The nuclear microprobe at the University of Arizona

A nuclear microprobe has been operational at the University of Arizona since early 1994. It utilizes a magnetic quadrupole doublet (model QL-300 from Microscope Associates, Inc.) with an 11 mm diameter aperture and lens lengths of 6 cm each. The magnetic pole tips are electrically insulated to enable electric rotational alignment and beam rastering by application of varying voltages to the pole tips. Ion beams are obtained from a 5.5 MV model CN, High Voltage Engineering Corp. Van de Graaff accelerator with a Penning type ion source. Present mininum beam spot size is about 2 μm obtained with a 4 MeV H₂⁺ beam with a current of about 40 pA. To date, the instrument has been successfully used to map concentrations of Hg, Cr, and As in rabbit renal slices using PIXE.     

Early works on the nuclear microprobe for microelectronics irradiation tests at the CEICI (Sevilla, Spain)

Particle radiation effects are a fundamental problem in the use of numerous electronic devices for space applications, which is aggravated with the technology shrinking towards smaller and smaller scales. The suitability of low-energy accelerators for irradiation testing is being considered nowadays. Moreover, the possibility to use a nuclear microprobe, with a lateral resolution of a few microns, allows us to evaluate the behavior under ion irradiation of specific elements in an electronic device. The CEICI is the new CEnter for Integrated Circuits Irradiation tests, created into the facilities at the Centro Nacional de Aceleradores (CNA) in Sevilla-Spain. We have verified that our 3 MV Tandem accelerator, typically used for ion beam characterization of materials, is also a valuable tool to perform irradiation experiments in the low LET (Linear Energy Transfer) region.     

Assessment of atmospheric heavy metal deposition in the Tarkwa gold mining area of Ghana using epiphytic lichens

In situ lichens (Parmelia sulcata) have been used to assess atmospheric heavy metal deposition in the Tarkwa gold mining area of Ghana. Total heavy metal concentrations obtained by instrumental neutron activation analysis (INAA) were processed by positive matrix factorization (PMF), principal component (PCA) and cluster (CA) analyses. The pollution index factor (PIF) and pollution load index (PLI) criteria revealed elevated levels of Sb, Mn, Cu, V, Al, Co, Hg, Cd and As in excess of the background values. The PCA and CA classified the examined elements into anthropogenic and natural sources, and PMF resolved three primary sources/factors: agricultural activities and other non-point anthropogenic origins, natural soil dust, and gold mining activities. Gold mining activities, which are characterized by dominant species of Sb, Th, As, Hg, Cd and Co, and significant contributions of Cu, Al, Mn and V, are the main contributors of heavy metals in the atmosphere of the study area.     

PIXE and the nuclear microprobe: Tools for quantitative imaging of complex natural materials

The 40 year history of nuclear microscopy has seen sustained progress in the development of technology needed to improve PIXE analysis and trace element imaging performance. Focussing systems have been developed for improved spatial resolution, detector systems have evolved to collect more signal, full-spectral scanning data acquisition approaches have been devised. The complexity of PIXE spectra has driven the development of techniques for fitting numerous overlapping components in spectra for quantitative analysis, methods have been developed for specialized problems in geology, such as the analysis of fluid and melt inclusions in minerals, and techniques for the deconvolution of elemental components in full-spectral scanning data sets have been developed to produce accurate element images. The future of nuclear microscopy using PIXE is promising. Lens system approaches have evolved and point towards ‘full bore’ acceptance, optimal matching to accelerator emittance, high current density and sub-μm spatial resolution using many nA beam currents. Detector arrays and integrated data acquisition and scanning systems are emerging that can collect all events across a large solid-angle collection area and process these events for element image display in real-time. The combination of these advances provides a path to greatly enhanced sensitivity for PIXE analysis and imaging and a more productive user experience. The emergence of detector array approaches for scattered particles and reaction products, and the development of software tools for coupled PIXE-RBS data reduction, suggest a path towards complementary RBS and NRA tools. The stage is set for an exciting and productive future for PIXE imaging on the nuclear microprobe.     

球载核径迹探测器用于研究重核辐射生物效应

介绍塑料核径变探测器用于研究气球高度相对论宇宙线重核辐射生物效应的“Ｂｉｏｓｔａｃｋ”实验方法和两次气球搭载实验的初步结果。     

注入低能重离子在模拟细胞中的能量沉积

用Ｍｏｎｔｅ Ｃａｒｌｏ法模拟计算了３０ｋｅＶ和２００ｋｅＶ的Ｎ＾＋与１１０ｋｅＶ的Ｆｅ＾＋模拟细胞中本身及级联离子非弹性散射产生的电子，分子振动的能量沉积；讨论了电子分子振动的总能量沉积的深度分布。     

Use of UV radiation for removing petroleum oils from water at nuclear power plants

Institute of Physical Chemistry, Russian Academy of Sciences. Translated from Atomnaya Énergiya, Vol. 73, No. 6, pp. 478-482, December, 1992.     

重离子注入生物材料质量沉积效应评述

前人曾用重离子束注入生物小分子，借助先进的仪器分析手段，对重离子注入质量沉积进行了初步研究，但质量沉积对处于生命状态下的活生物体组织细胞和生物大分子所带来的生物学效应，即质量沉积效应的研究还未见报道。将来可用放射性重离子束注入活细胞和生物分子，借助放射自显影示踪、放射性测量和分子生物学等研究技术对重离子注入质量沉积效应开展进一步研究。     

容器内核材料监视技术的可行性研究

通过辐射探测器对装在容器内的核材料的辐射场进行了长时间的监测,研究了用辐射探测器在环境保持不变时,对装在容器内的核材料进行较长时间监控的可行性。此外人为改变储存间温度在20～30℃和20～35℃之间变化,实验研究了在变温环境下,温度对辐射探测器的影响以及探测器对容器内核材料实时监控的可行性。     

多用途核数据库HENDL2.0/MG/MC的重核临界基准校验

为适应聚变-裂变混合堆设计及其相关研究的需求制作混合多用途核数据库HENDL(Hybrid Evaluated Nuclear Data Library)的升级版本HENDL2.0.评价核数据来源主要选用美国公布的ENDF/B-Ⅶ.0库和国际原子能机构(IAEA/NDS)发布的聚变库FENDL-2.1.利用蒙特卡罗粒子输运程序MCNP以及FDS团队自主研发的大型集成多功能中子学计算与分析系统VisualBUS程序进行模拟计算,对已有的一些数据较为完备的基准实验例题进行基准测试和比较分析以检验混合库HENDL2.0的有效性和可信性.     

Damages induced by heavy ions in titanium silicon carbide: Effects of nuclear and electronic interactions at room temperature

Thanks to their refractoriness, carbides are sensed as fuel coating for the IVth generation of reactors. Among those studied, the Ti₃SiC₂ ternary compound can be distinguished for its noteworthy mechanical properties: the nanolamellar structure imparts to this material some softness as well as better toughness than other classical carbides such as SiC or TiC. However, under irradiation, its behaviour is still unknown. In order to understand this behaviour, specimens were irradiated with heavy ions of different energies, then characterised. The choice of energies used allowed separation of the effects of nuclear interactions from those of electronic ones.     

A study of barium accumulation in desmids using the Oxford scanning proton microprobe (SPM)

Within a group of unicellular freshwater algae called desmids there is a genus, Closterium, the cells of which are known to store BaSO₄ microcrystals in vacuoles situated at each end of the cell.In studies involving Closterium moniliferum cells grown in cultures containing different concentrations of BaCl₂, it was observed that the barium uptake, as measured by the Oxford SPM, was not lowest at the lowest concentrations of BaCl₂ to which the cells were exposed (0.001 and 0.01 mg/l but unexpectedly at a median concentration of 1.0 mg/l.In a second study on Closterium moniliferum cells grown in a culture containing 0.010 mg Ba/l, the rate of uptake of barium was observed to level off over a 24 h period.SPM elemental maps of Closterium cells are presented, one sample of which was grown in a normal medium and shows BaSO₄ crystals present in the terminal vacuoles, and the other sample grown in a Ba rich medium and showing BaSO₄ crystals distributed throughout the cell.     

Origin of the finite nuclear spin and its effect in intermediate energy heavy ion collisions

The heavy-ion phase-space exploration (HIPSE) model is used to discuss the origin of the nuclear spin in intermediate energy heavy-ion collision (HIC).The spin of maximal projectile-like fragment is found to depend strongly on impact parameter of a reaction system,while it relates weakly to the collision violence.Some interesting multi-fragmentation phenomena related to the spin are shown.We also found that the excitation energy in the de-excitation stage plays a robust role at the de-excitation stage in HIC.     

Defects remaining in MeV-ion-implanted and annealed Si away from the peak of the nuclear energy deposition profile

Damage has been observed in MeV-ion-implanted Si away from the maximum of the nuclear energy deposition profile, mainly around the half of the projected ion range, R_P/2. Cu gettering has been used for the detection of irradiation defects which are formed during annealing at temperatures between 700°C and 1000°C. This damage is primarily created by the implanted ions on their trajectory and consists of intrinsic defects remaining so small that they have not yet been resolved. These defects undergo a defect evolution during annealing which results in a decrease of the width of the damage layer with increasing temperature and prolonged time of the annealing.