In the standard model of elementary particle physics neutrinos are massless, and therefore the actuality of finite neutrino mass indicates a theory beyond the standard model. The Sun produces abundant neutrinos due to nuclear fusion reactions. A pioneering experiment in the early '70s detected neutrinos from the Sun, but found that the observed flux was smaller than expected, which was then called the missing solar neutrino problem. Tremendous efforts were made both experimentally and theoretically to solve this problem. In 2001, almost 30 years after the first indication, data from Super-Kamiokande in Japan and SNO in Canada together provided evidence that neutrino oscillation effectively converts the solar (electron) neutrinos to non-electron type neutrinos. Neutrino oscillation can occur only for those neutrinos with finite neutrino mass.

中文翻译：

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太阳、中微子和超级神冈。


在基本粒子物理的标准模型中，中微子是无质量的，因此中微子质量有限的现实表明了一种超出标准模型的理论。由于核聚变反应，太阳产生大量的中微子。七十年代初期的一项开创性实验检测到了来自太阳的中微子，但发现观测到的通量比预期要小，这在当时被称为太阳中微子缺失问题。为了解决这个问题，人们在实验和理论上做出了巨大的努力。 2001年，距离首次发现近30年后，日本超级神冈探测器和加拿大SNO的数据共同提供了中微子振荡有效地将太阳型（电子）中微子转化为非电子型中微子的证据。中微子振荡只有那些中微子质量有限的中微子才会发生。