Electron multiplier body, photomultiplier tube, and photomultiplier

An electron multiplier body, comprising:

• a main body portion extending in a first direction;
• an electron incidence portion provided in the main body portion to be opened at one end surface of the main body portion in the first direction, and on which electrons are incident from the outside of the main body portion;
• and
• a channel provided in the main body portion to be opened at the other end surface of the main body portion in the first direction and reach the electron incidence portion and configured to emit secondary electrons according to electrons incident from the electron incidence portion,
• wherein the channel includes a first inner surface and a second inner surface extending over the entire channel in the first direction and facing each other,
• the first inner surface includes a convex first bent portion and a concave second bent portion arranged alternately in the first direction, and a plurality of first inclined surfaces defining the first bent portion and the second bent portion,
• the second inner surface includes a convex third bent portion and a concave fourth bent portion arranged alternately in the first direction, and a plurality of second inclined surfaces defining the third bent portion and the fourth bent portion,
• the first bent portion and the fourth bent portion are arranged to face each other in a second direction directed from the first inner surface to the second inner surface,
• the second bent portion and the third bent portion are arranged to face each other in the second direction, and
• when an interval between a tip of the first bent portion and a tip of the third bent portion in the second direction is h, a distance between the first inclined surface and the second inclined surfaces facing each other is d, an angle between a pair of first inclined surfaces defining the first bent portion is θ, and a length of the channel in the first direction is L, Expressions (1) to (4) below are satisfied
• [Expression 1]
• −0.5≦h/d≦0.5 (1)
• [Expression 2]
• 96°≦θ≦172° (2)
• [Expression 3]
• 0.1 mm≦d≦10 mm (3)
• [Expression 4]
• 4.0 mm≦L≦400 mm (4).