A generalized time-dependent pseudopotential is defined. Analogue of the Newtonian equation is derived for stationary states and pseudoforces are physically interpreted. Physical points are also made from the analogous equation of continuity and the Euler equations.

It is demonstrated that the practical range of a beta spectrum (E_max=E) in any material can be obtained from mass absorption coefficient (μ/ρ) values. It is further shown that a semiempirical relation likeμ/ρ =AE^−B in whichA andB are related to the atomic numberZ, of the absorber can be used for determiningμ/ρ of any material of known atomic numberZ. Theβ particle ranges are compared with theoreticalcsda and practical ranges from literature.

Crystalloluminescence and temporary mechanoluminescence of As₂O₃ crystals are investigated. The crystalloluminescence spectra are similar to the photoluminescence and mechanoluminescence (of fresh crystals, in CO₂ atmosphere) spectra. The mechanoluminescence spectra of freshly grown crystals taken in air consist of the superposition of the photoluminescence and nitrogen emissions. The mechanoluminescence spectra of old crystals of As₂O₃ consist of only the nitrogen emission. The total number of crystalloluminescence flashes is linearly related to the total mass of the crystals grown. The mechanoluminescence intensity increases with the mass of the crystals. The mechanoluminescence intensity decreases with the age of the crystals and the rate of decrease increases with increasing temperature of the crystals. Different possibilities of crystalloluminescence and mechanoluminescence excitations in As₂O₃ crystals are explored and it is concluded that crystalloluminescence and mechanoluminescence are of different origins.

Hill-Coleman’s single frequency conductance technique for the determination of surface state density has been extended upto 2 kHz. A.c. conductance (G_m) and capacitance (C_m)versus gate bias (V_G) curves were obtained at various signal frequencies. Shift of the observed peaks in theG_m versus V_G curves for different signal frequencies was utilized for the determination of surface state density at different surface potentials (φ_s). Determination of surface state density for differentφ_s values was also done by Nicollian-Goetzberger method and the results compared. Results obtained by Hill-Coleman technique compare reasonably well with those obtained by the other method.

Following the treatment of Vega (1973), the theoretical expressions for the second moments in nuclear quadrupole resonance (nqr) due to dipole-dipole interactions have been derived for the system containing the nuclei with spinI=3/2. Cases with the orientation of the static magnetic field and the interactions with the other magnetic nuclei are also dealt with.

Collective field approach to O(N) Heisenberg spin system is discussed. Hamiltonian formulation is reviewed and connection with largeN limit is shown. Collective field is then introduced in the Lagrangian path-integral formulation and 1/N corrections to various quantities like mass-gap, beta-function are computed.

The real and imaginary parts of pion-nucleus optical potential arising from pion absorption channel have been computed. A two-nucleon model of pion absorption which includesπ andρ rescattering andS-wave interaction has been used. The effects of short-range nucleon-nucleon correlations, Pauli blocking and formfactors have been included. The threshold values of imaginary absorption potential are reasonably close to density-squared terms of phenomenological potentials. The real part ofP-wave potential is attractive and that ofS-wave potential is weakly attractive at lower pion energies and changes sign as pion energy is increased. The calculation shows that the real part of absorption is significantly affected by short-range correlations and Pauli-blocking.

In radiative decays of charged leptons induced by non-degenerate neutrino masses and consequent lepton flavour-mixing, the dominant suppression factor at the 1-loop level is (Σ m_a²)/m_W²,m_a being the mass of theath neutrino. We show that this suppression factor is presentin all orders in a class of models including the standard model.

The yield and energy distribution of long-range alpha-particles (lra) emitted from neutron-induced fission of²³⁵U have been measured at neutron energies; thermal, 125±12, 155±11, 185±10, 210±9, 240±9, 365±50 and 480±45 keV. The long-range alpha-particles were detected in cellulose nitrate track detector foils. Results showed an increase of about 50% in the yield at neutron energies in the region 150 keV≤E_n≤220 keV as compared to that of thermal neutrons. A calculation has been carried out to extract thelra to binary fission ratio forp-wave neutron induced fission.

An approximation procedure is described to calculate the projected energies from an intrinsicrpa hf wave function. The method of moments is used to find the relevant parameters. A model calculation is carried out for illustrative purposes.

In the present work a new graphical method is described to represent the resultant of the multiply reflected waves from coating systems consisting of single and double layers on metallic substrate, taking into account the optical phase properties of the films.