A plunger device for in-beam measurements of nuclear lifetimes

Abstract An experimental apparatus was built to measure life-times of excited nuclear states with the recoil-distance method (RDM). A millesimal micrometer and an electromagnetic gauge-head are used to measure the target-stopper distance, and their parallelism is tested by optical and capacitance methods. Measurements were performed in the nuclei 22 Na and 153 Dy, populated by the reactions 19 F(α, n) and 144 Nd( 12 C, 3n), respectively. A minimum target-stopper distance of ≅3 ωm has been reached.