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初级宇宙射线的能量依赖成分中寻找从银河宇宙射线向来自银河系外来源的高能粒子群过渡的特征。虽然冰立方中微子观测站的主要使命是通过测量来自下方的中微子在深探测器中引起的事件来寻找天体物理学起源的高能中微子，但冰立方中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。通过寻找来自下方的事件，IceCube使用地球作为对抗这种向下背景的盾牌。IceCube的表面组件IceTop构成了一个三维空气簇射阵列，具有研究向下宇宙射线的重要潜力。IceCube/IceTop空气簇射阵列的新特点是它对符合观测的事件的接受度很高。IceTop将利用深层探测器中的信号与表面上的信号之比来测量初级宇宙辐射中不同核群的相对浓度，初级宇宙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也对主要成分敏感。这提供了一种对成分的补充敏感性，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，并在其教育使命中坚定地支持这项努力。

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.