Study of the Highest Energy Cosmic Rays with the Pierre Auger Observatory

对超高能宇宙射线(UHECR)的测量提供了一种前所未有的宇宙视角，并提供了比地面加速器所能获得的能量更高的天文物理信息。南半球最大的宇宙线探测器阵列Pierre Auger天文台(PAO)所进行的观测增进了我们对UHECR源的理解，包括粒子如何在极端环境中加速。该奖项支持科罗拉多矿业学院(Mines)和凯斯西储大学(CWRU)的研究人员通过对PAO仪器的重大贡献继续研究最高能量粒子。获奖活动将利用创新技术研究PAO探测器和大气系统不确定性，使之能够将天空中UHECR源的微妙表现与观测到的初级粒子质量和电荷联系起来。该小组还将继续通过微阵列探测器Auger@TA对PAO和北半球望远镜阵列天文台之间观测到的宇宙线能量尺度和通量差异进行调查。该计划包括为研究生和本科生提供实验方法方面的研究培训，包括在大气科学和商业GPS授时方面潜在的更广泛应用。目前PAO测量的能谱、各向异性、主成分、中微子和光子极限以及质子-空气截面提供了进入高能宇宙的独特途径。大气对PAO荧光探测器绝对和相对能量尺度的影响仍然是天文台科学的关键要素，由该小组管理的测试束激光设施是现有阵列和正在进行的升级AugerPrime的核心。同时，Auger@TA微阵列目前正在调试中，计划进行为期两年的科学运行，将提供同步和独立的广泛空气簇射事件数据，以交叉校准PAO和TA探测器。这样做将允许对实验的宇宙线能量尺度进行第一次直接比较，以确定观察到的能量尺度和通量差异的来源。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Measurements of ultra-high-energy cosmic rays (UHECRs) have provided an unprecedented view of the universe and access to astro-physics at energies beyond those accessible at terrestrial accelerators. Observations performed with the Pierre Auger Observatory (PAO), the largest cosmic ray detector array in the southern hemisphere, have advanced our understanding of UHECR sources, including how the particles are accelerated in the extreme environments. This award supports researchers at the Colorado School of Mines (Mines) and Case Western Reserve University (CWRU) to continue studies of the highest energy particles via major contributions to PAO instruments. The awarded activities will leverage innovative techniques to study the PAO detector and atmospheric systematic uncertainties, making it possible to couple the subtle manifestations of UHECR sources in the sky with the observed primary particle mass and charge. The team will also continue the investigations of cosmic ray energy-scale and flux discrepancies observed between PAO and the Telescope Array Observatory in the northern hemisphere via the micro-array detecter Auger@TA. The program includes research training in experimental methods for graduate and undergraduate students, including potential broader applications for atmospheric science and commercial GPS timing.The current PAO measurements of energy spectra, anisotropy, primary composition, neutrino and photon limits, and proton-air cross-section provide unique access to the high-energy universe. The influence of the atmosphere on the PAO fluorescence detector absolute and relative energy-scales remains a crucial element of science of the observatory, and the test-beam laser facilities managed by the team are central to the existing array and the on-going upgrade, AugerPrime. In parallel, the Auger@TA micro-array is currently under commissioning, with a planned two-year science run that will provide simultaneous and independent extensive air shower event data to cross-calibrate PAO and TA detectors. Doing so will permit a first direct comparison of the cosmic-ray energy-scales of the experiments to determine the origin of the observed energy-scale and flux discrepancies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.