Analysis of IceCube Data

从2006年5月开始的三年冰立方数据分析[j]。由P. B. Price领导的伯克利小组自1991年AMANDA高能中微子天体物理学项目成立以来一直参与其中。除了参与建设不断发展的冰立方天文台之外，这笔新的拨款将为目前由12名研究人员组成的小组提供一些支持，帮助他们分析从冰立方流出的数据。以下是他们将研究的几个主题：-电子中微子引起的电磁级联分析算法的发展。它们将用于研究大气和天体物理起源的高能级联。利用他们新的重建算法，他们将寻找来自强大的河外高能中微子源的巨大耀斑产生的中微子。他们将利用他们的方法，通过“叠加”来自特定高能中微子点源家族的数据，期望看到来自某些活跃星系的中微子，从而增加信号对噪声的影响。通过一种特殊的“慢粒子触发器”，他们将寻找假设的粒子，如奇异夸克、超大质量磁单极子和q球，这些粒子将通过地球的大部分地区而没有明显的减速，并且可以通过它们的慢速度（小于光速的1%）来识别。理论学家最近计算出，星系外超新星核心坍缩产生的能量高达1万亿电子伏特的中微子可能在冰立方中被探测到，它们的来源距离地球大约5000万光年。如果能在几秒钟内从天空的同一方向探测到至少两个这样的中微子，那将是一个准确无误的信号。这一发现对天体物理学、引力物理学和相对论都具有重大意义。伯克利小组在为阿曼达和冰立方发明新设备方面处于领先地位，并将它们应用于科学前沿的完全不同的主题。第一个这样的设备是他们的激光尘埃记录仪，他们用它来探测火山灰层和与气候相关的尘埃浓度，通过这种方法，他们发现了大型火山爆发和气候突变之间的因果关系。通过在灰尘记录仪上添加荧光通道，他们创造了一个生物记录仪，用它他们可以检测含有叶绿素和色氨酸（所有细胞中的一种氨基酸）等分子的各种微生物，生物记录仪诱导的荧光使他们能够研究微生物沉积的历史及其与气候和火山作用的可能相关性。最近的一个例子表明了他们的兴趣之广，那就是他们认识到，对冰立方弦底部附近光电管噪音神秘增加的解释是，在极深的地方，温度足够温暖，可以使流动的冰发生剪切，在此过程中产生可见光和声音。在某些固体（如冰）的突然变形过程中，这种鲜为人知的摩擦发光光学现象将使用冰立方的数据进行研究。毫无疑问，当他们分析冰立方的数据时，会有新的衍生品。

nalysis of IceCube Data During the Three Year Period Beginning May 2006P. B. Price, Physics Dept., U. C. Berkeley The Berkeley group led by P. B. Price has participated in the AMANDA high-energy neutrino astrophysics project since its inception in 1991. Beyond their participation in the construction of the growing IceCube observatory, this new grant will provide some support to the present group of 12 researchers as they analyze data flowing from IceCube. Here are a few of the topics they will study: - Development of algorithms for analysis of electromagnetic cascades induced by electron neutrinos. They will be used to study high-energy cascades of both atmospheric and astrophysical origin. - Using their new reconstruction algorithms, they will look for neutrinos produced by giant flares from powerful extragalactic sources of high energy neutrinos. - They will exploit their method for increasing signal to noise by "stacking" data from particular families of point sources of high energy neutrinos with the expectation of seeing neutrinos from certain classes of active galaxies. - By means of a special "slow-particle trigger", they will search for hypothetical particles such as strangelets, supermassive magnetic monopoles, and Q-balls that will pass through much of the earth without significant slowing and that can be recognized by their slow speed (less than 1% the speed of light). - Theorists have recently calculated that neutrinos with energy up to a trillion electron volts generated in core-collapse extragalactic supernovae may be detectable in IceCube for sources at distances within about 50 million light years of Earth. An unmistakable signal would be the detection of at least two such neutrinos from the same direction in the sky within a few seconds. Such a discovery would have great significance for astrophysics, gravitational physics, and relativity.The Berkeley group has led in inventing new devices for AMANDA and IceCube and in applying them to totally different topics at the forefront of science. The first such device was their laser-powered dust logger, which they have used to detect volcanic ash layers and climate-correlated dust concentrations, by means of which they discovered a causal relationship between large volcanic eruptions and abrupt climate change. By adding fluorescence channels to the dust logger, they created a biologger, with which they can detect various classes of microbes that contain molecules such as chlorophyll and tryptophan (an amino acid in all cells) whose fluorescence induced by the biologger allows them to study the history of microbial deposition and its possible correlation with climate and volcanism. A very recent example of the breadth of their interest is their realization that the explanation of the mysterious increase in phototube noise near the bottom of the IceCube strings is the light emitted by the glacial ice at great depths where the temperature is warm enough to allow shear of the flowing ice to develop, during which visible light and sound are produced. This poorly understood optical phenomenon of triboluminescence induced during jerky deformation of certain solids such as ice will be studied using IceCube data. There will no doubt be new spinoffs as they analyze ongoing IceCube data.