| The pulsed slow-positron beam device is one of the most advanced experimental technology of positron annihilation. Comparing to the normal slow positron beam device, a time signal can also be obtained from the pulsed system, so, the pulsed slow-positron beam apparatus can be used to studying the positron lifetime of thin-film materials and to research the surface of many other materials. Besides, it can be served as a platform, because based on the system, the two-dimensional positron annihilation lifetime spectrometer (2D-PALS), age-momentum correlation spectroscopy (AMOCS), positronium time-of-flight measurement (Ps-TOF) and some other new type positron annihilation experimental apparatus can be installed. Our designation of the pulsed slow-positron beams is the first model in our nation. It has a serious significant for future researching work.In this article, we first introduce the normal positron annihilation experimental technologies and the history of the slow-positron beam and the pulsed slow-positron beam.Next, we introduce the details of the design of this apparatus. This apparatus is mainly composed of the radioactive source, moderator, chopper, pre-buncher, main-buncher, accelerator rings and Faraday cup. The radioactive source is 50mCi22Na, moderator is designed as a transmission structure with W meshes. The pulsed system consists of a chopper, a pre-buncher and a main-buncher. The chopper is designed as a reflection type structure, which consists of three W meshes, the chopper signal is applied to the second mesh. The pre-buncher is designed as a coaxial resonator with a frequency tuner which can tune frequency in a small range. The main-buncher is also designed as a coaxial resonator. We measure their resonance frequency with Network Analyzer, and the results, which pre-buncher's resonance frequency can be tuned in the range of 48.947744MHz-51.927436MHz and the main-buncher's resonance frequency is 201.402581MHz, approximately accord with the simulation result by MAFIA. Finally, the incident positron energy is variable from 0.5 to 30keV, and the positron pulse is compressed to≤200ps at the sample position.Following above, we introduce the designation of the vacuum system. Using the mechanical pump and the molecular pump as the fore pump to pre-pump vacuum, after the degree of vacuum is come up to about 5×10-3Pa, another two ion pumps are used so that we can obtain a better degree of vacuum, a degree of about 5×10-6 Pa could be achieved at last.The electronic control system is designed to have signal generation subsystem and time-measurement subsystem. The beam pulsing subsystem generates three beam pulsing signals to chop and buncher the beam; at the same time, the signal generation subsystem also supply a synchronous time signal of the chopper as the ending time signal for the time-measurement subsystem, while the time-measurement subsystem measures the time interval of the "start" time signal which comes from the photomultiplier tube(PMT) and "end" time signal which comes from the signal generation subsystem. In addition, we take many electronic tests for those subsystems.Besides, the designation of the ground-wire subsystem is also introduced in details, it adopts the so called two-ground-wire design proposal.At last, we introduce the simulation calculation about the spatial focusing and the time focusing of the slow positron beams and the debug of the corresponding subsystems. After many debugs, we find the result of the spatial focusing is good, but, because of the large noisy signals, the time focusing process is hard to debug.
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