Scintillators Based on Ytterbium Chloride Adducts with Neutral Organophosphorus Extractants for Detecting Solar Neutrino for LENS (Low-Energy Neutrino Spectroscopy) Experiment

The main features of extraction of ytterbium chloride with dibutyl butylphosphonate (DBBP) and triisoamylphosphine oxide (TIAPO) were studied. The effects of temperature, DBBP and TIAPO concentrations in 1,2,4-trimethylbenzene (TMB), and concentrations of salting-out agents LiCl and NH₄Cl and mineral acid (HCl) on the ytterbium distribution coefficient were determined. The isotherms of extraction of HCl and YbCl₃ with 50% DBBP and TIAPO in TMB were obtained. The composition of the extractable complexes of ytterbium chloride with DBBP and TIAPO (S), YbCl₃·3S, was determined by saturation and dilution methods. The saturation of 50% solutions of DBBP and TIAPO in TMB with ytterbium chloride was modeled. Two samples of scintillators with ytterbium concentration of 90 g l^{- 1} were prepared, and their physical parameters were measured. The stability of sample properties was tested for 18 months.     

Extraction of scandium from various media with triisoamyl phosphate: 3. Development of extractive refining of scandium

Scandium refining to remove both more and less extractable impurity metals from hydrochloric acid solutions using semicountercurrent and countercurrent extraction with triisoamyl phosphate is modeled. A process for preparing high-purity scandium is developed, involving removal of more and less extractable impurity metals by semicountercurrent extraction and full countercurrent extraction, respectively, at a limited number of separation steps. From the initial scandium oxide (98% purity), 99.97% scandium oxide was prepared (99.995% purity with respect to REEs), i.e., the decontamination factors from both REEs and other impurity metals exceed 100.     

Determination of effective recombination coefficient by thermodesorption method

The degassing by thermodesorption method (TDS) of structural material sample previously hydrogen saturated is considered. The mathematical model of TDS-experiment and parametric identification method are presented. The data for nickel and tungsten in numerical simulations are used. The two-peak problem and effect (“derivatives”) of diffusion and desorption parameters on the TDS-spectrum are illustrated. Diffusion coefficient is known but the recombination parameters on surface remain to be estimate. The estimation algorithm needs no special mathematical software and allows to scan a material in wide temperature range. Integral smoothing processing of measurements is applied in the algorithm to secure its noise resistance.     

Extraction methods in development of Gd-loaded liquid scintillators for detection of low-energy antineutrino: 1. gadolinium extraction with carboxylic acids

A comparison was made of the properties of solvents meeting the requirements posed on Gd-loaded organic liquid scintillators (transparency, light output, compatibility with the structural materials of the detector). The optical properties of the solvents were examined in relation to various factors (purity of the initial reagents, concentrations of Gd and scintillation additives). Extraction of Gd with C₄ C₈ carboxylic acids was examined. The composition of the extractable Gd complexes with 2-methylvaleric and 2-ethylhexanoic acids, GdR₃·3HR·mH₂O (where m = 1–2, depending on the solvents used), was determined. The solubility of water in 2-ethylhexanoic and 2-methylvaleric acids was examined. Scintillators based on Gd 2-methylvalerates have better parameters than those based on the other carboxylic acids tested. The instability of the optical properties of the Gd carboxylate solutions is presumably due to the presence of water in the scintillator. Possible methods of water removal from the organic phase were discussed.     

Extraction of Sc from various media with triisoamyl phosphate: 2. Extraction of Sc from aqueous perchloric and hydrochloric acid solutions

The extraction of Sc from aqueous perchloric and hydrochloric acid solutions with triisoamyl phosphate (TIAP) was studied. The stoichiometry of the extractable complexes (ScA₃ · 3TIAP, A = ClO^4/? and Cl^?) was determined by the saturation and dilution technique. The isotherms of extraction of Sc from aqueous HClO₄ and HCl solutions were obtained. The extraction of impurity metals (Zn, Fe, Mo, Zr, Th, REE) was studied over wide HClO₄ and HCl concentration ranges.