학술논문
TAROGE-M: Radio Antenna Array on Antarctic High Mountain for Detecting Near-Horizontal Ultra-High Energy Air Showers
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Collaboration, TAROGE; Wang, Shih-Hao; Nam, Jiwoo; Chen, Pisin; Chen, Yaocheng; Choi, Taejin; Ham, Young-bae; Hsu, Shih-Ying; Huang, Jian-Jung; Huang, Ming-Huey A; Jee, Geonhwa; Jung, Jongil; Kim, Jieun; Kuo, Chung-Yun; Kwon, Hyuck-Jin; Lee, Changsup; Leung, Chung-Hei; Liu, Tsung-Che; Shiao, Yu-Shao J; Shin, Bok-Kyun; Wang, Min-Zu; Wang, Yu-Hsin; Collaboration, ARIANNA; Anker, Astrid; Barwick, Steven W; Besson, Dave Z; Bouma, Sjoerd; Cataldo, Maddalena; Gaswint, Geoffrey; Glaser, Christian; Hallmann, Steffen; Hanson, Jordan C; Henrichs, Jakob; Kleinfelder, Stuart A; Lahmann, Robert; Meyers, Zachary S; Nelles, Anna; Novikov, Alexander; Paul, Manuel P; Pyras, Lilly; Persichilli, Christopher; Plaisier, Ilse; Rice-Smith, Ryan; Seikh, Mohammad FH; Tatar, Joulien; Welling, Christoph; Zhao, Leshan
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Abstract
TAROGE-M is a self-triggered radio antenna array atop the 2700 m high Mt.Melbourne in Antarctica, designed to detect impulsive geomagnetic emission fromextensive air showers induced by ultra-high energy (UHE) particles beyond 0.1EeV, including cosmic rays (CRs), Earth-skimming tau neutrinos, andparticularly, the "ANITA anomalous events" (AAEs) from near and below thehorizon, which origin remains uncertain and requires more experimental inputsfor clarification. The detection concept of TAROGE-M takes advantage of a high altitude withsynoptic view toward the horizon as an efficient signal collector, and theradio quietness as well as strong and near vertical geomagnetic field inAntarctica. This approach has a low energy threshold, high duty cycle, and iseasy to extend for quickly enlarging statistics. Here we report experimentalresults from the first TAROGE-M station deployed in 2020, corresponding to$25.3$-days of livetime. The station consists of six receiving antennasoperating at 180-450 MHz, and can reconstruct source directions with$\sim0.3^\circ$ angular resolution. To demonstrate its ability to detect UHEair showers, a search for CR signals in the data was conducted, resulting inseven identified events. These events have a mean reconstructed energy of$0.95_{-0.31}^{+0.46}$ EeV and zenith angles between $25^\circ-82^\circ$, withboth distributions agreeing with simulations. The estimated CR flux is alsoconsistent with results of other experiments. The TAROGE-M sensitivity to AAEsis approximated by the tau neutrino exposure with simulations, suggestingcomparable sensitivity as ANITA's at $~1$ EeV energy with a few station-yearsof operation. These first results verified the station design and performancein a polar and high-altitude environment, and are promising for furtherdiscovery of tau neutrinos and AAEs after an extension in the near future.