An experimental perspective on An experimental perspective on first jet measurements at LHC: first jet measurements at LHC: Lessons from RHIC Lessons from RHIC Dan Magestro, The Ohio State University ALICE-USA Collaboration Meeting October 15-16, 2005
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An experimental perspective on first jet measurements at LHC: Lessons from RHIC
An experimental perspective on first jet measurements at LHC: Lessons from RHIC. Dan Magestro, The Ohio State University. ALICE-USA Collaboration Meeting October 15-16, 2005. Jets in hadronic collisions. DM, Hard Probes 2004. High-energy hadronic collisions: collisions of constituent partons - PowerPoint PPT Presentation
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An experimental perspective on An experimental perspective on first jet measurements at LHC: first jet measurements at LHC: Lessons from RHICLessons from RHICDan Magestro, The Ohio State University
ALICE-USA Collaboration Meeting
October 15-16, 2005
ALICE-USA 10/2005 2 Dan Magestro, Ohio State University
Jets in hadronic collisionsJets in hadronic collisions
• High-energy hadronic collisions: collisions of constituent partonsHigh-energy hadronic collisions: collisions of constituent partons
• Each parton carries fraction (x) of hadron’s momentumEach parton carries fraction (x) of hadron’s momentum
• ““Hard-scattered” outgoing partons back-to-back in azimuth (Hard-scattered” outgoing partons back-to-back in azimuth (), ),
• not back-to-back in pseudorapidity (not back-to-back in pseudorapidity () due to different x) due to different x
p
p
Transverse planeSide view of collision
DM, Hard Probes 2004
ALICE-USA 10/2005 3 Dan Magestro, Ohio State University
Jets as probes of nuclear collisions - 1Jets as probes of nuclear collisions - 1
1.1. Partons in vacuum fragment characteristically Partons in vacuum fragment characteristically →→ calibratedcalibrated probe probe
Can it be calibrated at LHC? Can it be calibrated at LHC?
part
on gq,
Particle Data Group, PLB 592 (2004)
= pT(hadron) / pT(parton)
ALICE-USA 10/2005 4 Dan Magestro, Ohio State University
1 fm/c 5 fm/c 10 fm/c 50 fm/chadronization
initial state
pre-equilibrium
QGP andhydrodynamic expansion
hadronic phase
Jets as probes of nuclear collisions - 2Jets as probes of nuclear collisions - 2
, K, p
spec
tra
Mom
entu
m-s
pace
anis
otro
py
Partic
le ra
tios
Reson
ance
pro
ducti
on
HBT inte
rfero
met
ry
Nuclea
r coa
lesce
nce
Strang
e ba
ryon
spec
tra
QCD har
d sc
atte
ring,
jets
Heavy
par
ticles
(cha
rm)
Nuclea
r mod
ificat
ion
Direct
phot
ons,
lepto
ps
QCD har
d sc
atte
ring,
jets
2.2. Hard parton scatterings early in collision Hard parton scatterings early in collision directdirect probe probe
• ALICE is the only LHC detector that will measure all HI observablesALICE is the only LHC detector that will measure all HI observables
ALICE-USA 10/2005 5 Dan Magestro, Ohio State University
• Multiple jets + background reduces Multiple jets + background reduces purity at “intermediate” Epurity at “intermediate” ETT
• Trigger capabilities NEEDED to Trigger capabilities NEEDED to access high Eaccess high ETT
Taken from B. Wyslouch, Hard Probe 2004
ALICE-USA 10/2005 16 Dan Magestro, Ohio State University
LHC operations planLHC operations plan
• Main objectives:Main objectives:
• Terminate installation in Febr. 2007Terminate installation in Febr. 2007
• First pp collisions in summer 2007, First pp collisions in summer 2007, √s = 14 TeV√s = 14 TeV
• First long heavy ion (Pb+Pb) run end of 2008, First long heavy ion (Pb+Pb) run end of 2008, √s = 5.5 TeV√s = 5.5 TeV
• Higher jet rates: first jet-quenching questions can be answered Higher jet rates: first jet-quenching questions can be answered with ~10with ~1044-10-1055 events, e.g. prediction for events, e.g. prediction for strong pstrong pTT dependence of dependence of
energy lossenergy loss
• Parallel efforts statistical & reconstructed jets needed to explore Parallel efforts statistical & reconstructed jets needed to explore full pfull pTT range range
ALICE-USA 10/2005 17 Dan Magestro, Ohio State University
An opportunity for early Pb beam? An opportunity for early Pb beam?
• Pb ions may be available at very early stage of LHC operationPb ions may be available at very early stage of LHC operation
• Jowett (CERN): Likely short Pb “Pilot Run” end of p+p Pilot Run in Jowett (CERN): Likely short Pb “Pilot Run” end of p+p Pilot Run in late 2007late 2007
• Depends on ability to commission ion cycle in SPS in 2006Depends on ability to commission ion cycle in SPS in 2006
• Luminosity = (few) x 10Luminosity = (few) x 102424 cm cm-2-2ss-1-1 ~10~1055 events in < 1 day events in < 1 day
This could be a great opportunity to answer first (zeroth) energy loss