Proton fluxes inside the South Atlantic Anomaly measured by the High-Energy Particle Detector (HEPD) on board the CSES-01 satellite during the 2018-2021 period

Despite notable improvements made in the last decades, the characterization of the near-Earth proton radiation environment is still incomplete, with major uncertainties affecting the description of high-energy particles ( 50 MeV) in the South Atlantic Anomaly (SAA) region. The High Energy Particle Detector (HEPD) on board the China Seismo-Electromagnetic Satellite (CSES 01), launched on February 2018 on a Low-Earth Orbit and with an altitude of about 507 km, is a light and compact payload suitable for measuring electrons (3-100 MeV), protons (30-300 MeV), and light nuclei (up to a few hundreds of MeV) with a high energy resolution and a wide angular acceptance. Thanks to its good identification performance, it can carry out precise and comprehensive measurement of particle fluxes, including angular information. The observations of HEPD could be fundamental not only for space weather purposes, but because they could help set important constraints on trapping and interaction processes in the Earth’s atmosphere and magnetosphere. Furthermore, they enable the testing and validation of current theoretical and empirical models of the inner radiation belt, like the NASA AP9. In this contribution, we report a preliminary analysis of 30 MeV protons detected inside the SAA region between 2018 and 2021

The High Energy Particle Detector (HEPD-02) for the second China Seismo-Electromagnetic Satellite (CSES-02)

CSES (China Seismo-Electromagnetic Satellite) is a multi-instrumental scientific space program whose objectives are to investigate the near-Earth electromagnetic, plasma and particle environment and to study the seismo associated disturbances in the ionosphere-magnetosphere transition zone, the anthropogenic electromagnetic noise as well as the natural non-seismic electromagnetic emissions, mainly due to tropospheric activity. In particular, the mission aims at confirming the existence of possible temporal correlations between the occurrence of medium and strong magnitude earthquakes and the observation in space of electromagnetic perturbations, plasma variations and precipitation of bursts of high-energy charged particles from the inner Van Allen belt. The first satellite (CSES-01) was launched on 2018, while a second one (CSES-02) is currently under development and its launch is expected by the end of 2022. As in CSES-01, the suite of instruments on-board CSES-02 will comprise a particle detector (HEPD-02, High-energy Particle Detector) to measure the increase of the electron and proton fluxes due to short-time perturbations of the radiation belts induced by solar, terrestrial or anthropic phenomena in the energy range 3-100 MeV for electrons and 30-200 MeV for protons. HEPD-02 comprises a tracker made of CMOS Monolithic Active Pixel Sensors (MAPS), a double layer of crossed plastic scintillators for trigger and a calorimeter, made of a tower of plastic scintillators and a matrix of inorganic crystals, surrounded by plastic scintillator planes for containment tagging. The main characteristics and performance of HEPD-02 are presented, highlighting the architectural choices made to meet the scientific objectives of the mission

Hypertriton Production in p-Pb Collisions at √sNN = 5.02 TeV

The study of nuclei and antinuclei production has proven to be a powerful tool to investigate the formation mechanism of loosely bound states in high-energy hadronic collisions. The first measurement of the production of ${\rm ^{3}_{\Lambda}\rm H}$ in p-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV is presented in this Letter. Its production yield measured in the rapidity interval -1 < y < 0 for the 40% highest multiplicity p-Pb collisions is ${\rm d} N /{\rm d} y =[\mathrm{6.3 \pm 1.8 (stat.) \pm 1.2 (syst.) ] \times 10^{-7}}$. The measurement is compared with the expectations of statistical hadronisation and coalescence models, which describe the nucleosynthesis in hadronic collisions. These two models predict very different yields of the hypertriton in small collision systems such as p-Pb and therefore the measurement of ${\rm d} N /{\rm d} y$ is crucial to distinguish between them. The precision of this measurement leads to the exclusion with a significance larger than 6$\sigma$ of some configurations of the statistical hadronisation, thus constraining the production mechanism of loosely bound states

K0SK0S and K0SK± femtoscopy in pp collisions at √s = 5.02 and 13 TeV

Femtoscopic correlations with the particle pair combinations (KSKS0)-K-0 and (KSK +/-)-K-0 are studied in pp collisions at root s= 5.02 and 13 TeV by the ALICE experiment. At both energies, boson source parameters are extracted for both pair combinations, by fitting models based on Gaussian size distributions of the sources, to the measured two-particle correlation functions. The interaction model used for the (KSKS0)-K-0 analysis includes quantum statistics and strong final-state interactions through the f(0) (980) and a(0) (980) resonances. The model used for the (KSK +/-)-K-0 analysis includes only the final-state interaction through the a(0) resonance. Source parameters extracted in the present work are compared with published values from pp collisions at root s = 7 TeV and the different pair combinations are found to be consistent. From the observation that the strength of the (KSKS0)-K-0 correlations is significantly greater than the strength of the (KSK +/-)-K-0 correlations, the new results are compatible with the a(0) resonance being a tetraquark state of the form (q(1), (q(2)) over bar, s, (s) over bar), where q(1) and q(2) are uor d quarks. (C) 2022 European Organization for Nuclear Research, ALICE. Published by Elsevier B.V

Long- and short-range correlations and their event-scale dependence in high-multiplicity pp collisions at 1as = 13 TeV

Two-particle angular correlations are measured in high-multiplicity proton-proton collisions at s = 13 TeV by the ALICE Collaboration. The yields of particle pairs at short-( 06\u3b7 3c 0) and long-range (1.6 < | 06\u3b7| < 1.8) in pseudorapidity are extracted on the near-side ( 06\u3c6 3c 0). They are reported as a function of transverse momentum (pT) in the range 1 < pT< 4 GeV/c. Furthermore, the event-scale dependence is studied for the first time by requiring the presence of high-pT leading particles or jets for varying pT thresholds. The results demonstrate that the long-range \u201cridge\u201d yield, possibly related to the collective behavior of the system, is present in events with high-pT processes as well. The magnitudes of the short- and long-range yields are found to grow with the event scale. The results are compared to EPOS LHC and PYTHIA 8 calculations, with and without string-shoving interactions. It is found that while both models describe the qualitative trends in the data, calculations from EPOS LHC show a better quantitative agreement for the pT dependency, while overestimating the event-scale dependency. [Figure not available: see fulltext.

First Measurement of Antideuteron Number Fluctuations at Energies Available at the Large Hadron Collider

The first measurement of event-by-event antideuteron number fluctuations in high energy heavy-ion collisions is presented. The measurements are carried out at midrapidity (1?1 < 0.8) as a function of collision centrality in Pb-Pb collisions atv (NN)-N-s= 5.02 TeV using the ALICE detector. A significant negative correlation between the produced antiprotons and antideuterons is observed in all collision centralities. The results are compared with a state-of-the-art coalescence calculation. While it describes the ratio of higher order cumulants of the antideuteron multiplicity distribution, it fails to describe quantitatively the magnitude of the correlation between antiproton and antideuteron production. On the other hand, thermal-statistical model calculations describe all the measured observables within uncertainties only for correlation volumes that are different with respect to those describing proton yields and a similar measurement of net-proton number fluctuations

Measurement of beauty-strange meson production in Pb–Pb collisions at sNN=5.02TeV via non-prompt Ds + mesons

The production yields of non-prompt D_s^+ mesons, namely D_s^+ mesons from beauty-hadron decays, were measured for the first time as a function of the transverse momentum (pT) at midrapidity (|y| phi pi+, with phi -> K+ K-, in the 4 < pT < 36 GeV/c and 2 < pT < 24 GeV/c intervals for the 0–10% and 30–50% centrality classes, respectively. The measured yields of non-prompt D_S^+ mesons are compared to those of prompt D_s^+ and non-prompt D0 mesons by calculating the ratios of the production yields in Pb–Pb collisions and the nuclear modification factor RAA. The ratio between the RAA of non-prompt D_s^+ and prompt D_s^+ mesons, and that between the RAA of non-prompt D_s^+ and non-prompt D0 mesons in central Pb–Pb collisions are found to be on average higher than unity in the 4 < pT < 12 GeV/c interval with a statistical significance of about 1.6 sigma and 1.7 sigma, respectively. The measured RAA ratios are compared with the predictions of theoretical models of heavy-quark transport in a hydrodynamically expanding QGP that incorporate hadronisation via quark recombination