Possibility of implementing a nondirect experiment aimed at determining the cross section for nucleon interaction with an excited nucleusSukhovoj, A. M.;Khitrov, V. A.
doi: 10.1134/s1063778810100017pmid: N/A
Abstract With the aid of experimental data on the level densities in the even-odd tungsten isotopes 183,185,187W as determined in the respective (n, 2ρ) reactions, the ratio of the cross section for the interaction of an excited nucleus with a neutron to its counterpart calculated on the basis of the optical model of the nucleus was obtained from the spectra of evaporated neutrons in the reaction 181Ta(p, n)181W. A significant local increase in this ratio is qualitatively interpreted as that which is due to the possible increase in the penetrability of the nuclear surface for nucleon reaction products because of the effect of phonon-type excitations. Sources of possible nonstandard systematic errors in experimentally determining the level density in an arbitrary nucleus at energies below the nucleon binding energy B n are analyzed. The extraction of information from the distribution of the intensities of cascades belonging to the nucleon and photon type is simulated. The resulting information may be highly reliable if use is made of the entire body of experimental data on the nucleus under analysis.
Cross section for 246 Cm subbarrier fissionAlekseev, A. A.;Bergman, A. A.;Berlev, A. I.;Koptelov, E. A.;Samylin, B. F.;Trufanov, A. M.;Fursov, B. I.;Shorin, V. S.
doi: 10.1134/s1063778810100029pmid: N/A
Abstract The cross section for 246Cm fission induced by neutrons of energy in the range 0.1 eV-20 keV was measured by the neutron lead slowing-down spectrometer (LSDS-100) of the Institute for Nuclear Research (INR, Russian Academy of Sciences, Moscow). The parameters of the resonance area and of the fission width were evaluated for several low-lying s-wave neutron resonances. The parameters of the intermediate structure in the cross section for the subbarrier fusion of 246Cm nuclei were found. The results obtained in this way were compared with available experimental data and with recommended evaluated data.
Large-scale shell-model calculations for even-odd 61−65 Fe isotopesSrivastava, P. C.;Mehrotra, I.
doi: 10.1134/s1063778810100030pmid: N/A
Abstract Large-scale shell-model calculations have been performed to calculate the negative-parity states of even-odd 61−65Fe isotopes. The results are compared with the recent experimental data reported at Legnaro National Laboratories and also with earlier calculations with fpg interaction in a truncated configuration space. It is observed that negative parity states of 61Fe can be well reproduced with GXPF1A interaction in full fp space without truncation. For 63Fe the correct ordering of levels is not reproduced. The structure of the wave function for the ground state and first excited state suggests that the ordering of the single-particle energy levels gets modified due to monopole correction.
Binding energies of even-even superheavy nuclei in a semi-microscopic approachIsmail, M.;Ellithi, A. Y.;Botros, M. M.;Adel, A.
doi: 10.1134/s1063778810100042pmid: N/A
Abstract The structure of some even-even superheavy nuclei with the proton number Z = 98−120 is studied using a semi-microscopic but not self-consistent model. The macroscopic energy part is obtained from the Skyrme nucleon-nucleon interaction in the semi-classical extended Thomas-Fermi approach. A simple but accurate method is derived for calculating the direct part of the Coulomb energy. The microscopic shell plus pairing energy corrections are calculated from the traditional Strutinsky method. Within this semi-microscopic approach, the total energy curves with the quadrupole deformation of the studied superheavy nuclei were calculated. The same approach features the well known 208Pb or 238U nuclei. For each nucleus the model predictions for the binding energy, the deformation parameters, the half-density radii and comparison with other theoretical models are made. The calculated binding energies are in good agreement with the available experimental data.
Description of superheavy nuclei on the basis of a modified version of the DF3 energy functionalTolokonnikov, S. V.;Saperstein, E. E.
doi: 10.1134/s1063778810100054pmid: N/A
Abstract The possibility of describing nuclei of the uranium and transuranium region within the generalized method of the energy functional proposed by Fayans and his coauthors is studied. It turned out that, in the functional DF3, it is necessary, for this purpose, to modify the spin-orbit terms whose parameters were chosen in such a way as to describe the binding energies and charge radii of spherical nuclei from calcium to lead. The modified functional (DF3-a) describes well the energy features and charged radii for isotopic chains of uranium and neighboring elements. For deformed nuclei, the deformation was taken into account approximately. The nucleon-drip-line position obtained for these chains proved to be close to the predictions of one of the most successful calculations by the Skyrme-Hartree-Fock method with the HFB-17 functional. It is verified that the use of the functional DF3-a does not impair the description of the properties of lighter nuclei, for which the functional DF3 was devised. Moreover, the modified functional describes better, than the original one, new data on spin-orbit splitting in magic and semimagic nuclei. The calculation with the functional DF3-a confirms the doubly magic nature of the superheavy nuclide 298114 X184. As for the neutron-separation energies S n along the isotopic chain of this element, our results are close to the predictions of the so-called micro-macro method.
Calculation of proton total reaction cross sections for some target nuclei in incident energy range of 10–600 MeVBüyükuslu, H.;Kaplan, A.;Aydin, A.;Tel, E.;Yıldırım, G.
doi: 10.1134/S1063778810100066pmid: N/A
Abstract In this study, proton total reaction cross sections have been investigated for some isotopes such as 12C, 27Al, 9Be, 16O, 181Ta, 197Au, 6Li, and 14N by a proton beam up to 600 MeV. Calculation of the proton total cross sections has been carried out by the analytic expression formulated by M.A. Alvi by using Coulomb-modified Glauber theory with the Helm model nuclear form factor. The obtained results have been discussed and compared with the available experimental data and found to be in agreement with each other.
Asymmetries in rare radiative leptonic and semileptonic decays of B mesonsBalakireva, I. A.;Nikitin, N. V.;Tlisov, D. A.
doi: 10.1134/s106377881010008xpmid: N/A
Abstract The time-dependent and time-independent CP asymmetries \( A_{CP}^{B_q^0 \to f} \left( \tau \right) \) and \( A_{CP}^{B_q^0 \to f} \left( {\hat s} \right) \) for rare semileptonic and radiative leptonic decays of B mesons are calculated by the method of helicity amplitudes. The sensitivity of CP asymmetries to various extensions of the Standard Model that have an operator basis that is identical to the operator basis of the Standard Model is investigated. It is shown that, by combining information about the form of the charge lepton asymmetry A FB at small values of the square of the invariant dilepton mass and information about the average value of the time-dependent CP asymmetry, one can in principle determine the relative phases of the Wilson coefficients C 7γ , C 9V , and C 10A in the effective Hamiltonian for b → {d, s}ℓ+ℓ− transitions.
Fragmentation production of charmed hadrons in electron-positron annihilationNovoselov, A. A.
doi: 10.1134/s1063778810100091pmid: N/A
Abstract Processes involving the production of D* mesons and Λ c baryons in electron-positron annihilation at the energies of 10.58 and 91.18 GeV are considered. At the energy of 10.58 GeV, the production of pairs of B mesons that is followed by their decay to charmed particles is analyzed along with direct charm production. The violation of scaling in the respective fragmentation functions is taken into account in the next-to-leading-logarithmic approximation of perturbative QCD. The required nonperturbative fragmentation functions are extracted numerically from experimental data obtained at B factories and are approximated by simple analytic expressions. It is shown that the difference in the nonperturbative fragmentation functions for transitions to mesons and baryons can readily be explained on the basis of the quark-counting rules.