构可以将靶外束流损失控制在1%以内。束窗中总的应力,包括由于温度升高造成的热应力、冷却剂的静压,以及束窗两侧加速器真空与外部非真空环境的压强差造成的应力,可以有效控制在所用材料的许用应力之内。并通过计算讨论给出C-ADS中质子束窗的初步设计参数。     

Proton beam scanning modular unit for a nuclear microprobe

General ideas underlying the design of a proton beam scanning modular unit intended for a nuclear microprobe consisting of a ferromagnetic x-y scanning system and a dynamic power supply are described. For an H⁺ ion energy of 14 MeV, the unit provides a rectangular scanning raster with a linear size of ±300 μm on the target and a minimal point-to-point switch time of 200 μs. The positioning time does not exceed 40 μs.     

Differential phase contrast with a segmented detector in a scanning X‐ray microprobe

Scanning X‐ray microprobes are unique tools for the nanoscale investigation of specimens from the life, environmental, materials and other fields of sciences. Typically they utilize absorption and fluorescence as contrast mechanisms. Phase contrast is a complementary technique that can provide strong contrast with reduced radiation dose for weakly absorbing structures in the multi‐keV range. In this paper the development of a segmented charge‐integrating silicon detector which provides simultaneous absorption and differential phase contrast is reported. The detector can be used together with a fluorescence detector for the simultaneous acquisition of transmission and fluorescence data. It can be used over a wide range of photon energies, photon rates and exposure times at third‐generation synchrotron radiation sources, and is currently operating at two beamlines at the Advanced Photon Source. Images obtained at around 2 keV and 10 keV demonstrate the superiority of phase contrast over absorption for specimens composed of light elements.     

Characterizing a proton beam with two different methods in beam halo experiments

In beam halo experiments, it is very important to correctly characterize the RFQ output proton beam. In order to simulate the beam dynamics properly, we must first know the correct initial beam parameters. We have used two different methods, quadrupole scans and multi-wire scanners to determine the transverse phase-space properties of the proton beam. The experimental data were analyzed by fitting to the 3-D nonlinear simulation code IMPACT. For the quadrupole scan method, we found that the RMS beam radius and the measured beam-core profiles agreed very well with the simulations. For the multi-wire scanner method, we choose the case of a matched beam. By fitting the IMPACT simulation results to the measured data, we obtained the Courant-Snyder parameters and the emittance of the beam. The difference between the two methods is about eight percent, which is acceptable in our experiments.     

Characterizing a proton beam with two different methods in beam halo experiments

In beam halo experiments, it is very important to correctly characterize the RFQ output proton beam. In order to simulate the beam dynamics properly, we must first know the correct initial beam parameters. We have used two different methods, quadrupole scans and multi-wire scanners to determine the transverse phase-space properties of the proton beam. The experimental data were analyzed by fitting to the 3-D nonlinear simulation code IMPACT. For the quadrupole scan method, we found that the RMS beam radius and the measured beam-core profiles agreed very well with the simulations. For the multi-wire scanner method, we choose the case of a matched beam. By fitting the IMPACT simulation results to the measured data, we obtained the Courant-Snyder parameters and the emittance of the beam. The difference between the two methods is about eight percent, which is acceptable in our experiments.     

Direct writing of microtunnels using proton beam micromachining

The production of high aspect ratio microstructures is a potential growth area. The combination of deep X-ray lithography with electroforming and micromolding (i.e. LIGA) is one of the main techniques used to produce 3D microstructures. The new technique of proton micromachining employs focused MeV protons in a direct write process which is complementary to LIGA. During ion exposure of positive photoresist like PMMA, scission of molecular chains occurs. These degraded polymer chains are removed by the developer. The aim of this paper is to investigate the capabilities of proton micromachining as a lithographic technique. We show the realization of sub-surface channels, or microtunnels, which have been fabricated in only one exposure and without cutting or resurfacing the material. Using our Van-de-Graaff accelerator, the resist (PMMA) has been exposed with high-energy protons (2.5 MeV). The range of charged particles in matter is well-defined and depends on the energy. Therefore, it is possible to obtain a dose which is sufficient to develop the bottom part of the ion paths but not the top part. Thus, by selecting the energy and the exposure time, a big variety of microtunnels can be realized.