Hirofumi Fukuyama

Development of a compact nuclear microprobe system and its application to the analysis of titanium castings

Abstract A compact nuclear microprobe system with a new configuration and a number of analysis functions has been developed. The overall size of the system is 4.5 (length) × 2.5 (width) × 1.8 (height) m. To estimate the focusing performance, secondary electron microscopic (SEM) images of line and 2-dimensional patterns of Au on a Si substrate were obtained. Stripes of 0.75 and 1 μm were resolved in horizontal and vertical directions, respectively. Micro-PIXE has been applied to the analysis of Ti castings. Two kinds of casting samples were prepared. They were cast by using a phosphate bonded or an ethylsilicate bonded investment. It was found that Si and P in the former casting diffuse down to at least 160 and 80 μm under the surface and Si in the latter down to at least 40 μm. It was also found that these values of diffusion depths are in good correlation with the results of a micro-Vickers hardness test.

Compact nuclear microprobe system for RBS/PIXE

A compact nuclear microprobe system for RBS/PIXE with an overall size of 4.5 m (length) × 2.5 m (width) × 1.8 m (height), including an accelerator, has been created by arranging an accelerator, objective slits, an E × B filter and a quadrupole magnet doublet in order in a straight line. The beamline was designed to produce a collimated beam with a divergence of less than 0.01° for channeling measurements, as well as a microprobe with a spot size of about 1 μm for micro-RBS/PIXE measurements, by only adjusting the lens currents. A measuring chamber has a goniometer of our own original design with four axes and a revolving disk head holding 30 samples for automatic sequential measurements. The combination of two kinds of beam and two sample manipulators make the system extremely versatile. This paper describes fully the system design and details of the main components. The optical aberration caused by an E × B filter is discussed using computer simulation, and measured ion contamination due to the arrangement of the system in a straight line is evaluated.

Development of a compact high-resolution RBS system for monolayer analysis

A compact high-resolution RBS system consisting of a 90° sector magnetic spectrometer and a 500 kV accelerator is developed. Energy resolution of the spectrometer is designed to be 0.1% at an acceptance angle of 0.4 msr in an energy range of 27%. The dimensions of the full system are 3.8 m (L)×2.8 m (W)×2.35 m (H) including the accelerator. The system is shown to be capable for monolayer analysis as was designed.

Depth profile analysis of helium in silicon with high-resolution elastic recoil detection analysis

Helium depth profiling in silicon was investigated by high-resolution elastic recoil detection analysis (HERDA) using a high-resolution Rutherford backscattering spectrometry system. A 0.7 μm Mylar film was installed in front of the detector of this system to eliminate the background signals originating from incident nitrogen ions scattered at the sample surface. This film successfully eliminated the background signals without the loss of helium signals or serious degradation of the depth resolution. The HERDA has several attractive features for helium depth profiling in silicon, including high sensitivity (detection limit of 1 at. % or less), excellent depth resolution (less than 1 nm), and good quantitative accuracy, giving it significant advantages over other surface analysis methods such as secondary ion mass spectrometry.

Evaluation of Detection Angle Change Mechanism of High Resolution RBS System

A new high resolution RBS (HRBS) system consisting of a magnetic spectrometer and a compact vertical small accelerator is developed. A detection angle change mechanism rotating around Y axis combined a spectrometer, a measurement chamber, a goniometer and a detection chamber is newly designed and installed. In order to evaluate stability and repeatability of a detection angle change mechanism, Si element peak edge channel on a position sensitive detector is measured by using ion beam. Edge position repeatability less than 1 channel for atomic level surface characterization has been performed.

DESIGN OF A NEW HIGH VOLTAGE GENERATOR FOR ION BEAM ANALYSIS

Abstract A new type of high voltage generator has been designed, with the aim of developing a compact, inexpensive and easily-maintained generator for energetic ion beam analyses. It has a similar structure to a rotating disk-type generator, such as the Disktron, and has the potential to have a compact size and satisfactory generating voltage stability. Its generating mechanism is, however, rather similar to rectifier type generators, such as the Cockcroft-Walton and the Schenkel types, so that there are no friction components which might produce a lot of dust, so opening the high pressure tank for cleaning is an infrequent operation. The proposed generator can be produced relatively inexpensively. A single module model has been built and it was confirmed that the proposed generating mechanism functions successfully.

A compact wavelength-dispersive X-ray spectrometer for particle-induced X-ray emission analysis

Abstract A new compact wavelength-dispersive X-ray spectrometer has been developed for our compact high energy ion microprobe system (“mikro-i”). This spectrometer is designed to detect four light elements, boron, carbon, nitrogen and oxygen. Using two multilayer X-ray analyzers, multilayer benders cut from a single metal block and a gas-proportional counter with a 150 mm × 20 mm wide, 1 μm thick polymer window, the compact dimensions of the spectrometer are achieved. The result of initial X-ray detection has shown that the spectrometer has less than 21 eV (FWHM) resolution for each element, small enough to discriminate their characteristic X-ray lines from disturbing ones. Also, the same detection limit has been shown for oxygen for the trace element analysis.

New MV-class generator

A new type of high voltage generator has been designed with the aim of developing a compact, inexpensive and easily maintained generator for energetic ion beam analyses such as Rutherford backscattering and particle induced X-ray emission. It consists of several rotating disks and fixed plates made of insulator with metal plates. Since the structure is similar to a rotating disk-type generator, such as the Disktron, it should basically have the potential to display indicators such as compact size and reliable generated voltage stability. Its generating mechanism is, however, rather similar to rectifier-type generators, such as the Cockcroft- Walton and the Schenkel types, so that there are no friction components which might produce a lot of dust, thus opening the high pressure tank for cleaning is an infrequent operation. The proposed generator can be produced relatively inexpensively. A single module model has been built and its generating ability was studied. As a result, it was confirmed that the proposed generating mechanism functions successfully.