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Student Sessions 2025
No full textPlease enter your presentation and a short description of your projec
Student Sessions 2025
No full textHello, My name is Samadhi Nirmani Yasodara, and I have completed a Bachelor of Science (Honours) degree in Physics from the University of Ruhuna, Sri Lanka.
As a participant in the CERN Summer Student Programme, I worked on a project focused on the Small-strip Thin Gap Chambers (sTGC) of the ATLAS detector, in collaboration with the ATLAS group. My study focused on developing monitoring plots and analyzing historical data to identify and understand the causes of high-voltage instabilities in the sTGC chambers, contributing to improved diagnostics and long-term detector reliability
The CERN n_TOF NEAR station for astrophysics- and application-related neutron activation measurements
No full textA new experimental area, the NEAR station, has recently been built at the CERN n_TOF facility, at a short distance from the spallation target (3 m). The new area, characterized by a neutron beam of very high flux, has been designed with the purpose of performing activation measurements of interest for astrophysics and various applications. The beam is transported from the spallation target to the NEAR station through a hole in the shielding wall of the target, inside which a collimator is inserted. The new area is complemented with a -ray spectroscopy laboratory, the GEAR station, equipped with a high-efficiency HPGe detector, for the measurement of the activity resulting from irradiation of a sample in the NEAR station. The use of a moderator/filter assembly is envisaged, in order to produce a neutron beam with quasi-Maxwellian energy distribution, of different thermal energies, necessary for the determination of Maxwellian Averaged Cross Sections of astrophysical interest. A new fast-cycling activation technique is also being investigated for measurements of reactions leading to isotopes of very short half life.A new experimental area, the NEAR station, has recently been built at the CERN n TOF facility, at a short distance from the spallation target (1.5 m). The new area, characterized by a neutron beam of very high flux, has been designed with the purpose of performing activation measurements of interest for astrophysics and various applications. The beam is transported from the spallation target to the NEAR station through a hole in the shielding wall of the target, inside which a collimator is inserted. The new area is complemented with a γ-ray spectroscopy laboratory, the GEAR station, equipped with a high efficiency HPGe detector, for the measurement of the activity resulting from irradiation of a sample in the NEAR station. The use of a moderator/filter assembly is envisaged, in order to produce a neutron beam of Maxwellian shape at different thermal energies, necessary for the measurement of Maxwellian Averaged Cross Sections of astrophysical interest. A new fast-cycling activation technique is also being investigated, for measurements of reactions leading to isotopes of very short half life
Recent results from NA61/SHINE
No full textThe NA61/SHINE experiment at the CERN SPS is a multipurpose fixed-target spectrometer for charged and neutral hadron measurements. Its research program includes studies of strong interactions as well as reference measurements for neutrino and cosmic-ray physics. A significant advantage of NA61/SHINE over collider experiments is its extended coverage of phase space available for hadron production. This includes the nearly entire forward hemisphere for charged hadrons and additionally, a large part of the backward hemisphere for specific neutrals. This paper summarizes a selected set of new results, obtained by NA61/SHINE since the last SQM conference (Busan, 2022). Particular attention is devoted to (1) the first-ever direct measurement of open charm production in nucleus-nucleus collisions at SPS energies (2) the difference observed between charged and neutral meson production in Ar+Sc reactions, up to now not understood by existing models, and (3) the importance of baseline effects in the search for the critical point of strongly interacting matter.The NA61/SHINE experiment at the CERN SPS is a multipurpose fixed-target spectrometer for charged and neutral hadron measurements. Its research program includes studies of strong interactions as well as reference measurements for neutrino and cosmic-ray physics. A significant advantage of NA61/SHINE over collider experiments is its extended coverage of phase space available for hadron production. This includes the nearly entire forward hemisphere for charged hadrons and additionally, a large part of the backward hemisphere for specific neutrals. This paper summarizes a selected set of new results, obtained by NA61/SHINE since the last SQM conference (Busan, 2022). Particular attention is devoted to (1) the first-ever direct measurement of open charm production in nucleus-nucleus collisions at SPS energies (2) the difference observed between charged and neutral meson production in Ar+Sc reactions, up to now not understood by existing models, and (3) the importance of baseline effects in the search for the critical point of strongly interacting matter
Particle production and identification for the T10 secondary beamline of the CERN East Area
No full textThe particle composition of the T10 beam line in the renovated East Hall at CERN was measured using several methods: pressure scans on a threshold Cherenkov counter, a lead-glass calorimeter, time-of-flight, and finally using two separate threshold Cherenkov counters. For the pressure scans, at a given beam momentum, the count rate in the Cherenkov counters is measured as a function of pressure which allows computation of the fraction of a specific particle species. For the method using two threshold Cherenkov counters, one set above and one set below the threshold for the particle species to be identified, the difference relative to a beam trigger gives the relevant fraction. The measurement was proposed in the “Beamline For Schools” competition by team Particular Perspective and carried out in 2023. This data was expanded with pressure scans in 2023 and 2025. A comprehensive overview results of the particle content of the T10 beam.The particle composition of the T10 beam line in the renovated East Hall at CERN has been measured using several experimental techniques and detectors: pressure scans on a threshold Cherenkov counter, a lead-glass calorimeter, time-of-flight, and finally using two separate threshold Cherenkov counters. For the pressure scans, at a given beam momentum, the count rate in the Cherenkov counters is measured as a function of pressure in the counter. The count rate normalized to the rate of beam particles allows computation of the fraction of a specific particle type in the beam. For the method using two threshold Cherenkov counters, one set above and one set below the threshold for the particle species to be identified, with the difference relative to a beam trigger giving the particle fraction for that species. The measurement was proposed in the context of the ``Beamline For Schools'' competition by team Particular Perspective and carried out in 2023. This data was expanded with pressure scans in 2023 and 2025. Overlapping data is compared, leading to a comprehensive overview of the particle content of the T10 beam
ATLAS Event Display: Higgs boson decay to two muons
No full textCandidate Higgs boson event decaying to two muons, recorded by ATLAS in 2024 at 13.6 TeV
Search for associated production of a Higgs boson and of two vector bosons via vector boson scattering
No full textA search for the production of a Higgs boson in association with two vector bosons via vector boson scattering is presented. The search uses CMS data from proton-proton collisions at collected from 2016 to 2018, corresponding to an integrated luminosity of . Selected events are consistent with the presence of two jets originating from vector boson scattering and a Higgs boson decaying into a pair of b quarks, reconstructed as a single large-cone jet, while final states with 0, 1 or 2 charged leptons coming from the decays of the two vector bosons are studied. The study constrains the quartic coupling strength relative to the standard model, , in the observed (expected) range [0.40, 1.60] ([0.34, 1.66]) at confidence level when the other Higgs boson couplings are fixed to their SM values. The process is also sensitive to the and quartic couplings independently, whose strengths relative to the standard model are constrained in the observed (expected) ranges [0.17, 1.84] ([0.11, 1.89]) and [--0.37, 2.38] ([--0.54, 2.54]), for and respectively. A two-dimensional scan is performed to determine exclusion regions in the - plane