Astroparticle Physics最新文献

{"title":"In-ice Askaryan emission from air showers: Implications for radio neutrino detectors","authors":"Alan Coleman ,&nbsp;Christian Glaser ,&nbsp;Ryan Rice-Smith ,&nbsp;Steven Barwick ,&nbsp;Dave Besson","doi":"10.1016/j.astropartphys.2025.103136","DOIUrl":"10.1016/j.astropartphys.2025.103136","url":null,"abstract":"<div><div>One of the most promising techniques for detecting ultra-high energy neutrinos involves the use of radio antennas to observe the 10–1000<!--> <!-->MHz radiation generated by the showers that neutrinos induce in large volumes of ice. The expected neutrino detection rates of one neutrino or less per detector station per 10 years make the characterization of backgrounds a priority. The largest natural background comes from ultra-high energy cosmic rays which are orders of magnitude more abundant than neutrinos. Particularly crucial is the understanding of geometries in which substantial energy of the cosmic-ray-induced air shower is deposited in the ice giving rise to a compact in-ice shower close to the ice surface. We calculated the radio emission of air-shower cores using the novel CORSIKA 8 code and found it to be similar to the predictions for neutrino-induced showers. For the first time, we calculated the detection rates for <span><math><mi>O</mi></math></span>(100<!--> <!-->m) deep antennas yielding 10–100 detections per year and detector station, which makes this a useful calibration source as these downward-going signals can be differentiated from neutrino-induced showers based on the signal arrival direction. However, the presence of reflection layers in the ice confuses the arrival directions, which makes this a potentially important background. We review the existing information on reflecting layers in the South Pole glacier and, for the first time, quantify the corresponding rate of reflected air-shower signals for the proposed IceCube-Gen2 radio array and discuss mitigation strategies. The reflectivity of the layers is the dominant uncertainty resulting in rate predictions of much less than one detection to several detections per year for IceCube-Gen2 if not mitigated.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"172 ","pages":"Article 103136"},"PeriodicalIF":4.2,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144205523","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":"Characterization and absolute calibration of R11265 multi-anode photomultiplier tubes for the JEM-EUSO space and balloon program: II. Application to the EUSO-SPB2 photodetection modules","authors":"D. Trofimov ,&nbsp;E. Parizot ,&nbsp;P.A. Klimov ,&nbsp;A.A. Belov ,&nbsp;A. Creusot ,&nbsp;D. Allard ,&nbsp;B. Baret ,&nbsp;M. Battisti ,&nbsp;S. Blin ,&nbsp;M. Casolino ,&nbsp;T. Ebisuzaki ,&nbsp;G. Filippatos ,&nbsp;E. Msihid ,&nbsp;A. Murashov ,&nbsp;A.V. Olinto ,&nbsp;G. Osteria ,&nbsp;G. Prévôt ,&nbsp;J. Szabelski ,&nbsp;Y. Takizawa ,&nbsp;L. Wiencke","doi":"10.1016/j.astropartphys.2025.103131","DOIUrl":"10.1016/j.astropartphys.2025.103131","url":null,"abstract":"<div><div>The fluorescence camera of the EUSO-SPB2 mission is the last and most advanced implementation of the technology developed within the JEM-EUSO (Joint Exploratory Missions for an Extreme Universe Space Observatory) collaboration to study ultra-high-energy cosmic rays (UHECRs), extensive atmospheric showers and transient luminous events from space. It consists of three photodetection modules, each hosting nine elementary cells with 36 multi-anode photomultiplier tubes (MAPMTs), for a total of 6912 pixels. The associated electronics was designed to operate in single photon counting mode. In this paper, we apply the calibration techniques presented in the accompanying paper (Paper I) to characterize the photodetectors of the EUSO-SPB2 fluorescence camera. In particular, we determine the photodetection efficiency and physical size of each pixel. We find an average efficiency of <span><math><mo>∼</mo></math></span>32%. We also examine its dependence with high voltage and photon wavelength, and determine the double pulse resolution of the different channels, of the order of 10 ns.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"172 ","pages":"Article 103131"},"PeriodicalIF":4.2,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144242552","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":"Definitive evidence of cosmic γ-ray flux reduction during solar eclipse totality: Observations from the 22 July 2009 eclipse in India","authors":"Pranaba K. Nayak ,&nbsp;Shashi R. Dugad ,&nbsp;Sunil K. Gupta ,&nbsp;Atul Jain ,&nbsp;Indranil Mazumdar ,&nbsp;Pravata K. Mohanty ,&nbsp;Supriya Das ,&nbsp;Sanjay K. Ghosh ,&nbsp;Dhruba Gupta ,&nbsp;Sibaji Raha ,&nbsp;Swapan K. Saha ,&nbsp;Sumana Singh ,&nbsp;Arunava Bhadra","doi":"10.1016/j.astropartphys.2025.103122","DOIUrl":"10.1016/j.astropartphys.2025.103122","url":null,"abstract":"<div><div>Over the past quarter century, many attempts have been made to observe an expected inverted Gaussian decrease in the low-energy <span><math><mi>γ</mi></math></span>-ray flux during total solar eclipses, coinciding with the point of totality. However, these studies have produced varied results. Here, we present an experimental setup optimized for cosmic <span><math><mi>γ</mi></math></span>-ray collection while minimizing terrestrial interference. Using four large-volume NaI(Tl) scintillation detectors, we collected <span><math><mi>γ</mi></math></span>-ray flux data during the total solar eclipse of 22 July 2009 from two geographically distinct locations in India: Indore and Siliguri. The detectors were elevated above the ground to further reduce signal contamination by terrestrial <span><math><mi>γ</mi></math></span>-rays, enabling the measurement of flux before, during, and after the eclipse visible from these sites. Despite the careful setup, varying levels of radon daughters in the rain during the eclipse period complicated the spectral analysis. To address this, we developed a RooFit-based method that combines exponential and Gaussian functions to generate unified energy spectra, accounting for temporal variations and the effects of rain. Furthermore, we developed a novel method to isolate the true background from rain-induced interference, revealing a <span><math><mo>∼</mo></math></span>6% reduction in <span><math><mi>γ</mi></math></span>-ray flux during totality at both sites. With improvements in the experimental setup, modelling, and innovative data analysis, this study establishes a foundational approach for future total solar eclipse experiments.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"171 ","pages":"Article 103122"},"PeriodicalIF":4.2,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143948073","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":"Gamma-ray background from rock: Studies for a next-generation dark matter experiment based on liquid xenon","authors":"J.K. Tranter ,&nbsp;V.A. Kudryavtsev ,&nbsp;P.R. Scovell","doi":"10.1016/j.astropartphys.2025.103119","DOIUrl":"10.1016/j.astropartphys.2025.103119","url":null,"abstract":"<div><div>Rare event experiments, such as those targeting dark matter interactions and neutrinoless double beta (0<span><math><mrow><mi>ν</mi><mi>β</mi><mi>β</mi></mrow></math></span>) decay, should be shielded from gamma-rays that originated in rock. This paper describes the simulation of gamma-ray transport through the water shielding and assessment of the thickness needed to suppress the background from rock down to a negligible level. This study focuses on a next-generation xenon observatory with a wide range of measurements including the search for Weakly Interacting Massive Particles (WIMPs) and 0<span><math><mrow><mi>ν</mi><mi>β</mi><mi>β</mi></mrow></math></span> decay of ¹³⁶Xe. Our findings indicate that the gamma-ray background is unlikely to persist through analysis cuts in the WIMP energy range (0 - 20 keV) after 3.5 m of water, complemented by 0.5 m of liquid scintillator. For 0<span><math><mrow><mi>ν</mi><mi>β</mi><mi>β</mi></mrow></math></span> decay, a background below 1 event in 10 years of running can be achieved with a fiducial mass of 39.3 tonnes. Furthermore, for typical radioactivity levels of 1 Bq kg⁻¹ of ²³²Th and ²³⁸U we have studied the effect of reducing the water shielding by 1 m, resulting in a reduced fiducial mass of 19.1 tonnes for 0<span><math><mrow><mi>ν</mi><mi>β</mi><mi>β</mi></mrow></math></span> decay and still a negligible background for WIMP search. The paper also presents the measurements of radioactivity in rock in the Boulby mine, which hosted several dark matter experiments in the past and is also a potential site for a future dual-phase xenon experiment. The measurements are used to normalise simulation results and assess the required shielding at Boulby.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"171 ","pages":"Article 103119"},"PeriodicalIF":4.2,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144099723","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":"A proposed deep sea Neutrino Observatory in the Nanhai","authors":"Huiming Zhang,&nbsp;Yudong Cui,&nbsp;Yunlei Huang,&nbsp;Sujie Lin,&nbsp;Yihan Liu,&nbsp;Zijian Qiu,&nbsp;Chengyu Shao,&nbsp;Yihan Shi,&nbsp;Caijin Xie,&nbsp;Lili Yang","doi":"10.1016/j.astropartphys.2025.103123","DOIUrl":"10.1016/j.astropartphys.2025.103123","url":null,"abstract":"<div><div>Over the past ten years, several breakthroughs have been made in multi-messenger astronomy. Thanks to the IceCube Neutrino Observatory, the detection of astrophysical neutrinos was proved to be practical. However, due to the limited statistics and field of view, only a few sources have been associated with IceCube neutrinos, making new and larger neutrino telescopes necessary. We propose the NEutrino Observatory in the Nanhai (NEON), located in the South China Sea to be complementary for the global neutrino detectors. This proposal describes the design and layout of the array and reports on comprehensive simulations conducted to assess its performance. The NEON project, with a volume of 10 km<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span>, achieves an angular resolution of 0.1 ° at 100 TeV. With 10 years of operation, the project’s 5<span><math><mi>σ</mi></math></span> sensitivity is estimated as <span><math><mrow><msup><mrow><mi>E</mi></mrow><mrow><mn>2</mn></mrow></msup><mi>Φ</mi><mo>∼</mo><mn>3</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>10</mn></mrow></msup></mrow></math></span> GeV cm⁻² s⁻¹ for a source spectrum index of -2. We found that the variation in depth from 1700 to 3500 meters does not significantly influence the sensitivity to steady sources.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"171 ","pages":"Article 103123"},"PeriodicalIF":4.2,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143948074","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":"Reconstruction of inclined extensive air showers using radio signals: From arrival times and amplitudes to direction and energy","authors":"Marion Guelfand ,&nbsp;Valentin Decoene ,&nbsp;Olivier Martineau-Huynh ,&nbsp;Simon Prunet ,&nbsp;Matías Tueros ,&nbsp;Oscar Macias ,&nbsp;Aurélien Benoit-Lévy","doi":"10.1016/j.astropartphys.2025.103120","DOIUrl":"10.1016/j.astropartphys.2025.103120","url":null,"abstract":"<div><div>Radio detection is now an established technique for the study of ultra-high-energy (UHE) cosmic rays with energies above <span><math><mrow><mo>∼</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>17</mn></mrow></msup></mrow></math></span> <!--> <!-->eV. The next-generation of radio experiments aims to extend this technique to the observation of UHE earth-skimming neutrinos, which requires the detection of very inclined extensive air showers (EAS). In this article we present a new reconstruction method for the arrival direction and the energy of EAS. It combines a point-source-like description of the radio wavefront with a phenomenological model: the Angular Distribution Function (ADF). The ADF describes the angular distribution of the radio signal amplitude in the 50–200<!--> <!-->MHz frequency range, with a particular focus on the Cherenkov angle, a crucial feature of the radio amplitude pattern. The method is applicable to showers with zenith angles larger than <span><math><mrow><mn>60</mn><mo>°</mo></mrow></math></span>, and in principle up to neutrino-induced showers with up-going trajectories. It is tested here on a simulated data set of EAS induced by cosmic rays. A resolution better than 4 arc-minutes (<span><math><mrow><mn>0</mn><mo>.</mo><mn>07</mn><mo>°</mo></mrow></math></span>) is achieved on arrival direction, as well as an intrinsic resolution of 5% on the electromagnetic energy, and around 15% on the primary energy.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"171 ","pages":"Article 103120"},"PeriodicalIF":4.2,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144115553","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":"Optimization of singly-charged particles identification with the AMS02 RICH detector by a machine learning method","authors":"Georgi Vasilev,&nbsp;Galina Vankova-Kirilova,&nbsp;Galina Bozhkova","doi":"10.1016/j.astropartphys.2025.103134","DOIUrl":"10.1016/j.astropartphys.2025.103134","url":null,"abstract":"<div><div>AMS-02 is a detector currently in operation onboard the International Space Station (ISS). One of the main scientific goals of the spectrometer is the measurement of charged particle fluxes. The detector design makes possible the identification of particles and antiparticles by precise measurement of particle momentum in the AMS-02 Silicon Tracker, and velocity in the Cherenkov (RICH) detector. The RICH is able to measure the isotopic composition of the light elements (up to charge <em>Z</em> = 5) in the kinetic energy range from a few GeV/n to about 10 GeV/n. However, the velocity reconstruction for charge 1 particles is particularly challenging due to the low number of photons they produce in the RICH detector which can lead to wrong event reconstruction. In this paper, we show the high potential of the Multilayer Perceptron deep learning model (MLP-BFGS) for identification of signal and the background due to interactions inside the AMS-02 detector, and to significantly improve particle identification by its mass.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"171 ","pages":"Article 103134"},"PeriodicalIF":4.2,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144099722","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":"Corrigendum to “Axionic quantum fluctuations, dark energy, and the Hubble tension” [Volume 169, July 2025, 103111 Astroparticle Physics]","authors":"L. Acedo","doi":"10.1016/j.astropartphys.2025.103121","DOIUrl":"10.1016/j.astropartphys.2025.103121","url":null,"abstract":"","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"171 ","pages":"Article 103121"},"PeriodicalIF":4.2,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143922860","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":"Characterization and absolute calibration of R11265 multi-anode photomultiplier tubes for the JEM-EUSO space and balloon program, I: Methods and generic features","authors":"E. Parizot ,&nbsp;D. Trofimov ,&nbsp;S. Blin ,&nbsp;A. Creusot ,&nbsp;D. Allard ,&nbsp;B. Baret ,&nbsp;P. Barrillon ,&nbsp;M. Battisti ,&nbsp;A.A. Belov ,&nbsp;C. Blaksley ,&nbsp;P. Gorodetzky ,&nbsp;P.A. Klimov ,&nbsp;E. Msihid ,&nbsp;L. Piotrowski ,&nbsp;G. Prévôt ,&nbsp;J. Szabelski ,&nbsp;C. de la Taille","doi":"10.1016/j.astropartphys.2025.103112","DOIUrl":"10.1016/j.astropartphys.2025.103112","url":null,"abstract":"<div><div>Over the last decade, the Joint Exploratory Missions for an Extreme Universe Space Observatory (JEM-EUSO) collaboration has developed several balloon and space missions implementing different versions of a dedicated camera based on multi-anode photomultiplier tubes (MAPMTs) used in single photoelectron counting mode, in the near ultra-violet. In this paper, we present the experimental techniques developed to calibrate these MAPMTs and determine their main characteristics, relevant to the JEM-EUSO applications. Our results include the absolute calibration of the MAPMTs in both full illumination and localized illumination modes, the measurement of the so-called s-curves and their fitting with a newly developed fitting formula, the study of cross-talk and residual non-Poissonian behaviour, the determination of the physical size of the individual pixels, the wavelength dependence of the photodetection efficiency, the characterization of the pile-up effect and the determination of the corresponding double pulse resolution using a dedicated readout implementing the SPACIROC-3 Application-specific integrated circuit. These techniques allowed us to identify generic features of the MAPMTs of type R11265 from Hamamatsu, including the occasional occurrence of multiple counting of single photons, which the Hamamatsu company was then able to correct and eliminate. We find that the reliability, high-efficiency and homogeneity of these MAPMTs is well suited for the multi-disciplinary scientific objectives of the JEM-EUSO collaboration. The application of our techniques to the characterization and absolute calibration of the fluorescence camera of the EUSO-SPB2 mission is presented in an accompanying paper.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"171 ","pages":"Article 103112"},"PeriodicalIF":4.2,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143937096","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":"Axionic quantum fluctuations, dark energy, and the Hubble tension","authors":"L. Acedo","doi":"10.1016/j.astropartphys.2025.103111","DOIUrl":"10.1016/j.astropartphys.2025.103111","url":null,"abstract":"<div><div>The cosmological constant is now a fundamental ingredient of the standard ΛCDM model, and its value is constrained by concordance with empirical data. Despite its importance in modern cosmology, we still do not understand its origin. A naive calculation of the contribution of the quantum vacuum fluctuations to vacuum energy (considering it to be the source of the cosmological constant) yields predictions 120 orders of magnitude larger than observations. This poses one of the most celebrated unsolved problems in physics and cosmology. This work discusses a model of quantum-thermal fluctuations of the cosmic microwave background with a Planck factor. Fluctuations of a bosonic field are studied, and we show that they could match the vacuum energy density if they correspond to an axionic field with a particle rest mass in the range of a fraction of a meV. This mass range is in agreement with present bounds on the mass of the Peccei–Quinn axions arising from the spontaneous symmetry breaking that explains CP conservation in strong interactions, as well as estimations of the mass of axions in the galactic halo and experiments on Shapiro step anomalies using Josephson junctions. We also show that this model can clarify the Hubble tension debate, i.e., the statistically significant discrepancy between measurements of the Hubble parameter based upon the cosmic microwave background and those using low redshift observations.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"169 ","pages":"Article 103111"},"PeriodicalIF":4.2,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143767551","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}