M. L. Rustgi

Green's function solution to the tissue bioheat equation.

A Greens function solution to the tissue bioheat equation including blood flow in cylindrical geometry is obtained. Numerical results for temperature variation in the bovine muscle are reported when the tissue is exposed to neodymium-yttrium-aluminum garnett (Nd:YAG) lasers with Gaussian profile and a comparison with recent measurements is made. A strong dependence of the tissue temperature on the beam radius and pulse time is found.

Application of intermediate-coupling unified nuclear model to odd-mass iodine isotopes

Abstract Employing the intermediate-coupling unified nuclear model, the properties of the low-lying levels of the odd-mass iodine isotopes are investigated. The electromagnetic transition probabilities and nuclear moments are also calculated. In most cases, the results are found to be in fairly satisfactory agreement with the experimentally observed values. A number of energy levels is predicted which should stimulate new measurements.

Spatially dependent effective mass and optical properties in finite parabolic quantum wells

The effects of the spatial dependence of the effective mass in GaAs/AlxGa1−xAs parabolic quantum wells on several of their optical properties have been calculated. The largest effects are on the conduction‐band levels which are lowered with respect to those with constant effective mass. Effects on oscillator strengths, hole energy levels, and electron/hole overlaps are small.

Proposed polarized-target-beam test for 3S1-3S1 radiative transitions in thermal n-p capture

Abstract The development of techniques for producing polarized-proton targets and polarized-neutron beams may make it possible to set an upper limit on the probability of transitions from the 3 S 1 states in the continuum of the low-energy n+p system to the 3 S 1 part of the deuteron ground state. The absence of such transitions has been assumed in traditional theories of the thermal-energy neutron capture, as a consequence of the orthogonality of two eigenfunctions of a Schrodinger equation corresponding to two different energies. The applicability of this reasoning to the physical situation is discussed with the conclusion that it is not necessarily valid even apart from the slight effect of the admixture of the 3 D 1 to the 3 S 1 state. The density matrix of the colliding particles with arbitrarily assigned polarization vectors of beam and target is then used to calculate the angular distribution and degree of polarization of the capture gamma rays. It is found that if the whole of the approximately 9% “interaction effect” of Austern is to to be accounted for by 3 S 1 → 3 S 1 transitions, without any modification of the spin-flip transition intensity, asymmetries in the gamma-ray angular distribution ranging from 23% to 1.98% at a geometric-mean target-beam polarization of 0.954 to 0.577 respectively may be found. Larger or smaller effects may result depending on whether the spin-flip transitions are inhibited or enhanced by n-p interaction and structure effects. Appreciable effects on gamma-ray polarization are expected under conditions leading to appreciable gamma-ray angular distribution effects.

Electric‐field dependence of observables in finite parabolic quantum wells

The electric‐field dependence of eigenvalues, eigenfunctions, electron‐hole overlap integrals, and dipole moments in several finite parabolic quantum wells are calculated with the shooting method and compared with corresponding results for a square well. The results are more strongly field dependent for parabolic wells with a fixed‐volume integral than those for the square well. Reasons for this behavior are discussed.

A comparative study of electron transport phenomenon in the keV range

On incorporating two different electron inelastic scattering cross sections by Moller [Z. Phys. 70, 786 (1931)] and Gryzinski [Phys. Rev. 138, 336 (1965)], Monte Carlo calculations have been performed to calculate the energy, angular distribution, and coefficients of transmitted and backscattered electrons in Al films of different thicknesses for 15‐ and 20‐keV incident electron energies. The calculations from both the models are found to yield similar results and both of them give good agreement with the available experimental data.

Sum rules for the d(γ, n)p process employing realistic potentials

Abstract Employing the Yale and Hamada-Johnston potentials, the bremsstrahlung-weighted and integrated cross sections have been evaluated for the d(γ, n)p process. The electric polarizability of the deuteron is also calculated. The results are compared with experiments by nemerically integrating the total cross-section curve versus the energy of the γ-ray ( E ) for three moments weighting 1, E −1 and E −2 . The results are found to be quite insensitive to the details of these potentials. A study of the sum rules for the photodisintegration of the deuteron therefore may not provide any important information which may be useful in distinguishing between the various nucleon-nucleon potentials.

Two coupled parabolic wells under an electric field

The tunability of the states of two coupled parabolic quantum wells subjected to an electric field is studied by using the transfer‐matrix approach. Two numerical procedures are used. Both involve subdividing the potential profile into a number of linear or step partitions. For the linear partition approach, the Airy function solution of the Schrodinger equation is employed while for the step approach, the plane‐wave solution is used. Both methods give identical results if small enough partition intervals are used. It is found that the plane‐wave method is easier and that it simplifies the programming without seriously sacrificing the calculational speed. The coupled well width, the barrier width, and the applied field were changed systematically to study the changes in the energy levels, wave functions, and transmission of a resonant tunneling diode based on the double parabolic structure. The anticrossing between the energy levels on changing the well width or the bias of the coupled wells is seen and d...

Intersubband transitions in an asymmetric quantum well with a thin barrier or a delta‐function potential

The changes in the bound‐state energies and oscillator strength for intersubband transitions brought about by a thin barrier in the middle of an asymmetric quantum well are calculated, with a particularly close look at such changes as the middle barrier height approaches the bound‐state energies. It is found that the oscillator strength goes through a slight change as the barrier height approaches the ground‐state energy but an abrupt change when it approaches the excited bound‐state energy. A suitable explanation for this change is provided. A similar tailoring of the intersubband transitions is also achieved by placing a delta‐function potential in the vicinity of the middle of the well but without any abrupt change in the oscillator strength.

Theoretical investigation of the photodisintegration of deuteron at 0° for the outgoing protons

Abstract The serious discrepancy between the measurements of Hughes, Zieger, Waffler, and Ziegler and published calculations for the differential cross section for the photodisintegration of the deuteron at 0° for the outgoing protons is found to be greatly reduced when calculations with supersoft core potentials are carried out. The measurements seem to favor a lower percentage of the ‘D’ state of the deuteron.