Magnetic quenching of positronium studied by positron annihilation lifetime and Doppler broadening measurements
Magnetic quenching of positronium studied by positron annihilation lifetime and Doppler broadening measurements
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通过正电子湮灭寿命和多普勒展宽测量研究正电子的磁淬灭
DOI：
10.1016/j.radphyschem.2020.108712
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发表时间：
2020-06-01
影响因子：
2.9
通讯作者：
Chen, Z. Q.
中科院分区：
文献类型：
--
作者：
Liu, J. D.;Guo, J. Q.;Chen, Z. Q.
用正电子湮没寿命（PAL）和多普勒展宽（DB）方法研究了γ-Al_2O_3纳米粉在静磁场中的湮没。从PAL和DB结果中揭示了Ps原子的四个本征态（垂直条1，1，垂直条1，- 1，+（由于塞曼效应，垂直条1，0和垂直条0，0的长寿命本征态混合），垂直条-（由于塞曼效应，垂直条1，0和垂直条0，0的短寿命本征态混合））的性质.此后，随着磁场从0.105 T增加到0.760 T，观察到Ps湮没参数的明显规律性变化：（1）三个长寿命Ps态的平均寿命（竖条1，1，竖条1，-1，竖条+）表现出明显的淬火效果;（2）每个Ps本征态的形成概率（竖条1，1，竖条1，-1，竖条+，竖条-）保持不变;（3）窄分量的强度DB谱（由多高斯拟合得到）呈现出逐渐增加的趋势，这与PAL结果的理论计算结果相一致（2）垂直条+和垂直条-态的γ衰变，以及长寿命Ps态的拾取猝灭）;（4）DB谱的低能区的强度由于3的降低而减弱。竖条+状态的衰减。磁场与o-Ps湮灭参数之间的定量关系将有助于进一步理解复杂的Ps淬灭效应，如正-对位自旋转换和磁淬灭的混合效应。
Annihilation of positronium (Ps) in static magnetic fields is investigated by positron annihilation lifetime (PAL) and Doppler broadening (DB) measurements of gamma-Al2O3 nanopowder. The properties of four eigenstates of Ps atoms (vertical bar 1,1 , vertical bar 1, - 1 , + (long-lived eigenstate mixed from vertical bar 1,0 and vertical bar 0,0 vertical bar due to Zeeman effect), and vertical bar - (short-lived eigenstate mixed from vertical bar 1,0 and vertical bar 0,0 due to Zeeman effect)) were revealed from PAL and DB results. Thereafter, with magnetic field increasing from 0.105 to 0.760 T, clear and regular variation of Ps annihilation parameters are observed: (1) The mean lifetime of the three long-lived Ps states (vertical bar 1,1 , vertical bar 1, -1 , and vertical bar + ) shows clear quenching effect; (2) The formation probability of each Ps eigenstate (vertical bar 1,1 , vertical bar 1, -1 , vertical bar + , and vertical bar - ) keeps unchanged; (3) The intensity of the narrow component (derived from multi-Gaussian fitting) of DB spectrum exhibits a gradual increase which is in good agreement with the theoretical calculation from PAL results (2 gamma decay of vertical bar + and vertical bar - states, and pick-off quenching of long-lived Ps states); (4) The intensity of the low energy region of DB spectrum is diminished by the decrease of 3. decay of vertical bar + state. The quantitative correlations between magnetic field and o-Ps annihilation parameters will be helpful for the further understanding of complex Ps quenching effects, such as the effect mixed from orhto-para spin conversion and magnetic quenching.