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Observation of the distribution of nuclear magnetization in a molecule
No full textPrecise experimental control and interrogation of molecules and calculations of their structure are enriching the investigation of nuclear and particle physics phenomena. Molecules containing heavy, octupole-deformed nuclei, such as radium, are of particular interest. Here, we report precision laser spectroscopy measurements and theoretical calculations of the structure of the radioactive radium monofluoride molecule 225Ra19F. Our results reveal fine details of the short-range electron-nucleus interaction, indicating the high sensitivity of this molecule to the distribution of magnetization, within the radium nucleus. These results provide a stringent test of the description of the electronic wave function inside the nuclear volume, highlighting the suitability of these molecules for investigating subatomic phenomena.Rapid progress in the experimental control and interrogation of molecules, combined with developments in precise calculations of their structure, are enabling new opportunities in the investigation of nuclear and particle physics phenomena. Molecules containing heavy, octupole-deformed nuclei such as radium are of particular interest for such studies, offering an enhanced sensitivity to the properties of fundamental particles and interactions. Here, we report precision laser spectroscopy measurements and theoretical calculations of the structure of the radioactive radium monofluoride molecule, RaF. Our results allow fine details of the short-range electron-nucleus interaction to be revealed, indicating the high sensitivity of this molecule to the distribution of magnetization, currently a poorly constrained nuclear property, within the radium nucleus. These results provide a direct and stringent test of the description of the electronic wavefunction inside the nuclear volume, highlighting the suitability of these molecules to investigate subatomic phenomena
First oxygen-oxygen collisions recorded by the ATLAS Experiment
No full textCollision events recorded by the ATLAS experiment on 5 July 2025, when stable beams of oxygen, colliding at a centre-of-mass energy per nucleon pair of 5.36 TeV, were delivered to ATLAS by the LHC
Output rates and bandwidth of the High-Level Trigger during early 2025 proton-proton runs
No full textThis note presents selected results on the output rates and bandwidth of the CMS High-Level Trigger (HLT) during the early 2025 proton-proton (pp) run at sqrt(s) = 13.6 TeV
Visit of His Excellency Mr Mehmet Fatih Kacır, Minister of Industry and Technology, Republic of Türkiye
No full textVisit of His Excellency Mr Mehmet Fatih Kacır, Minister of Industry and Technology, Republic of Türkiy
Search for the Higgs boson decay to a boson and a photon in collisions at TeV and TeV with the ATLAS detector
No full textA search for the Higgs boson decay to a boson and a photon in the () final state is performed using collisions recorded with the ATLAS detector at TeV during 2022--2024, corresponding to an integrated luminosity of 165 fb. The signal yield, normalized to the Standard Model prediction, is measured to be , compared to an expected value of . This corresponds to an observed (expected) signal significance of 1.4 (1.5) standard deviations with respect to the background-only hypothesis. The search is combined with those of a similar search performed with 139 fb of TeV collisions to provide the most stringent expected sensitivity to date to this rare decay. This results in an observed (expected) signal strength of (), corresponding to an observed (expected) significance of 2.5 (1.9) standard deviations. The measurement is consistent with the Standard Model expectation
Parametrisation and dictionary for CP violating Higgs boson interactions
No full textSearches for charge-parity (CP) violating interactions of the Standard Model (SM) Higgs boson are a key priority of the LHC physics program. Experimental results from ATLAS and CMS are often reinterpreted within a variety of theoretical parametrisations, the most commonly used being the Higgs basis, 's and angles, CP fractions and effective field theories (EFT) such as the SMEFT and the Higgs EFT. However, differing conventions and assumptions across the literature make the translation between these parametrisations nontrivial and prone to inconsistencies. In this paper, we provide a unified framework and construct explicit dictionaries connecting these different approaches. This facilitates a transparent comparison between theoretical studies and experimental analyses, enabling more robust interpretations of CP-violating effects in Higgs interactions
Plasma treated metals after H irradiation and its effect on vacuum breakdown behaviour
No full textVacuum breakdown in accelerator structures is a critical challenge that occurs under high electric fields. In environments subjected to hydrogen ion irradiation or high beam losses, such as in radio-frequency quadrupoles, residual hydrocarbons from the vacuum may result in carbon contamination of the metal surfaces from charged particle induced cracking. Under these conditions, it has been assessed that surface carbon contamination leads to a decrement of the surface electric field holding properties. This study extends the latest research by exploring the efficacy of oxygen plasma cleaning (OPC) on metal electrodes irradiated by low-energy hydrogen ion beam with the purpose of reducing surface carbon contamination. OPC treatment has been employed on different metals, namely, copper beryllium (CuBe2), oxygen-free copper (Cu-OFE), and stainless steel (SS316LN). Treated electrodes have been tested for electric field performance in a dc pulsed system and results compared with nonirradiated electrodes and irradiated ones without OPC treatment. The study indicates a significant reduction in carbon contamination by OPC, enough to allow irradiated materials to achieve performances comparable with the electric field strength of raw surfaces. Moreover, it has been observed that stainless steel samples had some alteration on the surface chemistry that enhanced the material’s ability to sustain high electric fields while decreasing vacuum arcing events. Notably, OPC treated SS316LN electrodes surpassed the performance value of untreated ones, demonstrating the potential of plasma treatments in extending the operational performance of accelerator components.Vacuum breakdown in accelerator structures is a critical challenge that occurs under high electric fields. In environments subjected to hydrogen ion irradiation or high beam losses, such as in Radio-Frequency Quadrupoles (RFQ), residual hydrocarbons from the vacuum may result in carbon contamination of the metal surfaces from charged particle induced cracking. Under these conditions, it has been assessed that surface carbon contamination leads to a decrement of the surface electric field holding properties. This study extends the latest research by exploring the efficacy of Oxygen Plasma Cleaning (OPC) on metal electrodes irradiated by low energy hydrogen ion beam with the purpose of reducing surface carbon contamination. OPC treatment has been employed on different metals, namely copper beryllium (CuBe2), oxygen-free copper (Cu-OFE), and stainless steel (SS316LN). Treated electrodes have been tested for electric field performance in a DC pulsed system and results compared with non-irradiated electrodes and irradiated ones without OPC treatment. The study indicates a significant reduction in carbon contamination by OPC, enough to allow irradiated materials to achieve performances comparable with the electric field strength of raw surfaces. Moreover, it has been observed that stainless steel samples had some alteration in the surface chemistry that enhanced the materials ability to sustain high electric fields while decreasing vacuum arcing events. Notably, OPC treated SS316LN electrodes surpassed the performance value of untreated ones, demonstrating the potential of plasma treatments in extending the operational performance of accelerator components
An electron-hadron collider at the high-luminosity LHC
No full textWe discuss a concept of a lower-energy version of the Large Hadron-electron Collider (LHeC), delivering electron-hadron collisions concurrently to the hadron-hadron collisions at the high-luminosity LHC at CERN. Assuming the use of a 20 GeV electron Energy Recovery Linac (ERL), we report the results on the optimised beam dynamics, accelerator technologies, and detector constraints required for such a "phase-one" LHeC. Finally, we also discuss the ERL configurations and the possibility of delivering electron-hadron collisions during the planned {Run5} of the LHC, which opens excellent research capabilities - the unique scientific potential of the proposed facility is outlined