Effects of secondary electron emission yield properties on gain and timing performance of ALD-coated MCP

https://doi.org/10.1016/j.nima.2021.165369Get rights and content

Highlights

  • The dependence of the performance of ALD-coated MCP on the backscattered electron yield was studied.

  • The dependence of the performance of ALD-coated MCP on the rediffused electron yield was studied.

  • High-gain ALD-coated MCP can be obtained in three ways.

Abstract

The technology of atomic layer deposition has been used to improve the lifetime of the microchannel plate-photomultiplier tube (MCP-PMT) effectively and makes MCP possible to choose to coat different potential emissive materials on the internal surface of the MCP channels in the future. However, it is still an open question to what extent the secondary electron emission (SEE) yield properties of the emissive materials influence the behavior of the ALD-coated MCP. In this work, the dependences of the gain and timing performance on the SEE yield properties were assessed by using the Monte Carlo and particle-in-cell methods. We established the three-dimensional MCP single channel model in Computer Simulation Technology (CST) Particle Studio. Three important secondary electron emissions, the backscattered, rediffused and true SEEs, were discussed numerically based on the probabilistic model. The secondary electron cascade processes in the MCP single channel were simulated. The simulation results indicate that the opportunities for improving the gain of the ALD-coated MCP by improving the SEE yields corresponding to the incident energies of 0 eV–100 eV. The backscattered and rediffused electrons are found to have strong effects on the gain and timing performance of the MCP. Although the higher the SEE yield the higher the MCP gain, the drawback is the extremely high SEE yield will make the MCP saturated prematurely and degrade the time resolution. The simulation results will be used to guide the design and selection of emissive material for ALD-coated MCP development.

Introduction

The photomultiplier tube (PMT) based on microchannel plates (MCPs) is a kind of compact high-sensitive photodevice consisting of photocathode, MCPs, anode and tube shell [1], [2]. Due to high sensitivity to single photon, fast time response, high temporal–spatial resolution and magnetic field tolerance, MCP-PMTs have become attractive photodetectors to be exploited in the modern high-energy physics detection systems, such as PANDA DIRC Cherenkov detector [3], [4], the Electron–Ion collider(EIC) [5], Belle II TOP detector [6], inertial confinement fusion (ICF) diagnostics [7], [8] and JUNO neutrino detector [9]. However, the damage caused by the ions feedback in the channel to the photocathode limits the lifetime of the MCP-PMT. To address this problem, the atomic layer deposition (ALD) technique is used innovatively to deposit the novel emissive materials on borosilicate glass substrate instead of the lead-silicate glass used in conventional MCP to improve the lifetime of the MCP-PMT. Researches have shown that the ALD-coated MCP-PMTs have reached a lifetime of >20 C/cm2 integrated anode charge (IAC) compared to the conventional MCP-PMT’s lifetime of <0.2 C/cm2 IAC [10], [11]. Moreover, the ALD technique makes it possible to try coating different emissive materials, such as Al2O3, MgO, MgO/Al2O3 composite, SiO2 and other new potential candidate materials with SEE functions, on the internal surface of the MCP channel [12], [13]. The SEE yield property of the emissive material fluctuates in a wide range as the film thickness, doping ratio, structure design and preparation technology of the material change [14], [15], [16]. It is important to study how the SEE yield property of emissive material affects the behavior of the ALD-coated MCP to provide the guidance for the selection and design of emissive material. However, so far the systematic simulations and experimental studies for various emissive materials are still sparse. In addition, the backscattered and rediffused electrons are often ignored in previous simulation studies due to their small proportions in the total secondary electrons. Thus, fully studying how SEE yield properties affect the behavior of ALD-coated MCP is significant to make predictions of MCP performance and help for choosing the appropriate emissive materials for different application requirements.

In this work, the 3D model of the MCP single channel was built in the Computer Simulation Technology (CST) Particle Studio. The Monte Carlo and particle-in-cell (PIC) methods were used to simulate the secondary electron cascade processes and predict the performance of the ALD-coated MCP with different SEE yield properties within the channel. The main characteristics of the ALD-coated MCP, gain and timing performance, dependent on the backscattered, rediffused and true SEE yield properties of the emissive materials have been evaluated respectively.

Section snippets

3D Model of the MCP single channel

MCP which plays crucial role in the MCP-PMT has a kind of plate-like structure composed of millions of micro channels, which can be regarded as independent electron multipliers. The schematic structure of the MCP is shown in Fig. 1(a). The conventional MCP is made of lead glass, as shown in Fig. 1(b). After hydrogen reduction treatment, the emissive layer will be formed on the inner surface of the channel. However, the significant disadvantage of using this kind of material is that feedback

MCP with conventional lead glass

To verify the accuracy of our simulation model, we first calculated the gain of the MCP with conventional lead glass as the emissive material to compare the numerical results with experimental data at the supply voltage of 1000 V. For the conventional MCP with the lead glass, the maximum total SEE yield δt_max=4 for primary electron energy Emax=260eV is employed in our simulation [19]. The SEE yield as a function of the primary electron energy at normal incidence is shown in Fig. 4. The maximum

Conclusion

In this work, the influences of the SEE yield properties on the gain and timing performance of ALD-coated MCP were numerically investigated by using the Monte Carlo and particle-in-cell (PIC) methods. The simulated gain of 1.46×104 for the MCP with conventional lead glass shows good agreement with the experimental data at the supply voltage of 1000 V which confirms the feasibility of the simulation methods. The dependences of the gain and timing performance on the backscattered, rediffused and

CRediT authorship contribution statement

Lehui Guo: Conception of the study, Writing- original draft. Liwei Xin: Helping to build the three-dimensional model, Methodology. Lili Li: Helping to build the three-dimensional model, Methodology. Yongsheng Gou: Software. Xiaofeng Sai: Software. Shaohui Li: Software. Hulin Liu: Software. Xiangyan Xu: Data curation. Baiyu Liu: Data curation. Guilong Gao: Data curation. Kai He: Analysis of the results. Mingrui Zhang: Analysis of the results. Youshan Qu: Analysis of the results. Yanhua Xue:

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work is supported by National Natural Science Foundation of China (Grant No. 11805267 and 12075311), the Scientific Instrument Developing Project of the Chinese Academy of Sciences (Grant No. GJJSTD20190004), Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA25030900) and Key Laboratory for Laser Plasmas   (Ministry    of  Education),  Shanghai Jiao Tong University, China .

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