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visit by Her Excellency Dr Katarzyna Lubnauer, Secretary of State, Ministry of National Education, Poland
No full textVisit by Her Excellency Dr Katarzyna Lubnauer, Secretary of State, Ministry of National Education, Republic of Polan
Time-Dependent Modeling of the Sub-Hour Spectral Evolution During the 2013 Outburst of Mrk 421
No full textIn April 2013, the TeV blazar Markarian~421 underwent one of its most powerful emission outbursts to date. An extensive multi-instrument campaign featuring MAGIC, VERITAS, and \textit{NuSTAR} provided comprehensive very-high-energy (VHE; GeV) and X-ray coverage over nine consecutive days. In this work, we perform a detailed spectral analysis of the X-ray and VHE emissions on sub-hour timescales throughout the flare. We identify several clockwise spectral hysteresis loops in the X-rays, revealing a spectral evolution more complex than a simple harder-when-brighter trend. The VHE spectrum extends beyond 10 TeV, and its temporal evolution closely mirrors the behavior in the X-rays. We report the first evidence of VHE spectral hysteresis occurring simultaneously with the X-ray loops. To interpret these findings, we apply a time-dependent leptonic model to 240 broadband spectral energy distributions (SEDs) binned on a 15-minute scale, allowing us to self-consistently track the particle distribution's history. Our modeling shows that the majority of the sub-hour flux and spectral variations are driven by changes in the luminosity and slope of the injected electron distribution. The required variations in the electron slope are difficult to reconcile with magnetic reconnection but are consistent with a shock-acceleration scenario where the shock compression ratio evolves by a factor of . The model also points to a relatively stable magnetic field and emitting region size, favoring a scenario where the emission originates from a stationary feature in the jet, such as a recollimation shock. However, this scenario requires a jet Lorentz factor that significantly exceeds values from VLBI measurements to account for the high minimum electron energy implied by the lack of variability in the optical band
ML-based classification in an open-source framework for the ALICE heavy-flavour analysis
No full textThe ALICE Collaboration aims to precisely measure heavy-flavour (HF) hadron production in high-energy proton-proton and heavy-ion collisions to provide valuable tests of perturbative quantum chromodynamics models and insights into hadronisation mechanisms. Measurements of the production of the Ξ+c and Λ+c baryons decaying into a proton (p) and charged π and K mesons are remarkable examples of investigation in the HF sector. As in other ALICE analyses, a Boosted Decision Tree (BDT) classifiers has been adopted to discriminate the signal yields from the background processes. Especially for the Ξ+c → pK−π+ process, the Machine Learning (ML)-based approach is required and particularly challenging due to its large combinatorial background, small branching ratio, and short O(100 µm) decay length. FAIR, a European project synergic to the ALICE experiment, aims to set up an open-source, user-friendly, and interactive pytorch-based environment external to the official ALICE framework to perform BDT-based multivariate analyses. The FAIR benchmark imports different ML libraries (XGBoost, Sklearn, and Ray) to prepare the data and configure the BDT models in Jupyter notebooks. Currently, the training is performed on a preliminary dataset with limited statistics using a partitioned shared GPU available through an Apache Mesos cluster at the ReCaS-Bari datacenter. In the future, when a larger dataset is available, we intend to leverage a GPU-powered Kubernetes cluster for processing large-scale applications, including ML tool training. This contribution will present a performance comparison of the investigated ML architectures trained with simulated signal events and background data provided by ALICE during LHC Run 3 proton-proton collisions at √s = 13.6 TeV
Design and Construction of the CMS Outer Tracker for the Phase-2 Upgrade
No full textThe High Luminosity LHC (HL-LHC) is expected to deliver an integrated luminosity of 3000-4000~fb after 10 years of operation with peak instantaneous luminosity reaching about 5-7.5cms. During Long Shutdown 3, several components of the CMS detector will undergo major changes, called Phase-2 upgrades, to be able to operate in the challenging environment of the HL-LHC. The current CMS tracker will be replaced. The Phase-2 Outer Tracker (OT) will have high radiation tolerance, higher granularity, and the capability to handle higher data rates. Moreover, the OT will provide tracking information to the Level-1 trigger, for the first time at hadron colliders, allowing trigger rates to be kept at a sustainable level without sacrificing physics potential. For this, the OT will be made of modules with two closely spaced silicon sensors read out by front-end ASICs, which can correlate hits in the two sensors creating short track segments (stubs), used for tracking in the L1 track finder. The modules come in two flavors: strip-strip (2S) and pixel-strip (PS), containing different sensor configurations and multiple ASICs. This contribution will present the design of the Phase-2 OT, the first results with pre-production devices, and the quality assurance procedures used to ensure the functionality of the modules: from fulfilling the precision specification of the module assembly procedure to ensuring the proper communication among the module's ASICs
Measurement of the Upsilon(1S), Upsilon(2S), and Upsilon(3S) differential production cross sections in pp collisions at 13.6 TeV
No full textThe production cross sections of the (1S), (2S), and (3S) mesons are measured in proton-proton collisions at TeV, using a data sample collected in 2022 by the CMS experiment and corresponding to an integrated luminosity of 37.4 . The measurement is performed in the dimuon decay channels, differentially as a function of transverse momentum in the 20200 GeV range, in the and rapidity intervals
Artist Martyna Marciniak during the Collide Copenhagen residency with Arts at CERN
No full textMartyna Marciniak is a Polish, Berlin-based artist and researcher working at the intersection of sculpture, 3D art, animation, and film. Her interdisciplinary multi-media projects harness spatial storytelling, speculative fictions, and 3D reconstruction to interrogate how design and technology mirror and shape ideologies and social biases. After completing her architectural education at the Bartlett School of Architecture in London, her spatial research has intersected with Human Rights Investigations. Collaborating with media outlets like CNN and BBC, as well as NGOs such as Forensic Architecture, Amnesty International, and Human Rights Watch, her work has shed light on critical issues of human rights abuses and structural injustices. In 2022, her co-founded research group, Border Emergency Collective, documented the experiences of migrants at the Polish-Belarusian border. She has exhibited at Ars Electronica, the Warsaw Biennale in Poland, Kinema Icon in Bucharest/Romania, Haus Gropius in Dessau and the deTour Festival in Hong Kong/China, among others. In 2025, Marciniak was selected as the winner of the Collide Copenhagen residency
