Geomagnetic Backtracing: A comparison of Tsyganenko 1996 and 2005 External Field models with AMS-02 data

TL;DR

This study compares Tsyganenko 1996 and 2005 external magnetic field models by backtracing cosmic ray trajectories during high solar activity periods using AMS-02 data, highlighting their similarities at high energies.

Contribution

It provides a detailed comparison of two external field models with AMS-02 data, revealing their consistency at high energies during active solar periods.

Findings

At energies above 50 GV, the models produce similar particle trajectories.

The RMS angular difference between models is about a millirad at high energies.

Confirmed the East-West effect on primary particle trajectories.

Abstract

We used a backtracing code to reconstruct particle trajectory inside the Earth Magnetosphere during the last solar active period (2011 and 2012) when very high Solar Wind pressure values were measured. We compared our results on AMS-02 proton and electron data with 2 different External Field models, namely Tsyganenko 1996 (T96) and 2005 (T05), both for quiet (defined as the periods when the solar wind pressure is below the average value, set at 2nPa) and active periods. Although T05 has been specifically designed for storm events, at high energy the particle trajectory is similar for the two models. For instance at rigidities larger than 50 GV, the RMS of angular difference between reconstructed asymptotic direction outside the Magnetosphere is of the order of the millirad, while it increases at intermediate energies. We also confirmed, as a function of the pointing direction, the well known East-West effect on the trajectory of primary particles and on the access solid angle on the AMS detector.