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Microchannel plates (MCPs) are widely utilized as key device components in various photomultipliers; however, the performance of MCPs cannot be further improved by traditional processing. Atomic layer deposition (ALD) is a promising route to prepare a composite conductive layer and secondary electron emission (SEE) layer structure on the inner wall of the MCP. Moreover, ZnO is an essential component of a composite conductive layer, which is located at the bottom of the SEE layer and significantly influences the SEE coefficient, which, in turn, affects the gain performance of MCPs. Herein, ALD is used to deposit different thicknesses of ZnO films (1–50 nm) on an Si substrate, resulting in an ZnO/Si double-layer film structure. The relationship between the SEE coefficient and the primary electron energy of ZnO films with different thicknesses was established. The maximum secondary electron yield value of 2.04 is achieved at a film thickness of 30 nm. Moreover, Dionne's SEE model and theory of semiconductors are used to simulate and verify the experimental results. These results provide useful guidelines for the development of ALD-MCPs. [ABSTRACT FROM AUTHOR]

As a secondary electron emission layer, an Al 2 O 3 /MgO double-layer structure is fabricated by atomic layer deposition (ALD) technology. The thickness range from 1 nm to 4 nm of the top Al 2 O 3 layer deposited on 20 nm MgO creates a double-layer. The morphology of the cross section, element distribution, surface roughness, X-ray diffraction, and secondary electron yield (SEY) values were measured by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM) and secondary electron emission (SEE) measurement systems. The SEE characteristics of the MgO single layer, Al 2 O 3 single layer and MgO/Al 2 O 3 double-layer were measured. The maximum SEY of a single MgO layer reached 6.2@600 eV, and the maximum SEY of a single Al 2 O 3 layer reached 3.92@400 eV. The SEY of the Al 2 O 3 /MgO double-layer decreased when the Al 2 O 3 thickness ranged from 1 nm to 4 nm, and the SEY reduction value of the double-layer decreased as the Al 2 O 3 thickness increased. Finally, Dionne's semiempirical SEE model was employed to explain the SEE yield of the prepared composite film structures. These results are useful for depositing a secondary electron emission layer in the channel of microchannel plates. [ABSTRACT FROM AUTHOR]

Secondary electron emission (SEE) plays a crucial role in the gain performance of devices, such as electron multipliers and microchannel plates (MCPs). Gain performance could be improved by increasing the secondary electron yield (SEY) of device surface. Al2O3 coating is an ideal material for SEE, benefiting from its high SEY. The Al2O3 coating deposited on inner device walls by atomic layer deposition (ALD) can improve the gain performance of devices. In this study, the SEE characteristics of Al2O3 coatings were investigated experimentally. A series of Al2O3 coatings with thicknesses of 1-30 nm were prepared on Si substrate through the ALD method. Then, the SEY of the coatings were quantified as a function of primary electron energy in the range of 100∼1500 eV. Furthermore, an equation describing the true SEY as a function of thickness was established by applying theory of Dionne's SEE model. This work presents potential approach for controlling the SEE level of Al2O3 coatings through thickness adjustment and is crucial for comprehending the SEE of composite materials. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A three-dimensional numerical model developed based on the finite element method to simulate the position-reconstruction performance of multilayer capacitive anodes is presented. The charge collection efficiency and position nonlinearity are calculated for different electrode layers, patterns, and sizes, as well as the distance between the bottom microchannel plate (MCP) and induction layer. The position nonlinearity exhibits an approximately linear relationship with the electrode size and the distance between the bottom MCP and induction layer. By increasing the electrode area in the perimeter region and designing 2.2 mm square electrodes in the central region, a position nonlinearity of 3.36% with a distance of 5 mm between the bottom MCP and induction layer is achieved. The imaging performance of the six multilayer capacitive anodes is evaluated using a custom-designed detector prototype, and the experimental results validate the simulation results. The comprehensively optimized capacitive anode shows an imaging nonlinearity of 0.91% in the experiment. [ABSTRACT FROM AUTHOR]

In this paper, we propose a hermetically sealed X-ray microchannel plate imager as a more effective and stable alternative to the traditional open-structured imager. With two microstrip photocathodes of 100 nm Au and 100 nm CsI, respectively, the proposed imager has a measured exposure time of 65 ps when applied with a 200 ps width gate pulse. The static response test shows that the image intensity of the CsI microstrip photocathode is 3.4 times that of the Au microstrip photocathode when illuminated by a non-monochromatic portable X-ray source with high energy photons. The sealed imager not only enhances the sensitivity and stability of the framing camera, but also has the potential to reduce crosstalks and artifacts, thus further improves the precision of measurement in practice. • Image intensity of CsI microstrip is 3.4 times that of Au microstrip. • Measurement stability can be improved via hermetically sealed structure. • Sealed MCP imager has potential to reduce crosstalks and artifacts. [ABSTRACT FROM AUTHOR]