Electron Multiplier Unit Compact Cylinder Length
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Solution Overview
Problem
Conventional photomultipliers used in medical inspection systems, such as γ-camera devices, face challenges in reducing the weight and size of heavy metal shields while maintaining detection resolution, as the number of photomultipliers needed increases with improved detection resolution, leading to increased weight and size of the apparatus.
Innovation Solution
An electron multiplier unit with a cascade multiplication structure that includes a first and second support member, a focusing electrode, and dynodes, which alters the trajectory of secondary electrons to achieve a longer travel path without increasing the diameter of the photomultiplier tube, allowing for a shorter cylinder length and higher gain with fewer stages of dynodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of photomultipliers is increased to improve detection resolution, then detection resolution is improved, but the weight and size of the apparatus increases
Solution Approach 1:
The patent changes the geometric parameters of the electron multiplier unit, specifically reducing the cylinder length and optimizing the arrangement of dynodes within a compact volume. This allows maintaining detection resolution while reducing the number of photomultipliers needed, thereby decreasing overall apparatus weight
2Measurement precision
If the number of photomultipliers is increased to improve detection resolution, then detection resolution is improved, but the size of the apparatus increases
Solution Approach 1:
The patent optimizes the three-dimensional arrangement of components within the electron multiplier unit, creating a more compact spatial configuration. By reorganizing the dynodes and support members in space, the unit achieves reduced volume while maintaining the necessary functional pathways for electron multiplication
3Volume of stationary object
If the cylinder length is reduced to decrease apparatus size, then size is reduced, but the gain and response characteristics may deteriorate
Solution Approach 1:
The patent optimizes the dynamic characteristics of electron flow through the compact structure by carefully designing the electric field distribution and electron trajectories. The support members and dynodes are positioned to ensure adequate electron multiplication gain and fast response time even within the reduced cylinder length
Solution Approach 2:
The patent changes geometric parameters including the spacing and arrangement of dynodes within the shortened cylinder, optimizing these parameters to maintain adequate electron travel paths and multiplication efficiency despite the reduced overall length
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The electron multiplier unit effectively reduces the cylinder length of photomultipliers while maintaining or improving detection resolution and response speed, enabling a lighter and more compact apparatus without compromising detection capabilities.
Implementation Method 1
The focusing electrode functions to alter trajectories of the photoelectrons, to guide the primary electrons (photoelectrons from the cathode in the case of a photomultiplier) to the inlet aperture provided in the first support member
Implementation Method 2
The first dynode is a dynode for receiving the primary electrons having passed through the inlet aperture of the first support member and for emitting secondary electrons
Implementation Method 3
an electron multiplier unit enabling cascade multiplication of electrons through successive emission of secondary electrons in multiple steps in response to incidence of primary electrons
Data Source
AI summary
This invention relates to an electron multiplier unit and others enabling cascade multiplication of electrons through successive emission of secondary electrons in multiple stages in response to incidence of primary electrons. The electron multiplier unit has a first support member provided with an inlet aperture for letting primary electrons in, and a second support member located so as to face the first support member. The first support member is provided with a focusing electrode functioning to alter trajectories of the primary electrons, in order to guide the primary electrons to the inlet aperture. These first and second support members hold an electron multiplication section for the cascade multiplication and an anode. The electron multiplication section comprises at least a first dynode of a box type and a second dynode having a reflection type secondary electron emission surface located so as to face the first dynode and arranged to receive secondary electrons from the first dynode and to emit secondary electrons to a side where the first dynode is located. The anode is located at a position where the secondary electrons emitted from the first dynode do not directly arrive, and the second dynode alters a travel path of secondary electrons so as to be kept in a space between the first and second support members.