Particle Astrophysics with VERITAS

这项提议是为了支持加州大学洛杉矶分校(UCLA)的研究人员参与VERITAS伽马射线望远镜项目。VERITAS(高能辐射成像望远镜阵列系统)由四个大气切伦科夫望远镜组成，目前正在亚利桑那州南部的一个山区建造。安装在每个望远镜的焦平面上的是一组快速光探测传感器。VERITAS探测它们在大气中相互作用的产物产生的高能伽马射线。伽马射线在大气中产生粒子簇射，其中大多数粒子的移动速度快于空气中的光速。这些粒子辐射切伦科夫光，切伦科夫光在短时间内传播到地面。在很短的一段时间内(几纳秒)，这种闪光比夜空背景光更亮，使VERITAS能够在晴朗无月的夜晚探测到它们。在过去的十年里，NASA的康普顿伽马射线天文台和在国家科学基金会和能源部的支持下建造的地面切伦科夫望远镜的发现，使非常高能的伽马射线天文学领域发生了革命性的变化。我们已经发现了许多产生非常高能量辐射的新来源，包括活动星系、伽马射线爆发、超新星遗迹和脉冲星。探测到的伽马射线的能量相当于或超过了人造加速器产生的能量。因此，天体物理学的来源通常涉及利用黑洞附近蕴含的巨大能量，或大质量恒星爆炸时产生的能量。然而，尽管有这些令人兴奋的发现，我们仍然有很多不了解的地方--例如，我们不完全了解这些极端暴力的系统是如何工作的，到目前为止，只有几%的头顶天空被灵敏地探测到。VERITAS代表着我们在探测和了解这些非常高能量粒子的来源方面向前迈出了一大步。Veritas阵列将能够发现比之前检测到的微弱十倍的信号源。每个切伦科夫流星雨都将被多个望远镜观看，这一事实极大地提高了望远镜确定入射伽马射线的方向和能量的能力。Veritas的四个望远镜将在2003至2006年间建造。建成后，VERITAS将成为有史以来在这些波长上建造的最灵敏的天文学仪器。加州大学洛杉矶分校的团队在Veritas的建设中发挥了重要作用，参与了读出望远镜传感器的电子设备的开发，以及用于分析望远镜数据和模拟望远镜性能的计算机软件的开发。我们的努力将包括研究生和博士后研究助理。此外，加州大学洛杉矶分校将主要参与Veritas外联计划，该计划目前正在开发中。

This proposal is to support researchers at the University of California, Los Angeles (UCLA) to participate in the VERITAS gamma-ray telescope project. VERITAS (Very Energetic Radiation Imaging Telescope Array System) consists of four atmospheric Cherenkov telescopes presently under construction at a mountain site in southern Arizona. Mounted in the focal plane of each telescope is an array of fast light detecting sensors. VERITAS detects high-energy gamma rays from the products of their interactions in the atmosphere. A gamma-ray creates a shower of particles in the atmosphere, most of which are moving faster than the speed of light in air. These particles radiate Cherenkov light that propagates to the ground in a short flash. For very brief periods of time (few nanoseconds), this flash is brighter than the night sky background light, allowing VERITAS to detect them on clear, moonless nights.The field of very high-energy gamma-ray astronomy has been revolutionized in the last decade by discoveries made by NASA's Compton Gamma Ray Observatory in space and by ground-based Cherenkov telescopes built with support from the National Science Foundation and the Department of Energy. We have discovered many new sources that produce very high-energy radiation, including active galaxies, gamma-ray bursts, supernova remnants, and pulsars. The energies in the detected gamma rays are comparable to or exceed the energies produced in man-made accelerators. Thus the astrophysics sources typically involve harnessing the enormous energies contained near black holes or energies produced in the explosions of massive stars. In spite of these exciting discoveries, however, there is still a great deal that we do not understand - for example, we do not fully understand how these extremely violent systems work, and to date only a few percent of the overhead sky has been surveyed with sensitivity.VERITAS represents a major step forward in our ability to detect and understand the sources of these very high-energy particles. The VERITAS array will be able to discover sources that are ten times fainter than previously detected. The fact that each Cherenkov shower will be viewed by multiple telescopes greatly improves the telescope's ability to determine the direction and energy of the incoming gamma ray. VERITAS' four telescopes will be constructed between 2003 and 2006. When completed, VERITAS will be the most sensitive instrument ever built for astronomy at these wavelengths. The UCLA group is playing a major role in the construction of VERITAS, participating in the development of the electronics to read out the telescope sensors and in the development of computer software to analyze the telescope data and to simulate the telescope performance. Our efforts will involve both graduate students and postdoctoral research associates. In addition, UCLA will have a major involvement in the VERITAS Outreach Program, which is currently under development.