KEYWORDS: Single photon, Scintillation, Liquids, Data acquisition, Chemiluminescence, Spectroscopy, Power supplies, Photomultipliers, Computing systems
Liquid Scintillation Counting (LSC) is widely used in measurement of α- and β-emitting. Single photons generated by chemiluminescence affects the accuracy in low-energy β activity measurement. A novel method based on the fall time analysis of Photomultiplier Tube(PMT) output signals was developed to discriminate the single photons. A liquid scintillation measuring system made of a Hamamatsu R9420 Photomultiplier Tube and a Paul Scherrer Institut (PSI) digitizer was used to collect the light emitting from the cocktails. Ultima Gold liquid scintillation cocktails with different concentration of 14C standard solution were measured to verify the feasibility of the method. Effects of the Analog-to-Digital Converter (ADC) sampling frequency on the discrimination of single photons were analyzed. The results show that the signals of single photons and low-energy β emitted from 14C were discriminated at a fall time threshold of 6ns above the ADC sampling frequency of 500MHz.
Light field imaging uses a single camera to capture an array of images from different angles. It can obtain the spatial information and angle information of the light scene by placing a micro-lens array between the lens and the image sensor to, which is widely used in computer vision, industrial inspection, medical imaging. The image depth estimation algorithm affects the spatial resolution of reconstructed images. A convolution neural network algorithm based on Epipolar Image (EPI) was developed and optimized by adjusting the parameters. i.e. learning rate and activation function. The depth information of light field image was predicted with an accuracy of 67.5%. The convolution neural network algorithm effectively improved the efficiency of the depth estimation and realized the 3D image reconstruction.
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