Urgent call to all Guardians: Stop the fire contamination!
Ban-photons can be found more often on fire contamination missions. If you collect enough Ban-photons, you can exchange them for various items at the Firebreak trading post in GUARDIANS Headquarters.
Clear the five required fire contamination missions, then report your results to the Firebreak trading post to receive PA fragments as your reward.
Even if you have already received a reward, you can clear the five missions again and report your results to receive PA fragments as many times as you want.