scholarly journals Study of the Polarization Deterioration During Physics Stores in RHIC Polarized Proton Runs

2016 ◽  
Vol 40 ◽  
pp. 1660091
Author(s):  
Z. Duan ◽  
Q. Qin ◽  
M. Bai ◽  
T. Roser
Keyword(s):  
Beam Energy ◽  
Heavy Ion ◽  
High Energy ◽  
Great Success ◽  
Relativistic Heavy Ion Collider ◽  
Proton Beams ◽  
Beam Control ◽  
The Past ◽  
Polarized Proton ◽  
The World

As the only high energy polarized proton collider in the world, the Relativistic Heavy Ion Collider (RHIC) has achieved a great success in colliding polarized proton beams up to 255GeV per beam energy with over 50% average store polarizations for spin physics studies. With the help of Siberian snakes as well as outstanding beam control during the acceleration, polarization loss during acceleration up to 100 GeV is negligible. However, about 10% polarization loss was observed between acceleration from 100 GeV to 255 GeV. In addition, a mild polarization deterioration during long store for physics data taking was also observed. In this paper, studies in understanding the store depolarizing mechanism is reported, including the analysis of polarization deterioration data based on the past couple of RHIC polarized proton runs.

scholarly journals RECENT RESULTS ON HIGH-ENERGY SPIN PHENOMENA OF GLUONS AND SEA-QUARKS IN POLARIZED PROTON-PROTON COLLISIONS AT RHIC AT BNL

2014 ◽  
Vol 25 ◽  
pp. 1460033 ◽  
Author(s):  
BERND SURROW
Keyword(s):  
Heavy Ion ◽  
High Energy ◽  
Proton Spin ◽  
Relativistic Heavy Ion Collider ◽  
Spin Physics ◽  
Proton Collisions ◽  
Physics Program ◽  
Quark Spin ◽  
Polarized Proton ◽  
Spin Contribution

The STAR experiment at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory is carrying out a spin physics program in high-energy polarized proton collisions at [Formula: see text] GeV and [Formula: see text] GeV to gain a deeper insight into the spin structure and dynamics of the proton. One of the main objectives of the spin physics program at RHIC is the precise determination of the polarized gluon distribution function. The STAR detector is well suited for the reconstruction of various final states involving jets, π0, π±, e± and γ, which allows to measure several different processes. Recent results suggest a gluon spin contribution to the proton spin at the same level as the quark spin contribution itself. The production of W bosons in polarized p+p collisions at [Formula: see text] GeV opens a new era in the study of the spin-flavor structure of the proton. W-(+) bosons are produced in [Formula: see text] collisions and can be detected through their leptonic decays, [Formula: see text], where only the respective charged lepton is measured. Results of W-(+) production suggest a large asymmetry between the polarization of anti-u and anti-d quarks.

scholarly journals On Pseudorapidity Distribution and Speed of Sound in High Energy Heavy Ion Collisions Based on a New Revised Landau Hydrodynamic Model

2015 ◽  
Vol 2015 ◽  
pp. 1-23 ◽  
Author(s):  
Li-Na Gao ◽  
Fu-Hu Liu
Keyword(s):  
Speed Of Sound ◽  
Hydrodynamic Model ◽  
Quark Gluon Plasma ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
High Energy ◽  
Relativistic Heavy Ion Collider ◽  
Central Source ◽  
Ion Collisions

We propose a new revised Landau hydrodynamic model to study systematically the pseudorapidity distributions of charged particles produced in heavy ion collisions over an energy range from a few GeV to a few TeV per nucleon pair. The interacting system is divided into three sources, namely, the central, target, and projectile sources, respectively. The large central source is described by the Landau hydrodynamic model and further revised by the contributions of the small target/projectile sources. The modeling results are in agreement with the available experimental data at relativistic heavy ion collider, large hadron collider, and other energies for different centralities. The value of square speed of sound parameter in different collisions has been extracted by us from the widths of rapidity distributions. Our results show that, in heavy ion collisions at energies of the two colliders, the central source undergoes a phase transition from hadronic gas to quark-gluon plasma liquid phase; meanwhile, the target/projectile sources remain in the state of hadronic gas. The present work confirms that the quark-gluon plasma is of liquid type rather than being of a gas type.

scholarly journals Chiral Magnetic Effects in Nuclear Collisions

2020 ◽  
Vol 70 (1) ◽  
pp. 293-321 ◽  
Author(s):  
Wei Li ◽  
Gang Wang
Keyword(s):  
National Laboratory ◽  
Hadron Collider ◽  
Transport Phenomena ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
High Energy ◽  
Brookhaven National Laboratory ◽  
Relativistic Heavy Ion Collider ◽  
Nuclear Collisions ◽  
Chiral Magnetic Effect

The interplay of quantum anomalies with strong magnetic fields and vorticity in chiral systems could lead to novel transport phenomena, such as the chiral magnetic effect (CME), the chiral magnetic wave (CMW), and the chiral vortical effect (CVE). In high-energy nuclear collisions, these chiral effects may survive the expansion of a quark–gluon plasma fireball and be detected in experiments. The experimental searches for the CME, the CMW, and the CVE have aroused extensive interest over the past couple of decades. The main goal of this article is to review the latest experimental progress in the search for these novel chiral transport phenomena at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN. Future programs to help reduce uncertainties and facilitate the interpretation of the data are also discussed.

scholarly journals Recent STAR Results from Heavy-Ion and Polarized Proton Programs

2019 ◽  
Vol 222 ◽  
pp. 01004 ◽  
Author(s):  
Grigory Nigmatkulov
Keyword(s):  
Spin Asymmetry ◽  
Heavy Ion ◽  
Azimuthal Anisotropy ◽  
Relativistic Heavy Ion Collider ◽  
Longitudinal Spin ◽  
Polarized Proton ◽  
Star Experiment ◽  
Large Systems ◽  
Global And Local ◽  
Polarization Correlation

We present recent physics results from the STAR experiment at Relativistic Heavy Ion Collider (RHIC). The proceedings cover studies of azimuthal anisotropy in small and large systems, global and local hyperon polarization, correlation femtoscopy, antideuteron and J/ψ production from heavyion program as well as the measurements of longitudinal spin asymmetry from polarized proton program.

scholarly journals Comparing Standard Distribution and Its Tsallis Form of Transverse Momenta in High Energy Collisions

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Rui-Fang Si ◽  
Hui-Ling Li ◽  
Fu-Hu Liu
Keyword(s):  
Hadron Collider ◽  
Simulated Data ◽  
Heavy Ion ◽  
High Energy ◽  
Central Nucleus ◽  
Quantum Molecular Dynamics ◽  
Relativistic Heavy Ion Collider ◽  
Two Component ◽  
Standard Distribution ◽  
Effective Temperatures

The experimental (simulated) transverse momentum spectra of negatively charged pions produced at midrapidity in central nucleus-nucleus collisions at the Heavy-Ion Synchrotron (SIS), Relativistic Heavy-Ion Collider (RHIC), and Large Hadron Collider (LHC) energies obtained by different collaborations are selected by us to investigate, where a few simulated data are taken from the results of FOPI Collaboration which uses the IQMD transport code based on Quantum Molecular Dynamics. A two-component standard distribution and the Tsallis form of standard distribution are used to fit these data in the framework of a multisource thermal model. The excitation functions of main parameters in the two distributions are analyzed. In particular, the effective temperatures extracted from the two-component standard distribution and the Tsallis form of standard distribution are obtained, and the relation between the two types of effective temperatures is studied.

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