在J-PARC上用脉冲中子束精确测量中子寿命
Precise Neutron Lifetime Measurement Using Pulsed Neutron Beams at J-PARC
摘要：
中子通过β衰变过程衰变为质子、电子和反中微子。衰变寿命（$\sim$ 880 s）是弱相互作用中的一个重要参数。例如，中子寿命是用于确定中子能量的参数。|$V_{\rm ud}$| CKM夸克混合矩阵的参数。寿命也是大爆炸核合成的输入参数之一，它预测了早期宇宙中轻元素的合成。然而，实验测量的中子寿命今天是显着不同的（8.4秒或4.0 $σ$）取决于方法。一种是测量中子储存瓶中剩余中子的瓶法。另一种是束流法，测量中子束流通量和中子在探测器中的衰变率。有一种讨论认为，差异来自未考虑的系统误差或不可检测的衰变模式，如暗衰变。在BL 05 MLF J-PARC上进行了一种新型的束流实验。该实验使用脉冲中子束，利用时间投影室同时测量中子通量和衰变率。我们将在J-PARC上介绍中子寿命的世界情况和最新结果。
英文摘要：
A neutron decays into a proton, an electron, and an anti-neutrino through the beta-decay process. The decay lifetime ($\sim$880 s) is an important parameter in the weak interaction. For example, the neutron lifetime is a parameter used to determine the |$V_{\rm ud}$| parameter of the CKM quark mixing matrix. The lifetime is also one of the input parameters for the Big Bang Nucleosynthesis, which predicts light element synthesis in the early universe. However, experimental measurements of the neutron lifetime today are significantly different (8.4 s or 4.0$σ$) depending on the methods. One is a bottle method measuring surviving neutron in the neutron storage bottle. The other is a beam method measuring neutron beam flux and neutron decay rate in the detector. There is a discussion that the discrepancy comes from unconsidered systematic error or undetectable decay mode, such as dark decay. A new type of beam experiment is performed at the BL05 MLF J-PARC. This experiment measured neutron flux and decay rate simultaneously with a time projection chamber using a pulsed neutron beam. We will present the world situation of neutron lifetime and the latest results at J-PARC.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
