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The lateral energy distribution and the lateral decay length of the shear horizontal wave (SH wave) at 5.6 MHz are investigated experimentally by using a waveguide for the SH wave made by evaporating a conductive Al film onto a PZT ceramic plate polarized parallel to its surface. Experimental results are well explained by a simplified theory along the same line as Tiersten's. The propagation loss of the guided SH wave is 0.18 dB/µsec. Moreover it is shown that the Bleustein-Gulyaev wave which corresponds to the zeroth-order SH wave in the case of an infinitely thick plate can be guided by a conductive film. A circular waveguide of diameter 40 mm prepared on a PZT disk of thickness 0.25 mm, polarized radially and parallel to the surface, has a delay time 53 µsec and an insertion loss 39.7 dB.

We note that the attenuation of a monochromatic beam of ${K}_{2}$ mesons in an absorber is not simply describable in terms of a single "mean free path," even when the extent of the absorber is large in comparison with the ${K}_{1}$ mean decay length. The normal attenuation factor $\mathrm{exp} (\ensuremath{-}N\ensuremath{\sigma}L)$ is to be corrected by a factor whose logarithm is nonlinear in the density $N$. The magnitude of this extra effect is discussed with the aid of a simple-minded model. The relation of the effect to the ${K}_{1}\ensuremath{-}{K}_{2}$ mass difference is briefly noted.

A time-of-flight technique has been used to investigate the lifetime $\ensuremath{\tau}$ of the long-lived $^{3}P_{0}$ and $^{3}P_{2}$ states of neon, argon, and krypton. The results are, for neon, $\ensuremath{\tau}(^{3}P)g0.8$ sec; for argon, $\ensuremath{\tau}(^{3}P)g1.3$ sec; and for krypton, $\ensuremath{\tau}(^{3}P)g1.0$ sec. The present measurements are limited by residual-gas or beam-beam scattering and by the length of the time-of-flight region being short compared to a decay length.

Limits of g ${10}^{5}$ astronomical units are set on the decay length of an electron antineutrino ${\overline{\ensuremath{\nu}}}_{e}$ via the process ${\overline{\ensuremath{\nu}}}_{e}\ensuremath{\rightarrow}{\ensuremath{\nu}}^{\ensuremath{'}}+\ensuremath{\gamma}$ for ${E}_{\ensuremath{\gamma}}$ in the range 0.1-0.5 MeV using the results from a well-shielded detector in the vicinity of a fission reactor. This mode of decay is therefore ruled out as a possible explanation for the paucity of solar neutrinos revealed by the experiment of Davis.