Magnetic moments of picosecond high-spin states: experimental status and future developments

Abstract

Magnetic moments are among the most sensitive experimental quantities reflecting the structure of individual excited nuclear states because they are able to distinguish between the nature and the spin coupling of the valence particles. To explore the abilities and limitations of different theoretical models of the nucleus, it is therefore very desirable to determine g-factors with the highest possible reliability. From the experimental point of view, the accuracy achievable is limited by the fact that the effect that has to be measured is extremely small. In addition, when heavy-ion fusion-evaporation reactions are used to populate the nuclei of interest, the complex feeding mechanism inherent in this type of reaction leads to further systematic uncertainties. To overcome these difficulties a new experimental technique called recoil distance transient field technique is introduced allowing for the first time to measure g-factors of individual high-spin states with lifetimes as short as a few picoseconds populated in fusion reactions. For this γγ coincidence technique, the use of highly efficient γ-ray spectrometers is mandatory.