In order to examine the fusion neutron induced soft-error on memory ICs, two kinds of 1 Mbit CMOS SRAM ICs were irradiated with 14 MeV neutrons. The rate of soft-error upsets on the ICs was measured in situ during neutron irradiation. The number of the soft-errors increased proportionally with neutron fluence. Considering the cell population in the chip, we obtained the neutron susceptibility constant, i.e. bit soft-error cross section of 5～9×10^-14cm² for the 1 Mbit CMOS SRAMs. Also this cross section value agreed roughly with that calculated by computer simulation with a developed Monte Cairo program and the ENDF/B-VI neutron cross section data.

  This is a feasibility experimental study to apply an atomic force microscope (AFM) to observe and analyze minute etch pits on CR-39 plastic nuclear track detectors. This method makes it possible to observe more than 10⁷/cm² etch pit density produced by 135MeV/n carbon ions. It is applicable to the flux, LET and dose measurements for carbon ion cancer treatments, because the order of the ion particle density is 10⁶/cm². It is impossible to do this kind of measurements with ordinary optical microscope observation, because almost all etch pits overlap each other.

  It is observed that the etch rate ratio of carbon ions is significantly small for the very surface layer (depth ～0.1μm) of CR-39 plastic detectors comparing with that for the deeper layer (depth ～40μm). This difference in track formation sensitivity is probably due to a surface effect of the detector material itself.