Electron multiplier and photomultiplier tube

An electron multiplier comprising:

• a main body portion extending in a first direction;
• a first channel that is provided in the main body portion to open at one end surface and the other end surface of the main body portion in the first direction and emits secondary electrons according to incident electrons;
• and
• a second channel that is provided in the main body portion to open at the one end surface and the other end surface in the first direction and emits secondary electrons according to the incident electrons,
• wherein the main body portion includes a first plate-shaped member and a second plate-shaped member that are stacked on each other in a second direction intersecting the first direction to form the first channel and the second channel,
• the first plate-shaped member includes a first front surface and a first back surface intersecting the second direction, a first hole portion area in which a first hole portion reaching the first back surface from the first front surface and extending along the first front surface and the first back surface is formed, and a first solid area adjacent to the first hole portion area,
• the second plate-shaped member includes a second front surface and a second back surface intersecting the second direction, a second hole portion area in which a second hole portion reaching the second back surface from the second front surface and extending along the second front surface and the second back surface is formed, and a second solid area adjacent to the second hole portion area,
• the first hole portion area faces the second solid area in the second direction,
• the second hole portion area faces the first solid area in the second direction,
• the first channel is formed to include an inner surface of the first hole portion and a surface of the second solid area facing the inside of the first hole portion,
• the second channel is formed to include an inner surface of the second hole portion and a surface of the first solid area facing the inside of the second hole portion,
• a third hole portion that reaches the first back surface from the first front surface and extends from the one end surface to be connected to the first hole portion is provided in the first plate-shaped member,
• a fourth hole portion that reaches the second back surface from the second front surface and extends from the one end surface to be connected to the second hole portion is provided in the second plate-shaped member,
• the third hole portion and the fourth hole portion overlap each other in the second direction, and
• a channel entrance defined by the third hole portion and the fourth hole portion has a tapered shape.