Nuclear Techniques ›› 2018, Vol. 41 ›› Issue (1): 10201-010201.doi: 10.11889/j.0253-3219.2018.hjs.41.010201

• LOW ENERGY ACCELERATOR, RAY AND APPLICATIONS • Previous Articles     Next Articles

Study on the precision of positron lifetime measurements

LI Nan, QI Ning, CHEN Zhiquan, WANG Bo   

  1. Hubei Nuclear Solid Physics Key Laboratory, School of Physics and Technology, Wuhan University, Wuhan 430072, China
  • Received:2017-03-31 Revised:2017-06-05 Online:2018-01-10 Published:2018-01-06
  • Supported by:
    Supported by National Natural Science Foundation of China (No.11475130, No.11575131)

Abstract: Background: The precision of positron lifetime measured in the experiment is of great concern. Purpose: Some typical materials were chosen to repeat the positron lifetime measurements over a long time to assure the precision. Methods: By adjusting the working conditions of the spectrometer, we studied the factors affecting the precision of the measured positron lifetime, such as the time resolution, total count of the lifetime spectrum, number of lifetime components in the sample and also the interval between each lifetime components. Results: It was found that with stable working condition of the spectrometer and a total count of 1 million for each spectrum, the positron bulk lifetime in Si single crystal is about 218 ps, and the standard deviation is only 0.5 ps after several repeated measurements. In poly(methyl methacrylate) (PMMA), where positrons have three lifetime components, the standard deviation of the average lifetime is also only 1 ps, and the standard deviation of the longest lifetime t3 (1.83 ns) is 0.016 ns. Our experiment also shows that the time resolution of the spectrometer has little effect on the measure of positron lifetime. Conclusion: The results indicate the positron lifetime measurement has high precision, and is a reliable tool to detect the change of the microstructure of materials.

Key words: Positron lifetime, Time resolution, Standard deviation, Precision

CLC Number: 

  • TL817+.9