Isao Tomita

Nuclear levels of 56Co from the decay of 56Ni

Abstract The decay of 56Ni is investigated to study lower excited states in the 56Co nucleus. From measurements of internal conversion electrons and angular-correlation functions for all coincident gamma-ray pairs, unique spin and parity assignments are obtained as follows: 163 keV level, 3+; 975 keV level, 2+; 1.45 MeV level, 1(2)−; 1.72 MeV level, 1+. Multipole mixtures of transitions between these levels are also determined. Results are discussed on the basis of the jj coupling shell model with p-n interactions.

Preparation and some properties of chromium phosphate ion exchanger

Abstract Two types of chromium phosphate ion exchanger have been prepared. One has low affinities for multivalent metal ions, another has high affinities. Distribution coefficients and their temperature dependence were measured for Na + , K + , Rb + , Cs + , Mg 2+ , Ca 2+ , Ba 2+ , Co 2+ , Zn 2+ and Ce 3+ ions. Ion-exchange capacities and thermostability in water were also examined. The pH titration curves show that these exchangers are polyfunctional for Na + and Cs + , but behave monofunctionally for Ba 2+ . The ion-exchange properties are strongly influenced by preparation conditions, e.g. mixing ratio of the materials, drying conditions, storage conditions and heating conditions.

Ion exchange behavior of alkali metal ions on crystalline zirconium arsenate

Abstract Forward and reverse exchange of hydrogen-alkali metal ions (Li + , Na + and K + ) was investigated on crystalline zirconium arsenate prepared by refluxing the gel in a mixture of HNO 3 and H 3 AsO 4 . Each of forward titration curves had two distinct regions and selectivity sequences were K + > Na + > Li + for the first stage and Na + ≈ Li + > K + for the second stage of exchange. X-ray powder patterns suggested the presence of a half exchanged phase and a fully exchanged phase. In the backward titration, the curves did not show any remarkable pH jump at half exchange. IR spectra of α-ZA and partly metal-ion exchanged phases suggested the presence of two OH groups with different acidity.

The Isotope Effect in the Electromigration of Sodium-Ion in Fused Sodium Nitrate

The isotope effect of sodium-ion in countercurrent electromigration (Klemms method) has been investigated for a system of fused sodium nitrate labelled with the radioactive nuclide 22Na. Two runs were made (Experiments A and B, respectively). In Experiment A, the fused salt chain, Al(cathode)-NaNO3-Pt(anode) was electrolyzed for 20 hr at 340 ?? with a current density of 1.3 A/cm2 in the separating tube. In Experiment B, electrolysis was carried out for 67 hr at 380 ?? with a current density of 1.5 A/cm2 in the separating tube. After electromigration, a change was observed in the specific activity of sodium in the separating tube. The elementary process separation factor, defined as the ratio of the mobilities of the isotopic ions, i.e., VNa-22/VNa-23, was calculated to be 1.0023 for Experiment A and 1.0017 for B. The mass effect for sodium ion in fused sodium nitrate was calculated to be -0.045±0.006 (standard deviation).

Enrichment of 7Li by countercurrent electromigration of molten lithium nitrate

Abstract Lithium-7 has been enriched from the natural abundance 92·58 to 99·94% (maximum) by countercurrent electromigration of molten lithium nitrate. In order to realize high enrichment in a short time, fine packing material of quartz (≯ 150 mesh) has been used. Both cylindrical and pseudotruncated cone shaped separation tubes have been used and the latter are found to be more efficient for rapid enrichment. In both cases the distribution of the salt at a stationary state can be expressed approximately in terms of a truncated cone shaped distribution. The most favorable conditions for high enrichment are discussed regarding the temperature, the grain size of the packing material and so forth.