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HAWC Collaboration(Alfaro, R. et al), & Coutiño de Leon, S. (2025). Study of the IC 443 Region with the HAWC Observatory. Astrophys. J., 992(1), 22–16pp.
Abstract: Supernova remnants are one potential source class considered a PeVatron (i.e., capable of accelerating cosmic rays above PeV energies). The shock fronts produced after the explosion of the supernova are ideal regions for particle acceleration. IC 443 is a supernova remnant that has been studied extensively at different wavelengths. Using 2966 days of gamma-ray data from the High Altitude Water Cherenkov (HAWC) observatory, we study the emission of IC 443 with the objective of finding signatures of cosmic-ray acceleration at the PeV scale. Using a maximum likelihood method, we find a point source located at (alpha = 94 .degrees 42, delta = 22 .degrees 35) that we associate with IC 443. The measured spectrum is a simple power law with an index of -3.14 +/- 0.18, which is consistent with previous TeV observations. Although we cannot confirm that IC 443 is a hadronic PeVatron, we do not find any sign that the spectrum has a cutoff at tens of TeV energies, with the spectrum extending to similar to 30 TeV. Furthermore, we also find a new extended component in the region whose emission is described by a simple power law with an index of -2.49 +/- 0.08 and which we call HAWC J0615+2213. While we show evidence that this new source might be a new TeV halo, we defer a detailed analysis of this new source to another publication.
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D'Amen, G. et al, & Solaz, C. (2025). First stave results towards mitigating sensor fracturing with interposers in the ATLAS ITk strips barrel. J. Instrum., 20(9), P09025–25pp.
Abstract: At the conclusion of Run 3 of the Large Hadron Collider (LHC) at CERN, the accelerator complex will be upgraded to the High-Luminosity LHC (HL-LHC), allowing it to increase the dataset sizes of LHC experiments by about a factor of 20. This significant increase in dataset size will improve the sensitivity and precision of all physics analyses from LHC experiments, but will come with a more challenging data-taking environment. In order to handle this, the ATLAS detector will undergo a substantial upgrade, including an upgrade of its inner tracker to an all-silicon tracker called the Inner Tracker (ITk), made of pixel and strip sub-detectors. During the pre-production phase of the ITk strips, it was discovered that thermally cycling modules loaded onto local support structures led to physical fractures in silicon sensors due to the induced thermal stress. This is understood to be the result of several factors, including the difference in coefficients of thermal expansion between the different module layers, and the close proximity of the module electrical components. Several mitigation strategies were tested to reduce the rate of module fracturing. This paper describes the assembly setup, testing setups, and electrical testing results of ITk strips barrel modules loaded onto local support structures. 69 of 70 modules with an in-built additional kapton layer were found to survive testing down to-70 degrees C.
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Molina, J., Richard, E., Secchia, G., Stalder, D., Bertoli, M., Trepowski, C., et al. (2025). Measurements of Forbush Decrease Events at the Center of the South Atlantic Magnetic Anomaly With Muon Detectors. Space Weather, 23(10), e2025SW004363–20pp.
Abstract: We present the construction and validation of a low-cost muon detector in Paraguay, located at the center of the South Atlantic Magnetic Anomaly (SAMA), where the geomagnetic cutoff rigidity is 9.63 GV. The detector consists of plastic scintillator plates coupled with silicon photomultipliers for light detection. To verify its performance, we measured the average muon flux rate and investigated its correlation with geomagnetic activity, particularly the disturbance storm time (Dst) index, during the May and October 2024 Forbush Decrease events. Using the Truncated Time-Shift test-a recent statistical method for comparing time-series-we found a strong correlation, indicating our detector reliably measures the muon flux over time. Our measurements also allowed us to resolve the detailed morphology of the Forbush decreases, by comparison with local magnetic field fluctuations. These initial results represent a step forward in ground-level radiation monitoring within the SAMA, and highlight the potential of economical muon detectors as components of early-stage diagnostic systems for space weather forecasting.
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Goyal, N. et al, Gonzalez-Alonso, M., & Rodriguez-Sanchez, A. (2025). Performance of the MORA apparatus for testing time-reversal invariance in nuclear beta decay. Eur. Phys. J. A, 61(10), 221–20pp.
Abstract: The MORA experimental setup is designed to measure the triple-correlation D parameter in the nuclear beta decay of trapped and polarized 23Mg+ and 39Ca+ ions. The D coefficient is sensitive to potential violations of time-reversal invariance – and, via the CPT theorem, to CP violation. The experimental configuration consists of a transparent Paul trap surrounded by a detection setup with alternating beta and recoil-ion detectors. The octagonal symmetry of the detection setup optimizes the sensitivity of positron-recoil-ion coincidence rates to the D correlation, while reducing systematic effects. MORA utilizes an innovative in-trap laser polarization technique. The design and performance of the ion trap and associated optics, lasers and beta and detection system are presented. The recent experimental demonstration of the polarization technique is described.
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Miramontes, A. S., Morgado, J. M., Papavassiliou, J., & Pawlowski, J. M. (2025). A comprehensive approach to the physics of mesons. Eur. Phys. J. C, 85(9), 1055–23pp.
Abstract: We develop an inclusive approach for the self-consistent solution of coupled sets of Bethe-Salpeter and Schwinger-Dyson equations in QCD. This framework allows us to maintain the axial Ward-Takahashi identities of the theory within advanced approximation schemes, such as the skeleton or three-particle irreducible expansions. For this purpose we reformulate the Schwinger-Dyson equation of the axial-vector vertex such that the bulk of its quantum corrections is expressed in terms of an effective vertex, containing an additional gluon. Crucially, this vertex satisfies a symmetry-induced relation of its own, which involves the full quark-gluon vertex. As a result, the Schwinger-Dyson equation reproduces the standard Ward-Takahashi identity satisfied by the axial-vector vertex. Consequently, the known relation between the quark mass function and the wave function of the pion in the chiral limit is duly fulfilled. The present approach offers valuable insights into the interplay between symmetry and dynamics, and provides a practical path towards computations of hadron physics within sophisticated approximations. In particular, the one-loop dressed truncation of the key dynamical equations, including that of the quark-gluon vertex, is shown to be completely compatible with the required symmetry relations. Further extensions and potential phenomenological applications of the developed framework are briefly discussed.
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