Some aspects of thermal resistance measurement technique for IMPATT and light-emitting diodes

Some aspects of measuring the thermal resistance to a constant heat flow at a p-n junction–package region in IMPATT and light-emitting diodes are considered. We propose a method of studying the thermal resistance of high-power light-emitting diodes. This method makes it possible to increase accuracy of measuring the thermal resistance by determining the temperature at a linear section of the voltage−temperature curve. A possibility to measure the thermal resistance of IMPATT diodes by using the pulse I-V curves is shown. This enables one to simplify calculations and increase accuracy of measuring the thermal resistance

Studies of the Response of the Prototype CMS Hadron Calorimeter, Including Magnetic Field Effects, to Pion, Electron, and Muon Beams

We report on the response of a prototype CMS hadron calorimeter module to charged particle beams of pions, muons, and electrons with momenta up to 375 GeV/c. The data were taken at the H2 and H4 beamlines at CERN in 1995 and 1996. The prototype sampling calorimeter used copper absorber plates and scintillator tiles with wavelength shifting fibers for readout. The effects of a magnetic field of up to 3 Tesla on the response of the calorimeter to muons, electrons, and pions are presented, and the effects of an upstream lead tungstate crystal electromagnetic calorimeter on the linearity and energy resolution of the combined calorimetric system to hadrons are evaluated. The results are compared with Monte Carlo simulations and are used to optimize the choice of total absorber depth, sampling frequency, and longitudinal readout segmentation.Comment: 89 pages, 41 figures, to be published in NIM, corresponding author: P de Barbaro, [email protected]

Search for jet extinction in the inclusive jet-pT spectrum from proton-proton collisions at s=8 TeV

Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7  fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale

Searches for electroweak neutralino and chargino production in channels with Higgs, Z, and W bosons in pp collisions at 8 TeV

Searches for supersymmetry (SUSY) are presented based on the electroweak pair production of neutralinos and charginos, leading to decay channels with Higgs, Z, and W bosons and undetected lightest SUSY particles (LSPs). The data sample corresponds to an integrated luminosity of about 19.5 fb(-1) of proton-proton collisions at a center-of-mass energy of 8 TeV collected in 2012 with the CMS detector at the LHC. The main emphasis is neutralino pair production in which each neutralino decays either to a Higgs boson (h) and an LSP or to a Z boson and an LSP, leading to hh, hZ, and ZZ states with missing transverse energy (E-T(miss)). A second aspect is chargino-neutralino pair production, leading to hW states with E-T(miss). The decays of a Higgs boson to a bottom-quark pair, to a photon pair, and to final states with leptons are considered in conjunction with hadronic and leptonic decay modes of the Z and W bosons. No evidence is found for supersymmetric particles, and 95% confidence level upper limits are evaluated for the respective pair production cross sections and for neutralino and chargino mass values

On Kozlov-Nikishin Model

Abstract: In framework of Kozlov-Nikishin relativity model there are investigated the scattering problem on Columb potential and wave functions of discret spectrum for particular in the conic cylinder. The paper has scientific-methodic character. It may be used as supplement to lectures on the theory of special functions.Note: Research direction:Mathematical problems and theory of numerical method

On asymptotic regimes for the multiple Meixner polynomials

Abstract: The asymptotic behavior of the multiple orthogonal polynomials for two Meixner measures of different exponential decay is investigated. The results are represented in terms of the equilibrium problems of the logarithmic potential theory and in terms of the meromorphic functions on Riemann surfaces.Note: Research direction:Mathematical problems and theory of numerical method

On Algorithm of Fast Calculation of the Number π4.

Abstract: By using Hermite-Pade approximates for the system of Markov functions are consisted a cyclic graph there are found rational approximations of the number π4are satisfying three-term recurrence relations.Note: Research direction:Mathematical problems and theory of numerical method

Weak asymptotics of multiple Pollaczek polynomials

Abstract: The polynomials defined by a special two-diagonal non-symmetric operator are considered. The weak asymptotics of the scaled polynomials is obtained. The potential theory interpretation is given.Note: Research direction:Mathematical problems and theory of numerical method