Research in Nuclear Astrophysics, Nuclear Physics, and Particle Physics

NSF的这笔拨款旨在支持三个主要项目，所有这些项目都旨在了解超新星或x射线爆发，这两个事件是宇宙中最戏剧性的事件。前两项将研究对恒星过程至关重要的原子核或核反应，恒星合成了构成我们宇宙的许多原子核。这两个过程都涉及到异常炎热的恒星环境，这导致这些过程以非常快的速度进行。因此，它们可以在一种情况下添加许多质子，或者在另一种情况下添加中子，而不经历通常保持原子核稳定或接近稳定的衰变。理解这些过程需要知道它们通过的原子核的性质和反应，所以这两个程序都专注于短寿命的原子核。这些核只能在放射性核束设施中产生，这就需要我们在密歇根州立大学、加拿大TRIUMF或日本理研的加速器实验室工作。很好地理解核合成过程的核方面，最终可以反演预测的核丰度，以了解或约束发生这些过程的恒星环境。因此，这两个方案旨在了解这些过程中的核合成以及这些过程运行的条件。这项研究的大部分将产生核天体物理学和核物理学都感兴趣的数据。第三个项目是开发一个星系超新星发射的中微子天文台。虽然这最终将是一项比目前拨款所能支持的更大的努力，但我们计划在未来三年内进行计算并开发对这个天文台至关重要的探测器。来自超新星的中微子预计将在几十秒内到达地球，在此期间，我们应该能够获得大量关于恒星坍塌过程的诊断信息，以及随后伴随着超新星爆炸及其核心塌缩为中子星或黑洞的事件。也有可能使用这些数据来确定最大质量的中微子的质量，这些信息对天体物理和粒子物理的其他领域非常有用。

This NSF grant is intended to support three main programs, all aimed at understanding supernovae or x-ray bursts, two of the most dramatic events in the cosmos. The first two will study nuclei or nuclear reactions that are important to processes in stars that synthesize many of the nuclei of which our universe is comprised. Both processes involve unusually hot stellar environments, which result in the processes proceeding at very rapid rates. Thus they can add many protons, in one case, or neutrons, in the other, without undergoing the decays that usually maintain nuclei at or near stability. Understanding these processes necessitates knowing the properties of, and reactions on, the nuclei through which they pass, so both of these programs focus on short-lived nuclei. These nuclei can only be produced at radioactive nuclear beam facilities, necessitating our working at accelerator laboratories at Michigan State University, TRIUMF in Canada, or RIKEN in Japan. A good understanding of the nuclear aspects of the processes by which nuclei are synthesized ultimately allows inversion of the predicted nuclear abundances to understand or constrain the stellar environments in which these processes occur. Thus these two programs are aimed at understanding both the nucleosynthesis from these processes and the conditions in which the processes operate. Much of this research will produce data of interest to both nuclear astrophysics and nuclear physics.The third project is for development of an observatory of neutrinos emitted from a galactic supernova. While this will ultimately be a much larger effort than could be supported by the present grant, we plan over the next three years to perform the calculations and develop the detectors that will be essential for this observatory. The neutrinos from a supernova are expected to arrive at earth in several tens of seconds, during which time we should be able to obtain an extraordinary amount of diagnostic information about the process of stellar collapse and the ensuing events that accompany the explosion of a supernova and the collapse of its core to a neutron star or black hole. It may also be possible to use the data to determine the mass of the most massive neutrinos, information that would be extremely useful to other areas of astrophysics and to particle physics.