Positron confinement by magnetic bottle for KoreA Experiment on Magnetic Monopole (KAEM)

Abstract

KoreA Experiment on Magnetic Monopole (KAEM) is designed to search for magnetically charged particles in the region of mass and charge below the electron mass and charge. It assumes the physics process $e^+ e^- \rightarrow m^+ m^-$, which can be produced by the annihilation of positrons decaying from $^{22}{{\textrm{Na}}}$ and the atomic electrons in a metal target. Since monopoles with low mass and a charge the same as the electron charge are likely to radiate violently (Hyper-EM) and be fully absorbed in a target, a very thin target is essential for magnetically charged particles to escape the target and reach calorimeters at both ends. However, a thin target has a low probability of annihilation. To solve this problem, we exploit a magnetic bottle to increase the probability of annihilation. In this paper, we report findings from Monte Carlo simulations of the magnetic bottle and a thin target utilizing a $^{22}{{\textrm{Na}}}$ source. These simulation studies conducted using GEANT4 provide access to understanding the behavior of charged particles in the magnetic bottle, enable predictions of positron confinement efficiency, and facilitate optimizing a target’s size.