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Workshop for the Global Cosmic Ray Observatory -- Challenging Next-Generation Multi-Messenger Astronomy with Interdisciplinary Research
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Asia/Tokyo
Koshiba Hall, Hongo Campus (University of Tokyo )
Koshiba Hall, Hongo Campus
University of Tokyo
7-3 Hongo Bunkyo-ku Tokyo 113-0033 Jpan
Description
Ultra-high-energy cosmic rays (UHECRs), the most energetic particles in the universe, are a new messenger that will play a crucial role in the future of multi-messenger astronomy. Due to their extremely high energies, UHECRs are less deflected by the Galactic and extragalactic magnetic fields, offering the potential to trace their arrival directions back to their origin.
This is the 4th workshop for the Global Cosmic Ray Observatory (GCOS) to foster further networkings with researchers and students. We will discuss the latest results and physical interpretations of UHECRs, as well as the current status and future perspectives of GCOS. A major focus will be on exploring the prospects for multi-messenger astronomy after source identification, from both theoretical and experimental perspectives.
In order to enhance links between researchers and students who will lead future projects, the agenda includes ample time for in-depth discussions. There will also be opportunities to exchange ideas on education and outreach activities using cosmic rays.
The workshop will be broadcastd via Zoom.
Invited speakers
- Hiromasa Suzuki, Miyazaki Univ.
- Koji Noda, Chiba Univ.
- Alessio Percelli, Universidad de Antofagasta
- Luna Pellegri, University of the Witwatersrand and iThemba LABS
- Shunsuke Sakurai, Osaka Metropolitan Univ.
- Hitoshi Oshima, ICRR
- Shigeo Kimura, Tohoku Univ.
- Michael Unger, Karlsruhe Institute of Technology
- Kohta Murase, Penn State Univ.
- Ioana Maris, Université Libre de Bruxelles
- Tomohiro Inada, Kyusyu Univ.
- Ralph Engel, Karlsruhe Institute of Technology
- Jörg Hörandel, Radboud University
Local organizers
Toshihro Fujii, Yuko Ikkatai, Eiji Kido, Hiroaki Menjo, Yutaka Ohira, Takashi Sako, Yuichiro Tameda
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Cosponsers/共催
- 東京大学 次世代ニュートリノ科学・マルチメッセンジャー天文学連携研究機構
- 研究拠点形成事業「極高エネルギー宇宙線で極限宇宙を探る国際研究拠点ネットワーク」代表：荻尾彰一
- 学術変革領域研究(A) 計画研究「環境を視る：宇宙線ミューオンを用いた宇宙・地球環境の可視化」代表：多米田裕一郎
- 基盤研究(A)「新型大気蛍光望遠鏡アレイによる極高エネルギー宇宙線天文学の開拓」代表：藤井俊博
- 二国間交流事業 共同研究「10ペタ電子ボルトの宇宙線源探査へ向けた2層式水チェレンコフ検出器の開発」代表：藤井俊博
- 基盤研究(C)「AIが拓くシチズンサイエンス：専門家と市民の役割再定義と社会的効果の検証」代表：一方井祐子
(Header image credit: Souichi Takahashi)
Contact
Participants
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Registration
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Opening and lesson learned from current multi-messenger astronomy (Convener: Toshihiro Fujii)
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1
The Global Cosmic Ray Observatory (GCOS) – Status and Perspectives
In this introductory talk, we will provide an overview of the past and present activities of the Global Cosmic Ray Observatory (GCOS) and offer a look ahead to the future. Where do we currently stand, and where do we want to go in the coming years? What challenges lie ahead, and what could be the next steps on our path forward?
Speaker: Jörg Hörandel -
2
Declination Dependence in the Cosmic Ray Energy Spectrum
The Telescope Array (TA), the largest ultra-high-energy cosmic ray (UHECR) observatory in the Northern Hemisphere, continues to deliver precise measurements of the cosmic ray energy spectrum, thanks to its stable performance and high data acquisition efficiency. These observations have revealed three prominent spectral features, commonly referred to as the ankle, shoulder, and cutoff, which are key to probing the origin and propagation mechanisms of UHECRs. In this presentation, we will share the most recent energy spectrum results obtained from the TA surface detector array and explore the spectral differences observed between the Northern and Southern skies.
Speaker: Jihyun Kim (Osaka Metropolitan University) -
3
SWGO: future perspective in the multi-messenger era
To understand the Universe at the High-Energy scale of astronomy, observation must rely on all messengers: Gamma rays, Cosmic Rays, Neutrinos, and the recent Gravitational Waves. This multi-messenger approach requires the effort of many experiments worldwide, each optimized for one of the messengers. The Southern Wide-field Gamma-ray Observatory, SWGO, is a gamma-ray one.
Built following the experience of HAWC, SWGO is planned to consist of over 3,500 Water Cherenkov Detectors (WCDs) in its final configuration. Its target sensitivity spans from approximately 100 GeV up to the PeV. As an array of WCDs, SWGO is also capable of detecting cosmic rays in the TeV–PeV energy regime.
In this talk, the recent plans and studies of SWGO will be highlighted, as well as plans for the multi-messenger program with cosmic rays, including the SWGO energy range and gateways toward the GCOS regime.
Speaker: Alessio Porcelli (Universidad de Antofagasta) -
4
A new air shower array in the Southern Hemisphere looking for the origins of Cosmic rays: the ALPACA experiment
In 2019 the Tibet ASγ collaboration reported the detection of sub-PeV γ-
rays coming from the Crab nebula using a novel technique with a Surface Array and underground water Cherenkov muon detector to discriminate against hadrons. With the same idea, we are now building a new experiment to explore the gamma-ray sky in the Southern
Hemisphere looking for the origins of cosmic rays in our Galaxy. The
name of this new project is the Andes Large area PArticle detector for Cosmic ray physics and Astronomy (ALPACA).Installed at 4740 m in the Chacaltaya plateau, ALPACA will cover an area of 83 000 m2 with 401 scintillation counters and 4 underground muon detectors of 900 m2. A prototype array called ALPAQUITA, with 1/4 of the total area of the full ALPACA, started observations in September 2022.
In this presentation we show the current status of ALPAQUITA and the plans to extend the array to reach the full operation of the experiment. We will also report the results of the analysis of the initial data, including the observation of the moon shadow in cosmic rays.
Speaker: Dr Marcos Anzorena (ICRR, The University of Tokyo) -
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Multi-messenger astronomy with IceCube
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Speaker: Dr Koji Noda (Chiba University)
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1
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UHECR Review and interdisciplinary session (Convener: Eiji Kido)
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Open Questions at Ultra-High Energies and the Path Forward with GCOS
We give a brief review of our current knowledge of the spectrum, composition, and anisotropy of cosmic rays at ultra-high energies and outline the key open questions. We then discuss the prospects for resolving the puzzle of UHECR origin with the Global Cosmic Ray Observatory (GCOS), along with its capabilities to advance our understanding of fundamental physics through studies of cosmic magnetism and particle physics beyond collider energies.
Speaker: Michael Unger (Karlsruhe Institute for Technology) -
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Unravelling Photoabsorption in Light Nuclei: Insights from the PANDORA Project
The electric-dipole (E1) strength plays a central role in understanding photoabsorption reactions, offering insights into nuclear structure, collective excitations, and the nuclear response to external fields. While E1 strength has been extensively investigated in heavy nuclei (A > 90)—where shell effects and nucleon correlations are less pronounced—the situation is more complex for lighter nuclei (A < 60). In these systems, clustering phenomena, isospin mixing, nuclear deformation, and neutron–proton pairing strongly influence charged-particle branching ratios. As a result, the common assumption that the neutron-emission channel (g,xn) adequately represents the total photoabsorption cross section breaks down. This complexity not only challenges theoretical interpretation but also leads to divergent model predictions. The issue has direct consequences for astrophysics, particularly the study of ultra-high-energy cosmic rays (UHECRs). Since their origin and production sites remain unresolved, improving our knowledge of UHECR energy-loss processes during extragalactic propagation is important.
The PANDORA project (Photo-Absorption of Nuclei and Decay Observation for Reactions in Astrophysics) is an international effort dedicated to systematically measuring photoabsorption cross sections, as well as proton, alpha, and gamma branching ratios, for light stable nuclei (A < 60). These results will provide essential constraints for nuclear models, which in turn will be implemented in UHECR propagation simulations. In this presentation, I will introduce the goals of the PANDORA project and discuss preliminary findings from its first experiment.
Speaker: Luna Pellegri -
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What do X-ray observations tell us about cosmic-ray acceleration physics in extreme environments in our Galaxy?
X-ray emission from extreme cosmic-ray accelerators in our Galaxy, such as supernova remnants, black hole binaries, and the Galactic center, provides fruitful information of the acceleration environments. In X-rays, we see thermal emission including electron thermal bremsstrahlung continuum and emission lines from the plasma in the acceleration sites, as well as electron synchrotron and non-thermal bremsstrahlung emission. Thermal X-rays give constraints on the kinetic energy, three-dimensional motion, dynamical timescale, and ambient density. I will review how X-ray observations are useful in understanding acceleration environments in our Galaxy. In particular, I will present the latest results and future prospects with the X-ray Imaging and Spectroscopy Mission (XRISM), which provides first non-dispersive high-resolution X-ray spectra, and large field-of-view imaging spectroscopy data.
Speaker: Hiromasa Suzuki (University of Miyazaki) -
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Photo nuclear reaction and charged particle decay measurement in the PANDORA project.
The PANDORA project aims to elucidate the energy and mass loss processes during intergalactic propagation of Ultra-High Energy Cosmic Rays (UHECRs) from both theoretical and experimental perspectives.
During intergalactic propagation, UHECR nuclei interact with Cosmic Microwave Background (CMB) photons and excite the Giant Dipole Resonance (GDR). The data of particle decay from GDR is essential for understanding the energy and mass loss processes of UHECRs.
Therefore, our project investigates particle decay from GDR excitation in the mass region below A≈60.
The proton beam experiment was conducted at RCNP (The University of Osaka) using the Grand Raiden spectrometer. We measured the branching ratio of charged particle decay using the Si detectors array (SAKRA). In this presentation, I will report on the experimental set-up and the preliminary result of data analysis.Speaker: Yohei Sasagawa (PCNP, Osaka university) -
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Mini-EUSO results and possible synergies with GCOS science and interdisciplinary research
Mini-EUSO is a telescope launched on board the International Space Station in 2019 and currently located in the Russian section of the station and viewing our planet from a nadir-facing UV-transparent window in the Zvezda module. The instrument is based on an optical system employing two Fresnel lenses and a focal surface composed of 36 Multi-Anode Photomultiplier tubes, 64 channels each, for a total of 2304 channels with single photon counting sensitivity and an overall field of view of 44 degrees. Mini-EUSO has multidisciplinary scientific objectives, among them the search for nuclearites and Strange Quark Matter, the study of atmospheric phenomena such as Transient Luminous Events, meteors and meteoroids, the observation of sea bioluminescence. Mini-EUSO can map the night-time Earth in the near UV range (predominantly between 290 – 430 nm), with a spatial resolution of about 5.9 km and different temporal resolutions of 2.5 us, 320 us and 41 ms. Mini-EUSO observations are extremely important to better assess the potential of a space-based detector of Ultra-High Energy Cosmic Rays (UHECRs) such as POEMMA and M-EUSO. In this contribution we describe the detector and present the various phenomena observed in more than five years of operation and place them in the context of GCOS developments, as well as its science and interdisciplinary research.
Speaker: Mario Edoardo Bertaina
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Poster session, Discussion, information exchange and collaborative work 1
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11
2024年5月におけるフォーブッシュ効果の観測
本研究では、太陽フレア発生時に宇宙線到来数が減少する現象であるフォーブッシュ効果を、太陽活動が活発であった2024年5月に観測した。具体的には、学校に設置したQuarknet検出器4つを使用し、2つずつ重ねた状態でコインシデンスレベルを2に設定して宇宙線を検出した。また、e-labから世界各地のQuarknet検出器のデータを収集し、これらと私達が測定したデータを用いて、大規模な太陽フレアが頻発した2024年の5月9日から15日の宇宙線到来数をPythonによって観測地点ごとに求め、比較した。その結果、4％程度の減少が複数回見られた。
本研究の結果から、Quarknet検出器のような比較的小型で安価な検出器でもフォーブッシュ効果の観測ができることも併せてわかった。Speakers: 瑞紗 松永, 舞羽 牛田, 菜々香 福﨑, 采佳 倉科 -
12
Analysis of Inclined Air Shower Events Observed by the TAx4 SD
The Telescope Array (TA) experiment has been observing extensive air showers (EAS) induced by ultrahigh energy cosmic rays (UHECR) since 2008. The TA$\times$4 upgrade aims to expand the detection area of TA at the highest energies to four times its original size with 500 additional surface detectors (SD) with the nearest neighbor spacing extended from 1.2km to 2.08km. Half of the new detectors were installed in 2019, and have been operating since then. The objective of the upgrade is to significantly increase the number of events for analysis. In addition to the physical expansion, TA is also investigating improvements to its reconstruction procedure. In particular TA has previously accepted events only up to a maximum zenith angle of 55 degrees. In this paper we describe the results of extending the acceptance to 65 degrees in zenith, which required the energy estimation table to be expanded to include simulated events up to 70 degrees in zenith. To validate the accuracy of the simulation, which is crucial for both the energy estimation and for the calculation of detector acceptance, we compared distributions of key parameters between observed and simulated TA$\times$4 data. We confirmed that there was no significant discrepancy between the two, in particular for the extended range of zenirth angles. We also show the measured TA$\times$4 SD energy spectrum, including large zenith angle events based on three years of observation.
Speaker: Chisato Koyama (ICRR, The University of Tokyo) -
13
Autonomous Observation Tests and Detector‐Upgrade Progress of the CRAFFT Telescope for UHECR Detection
The origin of ultra-high-energy cosmic rays (UHECRs) remains unsolved. Statistically identifying their sources requires long-term, all-sky observations that collect a sufficiently large event sample. To meet this challenge, we are developing CRAFFT—a low-cost atmospheric-fluorescence telescope that employs a Fresnel lens.
The current CRAFFT prototype has already recorded UHECR events with its optimised detector module. We are now pursuing a two-stage upgrade: (i) construction of a control system that enables fully autonomous observations and (ii) further optimisation of the optical system.
In this presentation, we present an overview of the fully autonomous observation campaign scheduled for this summer, building on the results of environmental-monitoring tests conducted over the past year. We also report on progress in detector upgrades aimed at lowering the cost per field of view by employing smaller photomultiplier tubes (PMTs).
Speaker: Kota Tokuyama (Shinshu University) -
14
Constrain the limits of UHECR source parameters with 100EeV multiplets
Current observations with the Pierre Auger Observatory and Telescope Array experiment do not show clear small-scale anisotropy (multiplets). The absence of an anisotropy can set the parameters of UHECR source: source density, mass composition, and magnetic field strength.
In this study, we set the lower limit of the parameters with a large-scale structure simulated catalog and cosmic-ray propagation. In addition to "light" (proton) and "heavy" (iron) composition, we consider "super-heavy" (uranium) composition, which is suggested from the "Amaterasu" event (Farrar 2024, Zhang et al. 2024).
In any parameter set, single-proton composition is rejected. We also set the lower limits of source density and magnetic field strength for the single-iron and uranium cases.
In this talk, we discuss the current status of our work and future prospects for full-sky and highest energy events search with the Global Cosmic Ray Observatory (GCOS).Speaker: Ryo Higuchi -
15
Development of a portable cosmic-ray detector to make particle physics accessible to visually impaired individuals
In recent years, outreach in particle physics has expanded through the proliferation of compact cosmic-ray detectors and citizen-science initiatives. Nevertheless, programs tailored for individuals with visual impairments remain scarce, largely because conventional activities require interpreting measured data through visual graphs. To address this gap, we developed a handheld cosmic-ray detector that sonifies events by mapping the measured signal amplitude (a proxy for deposited energy) to pitch. We piloted inquiry-based workshops using this instrument in physics classes at the Special Needs Education School for the Visually Impaired, University of Tsukuba, and at the “Jump To Science” for blind and low-vision students. This presentation describes the detector’s design and reports insights from these pilot implementations.
Speaker: Mihiro Nukiwa -
16
EarthCARE Laser Event observed by the Fluorescence Detector in the Telescope Array project
The Telescope Array (TA) experiment aims to elucidate the origin of ultra high energy cosmic rays. In this experiment, extensive air showers induced by ultra high energy cosmic rays are observed using Fluorescence Detector (FD) and Surface Detector (SD). The FD measures fluorescence light emitted by air showers and subsequently propagating through the atmosphere.
In the TA experiment, accurate energy determination in air shower analysis is crucial, and one of the main sources of systematic uncertainty is atmospheric transparency.
In this study, the analysis of laser events from EarthCARE (Earth Cloud Aerosol and Radiation Explorer), an Earth observation satellite, is initiated as a new method for estimating atmospheric transparency.
EarthCARE observes the atmosphere by emitting laser pulses and provides various data on clouds, aerosols, and radiative energy.
By analyzing EarthCARE laser events observed by the FD, I aim to reduce the systematic uncertainty in energy determination.Speaker: Masaki TERAMOTO (Osaka Electro-Communication University) -
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Evaluating the performance of a FAST only reconstruction
The Fluorescence detector Array of Single-pixel Telescopes (FAST) is a next-generation cosmic ray experiment aiming to deploy an array of low-cost, autonomous fluorescence telescopes for observing UHECRs. FAST reconstructs the properties of air showers using a top-down approach, where simulated photomultiplier traces are directly compared to data. This process is called the "top-down reconstruction" and requires an accurate first guess of the shower parameters for successful minimisation. In this contribution, we show the performance of the full FAST reconstruction process using a neural network to provide a first guess to the top-down reconstruction. The method is evaluated using the current and near future FAST prototype installations in simulations before being applied to FAST events observed in coincidence with the Telescope Array experiment.
Speaker: Fraser Bradfield -
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Evaluation of long-term PMT gain fluctuations using standard light source analysis with a new air fluorescence telescope
The Fluorescence detector Array of Single-pixel Telescopes (FAST) aims to increase the effective area for ultra-high-energy cosmic rays by deploying a large number of atmospheric fluorescence telescopes over a wide area for the next-generation experimental project like GCOS. The operation is expected to last for more than 10 years, and it is important to understand the aging of the equipment and perform accurate calibration.
We report on the results of evaluating the long-term variation in the gain of photomultiplier tubes of FAST prototypes operating between 2017 and 2025 using a standard light source, accounting for the temperature dependence.Speaker: Haruka Tachibana (Osaka Metropolitan University) -
19
Experimental Investigation of Muon Attenuation in Concrete with Varying Densities
Muon tomography is a technique to visualize the internal structure of objects by utilizing muons, a type of secondary cosmic ray that constantly showers the Earth's surface. In recent years, the demand for muon tomography as an accurate method of non-destructive testing has been increasing, given the current situation marked by a growing number of road collapses and water pipe leakages in developed countries. Nevertheless, the use and experimental application of muon tomography as an imaging technique remains limited to large-scale structures such as pyramids, ancient burial mounds, and volcanoes. Experiments aiming to visualize relatively small-scale structures, such as deteriorated water pipes or underground cavities, remain scarce. In this study, concrete blocks with densities of 2.12 g/cm³, 2.18 g/cm³, and 2.38 g/cm³ were prepared, and their respective muon arrival rates were compared. The uncertainty was estimated by dividing the square root of the count number by the measurement time. Results showed that approximately 12% difference in concrete density led to muon detection rates that remained within the experimental error margin. This presentation will detail the experimental methodology and discuss the potential applications of muon tomography for small-scale infrastructure assessment.
Speaker: Miku Yamamoto -
20
FAST - a stand-alone new generation fluorescence telescope
Fluorescence detector Array of Single-pixel Telescopes (FAST) is an R&D project focused on developing a low-cost fluorescence detector telescope. The FAST project currently operates three telescopes within the Telescope Array experiment, Utah, USA and two telescopes within the Pierre Auger Observatory, Argentina. The FAST telescopes are installed in a hut on a predefined location. The infrastructure is provided by the hosting experiment. The new generation of FAST telescope has slightly modified optics (4 instead 9 mirror segments) and a new enclosure. The telescope is integrated inside a modified container, allowing transport inside the standard shipment container, including all necessary parts of the telescope (optics, camera, filters, electronics, DAQ and power inside the modified container. After installation, the telescope is fully stand-alone with its own solar power system and wireless communication between the other telescopes. The new generation of FAST telescopes represents a potential significant advancement in ultra-high-energy cosmic ray detections. These telescopes are designed for versatility, ease of installation, transport, maintenance and remote operation. Each system features a 1 m^2 aperture, currently using four photomultipliers (PMTs) to facilitate stereo and multi-telescope observations. A key advantage of this design is its inherent flexibility. The optical and camera systems can be readily modified to incorporate additional photodetectors, thereby increasing angular resolution if required.
Speaker: Dr Dusan Mandat (Institute of Physics of the Czech Academy of Sciences) -
21
Improvements of the Reconstruction Program for the TALE Infill SD
TALE infill experiment is further low-energy extension of Telescope Array Low-energy Extension (TALE), aiming to observe cosmic rays with energies from 1 PeV to 100 PeV, with the goal of revealing "knee" and "second knee" in the energy spectrum. 50 surface detectors (SDs) are deployed with 100 m spacing to observe this energy region.
The experiment began operation in November 2023 and has been conducting stable observations since then. In this poster, we report on improvements of the reconstruction program and outline our future analysis plans.Speaker: Haruto Matsushita (Osaka Metropolitan University) -
22
Improving reconstruction accuracy by incorporating air shower asymmetry for TAx4 SD
TA$\times$4 is an extension of the detection area for ultra-high-energy cosmic ray observations in the Telescope Array experiment. In the TA$\times$4 surface detector analysis, a lateral distribution function (LDF) is used to describe particle density as a function of distance from the air shower axis. The current TA$\times$4 analysis assumes a symmetric LDF around the shower axis; however, this assumption may not be ideal for inclined air showers. Due to differences in the path lengths of air shower particles traveling through the atmosphere, the particle density at ground level may be asymmetric between the upstream and downstream regions of the shower axis. This asymmetry can affect the accuracy of core position determination and primary particle energy estimation. In this study, we develop a functional model to account for air shower asymmetry, aiming to improve the accuracy of reconstruction for the TA$\times$4 surface detector.
Speaker: Ryunosuke SAKAMOTO (Osaka Electro-Communication University) -
23
Measurements of the charge ratio and polarization of cosmic-ray muons with the Super-Kamiokande detector
We present the results of the charge ratio ($R$) and polarization ($P^{\mu}_{0}$) measurements using the decay electron events collected from 2008 September to 2022 June by the Super-Kamiokande detector based on the published results of Phys. Rev. D 110, 082008 (2024). Because of its underground location and long operation, we performed high precision measurements by accumulating cosmic-ray muons. We measured the muon charge ratio to be $R=1.32\pm0.02$ (stat.+syst.) at $E_{\mu}\cos \theta_{\mathrm{Zenith}}=0.7^{+0.3}_{-0.2}$ TeV, where $E_{\mu}$ is the muon energy and $\theta_{\mathrm{Zenith}}$ is the zenith angle of incoming cosmic-ray muons. This result is consistent with the Honda flux model while this suggests a tension with the $\pi K$ model of $1.9\sigma$. We also measured the muon polarization at the production location to be $P^{\mu}_{0}=0.52\pm0.02$ (stat.+syst.) at the muon momentum of $0.9^{+0.6}_{-0.1}$ TeV/c at the surface of the mountain; this also suggests a tension with the Honda flux model of $1.5\sigma$. This is the most precise measurement ever to experimentally determine the cosmic-ray muon polarization near 1 TeV/c. These measurement results are useful to improve the atmospheric neutrino simulations.
Speaker: Yuuki Nakano -
24
Neutrino Search by the Telescope Array Surface Detectors
In this contribution, we present a search strategy for neutrino-induced air showers using the Telescope Array surface detectors (TA SD), focusing on the large zenith angle region. To develop the analysis method, we used Monte Carlo (MC) simulations. In previous TA analyses, the MC generation method was established only for proton showers with zenith angles up to 60 degrees. Therefore, we validated and implemented a new MC generation method specifically for large-zenith-angle neutrino showers. Additionally, we investigated the reconstruction method and developed an optimized approach for large-zenith-angle neutrinos. Using the generated MC, we explored a method to distinguish neutrino showers from proton showers. In this talk, we introduce this new neutrino search method for the TA experiment. This contribution shows the recent progress of neutrino searching.
Speaker: Kaoru Takahashi -
25
Photo nuclear reactions and decay observation for UHECRs (PANDORA)
There are still many mysteries surrounding Ultra-High Energy Cosmic Rays (UHECRs). However, the components of UHECRs are thought to be light-nuclei and they lose their energy through photo nuclear reactions with cosmic microwave background photons. To understand this, the experiment(PANDORA project) has been conducted.
I will be reporting on experimental results from the PANDORA experiment at RCNP(The University of Osaka).Speaker: Yumaro Suzuki
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11
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Social dinner and networking
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Theory session (Convener: Yutaka Ohira)
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26
Theoretical Modeling for Galactic PeVatrons and Super-knee Cosmic-ray Sources
Sources of PeV Cosmic rays in our Galaxy, Galactic PeVatrons, have been a mystery for a long time. Although supernova remnants were considered to be responsible for production of Galactic cosmic rays up to Knee energy (a few PeV), recent gamma-ray observations and theoretical studies disfavor this paradigm. In this talk, I will talk about alternative scenarios, such as Galactic black holes (micro-quasars, X-ray binaries) and peculiar transients (interaction-powered supernovae, binary neutron star mergers), as sources of Knee energy and super-Knee cosmic rays. I will discuss possible observational features to test these scenarios.
Speaker: Shigeo Kimura (Tohoku University) -
27
Sources of Ultrahigh-Energy Cosmic-Ray Nuclei and Multimessenger Implications
Ultrahigh-energy cosmic rays (UHECRs) may be largely nuclei, which gives interesting implications for their sources. We discuss the particle reacceleration model of active galactic nuclei and related multimessenger signatures. If time is allowed, we briefly review models of collapsars and compact binary mergers
Speaker: Kohta Murase (Penn State University) -
28
Search for magnetar-connected cosmic ray PeVatrons
Luminous Supernova remnants (SNRs) and pulsar wind nebulae (PWNe) may be a promising manifestation of cosmic ray (CR) PeVatrons (E>1PeV=1e15 eV) and acceleration mechanism(s) at nonrelativistic and relativistic shocks. In the both cases we expect also high luminosities in synchrotron (from the radio- to the X-ray band) as well as in high-energy (HE, ε > 100 MeV) and very high-energy (VHE, ε > 100 GeV) gamma-ray emission. Both hadronic and leptonic scenarios are expected to contribute to the non-thermal emission from such SNRs and PWNe.
Central engines of luminous Supernova can be connected with fast-rotating new-born fast rotating magnetars with total rotational energy of order of 1e52 ergs and magnetic fields of order of 1e15 G. may serve as a cosmic ray EeVatrons (E>1EeV=1e18 eV).
In magnetar SGR1900+14 sky region a few VHE gamma-ray sources are observed: the unidentified extended Fermi-LAT HE source 4FGL J1908.6+0915e, the extended VHE H.E.S.S. source candidate HOTS J1907+091, and the point-like HAWC TeV source 3HWC J1907+085. As a potential counterpart SNR G42.8+06 is considered. In our previous publications we showed that recently discovered in magnetar SGR1900+14 sky region SNR candidates G043.023+0.762 and G043.070+0.558, at distances of 3.8 kpc and 2.7 kpc respectively, could also be potential sources of observed emission. But very recently the SARAO MeerKAT 1.3 GHz Galactic Plane Survey discovers unidentified extended source G43.025+0.777 with angular radius of 0.016, centered on the magnetar SGR1900+14 position. We consider this new source as a SNR created by magnetar-connected Supernova outburst and build up a hadronic model of observed multiwave (from radio- to VHE gamma-ray) emission from magnetar-supported luminous Supernova remnant.
The work of BH was supported by the National Research Foundation of Ukraine under project No. 2023.03/0149.Speaker: Anastasiia Sokareva (Taras Shevchenko University of Kyiv) -
29
Extremely-energetic cosmic rays with GCOS
Extremely energetic cosmic rays (ExECRs) hold strong potential for determining the origin of extra-galactic cosmic rays. Their interactions with the cosmic microwave background restrict their horizon enough that their propagation can be considered local, unaffected by cosmological evolution. Furthermore, the deflections caused by extra-galactic magnetic fields (EGMFs) are reduced for ExECRs, allowing a stronger correlation between arrival direction and source location. From the theoretical point of view, these ExECRs require methods that are fast and efficient enough to enable event-by-event estimation of the likely distance and direction of origin.
Employing a stochastic analytic framework for describing cosmic ray interactions with analytic probability distributions, the potential for GCOS to uncover the origins of extra-galactic cosmic rays is evaluated. The probability distributions for the origin distance and angular deviation are shown for a number of source-observed nuclei combinations. The composition and angular resolutions needed to separate these hypothesis are contrasted with the planned specifications for GCOS. The framework is implemented in a package called CRISP (Cosmic Ray Interactions for Stochastic Propagation) in preparation for release to the community soon.
Speaker: Leonel Morejon (Wuppertal University) -
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Can Relativistic Shock Waves Accelerate Cosmic Rays via the First-Order Fermi Process?
Cosmic rays (CRs) with energies around 10$^{18}$ eV are generally believed to originate outside our galaxy. If such extragalactic CRs are accelerated by first-order Fermi acceleration, due to their large energy, the shock velocity must be very close to the speed of light, implying relativistic shock waves. However, previous studies have pointed out that the acceleration efficiency at relativistic shocks is typically very low, making it difficult to reach ultra-high energies.
To accelerate CRs by relativistic shocks, we need strong turbulence. We consider that such turbulence can be generated when a shock propagates into the inhomogeneous media. To test this scenario, we performed 3D relativistic MHD simulations and confirmed that turbulence is indeed produced under these conditions. In addition, by performing the test-particle simulations, we found that CRs are accelerated by a relativistic shock wave thanks to the turbulence. We will discuss the conditions for efficient CR acceleration.Speaker: Kanji Morikawa
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26
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Detector session (Convener: Yuichiro Tameda)
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31
Surface detectors: a solution for large exposure Observatories?
I will present possible detector solutions for a large-area Observatory with an emphasis on water-Cherenkov detectors and scintillators. The challenges to overcome are summarized and the usage of PEPS as a prototype array is discussed in the last part of the talk.
Speaker: Ioana Maris -
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Considerations for the next-generation fluorescence detectors
Cosmic rays with energies above 1 EeV, known as ultra-high-energy cosmic rays (UHECRs), have been extensively studied by the Pierre Auger Observatory (Auger) and the Telescope Array experiment (TA). Nevertheless, the interpretation of results from Auger and TA remains controversial due to low statistics.
To address this challenge, the Global Cosmic-Ray Observatory (GCOS) has been proposed. GCOS aims to achieve an order-of-magnitude increase in exposure compared to current observatories, enabling the rapid confirmation of existing findings and facilitating detailed measurements of the energy spectrum, mass composition, and arrival directions of UHECRs.
This contribution focuses on the role of atmospheric fluorescence detectors in next-generation UHECR observations. I present the physics motivations, highlight recent developments in proposed detector designs, and examine systematic uncertainties associated with current instruments. The performance requirements and technical challenges for fluorescence detection to meet the goals of GCOS are also discussed.
Speaker: Shunsuke Sakurai (Osaka Metropolitan University) -
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Low-Elevation Telescopes for GCOS and Neutrino Searches
We summarize the advantages of a central low-elevation fluorescence telescope for detecting air showers over large distances in GCOS. Furthermore, we discuss prospects for operating a prototype at the Pierre Auger Observatory to detect Cherenkov light from neutrino-induced showers originating in the Andes.
Speaker: Michael Unger (Karlsruhe Institute for Technology) -
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Advances in Radio Detection of Cosmic Rays
It is now well established that extensive air showers induced by cosmic rays produce coherent radio emission, enabling the observation of cosmic rays through radio signals. Thanks to recent technological advances and the sustained efforts of the community, radio detection of cosmic rays has developed into a mature and increasingly reliable technique. Radio detectors are also expected to play a central role in next-generation cosmic-ray observatories such as GCOS. In this talk, I will review the current status and recent progress of cosmic-ray observations with radio detectors, highlighting key achievements and future prospects.
Speaker: Hitoshi Oshima (ICRR, the University of Tokyo) -
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Discussion
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31
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Poster session, Discussion, information exchange and collaborative work 2
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Science goal session (Convener: Hiroaki Menjo)
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Paving the way towards a successful GCOS proposal - Thoughts from an Auger perspectiveSpeakers: Ralph Richard Engel (KIT - Karlsruhe Institute of Technology (DE)), Ralph Richard Engel (KIT - Karlsruhe Institute of Technology (DE))
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Forward Hadron Production and Implications for Cosmic Ray Physics with the FASER Experiment at LHC
The Large Hadron Collider (LHC) is not only the most powerful particle accelerator ever constructed but also a unique source of intense, high-energy neutrino beams of all flavors, predominantly emitted in the forward direction. After nearly 15 years of operation, the FASER experiment achieved the first detection of neutrinos produced in proton–proton collisions, marking the advent of collider neutrino physics as a new research frontier. The TeV-scale neutrino flux generated at the LHC enables studies of the highest-energy neutrinos ever produced under controlled laboratory conditions. This opens novel opportunities to investigate neutrino interactions, probe strong-interaction dynamics in previously inaccessible kinematic regimes, and explore scenarios of physics beyond the Standard Model (BSM). These measurements also carry significant implications for astroparticle physics, providing essential input for addressing open questions about the origin and production mechanisms of high-energy neutrinos in astrophysical environments. With the recent results, ongoing and future neutrino experiments at the LHC will play a central role in advancing our understanding of QCD, neutrino properties, and potential new physics. This review summarizes the current status, highlights the initial experimental results, and discusses future prospects for collider neutrino studies by FASER experiment at the LHC.
Speaker: Tomohiro Inada (Kyushu University (JP)) -
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Coordinated UHECR Observations and Global Synergies: perspective and insights from the JEM-EUSO Program
In the last decade, the JEM-EUSO Collaboration has conducted a series of balloon-borne and space-based missions, demonstrating the feasibility of observing UHECRs from space, along with its specific strengths and limitations. As the GCOS initiative develops, we see an opportunity for the international UHECR community to constructively articulate a shared vision and build momentum around its main scientific goals, including connections with adjacent domains in astroparticle physics and interdisciplinary research.
Without interfering with ongoing efforts, we are glad to offer insights from the JEM-EUSO program in support of a global reflection and coordinated strategy — identifying complementarities, clarifying respective strengths, and contributing to a common roadmap. This is in the spirit of the recent Snowmass white paper (Coleman et al., 2023), which we believe can be further developed to raise awareness of the importance of the field and reinforce the case for UHECR studies as a key pillar of next-generation multi-messenger astronomy.
Speaker: Etienne PARIZOT -
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Prospects for Deep-Learning-Based Mass Reconstruction of Ultra-High-Energy Cosmic Rays using Simulated Air-Shower Profiles
The determination of ultra-high-energy cosmic ray (UHECR) mass composition is crucial to understanding their origins, but traditional observables like $X_{\mathrm{max}}$ have limited event-by-event resolution due to their high random component.
In this contribution, we describe the development of a convolutional neural network (CNN) to directly predict the logarithm of the primary mass number ($\ln A$), using the full longitudinal energy-deposit profile of simulated extensive air showers with the goal of improving the composition sensitivity of fluorescence telescopes.
We trained and validated our model on a large suite of simulated showers, generated with CONEX and EPOS-LHC, covering nuclei from $A = 1$ to $61$, sampled uniformly in $\ln A$.
Our network achieves a mean absolute error better than 0.4 in $\ln A$ on unseen test showers with a resolution in $\ln A$ ranging between 1.5 for protons and 1 for iron under realistic and variable noise conditions, outperforming the predictive power of $X_{\mathrm{max}}$, $N_\mu$ or any other known observable.
Our results illustrate that, at least in simulations, the full shower profile contains latent composition-sensitive features which have as much discriminating power as $X_{\mathrm{max}}$.
This performance is only mildly degraded when predictions are made on simulations using the Sibyll-2.3d hadronic interaction model, which was not used in training, showing these features are robust against model choice.
These results suggest that full-profile analysis by machine-learning approaches could significantly enhance real-data composition sensitivity in fluorescence telescope data.Speakers: Dr Eric Mayotte (Colorado School of Mines), Eric Mayotte (Colorado School of Mines) -
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DEASA: Shower rates Monitoring System with Space Weather Detection at Low Latitudes and Portable muon telescope studies solar correlations with cosmic muons at Agra
See material
Speaker: Dr sonali bhatnagar
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36
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Outreach and education session (Convener: Yuko Ikkatai)
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Online Support for Cosmic Ray Research by High School Students and the Creation of International Collaborative Opportunities
At Accel Kitchen, we support cosmic ray and particle physics research projects conducted by junior and senior high school students, primarily in Japan.
Our approach centers on providing students with self-assembled cosmic ray detectors delivered directly to their homes. Using these instruments, students engage in year-long, data-driven research based on original themes. Topics have ranged from comparing cosmic ray intensities at different altitudes—including measurements at the summit of Mt. Fuji—to estimating ceiling thickness via muon transmission rates and detecting Forbush decreases. A single detector has enabled a wide variety of such exploratory studies.These research activities are supported online by over 20 university student mentors, enabling participants to conduct rigorous scientific investigations. Each year, students deliver more than 50 conference presentations, and in the 2023 academic year, two peer-reviewed journal articles were published based on their work.
Beyond Japan, Accel Kitchen has extended its program by sending detectors to countries including Argentina and Thailand, fostering both local scientific inquiry and international collaboration among students. Since 2024, Accel Kitchen has led the IPPOG Global Cosmic Group, a network of outreach organizations from over 11 countries, to promote broader global partnerships in cosmic ray education and exploration.
In addition to online collaborations, students have taken part in on-site international research campaigns. In 2024, they participated in gamma-ray observations during thunderstorms at the Langmuir Laboratory in the United States, conducted beam experiments at CERN in Switzerland, and performed mountain-based measurements at Doi Inthanon in Thailand.
In this presentation, we introduce the structure of our support network and highlight examples of student-led cosmic ray research enabled by this model.
Speaker: Kazuo Tanaka -
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Visualization of Cosmic Ray Air Showers in Virtual Reality
Cosmic ray air showers are magnificent and mysterious high-energy phenomena that occur frequently in our surroundings, but they are invisible to the human eye. We have developed tools to visualize them using VR headsets and web browsers on smartphones and tablets, and have applied them to science museums, elementary school education, and university open campuses. Educational benefits of classes conducted at two elementary schools are analyzed based on the AIDMA model. We will discuss the details of this visualization tool, its operational performance, and its educational effects.
Speaker: Daisuke Ikeda (Kanagawa University) -
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Group photo session
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41
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Discussion, Summary and Closing (Convener: Toshihiro Fujii)
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