11-July-2008 ALICE EMCAL PPR Meeting 1 Working Group 4 Summary/Plans Coordinators: J.L. Klay (Cal Poly) and M. Heinz (Yale) Contributing Members: Ken Read (Tennessee) Josh Hamblen (Tennessee) Irakli Martashvili (Tennessee) Ben Rizzo (Creighton) Postdoc (Creighton) Sebastien Gadrat (Grenoble) Brandon Boswell (Cal Poly) Christopher Brown (Cal Poly) (Mostly) Summer “Not available” after 01-Oct- 2008 August-November Coordination only after 01- Oct-2008 after 15-August
• Electron, W and B-jet rates (PYTHIA only)• Electron and Hadron Background rates (PYTHIA only)
– Including photon conversions (full detector included, no reco)
• Electron track-matching and PID (Full simulation + Full reconstruction)– Efficiency and e/h discrimination
• Preliminary DVM technique for semi-leptonic decays– Background rejection
• Preliminary W-jet rejection
Reasonably final:
Good start, but need more effort:
Note: Noise, other sim parameters have changed since CD-2 simulations. We may want to re-do everything with latest version of AliRoot, newer cuts, etc
11-July-2008 ALICE EMCAL PPR Meeting 3
Electron rates
L=0.5mb-1, 1yr =106 s, Pb-Pb scaling
~5000 B-electrons
*This plot should be redone
Need to double-check that these rates agree with
MNR NLO
11-July-2008 ALICE EMCAL PPR Meeting 4
Conversion backgrounds
<10% convert before TRD/TOF R~428cm
Start of EMCAL:
(~20% reduction)
Track-matching cut eliminates these
11-July-2008 ALICE EMCAL PPR Meeting 5
Electron/Hadron Ratios
Need a minimum factor of 400 hadron rejection
*This plot should be redone
11-July-2008 ALICE EMCAL PPR Meeting 6
Track-Cluster matching
~90% track-cluster matching efficiency
Matched particles (mostly hadrons)
*Should be revisited
**Re-check efficiency in PYTHIA and HIJING
PYTHIA
11-July-2008 ALICE EMCAL PPR Meeting 7
Electron ID: p/E
What is the status of testbeam e/h?
11-July-2008 ALICE EMCAL PPR Meeting 8
Electron ID: summary
For pT>10 GeV/c, pion rejection is well above the factor 400 needed
High efficiency
*Add a few more efficiency curves?
*Should be re-done
11-July-2008 ALICE EMCAL PPR Meeting 9
B-Jet Rates
Expect several hundred 80 GeV B-jets per year
Should make annual statistics plot similar to electron rates
11-July-2008 ALICE EMCAL PPR Meeting 10
Displaced Vertex Method
• The method pursued here has previously been used by CDF to identify secondary vertices from semi-leptonic decays.
• Breakdown of method:– Find a high-pt electron trigger
particle in EMCAL– Pair with all charged hadrons within
a cone of radius dR.– Reconstruct “approximate” (average
between B-D decay) secondary vertex and apply more cuts to reduce backgrounds from other leptonic decays.
– Plot Lxy distribution and obtain B-contribution from positive/negative imbalance
D0
B-
e-
K/e
Pe+K
r
PrimVtx
SecVtx
Lxy= r .pe+k / |pe+k|
Lxy
CDF Phys.Rev.D66 (2002))
11-July-2008 ALICE EMCAL PPR Meeting 11
Signal vs. Backgrounds
• Electron pT-cut > 10 GeV/c• Min. 6 ITS-hits on both electron/hadron track• Inv mass of (elec-kaon) mass > 1.7 GeV• Pair DCA < 200 m• B-Tag = |Lxy| > 600 m
Bottom Signal
Backgrounds
Cuts used for analysis
11-July-2008 ALICE EMCAL PPR Meeting 12
Efficiencies
All sources
B-jets
Dalitz
ConversionsCharm
B-jets
B-jets B-jets
More stats needed, higher pT
11-July-2008 ALICE EMCAL PPR Meeting 13
W backgrounds
pT pT
EMCAL Acceptance EMCAL Acceptance
B-jet electrons W electrons
So far only a qualitative look
~10x higher stats
11-July-2008 ALICE EMCAL PPR Meeting 14
DVM Comparison: B-jet vs WB-jets W
Standard cuts
Standard cuts +Minv> 1.7 GeV(charm rejection)
Standard cuts +Minv> 1.7 GeV + Max ITS-hits
Blue = right - leftMore
statistics needed
11-July-2008 ALICE EMCAL PPR Meeting 15
DVM results
After applying DVM cuts the signal efficiency is ~30-40%, whereas the backgrounds are factor ~100 suppressed.
Electrons from all sources (before DVM method)
Electrons from all sources (after DVM method)
11-July-2008 ALICE EMCAL PPR Meeting 16
What’s needed for PPR• Revisit rate calculations with higher statistics• Re-check e-ID with newer AliRoot• Electron and Electron-Jet Trigger
– Rates and backgrounds?
• Electron Spectra/RAA studies– Investigate electron heavy meson (Charm/Bottom) correspondence in AA– Compare to TPC alone and TPC+TRD vs. with EMCAL
• D/B Spectra/RAA studies– DVM method for B-mesons through e+D– Displaced vertex reconstruction of B through J/psi+K– Compare to electron RAA
• B-jet studies – DVM B-jet selection
• Effect of mis-identified electron/hadrons?
– W rejection – Study of alternative tagging methods/algorithms– Combine DVM method and electron ID with JETAN
• Cone and FastJet objects• FF performance for B-jets• Effect of mis-identified B-jets on FF
Effect of mis-identified electron/hadrons?
11-July-2008 ALICE EMCAL PPR Meeting 17
Preliminary work matrixTask Tools Manpower Statistics
Revisit rates
(higher stats)
PYTHIA + Material ---kinematics info
0.5 person 100k x 15 jet pT bins
Re-check e-ID (track-matching, p/E)
PYTHIA/HIJING + Full simulation
0.5 person Single e, 0 10k x ~10 pT ranges
100k x 15 jet pT bins + 10k HIJING bkg
Electron and E-Jet trigger
(rates/bkg)
PYTHIA/HIJING + AliEMCALTrigger, HLT
Trigger Group?
100k x 15 jet pT bins + 10k HIJING bkg
Electron spectra/RAA
(eB/D corresp., compare to TPC and TPC+TRD)
PYTHIA + Full simulation
1 person 100k x 15 jet pT bins
100k x ~5 pThard bins each of MSEL4 and MSEL5
D/B Spectra/RAA
(e+D, J/Psi+K, mis-ID)PYTHIA + Full simulation
1-2 people 100k x 15 jet pT bins
100k x ~5 pThard bins each of MSEL4 and MSEL5
B-jets (DVM,W,JETAN reco, FF, other tag methods)
PYTHIA/HIJING + Full simulation
2-3 people 100k x ~5 pThard bins each of MSEL4 and MSEL5
50-100k W-boson decays
10k HIJING bkg
11-July-2008 ALICE EMCAL PPR Meeting 18
ALICE Grid resources available• PDC08 simulations used a few different AliRoot versions
– http://pcalimonitor.cern.ch/job_details.jsp
– EMCAL was in for all of these runs
– At Offline week we were encouraged to submit requests• CPU is not a problem• Storage for our files is the major issue
