arXiv subjects

O. S. K. S Sastri

Publications and source records attributed to O. S. K. S Sastri.

4 recordsLinked to original sources

arXiv2024

Algorithm to Obtain Inverse Potentials for $α-α$ Scattering using Variable Phase Approach

An algorithm$^{\ref{Fig1}}$ has been developed with the purpose of obtaining inverse potentials, where the Riccati-type non-linear differential equation, also called phase equation, has been kept in tandem with the Variational Monte Carlo method. The optimization of Gaussian function parameters is achieved such that the experimental phase shifts are reproduced. The obtained SPS for various $\ ell$ channels has been compared with experimental ones with mean absolute percentage error (MAPE) as a measure. The model parameters have been optimised by suitable optimisation technique by looking for minimum value of MAPE. The results for $\ell$=0$^+$, 2$^+$ and 4$^+$ partial waves have been obtained, to match with experimental SPS, with MAPE values of $2.9$, $4.6$ and $6.2$ respectively for data up to $23$ MeV, while for higher states 6$^+$, 8$^+$ and 10$^+$ has MAPE of $3.2, 4.5$ and $5.9$ respectively for data from $53-120$ MeV. On extrapolation for data in range E$_{\ell ab.}$ = $23-120$ MeV, using the optimised parameters, the SPS are found to be in close agreement with experimental ones for the first three channels.

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arXiv2023

Study of np-scattering for S, P and D Waves using Deng-Fan Potential by Phase Function Method

In this paper, the np - scattering phase shifts and cross section for S,P and D partial waves have been obtained for energies below the pion threshold, by considering Deng-Fan potential as model of interaction. The radial time independent Schrödinger equation has been analytically solved using Nikiforov - Uvarov method to obtain the energy expression for ground state of np system. Utilising this, the scattering phase shifts for $^3S_1$ have been obtained using phase function method. The phase equations for various scattering states $^1S_0$, $^1P_1$, $^3P_{0,1,2}$, $^1D_2$, and $^3D_{1,2,3}$ have been numerically solved for obtaining corresponding scattering phase shifts and their respective partial cross section. The total scattering cross sections computed at various energies are found to be closely matching with experimental data. The low energy scattering parameters determined from scattering phase shifts of $^3S_1$ and $^1S_0$ are reasonably close to experimental ones. Hence, Deng-Fan potential is a good phenomenological potential to understand the np - scattering system.

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arXiv2022

Deuteron Structure and Form Factors: Using Inverse Potentials for S-waves

In this paper, we determine deuteron's static properties, low energy scattering parameters, total cross-section and form factors from inverse S-wave potentials constructed using Morse function. The scattering phase shifts (SPS) at different lab energies are determined using phase function method. The model parameters are optimised using both machine learning algorithm and traditional data analysis by choosing mean squared error as cost function. The mean absolute error between experimental and obtained SPS for states 3S1 and 1S0 are found to be 0.35 and 0.70 respectively. The low energy scattering parameters are matching well with expected values. The contribution due to S-waves SPS towards total cross-section at various energies have been obtained and are matching well with experimental values. The analytical ground state deuteron wave-function (DWF) is obtained by utilizing the experimental value for Quadrupole moment. Other static properties and form factors determined from obtained DWF are found to be in close agreement with experimental ones.

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arXiv2022

Phase Shift Analysis of Light Nucleon-Nucleus Elastic Scattering using Reference Potential Approach

The neutron and proton scattering with either deuteron or stable alpha particle can be modeled as a two particle system. In this paper, using Morse function as reference potential, inverse potentials have been computationally constructed directly from scattering phase shifts (SPS) data for light nucleon-nucleus systems. The phase equation for various l-channels has been numerically solved using 5th order Runge-Kutta (RK-5) method in each iteration within the optimization procedure to obtain best model parameters of Morse function that minimize mean absolute percentage error (MAPE). The inverse potentials for S-wave of neutron-deuteron and proton-deuteron systems have been obtained with MAPE of 1.95 and 2.05% respectively. Those corresponding to various P and D channels of neutron-alpha(n-alpha) and proton-alpha(p-alpha) systems, have been determined to less than 1.53 and 2.17% respectively. The obtained(experimental) resonance energies for p1/2 and p3/2, from their partial cross-sections plots, respectively are 4.1(4) and 0.93(0.89) for n-alpha and 5.21(5) and 1.96(1.96) for p-alpha system. While total cross-section for n-alpha has been found to be matching with values available in literature, that of p-alpha is seen to be following the correct trend.

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