Download - 111-July-2008ALICE EMCAL PPR Meeting Working Group 4 Summary/Plans Coordinators: J.L. Klay (Cal Poly) and M. Heinz (Yale) Contributing Members: Ken Read.

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


Simulations completed for CD-2

• 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


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


Conversion backgrounds

<10% convert before TRD/TOF R~428cm

Start of EMCAL:

(~20% reduction)

Track-matching cut eliminates these


Electron/Hadron Ratios

Need a minimum factor of 400 hadron rejection

*This plot should be redone


Track-Cluster matching

~90% track-cluster matching efficiency

Matched particles (mostly hadrons)

*Should be revisited

**Re-check efficiency in PYTHIA and HIJING

PYTHIA


Electron ID: p/E

What is the status of testbeam e/h?


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


B-Jet Rates

Expect several hundred 80 GeV B-jets per year

Should make annual statistics plot similar to electron rates


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))


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


Efficiencies

All sources

B-jets

Dalitz

ConversionsCharm

B-jets

B-jets B-jets

More stats needed, higher pT


W backgrounds

pT pT

EMCAL Acceptance EMCAL Acceptance

B-jet electrons W electrons

So far only a qualitative look

~10x higher stats


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


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)


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?


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


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

– Do we have grid-accessible space at pdsf/LLNL?

v4-11-Rev-02

v4-10-Rev-02

v4-10-Rev-02

v4-11-Rev-02

v4-12-Rev-02

v4-13-Rev-02