宇宙微中子之無線電波探測研究

Abstract

極高能宇宙射線及宇宙微中子的研究已行之有年,而近年來關於無線電波波段的探測方法逐漸地被開發、討論。南極天文粒子地磁同步輻射觀測站 (Taiwan Astroparticle Radio Observatory of GeosynchrotronEmission,簡稱 TAROGE­M) 探測無線電波,坐立於南極的墨爾本山上,以 3 支水平及 1 支垂直指向北面的天線來觀測掠過地球的宇宙微中子 (Earth­Skimming Neutrino) 。由於墨爾本山是羅斯冰架附近比較高的山,與附近的地形有足夠的距離,容讓從微中子演變的濤子 (Tau lepton) 有足夠的距離發展大氣簇射,與地磁作用並引發足夠的電磁波。借此,TAROGE­M 才有能力觀測掠過地球的微中子訊號。本論文就 TAROGE­M 的條件進行模擬,探討此系統探測掠過地球的宇宙微中子的可行性,並就 ANITA (ANtarctic Impulse Transient Antenna) 及另一由台大次震宇宙館負責的 ARIANNA­-HCR 進行模擬,從而確定模擬的可信性及廣泛性,並比較各實驗對濤子微中子的靈敏度。此外,南極的熱氣球實驗 (ANITA) 從過去三次飛行中獲得豐碩的成果之後,2016 年進行了第四次的飛行。而 ANITA-­I 及 ANITA-­III 分別各測量到一次異常的訊號。由於目前仍沒有確切的物理背景能解釋這兩個訊號 的來源,世界各地的物理學家都正以不同的理論嘗試了解當中的原因。本論文亦會探討倘若異常訊號的物理過程與濤子微中子一樣的情況下,TAROGE-­M 理應接收到多少此等訊號。

The detection of the ultra high energy cosmic rays (UHECRs) and the cosmic neutrinos has been studied for ages. In the past decades, the use of radio frequency waves (RF) to detect UHE cosmic rays and neutrinos has advanced significantly. The Taiwan Astroparticle Radio Observatory of Geosynchrotron Emission ­ Mt. Melbourne (TAROGE-­M) detects ultra ­wide band impulsive radio frequency (RF) signals emitted by the air­ shower with three horizontal and one vertical antennas pointing to North. It was located on top of Mt. Melbourne in Antarctica. The height of Mt. Melbourne helps the detection of radio signal because the air showers have enough distance to develop and deflect by the geomagnetic field for creating a detectable signal before reaching the detector on the mountain. This thesis I present a comprehensive study of the sensitivity of TAROGE-­M to a diffuse tau neutrino flux detected via tau ­lepton ­induced air showers with the standard model. Besides, I will present the comparison of experiments, including TAROGE-­M, ANtarctic Impulse Transient Antenna (ANITA) and ARIANNA­-HCR, with the same simulation in order to show the flexibility and reliability of this simulation. ANITA collaboration has recently reported the observation of two anomalous up-going air­ shower events with air shower energies of 0.6 EeV, observed during the first and the third flight. Since there is no concrete explanation of these two events, physicists around the world are trying to interpret them with different hypothesis. This thesis would also predict how many same kind of events TAROGE­-M should detect, assuming the mechanism of these events and tau neutrino are the same.