The XP1114 is a four stage photomultiplier on a B9A base. The spectral response is S11, that is blue sensitive. The emissive cathode is SbCs antimony-caesium.
The specification sheet attached to the box. The voltage across the tube is designed to be 800 Volts.
The flat end is the input window.
The cup structure is one of the four dynodes that emit secondary electrons and thus amplify the photo current.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 53 mm tall.
