1. “It is better to begin in the evening than not at all”
Present and future measurements on hadronization in strongly interacting partonic matter at RHIC and RHIC-II.
“It is better to begin in the evening than not at all”
Old English Proverb

2. Particle production in RHI collision
SPS, RHIC-I
LHC, RHIC-II
Hydro
pQCD
Parton recombination and coalescence
Medium modified fragmentation (jet quenching)
Fragmentation
Soft
~ 2 GeV/c
~ 6 GeV/c
~ 30 GeV/c ? pT

3. Reaching the fragmentation regime
QM’05
Same RCP for pT>~5 GeV
RAA flat for pT > 5 GeV
Dominance of fragmentation pT > 5 GeV/c - medium modified

4. Calculated fragmentation functions
C. Bourrely and J. Soffer, PRD 68 (2003) z
Parton fragmentation functions to p and  vary as function of z
If energy loss in medium different for light and heavy quarks will see differences in p-p and A-A
Au-Au not enough - Need measurements in p-p

5. First “direct” look at medium modification
QM’ 05
pT(assoc) > 2 GeV/c
1/Ntrig dN/d(Df)
Au+Au, 0-5%
STAR Preliminary
8 < pT(trig) < 15 GeV/c
Emergence of the away side peak with increased trigger pT
Away-side D(zT) suppressed,
shape unchanged
No striking flavor dependence of modification - need PID

6. PID jet correlations Need more stats and measure of z
Au+Au 0-5% 1.0<pTAssociated<2.0
50% p/pbar Λ
Λbar
95% п
K0s
Near Side
Nch/NTrigger
pTTrigger
Near side – more likely to findp
Away side – find p orp
Meson/baryon difference?
Need more stats and measure of z

7. Large acceptance in h and f essential
Can we do that?
Large acceptance in h and f essential
pq,g > 10 GeV/c
all h
106 particles in AA
Need triggering
g tagged jets
Multiply pp events by factor of ~ 8 x 1015 for
AuAu events in 30 nb-1 RHIC year
RHIC-II luminosities essential

8. Comprehensive new detector at RHIC (R2D)
HCal and m-detectors
Superconducting coil (B = 1.3T)
Vertex tracking
RICH
Aerogel
EM Calorimeter
ToF
Tracking:
Si, mini-TPC(?),
m-pad chambers
PID:
Forward tracking:
2-stage Si disks
Forward magnet
(B = 1.5T)
Forward spectrometer:
(h = )
EMCal (CLEO)
HCal (HERA)
m-absorber
|h|  1.2
h = 1.2 – 3.5
Central detector (|h|  3.4)
SLD magnet 6m

9. Detector coverage PID (p, K, p) Hadronic and EM Calorimetry:
η = +/- 3.4
Tracking: η = (-3.5 – +4.5)
PID:  = +/- 1.2 (2.8)
RICH : C5F12 - n =
p (GeV/c)
A1+ToF
A1+A2+RICH
RICH
dE/dx, ToF
PID (p, K, p)

10. Summary The New Comprehensive Detector designed for the
new era of UNIQUE physics at RHIC-II :
High rates
Large acceptance
High pT tracking
PID out to high pT
Good momentum resolution
Understand medium produced via jets/leading particle
New (as yet) undetermined physics
Large program of measurements for RHIC-II era

11. Requirements for an Ideal Detector
High rate detectors, DAQ
Required for high luminosity A+A, p+A and p+p collisions at RHIC II
Uniform high magnetic field over “large volume”
Good quality tracking/momentum measurements
Precision Vertex tracking
4 EM and Hadronic Calorimeters
Missing energy measurements and  identification
e/h discrimination
At low pT as well as at high pT
/K/p identification
Momentum up to ~ 25 GeV/c
Forward capabilities
High-rapidity measurement/identification possibility

12. Geometrical Dependence of RAA
RAA scales smoothly
See poster, van Leeuwen (91)

13. Can’t rely too heavily on NLO calculations
p+p->p0 + X
Work for light mesons
don’t work for heavy baryons