Dual Probe Ionization Chamber for Alpha Particle Detection
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Solution Overview
Problem
Existing alpha particle detection apparatuses face challenges with high noise sensitivity, low detection efficiency, and high costs due to issues with signal-to-noise ratio and complex designs, particularly in ionization chambers.
Innovation Solution
The use of a dual probe structured ionization chamber combined with a differential amplifier effectively cancels external electrical noise and amplifies ionic signals from alpha decay, employing a DC bias voltage range of 50V to 200V and configuring the main and auxiliary probes to optimize signal detection and noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional ionization chamber is used for alpha particle detection, then the device structure is simple, but the noise sensitivity is high and detection precision is low
Solution Approach 1:
The detection chamber is divided into multiple independent probe units (first probe unit, second probe unit, third probe unit) with distinct functions. The first probe detects alpha particles, while the second and third probes detect noise signals. This segmentation allows simultaneous measurement of both signal and noise, enabling noise subtraction to improve detection precision without excessive complexity.
Solution Approach 2:
The patent introduces auxiliary probe units that act as intermediaries to detect noise signals separately from the main detection probe. These intermediary probes measure environmental noise that affects the main probe, allowing the system to subtract noise components from the total signal and thereby improve alpha particle detection precision.
2Measurement precision
If surface barrier type detectors are used, then energy resolution is good, but the device requires high voltage bias and has low detection efficiency
Solution Approach 1:
The patent changes the operating parameters by using low-voltage bias (5-50V) instead of the high voltages required by surface barrier detectors. The ionization chamber operates by collecting ions generated by alpha particle ionization of air molecules, which requires much lower voltages. This parameter change maintains good energy resolution while dramatically improving detection efficiency and reducing power consumption.
3Measurement precision
If high purity semiconductor detectors are used, then energy resolution is very high, but the device is expensive and requires liquid nitrogen cooling
Solution Approach 1:
The patent replaces expensive, fragile semiconductor detectors with a simple ionization chamber using basic electrical components. The detection medium is air itself, which is free and requires no special handling. The system uses inexpensive resistors, capacitors, and operational amplifiers instead of costly semiconductor materials and cooling systems, achieving adequate energy resolution at much lower cost and complexity.
4Measurement precision
If the ionization chamber is sealed to block external light, then light interference is prevented, but air circulation becomes poor requiring forced circulation pumps
Solution Approach 1:
The patent uses a porous or mesh structure for the chamber cover instead of a solid sealed cover. The mesh size is small enough to block external light effectively but large enough to allow free air circulation through the chamber. This eliminates the need for forced circulation pumps while maintaining light blocking capability, improving both detection accuracy and air flow efficiency.
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
This approach results in a high-sensitivity, low-noise alpha particle detection system that is cost-effective and compact, suitable for real-time continuous radon detection, enhancing measurement accuracy and reducing noise interference.
Implementation Method 1
an ionization chamber | forming electric field thereinside by bias power applied to a surface thereof; a main probe unit disposed within the ionization chamber
Implementation Method 2
a differential amplifier connected to output terminals of the first and second preamplifiers at a non-inverting terminal (+) and an inverting terminal (-) thereof, and canceling a noise signal and outputting an alpha particle detection signal by amplifying a voltage difference
Data Source
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AI summary
Disclosed in an alpha particle detection apparatus using a dual probe structured ionization chamber and a differential amplifier, the apparatus including: an ionization chamber forming electric field thereinside by bias power applied to a surface thereof; a main probe unit absorbing ionic charges generated in an occurrence of alpha (α) decay in the ionization chamber; a guard ring unit absorbing leakage current generated between the ionization chamber and the main probe unit and flowing the leakage current to a ground; an auxiliary probe allowing surrounding noise to be introduced therein; first and second preamplifiers amplifying fine electrical signals to a predetermined magnitude; and a differential canceling a noise signal and outputting an alpha particle detection signal by amplifying a voltage difference between the preamplified electrical signals. As such, it is possible to effectively detect alpha (α) particles which are a type of radiation.