Positron microscopes at KEK

This paper reports the plans of positron microscopes being built at KEK, Ts ukuba, Japan, employing used electron microscopes. The kinetic energies of positrons produced by accelerators or by nuclear decays do not have a uniqu e value but are spread in a wide range. The positron beam will be guided ne ar electron microscopes, such as a transmission electron microscope (JEM100 S) and a scanning electron microscope (JSM25S), Positrons are slowed down b y a tungsten foil, accelerated and focused on a nickel sheet. The monochrom atic focused beam will be injected into an electron microscope. The focusin g of positrons and electrons are the same in the magnetic system. The chara cteristic feature of this plan is that the electron microscopes can be used for positrons without changing the focusing system. The electron microscop e is shielded from earth's magnetic field and thus it is convenient to use electron microscopes. Imaging plates are used to detect positron images for the transmission positron microscope. (C) 2000 Elsevier Science B.V. All r ights reserved.