Electromagnetic field effects on nucleon transverse momentum for heavy ion collisions around 100 A MeV

Effective atomic numbers for photon energy absorption(ZPEA_(eff)) and their corresponding electron numbers (NPEA_(eff)), and effective macroscopic removal cross sections of fast neutrons(RR) were calculated for 27 different types of three-dimensional dosimeters, four types of phantom materials, and water. The values of ZPEA_(eff) and NPEA_(eff) were obtained using the direct method for energies ranging from 10 keV to 20 MeV. Results are presented relative to water, for direct comparison over the range of examined energies. The effect of monomers that are used in polymer gel dosimeters on the water equivalence is discussed. The relation between Σ_R and hydrogen content was studied. Micelle gel dosimeters are highly promising because our results demonstrate perfect matching between the effective atomic number, electron density number, and fast neutron attenuation coefficient of water.     

A study on swift (∼100 MeV) heavy ion irradiated Ni films on Si substrates

Ni thin films (∼50 nm) on silicon substrates have been irradiated from 100 MeV swift heavy ions of Fe⁷⁺ with a fluence of 10¹² ions cm⁻². SEM studies show a nice feature of interwoven grains which looks like a knitted network which has been resolved as a spherical grainy structure from AFM studies. Chemical phase identification of the grains has been done from XRD studies and it is found that there is a formation of the Ni₂Si silicide phase having average grain size of ∼70 nm. The devices have also been characterized from I-V characteristics before and after the irradiation at varying temperature from LN₂ to room temperature. The current across the irradiated interface has increased by two orders of magnitude as compared to the unirradiated ones and show a nearly temperature independent behaviour. MR (magnetoresistance) has been studied from the current flow data in magnetic fields up to 10 kG. Unirradiated devices do not show any effect on current transport in external magnetic field. M-H characteristics of the irradiated devices show the typical magnetic behaviour of nano particles like superparamagnetic behaviour. The MR features has been related to the M-H variations. The observed results show the formation of magnetic nano grains due to interfacial intermixing in these devices of Ni/n-Si. The role of swift heavy ions for nano grain fabrication has been discussed and the observed properties have been understood by considering the formation of a nano magnetic granular phase.     

Search for the chiral magnetic effect in heavy ion collisions

Quark interactions with topological gluon fields in quantum chromodynamics can yield local P and CP violations that could explain the matter–antimatter asymmetry in our universe. Effects of P and CP violations can lead to charge separation under a strong magnetic field, a phenomenon called the chiral magnetic effect(CME).Early measurements of the CME-induced charge separation in heavy ion collisions are dominated by physics backgrounds. This report discusses the recent innovative efforts in eliminating those backgrounds, namely by eventshape engineering, invariant mass dependence, and reaction and participant plane comparison. The backgroundfree CME measurements using these novel methods are presented.     

A new stopping power parameterization for 0.1-15 MeV/nucleon heavy and superheavy ions in solids and gases

Electronic stopping powers of heavy ions in several media are deduced from the corresponding proton data by using new effective charge parameterizations. Separate sets of parameters were deduced for solid and gaseous materials using the available data for heavy ions in the energy range from 0.1 to 15 MeV/nucleon. Using these results, predictions are made for stopping powers of heavy and superheavy elements with Z = 100-130 in the energy range of 0.5-15 MeV/nucleon.     

Optical absorption and thermoluminescence studies in 100 MeV swift heavy ion irradiated CaF2 crystals

Pure and Ytterbium (Yb) doped Calcium fluoride (CaF₂) single crystals were irradiated with 100 MeV Ni⁷⁺ ions for fluences in the range 5 × 10¹¹-2.5 × 10¹³ ions cm⁻². The irradiated crystals were characterized by Optical absorption (OA) and Thermoluminescence (TL) techniques. The OA spectra of ion irradiated pure CaF₂ crystals showed a broad absorption with peak at ∼556 nm and a weak one at ∼220 nm, whereas the Yb doped crystals showed two strong absorption bands at ∼300 and 550 nm. From the study of OA spectra, the defect centers responsible for the absorption were identified. TL measurements of Ni⁷⁺ ion irradiated pure CaF₂ samples indicated a strong TL glow with peak at ∼510 K. However, the Yb doped crystals showed two TL glows at ∼406 and 496 K. The OA and TL intensity were found to increase with increase of ion fluence upto 1 × 10¹³ ions cm⁻² and thereafter it decreased with further increase of fluence. The results obtained are discussed in detail.     

Study of 160 MeV Ni ion irradiation effects on electrodeposited polypyrrole films

Conducting polymer polypyrrole thin films doped with LiCF₃SO₃, [CH₃(CH₂)₃]₄NBF₄ and [CH₃(CH₂)₃]₄NPF₆ have been electrodeposited potentiodynamically on ITO coated glass substrate. The polymer films are irradiated with 160 MeV Ni¹²⁺ ions at three different fluences of 5 × 10¹⁰, 5 × 10¹¹ and 3 × 10¹² ions cm⁻². An increase in dc conductivity of polypyrrole films from 100 S/cm to 170 S/cm after irradiation with highest fluence is observed in four-probe measurement. X-ray diffractogram shows increase in the crystallinity of the polypyrrole films upon SHI irradiation, which goes on increasing with the increase in fluence. Absorption intensity increase in the higher wavelength region is observed in the UV–Vis spectra. The SEM studies show that the cauliflower like flaky microstructure of the surface of polypyrrole films turns globular upon SHI irradiation at fluence 5 × 10¹¹ ions cm⁻² and becomes smooth and dense at the highest fluence used. The cyclic voltammetry studies exhibit that the redox properties of the polypyrrole films do not change much on SHI irradiation.     

Experimental study on heavy ion single-event effects in flash-based FPGAs

With extensive use of flash-based field-programmable gate arrays(FPGAs) in military and aerospace applications, single-event effects(SEEs) of FPGAs induced by radiations have been a major concern. In this paper, we present SEE experimental study of a flash-based FPGA from Microsemi Pro ASIC3 product family. The relation between the cross section and different linear energy transfer(LET) values for the logic tiles and embedded RAM blocks is obtained. The results show that the sequential logic cross section depends not too much on operating frequency of the device. And the relationship between 0 →1 upsets(zeros) and 1 →0 upsets(ones) is different for different kinds of D-flip-flops. The devices are not sensitive to SEL up to a LET of 99.0 Me V cm2/mg.Post-beam tests show that the programming module is damaged due to the high-LET ions.     

一台用于重离子鉴别的Bragg曲线谱仪

本文介绍制作的一台用于重离子鉴别的Bragg曲线谱仪。它是一种电场平行于入射粒子方向的全阻止型电离室。其性能用ThC-C’α源和~(252)Cf源进行了测试。对8.785MeV α粒子(ThC’源)能量分辨好于1％,电荷分辨Z/ΔZ=50。     

Research on Damage Effects of 100 MeV Protons on A375 Cells

<正>Proton therapy,due to its advantages in killing tumor cells and damaging normal tissues,has become one of the most important physical therapies for treating tumors in the world.It can greatly improve the cure rate of tumors that are ineffective by conventional methods.In this     

Experimental study on heavy ion single event effects in SOI SRAMs

Silicon-on-insulator (SOI) technologies have been developed for radiation-hardened military and space applications. The use of SOI has been motivated by the full dielectric isolation of individual transistors, which prevents latch-up. The sensitive region for charge collection in SOI technologies is much smaller than for bulk-silicon devices potentially making SOI devices much harder to single event upset (SEU). In this study, 64 kB SOI SRAMs were exposed to different heavy ions, such as Cu, Br, I, Kr. Experimental results show that the heavy ion SEU threshold linear energy transfer (LET) in the 64 kB SOI SRAMs is about 71.8 MeV cm²/mg. Accorded to the experimental results, the single event upset rate (SEUR) in space orbits were calculated and they are at the order of 10⁻¹³ upset/(day bit).     

一个用于重离子飞行时间测量的平行板雪崩探测器

平行板雪崩探测器很早就用于核物理实验工作。但由于性能的限制,没有被广泛采用;直至七十年代中期,经过较大改进,作为一种精确的时间信号探测器,才又被用于重离子物理实验。由于平行板雪崩探测器输出信号上升时间快、工作介质厚度薄、无辐照损伤、有效面积可以做得相当大、不易受杂散电子干扰等,特别适宜作为用于重离子物理实验的透射型时间信号探测器。通常,平行板雪崩探测器由两片平行电极组成,中间为稀薄的工作气体,两电极间保持恒定的电压。被探测的带电粒子垂直于电极而穿过工作气体,产生原电离,     

Irradiation effects with 100 MeV Xe ions on optical properties of Al-doped ZnO films

Al-doped ZnO (AZO) films are known as n-type transparent semiconductors. We have investigated the effects of 100 MeV Xe ion irradiation on the optical and structural properties of AZO films, which were prepared on SiO₂ glass at 400 °C by using a RF-magnetron sputtering deposition method. We discuss relationships between these property modifications and the recent observations of the conductivity increase by ion irradiation. It is suggested that the band-gap modification has more close relation with the conductivity increase than the structural modification.     

100keV金属表面改性离子注入与混合两用机

叙述了１００ｋｅＶ金属表面改性离子注入与混合两用机的总体结构及各主要部件的技术参数。该机经过调试各项主要指标已达到设计要求，工作稳定可靠，已开始金属材料表面改性实验。     

重离子辐照对红酵母的诱变作用

应用重离子加速器的50MeV／u^12C^6 重离子对胡萝卜素生产菌-红酵母(Rhodotorula RY Strain)进行辐照处理,经酵母发酵实验,发现50MeV／u^12C^6 重离子对胡萝卜素生产菌-红酵母具有诱变作用。初步筛选到了胡萝卜素产量有变化的辐照变异菌株,并对这些辐照变异菌株进行了RFLP(限制性片段长度多态性)和RAPD(随机扩增DNA多态性)分析,这些工作为工业上利用重离子对胡萝卜素生产菌进行诱变育种展现了新的前景。     

MeV Si ion beam modification effects on the thermoelectric generator from Er0.1Fe1.9SbGe0.4 thin film

Effective thermoelectric materials and devices have a low thermal conductivity and a high electrical conductivity. The performance of the thermoelectric materials and devices is shown by a dimensionless figure of merit, ZT. The purpose of this study is to improve the figure of merit of the single layer of Er_0.1Fe_1.9SbGe_0.4 thin film used as thermoelectric generators. We have deposited the monolayer of Er_0.1Fe_1.9SbGe_0.4 thin film on silicon and silica substrates with thickness of 302 nm using ion beam assisted deposition (IBAD). Rutherford backscattering spectrometry (RBS) was used to determine the total film thickness and stoichiometry. The MeV Si ion bombardments were performed on single layer of Er_0.1Fe_1.9SbGe_0.4 thin films at five different fluences between 5 × 10¹³?5 × 10¹⁵ ions/cm².The defect and disorder in the lattice caused by ion beam modification and the grain boundaries of these nanoscale clusters increase phonon scattering and increase the chance of annihilation of the phonon. The increase of the electron density of states in the miniband of the quantum dot structure formed by bombardment also increases the Seebeck coefficient and the electrical conductivity. We measured the thermoelectric efficiency of the fabricated device by measuring the cross plane thermal conductivity by the 3rd harmonic (3ω) method, the cross plane Seebeck coefficient, and the electrical conductivity using the Van Der Pauw method before and after the MeV ion bombardments.     

重离子束辐照细胞研究的文献计量学分析

应用文献计量学方法和相应的应用软件,借助Web of Science平台对重离子束辐照细胞这一研究主题的相关文献、作者、期刊、机构以及关键词进行定量和系统考察。结果显示,重离子束辐照细胞研究在1990年之后日益活跃并深入;不同品质的重离子束辐照诱导不同类型细胞会产生不同的生物学效应、旁观者效应及其机制、重离子束辐照细胞生物学效应评估模型、重离子束治疗癌症过程中辐照品质选择与控制模型以及相应的计算机程序是该研究主题的重要内容;引入特定指数推测所得该研究主题重要学术期刊与Nature,Proceedings of the National Academy of Sciences of the United States of America,Cancer Research等期刊之间有较高的共被引频次,表明更多科学前沿的突破性成果和思路应用于该主题研究中;此外,该研究主要集中于少数国家、少数机构、少数作者,并且合作相对较少。     

重离子辐照对肺腺癌A549细胞的影响及其机制研究

探讨重离子射线对A549细胞粘附、迁移和侵袭的效应及相关机制。对指数生长的A549细胞经过不同剂量重离子射线(12C6+)辐照后,通过MTS法测定粘附能力变化;用Transwell法检测细胞迁移和侵袭能力;采用荧光定量(RT-PCR)法检测细胞中MMP-2及MMP-9的m RNA表达水平。结果显示,12C6+重离子辐照后细胞粘附能力增强,呈剂量依赖性关系(t=0.014、0.055、0.059,p0.05);随着吸收剂量的增加,迁移能力显著下降(t=4.449、3.193、3.162,p0.05),侵袭能力也随之下降(t=3.674、3.114、3.271,p0.05),显著减弱细胞的转移能力;并且重离子12C6+辐照后,MMP2和MMP9 m RNA表达量显著下调(p0.05)。结果表明,12C6+重离子能促进A549细胞的粘附能力,显著抑制A549细胞的迁移和侵袭能力,这可能与MMP-2和MMP-9表达调节有关。     

快重离子束引起的Cu-Si膜系的两种不同类型的增强附着效应

对沉积在N型半导体硅上的Cu薄膜用几MeV的Cl离子进行了不同剂量的辐照实验以观测其增强附着行为。结果表明,Cu-Si膜系存在两种不同类型的增强附着效应。用扫描电镜对低剂量轰击出现附着增强区域的硅基底表面进行观察,未发现任何微裂现象。这与人们在解释Au-SiO_2膜系出现类似增强附着时提出的微裂观点不相符合。     

Effects of 160 MeV Ni ion irradiation on polypyrrole conducting polymer electrode materials for all polymer redox supercapacitor

Electronically conducting polymers are suitable electrode materials for high performance supercapacitors, for their high specific capacitance and high dc conductivity in the charged state. Supercapacitors and batteries are energy storage and conversion systems which satisfies the requirements of high specific power and energy in a complementary way. Ion beam {energy > 1 MeV} irradiation on the polymer is a novel technique to enhance or alter the properties like conductivity, density, chain length and solubility.

Conducting polymer polypyrrole thin films doped with LiClO₄ are synthesized electrochemically on ITO coated glass substrate and are irradiated with 160 MeV Ni¹²⁺ ions at different fluence 5 × 10¹⁰, 5 × 10¹¹ and 3 × 10¹² ions cm⁻². Dc conductivity measurement of the irradiated films showed 50–60% increase in conductivity which is may be due to increase of carrier concentration in the polymer film as observed in UV–Vis spectroscopy and other effects like cross-linking of polymer chain, bond breaking and creation of defects sites. X-ray diffractogram study shows that the degree of crystallinity of polypyrrole increases in SHI irradiation and is proportionate to ion fluence. The capacitance of the irradiated films is lowered but the capacitance of the supercapacitors with irradiated films showed enhanced stability compared to the devices with unirradiated films while characterized for cycle life up to 10,000 cycles.