Yu. V. Norseev

High-sensitivity delayed-coincidence spectrometer to search for short-lived nuclear states

A high-sensitivity four-dimensional triple-coincidence spectrometer with two detectors is developed on the basis of an autocorrelation single-crystal scintillation time 4π spectrometer and a semiconductor HPGe detector. The delayed-coincidence spectrometer is designed to search for isomeric nano- and micro-second states in short-lived nuclei and for their related γ-rays. Half-lives of short-lived states are measured in the range from 4 ns to 4 μs. The sufficient activity of the monoisotopic source for the investigations does not exceed 0.01 μCi.

Generator of actinium-225

Dependence upon pH of Ac and Th distribution coefficients between the cation exchange resin and buffer citrate solutions had been investigated; the optimal conditions are suggested for effective separation of the elements in this system. These results are in successful accordance with such conditions calculated on the basement of Ac and Th citrate complex formation constants.The generator method for225Ac periodical separation from229Th samples is developed.229Th storage in solution between separations excludes the contamination of actinium final solution with radiolysis products and provides 100-% yield of this isotope and its high radiochemical purity. The parent nuclide loss after continuous use of the generator does not take place.

Characterization of DTPA complexes and conjugated antibodies of astatine

The complex formation of astatine/I/ cation with diethylene triamine pentaacetic acid /DTPA/ and characterization of the complexes were investigated by electromigration in free electrolytes and by gel-chromatography on Sephadex G 25. We describe the conjugation procedure for the production of At-DTPA conjugated polyclonal antibodies.

Isolation of radionuclides from thorium targets irradiated with 300-MeV protons

Procedures were developed for isolation and separation of radionuclides from a thorium target irradiated with 300-MeV protons. A large set of radionuclides, including those of heavy elements (225,226Ac, 223,224,225Ra, 230U, 230Pa), were obtained. A perspective scheme was suggested for separation of radionuclides from irradiated thorium.

Negative pion capture in chemical compounds

Abstract The capture has been investigated of negative pions in LiI, NaI, KI, RbI and CsI. The capture probability is in agreement with the Z -law.

SYNTHESIS OF ASTATINE-TAGGED METHYLENE BLUE, A COMPOUND FOR FIGHTING MICROMETASTASES AND INDIVIDUAL CELLS OF MELANOMA

Investigation on electrophilic attaching of astatine-211 to methylene blue is carried out. Conditions for transferring astatine to a chemically active electrophilic form were found. A method for the production of astatine-211-tagged methylene blue has been developed. The resulting radiopharmaceutical preparation is free of the nonisotopic iodine carrier. The chromatographic method of purifying simultaneously the product by anion-exchange resin QAE-Sephades A-25 allows it to pass into a 0.9% solution of sodium chloride (physiological salt solution). The method provides the radiochemical yield of astatine-211-tagged methylene blue as large as 68±6%.

Low-energy transition depopulating the isomeric 8+ level in 208Po

Abstract Conversion electron measurements of the low-energy transition depopulating the isomeric 8+ level in 208Po yielded Eγ = 4025 ± 20 eV and the conversion intensity ratios N1/N2 ≲ 0.2, N2/N3 = 0.75 ± 0.10, N4.5/N3 ≲ 0.2, O/N3 = 0.35 ± 0.10, P/N3 ≲ 0.1 and N3/M3 = 0.4 ± 0.2. These ratios are in accord with our calculations for the E2 multipolarity and exclude all other multipolarities with L ≦ 4. The total conversion coefficient was calculated to be 1.31 × 107.

The predicted 10.6 keV transition in 221Fr from the α-decay of 225Ac revealed

The low energy electron spectrum from the α-decay of 225Ac has been measured with 20 eV instrumental resolution using an electrostatic spectrometer and radioactive sources prepared by vacuum evaporation. The predicted 10.642(5) keV M1 + < 0.05% E2 nuclear transition in 221Fr have been revealed. Energies of 26.015(5), 36.660(5), 38.543(3) and 108.37(1) keV nuclear transitions in 221Fr have been essentially improved. Relative intensities of the measured conversion electron lines of these transitions have also been determined.

211At-Rh(16-S4-diol) as a starting complex for preparing an astatine-labeled radiopharmaceutical

A new procedure for preparing an 211At-labeled radiopharmaceutical is suggested. The 211At− anion forms a strong bond with the Rh3+ cation incorporated in the complex with a thiother ligand, 1,5,9,13-tetrathiacyclohexadecane-3,11-diol (16-S4-diol). The reaction conditions are optimized with 131I as astatine analog. The complexes are studied by paper electrophoresis, ion exchange, and thin-layer chromatography. The kinetics of the addition of the 131I− anion to Rh(16-S4-diol) and the dependence of the yield of the forming complex 131I-Rh(16-S4-diol) on the temperature, solution acidity, and reactant concentrations are examined. Taking into account the results obtained, the complex 211At-Rh(16-S4-diol) is prepared by adding astatide (211 At−) to equivalent amounts of RhCl3 and the tetrathioether (16-S4-diol). the behavior of the astatine complex is studied.