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Technology Computer-Aided Design (TCAD) allows us to use computers in order to develop semiconductor processing technologies and devices and optimize them. Within a framework of a study of silicon photomultipliers (SiPM) a simulation of these devices has been made. The simulation was performed for the irradiated SiPMs and current-voltage characteristics were obtained for the modeled devices. Investigation of current-voltage curve below breakdown with regard to the simulated structure was performed. Obtained curves are presented.

Synopsys TCAD is a professional software for the development of the semiconductor technological process and device simulaion. In order to study a radiation damage of the surface of silicon photomultipliers (SiPMs) the simulation of these devices using Synopsys TCAD has been made. Experimental samples were produced by KETEK GmbH and have been irradiated with the different doses of X-rays with an energy of E≈12 keV. The current-voltage characteristics below breakdown measured before and after irradiations have been simulated with TCAD. Obtained curves for experimental and simulation data are presented.

The hadron endcap (HE) calorimeter is one of the major sections of CMS detector, used for measurement of the hadrons energy. Phase1 upgrade of the front-end electronics components in the HE calorimeter is being prepared, in particular to improve ability to handle increased pile-up and mitigate radiation damage of optical system in the high eta region. Tests of Phase1 HE Front-end system including new photo-sensors, silicon photomultipliers (SiPM), as well as new charge integrator encoder (QIE11) were performed in the Burn-in station in b904 at CERN. In this note, analysis and measurement results for the new generation front-end electronics components are presented.

A data sample of events from proton–proton collisions with two isolated same-sign leptons, missing transverse momentum, and jets is studied in a search for signatures of new physics phenomena by the CMS Collaboration at the LHC. The data correspond to an integrated luminosity of 35.9 fb - 1 , and a center-of-mass energy of 13 TeV . The properties of the events are consistent with expectations from standard model processes, and no excess yield is observed. Exclusion limits at 95% confidence level are set on cross sections for the pair production of gluinos, squarks, and same-sign top quarks, as well as top-quark associated production of a heavy scalar or pseudoscalar boson decaying to top quarks, and on the standard model production of events with four top quarks. The observed lower mass limits are as high as 1500 GeV for gluinos, 830 GeV for bottom squarks. The excluded mass range for heavy (pseudo)scalar bosons is 350–360 (350–410) GeV . Additionally, model-independent limits in several topological regions are provided, allowing for further interpretations of the results.

A bstract A measurement of the groomed jet mass in PbPb and pp collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV with the CMS detector at the LHC is presented. Jet grooming is a recursive procedure which sequentially removes soft constituents of a jet until a pair of hard subjets is found. The resulting groomed jets can be used to study modifications to the parton shower evolution in the presence of the hot and dense medium created in heavy ion collisions. Predictions of groomed jet properties from the pythia and herwig ++ event generators agree with the measurements in pp collisions. When comparing the results from the most central PbPb collisions to pp data, a hint of an increase of jets with large jet mass is observed, which could originate from additional medium-induced radiation at a large angle from the jet axis. However, no modification of the groomed mass of the core of the jet is observed for all PbPb centrality classes. The PbPb results are also compared to predictions from the jewel and q - pythia event generators, which predict a large modification of the groomed mass not observed in the data.

A search is presented for additional neutral Higgs bosons in the $\\tau\\tau$ final state in proton-proton collisions at the LHC. The search is performed in the context of the minimal supersymmetric extension of the standard model (MSSM), using the data collected with the CMS detector in 2016 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. To enhance the sensitivity to neutral MSSM Higgs bosons, the search includes production of the Higgs boson in association with b quarks. No significant deviation above the expected background is observed. Model-independent limits at 95% confidence level (CL) are set on the product of the branching fraction for the decay into $\\tau$ leptons and the cross section for the production via gluon fusion or in association with b quarks. These limits range from 18 pb at 90 GeV to 3.5 fb at 3.2 TeV for gluon fusion and from 15 pb (at 90 GeV) to 2.5 fb (at 3.2 TeV) for production in association with b quarks. In the m$_{\\text{h}}^{\\text{mod+}}$ scenario these limits translate into a 95% CL exclusion of $\\tan\\beta>$ 6 for neutral Higgs boson masses below 250 GeV, where $\\tan\\beta$ is the ratio of the vacuum expectation values of the neutral components of the two Higgs doublets. As a result the 95% CL exclusion contour reaches 1.6 TeV for $\\tan\\beta=$ 60.

A bstract A search is presented for the decay of the 125 GeV Higgs boson (H) to a pair of new light pseudoscalar bosons (a), followed by the prompt decay of each a boson to a bottom quark-antiquark pair, H → aa → b b ¯ b b ¯ . The analysis is performed using a data sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb − 1 . To reduce the background from standard model processes, the search requires the Higgs boson to be produced in association with a leptonically decaying W or Z boson. The analysis probes the production of new light bosons in a 15 < m a < 60 GeV mass range. Assuming the standard model predictions for the Higgs boson production cross sections for pp → WH and ZH, model independent upper limits at 95% confidence level are derived for the branching fraction B H → aa → b b ¯ b b ¯ . The combined WH and ZH observed upper limit on the branching fraction ranges from 1.10 for m a = 20 GeV to 0.36 for m a = 60 GeV, complementing other measurements in the μμττ , ττττ and bb ℓℓ ( ℓ = μ , τ ) channels.

A bstract A measurement is performed of Higgs bosons produced with high transverse momentum ( p T ) via vector boson or gluon fusion in proton-proton collisions. The result is based on a data set with a center-of-mass energy of 13 TeV collected in 2016–2018 with the CMS detector at the LHC and corresponds to an integrated luminosity of 138 fb − 1 . The decay of a high- p T Higgs boson to a boosted bottom quark-antiquark pair is selected using large-radius jets and employing jet substructure and heavy-flavor taggers based on machine learning techniques. Independent regions targeting the vector boson and gluon fusion mechanisms are defined based on the topology of two quark-initiated jets with large pseudorapidity separation. The signal strengths for both processes are extracted simultaneously by performing a maximum likelihood fit to data in the large-radius jet mass distribution. The observed signal strengths relative to the standard model expectation are 4.9 − 1.6 + 1.9 and 1.6 − 1.5 + 1.7 for the vector boson and gluon fusion mechanisms, respectively. A differential cross section measurement is also reported in the simplified template cross section framework.

The recovery time of the Hamamatsu SiPM linear assembly was measured. The assembly contains eight SiPMs of 2.8mm active area diameter; pixel size is 15xl5mkm2. The assembly is used for Phase1 upgrade in hadron calorimeter of the CMS experiment. Recovering process is found to depend on the number of the pixels fired and varied from 7 ±1 ns to 23 ± 3 ns for 50 Ohm readout impedance.

A search for new phenomena is performed using events with jets and significant transverse momentum imbalance, as inferred through the M T 2 variable. The results are based on a sample of proton–proton collisions collected in 2016 at a center-of-mass energy of 13 TeV with the CMS detector and corresponding to an integrated luminosity of 35.9 fb -1 . No excess event yield is observed above the predicted standard model background, and the results are interpreted as exclusion limits at 95% confidence level on the masses of predicted particles in a variety of simplified models of R -parity conserving supersymmetry. Depending on the details of the model, 95% confidence level lower limits on the gluino (light-flavor squark) masses are placed up to 2025 (1550) GeV . Mass limits as high as 1070 (1175) GeV are set on the masses of top (bottom) squarks. Information is provided to enable re-interpretation of these results, including model-independent limits on the number of non-standard model events for a set of simplified, inclusive search regions.