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Start Over Descriptor "electromagnetic probes" Topic nuclear physics
7 results on '"electromagnetic probes"'

1. Photon and dilepton observables: An experimental overview.

Author

Campbell, S.

Subjects
*DILEPTON production, *HEAVY ion collisions, *HADRONIC atoms, *QUANTUM chromodynamics, *NUCLEAR physics
Abstract

Dilepton and direct photon measurements in heavy ion collisions provide access to the early stages of the collision. Dilepton continuum measurements at SPS and RHIC show an excess consistent with broadening of the rho meson spectral function as a result of hadronic interactions. Direct photon measurements at RHIC and the LHC show an excess of low p T photons over the expected yield. This excess has a large azimuthal anisotropy with respect to the collision plane. Understanding the direct photon excess and its anisotropy has become an outstanding question in the field of heavy ion physics. This proceeding consists of a summary of new dilepton and direct photon experimental results shown at the 2017 International Conference on Ultrarelativistic Nucleus-Nucleus Collisions and presents them in the context of our current understanding of these electromagentic probes. [ABSTRACT FROM AUTHOR]

Published
2017
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2. SMASH – A new hadronic transport approach

Author

Jan Staudenmaier, Hannah Petersen, Sangwook Ryu, Dmytro Oliinychenko, and Markus Mayer

Subjects
Nuclear and High Energy Physics, Nuclear Theory, nucl-th, Hadron, FOS: Physical sciences, bulk observables, nucl-ex, Atomic, 01 natural sciences, Nuclear Theory (nucl-th), Nuclear physics, High Energy Physics - Phenomenology (hep-ph), Particle and Plasma Physics, 0103 physical sciences, transport theory, ddc:530, Nuclear, Nuclear Experiment (nucl-ex), Nuclear Experiment, 010306 general physics, Physics, Excitation function, Quantum Physics, 010308 nuclear & particles physics, High Energy Physics::Phenomenology, Elliptic flow, Molecular, hep-ph, Plasma, Nuclear & Particles Physics, relativistic heavy ion reactions, Baryon, High Energy Physics - Phenomenology, Afterburner, Quark–gluon plasma, Heavy ion, electromagnetic probes, Astronomical and Space Sciences
Abstract

Microscopic transport approaches are the tool to describe the non-equilibrium evolution in low energy collisions as well as in the late dilute stages of high-energy collisions. Here, a newly developed hadronic transport approach, SMASH (Simulating Many Accelerated Strongly-interacting Hadrons) is introduced. The overall bulk dynamics in low energy heavy ion collisions is shown including the excitation function of elliptic flow employing several equations of state. The implications of this new approach for dilepton production are discussed and preliminary results for afterburner calculations at the highest RHIC energy are presented and compared to previous UrQMD results. A detailed understanding of a hadron gas with vacuum properties is required to establish the baseline for the exploration of the transition to the quark-gluon plasma in heavy ion collisions at high net baryon densities., 4 pages, 4 figures, accepted contribution to the proceedings of Quark Matter 2018

Published
2019
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3. HADRON PHYSICS AT ELSA.

Author

LANG, MICHAEL

Subjects
*NUCLEAR reactions, *MESONS, *RESONANCE, *EXPERIMENTS, *PARTICLES (Nuclear physics), *NUCLEAR physics
Abstract

Excitation of the nucleon at low Q2 and energies up to several GeV reveals clearly measurable structures that indicate the existance of resonances. A major goal of experiments carried out at the accelerator facility ELSA in Bonn/Germany is to explore this resonance structure, which gives valuable input to models describing the QCD structure of the nucleon. Resonance contributions for nuclear reaction channels, such as single pion, two pion and eta production from the experiments can be given using the Bonn-Gatchina partial wave analysis1. The talk at the conference MESON 2008 in Krakow gave an overview of results from experiments at ELSA and plans for the near future. [ABSTRACT FROM AUTHOR]

Published
2009

4. Direct Photons at the PHENIX Experiment: From Large to Small Systems

Author

Veronica Canoa Roman

Subjects
Physics, Large Hadron Collider, Photon, Scattering, lcsh:A, photon scaling, Computer Science::Digital Libraries, Nuclear physics, TheoryofComputation_MATHEMATICALLOGICANDFORMALLANGUAGES, direct photons, Thermal, Computer Science::Programming Languages, electromagnetic probes, lcsh:General Works, Multiplicity (chemistry), Nuclear Experiment, Anisotropy, Nucleon, Scaling
Abstract

Direct photons are a unique probe to study the properties of the medium created in heavy ion collisions. Low transverse momentum ( p T ) direct photons are of special interest since thermal photons are supposed to be dominant, while at high p T direct photons come from initial hard scattering (pQCD). PHENIX has observed a large excess of direct photon yield as well as large azimuthal anisotropy at low p T in Au+Au collisions at the c.m.s energy per nucleon pair s N N = 200 GeV. The mechanism to produce a large direct photon yield with a large elliptic anisotropy ( v 2 ) is not well understood yet. PHENIX has made systematic measurements of direct photons with different collision energies and system configurations. It has been found that direct photon yield d N γ / d η is proportional to charge particle multiplicity ( d N c h / d η ) 1 . 25 . This behavior holds for beam energies measured both at RHIC and at the LHC in large systems. This scaling suggests that there is a transition from p+p to A+A system which could be understood with the analysis of smaller systems like p+Au and d+Au.

Published
2019
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5. Exploring the Structure of the Bound Proton with Deeply Virtual Compton Scattering

Author

A. El Alaoui, Alessandro Rizzo, C. Ayerbe Gayoso, M. Khandaker, R. Paremuzyan, Nicholas Zachariou, O. Soto, Andrea Celentano, Nicholas M. Harrison, Gerard Gilfoyle, D. P. Watts, S. Fegan, D. Sokhan, V. Crede, K. Livingston, M. Garçon, Sandra K. Johnston, R. A. Montgomery, Jie Zhang, F. X. Girod, M. Battaglieri, M. Contalbrigo, G. Gavalian, E. Golovatch, S. Strauch, Aditya R. Khanal, S. Niccolai, A. Filippi, M. Ripani, R. Dupre, N A Baltzell, K. L. Giovanetti, A. D'Angelo, E. L. Isupov, G. Khachatryan, Dustin Keller, Larry Weinstein, P. Lenisa, Yordanka Ilieva, M. Defurne, N. Markov, Chaden Djalali, Michael Wood, Laura Clark, E. De Sanctis, F. Sabatié, D. Heddle, K. A. Griffioen, T. Mineeva, L. Barion, K. Hafidi, J. Poudel, Taya Chetry, C. Munoz Camacho, P. L. Cole, Iu. Skorodumina, G. Angelini, P. Rossi, T. B. Hayward, D. Protopopescu, Z. W. Zhao, B. McKinnon, F. Hauenstein, Friedrich Klein, L. Lanza, B. Torayev, A Fradi, S. Diehl, C. Salgado, V. P. Kubarovsky, D. Riser, G. Ciullo, O. Pogorelko, M. Mirazita, H. Egiyan, F. Bossu, G. Rosner, P. Eugenio, Y. Prok, D. S. Carman, L. El Fassi, E. Pasyuk, M. Taiuti, C. W. Kim, Zein-Eddine Meziani, F. Cao, M. L. Kabir, S. E. Kuhn, M. Hattawy, H. Voskanyan, A. I. Ostrovidov, D. G. Jenkins, I. J. D. MacGregor, M. Guidal, Rong Wang, N. Dashyan, D. G. Ireland, M Ehrhart, A. S. Biselli, N. Gevorgyan, R. W. Gothe, M. Holtrop, I. Bedlinskiy, Luciano Pappalardo, Martin K. Mayer, A. Deur, W. Kim, M. Khachatryan, Nikolaos Sparveris, W. K. Brooks, S. Adhikari, Y. G. Sharabian, R. De Vita, D. Marchand, H. S. Jo, X. Wei, R. A. Schumacher, S. Bültmann, T. A. Forest, S. Stepanyan, Simonetta Liuti, M. Ungaro, Y. Perrin, K. Hicks, P. Chatagnon, P. Nadel-Turonski, N. Tyler, J. A. Tan, E. Voutier, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CLAS, Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), and Université Grenoble Alpes (UGA)

Subjects
generalized parton distribution, Proton, EMC effect, Nuclear Theory, General Physics and Astronomy, Virtual particle, parton: distribution function, Parton, Electron, 01 natural sciences, 7. Clean energy, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Electromagnetic probes, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment (nucl-ex), Form factors, Electromagnetic probes, Nuclear Structure, Deep Virtual Compton Scattering, Quark models, Electron-ion collisions, Nuclear structure & decays, Nucleon distribution, electron: beam, Nuclear Experiment, Physics, Settore FIS/04, Form factors, nucleon, matter: effect, kinematics, Quark models, Nucleon, spin: asymmetry, accelerator, FOS: Physical sciences, Socio-culturale, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Structure, Deep Virtual Compton Scattering, Nuclear physics, PE2_2, PE2_1, deeply virtual Compton scattering, CLAS, 0103 physical sciences, structure, 010306 general physics, PE2_3, Electron-ion collisions, Nuclear Physics, Scattering, Nuclear structure &amp, Compton scattering, Automatic Keywords, Physics::Accelerator Physics, High Energy Physics::Experiment, Nucleon distribution, spectrometer, decays, experimental results, photon: virtual
Abstract

In the past two decades, deeply virtual Compton scattering of electrons has been successfully used to advance our knowledge of the partonic structure of the free proton and investigate correlations between the transverse position and the longitudinal momentum of quarks inside the nucleon. Meanwhile, the structure of bound nucleons in nuclei has been studied in inclusive deep-inelastic lepton scattering experiments off nuclear targets, showing a significant difference in longitudinal momentum distribution of quarks inside the bound nucleon, known as the EMC effect. In this work, we report the first beam spin asymmetry (BSA) measurement of exclusive deeply virtual Compton scattering (DVCS) off a proton bound in $^4$He. The data used here were accumulated using a $6$ GeV longitudinally polarized electron beam incident on a pressurized $^4$He gaseous target placed within the CLAS spectrometer in Hall-B at the Thomas Jefferson National Accelerator Facility. The azimuthal angle ($\phi$) dependence of the BSA was studied in a wide range of virtual photon and scattered proton kinematics. The $Q^2$, $x_B$, and t dependencies of the BSA on the bound proton are compared with those on the free proton. In the whole kinematical region of our measurements, the BSA on the bound proton is smaller by 20\% to 40\%, indicating possible medium modification of its partonic structure.

Published
2019
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6. Direct photon measurements in pp and Pb–Pb collisions with the ALICE experiment

Author

Acharya, Shreyasi, Adam, Jaroslav, Adamová, Dagmar, Adolfsson, Jonatan, Aggarwal, Madan M., Aglieri Rinella, G, Agnello, Michelangelo, Agrawal, Nikita, Ahammed, Zubayer, Ahmad, N, Ahn, SU, Alme, Johan, Altenkaemper, Lucas, Arsene, Ionut Christian, Bätzing, Paul Christoph, Djuvsland, Øystein, Dordic, Olja, Helstrup, Håvard, Hetland, Kristin Fanebust, Kileng, Bjarte, Langøy, Rune, Lardeux, Antoine Xavier, Lien, Jørgen André, Lindal, Svein, Lønne, Per-Ivar, Mahmood, Sohail Musa, Milosevic, Jovan, Nesbø, Simon Voigt, Nystrand, Joakim, Rehman, Attiq Ur, Richter, Matthias Rudolph, Røed, Ketil, Røhrich, Dieter, Skaali, Toralf Bernhard, Tambave, Ganesh Jagannath, Tveter, Trine Spedstad, Ullaland, Kjetil, Velure, Arild, Wagner, Boris, Wikne, Jon Christopher, Zhang, Hui, Zhao, Chengxin, Zhou, Zhuo, Zhu, Hongsheng, Qvigstad, Henrik, Aiola, Salvatore, Akindinov, Alexander, Alam, Sk Noor, Alba, José Luis Bazo, Aleksandrov, Dimitry, ALICE, Collaboration, Laboratoire de physique subatomique et des technologies associées (SUBATECH), Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), ALICE, Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), and Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST)

Subjects
Photon, heavy ion: scattering, transverse momentum: high, parton: distribution function, Parton, 01 natural sciences, 7. Clean energy, hard scattering, ALICE, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], photons, Nuclear Experiment, Quantum chromodynamics, Physics, radiation: thermal, Observable, photon: direct production, CERN LHC Coll, space-time, Thermal radiation, flow, electromagnetic probes, photon: yield, Particle Physics - Experiment, Nuclear and High Energy Physics, Particle physics, p p: scattering, talk: Chicago 2017/02/06, collective, NLO, pQCD, Nuclear physics, Momentum, direct photons, heavy-ions, 0103 physical sciences, quantum chromodynamics, Matematikk og Naturvitenskap: 400::Fysikk: 430::Kjerne- og elementærpartikkelfysikk: 431 [VDP], 010306 general physics, lead, 010308 nuclear & particles physics, Scattering, High Energy Physics::Phenomenology, temperature, Distribution function, electromagnetic, QGP, High Energy Physics::Experiment, momentum: low, experimental results
Abstract

Direct photon production in heavy-ion collisions provides a valuable set of observables to study the hot QCD medium. The direct photons are produced at different stages of the collision and escape the medium unaffected. In heavy-ion collisions, the direct photon yield at high transverse momentum ( p T > 5 GeV / c ) is dominated by prompt photons produced in hard scattering of incoming partons and provides information on nuclear parton distribution functions and on the initial parton dynamics. The low momentum component ( p T ≲ 5 GeV / c ) of the direct photon production is dominated by thermal radiation by the hot and dense matter created, carrying information on its space-time evolution, collective flow and temperature. We present recent ALICE results on direct photon production Pb-Pb collisions at 2.76 TeV and on direct photon production in pp at 7 TeV using isolation techniques. The results are compared to theoretical predictions and previous measurements.

Published
2017
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7. Spin observables in deuteron-proton radiative capture at intermediate energies

Author

Mehmandoost-Khajeh-Dad, A.A., Amir-Ahmadi, HR, Bacelar, JCS, van den Berg, AM, Castelijns, R, Deltuva, A, van Garderen, ED, Glockle, W, Golak, J, Kalantar-Nayestanaki, N, Kamada, H, Kis, M, Koohi-Fayegh-Dehkordi, R, Mahjour-Shafiei, M, Mardanpour, H, Messchendorp, JG, Nogga, A, Sauer, P, Shende, SV, Skibinski, R, Witala, H, Wortche, HJ, Glöckle, W., Löhner, H., Mardanpur, H., Skibilski, R., Research unit Nuclear & Hadron Physics, Research unit Astroparticle Physics, and KVI - Center for Advanced Radiation Technology

Subjects
Nuclear and High Energy Physics, Particle physics, Proton, Nuclear Theory, FOS: Physical sciences, ANALYZING POWERS, Nuclear physics, Radiative transfer, Nuclear force, NUCLEAR-FORCES, SPECTROMETER, Tensor, Nuclear Experiment (nucl-ex), Nuclear Experiment, Spin-½, nuclear forces, electromagnetic probes, radiative capture, Elastic scattering, Physics, CHIRAL LAGRANGIANS, ELASTIC-SCATTERING, Anomaly (physics), Nucleon
Abstract

A radiative deuteron-proton capture experiment was carried out at KVI using polarized-deuteron beams at incident energies of 55, 66.5, and 90 MeV/nucleon. Vector and tensor-analyzing powers were obtained for a large angular range. The results are interpreted with the help of Faddeev calculations, which are based on modern two- and three-nucleon potentials. Our data are described well by the calculations, and disagree significantly with the observed tensor anomaly at RCNP., 10 pages, 4 figures, submitted to PLB

Published
2005

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