Electronic stopping power of swift heavy ions in carbon

The mean stopping power of He, Be, C and Al in carbon has been studied in a continuous energy ranging from 100 to 800 keV per nucleon using a modified time of flight-energy elastic recoil detection analysis set-up. In order to eliminate the calibration problems of Si detectors associated with heavy ions, the time of flight section was used to measure recoil energy both before entering and after passing through the stopping foil. Consequently, the energy dependence of the stopping power was achieved with high precision. The effect of the foil thickness on the mean stopping power was investigated by tilting the stopping foil at different angles to the incoming particles to increase the effective foil thickness up to 22%. The stopping curves obtained at different tilting angles show a similar energy dependence with scattering less than 0.8% from each other, and no obvious thickness dependence is observed. Both the stopping power and the energy dependence are in good agreement with the literature data. Comparing with semi-empirical SRIM prediction, considerable discrepancies up to 6%, 10% and 8% in stopping values for Be, C and Al, respectively, are observed.     

110keV56Fe^1^＋离子注入麦胚中的能量沉积分布

测量１１０ＫＥｖ５６Ｆｅ＾１＾＋离子注入麦胚中的射程为２５７．１ｎｍ。根据测得的＾５＾６Ｆｅ＾１＾＋离子相对浓度随深度的分布和注入离子的总面密度，求得了＾５＾６Ｆｅ＾１＾＋离子绝对浓度随深度的分布。采用ＴＲＩＭ８８程序计算得到了不同浓度上注入离子的阻止本领，从而求得了随深度的能量沉积分布。并讨论了细胞损伤的可能机理。     

一种新阈探测器的实验验证和重离子靶区中子测量

验证了用^2099Bi作为一种新的阈探测器测量高能中子的可能性，并利用^115In,^27Al,^19F,^12C和^209Bi组成的阈探测器组合测量了中能重离子反应实验靶区出射中子的注量率分布、能量分布和剂量当量率分布。     

Readout electronics of a prototype spectrometer for measuring low-energy ions in solar wind plasma

Readout electronics is developed for a prototype spectrometer for in situ measurement of low-energy ions of30 e V/e–20 ke V/e in the solar wind plasma.A low-noise preamplifier/discriminator(A111F) is employed for each channel to process the signal from micro-channel plate(MCP) detectors.A high-voltage(HV) supply solution based on a HV module and a HV optocoupler is adopted to generate a fast sweeping HV and a fixed HV.Due to limitation of telemetry bandwidth in space communication,an algorithm is implemented in an FPGA(field programmable gate array) to compress the raw data.Test results show that the electronics achieves a 1 MHz event rate and a large input dynamic range of 95 p C.A slew rate of 0.8 V/ls and an integral nonlinearity of 0.7-LSB for the sweeping HV,and a precision of less than 0.8 % for the fixed HV are obtained.A vacuum beam test shows an energy resolution of 12 ± 0.7 % full width at half maximum(FWHM) is achieved,and noise counts are less than10/sec,indicating that the performance meets the physical requirement.     

Determination of the electronic energy loss of light ions in a silicon lattice by using the transmission ion channeling method

Charged particle activation analysis (CPAA) is able to analyze light elements such as carbon and oxygen at trace levels in semiconductor materials. This technique requires the knowledge of the stopping powers of these materials for channeled ions. The electronic energy loss for ions entering the crystal lattice in a random direction is well established. The electronic energy losses for protons, deuterons, ³He⁺ and ⁴He⁺ ions entering a 3.6 μm thick silicon single crystal along the 1 0 0 direction were measured by using the transmission of particles technique. Data obtained were compared with those obtained by other authors using theoretical and experimental methods.