NARROW NUCLEAR-RESONANCE POSITION OR CROSS-SECTION SHAPE MEASUREMENTSWITH A HIGH-PRECISION COMPUTER-CONTROLLED BEAM ENERGY SCANNING SYSTEM

The relative positions, intensity and shape of narrow resonances (Gamm a approximate to 100 eV) in (p, gamma), (p, alpha gamma) and (p, p'gam ma) reactions induced on the isotopes C-13, N-15, O-18, F-19, Na-23, M g-24, Al-27, Si-29, Si-30 and Cr-52 were investigated in the energy ra nge from 150 to 2500 keV, using a fully automatic hysteresis free ener gy scanning system. The energy differences between the resonance posit ions were measured with optimum accuracy, down to around +/-100 eV. Th e results are of interest for the easy and accurate calibration of acc elerators and for determining the energy scale in the neighbourhood of resonances used for depth profiling experiments with high precision. The new set-up allows the automatic recording of nuclear reaction or e lastic scattering excitation curves over wide energy ranges, up to +/- 10% around any central energy. The results illustrate also how powerfu l a tool such a scanning system may be in various fields of ion beam a nalysis. (C) 1998 Elsevier Science B.V.