以TAROGE-3天線陣列尋找極高能宇宙射線

Abstract

台灣天文粒子地磁同步輻射電波觀測站（TAROGE）是台灣首個旨在探測由超高能宇宙射線（UHECR）的大氣簇射所引起的脈衝同步輻射電波信號。TAROGE 天線陣列設置於面向太平洋的高山上，使其能進行近地平線觀測。本研究聚焦於 TAROGE-3 站點，旨在展示其 UHECR 探測能力。通過分析 TAROGE-3數據，我們已成功探測到 UHECR 候選事件。 TAROGE-3陣列包括 12個雙堆疊的對數週期偶極天線（LPDA），工作頻段為180-333 MHz。TAROGE-3 的關鍵組件之一是其觸發系統，該系統利用多頻帶共振技術來抑制熱噪聲和周圍連續波（CW）噪聲。觸發系統採用了現場可編程閘陣列（FPGA），處理信息，決定何時為數據獲取（DAQ）系統發起觸發信號。 為了降低人為背景噪聲，已實施軟件過濾技術來識別 UHECR 候選者。此外，還採用了模板匹配技術來確認 UHECR 候選者。TAROGE-3 自 2018 年 7 月運行至今，五年間的工作週期達到了 0.6。在首年數據收集期間，TAROGE-3 每週大約探測到 0.2 個 UHECR 候選事件。從 2018 年開始的五年運行期間，基於首年數據分析，該站點已探測到 5 個 UHECR 候選事件。此外，通過對 TAROGE-3 數據的持續分析，仍有更多 UHECR 候選事件有待揭示。

The Taiwan Astro-particle Radiowave Observatory for Geo-synchrotron Emissions(TAROGE) is the first experimental project in Taiwan aimed at detecting impulsive Geosynchrotron radio signals induced from extensive air shower by ultra-high energy cosmicrays (UHECR). The TAROGE antenna arrays are placed on high mountains facing thePacific Ocean which enables near-horizon observations. This study focuses on TAROGE3 Station and aims to display its UHECR detection capabilities. We have successfully detected UHECR candidates through the analysis of TAROGE-3 data. The TAROGE-3 array comprises 12 dual-stacked Logarithmic Periodic Dipole Antennas(LPDA) operating within the passband of 180-333 MHz. One of the critical components of TAROGE-3 is its trigger system, which utilizes a multi-frequency band coincidence technique to suppress thermal noise and ambient continuous wave (CW) noise. The trigger system, implemented with a field programmable gate array (FPGA), that processes coincidence information, determines when to initiate a trigger signal for the data acquisition (DAQ) system. To reduce anthropogenic backgrounds, software filtering techniques have been implemented to identify UHECR candidates. Additionally, a template matching has been employed to provide final confirmation of UHECR candidates. TAROGE-3 has been in operation since July 2018. It achieves a duty cycle of 0.6 over the five-year time span. TAROGE-3 detected approximately 0.2 UHECR candidate per week during the first year of data collection. Over the course of its five-year operation since 2018, the station has detected 5 UHECR candidates based on the analysis of the initial year''s data. Furthermore, there remain additional UHECR candidates to be unveiled through continued analysis of TAROGE-3 data.