Superallowed Fermi beta decay

在粒子物理学的领域里，在亚微观尺度上对自然的描述已经演变成所谓的标准模型。这是一套规则，它规定了我们宇宙的基本组成部分和作用于它们之间的力。在ISAC，正在进行放射性同位素衰变的研究，以便更好地了解自然界中的这些基本力量。大多数放射性同位素的衰变是通过同时发射两种高能粒子——β（即电子）和中微子。我们目前对弱相互作用（引起核衰变的力）的理解预测，对于极少数特殊的同位素，衰变性质应该是相同的，并且以一种简单的方式与弱力的矢量分量相关。对这些所谓的超允许费米衰变的衰减率的精确测量可以用来检验这一假设，并确定力的强度。目前世界上关于超允许费米衰变的数据得出了一个结果，为标准模型提供了最精确的测试之一。然而，这个结果也依赖于在应用测试之前必须计算的小但非常重要的修正。TRIUMF-ISAC设施提供这些特殊放射性同位素的光束，其质量范围比以前更大。这允许我们进一步测试模型并验证必须应用的更正。

Within the realm of particle physics the description of nature on the submicroscopic scale has evolved into the so-called Standard Model. This is a set of rules which specifies the basic constituents of our Universe and the forces that act between them. At ISAC, studies of the decay of radioactive isotopes are being pursued to obtain a better understanding of these fundamental forces in nature. Most radioactive isotopes decay by the simultaneous emission of two energetic particles a beta (i.e. an electron) and a neutrino. Our present understanding of the weak interaction (the force that causes nuclear beta decay) predicts that for a very few special isotopes the decay properties should be identical and related in a simple way to the vector component of the weak force. Precision measurements of the decay rate for these so-called superallowed Fermi beta decays can be used to test this hypothesis and to determine the strength of the force. The current world data on superallowed Fermi beta decay leads to a result that provides one of the most precise tests of the Standard model. However, this result also depends on small but very important corrections that must be computed before the test can be applied. The TRIUMF-ISAC facility provides beams of these special radioactive isotopes over a wider mass range than was previously available. This allows us to further test the model and to validate the corrections that must be applied.