| Popis: |
Measurements of the pulse height defect in a silicon surface barrier detector, with fission fragments whose energies were degraded in air, show that the defect is approximately constant in the fragment energy range 25–100 MeV. The results contradict an earlier hypothesis that the defect is caused by recombination of electron-hole pairs in the dense plasma produced by the fragment at the beginning of its track. A coincidence arrangement permitted separate studies of the median light and median heavy fragments. At increased fields in the detector, pulse height distributions of the respective fragment groups became distorted toward greater pulse heights. This result is interpreted to mean that, rather than decreasing recombination, the increased field causes charge multiplication in the counter. The onset of the multiplication appears to be a function of the ionization density in the fragment track. |
