daniel cebra - physics 295 11-feb-04 experimental nuclear physics at uc davis ps… check out our...
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Daniel Cebra - Physics 29511-Feb-0411-Feb-04
Experimental Experimental Nuclear Physics at Nuclear Physics at
UC DavisUC Davis
PS… Check out our web page at http://nuclear.ucdavis.edu
• FACULTY:• Jim Draper (emeritus)• Paul Brady (emeritus)• Daniel Cebra• Ramona Vogt
• STAFF:• Juan Romero• Tom Gutierrez
• GRAD STUDENTS:• Roppon Picha (2005)• Brooke Haag (2006)
• UNDERGRADS:• David Cherney• Stephen Baumgarten• Matt Searle• Orpheus Mall
Come visit us on the fifth floor - WEST end
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
Recent GraduatesRecent 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
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
BasicsBasics
Hadrons =Made of quarks
Baryon = 3 qmeson = q q
p = uudn = udd+ = udK+ = us
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
1) Goal: Use relativistic collisions of nuclear to create hot dense matter which reproduces the earliest stages of the universe
Relativistic Heavy Ion Physics:Relativistic Heavy Ion Physics:Creating Mini-`Big Bangs’ in the LaboratoryCreating Mini-`Big Bangs’ in the Laboratory
PS… Check out our web page at http://nuclear.ucdavis.edu
2)2) Now, Now, how do how do we do we do this?this?
(In Theory)(In Theory)
Daniel Cebra - Physics 295 111-Feb-0411-Feb-04
Brief History of the RHIC ProjectBrief 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 200 GeV collisions
• 2003 d+Au collisions
STAR
PHOBOSBRAHMS
PHENIX
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
3) How do we really do this?3) How do we really do this?
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
Data setsData sets Au+Au
s=130 GeV NEvent=0.7 M
Au+Au s=200 GeV NEvent= 3.2 M
Au+Au s=19.6
GeV NEvent=~20k
d+Au s=200 GeV NEvent=35 M
jet
pp• un-polarized• vertical pol. 391/nb• longitudinal pol. 373/nb (spin flip snake) Level-3 trigger, rare probesEMC jet trigger
Particle Identification: dE/dx
resolution ~8%
cold partonic/nuclear matter
hot partonic/nuclear matter
?
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
• 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
The Relevant Questions
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
Local Thermal Equilibrium?Local Thermal Equilibrium?
T
thermalsource
explosivesource
T,
pT
light
heavy
pT
light
heavy
T
mA
dm
dN
mT
TT
exp1
Fits assuming a hubble-like expansion yields temperatures of 90 MeV and average radial expansion velocities of 0.6c
~½m<v>2
Conclusion: The Final freeze-out state has reached a local thermal equilibrium.
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
The The HottestHottest matter in the Universe matter in the UniverseScientists 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
•Magnetic Cooling 90 K
•Ion Trapping 10 nK (1999)
•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
Relativistic Heavy Ion ColliderBrookhaven National Laboratory
Upton, New York
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
Is it the Right Temperature ?Is it the Right Temperature ?
Phase boundary lattice QCD:Allton et al.hep-lat/0204010
Tc=1603.5 MeVb=72535 MeV=0.3-1.3 GeV/fm3
At RHIC, we see evidence that the quarks freeze-out at the expected QPG transition temperature
hep-lat/0106002
Statistical fit Result: T=176 MeV B=41 MeV (130 GeV),
T=177 MeV B=29 MeV (200 GeV)
T=2.1·1012 K
Sun 15.6·106 K
Supernova~109 KPlasma fusion
55·106 KLaser fusion4·106 K
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
Bulk Properties 1: Directed Flow or V1 Bulk Properties 1: Directed Flow or V1 X
Z b
XZ – the reaction plane
Picture: © UrQMD
rapidity
<px> or v1
Developed early - pre - equilibrium !Sensitive to the EOSAs important as radial flowWell studied at lower energiesHard to be measured at RHIC because it is small
STAR Data
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
Bulk Properties 2: Elliptic Flow or V2Bulk Properties 2: Elliptic Flow or V2
Significant v2 up to ~7 GeV/c in pt, the region where hard scattering begins to dominate.
Expected Hydrodynamical Behavior
Hard Scattering dominated region, but still showing some V2
Profile of Source
v
dddP d
dddP d
T
T
2
2
2
2
2
2
2
cos( )
cos
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
Jets at RHICJets at RHIC
p+p jet+jet (STAR@RHIC)
Au+Au ??? (STAR@RHIC)
nucleon nucleonparton
jet
Find this……….in this
pQCD estimateET>1 GeVNJet~500
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
Strong suppression of back-to-back correlations in central Au+Au
Azimuthal distributions in Au+AuAzimuthal distributions in Au+AuAu+Au peripheral Au+Au central
Near-side: peripheral and central Au+Au similar to p+p
pedestal and flow subtracted
Phys Rev Lett 90, 082302
?
Daniel Cebra - Physics 29511-Feb-0411-Feb-04
Have we found the Quark Gluon Have we found the Quark Gluon
Plasma at RHIC?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
We have yet to do:
• Study the properties of the QGP matter
• Relate these properties to the nature of the Universe (Big Bang)
This represents significant progress in our understanding of strongly interacting matter