Experimental search for the low-energy nuclear transition in super(229) Th with undulator radiation

To search for the lowest energy nuclear isomeric transition in super(229)Th in solid samples, a novel adsorption technique which prepares super(229)Th atoms on a surface of CaF sub(2) is developed. Adsorbed super(229)Th is exposed to highly intensive undulator radiation in the wavelength range between 130 and 320 nm, which includes the indirectly measured nuclear resonance wavelength 160(10) nm. After the excitation, fluorescence from the sample is detected with a VUV sensitive photomultiplier tube. No clear signal relating to the nuclear transition is observed and possible reasons are discussed.