Download or read book Determination of Elliptic Flow and Other Properties of Charged Kaons in Relativistic Au Au Collisions Using Decay topology Identification written by John Amonett and published by . This book was released on 2008 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the beginning, there was quark gluon plasma (QGP). QGP persisted for only on the order of microseconds after the Big Bang. This exotic state of matter consists of deconfined quarks and gluons under extreme conditions. It is believed that the QGP state can be recreated in the laboratory through heavy-ion collisions at ultra-high energies. The Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory appears to produce sufficiently high energy to exceed the threshold for creating the QGP phase. There are four experiments at RHIC, and one of the largest is the Solenoidal Tracker at RHIC (STAR). The STAR detector utilizes a Time Projection Chamber with full azimuthal acceptance to track as many as thousands of produced particles from a single nucleus-nucleus collision. The QGP state of matter has many proposed signatures. This project explores the anisotropic elliptic flow properties of gold (Au) on gold collisions. Elliptic flow corresponds to the second harmonic coefficient (v2) of a Fourier decomposition of the transverse momentum distribution of emitted particles. Elliptic flow is the dominant term in the quantitative description of the collective motion among the particles produced in this type of heavy-ion collision. The focus of this dissertation is on a single type of particle, the charged kaon (K"). Charged kaons are the least massive particles that contain strange quarks. Using conventional techniques based on rate of energy loss, identification of charged kaons becomes difficult above a momentum of ~ 600 MeV/c. This project uses a topological method to identify decaying charged kaons up to transverse momenta ~ 4 GeV/c. Our topological method has the drawback of relatively low efficiency, which decreases with increasing momentum. The data set studied in this dissertation corresponds to gold on gold interactions at the maximum energy of the RHIC machine, and collisions across the full range of impact parameters are analyzed. Possible charged kaons are tagged from a list of candidates. The viable charged kaons are chosen using a series of stringent identification criteria. The reaction plane is determined for each event, and elliptic flow is calculated, correcting for the systematic effects caused by the finite reaction plane resolution. The dependence of elliptic flow on transverse momentum is highly significant when different particle types can be compared. The data for charged kaons falls into a pattern where there is a universal curve for the amount of flow per constituent quark as a function of the quark's transverse momentum. This universal curve can account for the flow observed for all known particle types. It suggests that the collective motion must have been imparted during the early phase of the collision when a QGP state existed. A different pattern would be expected if the collective motion had been imparted after the quarks had coalesced into hadrons, or if the QGP state had not been formed at all. The dissertation discusses the significance of the new evidence, and the caveats and possible alternative explanations.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 868 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Elliptic Flow in Au Au Collisions at 200 GeV Per Nucleon Pair written by Carla Manuel Vale and published by . This book was released on 2004 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Relativistic Heavy Ion Collider (RHIC) has provided its experiments with the most energetic nucleus-nucleus collisions ever achieved in a laboratory. These collisions allow for the study of the properties of nuclear matter at very high temperature and energy density, and may uncover new forms of matter created under such conditions. This thesis presents measurements of the elliptic flow amplitude, v2, in Au+Au collisions at RHIC's top center of mass energy of 200 GeV per nucleon pair. Elliptic flow is interesting as a probe of the dynamical evolution of the system formed in the collision. The elliptic flow dependences on transverse momentum, centrality, and pseudorapidity were measured using data collected by the PHOBOS detector during the 2001 RHIC run. The reaction plane of the collision was determined using the multiplicity detector, and the azimuthal angles of tracks reconstructed in the spectrometer were then correlated with the found reaction plane. The v2 values grow almost linearly with transverse momentum, up to P[sub]T of approximately 1.5 GeV, saturating at about 14%. As a function of centrality, v2 is minimum for central events, as expected from geometry, and increases up to near 7% (for 0

Download or read book Measurement of Non flow Correlations and Elliptic Flow Fluctuations in Au Au Collisions at Relativistic Heavy Ion Collider written by Burak Han Alver and published by . This book was released on 2010 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of collective flow and two-particle correlations have proven to be effective tools for understanding the properties of the system produced in ultrarelativistic nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC). Accurate modeling of the initial conditions of a heavy ion collision is crucial in the interpretation of these results. The anisotropic shape of the initial geometry of heavy ion collisions with finite impact parameter leads to an anisotropic particle production in the azimuthal direction through collective flow of the produced medium. In "head-on" collisions of Copper nuclei at ultrarelativistic energies, the magnitude of this "elliptic flow" has been observed to be significantly large. This is understood to be due to fluctuations in the initial geometry which leads to a significant anisotropy even for most central Cu+Cu collisions. This thesis presents a phenomenological study of the effect of initial geometry fluctuations on two-particle correlations and an experimental measurement of the magnitude of elliptic flow fluctuations which is predicted to be large if initial geometry fluctuations are present. Two-particle correlation measurements in Au+Au collisions at the top RHIC energies have shown that after correction for contributions from elliptic flow, strong azimuthal correlation signals are present at A0 = 0 and A0 ~ 120. These correlation structures may be understood in terms of event-by-event fluctuations which result in a triangular anisotropy in the initial collision geometry of heavy ion collisions, which in turn leads to a triangular anisotropy in particle production. It is observed that similar correlation structures are observed in A Multi-Phase Transport (AMPT) model and are, indeed, found to be driven by the triangular anisotropy in the initial collision geometry. Therefore "triangular flow" may be the appropriate description of these correlation structures in data. The measurement of elliptic flow fluctuations is complicated by the contributions of statistical fluctuations and other two-particle correlations (non-flow correlations) to the observed fluctuations in azimuthal particle anisotropy. New experimental techniques, which crucially rely on the uniquely large coverage of the PHOBOS detector at RHIC, are developed to quantify and correct for these contributions. Relative elliptic flow fluctuations of approximately 30-40% are observed in 6-45% most central Au+Au collisions at s NN= 200 GeV. These results are consistent with the predicted initial geometry fluctuations.

Download or read book Elliptic Flow in AU AU Collisions at SNN written by Aihong Tang and published by . This book was released on 2002 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Momentum integrated Elliptic Flow and Transverse Collision Geometry in Ultrarelativistic Nucleus nucleus Collisions written by Peter Kirk Walters and published by . This book was released on 2013 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Ultrareletivistic nuclear collisions at the Relativistic Heavy-Ion Collider have produced a high temperature, high energy density medium consisting of a strongly interacting plasma of quarks and gluons. This extreme state of matter provides a testing ground for quantum chromodynamics. Previous studies of gold-gold collisions over a wide range of beam energies revealed many properties of the produced medium. However, these studies were restricted to relatively large colliding systems which resulted in large collision volumes; it is therefore important to investigate what role the size of the collision volume plays in the evolution of the source, particularly as the source volume becomes vanishingly small. This can be achieved with symmetric copper-copper collisions, which offer access to a range of system sizes from [approximately] 10 participating nucleons up through volumes comparable to those created in gold-gold collisions. Collective behaviors of the produced particles in heavy-ion collisions can provide useful probes into the state of the medium produced, including its degree of thermalization and its properties. The elliptic flow, an anisotropy in the azimuthal distribution of the produced particles that is strongly correlated to the initial transverse geometry of the colliding nuclei, is one such collective motion that has proven to be a very useful observable for studying heavy-ion collisions. This is because it exhibits fairly large magnitudes in the systems being studied and is sensitive to the strength of the partonic interactions in-medium. The PHOBOS experiment, which can measure the positions of produced charged particles with high precision over nearly the full solid angle, is well-suited to study the elliptic flow and its evolution over an extended range along the beam direction. The elliptic flow from copper-copper collisions at center-of-mass energies of 22.4, 62.4, and 200GeV per nucleon pair are presented as a function of pseudorapidity and system size. The appearance of unexpected behaviors in the smaller system prompted a re-examination of the role of the collision geometry on the production of elliptic flow. Studies using Monte-Carlo Glauber simulations found that the fluctuating spatial configurations of the component nucleons in the colliding nuclei could result in significant variation of the shape of the nuclear overlap on an event-by-event basis, and that these fluctuations become important for small systems. The eccentricity, a quantity that characterizes the ellipticity of the nuclear overlap in the transverse plane, is redefined to account for these fluctuations as the participant eccentricity. It is found that the event-by-event fluctuations of the participant eccentricity are able to fully account for the observed elliptic flow in the smaller system. The participant eccentricity is used to normalize the measured elliptic flow across different colliding systems to a common initial geometry so that a direct comparison of the properties of the produced medium can be made. It is found that the produced medium evolves smoothly from systems of [approximately] 10 participant nucleons to systems involving more than 350 nucleons and for collision energies from 19.6 to 200GeV per nucleon pair. This smooth evolution of the elliptic flow is also observed as a function of pseudorapidity in all the systems studied. After accounting for the initial geometry, no indication of the identity of the original colliding system is observed"--Page vi-vii.

Download or read book Effects of Mean field and Softening of Equation of State on Elliptic Flow in Au Au Collisions at SNN written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: We perform a systematic study of elliptic flow ( v 2 ) in Au+Au collisions at s NN = 5 GeV by using a microscopic transport model, JAM. The centrality, pseudorapidity, transverse momentum and beam energy dependence of v 2 for charged as well as identified hadrons are studied. We investigate the effects of both the hadronic mean-field and the softening of equation of state (EoS) on elliptic flow. The softening of the EoS is realized by imposing attractive orbits in two body scattering, which can reduce the pressure of the system. We found that the softening of the EoS leads to the enhancement of v 2, while the hadronic mean-field suppresses v 2 relative to the cascade mode. It indicates that elliptic flow at high baryon density regions is highly sensitive to the EoS and the enhancement of v 2 may probe the signature of a first-order phase transition in heavy-ion collisions at beam energies of a strong baryon stopping region.

Download or read book Charged and Strange Hadron Elliptic Flow in Cu Cu Collisions at Sqrt SNN written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the results of an elliptic flow, v2, analysis of Cu+Cu collisions recorded with the STAR detector at RHIC at √s{sub NN} = 62.4 and 200 GeV. Elliptic flow as a function of transverse momentum, v2(p{sub T}), is reported for different collision centralities for charged hadrons h{sup {+-}}, and strangeness containing hadrons K{sub S}°, [Lambda], [Xi], [phi] in the midrapidity region.

Download or read book First Moment of Azimuthal Anisotropy in Au Au Collisions from the Beam Energy Scan at the Relativistic Heavy Ion Collider written by Prashanth Shanmuganathan and published by . This book was released on 2016 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excited nuclear matter at high temperature and density results in the creation of a new state of matter called Quark Gluon Plasma (QGP). It is believed that the Universe was in the QGP state a few millionths of a second after the Big Bang. A QGP can be experimentally created for a very brief time by colliding heavy nuclei, such as gold, at ultra-relativistic energies. The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory consists of two circular rings, 3.8 km in circumference, which can accelerate heavy nuclei in two counter-rotating beams to nearly the speed of light (up to 100 GeV per beam). STAR (Solenoidal Tracker At RHIC) is one of two large detectors at the RHIC facility, and was constructed and is operated by a large international collaboration made up of more than 500 scientists from 56 institutions in 12 countries. STAR has been taking data from heavy ion collisions since the year 2000. An important component of the physics effort of the STAR collaboration is the Beam Energy Scan (BES), designed to study the properties of the Quantum Chromodynamics (QCD) phase diagram in the regions where a first-order phase transition and a critical point may exist. Phase-I of the BES program took data in 2010, 2011 and 2014, using Au+Au collisions at a center-of-mass energy per nucleon pair of 7.7, 11.5, 14.5, 19.6, 27 and 39 GeV. It is by now considered a well-established fact that the QGP phase exists. However, all evidence so far indicates that there is a smooth crossover when normal hadronic matter becomes QGP and vice versa in collisions at the top energy of RHIC (and likewise at the Large Hadron Collider at the CERN laboratory in Switzerland). At these very high energies, the net density of baryons like nucleons is quite low, since there are almost equal abundances of baryons and antibaryons. It is known that net-baryon compression increases as the beam energy is lowered below a few tens of GeV. Of course, if the beam energy is too low, then the QGP phase cannot be produced at all, so it has been proposed that there is an optimum beam energy, so far unknown, where phenomena like a first-order phase transition and a critical point might be observed. On the other hand, there also exists the possibility that a smooth crossover to QGP occurs throughout the applicable region of the QCD phase diagram. Experiments are needed to resolve these questions. In this dissertation, I focus on one of the main goals of the BES program, which is to search for a possible first-order phase transition from hadronic matter to QGP and back again, using measurements of azimuthal anisotropy. The momentum-space azimuthal anisotropy of the final-state particles from collisions can be expressed in Fourier harmonics. The first harmonic coefficient is called directed flow, and reflects the strength of the collective sideward motion, relative to the beam direction, of the particles. Models tell us that directed flow is imparted during the very early stage of a collision and is not much altered during subsequent stages of the collision. Thus directed flow can provide information about the early stages when the QGP phase exists for a short time. A subset of hydrodynamic and nuclear transport model calculations with the assumption of a first-order phase transition show a prominent dip in the directed flow versus beam energy. I present directed flow and its slope with respect to rapidity, for identified particle types, namely lambda, anti-lambda and kaons as a function of beam energy for central, intermediate and peripheral collisions. The production threshold of neutral strange particles requires them to be created earlier, and these particles have relatively long mean free path. Thus these particles may probe the QGP at earlier times. In addition, new Lambda measurements can provide more insight about baryon number transported to the midrapidity region by stopping process of the nuclear collision. It is noteworthy that net-baryon density (equivalent to baryon chemical potential) depends not only on beam energy but also on collision centrality. The centrality dependence of directed flow and its slope are also studied for all BES energies for nine identified particle types, lambda, anti-lambda, neutral kaons, charged kaons, protons, anti-protons, and charged pions. These detailed results for many particle species, where both centrality and beam energy are varied over a wide range, strongly constrain models. The measurements summarized above pave the way for a new round of model refinements and subsequent comparisons with data. If the latter does not lead to a clear conclusion, the BES Phase-II program will take data in 2019 and 2020 with an upgraded STAR detector with wider acceptance, greatly improved statistics, and will extend measurements to new energy points.

Download or read book Measurements of Elliptic Flow in Ultra relativistic Heavy Ion Collisions written by Rachel Yin Ching Mak and published by . This book was released on 2005 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Directed and Elliptic Flow in Au Au Collisions at a Center of Mass Energy of 19 6 GeV Per Nucleon nucleon Pair written by Michael George Anderson and published by . This book was released on 2006 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book D0 Meson Elliptic Triangular Flows And Event Shape Engineering Study In Au Au Collisions At square Root S subscript NN written by Yue Liang and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heavy ion collisions at Relativistic Heavy Ion Collider (RHIC) provide a unique environment to probe nuclear matter under extremely high temperature and density conditions. Among the many insights that can be provided are studying the Quark Gluon Plasma (QGP) created in these collisions, the interaction of color-charged probes with the QGP, the mechanism of hadronization as well as the nature of phase transition to the deconfined phase. Production of heavy quarks in high-energy nuclear collisions occurs mainly through initial hard scattering, via gluon fusion and quark anti-quark annihilation, since the thermal production in the hot QCD medium is significantly suppressed due to the heavy quark masses. This makes heavy quarks ideal probes of the QGP as they experience the whole medium evolution. The diffusion of a heavy particle through a heat bath of the hot-QCD medium can be quantified by the spatial diffusion coefficient D[subscript]s, in analogy to the Brownian motion in molecular physics. Early calculations based on perturbative methods for the diffusion coefficient for the charm and bottom quarks in a QGP produced values of D[subscript]s(2[pi]T) ~ 30 ~ O(1/[alpha]2[subscript]s) for a strong coupling constant of [alpha][subscript]s ~ 0.3-0.4 and with a value varying only weakly with temperature. We now know that these values for D[subscript]s are too large to account for the open heavy-flavor (HF) observables, including the elliptic flow (v2) of D0 mesons, in heavy-ion collisions at RHIC and the LHC. New measurements, including of higher order flow, with better precision and studying their dependence on collision geometry and size and shape of the produced medium allow us to better constrain the value of D[subscript]s and the heavy quark interaction with the QGP. The Solenoidal Tracker At RHIC (STAR) experiment is one of the two remaining large detector systems at the RHIC. The Time Projection Chamber (TPC) is the main detector at STAR measuring 4.2 m in length and 4 m in diameter, it provides full azimuthal coverage out to ± 1.0 units of rapidity and particle identification down to transverse momenta of 100 MeV/c. The Heavy Flavor Tracker (HFT) silicon vertex upgrade for the STAR experiment, is utilizing active pixel sensors and silicon strip technology and provides excellent track pointing resolution to allow the reconstruction of heavy flavor hadron decays. My thesis work is utilizing the STAR Heavy Flavor Tracker's combined datasets recorded during RHIC 2014 and 2016 runs to measure with improved precision the D0-meson elliptical (v2) and triangular flow (v3) as a function of event centrality (quantity which describes the overlap region between the two colliding nuclei) and D0 transverse momentum. I also present results obtained with a new method of event-shape-engineering (ESE) to study correlations of D0 v2 with the event geometry. The physics results are compared with model simulations. My results confirm that the D0 v2 follows the same number-of-constituent-quark (NCQ) scaling as light flavor hadrons. Non-zero v3 is observed, and by combining the 2014 and 2016 data, I also observe that the v3 also follows the NCQ scaling as light hadrons. Compared to theoretical model calculations, the observed large v2/v3 results demonstrate that charm quarks gain these strong collectivity through the diffusion in the strongly-coupled QGP medium. From the ESE study, I observe that the event-shape q2 dependence of the measured [pi][superscript]±, K[superscript]± and D0 hadrons follow the similar linear dependence with comparable slope in 10-40% Au+Au collisions. This demonstrated that the heavy flavor hadron v2 is driven by the event geometry. These results allow putting strict constraints on the values of the diffusion coefficient D[subscript]s. STAR's v2 results have been included in recent model analyses and provided a constraint on the 2[pi]TD[subscript]s to be around 2-5 near the T[subscript]c region while the temperature dependence from various models remains largely uncertain. The next phase of heavy flavor programs at RHIC and LHC need to focus on better constraining the temperature/momentum dependence on the heavy quark diffusion coefficient. Furthermore, since the bottom quark mass is much larger than that of charm, theoretically, bottom quark transport in QGP medium can be better described by the Langevin simulation. Testing the universality of heavy quark spatial diffusion coefficient between charm and bottom quarks will be also the next focus in RHIC and LHC HF programs.

Download or read book Elliptic Flow in Au Au Collisions at 11 5 A GeV c written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Strongly Interacting Matter in Magnetic Fields written by Dmitri Kharzeev and published by Springer. This book was released on 2014-07-08 with total page 630 pages. Available in PDF, EPUB and Kindle. Book excerpt: The physics of strongly interacting matter in an external magnetic field is presently emerging as a topic of great cross-disciplinary interest for particle, nuclear, astro- and condensed matter physicists. It is known that strong magnetic fields are created in heavy ion collisions, an insight that has made it possible to study a variety of surprising and intriguing phenomena that emerge from the interplay of quantum anomalies, the topology of non-Abelian gauge fields, and the magnetic field. In particular, the non-trivial topological configurations of the gluon field induce a non-dissipative electric current in the presence of a magnetic field. These phenomena have led to an extended formulation of relativistic hydrodynamics, called chiral magnetohydrodynamics. Hitherto unexpected applications in condensed matter physics include graphene and topological insulators. Other fields of application include astrophysics, where strong magnetic fields exist in magnetars and pulsars. Last but not least, an important new theoretical tool that will be revisited and which made much of the progress surveyed in this book possible is the holographic principle - the correspondence between quantum field theory and gravity in extra dimensions. Edited and authored by the pioneers and leading experts in this newly emerging field, this book offers a valuable resource for a broad community of physicists and graduate students.

Download or read book Pseudorapidity Dependence of Directed and Elliptic Flow in Au Au Collisions at 19 6 62 4 130 and 200 GeV Per Nucleon Pair written by Joshua Brian Hamblen and published by . This book was released on 2006 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heavy quark Production and Elliptic Flow in Au Au Collisions at u221A sNN written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, we present measurements of electrons and positrons from the semileptonic decays of heavy-flavor hadrons at midrapidity (

Download or read book Properties of Charged particle Production at Mid rapidity for Au Au Collisions at RHIC Energies written by Aneta Iordanova and published by . This book was released on 2005 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: