Search

Abstract: A rapid radiochemical separation procedure has been finished by using of radiochemical separation and gamma-spectrum measurement methods. In this isolation procedure, tantalum nuclides produced by the irradiation of natural tungsten targets with 14 MeV neutrons were extracted by methyl isobutyl ketone (MIBK) in the system of HF-HNO3 mixed solutions. It has been found that tantalum was rapidly and efficiently separated in the isolation procedure and the decontamination factors of tungsten were more than 104. The procedure is simultaneously used to separate tantalum from tungsten bombarded with intermediate energy (47 MeV/u)18O beams. The measured gamma-spectra showed that tantalum can be separated from most elements produced in the nuclear reactions except for a few elements.

Abstract: A new heavy neutron-rich thorium isotope was produced via a multinucleon transfer reaction by irradiation of natural uranium targets with 60 MeV/u18O ions. The Th activities was radiochemically separated from the uranium and mixture of reaction products by the rapid solvent extraction method. Measurements of the gamma-ray spectra were performed with HPGe detectors. The new neutron-rich isotope238Th was identified for the first time based on the observation of the growth and decay of the gamma-ray with energy of 1060.5 keV from the decay of238Pa. The half-life of238Th has been determined to be 9.4±2.0 minutes. Further, a gamma-ray of 89.0 keV with the 8.9-minute half-life was found, which may be due to the decay of the new isotope238Th.

A 1.2±0.3 min activity produced with 14-MeV neutrons using the reaction176Yb(n,2p)175Er has been assigned to β− decay of the unreported erbium isotope175Er. A partial decay scheme is proposed based on X-γ and γ-γ coincidence measurements.