1. Daniel Cebra - Physics 295 Seminar 29-Jan-02 The UCD Nuclear Physics Group Daniel Cebra Goal of this talk - to introduce the nuclear physics group and explain what we do and why it is interesting PS… Check out our web page at http://nuclear.ucdavis.edu

2. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Meet the Group FACULTY: Jim Draper (emeritus) Paul Brady (emeritus) Daniel Cebra Ramona Vogt Daniel Ferenc STAFF: Juan Romero Tom Gutierrez GRAD STUDENTS: Mike Anderson (2002) Ian Johnson (2002) Steve Oliver (2004) Roppon Picha (2005) UNDERGRADS: Mark Allen Trieu Mai Daniel Clayton Stephen Baumgarten Come visit us on the fifth floor - WEST end

3. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Recent Graduates 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 Jerry Chance (1997) Postdoc LBNL 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

4. Daniel Cebra - Physics 295 Seminar 29-Jan-02 What Do We Do?

5. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Abstract of Research Goals The study of collisions between relativistic nuclei will ultimately allow the determination of the properties of nuclear matter over a wide range of temperatures and densities. Without the possibility of direct studies of nuclear matter in bulk (as in neutron stars, supernovae, or the Big Bang), one resorts to the challenging studies of finite and transient systems as provided by nucleus- nucleus collisions. Our experiments search for signatures of the Quark Gluon Plasma (QGP), a phase of matter which dominated the early stages of the Big Bang.

6. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Basics Hadrons = Made of quarks Baryon = 3 q meson = q q p = uud n = udd  + = ud K+ = us

7. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Goals of Relativistic Heavy Ions To study the properties of nuclear matter. Specifically to study the Quark- gluon plasma Allows a better understanding of the earliest phase of the universe.

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9. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Nuclear Matter Phase Diagram Baryon Density Temperature

10. Daniel Cebra - Physics 295 Seminar 29-Jan-02 The Start of RHIC - Summer 00

11. Daniel Cebra - Physics 295 Seminar1 29-Jan-02 Brief History of the RHIC Project 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 Full Energy

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13. Daniel Cebra - Physics 295 Seminar 29-Jan-02 The STAR Experiment - Plans

14. Daniel Cebra - Physics 295 Seminar 29-Jan-02 STAR - Under Construction

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16. Daniel Cebra - Physics 295 Seminar 29-Jan-02 The Detector Now...

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19. Daniel Cebra - Physics 295 Seminar 29-Jan-02 The FIRST Event!

20. Daniel Cebra - Physics 295 Seminar 29-Jan-02 STAR - peripheral event - Front Tracks emerge from common vertex point Grazing collisions produce few tracks Magnetic field bends trajectories into helices - allows measure of momentum Particle ID through gas dE/dx

21. Daniel Cebra - Physics 295 Seminar 29-Jan-02 STAR - peripheral event - side Determines the z location of the vertex emission angles of the tracks. Demonstrate true 3D tracking

22. Daniel Cebra - Physics 295 Seminar 29-Jan-02 STAR Event - Front View Central events have much higher multiplicity of tracks. Up to 2000 charged particles in the TPC’s accpectance

23. Daniel Cebra - Physics 295 Seminar 29-Jan-02 STAR Event -- Side View

24. Daniel Cebra - Physics 295 Seminar 29-Jan-02 STAR Calibration and Analysis Spatial resolution 700  Tracking - better then 90% efficiency dE/dx resolution = 8% momentum resolution better than 1%  K p e

25. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Spectra Temperatures are measured in the range expected for a QGP transition Suggestive result, but further analysis is needed

26. Daniel Cebra - Physics 295 Seminar 29-Jan-02 How we “see” Strangeness See Strange Hadrons –kaon (u or d and s) –lambda (uds) –Omega (sss) –etc... Distinguishing Decay Topologies –V0 –kink V0 vertex kink

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28. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Centrality: Participants vs. Spectators “Spectators” Zero-degree Calorimeter “Spectators” Many things scale with N part : Transverse Energy Particle Multiplicity Particle Spectra “Participants” Only ZDCs measure N part The collision geometry (i.e. the impact parameter) determines the number of nucleons that participate in the collision Produced Particles

29. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Z ero D egree C alo as centrality device Only shared detector – –Rates: luminosity via well-known reference process – –Timing: substantial background rejection – –Pulse height: measures centrality Directly confirms monotonic relationship between participants with multiplicity

30. Daniel Cebra - Physics 295 Seminar 29-Jan-02 d  /dN vs N Comparison to cascade models demonstrates to collective behavior of nuclear systems Used to determine centrality of collisions

31. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Shapes of dN ch /d  for different N part   dN ch /d  (dN ch /d  )/(½N part ) dN ch /d  Data HIJING (dN ch /d  )/(½N part ) 354 216 102 Mean N part %% 0-3 15-20 35-40 Data

32. Daniel Cebra - Physics 295 Seminar 29-Jan-02 dN/d  Higher multiplicity than comparable p+p collisions indicates collective nature. Impressive agreement between the exps STAR PHENIX BRAHMS

33. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Source Radii The expected expansion of the outward radius is not seen. Transition may be at lower energy or more subtle. PHENIX

34. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Hydrodynamic Flow - Defined Radial flow – –Not seen in angular distributions – –Use HBT, spectra (T = T o + m Directed flow – –Forward rapidities – –Not measured yet PHOBOS/STAR – –Interesting predictions for phase transition… Elliptic flow – –Early time push, hydrodynamic evolution – –Strongest at y=0

35. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Hydrodynamic Flow - Results The RQMD cascade can not account for the observed flow. Collective behavior is demonstrated.

36. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Hydrodynamic Flow - Results Hydrodynamic model V2V2 Centrality midrapidity : |h| < 1.0 SPS AGS Preliminary RQMD

37. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Conclusions ‘00 and ‘01 Heavy-ion running was successful - physics results already. But the QGP question is not yet resolved. ‘02 polarized proton+proton running. Detectors Continue to improve (5-10 years). Future: eRHIC Future: LHC

38. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Compact Muon Solenoid

39. Daniel Cebra - Physics 295 Seminar 29-Jan-02 APS - join Now All active physicists should join APS Students memberships a very reasonable Go to meetings, give talks! California Section - next meeting will be in Davis

40. Daniel Cebra - Physics 295 Seminar 29-Jan-02 Intramural Sports! Basketball Basketball Soccer Soccer Softball Softball Other sports? Other sports?