Time of Arrival calibration of HGCAL prototype modules using charge injection

As of January 2019 the Large Hadron Collider (LHC) has entered its second long shutdown (LS2) and is under maintenance. During Run 2 the collision centre-of-mass energy was 13 TeV with an instantaneous lumi-nosity of ∼ 1 · 1034 cm−2 s−1. This corresponds to an average of 40 simultaneous inelastic interactions per 25 ns-spaced bunch crossing, and these interactions are referred to as ‘pileup’. After the next long shutdown (LS3), the High Lumi-nosity LHC (HL-LHC) will start, increasing the instan-taneous luminosity of about 5 times. This increase of instantaneous luminosity is a challenge for detector radiation tolerance and for the mitigation of the extreme pileup where up to 200 collisions per bunch crossing are expected. For the detectors at the centre of which the collision happen, this increase requires material that can both be resistant to radiation and deliver precise measurements. To cope with these conditions the CMS collaboration [1] is in the middle of an extensive R&D programme to upgrade many parts of the detec-tor, including the replacement of its calorimeter endcaps. One of the key parameters for the new endcap calorimeter is a good timing resolution for the pileup mitigation and tracking efficiency. The CMS collaboration chose a High Granularity Calorimeter (HG-CAL) endcaps to cope with these conditions [2]. At this moment the HGCAL is in the final research and designing phase, the first prototypes of silicon modules have been assembled and tested, but further upgrades will be incorporated. Module performance, including timing resolution, has been tested with beams at CERN, DESY and Fermilab, the results have been summarised in [3]

An Experimental Study of Electromagnetically Induced Liquid Metal Flow for Aluminium Transport and Degassing in a Linear Channel

Šobrīd alumīnija degazācija tiek veikta, izmantojot ātri rotējošus keramikas uzgaļus, kas kausējumā ievada mazus inertas gāzes burbuļus. Metodes galvenā problēma ir uzgaļu erozija un nepieciešamība tos bieži mainīt. Tādēļ šajā darbā tiek analizēta jauna, elektromagnētiska, bezkontakta metode šķidrā metāla plūsmas ierosināšanai. Plūsmu taisnstūrveida, lineārā kanālā ierosina ar rotējošu pastāvīgo magnētu dipolu, kas novietots tuvu kanāla sienai. Veikti kārtas novērtējumi, izveidota eksperimentālā iekārta modeļa verifikācijai un veikta tehnoloģijas mērogošana, kas apstiprina, ka tehnoloģija ir perspektīva gan alumīnija degazācijai, gan transportam.Currently aluminium degassing is carried out using rapidly rotating ceramic nozzles that inject small bubbles of inert gas into the melt. The main problem with this method is the erosion of the nozzles and the need to change them frequently. Therefore, this research analyzes a new, electromagnetic, non-contact method for initiating the flow of liquid metal. The flow in the rectangular, linear channel is initiated by a rotating permanent magnet dipole placed close to the channel wall. Order of magnitude evaluations have been performed, an experimental device for model verification has been developed and technology scaling has been done, which confirms that the technology is promising for both aluminum degassing and transport

An Experimental Study Of Electromagnetically Excited Liquid Metal Surface Waves

Darbā eksperimentāli tiek pētīta virsmas viļņu elektromagnētiska ierosināšana šķidrā metālā (GaInSn eitektikā), izmantojot Bitera spoli, kas rada mainīgu magnētisko lauku. Tiek pētīts, kā mainīgā magnētiskā lauka stiprums ietekmē veidojošos virsmas viļņus, kā šie viļņi izmainās, ja klāt mainīgajam laukam pievieno spēcīgu, pastāvīgu magnētisko lauku, kura virziens sakrīt ar mainīgā magnētiskā lauka virzienu. Lai raksturotu iegūtos virsmas viļņus, ar dažādām metodēm noteikts to viļņu garums, frekvence, amplitūda, kā arī plūsma metāla tilpumā. Eksperimentālie rezultāti demonstrē iespēju šķidrā metālā ierosināt virsmas viļņus, izmantojot bezkontakta – elektromagnētisku pieeju.A contactless, electromagnetic approach is investigated for the excitation of the surface waves for electrically conductive materials, more precisely for GaInSn alloy. Surface waves are generated by an alternating magnetic field using a Bitter coil, additionally, scaling possibility is investigated by an externally applied permanent magnetic field. Cases are compared both quantitatively and qualitatively by analysing photos acquired and using other measurement techniques to characterize the waves achieved. Experiments demonstrate the possibility of exciting intense surface waves electromagnetically and show the potential to scale technology to industrial size for increased free surface applications

Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s\sqrt{s} = 5.02 TeV

International audienceThe inclusive jet cross section is measured as a function of jet transverse momentum $p_\mathrm{T}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s}$ = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb$^{-1}$. The jets are reconstructed with the anti-$k_\mathrm{T}$ algorithm using a distance parameter of $R$ = 0.4, within the rapidity interval $\lvert y\rvert$$\lt$ 2, and across the kinematic range 0.06 $\lt$$p_\mathrm{T}$$\lt$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$

Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s\sqrt{s} = 5.02 TeV

International audienceThe inclusive jet cross section is measured as a function of jet transverse momentum $p_\mathrm{T}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s}$ = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb$^{-1}$. The jets are reconstructed with the anti-$k_\mathrm{T}$ algorithm using a distance parameter of $R$ = 0.4, within the rapidity interval $\lvert y\rvert$$\lt$ 2, and across the kinematic range 0.06 $\lt$$p_\mathrm{T}$$\lt$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$

Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s= \sqrt{s} = 5.02 TeV

The inclusive jet cross section is measured as a function of jet transverse momentum $p_{\mathrm{T}}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s} =$ 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4$\,\text{pb}^{-1}$. The jets are reconstructed with the anti-$k_{\mathrm{T}}$ algorithm using a distance parameter of $R=$ 0.4, within the rapidity interval $|y| <$ 2, and across the kinematic range 0.06 $< p_{\mathrm{T}} <$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$.The inclusive jet cross section is measured as a function of jet transverse momentum $p_\mathrm{T}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s}$ = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb$^{-1}$. The jets are reconstructed with the anti-$k_\mathrm{T}$ algorithm using a distance parameter of $R$ = 0.4, within the rapidity interval $\lvert y\rvert$$\lt$ 2, and across the kinematic range 0.06 $\lt$$p_\mathrm{T}$$\lt$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$

Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s\sqrt{s} = 5.02 TeV

International audienceThe inclusive jet cross section is measured as a function of jet transverse momentum $p_\mathrm{T}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s}$ = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb$^{-1}$. The jets are reconstructed with the anti-$k_\mathrm{T}$ algorithm using a distance parameter of $R$ = 0.4, within the rapidity interval $\lvert y\rvert$$\lt$ 2, and across the kinematic range 0.06 $\lt$$p_\mathrm{T}$$\lt$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$

Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s\sqrt{s} = 5.02 TeV

International audienceThe inclusive jet cross section is measured as a function of jet transverse momentum $p_\mathrm{T}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s}$ = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb$^{-1}$. The jets are reconstructed with the anti-$k_\mathrm{T}$ algorithm using a distance parameter of $R$ = 0.4, within the rapidity interval $\lvert y\rvert$$\lt$ 2, and across the kinematic range 0.06 $\lt$$p_\mathrm{T}$$\lt$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$

Search for stealth supersymmetry in final states with two photons, jets, and low missing transverse momentum in proton-proton collisions at s\sqrt{s} = 13 TeV

International audienceThe results of a search for stealth supersymmetry in final states with two photons and jets, targeting a phase space region with low missing transverse momentum ($p_\text{T}^\text{miss}$), are reported. The study is based on a sample of proton-proton collisions at $\sqrt{s}$ =13 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 138 fb$^{-1}$. As LHC results continue to constrain the parameter space of the minimal supersymmetric standard model, the low $p_\text{T}^\text{miss}$ regime is increasingly valuable to explore. To estimate the backgrounds due to standard model processes in such events, we apply corrections derived from simulation to an estimate based on a control selection in data. The results are interpreted in the context of simplified stealth supersymmetry models with gluino and squark pair production. The observed data are consistent with the standard model predictions, and gluino (squark) masses of up to 2150 (1850) GeV are excluded at the 95% confidence level

Search for nonresonant Higgs boson pair production in final state with two bottom quarks and two tau leptons in proton-proton collisions at <math altimg="si1.svg"><msqrt><mrow><mi>s</mi></mrow></msqrt><mo linebreak="goodbreak" linebreakstyle="after">=</mo><mn>13</mn><mtext> TeV</mtext></math>

International audienceA search for the nonresonant production of Higgs boson pairs (HH ) via gluon-gluon and vector boson fusion processes in final states with two bottom quarks and two tau leptons is presented. The search uses data from proton-proton collisions at a center-of-mass energy of s=13TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 138fb−1. Events in which at least one tau lepton decays hadronically are considered and multiple machine learning techniques are used to identify and extract the signal. The data are found to be consistent, within uncertainties, with the standard model (SM) predictions. Upper limits on the HH production cross section are set to constrain the parameter space for anomalous Higgs boson couplings. The observed (expected) upper limit at 95% confidence level corresponds to 3.3 (5.2) times the SM prediction for the inclusive HH cross section and to 124 (154) times the SM prediction for the vector boson fusion HH cross section. At 95% confidence level, the Higgs field self-coupling is constrained to be within −1.7 and 8.7 times the SM expectation, and the coupling of two Higgs bosons to two vector bosons is constrained to be within −0.4 and 2.6 times the SM expectation