Elliptic Flow Of Hadrons As A Probe For Locating The QCD Critical Point And Drawing The Phase Boundary And Determining The Extreme UU Collisions

For thousands of years, the curiosity of mankind drive us to ask the same ques-tion:what and how forms our world? Now, the standpoint is that quarks and gluons build up the world of matter. And Quantum ChromoDynamics (QCD) established in 1970s is believed to be a very successful theory to describe the strong force be-tween the quarks and gluons with color charge carriers. QCD has two basal features asymptotic freedom and quarks confinement, which lead to the fact quarks and gluons are confined in hadrons and no free quarks and gluons are observed.There are two ways by compressing/heating the hadrons system to increase the the matter density/temperature to smash the bag of hadrons. Lattice QCD predicts the phase transition at high temperature or high density from the normal hadron gas state to a partonic state with deconfined hadrons--quarks and gluons, which are named as the Quark Gluon Plasma (QGP). And the farther calculation indicates the phase transition will occur at the critical temperature Tc～160MeV or 10 time the density of normal matter.QGP maybe exit in the early universe in the first few seconds after the Big Bang or the neutron star, but can't be measured directly as a result of too early and too far to us. In the 1970s of last century, T.D. Lee et al. predicted that through high energy heavy ion collisions it is possible to form a high energy and/or high density environment in space so that a new state of matter - quark gluon plasma consisting of a large amount of deconfined quarks, antiquarks and gluons will be produced. One of the goal to perform the heavy ion collision in the laboratory is to create and study the property of the partonic matter with high temperature and/or high density. In so extreme cases, QGP maybe appear.The Relativistic Heavy Ion Collider (RHIC) located at Brookhaven National Laboratory (BNL) was designed to collide high energy heavy ions to create such a high temperature and high density matter and to search for Quark-Gluon Plasma (QGP) and study its properties. After several years of measurements accumulation, the matter created RHIC has been proved to be more like a medium most resemble of properties of a perfect liquid of strongly interacting quark gluon plasma. One of the pillars for this discovery are the observed strong elliptic flow of partonic matter. From the data in RHIC top energy (?)200GeV AuAu collisions, the second harmonic azimuthal anisotropy, elliptic flowν2 of identified particles established hydro-like mass hierarchy at low pr, which demonstrates the development of partonic collectivity. Further, the Number-of-Constituent-Quark (NCQ) scaling observed at intermediate pT suggest that the system has been in the deconfined state prior to hadronization. On the other hand, charged particle v2 scaled by the eccentricity suggests possible thermalization only in the most central collisions at top RHIC energy.An effective ways to verify whether or not the medium is thermalized is using UU instead of AuAu collisions. Theoretical calculations show that the energy density in (?)= 200GeV central UU collisions will exceed 30% than AuAu collisions. This hints that some visible sign about the thermalization of medium may be seen in central UU collisions. Some plans about UU collisions, (?)= 200GeV UU collision in RHIC, Eb= 30AGeV in GSI/SIS300 and Eb/A=0.52GeV in HIFRL-CSR, will be perfomed in the further.238U is the most deformed (δ≈0.27) stable nucleus. As a homogeneous e1-lipsoid, the ratio of the long-axis over short-axis is as large as 1.3. As a result of the deformation, UU collisions at the same beam energy and impact parameter but different orientations are expected to form dense matter with different compressions and lifetimes. It is expected that the tip-tip collisions can form a higher densities of nuclear matter with longer duration than body-body or the spherical nuclei collisions and easier to reach thermal equilibrium.For the non-polarized UU collision, target and projectile have random orienta-tions in the initial coordinate space. Ideal tip-tip and body-body events are quite unusual. So, how to select the central tip-tip like events in experiment is the key to perform UU collisions.In this paper,we have test and developed two measurements allowing us to se-lect those high-density events in CSR. The forward neutron multiplicity and nuclear stopping power are suitable for fast on-line and off-line physics analysis, respectively. We also expect these results is useful for performing UU collisions in RHIC and GSI in the further.The newest QCD phase diagram predicted by lattice gauge theory(LGT) is the following:in the region with high baryon chemical potential and low temperature the transition between normal hadronic matter and QGP is a first order phase transition. As the increase of temperature and decrease of baryon chemical potential, the first order phase-transition line ends at the critical point and at even higher temperature and lower baryon chemical potential, there is a crossover. It is estimated that at the RHIC and the coming LHC energy regions, a high temperature and low baryon chemical potential environment will be created, and thus falls in the crossover region.For studying QCD phase diagram, RHIC/STAR beam energy scan(BES) pro-gram focus on drawing the QCD phase boundary and locating the critical point(CP). The range of beam energy is (?)=5～30GeV. At the critical point of phase transition, there should be some observables undergoing dramatic change. There are two candidates as the signs for this search, the fluctuation of net-baryon multiplicity and the elliptical flow of hardons. This paper only focus on the latter. The NCQ scaling of hardons v2 in RHIC is a particular feature about the medium with partonic freedom degree. So, if the interactions only occur on hardons, this NQ scaling will be broken.By employing the AMPT model, it's clearly seen that the NCQ scaling will be preserved in a partonic phase scenario (string melting) while be broken in a hadronic phase scenario (default version). The possible deviation of the NCQ scaling for identified particles may signal a transition from partonic phase to hadronic phase.More specially, due to OZI rule,Φmesons can only be formed via the coalescence of strange quarks. In the hadronic environment of hadronic interactions, there is no partonic collectivity, in addition to the lack of quark-scaling, the value of v2 of theΦmesons must be close to zero or very small.More predict the property of critical point and the phase boundary is worth further study.