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A new air shower array in the Southern Hemisphere looking for the origins of Cosmic rays: the ALPACA experiment
by Marcos Anzorena, Eduardo de la Fuente, Keitaro Fujita, Rocio Garcia, Kaho Goto, Yuki Hayashi, Kinya Hibino, Naoki Hotta, Ginga Imaizumi, Ana Jimenez-Meza, Yusaku Katayose, Chihiro Kato, Sei Kato, Terusyoshi Kawashima, Kazumasa Kawata, Tatsumi Koi, Hiroshi Kojima, Takuto Makishima, Yoshiki Masuda, Sho Matsuhashi, Mizuki Matsumoto, Rosa Mayta, Pedro Miranda, Atsushi Mizuno, Kazuoki Munakata, Yoshiaki Nakamura, Masaki Nishizawa, Yugo Noguchi, Soichi Ogio, Munehiro Ohnishi, Sosuke Okukawa, Akitoshi Oshima, Mirko Raljevich, Hugo Rivera, Toshinaru Saito, Takashi Sako, Takashi Sako, Toshiya Shibasaki, Shoichi Shibata, Atsushi Shiomi, Martin Subieta, Futatsu Sugimoto, Norio Tajima, Wakiko Takano, Masato Takita, Yuichiro Tameda, Koichi Tanaka, Rolando Ticona, Ivan Toledano-Juarez, Harufumi Tsuchiya, Yoshiki Tsunesada, Shigeharu Udo, Rei Usui, Genki Yamagashi, Katsuya Yamazaki, Yoshichika Yokoe
This is not the latest submitted version.
Submission summary
| Authors (as registered SciPost users): | Marcos Anzorena |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202508_00003v1 (pdf) |
| Date submitted: | Aug. 1, 2025, 9:43 a.m. |
| Submitted by: | Marcos Anzorena |
| Submitted to: | SciPost Physics Proceedings |
| Proceedings issue: | 22nd International Symposium on Very High Energy Cosmic Ray Interactions (ISVHECRI 2024) |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Experimental |
Abstract
The Tibet ASγ experiment successfully detected sub-PeV $\gamma$-rays from the Crab nebula using a Surface Array and underground muon detector. Considering this, we are building in Bolivia a new experiment to explore the Southern Hemisphere, looking for the origins of cosmic rays in our Galaxy. The name of this project is Andes Large area PArticle detector for Cosmic ray physics and Astronomy (ALPACA). A prototype array called ALPAQUITA, with 1/4 the total area of the full ALPACA, started observations in September 2022. In this paper we introduce the status of ALPAQUITA and the plans to extend the array. We also report the results of the observation of the moon shadow in cosmic rays.
Current status:
Reports on this Submission
Strengths
The strengths are:
1) Above 100 TeV gamma ray measurements in the southern hemisphere. 2) Detection of moon shadow at high significance that provides calibration of various parameters.
Weaknesses
The paper has the following weaknesses. However, this is fine considering this as a journal proceeding.
- The language writing needs improvement, and the abbreviations, consistency.
- Limited comparison of results with other major experiments.
Report
Requested changes
- muon detector (MD) is already abbreviated in the Introduction. No need to repeat in the following sections.
- Figure 8: Can you add the contour bar to understand the variations?
- Is the angular resolution extracted from the fit? If so, then provide the parameters with error.
- At the end of the Introduction: A typo is found 'planed'.
- In Conclusion, It doesn't appear nice to the paragraph starts with "">100 TeV"
Recommendation
Ask for minor revision