Patent ID: 6946792

Claim:
A photomultiplier tube comprising: a tube-shaped vacuum vessel ( 2 ) extending along the tube axis (X); a photocathode ( 2 A) positioned on one end of the tube axis of the tube-shaped vacuum vessel ( 2 ) for photoconverting incident light to emit electrons; first to n th dynodes (Dy 1 -Dy 10 ), each having a secondary electron surface formed on an inner wall for multiplying electrons sequentially; and an anode (A) for receiving the electrons multiplied by the first to n th dynodes (Dy 1 -Dy 10 ), characterized in that a first dynode (Dy 1 ) is positioned opposite to the photocathode ( 2 A), when i is an integer greater than or equal to 2 and less than or equal to (n−1), a secondary electron surface of an i th dynode is positioned opposite to a secondary electron surface of an (i−1) th dynode and a secondary electron surface of an (i+1) th dynode, Dynodes having the same shape as a shape of a second dynode (Dy 2 ) are used as an (n−2) th dynode and an (n−1) th dynode (Dy 8 , Dy 9 ), while smaller dynodes than the second dynode (Dy 2 ) are used as a third dynode and a fifth dynode (Dy 3 , Dy 5 ), the first to n th dynodes are arranged so that a path formed in a spaces between opposing dynodes crosses the tube axis, a mesh type of anode is used as the anode (A), the mesh type of anode is placed on an opposite side of the second dynode (Dy 2 ) with respect to the tube axis (X).