• A R Usha Devi

      Articles written in Pramana – Journal of Physics

    • Photon polarisation asymmetries in (p,p′γ) experiments

      A R Usha Devi A Sudha Rao G Ramachandran

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      The Stokes parameters characterising the polarization of the photon in theγ-decay of12C*(1+) are examined in correlation with the scattered proton in12C(p,p′)12C*(1+). This opens up the possibility of efficiently determining empirically the six inelastic scattering amplitudes utilizing only 13 measurements. We identify several alternative sets of such measurements to encourage experimental efforts in this direction.

    • Polarized light

      G Ramachandran A R Usha Devi N S Saandeep Kannada Vardhana

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      Following the recent work of Chandleret al on quasi probability distributions for spin-1/2 particles, we show that polarized light can be interpreted in terms of trivariate probability distributions in two different ways by choosing the variates to correspond to (i) the co-ordinates on the Poincare sphere, (ii) the components of the spin operator of the photon. In either case, it is shown that the Margenau-Hill procedure leads to probability mass functions while the Wigner-Weyl approach leads to probability density functions and the well-known Stokes parameters are also realised as appropriate averages with respect to these distribution functions.

    • The geometry of Larmor nutation

      K N Srinivasa Rao A V Gopala Rao A R Usha Devi

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      The nutation accompanying the well-known Larmor precession discussed with respect to an inertial frame in an earlier paper is now considered in the rotating Larmor frame where the precession is absent and the nutation is therefore fully emphasized. It is shown that, in this frame, the nutating vector generates, in general, what may be called interpenetrating partial cones, the two parts of which merge into a single cone traced twice over, when the orbit of the charged particle changes to a circle — giving an immediate explanation of the discontinuous jump in the nutation frequency to twice its value as the orbit changes continuously from an ellipse to a circle.

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