The first positron lifetime spectrometer in China was born at our laboratory in 1978 and the high efficient BaF2 detector system was used since 1986 (T.B. Chang). Then the time-selected Energy Spectrometer was developed by combination of the lifetime spectrometer and the HP-Ge Gamma-ray detector. We have just finished a novel 22Na-based positron beam line-the Beijing Slow Positron Beam Line.

Our laboratory have two sets of positron lifetime spectometers and two sets of HP-Ge Gamma-ray energy spectrometers, both the lifetime and Gamma-ray energy spectometers can work under high magnetic field (upto 2T) and/or under low-temperature ranged from 77 K to 500 K. The Beta+-Gamma coincidence positron life spectrometer can work at high temperature upto 1700K.

The research works in this laboratory have been supporting continuously since early 1980s by National Nature Science Foundation of Chine (NNSF) and the Chinese Academy of Science (Academia Sinica). The study on the formation and annihilation behavior of positronium in silica aerogel; the 3gamma-decay energy spectrum and annihilation rate of ortho-positronium; the study on pick-off process of positron annihilation in PTFE have been completed.

Currently, we do some extended work on nuclear physics and applications to materials science. Such as improving the signal-noise ratio to measure the two-garmma annihilation spctrum, finding new methods to study the chemical potential, measuring precisionally of the positronium decay rate in the vacuum and comparing with the theory of QED, investigating the phase separating of polymers and the behavior of positroum in clusters. Studies on surface and interfaces will be done in our slow positron beam line.

The first Mossbauer spectrometer and the first measured spectrum in China was born in this mossbauer laboratory. We have developed many methods of experiment and various of research work have been done in our laboratory.

Dr. Long Wei is responsible for this research group, any suggestions and comments to us are thankful.

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Send mail to positron@ihep.ac.cn with questions or comments. Last modified: June. 23, 2001