Analysis of an interferometer with acoustic surface waves on one mirror.
It has been demonstrated that surface waves propagating on one mirror of an interferometer form an optical diffraction grating. Experimentally confirmed analyses of an interferomet er with 95.5% reflectivity mirrors now indicate that a surface wave power density of 0.028 mW/mm.MHz is required to diffract 1% of transmitted light into the first order beam. This power can be diminished by a factor of more than 20 by increasing the mirror reflectivity to 99%.
10. Surface Elastic Waves
Publisher Summary This chapter describes the surface waves in semi-infinite and layered media. A surface wave is considered an organized propagating disturbance, having a wavelike character whose energy is concentrated near the surface of the medium. The particle displacement can be sensed by optical means, and it can be inferred from the transport of small particles along the surface in a direction opposite to that of wave propagation owing to the retrograde elliptical motion of the surface atoms. Electrical boundary conditions at the surface provide a connection between the electric field inside the solid resulting from the deformation and the associated field outside. At a non-conducting boundary plane, the components of electric displacement tangential to the boundary must be continuous. Properties usually listed as functions of direction for propagation in a given homogeneous material include phase velocity and strength of piezoelectric coupling. The angle between the propagation vector and the power flow vector in anisotropic materials is a computed characteristic of experimental importance.
5.63 and 5.80 MeV levels of Ne20; de-excitation branching
Abstract The ratio Г γ /Г for the 5.63 and 5.80 MeV levels of Ne 20 has been determined to be 0.077 (±0.008) and −4 , respectively, by using the C 12 (C 12 , α)Ne 20 reaction and determining the fraction of the events in which the alpha-particle and the Ne 20 recoil are present in coincidence at the kinematically correct angles. In both cases these results in themselves are shown to imply radiative E1 transition (5.63→1.63 and 5.80→0, respectively) probabilities ⪡5 × 10 −5 Weisskopf units. When taken together with the life-time for the 5.63 MeV level measured by Evans et al . values of Г( E1 ) ≲ 5 × 10 −6 and Г α ≈ 6% of the particle estimate are obtained for this state.