Cosmic-ray Physics with IceCube

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。该项目的主要目标是在主要宇宙射线的能量依赖组成中寻找从星系宇宙射线过渡到来自星系外来源的更高能量粒子群的特征。虽然冰立方中微子天文台的主要任务是通过测量由下面的中微子引起的深层探测器中的事件来寻找天体物理起源的高能中微子，但冰立方的主要信号是由于大气中宇宙射线相互作用引起的向下事件。通过从下面寻找事件，冰立方利用地球作为盾牌来抵御这种向下的背景。“冰立方”的表面组件“冰顶”构成了一个三维空气淋浴阵列，对研究向下的宇宙射线具有重要的潜力。冰立方/冰顶风淋阵的新颖之处在于它对巧合观测事件的广泛接受。IceTop将利用深层探测器的信号与地表信号的比率来测量初级宇宙辐射中不同核群的相对浓度，该辐射的能量范围由于强度低而无法用卫星直接测量。由IceTop单独测量的阵雨的角度依赖性和数据的其他特征对主要成分也很敏感。这提供了对组成的补充敏感性，原则上将消除用于解释数据的模拟中固有的一些模型依赖性。对博士后和学生的持续依赖为这项拟议的研究提供了更广泛的影响，并坚定地将这一努力作为其教育使命的基础。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The main goal of this project is to search for a signature in the energy-dependent composition of the primary cosmic rays of a transition from galactic cosmic rays to a higher energy population of particles from extra-galactic sources. While the primary mission of the IceCube Neutrino Observatory is to search for high-energy neutrinos of astrophysical origin by measuring events in the deep detector induced by neutrinos from below, the dominant signal in IceCube is due to downward events caused by cosmic-ray interactions in the atmosphere. By looking for events from below, IceCube uses the Earth as a shield against this downward background. With its surface component IceTop, IceCube makes a 3-D air shower array with important potential for studying the downward cosmic rays. The novel feature of the IceCube/IceTop air-shower array is its large acceptance for events observed in coincidence. IceTop will use the ratio of the signal in the deep detectors to the signal on the surface to measure the relative concentration of different groups of nuclei in the primary cosmic radiation in an energy range not accessible to direct measurements with satellites because of the low intensity. The angular dependence of showers measured by IceTop alone and other features of the data are also sensitive to primary composition. This gives a complementary sensitivity to composition that in principle will remove some of the model-dependence inherent in the simulations used to interpret the data. Continued reliance on postdocs and students provides a broader impact to this proposed research and firmly grounds this effort in its educational mission.