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One of the key components of radiopharmaceuticals for targeting imaging and therapy is a stable bifunctional chelating system to attach radionuclides to selective delivery systems. After-effects of radioactive decay can cause the release of a radioactive isotope from its chelation agent. Perturbed angular correlation (PAC) of γ-rays has become a unique technique to study the behavior of complexes formed between a chelating agent and radionuclide in vivo (in real time) over a relevant range of concentrations (10-12 M). In the present work, four radionuclides, 111In, 111mCd, and 152, 154Eu, were investigated with diethylenetriaminepentaacetic acid (DTPA) at different pH values to determine the stability constants of the complexes as well as the effects of post-decay processes, which play a major role in determining the suitability of these complexes for application as radiopharmaceuticals (e.g., in vivo generators). The study provides a convenient parameter for the characterization of radionuclide-chelator systems using the PAC method. PAC is proven to be a suitable tool to study novel chelators and radiopharmaceutical precursors attached to radiometals.

A method for the production of 111In from an antimony target irradiated with 600 MeV protons has been developed. Here, a three-stage scheme of indium purification using ion-exchange chromatography is performed. The radiochemical yield is 85%, with a decontamination factor of the target material of no less than 109. The 111In preparation produced by the present method was used in studies of perturbed angular correlations. Also, a procedure for the production and separation of 117mSn/119mTe was developed, which is of particular interest for further studies on designing a generator to produce 119Sb.

The distribution coefficients of Hf(IV) and Lu(III) between Dowex 50W×8 cation exchanger or Dowex 1×8 anion exchanger and mixed HCl–H2C2O4 solutions and between Dowex 50W×8 cation exchanger or Dowex 1×8 anion exchanger and citric acid solutions were determined. A number of modifications of the 172Hf → 172Lu generator, based on reverse separation schemes, were examined. Systems consisting of an anion-exchange resin and a solution of appropriate organic acid were taken as a chemical basis of the generator. Irreversible sorption of 172Lu in generator columns was studied. The optimum operation mode of the 172Hf → 172Lu generator based on the reverse-tandem scheme with periodic transfer of the parent radionuclide into the liquid phase was determined.

The principal aspects of 44Ti application in time-differential γγ perturbed-angular-correlation method (TDPAC) for studying condensed matter are discussed. In the presented spectrometer modification, the efficiency of 44Ti application can be considerably increased by using thin NaI scintillator crystals. Promising techniques for 44Ti production and a method for synthesizing samples are described. Examples of TDPAC studies of titanium (rutile TiO2) and scandium (Sc2O3) oxide samples are shown.

International audience; AbstractA radiochemical method for producing 82Se sources with an ultra-low level of contamination of natural radionuclides (40K, decay products of 232Th and 238U) has been developed based on cation-exchange chromatographic purification with reverse removal of impurities. It includes chromatographic separation (purification), reduction, conditioning (which includes decantation, centrifugation, washing, grinding, and drying), and 82Se foil production. The conditioning stage, during which highly dispersed elemental selenium is obtained by the reduction of purified selenious acid (H2SeO3) with sulfur dioxide (SO2) represents the crucial step in the preparation of radiopure 82Se samples. The natural selenium (600 g) was first produced in this procedure in order to refine the method. The technique developed was then used to produce 2.5 kg of radiopure enriched selenium (82Se). The produced 82Se samples were wrapped in polyethylene (12 μm thick) and radionuclides present in the sample were analyzed with the BiPo-3 detector. The radiopurity of the plastic materials (chromatographic column material and polypropylene chemical vessels), which were used at all stages, was determined by instrumental neutron activation analysis. The radiopurity of the 82Se foils was checked by measurements with the BiPo-3 spectrometer, which confirmed the high purity of the final product. The measured contamination level for 208Tl was 8–54 μBq/kg, and for 214Bi the detection limit of 600 μBq/kg has been reached.

90Nb has an intermediate half-life of 14.6 h, a high positron branching of 53% and optimal β + emission energy of only E mean 0.35 MeV per decay. These favorable characteristics suggest it may be a potential candidate for application in immuno-PET. Our recent aim was to conduct studies on distribution coefficients for ZrIV and NbV in mixtures of HCl/H2O2 and HCl/oxalic acid for anion exchange resin (AG 1 × 8) and UTEVA resin to develop a “direct flow” separation strategy for 90Nb. The direct flow concept refers to a separation accomplished using a single eluent on multiple columns, effectively streamlining the separation process and increasing the time efficiency. Finally, we also demonstrated that this separation strategy is applicable to the production of the positron emitter 90Nb via the irradiation of molybdenum targets and isolation of 90Nb from the irradiated molybdenum target.

Summary A technique of selenium purification from 232Th, 238U, 226,228Ra, 227Ac and 40K was developed. This technique is simple to perform and employs a minimum number of highly pure reagents (bidistilled water, nitric acid). Operations carried out during purification (elution, evaporation) practically exclude losses of the target product (chemical yields of Se > 99%). A test purification of 100 g of selenium was carried out using this technique. The efficiency of this technique was confirmed by low background gamma spectrometry of the purified selenium sample. Distribution coefficients of Th, U, Ra and Ac on DOWEX 50W-×8 cation-exchange resin at different concentrations of selenium and nitric acid were experimentally determinated. Instrumental neutron activation analysis of bidistilled water, deionized water and nitric acid was performed.

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.

Using the method of laser-induced fluorescence in an atomic beam we have measured the hyperfine splitting constants, A and B, of the ground and excited states of the optical transition 4f 76s 2 8S $_{1/2}\to 4f^{7}$ 6s6p 6P5/2 (564.58 nm) for 151 − 155Eu isotopes. For all isotopes, the magnetic dipole constants of the 6P5/2 atomic level are determined to a precision better than 0.04%. The A and B constants for the ground state 8S7/2 of the radioactive 152,154,155Eu were obtained for the first time with a precision better than 0.5%. Our data along with previous ground state hyperfine structure measurements for the stable europium isotopes allow us to determine the hyperfine anomaly for mentioned Eu isotopes.

High-resolution laser spectroscopy measurements of optical hyperfine splitting on the 151, 152, 153Eu isotopes were performed on the atomic transition 4f76s28S7/2 → 4f76s6p6P5/2 at λ ≈ 564.58 nm. Values of the nuclear magnetic dipole and electric quadrupole moments are obtained from the measured hyperfine splitting and the magnetic hyperfine anomalies in the isotope pairs 151, 152Eu and 152, 153Eu are deduced. The absolute values of the hyperfine anomaly in both cases are unusually large: 5 (1)%. The possible sources causing these anomalies are discussed.

A laser spectroscopic setup has been applied in the past to successfully investigate off-line the hyperfine structure splitting of radionuclides. In the present paper, its modification is described which will enable the determination of nuclear magnetic dipole and electric quadrupole moments with higher sensitivity and higher resolution.

Hyperfine-splitting constants in the optical spectra of rare-earth elements, Nd, Eu, Gd, and Lu, were measured using the laser-induced resonance fluorescence in a low-divergence atomic beam. Values of the hyperfine magnetic anomaly for different atomic levels were determined by comparing the ratios of the magnetic dipole constants of neighboring isotopes with odd numbers of protons or neutrons. The relation of these values to the special features of the atomic and nuclear structure of the investigated elements is discussed.

The constants of the hyperfine splitting in the atomic optical spectra of the rare-earth elements - Nd, Eu, Gd and Lu - were measured. The method of laser resonance fluorescence in the parallel atomic beam was used. The values of the hyperfine magnetic anomaly were determined from the comparision of magnetic dipole constant ratios of the neighbouring odd Z or N isotopes for the different atomic levels. The connection of these values and the parameters of atomic and nuclear structure is discussed.

The necessity and importance of investigations of polarized nuclei is motivated and the possibilities of laser spectroscopy for obtaining nuclear polarization are discussed. Different experimental methods for application of laser radiation to polarization of fission fragments of heavy elements are proposed. These fragments cover ranges of nuclides very interesting from the point of view of the nuclear structure. Of especially interest are fission fragments near the shell closures N=50 and N=82 and at the boundary of the deformation regions. It is shown that the laser radiation could be effectively used for fission fragment polarization and experiments with polarized fragments could play a role as a new source of information about nuclides far off β-stability.

The study of the nuclear structure of fission fragments is discussed. They are neutronrich nuclei the structure of which posses some peculiarities. Two regions of fission fragments are discussed: near the shell closures N=50 and N=82 and at the boundary of the deformation. A view on the optical properties of these elements is presented and different laser spectroscopic methods for their investigation are proposed.

The hyperfine structure of the D2 optical line in 22Na and 23Na has been investigated using high resolution laser spectroscopy of a well-collimated atomic beam. The hyperfine splitting constants A and B for the excited 3p 2P3/2 level for both investigated sodium isotopes have been obtained. They are as follows: A(22) = 7.31(4) MHz, B(22) = 4.71(28) MHz, A(23) = 18.572(24) MHz, B(23) = 2.723(55) MHz. With this data, using the high precision MCHF calculations for the electric field gradient at the nucleus, the electric quadrupole moment of 22Na has been deduced: Qs(22) =+0.185(11) b. The sign of Qs(22), determined for the first time, indicates a prolate nuclear deformation. A precise value of the isotope shift 22,23Na in the D2 line has also been obtained.

An experimental setup is described for the measurement of optical atomic spectra using a beam of charged cyclotron particles. The setup consists of a gas chamber for collecting and transporting the products of nuclear reactions, an ionization spectrometer based on a pulsed Nd:YAG laser, and a system of electronic modules. The setup allows the investigation of nuclei at the limits of nucleonic stability.

Efficient frequency-doubling systems with a specific geometry configuration are used in order to obtain ultraviolet (UV) cw coherent radiation for laser spectroscopy of exotic radionuclides in the 30 ≤ Z ≥ 58 region. The compensation of the walk-off angle and the use of external cavity for second harmonic generation give most noticeable doubler efficiency increase. Three frequency-conversion systems are proposed for laser spectroscopy of nuclei. Second harmonic efficiency of 18% is obtained. Perspectives of using the injection seeded nonlinear converters in laser spectroscopy are also discussed.

The present paper aims to discuss the prospects for nuclear structure investigation of the transuranium elements by laser spectroscopy. The authors lay stress on two peculiarities of the nuclear structure in this region: The deformed shell closure at neutron number N = 152 and the appearance of superdeformed isomeric states. A laser spectroscopic experimental method is proposed to study these features.

High resolution spectra of LaI lines recorded in the R6G region by laser-induced resonance fluorescence method show well resolved hyperfine structures. The analysis of the hyperfine structure of seven LaI transitions is presented here. It has allowed the deduction of magnetic dipole and electric quadrupole constants of all levels belonging to the excited odd parity multiplets: 4Fo (J = 3/2-9/2), 2Po (J = 1/2,3/2), and 4So (J = 3/2). Some of the results are new and some of them present improved values of the hyperfine splitting constants.