Kísérleti adatminőség meghatározása az LHC CMS kísérletében gépi tanulási módszerrel

A CERN nemzetközi kutatóközpont CMS kísérlete a Nagy Hadronütközetőnek, a világ legnagyobb energiájú részecskegyorsítójának, proton-proton ütközéseiben vizsgálja az elemi részecskék tulajdonságait és keres nyomokat egy a részecskefizika Standard Modelljén túlmutató elméletre. A komplex CMS detektor modern félvezető technológiát alkalmazó alrendszerei fontos szerepet játszanak az események rekonstrukciójába

Computational Study of Catalytic Urethane Formation

Polyurethanes (PUs) are widely used in different applications, and thus various synthetic procedures including one or more catalysts are applied to prepare them. For PU foams, the most important catalysts are nitrogen-containing compounds. Therefore, in this work, the catalytic effect of eight different nitrogen-containing catalysts on urethane formation will be examined. The reactions of phenyl isocyanate (PhNCO) and methanol without and in the presence of catalysts have been studied and discussed using the G3MP2BHandHLYP composite method. The solvent effects have also been considered by applying the SMD implicit solvent model. A general urethane formation mechanism has been proposed without and in the presence of the studied catalysts. The proton affinities (PA) were also examined. The barrier height of the reaction significantly decreased (∆E0 > 100 kJ/mol) in the presence of the studied catalysts, which proves the important effect they have on urethane formation. The achieved results can be applied in catalyst design and development in the near future

The Pixel Luminosity Telescope: a detector for luminosity measurement at CMS using silicon pixel sensors

International audienceThe Pixel Luminosity Telescope is a silicon pixel detector dedicated to luminosity measurement at the CMS experiment at the LHC. It is located approximately 1.75 m from the interaction point and arranged into 16 “telescopes”, with eight telescopes installed around the beam pipe at either end of the detector and each telescope composed of three individual silicon sensor planes. The per-bunch instantaneous luminosity is measured by counting events where all three planes in the telescope register a hit, using a special readout at the full LHC bunch-crossing rate of 40 MHz. The full pixel information is read out at a lower rate and can be used to determine calibrations, corrections, and systematic uncertainties for the online and offline measurements. This paper details the commissioning, operational history, and performance of the detector during Run 2 (2015–18) of the LHC, as well as preparations for Run 3, which will begin in 2022