The direct search for dark matter in the form of weakly interacting massive particles (WIMP) is performed by detecting nuclear recoils produced in a target material from the WIMP elastic scattering. The experimental identification of the direction of the WIMP-induced nuclear recoils is a crucial asset in this field, as it enables unmistakable modulation signatures for dark matter. The Recoil Directionality (ReD) experiment was designed to probe for such directional sensitivity in argon dual-phase time projection chambers (TPC), that are widely considered for current and future direct dark matter searches. The TPC of ReD was irradiated with neutrons at the INFN Laboratori Nazionali del Sud. Data were taken with nuclear recoils of known directions and kinetic energy of 72 keV, which is within the range of interest for WIMP-induced signals in argon. The direction-dependent liquid argon charge recombination model by Cataudella et al. was adopted and a likelihood statistical analysis was performed, which gave no indications of significant dependence of the detector response to the recoil direction. The aspect ratio
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Abstract R of the initial ionization cloud is$$R < 1.072$$ -
Free, publicly-accessible full text available September 1, 2025
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The ALICE Collaboration reports measurements of the semi-inclusive distribution of charged-particle jets recoiling from a high transverse momentum (high) charged hadron, inand central Pb-Pb collisions at center-of-mass energy per nucleon–nucleon collisionTeV. The large uncorrelated background in central Pb-Pb collisions is corrected using a data-driven statistical approach which enables precise measurement of recoil jet distributions over a broad range inand jet resolution parameter. Recoil jet yields are reported for, 0.4, and 0.5 in the rangeand, whereis the azimuthal angular separation between hadron trigger and recoil jet. The low-reach of the measurement explores unique phase space for studying jet quenching, the interaction of jets with the quark–gluon plasma generated in high-energy nuclear collisions. Comparison ofdistributions fromand central Pb-Pb collisions probes medium-induced jet energy loss and intra-jet broadening, while comparison of their acoplanarity distributions explores in-medium jet scattering and medium response. The measurements are compared to theoretical calculations incorporating jet quenching.
©2024 CERN, for the ALICE Collaboration 2024 CERN Free, publicly-accessible full text available July 1, 2025 -
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The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum (high) hadron trigger in proton-proton and central Pb-Pb collisions at. A data-driven statistical method is used to mitigate the large uncorrelated background in central Pb-Pb collisions. Recoil jet distributions are reported for jet resolution parameter, 0.4, and 0.5 in the rangeand trigger-recoil jet azimuthal separation. The measurements exhibit a marked medium-induced jet yield enhancement at lowand at large azimuthal deviation from. The enhancement is characterized by its dependence on, which has a slope that differs from zero by. Comparisons to model calculations incorporating different formulations of jet quenching are reported. These comparisons indicate that the observed yield enhancement arises from the response of the QGP medium to jet propagation.
© 2024 CERN, for the ALICE Collaboration 2024 CERN Free, publicly-accessible full text available July 1, 2025 -
Free, publicly-accessible full text available June 1, 2025
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Abstract The Aria cryogenic distillation plant, located in Sardinia, Italy, is a key component of the DarkSide-20k experimental program for WIMP dark matter searches at the INFN Laboratori Nazionali del Gran Sasso, Italy. Aria is designed to purify the argon, extracted from underground wells in Colorado, USA, and used as the DarkSide-20k target material, to detector-grade quality. In this paper, we report the first measurement of argon isotopic separation by distillation with the 26 m tall Aria prototype. We discuss the measurement of the operating parameters of the column and the observation of the simultaneous separation of the three stable argon isotopes: $${}^{36}\hbox {Ar}$$ 36 Ar , $${}^{38}\textrm{Ar}$$ 38 Ar , and $${}^{40}\textrm{Ar}$$ 40 Ar . We also provide a detailed comparison of the experimental results with commercial process simulation software. This measurement of isotopic separation of argon is a significant achievement for the project, building on the success of the initial demonstration of isotopic separation of nitrogen using the same equipment in 2019.more » « less
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Measurements of the-dependent flow vector fluctuations in Pb–Pb collisions atusing azimuthal correlations with the ALICE experiment at the Large Hadron Collider are presented. A four-particle correlation approach [ALICE Collaboration, ] is used to quantify the effects of flow angle and magnitude fluctuations separately. This paper extends previous studies to additional centrality intervals and provides measurements of the-dependent flow vector fluctuations atwith two-particle correlations. Significant-dependent fluctuations of theflow vector in Pb–Pb collisions are found across different centrality ranges, with the largest fluctuations of up tobeing present in the 5% most central collisions. In parallel, no evidence of significant-dependent fluctuations oforis found. Additionally, evidence of flow angle and magnitude fluctuations is observed with more thansignificance in central collisions. These observations incollisions indicate where the classical picture of hydrodynamic modeling with a common symmetry plane breaks down. This has implications for hard probes at high, which might be biased by-dependent flow angle fluctuations of at least 23% in central collisions. Given the presented results, existing theoretical models should be reexamined to improve our understanding of initial conditions, quark–gluon plasma properties, and the dynamic evolution of the created system.
©2024 CERN, for the ALICE Collaboration 2024 CERN Free, publicly-accessible full text available June 1, 2025 -
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A<sc>bstract</sc> Results on the transverse spherocity dependence of light-flavor particle production (
π , K, p,ϕ , K*0,$$ {\textrm{K}}_{\textrm{S}}^0 $$ $$ \sqrt{s} $$ $$ \left({S}_{\textrm{O}}^{p_{\textrm{T}}=1}\right) $$ $$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$ $$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$ η | < 0.8) estimator is used.The production rates of strange particles are found to be slightly higher for soft isotropic topologies, and severely suppressed in hard jet-like topologies. These effects are more pronounced for hadrons with larger mass and strangeness content, and observed when the topological selection is done within a narrow multiplicity interval. This demonstrates that an important aspect of the universal scaling of strangeness enhancement with final-state multiplicity is that high-multiplicity collisions are dominated by soft, isotropic processes. On the contrary, strangeness production in events with jet-like processes is significantly reduced.
The results presented in this article are compared with several QCD-inspired Monte Carlo event generators. Models that incorporate a two-component phenomenology, either through mechanisms accounting for string density, or thermal production, are able to describe the observed strangeness enhancement as a function of
$$ {S}_{\textrm{O}}^{p_{\textrm{T}}=1} $$ Free, publicly-accessible full text available May 1, 2025
