Página 15 dos resultados de 19478 itens digitais encontrados em 0.029 segundos

Detection of Minimum-Ionizing Particles and Nuclear Counter Effect with Pure BGO and BSO Crystals with Photodiode Read-out

Ueno, K.; Sahu, S. K.; Peng, K. C.; Hou, W. S.; Wang, C. H.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/04/1997
Relevância na Pesquisa
45.85%
Long BGO (Bismuth Germanate) and BSO (Bismuth Silicate) crystals coupled with silicon photodiodes have been used to detect minimum-ionizing particles(MIP). With a low noise amplifier customized for this purpose, the crystals can detect MIPs with an excellent signal-to-noise ratio. The NCE(Nuclear Counter Effect} is also clearly observed and measured. Effect of full and partial wrapping of a reflector around the crystal on light collection is also studied.; Comment: 18 pages, including 5 figures; LaTeX and EPS

Hadrons in Medium -- Theory meets Experiment

Mosel, Ulrich
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.85%
In this talk I give a short review of theoretical results on the properties of hadrons in cold, equilibrium nuclear matter. I then discuss the observable consequences of any changes of these properties inside the medium in actual experiments. I demonstrate that any experimental verification of in-medium effects requires a state-of-the-art treatment of the reaction dynamics and, in particular, also the final state interactions.; Comment: Invited talk at MENU07, Juelich, Germany, Sept. 2007; ref added

Toward the Limits of Matter: Ultra-relativistic nuclear collisions at CERN

Schukraft, Jurgen; Stock, Reinhard
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 26/05/2015
Relevância na Pesquisa
45.85%
Strongly interacting matter as described by the thermodynamics of QCD undergoes a phase transition, from a low temperature hadronic medium to a high temperature quark-gluon plasma state. In the early universe this transition occurred during the early microsecond era. It can be investigated in the laboratory, in collisions of nuclei at relativistic energy, which create "fireballs" of sufficient energy density to cross the QCD Phase boundary. We describe 3 decades of work at CERN, devoted to the study of the QCD plasma and the phase transition. From modest beginnings at the SPS, ultra-relativistic heavy ion physics has evolved today into a central pillar of contemporary nuclear physics and forms a significant part of the LHC program.; Comment: To appear in "60 Years of CERN Experiments and Discoveries", Editors H. Schopper and L. di Lella, World Scientific Publishing, Singapore, 2015

Relating multihadron production in hadronic and nuclear collisions

Sarkisyan, Edward K. G.; Sakharov, Alexander S.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.85%
The energy-dependence of charged particle mean multiplicity and pseudorapidity density at midrapidity measured in nucleus-nucleus and (anti)proton-proton collisions are studied in the entire available energy range. The study is performed using a model, which considers the multiparticle production process according to the dissipating energy of the participants and their types, namely a combination of the constituent quark picture together with Landau relativistic hydrodynamics. The model reveals interrelations between the variables under study measured in nucleus-nucleus and nucleon-nucleon collisions. Measurements in nuclear reactions are shown to be well reproduced by the measurements in (anti)proton-proton interactions common and the corresponding fits are presented. Different observations in other types of collisions are discussed in the framework of the proposed model. Predictions are made for measurements at the forthcoming LHC energies.; Comment: Europ. Phys. J. C (to appear). Recently CMS reported (arXiv:1005.3299) on the midrapidity density value of 5.78 +/- 0.01(stat) +/- 0.23(syst) in pp collisons at 7 TeV, which agrees well with the value of 5.8 of our predictions

Study of the neutral mesons in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV in the ALICE experiment at LHC

Leardini, Lucia; Collaboration, for the ALICE
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/12/2014
Relevância na Pesquisa
45.85%
The $\pi^{0}$ and $\eta$ meson production in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV is studied with the ALICE experiment at the LHC. The $\pi^{0}$ invariant yields and nuclear modification factor $R_{\mbox{AA}}$ are presented here in six centrality classes. The results are a combined measurement using the Photon Conversion Method (PCM) and the PHOS detector, in the transverse momentum range 0.4 $< p_{\mbox{T}} <$ 12 GeV/$c$. The $\pi^{0}$ $R_{\mbox{AA}}$ is studied in different centrality classes and compared with results from experiments at lower energies, both as a function of transverse momentum. The $\eta$ meson production is studied using the PCM and the EMCal detector. The combination of the individual results will make possible the measurement of the $\eta$ differential invariant cross section as a function of transverse momentum from 1 to 22 GeV/$c$ in different centrality classes.; Comment: 4 pages, 3 figures, proceedings for the Hot Quarks 2014 workshop, Las Negras, Cabo de Gata Natural Park, Andalusia, Spain

Cold nuclear matter physics at forward rapidities from d+Au collisions in PHENIX

Chiu, Mickey
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/09/2011
Relevância na Pesquisa
45.85%
We present measurements by the PHENIX experiment at RHIC of di-hadron pair production in \dAu collisions where the particles in the pair are varied across a wide range of pseudorapidity, out to $\eta = 3.8$. With di-hadrons, varying the $p_T$ and rapidity of the particles in the di-hadron pair allows studying any effects as a function of partonic $x$ in the nucleus. These di-hadron measurements might probe down to parton momentum fractions x $\sim$ $10^{-3}$ in the gold nucleus, where the interesting possibility of observing gluon saturation effects at RHIC is the greatest. Our measurements show that the correlated yield of back-to-back pairs in \dAu collisions is suppressed by up to an order of magnitude relative to \pp collisions, and increases with greater nuclear path thickness and with a selection for lower x in the Au nucleus.; Comment: To appear in the proceedings of Quark Matter 2011 (QM 2011), Annecy, France, 23-28 May 2011

A Nuclear Physics Program at the ATLAS Experiment at the CERN Large Hadron Collider

Aronson, S.; Assamagan, K.; Gordon, H.; Leite, M.; Levine, M.; Nevski, P.; Takai, H.; White, S.; Cole, B.; Nagle, J. L.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 13/12/2002
Relevância na Pesquisa
45.85%
The ATLAS collaboration has significant interest in the physics of ultra-relativistic heavy ion collisions. We submitted a Letter of Intent to the United States Department of Energy in March 2002. The following document is a slightly modified version of that LOI. More details are available at: http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/SM/ions; Comment: Letter of Intent submitted to the United States Department of Energy Nuclear Physics Division in March 2002 (revised version)

Results on High p_T Particle Production from the PHENIX Experiment at RHIC

Reygers, Klaus; Collaboration, for the PHENIX
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 12/10/2003
Relevância na Pesquisa
45.85%
Transverse momentum (p_T) spectra of neutral pions and charged hadrons measured in Au+Au and d+Au collisions at sqrt{s_NN}=200 GeV by the PHENIX experiment at RHIC are compared to p+p reference spectra at the same sqrt{s_NN}. In central Au+Au collisions a factor 4-5 suppression for neutral pions and charged hadrons with p_T > 5 GeV/c is found relative to the p+p reference scaled by the nuclear overlap function . In contrast, such a suppression of high p_T particles is absent in d+Au collisions.; Comment: To appear in the proceedings of the 8th International Conference on Nucleus-Nucleus Collisions (NN 2003), Moscow, Russia, 17-21 Jun 2003 (4 pages, 3 figures), V1: error fixed in caption of Fig. 1

Space-Time Properties of Hadronization from Nuclear Deep Inelastic Scattering

Brooks, W. K.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 29/10/2003
Relevância na Pesquisa
45.85%
Hadronization, the process by which energetic quarks evolve into hadrons, has been studied phenomenologically for decades. However, little experimental insight has been gained into the space-time features of this fundamentally non-perturbative process. New experiments at Jefferson Lab, in combination with HERMES data, will provide significant new insights into the phenomena connected with hadron formation in deep inelastic scattering, such as quark energy loss in-medium, gluon emission, and color field restoration.; Comment: 10 pages, no figures Invited talk given at the Second International Conference on Nuclear and Particle physics with CEBAF at Jefferson Laboratory (NAPP 2003) Submitted to Fizika B for publication

General properties of the pion production reaction in nuclear matter

Camerini, P.; Fragiacomo, E.; Grion, N.; Piano, S.; Rui, R.; Clark, J.; Felawka, L.; Gibson, E. F.; Hofman, G.; Mathie, E. L.; Meier, R.; Moloney, G.; Ottewell, D.; Raywood, K.; Sevior, M. E.; Smith, G. R.; Tacik, R.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 16/01/2004
Relevância na Pesquisa
45.85%
The pion production reaction $\pi^+ \to \pi^+\pi^{\pm}$ on $^{45}Sc$ was studied at incident pion energies of $T_{\pi^{+}}$ = 240, 260, 280, 300, and 320 MeV. The experiment was performed using the $M11$ pion-channel at TRIUMF, and multiparticle events, ($\pi^+,\pi^+\pi^{\pm}$) and ($\pi^+,\pi^+\pi^{\pm}p$), were detected with the CHAOS spectrometer. Results are reported in the form of both differential and total cross sections, and are compared to theoretical predictions and the reaction phase space. The present investigation of the T-dependence of the $\pi^+ A \to \pi^+\pi^{\pm} A'$ reaction complements earlier examinations of the A-dependence of the reaction, which was measured using $^{2}H$, $^{4}He$, $^{12}C$, $^{16}O$, $^{40}Ca$, and $^{208}Pb$ targets at $\sim$280 MeV. Some general properties of the pion-induced pion production reaction in nuclear matter will be presented, based on the combined results of the two studies.; Comment: 23 pages, Latex, accepted for publication in Nucl. Phys. A

Estimation of the amount of the nuclear transformation products formed under explosion-induced compression of a substance to the superdense state

Adamenko, S. V.; Adamenko, A. S.; Kossko, I. A.; Kurochkin, V. D.; Kovylyaev, V. V.; Ponomarev, S. S.; Andreev, A. V.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 29/04/2004
Relevância na Pesquisa
45.85%
In the present work carried out at the Electrodynamics Laboratory Proton-21 with the use of X-ray electron probe microanalysis (XEPMA) and glow-discharge mass spectrometry (GDMS) techniques, we study the chemical composition of a substance formed as a result of the explosion-induced compression of solid targets and deposited on the surfaces of accumulating screens. We established that the explosion products contain chemical elements which were not included in the composition of the initial materials of targets and accumulating screens or were included in them as impurities in quantities by 3...7 and more orders in magnitude less than those detected after the experiment. We conclude that the regular appearance of chemical elements, which were not included in the composition of the initial materials of targets and accumulating screens, in the explosion products is the consequence of a nuclear transformation of a part of their material, i.e., is the fact testifying to both the running of the nucleosynthesis reactions upon the explosion-induced destruction of targets and to the first realized possibility of controlled creation of the conditions for their running in a laboratory setup.; Comment: 14 pages, 6 figures, 6 tables

Open heavy flavor measurements with the PHENIX experiment at RHIC

Averbeck, Ralf; Collaboration, for the PHENIX
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 06/10/2004
Relevância na Pesquisa
45.85%
The PHENIX experiment has measured single electron spectra at RHIC in proton-proton (p-p), deuteron-gold (d-Au), and gold-gold (Au-Au) collisions at an available energy per nucleon-nucleon pair of sqrt{s_NN} = 200 GeV. Contributions from photonic sources, i.e. Dalitz decays of light mesons and photon conversions, are subtracted from the inclusive spectra. The remaining non-photonic single electron spectra are dominated by semileptonic decays of particles carrying heavy flavor. Implications of these systematic measurements for heavy flavor production in cold and hot nuclear systems are discussed.; Comment: 7 pages, 5 figures, presented at Hot Quarks 2004, Taos, New Mexico, USA

The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles

G0 Collaboration; Androic, D.; Armstrong, D. S.; Arvieux, J.; Asaturyan, R.; Averett, T. D.; Bailey, S. L.; Batigne, G.; Beck, D. H.; Beise, E. J.; Benesch, J.; Benmokhtar, F.; Bimbot, L.; Birchall, J.; Biselli, A.; Bosted, P.; Breuer, H.; Brindza, P.; Ca
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 03/03/2011
Relevância na Pesquisa
45.85%
In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. The overall design and performance of this experimental system is discussed.; Comment: Submitted to Nuclear Instruments and Methods

Measurements of the inclusive jet cross section and jet fragmentation in pp collisions with the ALICE experiment at the LHC

Ma, Rongrong; Collaboration, for the ALICE
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.85%
Jet reconstruction and jet fragmentation variables provide important information to study the interaction between hard scattered partons and the Quark-Gluon Plasma. This paper presents the measurement of the inclusive cross section for fully reconstructed jets in pp collisions at sqrt(s) = 2.76 TeV, which provides an essential reference for jet measurements in Pb-Pb collisions at the same sqrt(s_NN). In addition, we report jet fragmentation measurements for charged particle jets in pp collisions at sqrt(s) = 7 TeV. These measurements utilize the ALICE central barrel tracking system to detect charged particles with good efficiency above 150 MeV/c, together with the Electromagnetic Calorimeter (EMCal). The jet cross section and fragmentation measurements are compared to theoretical calculations and Monte Carlo generators.; Comment: 4 page, 6 figures, proceeding for the Fifth International Conference on Hard and Electromagnetic Probes of High Energy Nuclear Collisions (Hard Probes 2012), May 27 - June 1, Cagliari, Italy

Charged particle jet measurements with the ALICE experiment in proton-proton collisions at the LHC

Collaboration, S. K. Prasad for the ALICE
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 24/08/2012
Relevância na Pesquisa
45.85%
We present preliminary results of measurements of charged particle jet properties in proton-proton collisions at $\sqrt{s}$ = 7 TeV using the ALICE detector. Jets are reconstructed using $\rm anti-k_{T}, k_{T}$ and SISCone jet finding algorithms with resolution parameter $R=0.4$ in the range of transverse momentum from 20 to 100 GeV/$c$ in the midrapidity region ($\mid\eta\mid\textless$ 0.5). The uncorrected charged jet spectra obtained using the three different jet finders show good agreement. The data are compared to predictions from PYTHIA-Perugia0, PYTHIA-Perugia2011, and PHOJET. The mean charged particle multiplicity in leading jets increases with increasing jet $p_{\rm T}$ and is consistent with model predictions. The radial distributions of transverse momentum about the jet direction and the distributions of the average radius containing 80% of the total jet $p_{\rm T}$ found in the jet cone ($R = 0.4$ in this analysis), indicate that high $p_{\rm T}$ jets are more collimated than low $p_{\rm T}$ jets.; Comment: 6 pages, 6 figures, Conference Proceedings submitted for the 28th Winter Workshop on Nuclear Dynamics, Puerto Rico, April 7-14, 2012

J/psi elliptic flow measurement in Pb-Pb collisions at \sqrt{s_{NN}} = 2.76 TeV at forward rapidity with the ALICE experiment

Massacrier, L.; Collaboration, for the ALICE
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.85%
J/psi suppression induced by color screening of its constituent quarks was proposed 26 years ago as a signature of the formation of a quark gluon plasma in heavy-ion collisions. Recent results from ALICE in Pb-Pb collisions exhibit a smaller suppression with respect to previous measurements at the SPS and RHIC. The study of azimuthal anisotropy in particle production gives information on the collective hydrodynamic expansion at the early stage of the fireball, where the matter created in high-energy nuclear collisions is expected to be in a deconfined state. In particular, J/psi elliptic flow v2 is important to test the degree of thermalization of heavy quarks. Together with the production yields, the elliptic flow is a powerful observable to address the question of suppression and regeneration of J/psi in QGP. We present the first inclusive J/psi elliptic flow measurement performed with the muon spectrometer of ALICE, in Pb-Pb collisions, at forward rapidity. Integrated and pT-differential v2 results are presented and a comparison with recent STAR results and with a parton transport model is also performed.; Comment: proceeding of Hard Probes 2012 conference

Limits on Majoron-emitting double-beta decays of Xe-136 in the KamLAND-Zen experiment

Collaboration, KamLAND-Zen; :; Gando, A.; Gando, Y.; Hanakago, H.; Ikeda, H.; Inoue, K.; Kato, R.; Koga, M.; Matsuda, S.; Mitsui, T.; Nakada, T.; Nakamura, K.; Obata, A.; Oki, A.; Ono, Y.; Shimizu, I.; Shirai, J.; Suzuki, A.; Takemoto, Y.; Tamae, K.; Uesh
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.85%
We present limits on Majoron-emitting neutrinoless double-beta decay modes based on an exposure of 112.3 days with 125 kg of Xe-136. In particular, a lower limit on the ordinary (spectral index n = 1) Majoron-emitting decay half-life of Xe-136 is obtained as T_{1/2}^{0\nu\chi^{0}} > 2.6 x 10^{24} yr at 90% C.L., a factor of five more stringent than previous limits. The corresponding upper limit on the effective Majoron-neutrino coupling, using a range of available nuclear matrix calculations, is < (0.8 - 1.6) x 10^{-5}. This excludes a previously unconstrained region of parameter space and strongly limits the possible contribution of ordinary Majoron emission modes to 0\nu\beta\beta decay for neutrino masses in the inverted hierarchy scheme.; Comment: 4 pages, 3 figures (1 figure added). Published version in PRC rapid communication

New experiment on the neutron radiative decay

U., Khafizov R.; A., Kolesnikov I.; V., Tolokonnikov S.; D., Torokhov V.; A., Solovei V.; R., Kolhidashvili M.; A, Konorov I.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/10/2009
Relevância na Pesquisa
45.85%
The report is dedicated to the preparation of the new experiment on the neutron radiative decay what is conducted for the last years. We started the experimental research of this neutron decay branch with the experiment conducted at ILL in 2002 and continued in another experiment at the second and third cycles at the FRMII reactor of the Technical University of Munich in 2005. In the first experiment we succeeded in measuring only the upper limit on the relative intensity (B.R.) of the radiative neutron decay and in the second we succeeded in discovering events of radiative neutron decay and measure its B.R.=(3.2+-1.6)10-3 (with C.L.=99.7% and gamma quanta energy over 35 keV). The obtained average B.R. value was approximately twice the theoretical value calculated earlier within the framework of the standard electroweak model. However, due to significant experimental error it would be preliminary to deduce that based on this finding a deviation from the standard model has been observed. To prove or disprove the existence of a deviation it is necessary to conduct a new experiment that would allow to measure the radiative peak in timing spectra with precision in the order of 1%. By the present time we have prepared a new experiment the main result of which would be the measurement of B.R. for the radiative branch of neutron decay with this precision.; Comment: Report on conferences ISINN-17...

Measurement of jpsi production in p+p collisions at \sqrts = 500 GeV at STAR experiment

Ma, Rongrong; Collaboration, on behalf of the STAR
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 21/09/2015
Relevância na Pesquisa
45.85%
Quarkonium measurements in heavy-ion collisions play an essential role in understanding the hot, dense medium created in such collisions. As a reference, their production mechanism in p+p collisions needs to be thoroughly understood. In this paper, we report the measurement of inclusive cross section of jpsi with transverse momentum (pT) above 4 GeV/c at mid-rapidity in p+p collisions at \sqrts = 500 GeV by the STAR experiment. The ratio of the yield of psi(2S) to jpsi integrated over 4 < pT < 12 GeV/c is also presented. Furthermore, the jpsi yields are studied in different event multiplicity bins in different jpsi pT regions, where the low pT measurement is enabled by the newly installed Muon Telescope Detector. A strong increase of the relative jpsi yield with the event multiplicity is observed for all pT with significant pT dependence.; Comment: 4 page, 7 figures, proceeding for the 7th International Conference on Hard and Electromagnetic Probes of High Energy Nuclear Collisions (Hard Probes 2015), June 29 - July 3, Montreal, Canada

Measurement of D$_s^+$ production and nuclear modification factor in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV

ALICE Collaboration
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 24/09/2015
Relevância na Pesquisa
45.85%
The production of prompt D$_s^+$ mesons was measured for the first time in collisions of heavy nuclei with the ALICE detector at the LHC. The analysis was performed on a data sample of Pb-Pb collisions at a centre-of-mass energy per nucleon pair, $\sqrt{s_{\rm NN}}$, of 2.76 TeV in two different centrality classes, namely 0-10% and 20-50%. D$_s^+$ mesons and their antiparticles were reconstructed at mid-rapidity from their hadronic decay channel D$_s^+\rightarrow\phi\pi^+$, with $\phi\rightarrow$K$^-$K$^+$, in the transverse momentum intervals $4< p_{\rm T}<12$ GeV/$c$ and $6< p_{\rm T}<12$ GeV/$c$ for the 0-10% and 20-50% centrality classes, respectively. The nuclear modification factor $R_{\rm AA}$ was computed by comparing the $p_{\rm T}$-differential production yields in Pb-Pb collisions to those in proton-proton (pp) collisions at the same energy. This pp reference was obtained using the cross section measured at $\sqrt{s}= 7$ TeV and scaled to $\sqrt{s}= 2.76$ TeV. The $R_{\rm AA}$ of D$_s^+$ mesons was compared to that of non-strange D mesons in the 10% most central Pb-Pb collisions. At high $p_{\rm T}$ ($8< p_{\rm T}<12$ GeV/$c$) a suppression of the D$_s^+$-meson yield by a factor of about three, compatible within uncertainties with that of non-strange D mesons...