Energy calibration of surface barrier detectors and ionization chambers for fission fragments

The pulseheight response X of surface barrier detectors and an axial ionization chamber has been taken for fission fragments of given mass M and energy E. Fragments of accurately known M and E were obtained from the mass separator Lohengrin at the ILL. The energies on Lohengrin were calibrated by a time-of-flight technique. Pulse-height spectra from 252Cf (sf) were recorded in parallel. It could again be shown that the Energy E is well described by the relationship E = (a+a'M)X + (b+b'M). In the case of surface barrier detectors, the calibration constants desired differ, however, markedly from previously reported values. The new constants yield for the reaction 235U(nth, f) kinetic energies of the fission fragments which are in perfect agreement with recent velocity measurements.