Observation of the New Heavy Neutron-Rich Isotope 238Th

A new nuclide 238Th was produced via multinucleon transfer reaction by 60 MeV/u 18O ion irradiation of the natural uranium. The thorium was radiochemically separated from the mixture of uranium and reaction products. The growth and decay of 238Pa gamma rays was observed, identifying the 238Pa parent as 238Th. The half-life of 238Th was determined to be 9.4±2.0 min.