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Summary Plot of Lepton Flavour Universality Measurements using Events July 2025
No full textThis note presents a summary plot of the results of three ATLAS analyses which test the universality of the lepton couplings to -bosons using topanti-top events as of July 2025
Measurement of the natC(n,p) and natC(n,d) reactions from n_TOF at CERN
No full textThe energy dependence of the cross section of the (n,p) and (n,d) reactions on natC has been studied for the first time at the n_TOF facility at CERN, from the particle detection threshold up to 25 MeV. The measurement was performed with two telescopes made of position-sensitive silicon ΔE-E detectors, covering the angular range from 20∘ to 140∘. A detector efficiency has been determined by means of Monte Carlo simulations of the experimental setup. Various assumptions on the angular distributions and branching ratios of the excited levels of the residual 11B, 12B, 13B nuclei were considered. In particular, theoretical calculations based on the TALYS-2.0 code were used and the systematic uncertainties in the analysis results were determined from the variations in these distributions. The n_TOF data on the (n,p) and (n,d) reaction on carbon are characterized by a higher accuracy and wider energy range than currently available in literature. A comparison with current evaluations from different libraries reveals a rather significant disagreement with the n_TOF results, while a remarkable agreement is observed with the prediction of TALYS-2.0 for this light element.The energy dependence of the cross section of the (n,p) and (n,d) reactions on C has been studied for the first time at the n_TOF facility at CERN, from the particle detection threshold up to 25 MeV. The measurement was performed with two telescopes made of position-sensitive silicon - detectors, covering the angular range from 20° to 140°. A detector efficiency has been determined by means of Monte Carlo simulations of the experimental setup. Various assumptions on the angular distributions and branching ratios of the excited levels of the residual B, B, B nuclei were considered. In particular, theoretical calculations based on the TALYS-2.0 code were used and the systematic uncertainties in the analysis results were determined from the variations in these distributions. The n_TOF data on the (n,p) and (n,d) reaction on carbon are characterized by a higher accuracy and wider energy range than currently available in literature. A comparison with current evaluations from different libraries reveals a rather significant disagreement with the n_TOF results, while a remarkable agreement is observed with the prediction of TALYS-2.0 for this light element
HIE ISOLDE cryogenics operation results and recent upgrades
No full textThe High Intensity and Energy ISOLDE (HIE-ISOLDE) enables the acceleration of medium to heavy radioactive isotopes at energies reaching 10 MeV per nucleon, a significant increase from the previous configuration limited to 2.8 MeV per nucleon. The journey towards this achievement involved a progressive deployment of radiofrequency cryomodules starting in 2015. In 2018, the final configuration was reached with successful operation of four high-beta radiofrequency cryomodules in series. This paper presents an overview of the operational results over the last 8 years, but especially focuses on the recent enhancements made in 2023 to the cryogenics system and tested during the last physics run. A comprehensive overhaul of the cryomodule operation process was implemented to minimize restart times following unexpected interruptions, to facilitate operators handling and to harden the process control structure. Hardware modifications have also been implemented to improve equipment availability and were successfully commissioned
Study of the UHV compatibility of selected ferritic stainless steels for application in vacuum systems of future gravitational wave detectors
No full textFuture gravitational wave detectors (GWDs), such as the Cosmic Explorer and the Einstein Telescope, demand extensive ultrahigh vacuum (UHV) systems, making material cost and performance critical considerations. This study explores the potential of ferritic stainless steel, specifically AISI 441 and AISI 444, as a cost-effective alternative to the commonly used austenitic stainless steel for UHV components, focusing on the analysis of outgassing rates pre- and postbakeout at 80 and 150°C for 48 h. With hydrogen contents up to 50 times lower than those measured in standard AISI 304L steel, the tested grades showed, after bakeout, hydrogen outgassing rates down to 10−15 mbar l s−1cm−2. The measured values are three orders of magnitude lower than those of similarly conditioned austenitic stainless steels. These results highlight ferritic stainless steel as a promising, economical, and high-performance candidate for future GWDs vacuum systems
3rd Italian Workshop on the Physics at High Intensity (WIFAI2024)
No full textThe workshop aims to gather together the various Italian research communities involved in the study of Particle Physics at High Intensity. The workshop is an opportunity to discuss the present and future of this research sector, favouring the discussion and the exchange of ideas and synergies between experiments and also with the theoretical community. Favouring the participation of the young members of the High-Intensity community, is also one of the aims of the workshop, dedicating to them a Young Scientist Forum session, for which abstracts will be accepted. The workshop will develop along the lines of the Scientific Programme summarised below, giving space to the three pillars of our work: theory, physics measurements and detector R&D. Scientific Programme: CKM and CP violation Spectroscopy Lepton Flavour Rare Decays Dark Sector Young Scientist Foru
ATLAS Outreach and Education
No full textThe ATLAS Experiment on the Large Hadron Collider at CERN is one of the largest most complex scientific instruments ever constructed. It has been built and operated by an international collaboration of over 5900 members of 103 nationalities from 243 institutes around the world. While the scientific goals and results of the experiment are continually reported to colleagues in the field through conferences, journals and seminars, the collaboration makes a dedicated effort to engage other key audiences with the excitement of its achievements. These audiences range from young children and students, members of the media, politicians and scientists in the same or different fields. Efforts include effective sustained online communication, development of educational material, including Masterclasses and open data programmes, creation of exhibitions and events at festivals, hosting of local and virtual visits to the experiment, and much more. The work is led by members of the collaboration, supported by a dedicated Outreach team including expertise in education and communication. We report on recent developments and plans, as well as the challenges faced by the current fragmented media landscape
Top-quark pair production in heavy-ion collisions in the ATLAS experiment
No full textMeasurements of top-quark pairs in heavy-ion collisions are expected to provide novel probes of nuclear parton distribution functions as well as to bring unique information about the time evolution of strongly interacting matter. We report the observation of top-quark pair production in proton-lead collisions at the centre-of-mass energy of 8.16 TeV in the ATLAS experiment at the LHC. Top-quark pair production is studied in the lepton+jets and the dilepton channels, and the nuclear modification factor is measured for the first time for the top-quark pair process. Also, the first observation of top-quark production in Pb+Pb collisions at the centre-of-mass energy of 5.02 TeV is presented. Top-quark pair production is measured in the channel, with a significance of 5.0 standard deviations. The result is compared to theory predictions based on different nuclear PDF sets
Second HL-LHC Cold Powering System validated
No full textThe second Cold Powering System for the HL-LHC was assembled and qualified at CERN in June 2025. Tests and measurements in SM18 demonstrated stable and reproducible performance, and confirmed the electrical robustness of the design. 8 of these systems will be in the HL-LHC in total (2 each side of both ATLAS and CMS interaction points), and each features a cryogenic distribution box called DFH which will be in the new HiLumi galleries and a cryogenic distribution box in the LHC tunnel, connected via a Superconducting Link
