The paper describes the solvent extraction of trace thorium from hydrochloric acid media by1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) using a radioactive tracer technique. The percent extraction ofthorium was studied as a function of acidity, PMBP concentration and equilibrium time. The back-extraction behaviorof thorium from the organic phase was also tested. Separation of thorium was performed from fission products pro-duced in 14 MeV neutron bombardment of natural uranium by employing the PMBP extraction procedure. Thegamma-ray spectra of the separated thorium fractions show that thorium can be separated from most of fission prod-ucts and a large amount of uranium.
YANG Wei-Fan, YUAN Shuang-Gui, XU Yan-Bing, XIAO Yong-Hou, XIONG Bing (Institute of Modern Physics, the Chinese Academy of Sciences, Lanzhou 730000)
Thick gold targets were bombarded with 47 MeV/nucleon C ions and the radioactive isotopes of iridium 12 and platinum were produced through the multi-nucleon transfer reactions. The production cross-sections of iridium isotopes in the reactions have been determined by a combination of radiochemical separation and off-line γ-ray spec- troscopy technique. The obtained Ir isotope distribution was compared with those obtained in other experiment as well as calculated by the statistical model.
MeV/u 18O ions were used to bombard natural uranium targets, and the heavy neutron-rich isotope 237Th was produced via multi-nucleon transfer reaction and dissipative fragmentation of the heavy target. A relatively fast radiochemical procedure was used to separate thorium from the mixture of uranium and complex reaction products. The chemically separated thorium fractions were studied by the 7-ray spectroscopic method. The behaviors of the growth and decay of 853.7 and 865.0 keV-γrays of 237Pa decay were observed. The half-life of 237Th was determined to be 4.69±0.60 nun.
230Pa was produced through the 232Th(p,3n)230Pa reaction in the irradiated ThO2 powder targets with 35 MeV proton beam. Pa was radiochemically separated from ThO2 and other reaction products, and then thin sources of 230Paβ-230U were prepared. The polyethylene-terephthalate (lavsan) films were selected as solid track detector searching for the cluster activity of 230U. The gamma activity of 230Pa in the sources was measured using a HPGe detector. The lavsan films were etched in NaOH solution and the etched films were scanned under an optical microscope. The exotic nuclear decay of 230U by emission of 22Ne was observed. A branching ratio relative to α decay was deduced, B =λNe/λα= (1.3±0.8)×10-14 for 22Ne emission from 230U.
The activities of protactinium were produced by the multi-nucleontransfer reactions in bombardment of the natural uranium with 60 MeV/nucleon 1sOions. A simple, relatively fast radiochemical procedure was used for extraction sep-aration of protactinium from the uranium and a variety of reaction products using1-phenyl-3-methyl-4-benzoyl-5-pyrazolone and tri-iso-octylamine as extractants. Theγ ray spectrum of the separated protactinium fractions showed that the protactiniumcould be separated from all of the main impurity elements. The decontaminationfactors of the uranium and the main reaction products produced in the reaction aregiven.
YANG Wei-Fan, YUAN Shuang-Gui, XIAO Yong-Hou, XU Yan-Bing, FANG Ke-Ming (Institute of Modern Physics, the Chinese Academy of Sciences, Lanzhou 730000)
