• Pushpa M Rao

      Articles written in Pramana – Journal of Physics

    • Numerical calculations of potential distribution in non-ideal quadrupole trap and simulations of anharmonic oscillations

      Anita Gupta Pushpa M Rao

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      A quadrupole ion trap consisting of electrode structures symmetric about 𝑧-axis is an important tool for conducting several precision experiments. In practice the field inside the trap does not remain purely quadrupolar, and can be calculated using numerical methods. We have used boundary element method to calculate the potential inside the truncated as well as symmetrically misaligned quadrupolar ion trap. The calculated potential values are fitted to multipole expansion and the weights of multipole moments have been evaluated by minimizing the least square deviation. The higher-order multi-pole contribution in the fabricated hyperbolic electrodes due to truncation and machining imperfections is discussed. Non-linear effects arising due to the superposition of octupole moment manifest as anharmonic oscillations of trapped ions in the non-ideal Paul trap. Theoretical simulations of non-linear effects have been carried out.

    • Optical probing of Eu ions confined in an RF trap

      Pushpa M Rao Anita Gupta

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      The Eu ions confined in an RF quadrupole trap, has been optically detected. Using a tunable dye laser which is pumped by a Nd-YAG pulsed laser system, the resonance ${}^9S_4–6 p_{3/2}$, $J = 5$ transition of the Eu ions have been excited and the resulting fluorescence to the metastable ${}^9 D_{4−6}$ state has been detected. In preparation to determine the ground-state hyperfine splitting of the odd isotopes we found the optimum trapping operating point. We have also observed a number of instabilities inside the region of the stability for an ideal trap. These non-linear resonances arise from higher-order contributions to the ideal quadrupole potential.

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