4,739 research outputs found
Heavy ion physics at CMS and ATLAS: hard probes
Hard probes are indispensable tools to study the hot and dense quark-gluon
matter created in ultra-relativistic heavy ion collisions. These probes are
created in the collision itself with a small cross section, and they serve as
indicators of various properties of the medium, such as temperature, viscosity,
energy density, transport coefficients. Hard probes measured by the CMS and
ATLAS experiments at the LHC include highly energetic jets and charged
particles, quarkonium states, and electroweak gauge bosons. An overview of
those recent experimental results will be given that represent the path towards
high-precision measurements, even in the challenging, high-multiplicity
environment created by colliding heavy ions.Comment: 4 pages, 3 figures, contribution to the 2019 QCD session of the 54th
Rencontres de Morion
Inclusive distributions of charged hadrons in pp collisions at sqrt(s) = 0.9 and 2.36 TeV
Measurements of inclusive charged-hadron transverse-momentum (pT) and
pseudorapidity (eta) distributions are presented for proton-proton collisions
at sqrt(s)=0.9 and 2.36 TeV. For non-single-diffractive interactions, the
average pT of charged hadrons is measured to be 0.46+-0.01(stat.)+-0.01(syst.)
GeV/c at 0.9 TeV and 0.50+-0.01(stat.)+-0.01(syst.) GeV/c at 2.36 TeV, for
|eta|<2.4. At these energies, the measured pseudorapidity densities in the
central region, dNch/deta(|eta|<0.5), are 3.48+-0.02(stat.)+-0.13(syst.) and
4.47+-0.04(stat.)+-0.16(syst.), respectively. The results at 2.36 TeV represent
the highest-energy measurements ever published at a particle collider at the
time of the presentation at the Lake Louise Winter Institute.Comment: 4 pages, 2 figures (2 panels each). Presented at the Lake Louise
Winter Institute 2010; added acknowledgmen
Antiparticle to particle ratios and identified hadron spectra in Cu+Cu and Au+Au collisions
New results on antiparticle to particle ratios in Cu+Cu and Au+Au collisions
at sqrt(s_NN) = 62.4 and 200 GeV from the PHOBOS experiment at RHIC are
presented. Transverse momentum spectra of pions, kaons, protons and antiprotons
from Au+Au collisions at sqrt(s_NN) = 62.4 GeV close to mid-rapidity are also
discussed. Antiparticle to particle ratios are found to be remarkably
independent of the collision centrality in both colliding systems. The
collision energy dependence of the pbar/p ratios is very significant in Cu+Cu
collisions. Baryons are found to have substantially harder transverse momentum
spectra than mesons. The pT region in which the proton to pion ratio reaches
unity in central Au+Au collisions at sqrt(s_NN) = 62.4 GeV fits into a smooth
trend as a function of collision energy. The observed particle yields at very
low pT are comparable to extrapolations from higher pT for kaons, protons and
antiprotons. The net proton yield at mid-rapidity is found to be proportional
to the number of participant nucleons in Au+Au collisions at 62.4 and 200 GeV
energies.Comment: 5 pages, 3 figures, Presented at the Quark Matter 2006 conference in
Shanghai, Chin
Simulation of Jet Quenching Observables in Heavy Ion Collisions at the LHC
Large transverse momentum jets provide unique tools to study dense QCD matter
in high-energy heavy-ion collisions. Results from RHIC on suppression of high
transverse momentum particles in Au+Au collisions indicate a significant energy
loss of leading partons in the dense and strongly interacting matter formed in
these collisions. The LHC will collide Pb ions at sqrt(s_NN)=5500 GeV, where
the cross section of hard scattering will increase dramatically. Large
production rates, the large acceptance of the CMS calorimeters and tracking
system, combined with the capability of triggering on jets, will extend the
transverse momentum reach of charged particle spectra and nuclear modification
factors up to p_T>200 GeV/c.Comment: 6 pages, 5 figures. Presented at the 19th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions (QM2006), Shanghai, China,
November 14-20, 2006. [Grant numbers added in the acknowledgment.
Analysis of the BATSE Continuous MER data
The CGRO/BATSE database includes many types of data such as the 16-channel
continuous background or medium energy resolution burst data (CONT and MER data
types). We have calculated some four hundred burst's medium energy resolution
spectra and Principal Component Analysis has been applied. We found five
components can describe GRBs' spectra.Comment: 4 pages, 2 figures, accepted in Nuovo Ciment
Heavy Ion Physics at the LHC with CMS
The CMS detector is an excellent tool for measuring high mass and low-x phenomena in heavy-ion collisions. Its exceptional acceptance and resolution combined with a fast and sophisticated trigger offer the potential for unexpected discoveries
Az első hadronfizikai mérések a CERN CMS detektorral = The first hadronic physics measurements with the CERN CMS detector
A pályázat keretĂ©ben a CERN-ben az LHC beindulására kĂ©szĂĽltĂĽnk fel, illetve annak elsĹ‘ mĂ©rĂ©si adatait dolgoztuk fel, Ă©rtĂ©keltĂĽk ki Ă©s publikáltuk. Ezt a munkát világ egyik legnagyobb tudományos egyĂĽttműködĂ©sĂ©ben, a CMS kĂsĂ©rletben vĂ©geztĂĽk. Munkánk számos kutatási terĂĽletre (a QCD Ă©s a NehĂ©zion munkacsoportokban) Ă©s a kĂsĂ©rleti munka kĂĽlönbözĹ‘ fázisaira (hardver trigger, szoftver, adatkiĂ©rtĂ©kelĂ©s Ă©s publikáciĂł) terjedt ki. MegvalĂłsĂtottuk a CMS kĂsĂ©rletben az inelasztikus ĂĽtközĂ©seket nagy hatásfokkal Ă©rzĂ©kelĹ‘ rendszert háromfĂ©le detektorral. Több algoritmust is kifejlesztettĂĽnk az ĂĽtközĂ©si pont meghatározására. ValĂłs idejű esemĂ©nyválogatást dolgoztunk ki a keletkezett rĂ©szecskĂ©k száma illetve a detektorban általuk okozott jelek alapján. JavĂtottunk a rĂ©szecskepálya-rekonstrukciĂł hatásfokán Ă©s kibĹ‘vĂtettĂĽk az általa lefedett impulzustartományt. A világon elĹ‘ször megmĂ©rtĂĽk Ă©s publikáltuk a proton-proton ĂĽtközĂ©sekben keletkezett töltött rĂ©szecskĂ©k szög- Ă©s impulzuseloszlását a jelenlegi világrekord 2,36 TeV energián. Kidolgoztuk a töltött rĂ©szecskĂ©kre bomlĂł semleges rĂ©szecskĂ©k mĂ©rĂ©si mĂłdszerĂ©t. EredmĂ©nyeinket a CMS elsĹ‘ publikáciĂłján kĂvĂĽl kilenc nemzetközi konferencián Ă©s öt magyar nyelvű elĹ‘adásban, valamint 47 kĂsĂ©rleten belĂĽl tartott elĹ‘adásban ismertettĂĽk. Munkánk elismerĂ©sekĂ©nt vezetĹ‘ szerepet kaptunk a CMS kĂsĂ©rlet QCD fizikai programjának irányĂtásában. | Using the research grant, we prepared for the startup of the LHC at CERN. We have processed the first experimental data and published the results of the CMS experiment - one of the world's largest scientific collaborations. Our work extended to various scientific subfields (in the QCD and Heavy Ion groups) and to different phases of the experimental work (hardware trigger, software, data mining and publication). We have prepared triggers for the CMS experiment that are sensitive to inelastic collisions with a large efficiency, using three different detectors. We have developed algorithms to determine the position of the collision point. We have designed on-line triggers based on the number of created particles and on the signals in the tracking system created by them. We have improved the efficiency of the track reconstruction and extended the transverse momentum range covered. We have measured, for the first time, the angular and transverse momentum distributions of charged particles created in the p+p collisions at the highest collision energy ever reached in the laboratory (2.36 TeV). We worked on the reconstruction method of neutral particles based on their charged decay products. We have presented our results in the first publication of the CMS experiment on collision data, on nine international conferences and five Hungarian talks and seminars, and in 47 talks given within the CMS experiment. We have been awarded leadership role in the QCD physics group of CMS
Nagy transzverzális impulzusĂş rĂ©szecskĂ©k fizikája a RHIC Ă©s LHC gyorsĂtĂłkon = Physics of particles with high transverse momentum at the RHIC and LHC accelerators
A kutatást kĂsĂ©rleti rĂ©szecske- Ă©s magfizika tĂ©makörben vĂ©geztem a RHIC rĂ©szecskegyorsĂtĂł PHOBOS illetve az LHC gyorsĂtĂł CMS kĂsĂ©rletĂ©ben. A PHOBOS kĂsĂ©rlet nehĂ©zion-ĂĽtközĂ©seiben előállĂtott, atommagnál sokszorta sűrűbb anyag vizsgálatát segĂtette elĹ‘ a kĂĽlönbözĹ‘ tömegű atommagok kĂĽlönbözĹ‘ energiájĂş ĂĽtközĂ©seiben keletkezett nagy transzverzális impulzusĂş rĂ©szecskĂ©k mennyisĂ©gĂ©nek összehasonlĂtása. SokfĂ©le szabályosságot, skálázási Ă©s univerzalitási tulajdonságot találtunk az adatokban. Ezeket a vizsgálatokat azonosĂtott rĂ©szecskĂ©kkel is elvĂ©geztem. Ehhez kifejlesztettem a repĂĽlĂ©si idĹ‘n Ă©s az energiavesztesĂ©gen alapulĂł technikák pontosĂtását Ă©s egyĂĽttes használatát. Megfigyeltem skálázási tulajdonságokat a d+Au ĂĽtközĂ©sekben mĂ©rt spektrumokban, Ă©s azok sĂ©rĂĽlĂ©sĂ©t Au+Au ĂĽtközĂ©sekben. KollĂ©gáimmal kimutattam, hogy nagyon sok rĂ©szecske-keltĂ©si eredmĂ©ny meglepĹ‘en egyszerűen következik az ĂĽtközĹ‘ atommagok átfedĹ‘ tartományának geometriai tulajdonságaibĂłl, pl. pszeudorapiditás-eloszlások, elliptikus folyás illetve annak fluktuáciĂłi tekintetĂ©ben. Foglalkoztam a nagy transzverzális impulzusĂş rĂ©szecskĂ©k Ă©s az ĂĽtközĂ©sben keletkezett többi rĂ©szecske közötti korreláciĂłk vizsgálatával. A CMS kĂsĂ©rletben szimuláciĂłk segĂtsĂ©gĂ©vel elĹ‘kĂ©szĂĽleteket tettem a jet-ekkel kapcsolatos adatkiĂ©rtĂ©kelĂ©sre, valamint az elsĹ‘ publikáciĂłkra a rĂ©szecske-eloszlások tĂ©makörĂ©ben. EredmĂ©nyeimet 32 Ărásos munkában Ă©s folyĂłirat-cikkben közöltem. 31 elĹ‘adást tartottam a tĂ©mában, ezek közĂĽl 18-at nemzetközi konferencián. | I conducted my research in the field of experimental particle and nuclear physics with the PHOBOS experiment at the RHIC, and with the CMS experiment at the LHC accelerators. The comparison of the yield of particles with high transverse momentum created at various energies in collisions of heavy ions of various mass numbers helped the examination of the medium - much denser than a nucleus - created in these collisions at PHOBOS. Numerous regularities, scaling and universal features have been found in the data. I have also conducted these measurements with identified particles. To do that, I have developed methods to refine and combine the techniques based on time of flight and on specific energy loss. I have observed certain scaling features in d+Au spectra, and their breakdown in Au+Au collisions. We have shown that many features of the data on particle production simply follows from the geometrical features of the overlap zone between colliding nuclei, e.g. concerning pseudorapidity distributions, elliptic flow and its fluctuations. I have studied correlations between high transverse momentum particles and other particles created in the same collision. In the CMS experiment, I have made preparations for data analysis related to jets using computer simulations, and for the first publications concerning particle distributions. These results have been published in 32 written documents and journal articles. I have given 31 talks, 18 of them on international conferences
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