Astroparticle Physics最新文献

{"title":"Effects of Bethe–Heitler pair production in ultraluminous X-ray sources","authors":"Gustavo E. Romero,&nbsp;Lucas M. Pasquevich,&nbsp;Leandro Abaroa","doi":"10.1016/j.astropartphys.2025.103173","DOIUrl":"10.1016/j.astropartphys.2025.103173","url":null,"abstract":"<div><div>Some black holes in X-ray binaries accrete at rates far above the Eddington limit. In this supercritical regime, photons are trapped in a radiation-dominated, geometrically thick disk. The innermost regions form a complex environment of intense radiation, strong magnetic fields, and powerful outflows, where radiation-driven winds expel large amounts of mass. These conditions suppress primary relativistic electrons within the transparent funnel along the black hole’s spin axis. We show that high-energy electrons can instead arise as secondary pairs from Bethe–Heitler interactions between relativistic protons and ambient photons. Using self-similar models of accretion disks with strong winds of ultraluminous X-ray sources (ULXs), we compute particle acceleration via magnetic reconnection and diffusive shocks, evaluate energy losses, and assess the efficiency and spectral imprint of Bethe–Heitler pair production. Our results suggest that secondary pairs can yield nonthermal radiation in the 0.1-100 MeV range with luminosities from <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>34</mn></mrow></msup></mrow></math></span> up to <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>38</mn></mrow></msup></mrow></math></span> erg s⁻¹. This emission could be detectable by future MeV instruments from Galactic ULXs, offering <strong>evidence of relativistic protons</strong> in their inner funnels and revealing misaligned, otherwise hidden, super-Eddington sources in the Milky Way.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"175 ","pages":"Article 103173"},"PeriodicalIF":2.9,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145050580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement of the re-entrant all-electron spectrum by the High-Energy Particle Detector on board the China Seismo-Electromagnetic Satellite","authors":"S. Amoroso ,&nbsp;M. Babu ,&nbsp;S. Bartocci ,&nbsp;R. Battiston ,&nbsp;S. Beolè ,&nbsp;W.J. Burger ,&nbsp;D. Campana ,&nbsp;P. Cipollone ,&nbsp;L. Conti ,&nbsp;A. Contin ,&nbsp;M. Cristoforetti ,&nbsp;C. De Donato ,&nbsp;C. De Santis ,&nbsp;A. Di Luca ,&nbsp;F.M. Follega ,&nbsp;G. Gebbia ,&nbsp;R. Iuppa ,&nbsp;A. Lega ,&nbsp;M. Lolli ,&nbsp;M. Martucci ,&nbsp;P. Zuccon","doi":"10.1016/j.astropartphys.2025.103170","DOIUrl":"10.1016/j.astropartphys.2025.103170","url":null,"abstract":"<div><div>Interactions of primary cosmic rays with residual atmospheric nuclei produce secondary leptons through the decay chain of short-lived pions. Even though generated with an upward direction, a fraction of these secondary electrons and positrons is bent back downward towards the Earth by the geomagnetic field lines (hence they are called re-entrant albedo). In this paper, we report on a new measurement of the re-entrant all-electron differential flux in the energy range 10-100 MeV, performed by the High-Energy Particle Detector (HEPD-01) on board the China Seismo-Electromagnetic Satellite (CSES-01) in the near-equatorial region at about 500 km altitude between 2018 and 2022. This analysis focuses on the re-entrant all-electron spectrum that covers the low energy interval in a geographical region characterized by a substantial lack of recent experimental data and can contribute to a more accurate definition of secondary electron and positron population distribution and refine the radiation models in the Earth’s magnetosphere.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"175 ","pages":"Article 103170"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145027840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crystal Eye: All sky MeV monitor with high precision real-time localization","authors":"R. Aloisio ,&nbsp;U. Atalay ,&nbsp;B. Banerjee ,&nbsp;F.C.T. Barbato ,&nbsp;E. Bissaldi ,&nbsp;M. Branchesi ,&nbsp;F. Capitanio ,&nbsp;E. Casilli ,&nbsp;R. Colalillo ,&nbsp;I. De Mitri ,&nbsp;A. De Santis ,&nbsp;A. Di Giovanni ,&nbsp;M. Fernandez Alonso ,&nbsp;G. Fontanella ,&nbsp;F. Gargano ,&nbsp;F. Garufi ,&nbsp;F. Guarino ,&nbsp;D. Kyratzis ,&nbsp;H. Lima ,&nbsp;F. Loparco ,&nbsp;L. Wu","doi":"10.1016/j.astropartphys.2025.103171","DOIUrl":"10.1016/j.astropartphys.2025.103171","url":null,"abstract":"<div><div>Crystal Eye is a space-based all-sky monitor optimized for the autonomous detection and localization of transients in the 10 keV to 30 MeV energy range, a region where extensive observations and monitoring of various astrophysical phenomena are required. By focusing on the operating environment and its impact on the observation process, we optimized the detector design and assessed its scientific potential. We explored the use of novel techniques to achieve the science goals of the experiment. We assumed the orbit of a potential future mission at approximately 550 km altitude near the equatorial region with a 20° inclination. In such an orbit, the main background contributions for this kind of detector are from different particles and radiation of cosmic origin and secondaries produced by their interaction in the Earth’s atmospheric and geomagnetic environment. We studied the response of Crystal Eye detector in this background environment, using the Geant4 Monte Carlo simulation toolkit. We also calculated other detector performance parameters to estimate its scientific capabilities. The effective area and efficiency of the detector are calculated for low energy <span><math><mi>γ</mi></math></span>-ray sources and used to estimate its sensitivity to short-duration transient sources. The calculation shows a better effective area and sensitivity by several factors compared to existing instruments of similar type. A method is also developed and discussed to estimate the online transient-localization performance of the detector, suggesting a better localization precision by about an order of magnitude than those typically reported by existing <span><math><mi>γ</mi></math></span>-ray monitors. We present here the simulation study and results of an innovative detector design concept that can make a significant contribution in the multi-messenger era. Moreover, this study can be useful as a technical reference for similar future experiments.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"174 ","pages":"Article 103171"},"PeriodicalIF":2.9,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144988006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The influence of the 3D Galactic gas structure on cosmic-ray transport and γ-ray emission","authors":"Andrés Ramírez ,&nbsp;Gordian Edenhofer ,&nbsp;Torsten A. Enßlin ,&nbsp;Philipp Frank ,&nbsp;Philipp Mertsch ,&nbsp;Vo Hong Minh Phan ,&nbsp;Laurin Söding ,&nbsp;Hanieh Zandinejad ,&nbsp;Ralf Kissmann","doi":"10.1016/j.astropartphys.2025.103151","DOIUrl":"10.1016/j.astropartphys.2025.103151","url":null,"abstract":"<div><div>Cosmic rays (CRs) play a major role in the dynamics of the interstellar medium (ISM). Their interactions and transport ionize, heat, and push the ISM thereby coupling different regions of it. The spatial distribution of CRs depends on the distribution of their sources as well as the ISM constituents they interact with, such as gas, starlight, and magnetic fields. Particularly, gas influences CR fluxes and <span><math><mi>γ</mi></math></span>-ray emission. We illustrate the influence of realistic and largely structured 3D gas distributions on CR transport and <span><math><mi>γ</mi></math></span>-ray emission, by studying their correlation using the PICARD code and multiple samples of recent 3D reconstructions of the HI and H2 Galactic gas constituents. We adjust the diffusion coefficient <span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>x</mi><mi>x</mi></mrow></msub></math></span> and Alfvén speed <span><math><msub><mrow><mi>v</mi></mrow><mrow><mtext>A</mtext></mrow></msub></math></span> to reproduce local measurements of B/C abundances and find that these parameters depend non-linearly on the local distribution of gas. When simulating CR transport, the distributions of CR fluxes exhibit energy-dependent structures that vary for all CR species due to their corresponding loss processes. Regions of enhanced secondary (primary) species are spatially correlated (anti-correlated) with the gas density. Furthermore, we show that the morphology of gas clouds alone impacts CR flux predictions. For <span><math><mi>γ</mi></math></span>-ray emission, we observe a high sensitivity of the <span><math><mi>γ</mi></math></span>-ray emissivities to gas structures, as these determine the spatial distributions of hadronic interactions and bremsstrahlung. This way, we have for the first time calculated how well-defined uncertainties in a structured gas model propagate to CR transport and <span><math><mi>γ</mi></math></span>-ray emission.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"174 ","pages":"Article 103151"},"PeriodicalIF":2.9,"publicationDate":"2025-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144886204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulations of astrophysically relevant pair beam instabilities in a laboratory context","authors":"Suman Dey,&nbsp;Günter Sigl","doi":"10.1016/j.astropartphys.2025.103153","DOIUrl":"10.1016/j.astropartphys.2025.103153","url":null,"abstract":"<div><div>The interaction of TeV blazars emitted gamma-rays with the extragalactic background photons gives rise to a relativistic beam of electron–positron (<span><math><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup></mrow></math></span>) pairs propagating through the intergalactic medium, producing a cascade through up-scattering low-energy photons. Plasma instability is considered one of the underlying energy-loss processes of the beams. We employ particle-in-cell (PIC) simulations to study the plasma instabilities of relativistic pair beams propagating in a denser background plasma, using the parameters designed to replicate astrophysical jets under laboratory conditions. In an astrophysical scenario with a broad, dilute beam, electromagnetic instability is suppressed because the beam exhibits momentum anisotropy with a large longitudinal momentum spread compared to its transverse momentum. We find the range of density contrast at which electrostatic modes are dominating over electromagnetic modes with an anisotropic beam in laboratory scales, consistent with the physically relevant conditions for Blazar-induced beams. We have used a broad Cauchy distribution for the beam particles, which is more realistic in representing the non-Maxwellian nature of pair beams, improving upon previous studies. We investigate the interplay between the instability-generated magnetic field and the momentum anisotropy of the beam. We extrapolate the beam energy loss and the angular broadening due to non-linear feedback of instability. We find that the astrophysical beams have lost approximately 4% of their total energy due to instability. Nevertheless, the instability generates a negligible angular broadening for Blazar-induced beams.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"173 ","pages":"Article 103153"},"PeriodicalIF":2.9,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144781261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Antihelium-3 sensitivity for the GRAMS experiment","authors":"J. Zeng ,&nbsp;T. Aramaki ,&nbsp;K. Aoyama ,&nbsp;S. Arai ,&nbsp;S. Arai ,&nbsp;J. Asaadi ,&nbsp;A. Bamba ,&nbsp;N. Cannady ,&nbsp;P. Coppi ,&nbsp;G. De Nolfo ,&nbsp;M. Errando ,&nbsp;L. Fabris ,&nbsp;T. Fujiwara ,&nbsp;Y. Fukazawa ,&nbsp;P. Ghosh ,&nbsp;K. Hagino ,&nbsp;T. Hakamata ,&nbsp;N. Hiroshima ,&nbsp;M. Ichihashi ,&nbsp;Y. Ichinohe ,&nbsp;M. Yoshimoto","doi":"10.1016/j.astropartphys.2025.103152","DOIUrl":"10.1016/j.astropartphys.2025.103152","url":null,"abstract":"<div><div>The Gamma-Ray and AntiMatter Survey (GRAMS) is a next-generation balloon/satellite mission utilizing a Liquid Argon Time Projection Chamber (LArTPC) detector to measure both MeV gamma rays and antinuclei produced by dark matter annihilation or decay. The GRAMS can identify antihelium-3 events based on the measurements of X-rays and charged pions from the decay of the exotic atoms, Time of Flight (TOF), energy deposition, and stopping range. This paper shows the antihelium-3 sensitivity estimation using a GEANT4 Monte Carlo simulation. For the proposed long-duration balloon (LDB) flight program (35 days <span><math><mo>×</mo></math></span> 3 flights) and future satellite mission (2-year observation/10-year observation), the sensitivities become 1.47 × 10⁻⁷ [m<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span> s sr GeV/n]⁻¹ and 1.55 × 10⁻⁹ [m<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span> s sr GeV/n]⁻¹/<span><math><mrow><mn>3</mn><mo>.</mo><mn>10</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>10</mn></mrow></msup></mrow></math></span> [m<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span> s sr GeV/n]⁻¹, respectively. The results indicate that GRAMS can extensively investigate various dark matter models through the antihelium-3 measurements.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"173 ","pages":"Article 103152"},"PeriodicalIF":2.9,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144766732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scintillation characteristics of an undoped CsI crystal at low-temperature for dark matter search","authors":"W.K. Kim ,&nbsp;H.Y. Lee ,&nbsp;K.W. Kim ,&nbsp;Y.J. Ko ,&nbsp;J.A. Jeon ,&nbsp;H.J. Kim ,&nbsp;H.S. Lee","doi":"10.1016/j.astropartphys.2025.103150","DOIUrl":"10.1016/j.astropartphys.2025.103150","url":null,"abstract":"<div><div>The scintillation characteristics of 1<!--> <!-->g undoped CsI crystal were studied by directly coupling two silicon photomultipliers (SiPMs) over a temperature range from room temperature to 86<!--> <!-->K. The scintillation decay time and light output were measured using x-ray and gamma-ray peaks from a ¹⁰⁹Cd radioactive source. An increase in decay time was observed as the temperature decreased from room temperature to 86<!--> <!-->K, ranging from 76<!--> <!-->ns to 605<!--> <!-->ns. The light output also increased, reaching 26.2 ± 1.3 photoelectrons per keV electron-equivalent at 86<!--> <!-->K. Leveraging the significantly enhanced scintillation light output of the undoped CsI crystal at low temperatures, coupling it with SiPMs results in a promising detector for rare event searches. Both cesium and iodine have an odd number of protons, making them suitable targets for probing dark matter-proton spin-dependent interactions. This study evaluates the sensitivity of the proposed detector to such interactions, incorporating the Migdal effect and assuming 200 kg of undoped CsI crystals for dark matter searches. The results indicate that undoped CsI coupled with SiPM can achieve world-competitive sensitivity for low-mass dark matter detection, particularly in the context of dark matter-proton spin-dependent interactions.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"173 ","pages":"Article 103150"},"PeriodicalIF":2.9,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144781260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of the absolute energy scale of the DAMPE calorimeter with the geomagnetic rigidity cutoff method","authors":"JingJing Zang ,&nbsp;Chuan Yue ,&nbsp;Qiang Yuan ,&nbsp;Wei Jiang ,&nbsp;Xiang Li ,&nbsp;Yunlong Zhang ,&nbsp;Cong Zhao ,&nbsp;Fabio Gargano","doi":"10.1016/j.astropartphys.2025.103149","DOIUrl":"10.1016/j.astropartphys.2025.103149","url":null,"abstract":"<div><div>The Dark Matter Particle Explorer (DAMPE) is a satellite-borne detector designed to detect high-energy cosmic ray particles with its core component being a BGO calorimeter capable of measuring energies from <span><math><mo>∼</mo></math></span>GeV to <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mn>100</mn><mo>)</mo></mrow><mspace></mspace><mi>TeV</mi></mrow></math></span>. The 32 radiation lengths thickness of the calorimeter is designed to ensure full containment of showers produced by cosmic ray electrons and positrons (CREs) and <span><math><mi>γ</mi></math></span>-rays at energies below tens of TeV, providing high resolution in energy measurements. The absolute energy scale therefore becomes a crucial parameter for precise measurements of the CRE energy spectrum. The geomagnetic field induces a rapid drop in the low energy spectrum of electrons and positrons, a phenomenon that provides a method to determine the calorimeter’s absolute energy scale. By comparing the cutoff energies of the measured spectra of CREs with those expected from the International Geomagnetic Reference Field model across 4 McIlwain <span><math><mi>L</mi></math></span> bins – which cover most regions of the DAMPE orbit – we find that the calorimeter’s absolute energy scale exceeds the calibration based on Geant4 simulation by <span><math><mrow><mn>1</mn><mo>.</mo><mn>013</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>01</mn><msub><mrow><mn>2</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>0</mn><mo>.</mo><mn>02</mn><msub><mrow><mn>6</mn></mrow><mrow><mi>sys</mi></mrow></msub></mrow></math></span> for energies between 7 GeV and 16 GeV. The absolute energy scale should be taken into account when comparing the absolute CREs fluxes among different detectors.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"173 ","pages":"Article 103149"},"PeriodicalIF":4.2,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144714074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisiting propagation delays of ultra-high-energy cosmic rays from long-lived sources","authors":"Rostom Mbarek ,&nbsp;Damiano Caprioli","doi":"10.1016/j.astropartphys.2025.103148","DOIUrl":"10.1016/j.astropartphys.2025.103148","url":null,"abstract":"<div><div>We revisit the time delay incurred during ultra-high energy cosmic ray (UHECR) propagation over cosmological distances and its potential impact on the correlation between UHECR directions of arrival and long-lived sources (i.e., with duty cycles of order of Myr, such as Active Galactic Nuclei (AGNs) and starburst galaxies), the UHECR chemical composition, and extragalactic magnetic field constraints. We propagate particles in different magnetic field configurations, spanning over an extended range of particle Larmor radii and magnetic field coherence lengths, also including attenuation losses. We conclude that UHECR delays could easily be comparable to (and longer than) AGN duty cycles, effectively erasing the correlation between known AGNs and UHECR anisotropies. We finally consider how strong constraints on the chemical composition of the heaviest UHECRs could enable a better characterization of extragalactic magnetic fields.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"172 ","pages":"Article 103148"},"PeriodicalIF":4.2,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement of cosmic-ray muon flux at CJPL-II","authors":"P. Zhang ,&nbsp;H. Ma ,&nbsp;W. Dai ,&nbsp;M. Jing ,&nbsp;L. Yang ,&nbsp;Q. Yue ,&nbsp;Z. Zeng ,&nbsp;J. Cheng","doi":"10.1016/j.astropartphys.2025.103147","DOIUrl":"10.1016/j.astropartphys.2025.103147","url":null,"abstract":"<div><div>In China Jinping Underground Laboratory (CJPL), the deepest and largest underground laboratory globally, the cosmic-ray muon flux is significantly reduced due to the substantial shielding provided by the overlying mountain. From 2016 to 2020, we measured the muon flux in the second phase of CJPL (CJPL-II) with a plastic scintillator muon telescope system, detecting 161 muon events over an effective live time of 1098 days. The detection efficiency was obtained by simulating the underground muon energy and angular distributions and the telescope system’s response to underground muons. The cosmic-ray muon flux is determined to be (3.03 ± 0.24 (stat) <span><math><mo>±</mo></math></span> 0.18 (sys)) <span><math><mo>×</mo></math></span> 10⁻¹⁰ cm⁻²s⁻¹, which is the lowest among underground laboratories worldwide.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"172 ","pages":"Article 103147"},"PeriodicalIF":4.2,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144522417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}