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Positron annihilation lifetime spectrometer

A technology of positron annihilation and lifetime, which is applied in the direction of material analysis using radiation, etc., can solve the problems of signal mixing into the signal stop channel and life spectrometer not working normally, and achieve fast time response, lower background, and good energy resolution Effect

Inactive Publication Date: 2007-08-08
TSINGHUA UNIV
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Problems solved by technology

[0009] The most commonly used detector in positron annihilation lifetime spectrometer, BaF 2 Scintillator detector as an example, BaF 2 The energy resolution of the detector to 0.511MeV gamma rays is about 14%, that is, about 72keV. If the radioactive sample itself contains a gamma ray source with energy between 475KeV and 547KeV, the signal will be seriously mixed into the signal stop channel, resulting in The life spectrometer is not working properly

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Embodiment Construction

[0019] Fig. 1 is a schematic diagram of the overall structure of the positron annihilation lifetime spectrometer provided by the present invention. The spectrometer includes two detectors of start track and stop track, fast coincidence time spectrometer and multi-channel pulse amplitude analyzer of microcomputer. Each detector is coupled by lanthanum chloride scintillator 1 and photomultiplier tube 2. The power supplies the high voltage required for the photomultiplier tube to work. The fast coincidence time spectrometer comprises a fast coincidence circuit, a constant-ratio timing discriminator with an energy window of a start track, a constant-ratio timing discriminator with an energy window of a stop track, and a time-amplitude converter. Lanthanum chloride crystal is a new type of scintillation crystal discovered in the world around 2000. It not only has a fast time response, but also has relatively high energy resolution. According to international reports, Φ25×25mm lanth...

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Abstract

It is a positron annihilation lifetime spectroscopy measurement spectrometer, which is characteristic of the positron annihilation lifetime spectroscopy using lanthanum chloride crystals as the scintillator detector. The lanthanum chloride crystals not only have fast response time, but also have more superior energy resolution than the BaF2 crystals. Therefore, it can use the energy window to select circuit, and restrict the signals from the start and stop road detectors in a very narrow energy range, and it can effectively exclude the effect of gamma radiation on the measurement process of other sources (sample materials, environment, etc.), greatly reducing the lifetime spectrum ending, and it enables the spectrometer detector to maintain fast response time, and meanwhile has better energy resolution, which can process the positron annihilation lifetime spectroscopy measurement under the strong gamma-ray interfere, in order to extract positron annihilation lifetime spectroscopy effective information.

Description

technical field [0001] The invention relates to a positron annihilation lifetime spectrometer (Positron Annihilation Lifetime Spectrometer), in particular to a positron annihilation lifetime spectrometer which adopts a novel lanthanum chloride crystal as a scintillator and can resist strong gamma radiation interference. Background technique [0002] After years of rapid development, positron annihilation technology has become a mature technology widely used in the fields of solid state physics, metal physics and material science. The positron annihilation technique has many advantages. It is a non-destructive research method in itself and does not require specially prepared samples. And because the information obtained from the experiment is carried by the annihilation gamma radiation with strong penetrating ability, it is very easy to be used for on-site and in-situ research. [0003] The time elapsed from when a positron is injected into a material to when it annihilates ...

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Application Information

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IPC IPC(8): G01N23/06
Inventor 何元金陈向林赖新春申亮高鑫
Owner TSINGHUA UNIV
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