Abstract:
Background Typically, radiation detectors require an additional coupled scintillator layer to convert incident radiation rays into optical signals, which are then received by the detector. Compared to other types of glass, lead fluoride (PbF2) glass has a high refractive index, and when electrons pass through a lead fluoride crystal, they generate Cherenkov light. As a result, lead fluoride itself can function as a scintillator.
Purpose Using a lead fluoride crystal as the optical window of a detector enables it to both generate and detect light. This optimizes the optical transmission and detection performance, shortens the conversion time from the reaction medium to photons, improves the detector’s efficiency, and provides an experimental foundation for future applications in ultrafast detection.
Methods After cleaning components such as the cathode input window, ceramic parts, and anode of the photomultiplier tube, a transition indium sealing film layer is deposited on the cathode input window. The ceramic and metal components are then sealed and assembled into a tube shell using a hydrogen furnace. Indium sealing solder is melted into the tube shell’s indium sealing groove, and the tube shell is laser-welded to the anode. The processed tube shell, microchannel plate (MCP), and anode are assembled according to the designed structure. After assembly, the tube shell components and cathode window are mounted on a transfer-type cathode activation and exhaust station. Cathode activation and MCP electron scrubbing processes are then performed. Upon completion of these steps, the tube shell and cathode window are sealed together using indium sealing, resulting in the fabrication of an MCP-type photomultiplier tube bare tube.
Results Two PbF2-window MCP-PMTs were successfully prepared, and their electrical performance, including quantum efficiency and operating voltage, can be measured.
Conclusions By integrating lead fluoride crystals, fast-time-response microchannel plates, and a fast-time coaxial conical anode, this study has successfully addressed key technical challenges in the preparation of lead fluoride crystals as the optical window for photomultiplier tubes. Post-fabrication performance tests indicate that core parameters such as quantum efficiency, gain, and rise time are generally comparable to those of conventional fast-time-response MCP-PMTs.
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