The Experts below are selected from a list of 947133 Experts worldwide ranked by ideXlab platform
Tim Ameel - One of the best experts on this subject based on the ideXlab platform.
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microtube gas flows with second order slip flow and temperature jump boundary conditions
International Journal of Thermal Sciences, 2009Co-Authors: Nian Xiao, John Elsnab, Tim AmeelAbstract:Abstract Second-order slip flow and temperature jump boundary conditions are applied to solve the momentum and energy equations in a microtube for an isoflux thermal boundary condition. The flow is assumed to be hydrodynamically fully developed, and the thermal field is either fully developed or developing from the tube entrance. In general, second-order boundary conditions assuming an effective mean free path Model Predict a lower slip velocity than a first-order Model assuming a hard sphere mean free path Model. Heat transfer effects associated with rarefied flow are reduced for the second-order Model. The effect of the second-order terms is most significant at the upper limit of the slip regime. For airflow at standard conditions, the maximum second-order change to the Nusselt number is on the order of 15%. The second-order effect is also more significant in the entrance region of the tube. Nusselt numbers are found to increase relative to their no-slip values when temperature jump effects are small. In cases where slip and temperature jump effects are of the same order, or where temperature jump effects dominate, the Nusselt number decreases when compared to traditional no-slip conditions.
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microtube gas flows with second order slip flow and temperature jump boundary conditions
ASME 4th International Conference on Nanochannels Microchannels and Minichannels Parts A and B, 2006Co-Authors: Nian Xiao, John Elsnab, Tim AmeelAbstract:Second-order slip flow and temperature jump boundary conditions are applied to solve the momentum and energy equations in a microtube for an isoflux thermal boundary condition. The flow is assumed to be hydrodynamically fully developed, and the thermal field is either fully developed or developing from the tube entrance. In general, second-order boundary conditions assuming an effective mean free path Model Predict a lower slip velocity than a first-order Model assuming a hard sphere mean free path Model. Heat transfer effects associated with rarefied flow are reduced for the second-order Model. The effect of the second-order terms is most significant at the upper limit of the slip regime. For airflow at standard conditions, the maximum second-order change to the Nusselt number is on the order of 15%. The second-order effect is also more significant in the entrance region of the tube. Nusselt numbers are found to increase relative to their no-slip values when temperature jump effects are small. In cases where slip and temperature jump effects are of the same order, or where temperature jump effects dominate, the Nusselt number decreases when compared to traditional no-slip conditions. © 2008 Elsevier Masson SAS. All rights reserved.
G Aad - One of the best experts on this subject based on the ideXlab platform.
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search for light long lived neutral particles produced in pp collisions at s 13tev and decaying into collimated leptons or light hadrons with the atlas detector
European Physical Journal C, 2020Co-Authors: G Aad, S Webb, T Dreyer, K Jakobs, M Spousta, M Cobal, Peilong Wang, Yufeng Wang, Stefan SchmittAbstract:Several Models of physics beyond the Standard Model Predict the existence of dark photons, light neutral particles decaying into collimated leptons or light hadrons. This paper presents a search for long-lived dark photons produced from the decay of a Higgs boson or a heavy scalar boson and decaying into displaced collimated Standard Model fermions. The search uses data corresponding to an integrated luminosity of 36.1 fb$^{-1}$ collected in proton–proton collisions at $\sqrt{s} = 13$ $\text {Te}\text {V}$ recorded in 2015–2016 with the ATLAS detector at the Large Hadron Collider. The observed number of events is consistent with the expected background, and limits on the production cross section times branching fraction as a function of the proper decay length of the dark photon are reported. A cross section times branching fraction above 4 pb is excluded for a Higgs boson decaying into two dark photons for dark-photon decay lengths between 1.5 mm and 307 mm.
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search for metastable heavy charged particles with large ionisation energy loss in pp collisions at s 8 tev using the atlas experiment
European Physical Journal C, 2015Co-Authors: G Aad, B. Abbott, M. Abolins, Ovsat Abdinov, J Abdallah, R Aben, H Abramowicz, O S Abouzeid, H Abreu, R AbreuAbstract:Many extensions of the Standard Model Predict the existence of charged heavy long-lived particles, such as R-hadrons or charginos. These particles, if produced at the Large Hadron Collider, should bemoving non-relativistically and are therefore identifiable through the measurement of an anomalously large specific energy loss in the ATLAS pixel detector. Measuring heavy long-lived particles through their track parameters in the vicinity of the interaction vertex provides sensitivity to metastable particles with lifetimes from 0.6 ns to 30 ns. A search for such particles with the ATLAS detector at the Large Hadron Collider is presented, based on a data sample corresponding to an integrated luminosity of 18.4 fb(-1) of pp collisions at root s = 8 TeV. No significant deviation from the Standard Model background expectation is observed, and lifetime-dependent upper limits on R-hadrons and chargino production are set. Gluino R-hadrons with 10 ns lifetime and masses up to 1185 GeV are excluded at 95 % confidence level, and so are charginos with 15 ns lifetime and masses up to 482 GeV.
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search for long lived neutral particles decaying into lepton jets in proton proton collisions at s 8 tev with the atlas detector
Journal of High Energy Physics, 2014Co-Authors: G Aad, B. Abi, B. Abbott, M. Abolins, Ovsat Abdinov, J Abdallah, R Aben, Samah Abdel Khalek, Hass Abouzeid, H AbramowiczAbstract:Several Models of physics beyond the Standard Model Predict neutral particles that decay into final states consisting of collimated jets of light leptons and hadrons (so-called "lepton jets"). These particles can also be long-lived with decay length comparable to, or even larger than, the LHC detectors' linear dimensions. This paper presents the results of a search for lepton jets in proton-proton collisions at the centre-of-mass energy of root s = 8 TeV in a sample of 20.3 fb(-1) collected during 2012 with the ATLAS detector at the LHC. Limits on Models Predicting Higgs boson decays to neutral long-lived lepton jets are derived as a function of the particle's proper decay length.
Nian Xiao - One of the best experts on this subject based on the ideXlab platform.
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microtube gas flows with second order slip flow and temperature jump boundary conditions
International Journal of Thermal Sciences, 2009Co-Authors: Nian Xiao, John Elsnab, Tim AmeelAbstract:Abstract Second-order slip flow and temperature jump boundary conditions are applied to solve the momentum and energy equations in a microtube for an isoflux thermal boundary condition. The flow is assumed to be hydrodynamically fully developed, and the thermal field is either fully developed or developing from the tube entrance. In general, second-order boundary conditions assuming an effective mean free path Model Predict a lower slip velocity than a first-order Model assuming a hard sphere mean free path Model. Heat transfer effects associated with rarefied flow are reduced for the second-order Model. The effect of the second-order terms is most significant at the upper limit of the slip regime. For airflow at standard conditions, the maximum second-order change to the Nusselt number is on the order of 15%. The second-order effect is also more significant in the entrance region of the tube. Nusselt numbers are found to increase relative to their no-slip values when temperature jump effects are small. In cases where slip and temperature jump effects are of the same order, or where temperature jump effects dominate, the Nusselt number decreases when compared to traditional no-slip conditions.
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microtube gas flows with second order slip flow and temperature jump boundary conditions
ASME 4th International Conference on Nanochannels Microchannels and Minichannels Parts A and B, 2006Co-Authors: Nian Xiao, John Elsnab, Tim AmeelAbstract:Second-order slip flow and temperature jump boundary conditions are applied to solve the momentum and energy equations in a microtube for an isoflux thermal boundary condition. The flow is assumed to be hydrodynamically fully developed, and the thermal field is either fully developed or developing from the tube entrance. In general, second-order boundary conditions assuming an effective mean free path Model Predict a lower slip velocity than a first-order Model assuming a hard sphere mean free path Model. Heat transfer effects associated with rarefied flow are reduced for the second-order Model. The effect of the second-order terms is most significant at the upper limit of the slip regime. For airflow at standard conditions, the maximum second-order change to the Nusselt number is on the order of 15%. The second-order effect is also more significant in the entrance region of the tube. Nusselt numbers are found to increase relative to their no-slip values when temperature jump effects are small. In cases where slip and temperature jump effects are of the same order, or where temperature jump effects dominate, the Nusselt number decreases when compared to traditional no-slip conditions. © 2008 Elsevier Masson SAS. All rights reserved.
V O De Haan - One of the best experts on this subject based on the ideXlab platform.
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search for exotic spin dependent couplings of the neutron with matter using spin echo based neutron interferometry
Physical Review D, 2020Co-Authors: Steven R Parnell, W M Snow, A A Van Well, J Plomp, R M Dalgliesh, Ninajuliane Steinke, Joshaniel F K Cooper, Niels Geerits, K E Steffen, V O De HaanAbstract:Various theories beyond the Standard Model Predict new particles with masses in the sub-eV range with very weak couplings to ordinary matter which can possess spin-dependent couplings to electrons and nucleons. We report null results of a search for possible exotic spin-dependent couplings of the neutron which could be induced by the exchange of light weakly coupled bosons or spin-gravity coupling conducted using a spin-echo neutron spectrometer. We constrain the products ${g}_{A}^{2}$ and ${g}_{A}{g}_{V}$ of the axial vector coupling of the neutron to the matter of the Earth through the exchange of a weakly coupled vector boson for force ranges between the metre scale and the radius of the Earth. We also constrain the constants in some theories of exotic spin-gravity couplings.
Stefan Schmitt - One of the best experts on this subject based on the ideXlab platform.
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search for light long lived neutral particles produced in pp collisions at sqrt s 13 tev and decaying into collimated leptons or light hadrons with the atlas detector
European Physical Journal C, 2020Co-Authors: S Webb, T Dreyer, K Jakobs, M Spousta, M Cobal, Peilong Wang, Stefan Schmitt, Yufeng Wang, Jaroslava SchovancováAbstract:Several Models of physics beyond the Standard Model Predict the existence of dark photons, light neutral particles decaying into collimated leptons or light hadrons. This paper presents a search for long-lived dark photons produced from the decay of a Higgs boson or a heavy scalar boson and decaying into displaced collimated Standard Model fermions. The search uses data corresponding to an integrated luminosity of 36.1 fb$^{-1}$ collected in proton-proton collisions at $\sqrt{s} =$ 13 TeV recorded in 2015-2016 with the ATLAS detector at the Large Hadron Collider. The observed number of events is consistent with the expected background, and limits on the production cross section times branching fraction as a function of the proper decay length of the dark photon are reported. A cross section times branching fraction above 4 pb is excluded for a Higgs boson decaying into two dark photons for dark-photon decay lengths between 1.5 mm and 307 mm.
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search for light long lived neutral particles produced in pp collisions at s 13tev and decaying into collimated leptons or light hadrons with the atlas detector
European Physical Journal C, 2020Co-Authors: G Aad, S Webb, T Dreyer, K Jakobs, M Spousta, M Cobal, Peilong Wang, Yufeng Wang, Stefan SchmittAbstract:Several Models of physics beyond the Standard Model Predict the existence of dark photons, light neutral particles decaying into collimated leptons or light hadrons. This paper presents a search for long-lived dark photons produced from the decay of a Higgs boson or a heavy scalar boson and decaying into displaced collimated Standard Model fermions. The search uses data corresponding to an integrated luminosity of 36.1 fb$^{-1}$ collected in proton–proton collisions at $\sqrt{s} = 13$ $\text {Te}\text {V}$ recorded in 2015–2016 with the ATLAS detector at the Large Hadron Collider. The observed number of events is consistent with the expected background, and limits on the production cross section times branching fraction as a function of the proper decay length of the dark photon are reported. A cross section times branching fraction above 4 pb is excluded for a Higgs boson decaying into two dark photons for dark-photon decay lengths between 1.5 mm and 307 mm.