Experimental Nuclear Physics at UC Davis • FACULTY: Come visit us on the fifth floor - WEST end • Jim Draper (emeritus) • Paul Brady (emeritus) • Daniel Cebra • Ramona Vogt • GRAD STUDENTS: • Roppon Picha (2005) • Brooke Haag (2006) • UNDERGRADS: • David Cherney • STAFF: • Stephen Baumgarten • Juan Romero • Matt Searle • Tom Gutierrez • Orpheus Mall PS… Check out our web page at http://nuclear.ucdavis.edu 11-Feb-04 Daniel Cebra - Physics 295 Recent Graduates • Ian Johnson (2002) Postdoc LBNL • Jenn Klay (2001) Postdoc LBNL • Mike Heffner (2000) Postdoc LLNL • Tom Gutierrez (2000) Postdoc UCD • Bill Caskey (1999) Z-World, Davis CA • Lynn Wood (1998) Z-World, Davis CA • Doug Mayo (1997) Staff Scientist LANL • Jason Dunn (1997) Professor - Idaho Christian • Isaac Huang (1997) FunMail.com • Jack Osbourn (1995) Professor - Sac State • Jessica Kintner (1995) Professor - St. Mary’s 11-Feb-04 Daniel Cebra - Physics 295 What Do We Do? 11-Feb-04 Daniel Cebra - Physics 295 Basics Hadrons = Made of quarks Baryon = 3 q meson = q q p = uud n = udd p+ = ud K+ = us 11-Feb-04 Daniel Cebra - Physics 295 Relativistic Heavy Ion Physics: Creating Mini-`Big Bangs’ in the Laboratory 1) Goal: Use relativistic collisions of nuclear to create hot dense matter which reproduces the earliest stages of the universe 2) Now, how do we do this? (In Theory) 11-Feb-04 Daniel Cebra - Physics 295 PS… Check out our web page at http://nuclear. ucdavis.edu Brief History of the RHIC Project BRAHMS PHENIX 11-Feb-04 PHOBOS STAR Daniel Cebra - Physics 295 • • • • • • • • • • • • • 1947 BNL founded 1952 Cosmotron 1960 AGS 1970 Tandem 1979 ISABELLE 1983 CBA canceled 1983 RHIC proposed 1991 RHIC approved 1992 STAR approved 1999 First Beams 2000 First collisions 2001 200 GeV collisions 2003 d+Au collisions 1 11-Feb-04 Daniel Cebra - Physics 295 3) How do we really do this? 11-Feb-04 Daniel Cebra - Physics 295 hot partonic/nuclear matter Data sets pp Au+Au s=130 GeV NEvent=0.7 M Au+Au s=200 GeV NEvent= 3.2 M • un-polarized • vertical pol. 391/nb • longitudinal pol. 373/nb (spin flip snake) Level-3 trigger, rare probes EMC jet trigger Particle Identification: dE/dx ? resolution ~8% Au+Au s=19.6 GeV NEvent=~20k d+Au s=200 GeV NEvent=35 M 11-Feb-04 jet Daniel Cebra - Physics 295 cold partonic/nuclear matter The Relevant Questions • First, have we created ‘Matter’? •Local Kinetic Equilibrium •Bulk Properties •If so, does it have the properties of the QGP •low T, high entropy (compared to hadron gas) •opaque to jets •large fluctuations/droplets at transition •low pressure •chiral symmetry 11-Feb-04 Daniel Cebra - Physics 295 Local Thermal Equilibrium? 1 dN m A exp T thermal mT dmT T source light T heavy pT explosive source light T,b heavy ~½m<v>2 pT Fits assuming hubble-like expansion temperatures Conclusion: Thea Final freeze-out stateyields has reached a local of 90 MeV and average radial expansion velocities of 0.6c thermal equilibrium. 11-Feb-04 Daniel Cebra - Physics 295 The Hottest matter in the Universe Scientists have recently set records for both the highest and lowest measured temperatures. The high temperatures approach those of the early stage of the Big Bang. •Room Temperature 300 K •Coldest place on Earth 184 K (Vostock Station - Antarctica) •Air turns to liquid 73 K •Coldest place in the solar system (Triton) 38K •Helium turns to liquid 4.2 K •Dilution Refrigeration .002 K •Relativistic Heavy Ion Collisions 1.3x1012 K (2002) •Thermonuclear Fusion Device 3x106 K •The surface of the Sun 5800 K •The hottest place in the Solar system (Io) 2000 K •The highest recorded temperature on earth (Libya) 330 K •Magnetic Cooling 90 mK 11-Feb-04 •Ion Trapping 10 nK (1999) Daniel Cebra - Physics 295 Relativistic Heavy Ion Collider Brookhaven National Laboratory Upton, New York Is it the Right Temperature ? Tc=1603.5 MeV mb=72535 MeV e=0.3-1.3 GeV/fm3 hep-lat/0106002 Phase boundary lattice QCD: Allton et al. hep-lat/0204010 Statistical fit Result: T=176 MeV mB=41 MeV (130 GeV), T=177 MeV mB=29 MeV (200 GeV) T=2.1·1012 K Sun 15.6·106 K Supernova ~109 K Plasma fusion 55·106 K Laser fusion 4·106 K At RHIC, we see evidence that the quarks freeze-out at the expected QPG transition temperature 11-Feb-04 Daniel Cebra - Physics 295 Bulk Properties 1: Directed Flow or V1 Picture: © UrQMD X Z b Developed early - pre equilibrium ! Sensitive to the EOS As important as radial flow Well studied at lower energies Hard to be measured at RHIC because it is small XZ – the reaction plane <px> or v1 STAR Data rapidity 11-Feb-04 Daniel Cebra - Physics 295 Bulk Properties 2: Elliptic Flow or V2 Expected Hydrodynamical Behavior Profile of Source Hard Scattering dominate d region, but still showing some V2 f d 2 p d cos(2 ) dP 2 d T v2 cos 2 2 p d p d dP 2 d T p 11-Feb-04 Significant v2 up to ~7 GeV/c in pt, the region where hard scattering begins to dominate. Daniel Cebra - Physics 295 Jets at RHIC Find this……….in this p+p jet+jet (STAR@RHIC) pQCD estimate ET>1 GeV NJet~500 jet parton nucleon 11-Feb-04 nucleon Daniel Cebra - Physics 295 Au+Au ??? (STAR@RHIC) Azimuthal distributions in Au+Au Near-side: peripheral and Au+Au peripheral central Au+Au similar to p+p Au+Au central pedestal and flow subtracted Phys Rev Lett 90, 082302 Strong suppression of back-to-back correlations in central Au+Au 11-Feb-04 Daniel Cebra - Physics 295 ? Have we found the Quark Gluon Plasma at RHIC? We now know that Au+Au collisions generate a medium that • is hot => 175 MeV => the QGP transition temperature • is dense (pQCD theory: many times cold nuclear matter density) • is dissipative, jets lose energy. • exhibits strong collective behavior This represents significant progress in our understanding of strongly interacting matter We have yet to do: • Study the properties of the QGP matter • Relate these properties to the nature of the Universe (Big Bang) 11-Feb-04 Daniel Cebra - Physics 295 The ‘Bozons’ 2002 Softball Champions IM - Grad-Staff-Faculty League Daniel[outscored Cebra - Physics 295 Record: Undeated! opponents 75-21] 11-Feb-04