A new UHV setup for investigations of narrow nuclear resonances with high energy resolution ion beams

A cryogenic target system has been built to study yield curves of narrow nuclear resonances. The crucial part of the UHV set-up is a liquid helium cooled sample holder mounted on a goniometer, allowing the use of gas and solid targets in the temperature range 10-600 K. Particle detectors and γ-ray detectors can be installed in close geometry to the target to achieve large solid angles. With this target system nuclear resonances in 21Ne(p, γ)22Na and 18O(p, α)15N have been investigated with high ion beam energy resolution. Effects of electronic excitation processes are clearly visible in the shape of yield curves of the 272 keV resonance in 21Ne(p, γ)22Na obtained at a temperature of ∼12 K. The width of the 151 keV resonance in 18O(p, α)15N was measured, where the data are significantly influenced by interference effects. (orig.)