HitSpooling: an improvement for the supernova neutrino detection system in icecube
HitSpooling: an improvement for the supernova neutrino detection system in icecube
复制标题
HitSpooling：icecube超新星中微子探测系统的改进
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
K. Hanson
中科院分区：
文献类型：
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作者：
David Heereman von Zuydtwyck;K. Hanson
IceCube中微子观测站由5160个光电倍增管（PMT）组成，它们监测地理南极一立方公里深的南极冰。IceCube主要是为了探测能量大于O（100 GeV）的中微子。由于冰的温度低于冰点，光电倍增管的暗噪声率特别低，这使得冰立方能够通过探测爆发来寻找银河系超新星中的中微子为此，一个专门的在线超新星DAQ系统记录了探测器中的撞击总数，而没有来自PMT的任何进一步信息，并在探测器速率显著提高的情况下生成超新星偶极触发。本文在IceCube中实现了标准DAQ的一个新功能HitSpooling。HitSpooling系统在标准DAQ系统中实现，并将光电倍增管的完整原始数据流缓冲数小时或数天。通过阅读超新星候选触发器周围的HitSpool数据的时间段，由在线超新星DAQ系统生成，我们克服了后者的局限性，并且在超新星的情况下可以访问探测器的全部信息。此外，HitSpool数据是研究和理解探测器噪声行为以及来自大气μ子的背景过程的有力来源。HitSpooling的思想是在本论文的范围内发展起来的，并且是手头工作的基础。介绍了标准数据采集系统与超新星数据采集系统的接口。首次对IceCube光学组件中的相关暗噪声分量进行了定量分析，并对可能的消除方法进行了讨论。分析了在HitSpool数据中识别触发和亚阈值大气μ介子并从可能的超新星信号中减去它们的可能性。此外，还开发了从HitSpool数据到超新星DAQ类型数据的转换，这允许比较两种数据类型的光变曲线和选定超新星候选触发点的重要性。
The IceCube Neutrino Observatory consists of a lattice of 5160 photomultiplier tubes (PMTs)which monitor one cubic kilometer of deep Antarctic ice at the geographic South Pole.IceCube was primarily designed to detect neutrinos of energies greater than O(100 GeV).Due to subfreezing ice temperatures, the photomultipliers' dark noise rates are particularlylow which enables IceCube to search for neutrinos from galactic supernovae by detectingbursts of MeV neutrinos emitted during the core collapse and for several seconds following.For that purpose, a dedicated online supernova DAQ system records the total number of hitsin the detector, without any further information from the PMTs, and generates supernovacandidate triggers in case of a significant detector rate enhancement. A new feature to thestandard DAQ, called HitSpooling, was implemented in IceCube during this thesis. TheHitSpooling system is implemented in the standard DAQ system and buffers the completeraw data stream of the photomultipliers for several hours or days. By reading out time periodsof HitSpool data around supernova candidate triggers, generated by the online supernovaDAQ system, we overcome the limitations of the latter and have access to the entire informationof the detector in case of a supernova. Furthermore, HitSpool data is a powerfulsource for studying and understanding the noise behavior of the detector as well as backgroundprocesses coming from atmospheric muons. The idea of HitSpooling was developed in thescope of this thesis and is the basis of the work at hand. The developed interface between thestandard DAQ and the supernova DAQ system is presented. The correlated dark noise componentin optical modules of IceCube is quantified for the first time and possible explanationsare discussed. The possibility of identifying triggering and subthreshold atmospheric muonsin HitSpool data and subtracting them from a possible supernova signal is analyzed. Furthermore,the conversion from HitSpool data to supernova DAQ type data was developedwhich allows for a comparison of both data types with respect to lightcurves and significancesof selected supernova candidate triggers.