Neutrino Astrophysics

在二十世纪末，在所有突出的天体物理问题中，都有“太阳中微子问题”。这个问题是指与太阳理论内部模型预期的中微子产生速度相比，太阳中微子产生的测量速度较低。由于中微子产生的速率与太阳的热核能速率成正比，人们对证实我们对太阳发光原因的基本理解非常感兴趣。观测到的速度和预测的速度之间的差异使人们对这种理解产生了疑问，因此有了“太阳中微子问题”这一术语。首席研究员(PI)建议将他在苏联巴克扬中微子实验室的苏联-美国镓实验(SAGE)的工作延续三年。这项实验将对太阳内部和中微子理论提供迄今最灵敏的测试，因为它对低能量和中能中微子敏感，而现有的实验(在日本的霍米斯塔克、南达科他州和神冈德)对由侧核反应产生的相对较少的高能中微子敏感。SAGE实验于1990年初投入使用，并已经产生了令人兴奋的结果，与理论预测相比，中微子极其匮乏。如果未来用更灵敏的设备对太阳的监测证实了这些早期的结果，那么要么我们对太阳内部结构的理解，要么是中微子的基本性质必须改变。在SAGE实验中，PI在构造正比计数器探测器中起到了至关重要的作用。PI建议继续发挥这一作用，这既是因为旧的探测器随着时间的推移而恶化，也是因为更多的探测器将提供对中微子差异的更灵敏的测试。此外，这些探测器提供了一种区分真正的太阳中微子和由地球上交替过程产生的中微子的方法。因此，PI的努力将有助于确定中微子差异的程度，从而导致更早的解决方案。

On every list of outstanding astrophysical problems in the late twentieth century is the "solar neutrino problem." This problem refers to the measured low rate of neutrino production in the Sun compared to rates expected from theoretical interior models of the Sun. Since the rate of neutrinos generated is proportional to the thermonuclear energy rate in the Sun, there is a keen interest to confirm our basic understanding of what makes the Sun shine. The discrepancy between the observed and predicted rate calls this understanding into question, hence the term "solar neutrino problem." The Principal Investigator (PI) proposes a three-year continuation of his work in the Soviet-American Gallium Experiment (SAGE) located in the Bakyan Neutrino Laboratory in the Soviet Union. This experiment will provide the most sensitive test yet of solar interior and neutrino theories because it is sensitive to low and moderate energy neutrinos, whereas existing experiments (at Homestake, South Dakota and Kamiokande in Japan) are sensitive to the relatively few high energy neutrinos produced by side-nuclear reactions. The SAGE experiment became operational in early 1990 and has already produced exciting results, an extreme dearth of neutrinos relative to the theoretical predictions. If future monitoring of the Sun with more sensitive equipment confirms these early results, then either our understanding of the Sun's interior structure or the fundamental nature of neutrinos must be changed. The PI has played a vital role in constructing the proportional counter detectors for the SAGE experiment. The PI proposes to continue this role both because the old detectors deteriorate with time and also because more detectors will provide a more sensitive test of the neutrino discrepancy. In addition, these detectors provide a means of discriminating between bonafide solar neutrinos and neutrinos produced by alternate processes on the Earth. Thus, the PI's efforts will help to define the extent of the neutrino discrepancy, leading to its earlier resolution.