Patent ID: 8492694

Claim:
A photomultiplier tube comprising: a housing having a substrate in which at least an inner surface is formed with an insulating material; an electron multiplying part having N stages (N denotes an integer of two or more) of dynodes arrayed so as to be spaced away sequentially along one direction from a first end side on the inner surface of the housing to a second end side; a photocathode which is installed on the first end side inside the housing so as to be spaced away from the electron multiplying part, converting incident light from outside to photoelectrons to emit the photoelectrons; and an anode part which is installed on the second end side inside the housing so as to be spaced away from the electron multiplying part to take out electrons multiplied by the electron multiplying part as a signal, wherein each of the N stages of dynodes is arranged on the inner surface, provided with a plurality of columnar parts where secondary electron emitting surfaces are formed, thereby forming electron multiplying channels having the secondary electron emitting surfaces between adjacent columnar parts among the plurality of columnar parts, and a first recessed surface which opposes the columnar part of an M th stage dynode at the columnar part of an M+1 th stage (M denotes an integer of one or more but less than N) dynode is formed in such a manner that first and second end edges of the first recessed surface in a direction along the inner surface project to the first end side from a location on the first recessed surface opposing an end edge of the second end side on the secondary electron emitting surface at the columnar part of the M th stage dynode.