Measurement of neutral mesons and thermal radiant photons under the world's highest energy

The authors are conducting research on the material phase 'quark - gluon - plasma (QGP) phase' where quarks and gluons are released from hadron confinement, using the CERN laboratory's LHC accelerator. This state of matter is thought to be the appearance of our universe 10-6 to 10-5 seconds after the Big Bang, and studying it will lead to the elucidation of the state of matter in the very early universe. This paper describes the results of neutral meson measurement and thermal radiant photon measurement in the world's highest energy lead + lead nuclei collision experiment conducted in the ALICE experiment, as well as the prospects for the third phase data acquisition of the LHC accelerator starting in 2022. (A.O.)