Scintillation of XP2020 PMT glass window

•The scintillation properties of a PHOTONIS XP2020 PMT glass window have been studied.•The irradiation with gamma and neutron sources has been performed.•The glass window scintillation has to be considered when high-precision timing experiments are to be performed.

Scintillation of the photomultiplier glass window and its effects on the detector response were studied. It was proved that effects could have a considerable contribution to the pulse-height spectrum, especially when low-efficiency scintillators were used.