Calculation device, light detection device, and gain calculation method

A calculation device is a device for calculating the gain of a photomultiplier, and is provided with: an acquisition unit for acquiring a digital signal based on a dark pulse output from a photomultiplier in a dark state; and a calculation unit that calculates the total electron number of the dark pulse on the basis of the digital signal, and calculates the gain of the photomultiplier on the basis of the total electron number. 运算装置是计算光电倍增管的增益的装置，并且具备：获取部，其获取基于从处于黑暗中状态的光电倍增管输出的暗脉冲的数字信号；以及计算部，其基于数字信号计算暗脉冲的总电子数，并基于总电子数计算光电倍增管的增益。