Identification of new isotope Th-238

Unreported heavy neutron-rich nuclide Th-238 has been produced via a multin ucleon transfer reaction by 60MeV/u O-18 ions bombardment of natural uraniu m. Thorium was radiochemically separated from the mixture of uranium and re action products. Pa-238 as a daughter nucleus of 238Th has been identified according to the growth and decay of Pa-238 gamma rays which has been obser ved. The half-life of Th-238 was determined to be (9.4 +/- 2.0) min. At the same time, a new gamma ray of (89.0 +/- 0.3) keV with T-1/2 = (8.9 +/- 1.5 ) min was found in the gamma spectrum gated with the K-alpha 1 X ray of Pa and assigned to Th-238 decay based on the measurements of its transition en ergy and the half-life.