An inverse response matrix converts the observed pulse-height distribution of a NaI(Tl) scintillation detector to a true photon spectrum. This also results in extraction of intensity and energy distributions of multiply scattered events originating from interactions of 279 keV photons with thick targets of bronze. The observed pulse-height distributions are a composite of singly and multiply scattered events in addition to bremmstrahlung originating from slowing down of Compton and photo-electrons in thick targets. To evaluate the contribution of multiply scattered events, the spectrum of singly scattered events contributing to inelastic Compton peak is reconstructed analytically. The optimum thickness (saturation depth), at which the number of multiply scattered events saturate, has been evaluated in different energy bin meshes chosen for scintillation detector response unfolding. Monte Carlo calculations based upon the package developed by Bauer and Pattison (Compton scattering experiments at the HMI (1981), HMI-B 364, pp. 1-106) supports the present experimental results.

The existence of the large-amplitude dust inertial Alfvén waves (DIAWs) has been presented in an electron-depleted, two-fluid dust-ion plasma. Linear analysis shows that the DIAWs travel slower than the dust Alfvén waves. DIAWs are the obliquely (with respect to the external magnetic field) propagating oscillations ofdust density, having the characteristics of a solitary wave. In order to observe the nonlinear behaviour of the DIAWs, the Sagdeev pseudopotential method has been used to derive the energy balance equation and from the expressionof the Sagdeev pseudopotential, the existence conditions for the DIAWs have also been determined. It is observed that density rarefactions travelling at sub- and super-Alfvénic speeds are associated with DIAWs.