178m2Hf isomer production cross-sections were measured when natural tantalum targets were irradiated by alpha particles in the energy range of 36-92 MeV. The simulations of these cross-sections in the TALYS-1.4 code showed that the main contribution to the 178m2Hf isomer production is given by (α, αp2n), (α, 3p4n) and (α, 3Hep3n) nuclear reactions. In the range of α-particle energies of 58-92 MeV, the theoretical results coincided well with the experimental ones, and based on this, the cross-sections of the 178gHf ground state production were estimated. allowing to calculate the isomer ratios as well. The obtained values are in good agreement with the trend of changes for the isomer ratios obtained in the nuclear reactions with lower-energy alpha particles and other targets.

178m2Hf isomer triggering was studied using the new experimental setup developed at the Kharkiv National University and installed at the Kyiv Institute for Nuclear Research. The target presenting a single Ta foil of 300 μm thickness with the 178m2Hf isomer activity of 100 Bq was irradiated by 30 keV electron beam. The enhanced counting rates of all strongest ground-state band (with the energies of 213, 325 and 426 keV) and 8−-state band (with the energies of 216, 495 and 574 keV) transitions from the 178m2Hf isomer decay were observed. Our data are consistent with the total triggering effect of 1.55±0.12%. An estimate for the photon induced triggering cross-section gives a value which is close to the upper limit obtained in the earlier published works on the 178m2Hf isomer triggering.

The influence of irradiations (reactor neutrons, 3 MeV protons and Ar+ ions with the energy of 125 keV) upon ferrite YIG films and devices properties has been investigated. Qualititative similarity of such influence for neutrons and protons has been established. Because of the homogeneous distribution of radiation defects in both cases, there is a simultaneous broadening of homogeneous FMR linewidth, magnetostatic oscillations and modes, and short dipole-exchange spin waves. In the case of Ar+ irradiation due to small path length, there is an inhomogeneous nanostructuring over the thickness of the film with characteristic layer size ~0.1 μm. The presence of nanolayers influences in the different way upon the properties of different film oscillations and modes. The decrease of FMR linewidth by 40% at the fluence of 3 × 1016cm−2 has been observed for the first time. At the same time, spin wave linewidth has practically not changed allowing to increase the efficiency of wave front reversal in YIG films irradiated by Ar+ ions. All discovered experimental facts are explained in the frame of multilayer model of the film consisting of alternate magnetic and nonmagnetic layers.

Oscillations and waves of magnetization in YIG ferrite films have interesting and useful properties such as a high Q-factor, a wide variety of dispersion laws dependent on the orientation of bias magnetic fields, and a possibility to tune their frequencies in the range of several GHz by changing the magnitude of bias magnetic fields. At the same time, YIG ferrite films are widely used in different electronic devices and equipment that have already found a variety of both space and nuclear applications. So radiation stability investigations of such materials became very important. Ferrite YIG films were irradiated by reactor neutrons, 3 MeV protons and deuterons, and electrons with the energy up to 20 MeV to the fluences 1.8 x 10(19) n/cm(2), 9.6 x 10(15) p/cm(2), 1.1 x 10(16) d/cm(2) and 6.6 x 10(17) e/cm(2), respectively. The radiation effects have been analyzed using the ferromagnetic resonance method. The results of such radiation stability study show clearly that ferrite YIG films, just as devices and equipment based on them, have a long operation life and very high radiation stability. At the same time, parameters and properties of YIG films and microwave ferrite devices that use such films can be changed controllably and, moreover, more reliably than using the traditional grinding. (C) 2007 Ellsevier B.V. All rights reserved.

Hf-178m2 isomer production in different spallation reactions with protons, alpha particles and neutrons at projectile energies up to 100 MeV has been analyzed using both STAPRE and ALICE code simulations. The STAPRE code was used to calculate the isomeric ratios, while the ALICE code was used to simulate the excitation functions of the respective ground states. A number of spallation reactions have been compared taking 4 into account not only Hf-178m2 isomer productivity but also, first, the isomeric ratios calculated by the STAPRE code; second, the accumulation of the most undesirable Hf isotopes and isomers, such as Hf-172, Hf-175, and Hf-179; and, third, the production of other admixtures and by-products that could degrade the quality of the produced Hf-118m2 isomer sources, including all stable Hf isotopes as well. Possibilities and ways of optimizing Hf-178m2 isomer production in spallation reactions at projectile energies up to 100 MeV are discussed. This can be considered a very important preliminary stage for accumulating such exotic nuclear isomers in lab-sized quantities at reasonable cost.