Scintillation Event Capture Using Image Intensifier Gating
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Solution Overview
Problem
Existing gamma ray detection systems using fiber-optic scintillators face challenges in accurately recording scintillation light due to its weakness and noise levels, particularly with charge-coupled devices (CCDs), which are exacerbated by the introduction of noise from image intensifiers used for amplification.
Innovation Solution
The system employs image intensifiers with a suitable decay time, coupled with sensors that operate in clear, acquisition, and read modes to mitigate noise by separating streaked image data from focused image data, allowing for precise capture and recording of scintillation light intensities and locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If image intensifiers are used to amplify scintillation light, then the light intensity is improved above CCD noise levels, but noise is introduced to the system
Solution Approach 1:
The system uses periodic gating of the image intensifier and sensor operation. The image intensifier is activated only during the scintillation light emission window, and the sensor switches between clear mode and acquisition mode periodically. This periodic action allows the system to capture amplified scintillation light while minimizing the integration of continuous noise from the image intensifier.
Solution Approach 2:
The sensor operates in clear mode before acquisition mode to pre-clear any accumulated noise or residual signals. This preliminary clearing action ensures that when the sensor switches to acquisition mode to capture the amplified scintillation light, the baseline noise level is minimized, thereby improving the signal-to-noise ratio.
2Object-generated harmful factors
If sensors operate in clear mode continuously, then noise is minimized, but scintillation light cannot be captured
Solution Approach 1:
The sensor alternates between clear mode and acquisition mode in a periodic fashion. During clear mode, the sensor clears accumulated noise and residual signals. During acquisition mode, the sensor captures the amplified scintillation light from the image intensifier. This periodic switching optimizes both noise minimization and signal capture.
Solution Approach 2:
The system dynamically switches the sensor operation mode based on the timing of scintillation events. The sensor transitions from clear mode to acquisition mode precisely when scintillation light is expected, allowing adaptive optimization of noise rejection and signal capture timing.
3Ease of operation
If the switching time from clear mode to acquisition mode is long, then mode transition is complete, but scintillation light may be missed
Solution Approach 1:
The sensor is pre-configured and pre-biased in clear mode with all switching circuits prepared. When a scintillation event is detected or expected, the transition to acquisition mode can occur rapidly because the necessary circuit conditions are already established, minimizing the switching time and preventing loss of scintillation light.
Solution Approach 2:
The system uses rapid switching techniques to transition the sensor from clear mode to acquisition mode in minimal time. Fast switching circuits and optimized timing control allow the sensor to 'rush through' the mode transition quickly, capturing scintillation events that occur during the brief switching interval without significant loss.
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 effectively amplifies scintillation light to overcome CCD noise levels while minimizing noise introduction, enabling accurate detection and identification of gamma rays by focusing amplified light at specific locations on sensors.
Implementation Method 1
an image intensifier may be used to amplify the scintillation light
Implementation Method 2
amplification of the scintillation light before it reaches the CCD
Implementation Method 3
image intensifiers with phosphors having a suitably chosen decay time
Implementation Method 4
sensors, which are optically coupled to respective ones of the image intensifiers, are initially operated in a clear mode
Data Source
AI summary
A photon generating event capture system is configured to capture light photons. Image intensifiers are arranged to amplify light photons and sensors are arranged to capture the amplified light photons. A control system detects the amplification of light photons by the image intensifiers. Upon detecting amplification, the control system deactivates the image intensifiers to shutdown further light photon amplification and switches the sensors from a clear mode to an acquisition mode within a period of time less than a decay time of the image intensifiers. The locations and intensities of the amplified light photons are then captured and read out by the sensors. By operating the sensors in a clear mode prior to detecting amplification of light photons, noise recorded by the sensors prior to the detection of light photon amplification is either shifted out of the sensor prior to the photon generating event or is smeared across the sensor data. The effects of system noise can be reduced by detecting and removing this smeared sensor data.