Transcript Physics295-winter04

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=1603.5 MeV
mb=72535 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