Rutherford Backscattering spectrometry (RBS) and Particle Induced X-ray Emission (PIXE) are well-known techniques of ion beam analysis using MeV energy ions and they are used for material analysis like semiconductors, environmental analysis. RBS/PIXE systems are often relatively large with high energy accelerators, and are not very convenient for practical purposes. We describe here a new compact RBS/PIXE system with a small accelerator with original ion optics and beam line, which can produce a microprobe with a spot size of about 1 um.
Heavy charged particles transfer their energy to biological organisms through high-density ionization along the particle trajectories. The population of cells exposed to a very low dose of heavy-ion beams contains a few cells hit by a particle, while the majority of the cells receive no radiation damage. At somewhat higher doses, some of the cells receive two or more events according to the Poisson distribution of ion injections. This fluctuation of particle trajectories through individual cells makes interpretation of radiological effects of heavy ions difficult. Furthermore, there has recently been an increasing interest in ionizing radiation-induced “bystander effects”, that is, radiation effects transmitted from hit cells to neighboring un-hit cells. Therefore, we have established a single-cell/single-particle irradiation system using a heavy-ion microbeam apparatus at JAEA-Takasaki to study radiobiological processes in hit cells and bystander cells exposed to low dose and low dose-rate high-LET radiations, in ways that cannot be achieved using conventional broad-field exposures.
We have developed a method to produce a micro- or nano-sized beam of highly charged ions with a glass capillary. A transmission of 8 keV Ar8+ beam through the capillary 5 cm long with 800/24 μm inlet/outlet inner diameters was observed stably for more than 1200 s. The transmitted beam had approximately the same size as the outlet inner diameter with a beam density enhancement of about 10 and a divergence of ±5 mrad. The initial beam was guided through a capillary tilted by ±87 mrad, and it still kept the incident charge. In order to fabricate the nano-sized outlet of the capillary, a Focused Ion Beam of Ga+ with 40 kV acceleration was employed.
A microscope for hydrogen has been developed by means of micro-beam nuclear reaction analysis. The resonance nuclear reaction between proton and 15N accelerated up to ~6 MeV is used. The micro-beam of 15N ion was made by a glass capillary, which has a taper shape. Against this focused 15N ion beam, samples are scanned perpendicularly to the beam direction by stepping motors. As an application of the microscope, a patterned Y thin film covered by Pd thin film was prepared, and the sample was exposed to 1 atm hydrogen atmosphere over a night. The hydrogen distribution in this sample was investigated by using a glass capillary, which has an exit with the 50 μm diameter. As a result, a profile of nuclear reaction analysis, indicating that the hydrogen atoms are concentrated in the patterned Y thin films, was taken.
Selective cell attachment on carbon-negative-ion implanted region of polystyrene was already reported by the authors. However, the selectivity and adhesion strength in the cell pattering were partially insufficient. The adhesive proteins called extracellular matrix (ECM), in general, intervene between cell and substrate surface in the cell attachment on the solid surface. Therefore, we considered to obtain clearer selective cell attachment with tighter binding strength on the implanted region of polystyrene when these adhesive proteins precedently adsorbed on the implanted region of polystyrene. In this paper, we have investigated adsorption properties of three kinds of adhesive proteins (gelatin, fibronectin, laminin) and cell attachment properties on precedent protein adsorbed surface of polystyrene modified by carbon negative-ion implantation. Carbon negative ions were implanted into polystyrene at energy of 10 keV with dose in a range of 1×1014~1×1016 ions/cm2. After implantation, the samples were dipped in the protein solutions for 2 hours. Then, the protein adsorption ratio between implanted and unimplanted regions was evaluated by detecting amount of nitrogen atoms on the surface by X-ray photoelectron spectroscopy (XPS). As a result, the protein-precedently-absorbed sample implanted at dose more than 3×1015 ions/cm2 showed the large gelatin adsorption ratio of more than 2, where the much densely populated cell-attachment was observed more than that on the implanted region of polystyrene without precedent adsorption of protein after cell culture.
We introduce a miniature electron/ion/soft-X-ray detector mounted on a conflat flange with an outer diameter of 70 mm. It consists of an extraction/retarding electrode, microchannel plates, and a conflat flange with an outer diameter of 70 mm. This detector can be used for measurements of electrons, ions, or soft-X-rays generated in the gas phase and those emitted from surfaces.