Toward Ultra-Intense Magnetic Field Detection with the ALICE Detector at LHC

The magnetic field naturally generated in non-central collisions of relativistic heavy ions is the most intense in the entire Universe, well exceeding that on the magnetar surfaces, and attracting broad physics interests.  The peak intensity reaches ~10¹⁵ (10¹⁴) T at the LHC (RHIC) energies.  More interestingly, it may stay intense enough to cause peculiar non-perturbative physics phenomena over a few fm/c or even more after the collisions, despite its rapid decay from the peak.

The field may sustain even longer due to, e.g., the rotating fireball.  The time structure or the decay pattern of the field should strongly affect its consequences.  Direct detection and evaluation of the effective field intensity is hence vital before discussing physics phenomena such as chiral magnetic effects.  We have proposed to utilize the possible polarization of direct virtual photons from pQCD processes, which can be experimentally measured via dileptons.  Feasibility and prospects of such approaches at the ALICE Run 3 (2022 – 2025) will be discussed.