A four-detector spectrometer of perturbed angular γγ correlations is developed for investigation of hyperfine interactions in condensed matter. It allows measurements with practically any type of detectors. A unique circuit design involving a specially developed Master PAC unit combined with a computer allows a substantially higher efficiency, reduced set-up time and simpler operation in comparison with traditional PAC spectrometers. A cryostat and a high-temperature oven allow measurements in the temperature range from 120 to 1300 K. An encased electromagnet makes it possible to generate a magnetic field up to 2 T on a sample. The measurement system includes a press with a specially designed high-pressure chamber allowing on-line PAC measurements in samples under pressure up to 60 GPa.

Yields and cross-sections of the radioactive nuclides produced after the irradiation of natural composition W and enriched 186W targets at the Dubna synchrocyclotron were measured using the γ-ray spectroscopy methods with high-resolution Ge detectors. Among the detected nuclides we identified the spallation and fission products. High-spin isomeric states in the Hf and Lu nuclides were populated and the isomer-to-ground state ratios could be estimated. The nuclide yields were calculated using the LAHET code at six different values of the proton energy in the range from 100 to 800MeV both for the natW and enriched 186W targets. The measured isotope yields are in general good agreement with the calculations. A shortcoming of the code is the inability to predict isomer-to-ground state ratios. The experimental data show that the 177mLu, 178m2Hf and 179m2Hf high-spin isomers are produced with a 2.5 times higher yield in the 97% enriched 186W target as compared to the natW target under identical irradiation conditions. This makes significance for the creation of high-activity isomeric sources. The mass-distribution of the products and the fission-to-spallation ratio were also deduced and compared with theory prediction.

The electrophoretic behavior of the 111In-DTPA radiopharmaceutical has been investigated. The stability constant, diffusion coefficient and effective charge of the complex as well as the temperature dependence of the electrophoretic mobility were determined. No-carrier-added 111In with high specific activity was used in the electrophoretic experiments in ultramicroconcentrations (10(-9)M).

The productivity of the spallation reactions at proton energies of 100–660MeV for accumulation of the radioactive isotopes and isomers has been studied experimentally. Spectra of Ta and Re targets activated at Dubna synchrocyclotron were measured using the methods of radiochemistry and gamma spectroscopy. Many radioactive products of the spallation and fission reactions are identified, and their yields are compared with the LAHET code simulations. Cross-sections σm and isomer-to-ground state ratios σm/σg are deduced for nuclear isomers, in particular, for high-spin isomers, as 178m2Hf, 179m2Hf and 177mLu. Spin distributions for the spallation-residue nuclei are estimated to understand the σm/σg ratios. Possibilities to optimize the methods for the long-lived isomers production are discussed, and it would be a necessary step on the way to accumulate such exotic radionuclides in milligram amount under reasonable cost and radiation safety conditions.

A new method of the perturbed angular gamma-gamma-correlation (PAC) measurements was developed using one HPGe detector only (1-PAC). For quantifying the perturbation factor, the ratio R gamma 1 + gamma 2 of the summing peak composed of two cascade gamma-rays (the perturbation-affected parameter) to the summing peak composed of one gamma-ray and one X-ray (the perturbation non-affected parameter) was used. This method was demonstrated for the radionuclides 111In and 111mCd, identifying the chemical status of the radionuclides in aqueous solutions.

New types of element-loaded (B and Gd) organic scintillators for neutron detection and neutrino experiments have been synthesised recently in the JINR. Their optical, spectral, scintillation and radiopurity characteristics are presented and discussed. It is shown that 5% B-loaded plastic scintillator has a light output as much as 70% relative to the unloaded one. The same characteristic for the 3% Gd-loaded plastic sample is equal to 51%. Transparency and other properties of the produced scintillators did not changed at normal conditions for at least one year.

We report the high-pressure synthesis of novel superconductor MgB2 and some related compounds. The superconducting transition temperature of our samples of MgB2 is found to be 36.6 K. The MgB2 lattice parameters determined via X-ray diffraction are in excellent agreement with results of our ab initio calculations. The TDPAC measurements of 111Cd quadrupole frequency νQ demonstrate a small increase in νQ with decreasing temperature from Troom to THe. The electric field gradient Vzz at the B site calculated from first principles is in fair agreement with Vzz obtained from 11B NMR spectra of MgB2 reported in the literature. It is also very close to Vzz found in our 111Cd TDPAC experiments, which suggests that the 111Cd probe substitutes for boron in the MgB2 lattice.

111Cd–PAC measurements have been made using the high specific activity of 111In in the methanol–water mixtures of various concentrations at the room temperature. These experiments revealed that the perturbation factors 〈A 2 G 2〉 (integrated over two mean lives τN) do not follow the dependence of the macroscopic viscosity η. The observed dynamic character of the PAC spectra in ice is explained by the mobility of orientational and ionic defects. The activation energy for the diffusion process was determined to be E a =0.35(1) eV.

A new method of 111In separation from a silver target irradiated with 30 MeV alpha-particles is described. The 111In isolation from Ag and Cd is based on its co-precipitation with La(OH)3. The 111In separation from La(III) has been performed by the method of ion-exchange chromatography. A multi-stage purification technique was developed that allows the production of 111In radiochemicals in which the part of impurities of di-, tri-valent metal atoms is negligible.

Time-differential PAC measurements have been made using the high specific activity of 111In, both in aqueous solutions of the ClO- 4 , NO- 3 and Cl- at pH values between 1.0 and 9 and temperatures between 186 and 293 K.