Proposal to Construct a Prototype for TAUWER, a Surface Detector Array for 0.1 - 100 EeV t Neutrino Studies

宇宙射线天文学旨在进一步了解天体物理现象，揭示宇宙的结构和演化。能量最高的带电宇宙射线的来源还没有被清楚地确定。分布在整个宇宙中的活动星系核（AGN）和黑洞提供了分布在所有膨胀时代的可能来源。当超高能宇宙射线（uhecr）与宇宙微波背景辐射发生非弹性碰撞时，会产生所谓的宇宙中微子。在宇宙的距离上，当中微子到达地球时，它们的混合产生了大约相等的三种中微子。AGN喷流中质子激波加速的各种天体物理模型给出了0.1-1.0 EeV范围内的中微子通量和能量分布。因为中微子的横截面随着能量的增加而上升，所以在这个能量范围内的中微子能量太大，无法穿透地球。这个小组提议建造一个小型的原型TAUWER阵列，用来探测由在地壳中沿弦向上运动的tau中微子产生的tau轻子的衰变。探测器将安装在陡峭的山坡上，沿着天顶角92度的弦向下观测。这项建议将启动TAUWER项目，建立5个监测站，研究它们在实地的表现，并确定整个系统的改进和简化。对原型检测元件进行了测试，显示出对向上和向下移动的粒子有明显的区分能力。TAUWER是一个成本适中、可快速部署的实验，将提供新的测量能力，并与该领域的其他项目有很好的重叠。这项为期一年的工作的成功完成将确定安装和操作完整的TAUWER的可行性。该提案借鉴了CMU 2007年春季工程课程的经验，该课程涉及10名本科工程师和社会科学专业的学生。计划将整个项目扩展到高中学生和教师。来自完整装置的数据将补充其他中微子天体物理实验。

Cosmic ray astronomy aims to further the understanding of astrophysical phenomena to shed light on the structure and evolution of the Universe. The sources of the highest energy charged cosmic rays have not been clearly identified. Active Galactic Nuclei (AGN) and black holes distributed throughout the cosmos provide possible sources distributed through all epochs of expansion. Ultra High Energy Cosmic Rays (UHECRs) produce so-called cosmogenic neutrinos when they undergo inelastic collisions with the cosmic microwave background radiation. Over cosmic distances, neutrino mixing produces approximately equal populations of the three neutrino species when they get to the earth. Various astrophysical models for proton shock acceleration in the jets of AGN give a range of neutrino flux and energy distributions in the 0.1-1.0 EeV range. Because the neutrino cross section rises with energy, neutrinos in this energy range are too energetic to penetrate the earth. This group proposes to construct a small prototype TAUWER array that will detect the decays of tau-leptons produced by tau-neutrinos moving upward along a chord in the earth's crust. The detector will sit on a steep mountain slope looking down along the chord near a zenith angle of 92 degrees. This proposal will initiate the TAUWER project, building 5 stations to study their performance in the field and to identify improvements and simplifications for the full system. Prototype detection elements have been tested and show clear discrimination capability between upward-coming and downward-moving particles. TAUWER is a modest cost, quickly deployable experiment that will provide new measurement capability and good overlap with other projects in this area. The successful completion of this one-year effort will establish the feasibility of installing and operating a complete TAUWER. This proposal draws on the experience from a spring 2007 engineering course at CMU involving 10 undergraduate engineers and social science students. An expansion to include high school students and teachers is planned for the full project. Data from the full installation will be complementary to other neutrino astrophysics experiments.