3,464 research outputs found
Calibration strategy of CMS electromagnetic calorimeter
No full textCalibration is one of the main factors that set limits on the ultimate performance of the CMS electromagnetic calorimeter at LHC. Crystals raw intercalibration from lab measurements during assembly and CERN-SPS test beam of Supermodules will represent the precalibration at the start-up. In situ calibration with physics events will be the main tool to reduce the constant term to the design goal of 0.5%. The calibration strategy will be described in detail
Extracting the speed of sound in quark–gluon plasma with ultrarelativistic lead–lead collisions at the LHC
No full textUltrarelativistic nuclear collisions create a strongly interacting state of hot and dense quark-gluon matter that exhibits a remarkable collective flow behavior with minimal viscous dissipation. To gain deeper insights into its intrinsic nature and fundamental degrees of freedom, we determine the speed of sound in an extended volume of quark-gluon plasma using lead-lead (PbPb) collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 0.607 nb-1. The measurement is performed by studying the multiplicity dependence of the average transverse momentum of charged particles emitted in head-on PbPb collisions. Our findings reveal that the speed of sound in this matter is nearly half the speed of light, with a squared value of0.241±0.002(stat)±0.016(syst)in natural units. The effective medium temperature, estimated using the mean transverse momentum, is219±8(syst)MeV. The measured squared speed of sound at this temperature aligns precisely with predictions from lattice quantum chromodynamic (QCD) calculations. This result provides a stringent constraint on the equation of state of the created medium and direct evidence for a deconfined QCD phase being attained in relativistic nuclear collisions
Calibration of the CMS Electromagnetic Calorimeter
No full textCalibration is one of the factors that set limits on the ultimate performance of the CMS electromagnetic calorimeter (ECAL) at LHC. In situ calibration with physics events will be the main tool to reduce the constant term in the energy dependent resolution function to the design goal of 0.5 %. At the start of detector operation, a fast intercalibration method, based on phi symmetry in minimum bias events, will be used, exploiting the uniformity of energy deposition as a function of phi at a given eta. Energetic electrons from Z -> e^+e^- decays will be recorded at a sufficiently high rate, even at the initial low luminosity, to provide an intercalibration of calorimeter regions and to set the absolute energy scale. Once the Tracker has been commissioned, intercalibration of different crystals within a single module may be achieved using E/p measurement of isolated electrons. This cal ibration strategy will be described in detail and illustrated with simulated results
Improvement on PbWO4 Crystal Intercalibration Precision from Light Yield Measurements at the INFN-ENEA Regional Center
No full textPendin
Design options for the upgrade of the CMS electromagnetic calorimeter
No full textAbstractThe CMS scintillating lead-tungstate calorimeter was designed to operate for at least ten years at the LHC, assuming an instantaneous luminosity of 1034 cm−2 s−1. The measurements obtained with data collected in LHC Run1 (2010–2012) show that the detector has performed according to design specifications and will survive with excellent performance through the lifetime of the LHC. However, plans for an upgrade of the LHC (the High Luminosity LHC, HL-LHC, project) aim at accumulating a much higher integrated luminosity, up to 3000 fb−1 in ten years. This will expose the detector to a total irradiation about six times higher with respect to the design specifications.An intense campaign of activities has started to define the improvements needed to survive such an increase in irradiation levels. The activities carried out include irradiation studies, simulations, design, realisation and test of prototypes of new detectors that may substitute the present one in the endcap regions.The options currently under study and the results obtained so far on the subjects outlined above will be presented
MR-based artificial intelligence model to assess response to therapy in locally advanced rectal cancer
No full textPurpose: To develop and validate an Artificial Intelligence (AI) model based on texture analysis of high-resolution T2 weighted MR images able 1) to predict pathologic Complete Response (CR) and 2) to identify non-responders (NR) among patients with locally-advanced rectal cancer (LARC) after receiving neoadjuvant chemoradiotherapy (CRT). Method: Fifty-five consecutive patients with LARC were retrospectively enrolled in this study. Patients underwent 3 T Magnetic Resonance Imaging (MRI) acquiring T2-weighted images before, during and after CRT. All patients underwent complete surgical resection and histopathology was the gold standard. Textural features were automatically extracted using an open-source software. A sub-set of statistically significant textural features was selected and two AI models were built by training a Random Forest (RF) classifier on 28 patients (training cohort). Model performances were estimated on 27 patients (validation cohort) using a ROC curve and a decision curve analysis. Results: Sixteen of 55 patients achieved CR. The AI model for CR classification showed good discrimination power with mean area under the receiver operating curve (AUC) of 0.86 (95% CI: 0.70, 0.94) in the validation cohort. The discriminatory power for the NR classification showed a mean AUC of 0.83 (95% CI: 0.71,0.92). Decision curve analysis confirmed higher net patient benefit when using AI models compared to standard-of-care. Conclusions: AI models based on textural features of MR images of patients with LARC may help to identify patients who will show CR at the end of treatment and those who will not respond to therapy (NR) at an early stage of the treatment
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