Astroparticle Physics with MILAGRO

超高能伽马射线为研究宇宙射线的相对论高能天体物理源提供了重要工具，这些宇宙射线在我们的银河系和宇宙中被加速到非常高的能量。当高能宇宙射线与物质、磁场和周围的光子相互作用时，它们会产生高能伽马射线和/或高能中微子。其中一些中性粒子直接旅行到地球，当用伽马射线望远镜观察时，不仅可以提供关于宇宙射线的起源和分布及其来源的基本信息，还可以用作探测暗物质湮灭所产生的伽马射线的探测器。因此，它们允许研究基础高能天体物理和粒子物理。由于这些高能伽马射线的流量很小，具有良好指向和足够的宇宙射线抑制能力的大型可接受探测器对这项研究至关重要。Milagro探测器使用一种新技术来探测高能伽马射线。它允许同时和连续地查看TeV能量域中的整个头顶天空。它探测高能伽马射线在大气中相互作用产生的高能粒子束，这就像是每个高能光子的放大器。探测是通过对这些相对论粒子在一个600万加仑的水箱中产生的光光子进行采样进行的，水箱中装有737个光电倍增管。这些光子的脉冲高度和到达时间允许重建原始粒子的天体方向，以及排除大多数不需要的宇宙射线阵雨。它的连续运行允许观察稳定和瞬变TeV伽马射线源。Milagro探测和测量了来自Crab Neubla的伽马射线能谱；来自活动星系核(AGN)处于活动期的耀斑MRK 501和421的伽马射线能谱；来自伽马射线暴(GRB)的伽马射线能谱；以及来自星系盘内宇宙射线与星系盘中物质相互作用产生的弥漫TeV伽马射线辐射，以及来自星系天鹅座臂的TeV伽马射线源的伽马射线能谱。这些观测为理解宇宙线的起源、加速和传播提供了新的重要数据。根据NSF的这项拨款，将继续完善这些和其他可能的对象的观测结果，并分析数据。米拉格罗实验和数据为本科生的研究经验和研究生的硬件和软件培训提供了良好的培训基础。UCI也有几个积极的项目，如COSMOS和Quarknet，以扩大K-12教师和学生的范围。我们一直参与与K-12级别的学生和高年级学生(继续终身学习学院)的沟通。

Very high energy gamma rays provide an important tool to investigate relativistic energetic astrophysical sources of the ubiquitous cosmic rays which are accelerated in our galaxy and in the universe to very high energies. When high energy cosmic rays interact with matter, magnetic fields and ambient photons they generate high energy gamma rays and/or neutrinos of high energy. Some of these neutral particles travel directly to the earth and, when observed by gamma ray telescopes, can both provide essential information about not only the origin and distribution of cosmic rays and their sources, but also can serve as probes for gamma rays expected from the annihilation of dark matter. Thus they allow the study fundamental high energy astrophysics as well as particle physics. As the flux of these high energy gamma rays is small, large acceptance detectors with good pointing and adequate cosmic ray rejection capabilities are essential for this study. The Milagro detector uses a new technique to detect high energy gamma rays. It allows the simultaneous and continuous viewing of the entire overhead sky in the TeV energy domain. It detects the bundles of energetic particles produced by high energy gamma ray interacting in the atmosphere, which acts like an amplifier of each high energy photon. Detection occurs by sampling light photons produced by these relativistic particles in a 6 million gallon water tank instrumented with 737 photomultiplier tubes. The pulse height and arrival times of these photons permit reconstruction of the celestial direction of the original particle, as well as rejection of most of the unwanted cosmic ray showers. Its continuous operation allows observation of both steady and transient sources of TeV gamma rays. Milagro has detected and measured the energy spectrum of gamma rays from the Crab neubla; from active galactic nuclei (AGNS) blazars Mrk 501 and 421 in their active phases; from a gamma ray burster (GRB); and of diffuse TeV gamma ray emission from the inner galactic disc region from interaction of cosmic rays with matter in the galactic disc, and from TeV gamma ray sources in the Cygnus arm of the galaxy. These observations provide new and important data for the understanding of the origin, acceleration and propagation of cosmic rays. Under this NSF grant, work will continue on refining the observations of these and other possible objects, and on analyzing the data.The Milagro experiment and data have provided excellent training ground for undergraduate student research experience and for graduate student training in hardware and software. UCI also has several active programs, such as COSMOS and Quarknet , for outreach to K-12 teachers and students. We have been involved in communicating to school students at K-12 levels and to seniors (Academy of Continued Life Long learning).