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Multimode Dielectric Resonator for Accurate Determination of Frequency and Temperature Dependence of Complex Permittivity in Small, High-Permittivity Cylinders
No full textWe present a technique to measure permittivity and loss tangent in high-permittivity cylinders. This method utilizes a resonator to conduct concurrent measurements at the three lowest quasi-TE01p modes across various temperatures, combined with an algorithm to fit the loss tangent dependence on frequency and temperature. Our technique serves as a preliminary step to characterize dielectrics used in Hakki–Coleman resonators for surface resistance measurements. Consequently, parameters for dielectric characterization—such as sample size and modes used—are determined by the requirements of subsequent surface resistance measurements, rather than optimizing the determination of the material’s intrinsic dielectric properties. Despite this focus, our measurements on rutile align well with existing literature. We conducted measurements on three rutile samples from the same production batch, covering a frequency range from 6.0 to 9.4 GHz, with uncertainties of less than 0.7% for permittivity and 13% for loss tangent. These measurements revealed sample-to-sample differences that cannot be attributed to measurement uncertainty alone. Our findings suggest that the previous approach of using multiple rutile crystals with varying sizes to assess the frequency dependence of dielectric loss may lead to significant uncertainty in predicting loss tangents due to variations in sample properties. We describe the possible extension of this technique to characterize other dielectrics beyond rutile, including commercial dielectrics, across frequency and temperature. We also discuss its potential widespread application in the use of Hakki–Coleman resonators for quality control of materials used in particle accelerators, such as the future circular collider hadron-hadron (FCC-h)
First results from the SND@LHC experiment
No full textSND@LHC started taking data at the beginning of Run 3 of the LHC. The experiment is designedto perform measurements with neutrinos produced in proton-proton collisions at the LHC in anenergy range between 100 GeV and 1 TeV. It covers a previously unexplored pseudo-rapidity rangeof 7.2 < η < 8.4. The detector is located 480 m downstream of the ATLAS interaction point inthe TI18 tunnel. The detector is composed of a hybrid system based on an 800 kg target massof tungsten plates, interleaved with emulsion and electronic trackers, followed downstream by acalorimeter and a muon system. The configuration allows efficiently distinguishing between allthree neutrino flavours, opening a unique opportunity to probe physics of heavy flavour productionat the LHC in the region that is not accessible to ATLAS, CMS and LHCb. This region isof particular interest also for future circular colliders and for predictions of very high-energyatmospheric neutrinos. The detector concept is also well suited to searching for Feebly InteractingParticles via signatures of scattering in the detector target. The experiment has published severalresults. This work focuses on the experience gained from the first measurements and how this isbeing used to achieve the physics goals of SND@LHC
Neutrinos at the LHC - Results from FASER
No full textThe goal of FASER, the ForwArd Search ExpeRiment, at the CERN LHC, is to investigate light, weakly-interacting particles. Aligned with the collision axis line-of-sight of the ATLAS interaction point, it is located 480 m downstream, and covers the previously unexplored pseudorapidity range of > 8.8. Sitting in front of the main electronic detector, the passive FASER neutrino detector focuses on high-energy collider neutrino interactions in the TeV regime, extending current cross-section measurements. The FASER collaboration announced in August 2023 the first direct observation of electron neutrino interactions in a particle collider experiment, using only a sub-volume of data collected so far with the FASER detector. Made up of alternating emulsion films and tungsten plates, it has a target mass of 1.1 tonnes. Sub-micron position resolution is achieved, allowing for all three neutrino flavours to be distinguished by their vertex topology in charged current interactions. FASER plans to run throughout the LHC Run 3, collecting 250 fb^−1 of data. By probing forward hadron production and deep inelastic scattering of high-energy neutrinos, FASER results will provide important insights in QCD. In this presentation, recent FASER results, as well as the status of data taking and analysis, will be presented
Latest results for searches of exotic decays with NA62 in beam-dump mode
No full textThe NA62 experiment at CERN took data in 2016–2018 with the main goal of measuring the decay. In this talk we report on the search for visible decays of exotic mediators from data taken in "beam-dump" mode with the NA62 experiment. NA62 can be run as a "beam-dump" experiment by removing the kaon production target and moving the upstream collimators into a "closed" position. In this configuration 400~GeV protons are dumped on an absorber and New Physics (NP) particles, including dark photons, dark scalars and axion-like particles, may be produced and reach a decay volume beginning 80~m downstream of the absorber. More than protons on target have been collected in "beam-dump" mode by NA62 in 2021. Recent results from analysis of this data, with a particular emphasis on Dark Photon and Axion-like particle Models, are presented. We also report new results on the first NA62 search for long-lived NP particles decaying in flight to hadronic final states based on a blind analysis of a sample of protons on dump collected in 2021
HL-LHC prospects for the measurement of triple-Higgs production in the 6b final state at the ATLAS experiment
No full textProjection studies of the ATLAS Run 2 search for non-resonant triple Higgs production in the final state are presented to highlight the expected performance achievable at the High Luminosity LHC. Sensitivities are projected assuming a center-of-mass energy of 14 TeV for a variety of integrated luminosities ranging from 1000 to 3000 fb. Results are presented in terms of upper limits on the signal strength, as well as simultaneous constraints on the Higgs self-coupling modifiers. Constraints on the quartic Higgs self-coupling modifier , directly accessible via production at the LHC, are also presented when fixing the Higgs trilinear coupling modifier to the SM. Various scenarios of reduced systematic uncertainties are also considered, which highlight the impact of improvements in experimental modeling and theoretical predictions. Furthermore, the impact of improved -tagging algorithms on the analysis in the final state is studied. With (without) systematic uncertainties, the expected 95% CL exclusion limit on is set to 109 (99) times the SM prediction, while the 95% confidence interval for assuming is [-84, 96] ([-79, 90]), for a total integrated luminosity of 3000~fb. Simultaneous constraints on the Higgs self-coupling modifiers are reported in all extrapolation scenarios, showing that the HL-LHC dataset will allow the exclusion of an increasingly significant portion of the parameter phase space within the perturbative unitarity bounds
Visit by Princess Maha Chakri Sirindhorn, Kingdom of Thailand
No full textVisit by Her Royal Highness Princess Maha Chakri Sirindhorn, Kingdom of Thailan
Supplemental material: Measurement of isolated prompt photon production in pp and p-Pb collisions at the LHC
No full textThis note provides supplementary material for the paper ``Measurement of isolated prompt photon production in pp and p-Pb collisions''. In particular, figures related to the measurement in pp collisions at TeV are presented, which has been performed using a purity estimation with the template fitting technique. We demonstrate that the measurement is consistent with previously published results in the same collision system using a purity estimation with the ABCD method. This additional study using the template fit for purity estimation allows canceling systematic uncertainties in the nuclear modification factor , which uses p-Pb data with purities obtained using the template fitting approach
Measurement of meson production in pp and p-Pb collisions at = 5.02 TeV
No full textWe present the measurement of the -differential production cross section of mesons in pp and p-Pb collisions at = 5.02 TeV at midrapidity by ALICE. In addition, the first measurement of the nuclear modification factor for mesons at LHC energies is presented, complementing the existing measurements of lighter neutral mesons such as the and . Within the measured -range, the of mesons shows no cold nuclear matter effects within the uncertainties, consistent with previous measurements at lower energies. The ratio is presented for both collision systems, showing no collision system dependence within the uncertainties. The comparison to previously published ratios at lower and higher collision energies in pp collisions suggests a decreasing trend of the ratio above GeV/ with increasing collision energy. The data in both collision systems are compared to predictions from PYTHIA 8, EPOS LHC and DPMJET event generators, revealing significant shortcomings in these models' ability to describe the production of mesons.We present the measurement of the -differential production cross section of mesons in pp and p-Pb collisions at TeV at midrapidity by ALICE. In addition, the first measurement of the nuclear modification factor for mesons at LHC energies is presented, complementing the existing measurements of lighter neutral mesons such as the and . Within the measured -range, the of mesons shows no cold nuclear matter effects within the uncertainties, consistent with previous measurements at lower energies. The ratio is presented for both collision systems, showing no collision system dependence within the uncertainties. The comparison to previously published ratios at lower and higher collision energies in pp collisions suggests a decreasing trend of the ratio above GeV/ with increasing collision energy. The data in both collision systems are compared to predictions from PYTHIA 8, EPOS LHC and DPMJET event generators, revealing significant shortcomings in these models' ability to describe the production of mesons
HL-LHC cryomodule installation into SPS
No full textAfter a successful testing campaign of the RFD pre-series cryomodule in SM18 the cryomodule has been transported in the SPS and installed on the BA6 test stand for additional tests with SPS beam. December 2024 - February 2025