The multiplication method of photomultiplier tubes mainly relies on the secondary electron emission effect, which amplifies the number of primary photoelectrons through a series of multiplier electrodes. The following is a detailed explanation of the photomultiplier tube multiplication method:

Dana Extreme Doubling Method:

The dynode multiplication method is the most common multiplication method in photomultiplier tubes.
In this method, each multiplier pole (also known as the dynode) operates at a higher voltage than the previous one, and the voltage difference between adjacent poles causes the secondary emission coefficient to be greater than 1.
The electrons emitted by the photocathode shoot towards the first stage multiplier at high speed under the action of an electric field, producing more secondary emitted electrons.
These electrons are accelerated and collided with the next order of multiplication poles, resulting in a series of geometric multiples.
Finally, the electrons reach the anode, and the sharp current pulses formed by the accumulation of charges can characterize the input photons.
Commonly used dynode materials include cesium antimonide, silver magnesium oxide alloys, and copper beryllium oxide alloys, which have high secondary emission coefficients at lower incident electron energies.

Microchannel Plate (MCP) Multiplication Method:

Microchannel plate is a new type of multiplication technology, consisting of two thin glass or ceramic plates with a large number of tiny channels etched on them.
When primary photoelectrons enter the microchannel plate, electrons reflect multiple times within the channel and undergo secondary electron emission, thereby achieving rapid electron multiplication.
MCP consists of thousands of microchannels, each with a precisely designed length and diameter to optimize electron multiplication efficiency and reduce electron diffusion.
MCP materials are usually lead glass or borosilicate glass, which have good secondary electron emission characteristics and chemical stability.

Focused and non focused multiplication systems:

In the dyno doubling system, electrons can be further classified into focused and unfocused types based on their focusing mode.
The design of the dynode in a focused multiplication system is to focus electrons from the previous stage to the next stage after multiplication, which can increase gain but may also lead to electron diffusion and signal distortion.
The design of the dynode in a non focusing multiplication system is to not focus electrons, but to achieve electron transfer and multiplication through a simple geometric arrangement. The advantages of this method are simple structure, low electron diffusion, low signal distortion, but relatively low gain.

The characteristics of the doubling process:

The multiplication process of a photomultiplier tube usually involves multiple multiplication electrodes, each of which can double the number of electrons.
By reasonable voltage distribution and selection of electrode materials, efficient electron multiplication and signal amplification can be achieved.
During the entire doubling process, the number of photoelectrons increases geometrically, achieving high sensitivity detection of weak light signals.

The multiplication method of photomultiplier tubes mainly relies on the dynode multiplication method and microchannel plate multiplication method. Through reasonable multiplication electrode design and voltage distribution, efficient detection and amplification of weak light signals can be achieved.