1 / 45

The UCD Nuclear Physics Group

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. Meet the Group. GRAD STUDENTS: Mike Anderson ( 2001 )

tim
Download Presentation

The UCD Nuclear Physics Group

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 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 Daniel Cebra - Physics 295 Seminar

  2. Meet the Group • GRAD STUDENTS: • Mike Anderson (2001) • Jenn Klay (2001) • Ian Johnson (2002) • Agusta Loftsdottir • Clay Bratton • UNDERGRADS: • Stephenie Ritchey • Mark Allen • Allen Thoe • Stephen Baumgarten • FACULTY: • Jim Draper (emeritus) • Paul Brady • Daniel Cebra • Ramona Vogt • Daniel Ferenc • STAFF: • Juan Romero • Tom Gutierrez Come visit us on thefifth floor - WEST end Daniel Cebra - Physics 295 Seminar

  3. Recent Graduates • 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 Daniel Cebra - Physics 295 Seminar

  4. What Do We Do? Condensed Matter High Energy Relativistic Heavy Ion Physics Cosmology Daniel Cebra - Physics 295 Seminar

  5. Cosmic Gamma Ray Astronomy Ferenc, Bratton, Loftsdottir Daniel Cebra - Physics 295 Seminar

  6. 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. Daniel Cebra - Physics 295 Seminar

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

  8. 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. Daniel Cebra - Physics 295 Seminar

  9. Nuclear Matter Phase Diagram Big Bang GQP Temperature Heavy Ion Collision Hadronic Gas Neutron Stars Baryon Density Daniel Cebra - Physics 295 Seminar

  10. How to make a Quark-Gluon Plasma • Quantum Chromodynamics (QCD) predicts that heavy nuclei collided at ultra relatavistic energies will undergo a phase transition from ordinary hadronic matter to a quark-gluon plasma (QGP). Daniel Cebra - Physics 295 Seminar

  11. Daniel Cebra - Physics 295 Seminar

  12. History of the Rel. Heavy-ion Program • 76-92 Bevalac, Au @ 0.1 - 1.0 AGeV • 86-98 AGS, Au @ 2-10 AGeV • 86-00? SPS, Pb @ 40-160 AGeV • 91 RHIC approved • 00 Colliding beams at RHIC, 130Gev Daniel Cebra - Physics 295 Seminar

  13. Status of the AGS/SPS Results • AGS exps track the Hot Hadron gas region • Feb ‘00 - Press release on the observation of QGM at SPS Daniel Cebra - Physics 295 Seminar

  14. The Start of RHIC - Summer 00 Daniel Cebra - Physics 295 Seminar

  15. 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 Daniel Cebra - Physics 295 Seminar

  16. Daniel Cebra - Physics 295 Seminar

  17. The STAR Experiment - Plans Daniel Cebra - Physics 295 Seminar

  18. STAR - Under Construction Daniel Cebra - Physics 295 Seminar

  19. Daniel Cebra - Physics 295 Seminar

  20. The Detector Now... Daniel Cebra - Physics 295 Seminar

  21. Daniel Cebra - Physics 295 Seminar

  22. Daniel Cebra - Physics 295 Seminar

  23. The FIRST Event! Daniel Cebra - Physics 295 Seminar

  24. 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 Daniel Cebra - Physics 295 Seminar

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

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

  27. STAR Event -- Side View Daniel Cebra - Physics 295 Seminar

  28. STAR Calibration and Analysis • Spatial resolution 700 m • Tracking - better then 90% efficiency • dE/dx resolution = 8% • momentum resolution better than 1% p K p e Daniel Cebra - Physics 295 Seminar

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

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

  31. Daniel Cebra - Physics 295 Seminar

  32. Centrality: Participants vs. Spectators The collision geometry (i.e. the impact parameter) determines the number of nucleons that participate in the collision “Spectators” Only ZDCs measure Npart Zero-degreeCalorimeter “Participants” “Spectators” • Many things scale with Npart: • Transverse Energy • Particle Multiplicity • Particle Spectra Produced Particles Daniel Cebra - Physics 295 Seminar

  33. ZeroDegreeCalo 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 Daniel Cebra - Physics 295 Seminar

  34. ds/dN vs N Comparison to cascade models demonstrates to collective behavior of nuclear systems Used to determine centrality of collisions Daniel Cebra - Physics 295 Seminar

  35. Shapes of dNch/dh for different Npart %s Mean Npart 0-3 Data HIJING 354 15-20 216 35-40 102 dNch/dh dNch/dh Data HIJING (dNch/dh)/(½Npart) (dNch/dh)/(½Npart) h Daniel Cebra - Physics 295 Seminar h

  36. dN/dh Higher multiplicity than comparable p+p collisions indicates collective nature. Impressive agreement between the exps STAR PHENIX BRAHMS Daniel Cebra - Physics 295 Seminar

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

  38. Hydrodynamic Flow - Defined • Radial flow • Not seen in angular distributions • Use HBT, spectra (T = To + m<b2> • 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 Daniel Cebra - Physics 295 Seminar

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

  40. Hydrodynamic Flow - Results midrapidity : |h| < 1.0 V2 Hydrodynamic model Preliminary RQMD SPS AGS Centrality Daniel Cebra - Physics 295 Seminar

  41. Conclusions • Summer ‘00 Heavy-ion running was successful - physics results already. But the QGP question is not yet resolved. • RHIC should run heavy-ions for 6 months in ‘01 (also 1 month of proton running). • Detectors Continue to improve (5-10 years). • Future: eRHIC • Future: LHC Daniel Cebra - Physics 295 Seminar

  42. Compact Muon Solenoid Daniel Cebra - Physics 295 Seminar

  43. Advertisements... Daniel Cebra - Physics 295 Seminar

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

  45. Intramural Sports! • Basketball • Soccer • Softball • Other sports? Daniel Cebra - Physics 295 Seminar

More Related