Position linearity analysis of circular arc terminated resistive anode using finite element method for photon-counting imaging detectors.

This study proposes a comprehensive model of the circular arc terminated (CAT) resistive anode based on the finite element method to explore the dynamic process of charge diffusion on this anode and its position linearity performance. The waveforms of charges of the electrodes on the anode are calculated for different electrical parameters and their influence on positional linearity is investigated. The influence of the signal development time and the non-uniformity of the resistance per square of the anode on positional linearity is also analyzed. The results of simulations show that the non-linearity of the image varies monotonically with the termination resistance and the non-uniformity of the resistance per square of the anode, but has a non-linear relationship with the signal development time and the ratio of the resistance per square. A CAT resistive anode with capacitance c and a resistance per square of the sensitive area of R▱ can be used to recover an image with a root mean-squared non-linearity of 2%, when the charge signals of the electrode are collected for at least 0.6R▱c s. The reliability of the results of the simulations was verified with experimental measurements.

High-Sensitivity and Long-Life Microchannel Plate Processed by Atomic Layer Deposition.

As a key component of electron multiplier device, a microchannel plate (MCP) can be applied in many scientific fields. Pure aluminum oxide (Al2O3) as secondary electron emission (SEE) layer were deposited in the pores of MCP via atomic layer deposition (ALD) to overcome problems such as high dark current and low lifetime which often occur on traditional MCP. In this paper, we systematically investigate the morphology, element distribution, and structure of samples by scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS), respectively. Output current of different thickness of Al2O3 was studied and an optimal thickness was found. Experimental tests show that the average gain of ALD-MCP was nearly five times better than that of traditional MCP, and the ALD-MCP showed better sensitivity and longer lifetime.

Three-dimensional reconstruction of laser-imploded targets from simulated pinhole images.

This paper proposes an integral method to achieve a more accurate weighting matrix that makes very positive contributions to the image reconstruction in inertial confinement fusion research. Standard algebraic reconstruction techniques with a positivity constraint included are utilized. The final normalized mean-square error between the simulated and reconstructed projection images is 0.000365%, which is a nearly perfect result, indicating that the weighting matrix is very important. Compared with the error between the simulated and reconstructed phantoms, which is 2.35%, it seems that the improvement of the accuracy of the projection image does not mean the improvement of the phantom. The proposed method can reconstruct a simulated laser-imploded target consisting of 100×100×100 voxels.

[Research on the method of transient spectrum detection based on array CCD].

Based on the characteristic of high speed line scanning for CCD in transient spectrum detection, a method of transient spectrum detection with array CCD is presented. The high speed line scanning with array CCD was realized by changing the mode of charge transfer. In order to explore the feasibility of this method, a fast detection system of single point based on linear CCD was designed and fabricated. Seven different LED pulses were measured when the system worked at fast detection mode of single point and normal mode respectively. The results demonstrate that the method of fast detection of single point based on linear CCD is feasible, and the rate of single point detection reaches up to 20 MHz. Thus, in theory, it was proved that transient spectrum detection with array CCD by changing the mode of charge transfer is also feasible.

[Real-time measurement of detonation transient temperature].

Based on the spectral characteristic of the detonation temperature, the present paper presents a measurement system of transient multi-wavelength pyrometry with the theory of multi-wavelength thermometry. The FPGA was applied as the hardware developing platform and the high-speed linear CCD was utilized. Each module was controlled by FPGA to achieve the process of real-time data acquisition, storage and transmission. Using the multiple regression analysis method, the dynamic spectral waveforms were calculated. The two laser spectral lines, 630 and 532 nm, were used to calibrate the corresponding pixel sequence numbers and the No. 175 and No. 270 were confirmed. In this paper, the halide tungsten light was measured. The results show that the system can sample continuous spectrum signal at several different times; the CCD can stably work with 40 MHz clock and the frame scanning frequency can achieve 73 kHz.