| Co-Investigator(Kenkyū-buntansha) |
NUMAJIRI Masaharu High Energy Accelerator Research Organization, Applied Research Laboratory, Research Associate, 放射線科学センター, 助手 (20189385)
MIURA Taichi High Energy Accelerator Research Organization, J-PARC Project, Associate Professor, 大強度陽子加速器計画推進部, 助教授 (80209717)
KONDO Kenjiro High Energy Accelerator Research Organization, Applied Research Laboratory, Professor, 共通研究施設, 教授 (20004434)
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| Research Abstract |
Free volumes in a thin film coated on a metal base plate can be studied by positron annihilation. However, In order to study the surface of polymers, a pulsed slow positron beam (PSPB) is necessary to determine the injection time in the investigated polymer. In this project, a small apparatus desk-top size to generate a PSPB using radio isotopes (RI) has been used. The bunched and pulsing beam was obtained by the RF method, in which RF field is applied on an Al tube with 2cm diameter and 5cm length. The length is determined by the flight time of positrons through the tube. Thus 40 MHz RF is used to bunch the rundum beam to a bunched beam. The width is 500 to 600ps, which is enough to study polymer samples, which have lifetimes longer than 1.5ns to 2 ns.
The apparatus to inject a pulsed and bunched beam in samples has been successfully applied to measure lifetimes of polymers : polyethylene, epoxy resin, epoxy composite, epoxy coated films on a Silicon metal. Carbon-implanted ultra-high molecular-weight polyethylene, was prepared and the surface affected by the ions was studied. The surface was distorted and the lifetime became a little longer than the balk sample. Ps formation intensity became small around the depth of the deposited position, where the carbon implanted layer is expected. The heat expansion coefficient of the surface and the bulk of epoxy resin was obtained.
The increase in the positronium formation with increasing the depth was observed in polyethylene. The skin layer of the composite materials was observed by a non destructive method. Low K films on Silicon plate, which are extensively used in IC and electric industry has been studied.
Large holes with about 50 ns positron lifetime has been successfully observed
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