Duan Hui, Liu Fuyan, Zhang Hongqiang, Kuang Peng, Zhang Rengang, Zhang Peng, Yu Runsheng, Cao Xingzhong, Wang Baoyi, Zhang Yubao
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China; Wuhan University of Science and Technology, Wuhan, 430081, China.
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China.
Appl Radiat Isot. 2024 Oct;212:111459. doi: 10.1016/j.apradiso.2024.111459. Epub 2024 Jul 29.
Investigating the mechanism of positron annihilation in liquid-scintillator based neutrino experiments could be helpful for positron reconstruction algorithms and positron-electron discrimination analysis. Based on this, we utilize a novel positron annihilation lifetime spectrometer to characterize a series of liquid scintillator samples without direct contact with the positron source by applying the anti-coincidence method, which facilitates the measurement of liquids with high accuracy and low background. We obtain an ortho-positronium (o-Ps) lifetime value of 3.02 ns for liquid scintillators composed of linear alkylbenzene and two solutes, and we also measure liquid scintillator samples by bubbling different gases to study the interaction of oxygen dissolved with positronium. The discussion of the annihilation behavior of o-Ps in liquid scintillators further clarify the factors affecting the lifetime and intensity of o-Ps, and the calculation of annihilation rate and free volume radius within the samples has potential applications in characterizing gas solubility and free volume in liquids with o-Ps as probe.
研究基于液体闪烁体的中微子实验中的正电子湮灭机制，可能有助于正电子重建算法和正电子-电子鉴别分析。基于此，我们利用一种新型正电子湮灭寿命谱仪，通过应用反符合方法来表征一系列液体闪烁体样品，而无需与正电子源直接接触，这有助于高精度、低本底地测量液体。对于由线性烷基苯和两种溶质组成的液体闪烁体，我们获得了3.02纳秒的正电子素（o-Ps）寿命值，并且我们还通过向液体闪烁体样品中鼓入不同气体来研究溶解氧与正电子素的相互作用。对液体闪烁体中o-Ps湮灭行为的讨论进一步阐明了影响o-Ps寿命和强度的因素，并且以o-Ps为探针计算样品中的湮灭率和自由体积半径在表征液体中的气体溶解度和自由体积方面具有潜在应用。
