Design study and beam technology development of the JAERI-Takasaki positron research facilities

The JAERI -Takasaki is now going to promote the R and D on the positron beam of the 1010 e+/s intensity, whereby the four ion accelerators are available. Combined irradiation of the ion and positron beams is one of the useful tools for studying advanced areas including material and biotechnology. The three-dimensional Monte Carlo code is developed for tracing the positron behavior from its birth to formation of the slow component. Evaluations by this code indicate that the 100 MW 100 kW-electron linear accelerator is adequate to the required beam intensity. The feasibility of construction is studied based on the beam instability and thermal analyses. The rotating converter is developed for the high beam intensity. The moderator system is proposed for the multi-channel monochromatic positron beams on the bases of the computer code calculation. The efficiency of the moderator is improved by the structural optimization of the target system. The layout of the facilities in the building has been figured out. The construction of the slow positron beam line is completed where the electrostatic potential of the maximum 30 kV is used. The fast positron facilities will be completed in 1997. The facilities have the capability of the energy of 1 MeV, the pulse width less than 100 psec. (Y. Tanaka)