排序方式: 共有40条查询结果,搜索用时 15 毫秒
1.
A new slow pulsed positron beam, including a positron source, a moderator, a chopper, a pre-buncher, a main-buncher and a sample chamber, etc, has been installed and tested. It is necessary to simulate the acceleration, transportation and space focusing of positrons to meet the needs of beam debugging and further positron annihilation experiments. The result from SIMION simulations shows that the radius of the focused positron beam is less than 5 mm, which is further confirmed in our practical debugging process. 相似文献
2.
3.
4.
本文对Michigan大学S.Hatamian等人在“微波共振跃迁法测量电子偶素2~3S_1-2~3P_J精细结构”实验中所用拟合公式进行了审慎的分析和推证,修正了该公式的功率增宽项,并就Mainz大学R.Ley等人对该公式的批评作了评价。最后,采用新、旧拟合公式对Michigan组实验数据进行拟合并讨论其结果。 相似文献
5.
6.
7.
测量了磁性纳米Fe3O4颗粒的X射线衍射谱(XRD)、正电子湮没寿命谱(PALS)和符合多普勒展宽谱(CDBS),研究了不同压力和退火温度对磁性纳米Fe3O4颗粒物相、电子结构、缺陷及电子动量分布等的影响. XRD,PALS,CDBS测量结果表明:纳米Fe3O4颗粒的缺陷浓度随压力的增加而增大,但物相和缺陷类型并未发生变化;磁性纳米Fe3O4<
关键词:
正电子
3O4')" href="#">Fe3O4
寿命谱
多普勒展宽谱 相似文献
8.
9.
10.
<正>This paper studies the evolution of native point defects with temperature in ZnO single crystals by positron lifetime and coincidence Doppler broadening(CDB) spectroscopy,combined with the calculated results of positron lifetime and electron momentum distribution.The calculated and experimental results of the positron lifetime in ZnO bulk ensure the presence of zinc monovacancy,and zinc monovacancy concentration begins to decrease above 600℃annealing treatment.CDB is an effective method to distinguish the elemental species,here we combine this technique with calculated electron momentum distribution to determine the oxygen vacancies,which do not trap positrons due to their positive charge.The CDB spectra show that oxygen vacancies do not appear until 600°C annealing treatment, and increase with the increase of annealing temperature.This study supports the idea that green luminescence has a close relation with oxygen vacancies. 相似文献