PT Journal AU DUNE Collaboration (Abud, AAea Antonova, M Barenboim, G Cervera-Villanueva, A De Romeri, V Fernandez Menendez, P Garcia-Peris, MA Martin-Albo, J Martinez-Mirave, P Mena, O Molina Bueno, L Novella, P Pompa, F Sorel, M Ternes, CA Tortola, M Valle, JWF TI Scintillation light detection in the 6-m drift-length ProtoDUNE Dual Phase liquid argon TPC SO European Physical Journal C JI Eur. Phys. J. C PY 2022 BP 618 - 29pp VL 82 IS 7 DI 10.1140/epjc/s10052-022-10549-w LA English AB DUNE is a dual-site experiment for long-baseline neutrino oscillation studies, neutrino astrophysics and nucleon decay searches. ProtoDUNE Dual Phase (DP) is a 6 x 6 x 6 m(3) liquid argon time-projection-chamber (LArTPC) that recorded cosmic-muon data at the CERN Neutrino Platform in 2019-2020 as a prototype of the DUNE Far Detector. Charged particles propagating through the LArTPC produce ionization and scintillation light. The scintillation light signal in these detectors can provide the trigger for non-beam events. In addition, it adds precise timing capabilities and improves the calorimetry measurements. In ProtoDUNE-DP, scintillation and electroluminescence light produced by cosmic muons in the LArTPC is collected by photomultiplier tubes placed up to 7m away from the ionizing track. In this paper, the ProtoDUNE-DP photon detection system performance is evaluated with a particular focus on the different wavelength shifters, such as PEN and TPB, and the use of Xe-doped LAr, considering its future use in giant LArTPCs. The scintillation light production and propagation processes are analyzed and a comparison of simulation to data is performed, improving understanding of the liquid argon properties. ER