[en] A pulse septum magnet used for beam injection and extraction is commonly installed in a vacuum chamber. In order to cool the magnet coil, metal tubes are attached to it by silver weld, and are drawn from the vacuum to the atmosphere through a flange of the chamber. For the electrical isolation of the coil from the flange, metalized ceramic joints should be inserted in the metal tubes between the coil end and the flange. But water leak into vacuum system will come out within a few years by electric corrosion at the silver weld of the ceramic joint. In our improved magnet, the metal tubes have not any joints in the vacuum chamber, and are drawn from the vacuum to the atmosphere with the same electric potential as coil's through isolated gauge-ports in the flange. As the metal tubes are now isolated by ceramic tubes in the atmosphere, the water leak from the silver weld can be repaired easily. Another improvement is a supporting system of the magnet. The magnet is hung from the cover plate of the box type chamber. So, if a trouble of the magnet happens, we have only to change it for a spare with a cover plate. The position of the top flange of the chamber is arranged so accurately to the beam line that there is no necessary of the resetting after the change of spare. In this paper, the method to fabricate the improved magnet is discussed in detail. (author)

[en] A ³He-⁴He dilution refrigerator with cooling power of 500 μW/100mK and circulation rate 600 μmol/s has been produced in the machine shop of Research Institute for Scientific Measurement. The apparatus is designed for the measurement of the de Haas van Alphen effect of the heavy electron system in magnetic fields up to 14.5 T. The various techniques of the constructing procedures including the cryostat and heat exchangers are reported. (author)

[en] This liquid nitrogen piping with total length of about 50 m was made and installed to supply the liquid nitrogen for heat insulating shield to three superconducting magnets for deflection and large super-conducting magnet for detection in the π-meson beam line used for high energy physics experiment in the National Laboratory for High Energy Physics. The points considered in the design and manufacture stages are reported. In order to minimize the consumption of liquid nitrogen during transport, vacuum heat insulation method was adopted. The construction period and cost were reduced by the standardization of the components, the improvement of welding works and the elimination of ineffective works. For simplifying the maintenance, spare parts are always prepared. The construction and the procedure of assembling of the liquid nitrogen piping are described. The piping is of double-walled construction, and its low temperature part was made of SUS 316L. The super-insulation by aluminum vacuum evaporation and active carbon were attached on the external surface of the internal pipe. The final leak test and the heating degassing were performed. The tests on evacuation, transport capacity and heat entry are reported. By making the internal pipe into smaller size, the piping may be more efficient. (Kako, I.)

[en] In the X-ray optical system for the photon factory facility being constructed now in the National Laboratory for High Energy Physics, total reflection mirrors occupy important position. The shapes of mirrors are both plane and curved surface, and the sizes are various. Especially concerning hard X-ray, the required accuracy of the shapes and surface roughness is high. Thereupon mirrors were machined by elastic emission machining (EEM) developed by Mori et al. of Osaka University, and the flatness and surface roughness were examined. The materials machined were Pyrex and copper, the mirror finish of which is difficult. The results are reported. In this machining method, the liquid in which very fine powder is uniformly dispersed and suspended in water was used. By approaching a rotating urethane ball to a work surface, the gap of about 1 μm was formed between them utilizing fluid bearing-like flow arising there. The machining was carried out by colliding the fine particles in suspension to a minute region of the work surface. In order to obtain an arbitrary curved surface, the numerical control according to the variable controling the amount of machining was made. In the case of glasses, the amount of machining was able to be controlled to about 0.01 μm. As for polycrystalline copper, the machining was difficult, and the suitable conditions must be sought hereafter. (Kako, I.)

[en] Photon Factory needs a focusing mirror with high form accuracy of 0.01 μm/100 mm for utilizing SOR (Synchrotron Orbital Radiation). In order to finish a focusing mirror with such a high accuracy by NC EEM (Numerically Controlled Elastic Emission Machining), the measurement of the surface profile of preworked mirror should be made with enough accuracy. However, the measuring method or the measuring instrument with such a high accuracy of 0.01 μm/100 mm has not been developed yet. In the present study, the normal vectors at each points on the mirror surface are determined by making the incident light beam on the mirror surface and the reflected beam at that point coincident, the surface gradients at each points are calculated from the normal vector and the surface profile is obtained by integrating the gradients. The measuring instrument was constructed according to the above principle of measuring method. The surface profile of the mirror with the size of 100 mm square and with the radius of curvature of 5550 mm was measured by the present instrument with the accuracy of 0.01 μm/100 mm. (author)