Investigation of radiological properties of some shielding materials on charged and uncharged radiation interaction for neutron generator

Radiation interaction parameters such as total stopping power, projected range (longitudinal and lateral) straggling, mass attenuation coefficient, effective atomic number (Z_eff) and electron density (N_eff) of some shielding materials were investigated for photon and heavy charged particle interactions. The ranges, stragglings and mass attenuation coefficients were calculated for the high-density polyethylene(HDPE), borated polyethylene (BPE), brick (common silica), concrete (regular), wood, water, stainless steel (304), aluminum (alloy 6061-O), lead and bismuth using SRIM Monte Carlo software and WinXCom program. In addition, effective atomic numbers (Z_eff) and electron densities (N_eff) of HDPE, BPE, brick (common silica), concrete (regular), wood, water, stainless steel (304) and aluminum (alloy 6061-O) were calculated in the energy region 10?keV–100?MeV using mass stopping powers and mass attenuation coefficients. Two different methods namely direct and interpolation procedures were used to calculate Z_eff for comparison and significant differences were determined between the methods. Variations of the ranges, longitudinal and lateral stragglings of water, concrete and stainless steel (304) were compared with each other in the continuous kinetic energy region and discussed with respect to their Z_effs. Moreover, energy absorption buildup factors (EABF) and exposure buildup factors (EBF) of the materials were determined for gamma rays as well and were compared with each other for different photon energies and different mfps in the photon energy region 0.015–15?MeV.     

聚合物物理属性对离子注入效应的影响

聚合物导电性能差, 表面电荷积聚所产生的电容效应致使其表面电位衰减, 采用等离子体浸没离子注入对其表面改性是非常困难的. 建立了绝缘材料等离子体浸没离子注入过程的粒子模拟(PIC)模型, 实时跟踪离子在等离子体鞘层中的运动形态及特性并进行统计分析. 并基于PIC模型, 将聚合物表面的二次电子发射系数直接与离子注入即时能量建立关联, 研究了聚合物厚度、介电常数和二次电子发射系数等物理量对鞘层演化、离子注入能量和剂量的影响规律. 研究结果表明: 当聚合物厚度小于200 μ m, 相对介电常数大于7, 二次电子发射系数小于0.5时, 离子注入剂量和高能离子所占的份额与导体离子注入情况相当. 通过对聚合物表面离子注入剂量和高能离子所占份额的研究, 为绝缘材料和半导体材料表面等离子体浸没离子注入的实现提供了理论和实验依据.     

等离子体浸没离子注入非导电聚合物的适应性及栅网诱导效应的研究

本文建立了绝缘材料等离子体浸没离子注入过程的动力学Particle-in-cell(PIC)模型, 将二次电子发射系数直接与离子注入即时能量建立关联, 研究了非导电聚合物厚度、介电常数和二次电子发射系数对表面偏压电位的影响规律以及栅网诱导效应. 研究结果表明: 非导电聚合物较厚时, 表面自偏压难以实现全方位离子注入, 栅网诱导可以间接为非导电聚合物提供偏压, 并抑制二次电子发射, 为厚大非导电聚合物表面等离子体浸没离子注入提供了有效途径.     

Plasma immersion ion implantation for silicon processing

Plasma Immersion Ion Implantation (PIII) is a technology which is currently widely investigated as an alternative to conventional beam line implantation for ultrashallow doping beyond the 0.15 μm technology. However, there are several other application areas in modern semiconductor processing. In this paper a detailed discussion of the PIII process for semiconductors and of actual as well as future applications is given. Besides the well known advantages of PIII — fast process, implantation of the whole surface, low cost of ownership — several peculiarities — like spread of the implantation energy due to finite rise time or collisions, no mass separation, high secondary electron emission — must be mentioned. However, they can be overcome by adjusting the system and the process parameters. Considering the applications, ultrashallow junction formation by PIII is an established industrial process, whereas SIMOX and Smart‐Cut by oxygen and hydrogen implantation are current topics between research and introduction into industry. Further applications of PIII, of which some already are research topics and some are only investigated by conventional ion implantation, include seeding for metal deposition, gettering of metal impurities, etch stop layers and helium implantation for localized lifetime control.     

Surface modification of hard alloy by Y ion implantation under different atmosphere

To enhance the properties of hard alloy, rare-earth metal yttrium (Y) was implanted into its surface by using Metal Vapor Vacuum Arc (MEVVA) source implantor. The experiments were finished under different vacuum conditions with/without aerating nitrogen in the chamber. The metallograph and phase formation of sample were characterized and analyzed with metallurgical microscope and X-ray diffraction. The results show that there exist new phases of C, YC₂, Y₂O₃, and WN in the sample surface. Moreover, it can be found that the performances of sample surface (such as microhardness, friction coefficient and corrosion resistance) are evidently improved, and that nitrogen atmosphere plays a very important role in farther promoting these performances. The surface modification of hard alloy is not only affected by the implantation itself, but also related to the microstructure transformation, which can be partly induced by the atmosphere.     

Radiation Parameters of Some Potential Bioactive Compounds

In this study,we aimed to determine the radiation parameters of some potential bioactive compounds.1-Aryl-3-dibenzylamino-propane-1-on hydrochloride type Mannich bases were synthesized via classical conventional heating method.Aryl part was changed as phenyl(C6H5),4-methylphenyl(4-CH3C6H4),4-fluorophenyl(4-FC6H4),4-nitrophenyl(4-NO2C6H4),4-chlorophenyl(4-ClC6H4),4-bromophenyl(4-BrC6H4),and 2-thienyl(C4H3S-2-yl).Mass attenuation coefficient(μm),effective atomic number(Zeff)and effective electron density(Nel)of compounds were determined experimentally and theoretically for at 8.040,8.910,13.40,14.96,17.48,19.61,22.16,24.94,32.19,36.38,44.48,50.38and 59.54keV photon energies by using an HPGe detector with a resolution of 182eV at 5.9keV.Radiation parameters of these compounds which can be anti-cancer drug candidate were given in the tables.The results show that phenyl ring behave like thiophene ring in terms of radiation absorption.It is thought that the results of study may drive allow the development of drug candidate new compounds in medical oncology.     

离子注入掺杂锐钛矿TiO2薄膜的光学性能

 在玻璃基体上,采用射频磁控溅射方法在不同的基体温度下制备了TiO₂薄膜,然后在薄膜中注入注量分别为5×1016, 1×1017和5×1017/cm2的N离子以制备N掺杂的TiO₂薄膜。X射线衍射结果表明：制备出的TiO₂薄膜为锐钛矿型。X射线光电子能谱研究结果表明：注入的N离子与TiO₂晶粒相互作用,形成了含氮的TiO_xN_2-x化合物,从而改变了TiO₂薄膜的吸收边;随N离子注量增加,吸收边移动更明显;同时,由于氮离子注入产生的辐照缺陷使TiO₂薄膜在紫外和可见光区的吸收也明显增强。     

等离子体源离子注入过程中半圆形碗状样品的两维温度分布

等离子体源离子注入过程(PSII)中样品温度是一个非常重要的参量。由于注入到样品上的能量很大，导致样品温度很高，所以在实验中获知样品的温度分布有着很重要的意义。本文利用热传导方程建立了半圆形碗状样品内部温度升高模型，研究样品内温度演化过程。以注入离子束流作为能量输入项，热辐射为能量损失项，并考虑了热辐射过程中样品的形状因子的影响。考察了离子注入过程中样品上所施加负偏压的脉冲宽度和频率对样品温度分布的影响。研究结果显示，脉冲频率达到一定值后，样品温度不再随频率增加而升高。     

Structure and micro-mechanical properties of helium-implanted layer on Ti by plasma-based ion implantation

The present paper concentrates on structure and micro-mechanical properties of the helium-implanted layer on titanium treated by plasma-based ion implantation with a pulsed voltage of −30 kV and doses of 3, 6, 9 and 12 × 10¹⁷ ions/cm², respectively. X-ray photoelectron spectroscopy and transmission electron microscopy are employed to characterize the structure of the implanted layer. The hardnesses at different depths of the layer were measured by nano-indentation. We found that helium ion implantation into titanium leads to the formation of bubbles with a diameter from a few to more than 10 nm and the bubble size increases with the increase of dose. The primary existing form of Ti is amorphous in the implanted layer. Helium implantation also enhances the ingress of O, C and N and stimulates the formations of TiO₂, Ti₂O₃, TiO, TiC and TiN in the near surface layer. And the amount of the ingressed oxygen is obviously higher than those of nitrogen and carbon due to its higher activity. At the near surface layer, the hardnesses of all implanted samples increases remarkably comparing with untreated one and the maximum hardness has an increase by a factor of up to 3.7. For the samples implanted with higher doses of 6, 9 and 12 × 10¹⁷ He/cm², the local displacement bursts are clearly found in the load-displacement curves. For the samples implanted with a lower dose of 3 × 10¹⁷ He/cm², there is no obvious displacement burst found. Furthermore, the burst width increases with the increase of the dose.     

Effect of ion implantation on the refractive index of glass

Studies on the changes of the index of refraction in glass due to ion implantation provide an insight into the structure of amorphous substances, besides being important for the development of techniques for the production of optical integrated circuits. Using a heavy ion accelerator, optically flat samples of Pyrex and Corning borosilicate glass were implanted with ions of gallium and argon at various incident energies and doses. The refractive index was then measured and found to be between 1.5 and 1.8 at a wavelength of 5893 A.U. The change in the refractive index was found to vary linearly with the incident dose irrespective of the ion species. This suggests that bombardment damage is mainly responsible for the effect. The dependence of the refractive index change on the incident dose however depends strongly on the chemical composition of the substrate glass.     

Production of highly charged argon ions from a room temperature electron beam ion trap

In this work, highly charged ions have been extracted from the advanced Electron Beam Ion Source (EBIS-A) developed in a scientific cooperation between the Dresden University of Technology and the DREEBIT GmbH Dresden. The charge state distributions of ions extracted from the EBIS-A are measured in the pulse and leaky modes under different operation conditions. Ar¹⁶⁺ ions with current of 2 pA are produced and extracted in the leaky mode. 3×10⁵ Ar¹⁸⁺ ions per pulse are extracted in the pulse mode. The ion charge state distribution is a     

Influence of ion implantation on titanium surfaces for medical applications

The implantation of ions into the near surface layer is a new approach to improve the osseointegration of metallic biomaterials like titanium. Meanwhile it is well known that surface topography and surface physico-chemistry as well as visco-elastic properties influence the cell response after implantation of implants into the human body. To optimize the cell response of titanium, ion implantation techniques have been used to integrate calcium and phosphorus, both elements present in the inorganic bone phase. In this context, the concentration profile of the detected elements and their chemical state have been investigated using X-ray photoelectron spectroscopy and Auger electron spectroscopy depth profiling. Ion implantation leads to strong changes of the chemical composition of the near surface region, which are expected to modify the biofunctionality as observed in previous experiments on the cell response. The co-implantation of calcium and phosphorus samples, which showed best results in the performed tests (biological and physical), leads to a strong modification of the chemical surface composition.     

The behaviour of mosaic blocks and electrical properties of polysilicon under ion implantation

Abstract

The change in microstrains ε, block sizes L and in the temperature dependences of conductivity of polysilicon with the grain size 30-40nm at N⁺, Ne⁺, P⁺ ion irradiation has been studied. It is shown that ε increases while L practically is not changing up to amorphization. The change in conductivity is governed by an increase in the density of states near the Fermi level and depends both on the damage rate for the given ions and their chemical activity.     

A comparative study of gamma-ray interaction and absorption in some building materials using Zeff-toolkit

The gamma-ray shielding behaviour of a material can be investigated by determining its various interaction and energy-absorption parameters (such as mass attenuation coefficients, mass energy absorption coefficients, and corresponding effective atomic numbers and electron densities). Literature review indicates that the effective atomic number (Z_eff) has been used as extensive parameters for evaluating the effects and defect in the chosen materials caused by ionising radiations (X-rays and gamma-rays). A computer program (Z_eff-toolkit) has been designed for obtaining the mean value of effective atomic number calculated by three different methods. A good agreement between the results obtained with Z_eff-toolkit, Auto_Z_eff software and experimentally measured values of Z_eff has been observed. Although the Z_eff-toolkit is capable of computing effective atomic numbers for both photon interaction (Z_eff,PI) and energy absorption (Z_eff,En) using three methods in each. No similar computer program is available in the literature which simultaneously computes these parameters simultaneously. The computed parameters have been compared and correlated in the wide energy range (0.001–20?MeV) for 10 commonly used building materials. The prominent variations in these parameters with gamma-ray photon energy have been observed due to the dominance of various absorption and scattering phenomena. The mean values of two effective atomic numbers (Z_eff,PI and Z_eff,En) are equivalent at energies below 0.002?MeV and above 0.3?MeV, indicating the dominance of gamma-ray absorption (photoelectric and pair production) over scattering (Compton) at these energies. Conversely in the energy range 0.002–0.3?MeV, the Compton scattering of gamma-rays dominates the absorption. From the 10 chosen samples of building materials, 2 soils showed better shielding behaviour than did other 8 materials.     

半圆形容器等离子体源离子注入过程中离子动力学的两维PIC计算机模拟

利用两维particle-in-cell方法研究了半圆形容器表面等离子体源离子注入过程中鞘层的时空演化规律. 详尽考察了鞘层内随时间变化的电势分布和离子密度分布规律,离子在鞘层中的运动轨迹和运动状态,得到了半圆容器内、外表面和边缘平面上各点离子注入剂量分布规律,获得了工件表面各点注入离子的入射角分布规律. 研究结果揭示了半圆容器边缘附近鞘层中离子聚焦现象,以及离子聚焦现象导致工件表面注入剂量分布和注入角度分布存在很大不均匀的基本物理规律. 关键词： 等离子体源离子注入 鞘层 两维particle-in-cell方法 离子运动轨迹     

Ti离子注入和退火对ZnS薄膜结构和光学性质的影响

利用真空蒸发法在石英玻璃衬底上制备了ZnS薄膜,将能量80 keV,剂量1×10¹⁷ cm^-2的Ti离子注入到薄膜中,并将注入后的ZnS薄膜进行退火处理,退火温度500—700 ℃.利用X射线衍射（XRD）研究了薄膜结构的变化,利用光致发光（PL）和光吸收研究了薄膜光学性质的变化.XRD结果显示,衍射峰在500 ℃退火1 h后有一定程度的恢复;光吸收结果显示,离子注入后光吸收增强,随着退火温度的上升,光吸收逐渐降低,吸收边随着退火温度的提高发生蓝移;PL显示,薄 关键词： ZnS薄膜 离子注入 X射线衍射 光致发光     

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基于感应耦合等离子体(ICP)技术设计了一套用于在硅基片上制作形成超浅结的等离子体浸没注入(PIII)系统。该ICP PIII系统工作腔室为圆柱形,采用射频功率源,注入偏压源为一脉冲直流电压源,系统与Langmiur探针相连。探针诊断结果表明,该系统的等离子体离子密度达到1017m-3,离子密度径向均匀性达到3.53%。硼和磷的超低能注入试验的二次离子质谱测试结果表明：掺杂离子注入深度在10nm左右,最浅的注入深度为8.6nm(在注入离子密度为1018cm-3时);注入离子剂量达到了1015cm-2以上;掺杂离子浓度峰值在表面以下;注入陡峭度达到了2.5nm/decade。     

Optical and paramagnetic properties of natural diamonds implanted with hydrogen ions

We used IR spectroscopy and electron spin resonance (ESR) to investigate defect reconstruction processes occurring in diamond crystals due to their implantation with H⁺ ions with energies of 65–350 keV and subsequent isochronous annealing in the temperature range 250–1550°C. We found that most of the hydrogen in diamonds implanted with protons is in an IR-inactive state. Magnetic hysteresis related to radiation defects in diamond is observed for the first time at room temperature using ESR. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 4, pp. 485–490, July–August, 2007.