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Excitation functions of the reactions 107Ag[(α, n); (α, 2n); (α, αn); (α, α2n)] and,109Ag[(α, 2n); (α, 3n); (α, 4n); (α, α3n); (α, α4n)] were investigated up to 70 MeV by the stacked foil activation technique and Ge(Li) gamma-ray spectroscopy method. Since the natural silver used as the target has two odd mass stable isotopes of abundance 51.83% (107Ag) and 48.17% (109Ag), their activation in some cases gives the same residual nucleus through different reaction channels, but with very different Q values. In such cases, the individual reaction cross sections are separated with the help of the ratio of theoretical cross sections. The experimental cross sections were compared with the predictions of a pre-equilibrium hybrid model. The (α, xn) reactions are fairly well reproduced with initial exciton number n0 = 4(4p0h), whereas (α, αxn) reactions are underestimated in magnitude by a factor of five to six.

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Based upon the electromagnetic treatment, stimulated Brillouin scattering (SBS) in a centrosymmetric, doped semiconductor which is subjected to a transverse magnetic field is investigated analytically. The origin of this nonlinear interaction is considered to be found in the third order optical susceptibility arising due to non-linear current density and acousto-optic polarization of the medium. The threshold condition is obtained for the onset of the SBS. The effective Brillouin susceptibility and the resulting gain is determined using the coupled mode scheme. Using the effective third order polarization so achieved, authors have also calculated the transmitted intensity and Brillouin cell efficiency. The effect of magnetic field and doping on threshold field and Brillouin gain is also studied. Numerical estimations are made for n-InSb at 77 K duly shined by a pulsed 1 0 . 6 ~ CO, laser. The gain constant is significantly enhanced under high power pulsed excitation below the damage threshold and under the influence of a transverse magnetostatic field when the cyclotron frequency is less than the acoustic wave frequency. The required threshold electric field for the onset of the SBS process is also reduced significatly in the presence of a magnetostatic field. The minimum cell length required to achieve optical phase conjugation is found to be 0.45 pm.