Relativistic Nuclear Collisions (RNC) Group Nuclear Science Division (NSD), Lawrence Berkeley National Lab The Relativistic Nuclear Collisions (RNC) group is the experimental high energy nuclear physics group in Nuclear Science Division at LBNL. The focus of the RNC experimental physics program is the exploration of QCD matter under extreme conditions, and of the fundamental structure of nucleons and nuclei through high energy collisions of (polarized) protons and nuclei. RNC plays leading roles in the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory and the ALICE experiment at the Large Hadron Collider (LHC) at CERN. RNC is a physics leader in both experiments and has contributed major equipment and upgrades. RNC is an international group of more than 25 scientists, about half of them students and postdocs. A small group is stationed at the location of both of our experiments, at CERN and at BNL. Spin physics program at RHIC The goal is to experimentally determine the structure of the proton spin by observing small spin-dependent effects in the collisions of polarized protons. RHIC offers a unique opportunity to study the collisions of two polarized proton beams at the energies s = 200 and 500 GeV. Proton spin budget Total spin is a sum of spins and orbital angular momenta of quarks and gluons Data analysis at STAR Gluon polarization G At present, the spin of low-momentum gluons is not well known, and STAR measurements are competitive among other world data. Gluon polarization is measured by observing the spin dependence of the production cross sections of jets, jet pairs, and pions. Quark polarization Only 30% of the nucleon spin is well measured today ( 0.3), and its distribution among quark flavors is not well known. STAR uses large acceptance detectors to measure some flavors of quarks and anti-quarks. Spin of u and d quarks is accessed by measuring the W boson production. Spin of s quarks is probed by observing the spin transfer from proton to hyperons. Transverse spin phenomena Effects that depend on the transverse spin structure of the proton are studied with the transversely polarized proton beams at RHIC. In this area of research, STAR measures the production of 0 and mesons and neutrons in the forward direction. Inner Micro-Vertex Detector Project Contact information: MS70R0319, Lawrence Berkeley National Lab One Cyclotron Road, Berkeley, Tel: Fax: Web:Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab The Relativistic Heavy Ion Collider (RHIC) locates at Brookhaven National Lab (BNL) at Long Island, NY. RHIC is the first machine in the world capable of colliding heavy ions and polarized protons (see the Spin section). The beams travel at nearly speed of light in opposite directions around RHIC's 2.4-mile, two-lane "racetrack." At six intersections, the lanes cross, leading to an intersection. RHIC collisions occur thousands of times per second. Each one acts as a microscopic pressure cooker, producing temperatures and pressures more extreme than exist now even in the cores of the hottest stars. Temperature inside a RHIC collision can be many thousand times the temperature of the sun. Relativistic heavy ion collisions provide us an effective tool to study the creation and characteristics of such a matter in laboratory. During the collision, tremendous amount of energy are dumped into a small volume to achieve sufficient energy density. Just after the collision, thousands more particles form as the area cools off. Each of these particles provides a clue as to what occurred inside the collision zone. The Solenoidal Tracker At RHIC (STAR) detector is a specially designed detector to track thousands of particles simultaneously created in heavy ion collisions. Protons and neutrons are made up of three quarks, along with the gluons that bind them together. Theory predicts at sufficient high temperature and density, quarks and gluons can be liberated and form a new state of matter - Quark Gluon Plasma (QGP). Theory also holds that for a brief time at the beginning of the universe there were no protons and neutrons, only free quarks and gluons. A state of the art, high resolution vertex detector is being built for installation in the STAR experiment at RHIC. The purpose of this device is to identify D and B mesons created in the collisions of 200 GeV Au on Au collisions at RHIC, and thus provide a measure of heavy quark yields in these reactions. The D and B mesons are short lived and travel a short distance ( a few 10s of microns) from the collision point before decaying into secondary particles. The vertex detector with two layers of silicon pixel chips a few centimeters from the interaction point has position resolution sufficient to distinguish these relatively rare secondary tracks from the thousands of other tracks emanating from the collisions point thus allowing identification and measurement of D and B meson yields. Accomplishing the required track pointing resolution is an engineering challenge. The silicon detector with its support structures must be very thin, the silicon is 50 microns thick, to reduce multiple coulomb scattering. At the same time the detector must be mechanically quite stable to maintain good position resolution. The detectors, key to this device, are monolithic silicon mega pixel chips with 20 micron square pixels. Large Hadron Collider (LHC) The LHC (Large Hadron Collider) is a 27km circumference synchrotron accelerator on the border of Switzerland and France. ALICE (A Large Ion Collider Experiment ) is a collaboration of about 1000 physicists from 33 countries and 115 institutions. ALICE is the dedicated heavy ion experiment at the LHC, optimized for comprehensive measurements of the very complex final state generated in high energy nuclear collisions. ALICE can track precisely many thousands of particles in each event, measuring jets, photons, heavy flavor mesons and baryons, and quarkonia. The emphasis of the ALICE LBNL group is the study of jet quenching, which we pioneered in STAR at RHIC and which will be central to the LHC heavy ion program. There is broad theoretical interest in such measurements, aspects of which may even be calculable in string theory. The RNC effort in STAR dates back to the inception of the experiment in 1990 and concerns research with collisions of heavy ion beams over a wide range in center-of-mass energies, ranging from s NN = 7.7 GeV to 200 GeV, which enables us to study properties of new partonic matter at top energy as well as search for phase transition signatures.