The targets with masses in range of 51-207 a.u. have been exposed to the bremsstrahlung photon beam of the electron linear accelerator of AANL (Yerevan Physics Institute). Yields of (gamma, alpha), (gamma, alpha xn) and (gamma, xpyn) reactions have been measured at the maximum bremsstrahlung photon energy of 20, 30, 40 and 70 MeV. The yields and the flux-weighted average cross sections of a number of the reactions were compared with the results of calculation in the frames of the TALYS-1.9 model. Agreement between the calculated and experimental data was obtained within a factor of two.

Experimental data on production of radioactive residuals in11B +209 Bi reaction a above-barrier projectile energy of 145.6 MeV are presented. The measurements and identification of reaction products were made using the method of induced activity. The residual nuclei in 24 < A < 211 mass range are considered as products of different interaction channels, occurring through evaporation at complete, incomplete fusion and the fission. The fragments in (60-160) atomic mass units range are regarded to the fission products and are confirmed with data from experiments with analogous fissile nuclei. The residual nuclei near target mass number can be presented as result of the different processes including emission of nucleons and light nuclei. Theoretical predictions within the frameworks of PACE-4 code simulation, allowing the predictions of formation, evaporation and fission of compound nuclei, were used for analyzing the measurement results. A substantial contribution to production of residual nuclei of the incomplete fusion and of additional mechanisms, proceeding at different impact parameters, were revealed at analysis of the experimental data.

The production of alpha particles in photonuclear reactions on 65Cu, 115In, 92Mo and 207Pb targets in the beam of accelerated electrons with energy of 21 and 40 MeV was studied. The experiments were run on the Linear Electron Accelerator NLA (The Yerevan Physics Institute). The measurement results represent the yields of reactions studied as functions of the mass number of nuclei and the photon energy. The data obtained enable one to suggest a change in the mechanism of alpha particle photoproduction with increasing energy of incident photons and target mass.

The process of photoproduction of a series of radioisotopes from copper nuclei at the bremsstrahlung end-point energies $$E_{\gamma }^{{\max }}$$ = 21, 30, and 40 MeV was studied at the AANL (YerPhI) linear electron accelerator. The relative yields of 61Co, 60Co, 58Co, 57Co with respect to the 61Cu are measured; in particular, at $$E_{\gamma }^{{\max }}$$ = 40 MeV they are equal to (2.6 ± 0.3) × 10–2, (2.67 ± 0.04) × 10–2, (9.3 ± 0.6) × 10–2, and (0.76 ± 0.04) × 10–2, respectively. It is shown that the predictions of the TALYS model, as well as the model inserted in the GEANT4 software package are in a contradiction (especially in the case of the GEANT4 code) with the measured relative yields. A continuously decreasing energy dependence was observed for the ratio of unfolded (weighted with the bremsstrahlung spectrum) cross-sections of reactions 65Cu(γ,α)61Co and 63Cu (γ,2n)61Cu, similarly to that observed earlier for the ratio of cross-sections of electronuclear reactions 65Cu(e,e′ + α)61Co and 63Cu (e, e′ + 2n)61Cu. The ratio of the 61Co and 64Cu yields is also measured, being equal to (2. 6± 0.2)×10–3, (3.8 ± 0.6) × 10–3, and (3.2 ± 0.4) × 10–3, respectively, at $$E_{\gamma }^{{\max }}$$ = 21 MeV, 30 MeV, and 40 MeV; its value (2.6 ± 0.2) × 10–3 at $$E_{\gamma }^{{\max }}$$ = 21 MeV is consistent with the general trend of the dependence of this ratio on the atomic number Z, measured recently at $$E_{\gamma }^{{\max }}$$ = 23 MeV for heavier nuclei with the atomic numbers from Z = 47 to Z = 82.

Independent and cumulative production cross sections for radioactive nuclear fragments from the deuteron-irradiation of isotopically enriched lead (Pb-204, (206)pb, Pb-207, and Pb-208) targets were obtained for the first time. The experiment has been performed with a 4.4 GeV deuteron beam from the Nuclotron of the Laboratory of High Energy Physics (LHE), Joint Institute for Nuclear Research (JINR) at Dubna. The production cross sections of target fragments were determined by off-line 7-ray spectroscopy. Charge dispersion and massyield distributions were deduced from these data. The results are discussed in terms of the relative importance of different reaction mechanisms (evaporation-spallation, fission and multifragmentation). Comparison of our results with the data from the reaction induced by protons of about the same kinetic energy per nucleon, has been performed. The coexistence of the different decay modes in the formation of the reaction residues, such as spallation, fission and multifragmentation is suggested.

Experimental data on production of radioactive residuals in 11B +209 Bi reaction a above-barrier projectile energy of 145.6 MeV are presented. The measurements and identification of reaction products were made using the method of induced activity. The residual nuclei in 24 ≤ A ≤ 211 mass range are considered as products of different interaction channels, occurring through evaporation at complete, incomplete fusion and the fission. The fragments in (60-160) atomic mass units range are regarded to the fission products and are confirmed with data from experiments with analogous fissile nuclei. The residual nuclei near target mass number can be presented as result of the different processes including emission of nucleons and light nuclei. Theoretical predictions within the frameworks of PACE-4 code simulation, allowing the predictions of formation, evaporation and fission of compound nuclei, were used for analyzing the measurement results. A substantial contribution to production of residual nuclei of the incomplete fusion and of additional mechanisms, proceeding at different impact parameters, were revealed at analysis of the experimental data.

The isoscaling behavior of the fragment production cross section was studied for reactions with deuterons on enriched lead targets ( 204 Pb, 206 Pb, 207 Pb, 208 Pb). The information about the reaction mechanism as well as the origin of the residues in the mass range 20 ≤ A ≤ 100 were obtained. During the analysis it was found the same behavior of the reactionmechanism as in the reactions with deuteron on enriched tin isotopes ( 112 Sn, 118 Sn, 120 Sn, 124 Sn). In the present article the estimation of the temperature and the symmetry energy coefficient of composite systems was done.

Residual nuclei formed at ground and isomeric states from the interaction of 4.4 GeV deuteron with a gold target have been measured and investigated by the induced-activity method. Eight isomeric and ground-state pairs of target residues in the mass range of 44 < A < 198 were identified by off-line gamma-spectroscopy analysis and their isomer ratios were obtained from the cross-section production. From the isomer ratio data of the formed Au-196 and Hg-197 nuclei, the average intrinsic angular momentum of the composite system was estimated by means of a simple statistical model based on the formalism developed by Huizenga and Vandenbosch.

Mechanism of nuclear reactions on 197Au induced by 11B ions at energies above Coulomb barrier was studied by induced-activity method and gamma-spectroscopy. The cross sections of the reaction fragments from 197Au induced by 11B ions were measured at bombarding energies 137.5 and 255.5 MeV. The fission process was investigated by using multimodal fission approach at the energy 137.5 MeV, and pure symmetric distribution at 255.5 MeV. It was observed that the transferred linear momentum provides the information on the initial projectile-target information. The fissility for both fission reactions under study was deduced from measured fission cross section using the total inelastic cross section. Comparison with proton-induced fission shown, that the linear momentum transferred to the fissile system depends on the probe.

In this work, we present new experimental data on mass distribution of fission fragments from $^{241}$Am proton-induced fission at $660$ MeV measured at the LNR Phasotron (JINR). The systematic analysis of several measured fragment mass distributions from different fission reactions available in the literature is also presented. The proton-induced fission of $^{241}$Am, $^{237}$Np and $^{238}$U at 26.5, 62.9 and 660 MeV was studied. The proton-induced fission of $^{232}$Th was studied at 26.5, 62.9 and 190 MeV. The fission of $^{208}$Pb also by a proton was investigated at 190, 500 and 1000 MeV. The fission of $^{197}$Au was studied for 190 and 800 MeV protons. Bremsstrahlung reactions with maximum photon energies of 50 and 3500 MeV were studied for $^{232}$Th and $^{238}$U. The framework of the Random Neck Rupture Model was applied in the analysis. The roles of the neutron excess and of the so called fissility parameter were also investigated.

Production cross sections for nuclei fragments from the interaction of B-11 ions with Bi-209 and Ta-181 targets, in the intermediate energy regime, have been obtained with the induced-activity method and offline gamma spectroscopy. The mass-yield distributions were obtained and the fission process was investigated by using the multimodal fission approach in the case of the Bi-209 target and a pure symmetric distribution for the Ta-181 target. The fissilities were deduced for both targets and further compared to the data for proton-induced reactions. The relative values of the linear momentum imparted to the targets were derived from the cross section data.

The cross sections for the binary fission of 197Au, 181Ta and 209Bi targets induced by 11B ions were measured at intermediate energies. The fission products cross sections were studied by means of activation analysis in off-line regime observed gamma-ray spectra. The fission cross section is reconstructed on the basis of charge and mass distribution of the fission products.

A study of photofission on $^{181}\mathrm{Ta}$ induced by bremsstrahlung with endpoint energies of 50 and 3500 MeV has been performed. The fission yields have been measured by using the induced-activity method in an off-line analysis. The total photofission yields for the tantalum target at 50 and 3500 MeV are found to be $5.4\ifmmode\pm\else\textpm\fi{}1.1 \ensuremath{\mu}\mathrm{b}$/ equivalent quanta per second (eq.q) and $0.77\ifmmode\pm\else\textpm\fi{}0.11$ mb/eq.q, respectively, and the corresponding deduced fissilities are $(0.23\ifmmode\pm\else\textpm\fi{}0.05)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ and $(2.9\ifmmode\pm\else\textpm\fi{}0.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. Mass- and charge-yield distributions were derived from the data. The results were compared with the simulated results from the crisp code for multimodal fission by the assuming symmetrical fission mode.

The independent cross section ratio for production of nuclei from 197Au targets irradiated with 4 GeV deuterons have been measured by off-line gamma-spectroscopy. On the basis of the measured independent cross section ratio of 198m, gAu the average intrinsic angular momentum of the primary nucleus was estimated by means of a simple statistical-model analysis based on the formalism developed by Huizenga and Vandenbosch.

A comprehensive set of 110 radioactive nuclide cross sections with mass numbers 22 ≤ A ≤ 198 amu in the interaction of 4.4-GeV deuterons with 197Au have been measured for the first time. The results including charge distributions have been parameterized in term of a 3-parameter equation in order to reproduces the isobaric distributions. Using data from the charge distributions, the total mass-yield distribution was obtained. The new experimental data of the recoil properties of reaction products were also obtained. Kinematical characteristics of the reaction products obtained from measurements of the residuals emitted in the forward and backward directions exhibit different behavior depending on the mass region. The kinematical features of reaction products have been analyzed on the basis of the two-step model of high-energy nuclear reactions and discussed in terms of the different reaction mechanisms.

The production cross sections for 110 radioactive nuclides, with mass numbers 22 <= A <= 198, were obtained from the interaction of 4.4 GeV deuteron with a Au-197 target using the induced-activity method. The deuteron beam was obtained from the Nuclotron of the Laboratory of High Energies (LHE), Joint Institute for Nuclear Research (JINR) at Dubna. Using the charge distribution data, we derived the total mass-yield distribution. The analysis of the mass-yield distribution allowed us to consider the coexistence of different channels in the interaction such as evaporation, fission, and multifragmentation.