phenix heavy flavor measurements in the rhic ii era vince cianciolo rhic ii heavy flavor workshop...

PHENIX Heavy Flavor Measurements in the RHIC II Era

Vince CiancioloRHIC II Heavy Flavor Workshop

April 28, 2005

28/04/05 PHENIX RHIC II Heavy Flavor Measurements 2

Outline

• Why are we interested in heavy flavor?• PHENIX upgrades• RHIC II luminosity guidance• Into an era of precision heavy-flavor

measurements at RHIC…


Generic Advantages of Hard Probes

• Produced early– Sample medium

• Scale w/ Nbinary (in the absence of medium effects)– pp reactions calibrate

probes, allowing detection of medium effects, test pQCD

q: fast color triplet

g: fast color octet

Q: slow color triplet

QQbar: slow color singlet/octet

Virtual photon: colorless

Real photon: colorless

Unknown Medium

Inducedgluon radiation?

EnergyLoss?

Dissociation?

Controls


• Initial gluon density– Dominance of gluon fusion production mechanism

• Gluon spin structure function• Interaction of slow heavy quarks in the medium

– Less energy loss than light quarks?– Participation in flow?

• Test for additional thermal production• Onium production mechanism, suppression

pattern• Backgrounds for other interesting signals

– Drell-Yan, IM di-leptons

What would we like to know that heavy flavor measurements can tell us

about?


What can we measure?• Open heavy flavor (HF)

– y, pT dependence– Centrality dependence– Reaction plane dependence– Tagged HF jets– HF di-lepton correlations

• J/ – y, pT dependence– Centrality dependence– Reaction plane dependence– J/ - hadron correlations– Polarization ’, c and B contributions – Compare to ’,

• Everything should be studied vs. √s, collision species.


What have we measured (or collected data for)?

• Open heavy flavor (HF)– y, pT dependence e

– Centrality dependence e

– Reaction plane dependence e

– Tagged HF jets No– HF di-lepton correlations No

• J/ – y, pT dependence e

– Reaction plane dependence No– J/ - hadron correlations No– Polarization No ’, c and B contributions No – Compare to ’, No

• Everything should be studied vs. √s, collision species. e

e – Good start on exploratory measurementsc : 2.5 > pT (GeV/c) > 0.8

c+b : pT (GeV/c) < 4.5Species : dAu, pp, CuCu, AuAu

√s : 200 GeVStatistics : More is always better (allows reduction in statistical and systematic

errors)


Silicon Vertex Detector • Four barrel layers

– Two ALICE pixel bus layers– Two strip-pixel layers

• Four end-cap pixel layers• Displaced vertex (σ ~50 m)• Full azimuthal inner tracking

|η| < ~2.4– Improve acceptance for -jet

correlations, D K• Connect to tracks in central

and muon arms– Tag heavy flavor decays

• c,b e,• B J/

– Improve onium resolution– Eliminate decay hadrons– Reduce high-pT background


Nose Cone Calorimeter

• Replace central arm magnet nosecones (Cu) w/ tungsten-silicon calorimeters

• Coverage at forward/backward rapidity: 0.9 < |η| < 3.5 /0 separation for pT < 30

GeV/c – Jet identification

identification gives good acceptance for c J/ +


Muon Trigger Upgrade• Three layers of RPCs with 2D

(θ,φ) pad readout• Provides online momentum

measurement to improve Level-1 trigger rejection– Single-particle

• pT cut• W spin-measurements in pp

– Two-particle • Minv cut• onium measurements in AA

– Necessary to take complete advantage of luminosity upgrades

• Provides improved high-multiplicity background rejection


Disclaimer

• Be wary of Hypothetical Future Value predictions…

• As always, the Devil is in the details.

When rate estimates look too good to be true they probably are.


RHIC II Luminosity – CAD Guidance

x 35 increase for ppx 10 increase for CuCu

x 15 increase for dAux 15 increase for AuAu

http://rhicii-heavy.bnl.gov/doc/RHIC_II_Luminosity_Roser.xls


RHIC II Yields – ADF, MJL Guidance

• Assume CAD “Maximum Average” Luminosity Projection, 12 week runs, known PHENIX uptime (60%) to get Live Delivered Luminosity.

• Use measured values when possible to calculate pp σ’s, B.R.’s.• Assume nuclear scaling - (AB), w/=1 for , =0.92 for others.• Use stated RF efficiency, diamond size to get vertex cut efficiency.• Use measured PHENIX performance, assume PHENIX SiVTX, Nosecone

Calorimeter, Muon Trigger upgrades to get acceptances, efficiencies.


Yields

• Like to add in numbers for B->J/psi, single mu, single e, Drell Yan, D->Kpi, charm pairs, emuSignal/System pp (200 GeV) pp (500 GeV) CuCu AuAu dAu

J/ee 55,054 609,128 73,921 44,614 29,919

′(2S)ee 993 10,985 1,333 805 540

_c0J/ee 100 2,578 134 81 54

_c1J/ee 1,340 40,870 1,800 1,086 728

_c2J/ee 2,190 59,296 2,941 1,775 1,190

(0,1,2)ee 210 3,032 547 397 184

J/ 468,741 5,483,006 653,715 394,535 258,136

′(2S) 8,453 98,880 11,789 7,115 4,655

_c0J/ 3,822 99,824 5,330 3,217 2,105

_c1J/ 51,215 1,582,561 71,425 43,107 28,204

_c2J/ 83,702 2,296,069 116,732 70,451 46,095

(0,1,2) 528 7,723 1,429 1,035 469


Measuring Open Heavy Flavor in PHENIX

• Measurement of open heavy flavor in PHENIX is based on the semi-leptonic decay modes of B and D mesons.

• Other contributions to inclusive lepton spectra are determined and subtracted; remainder attributed to heavy flavor decays.

c c

0DK

0D

K-

+


Measuring Heavy Flavor (y=0) in PHENIX Cocktail Method

Inclusive electron spectrum in AuAu @ 200 GeV/c

• Many sources contribute to inclusive electron spectrum.

• Dominant contribution from 0’s (via Dalitz decay and conversion).

• These are very well measured by PHENIX in the same apparatus.

• S/B decreases w/ increasing pT.


Measuring Heavy Flavor (y=0) in PHENIX Converter Method

• At low-pT we directly measure dominant -conversion backgrounds by inserting an extra converter of known thickness.

• Dalitz contribution follows deterministically.• Statistics-limited at high-pT (rely on cocktail, OK since S/B

higher).

Non-

/ e

lect

ron r

ati

o

For pT > 0.8 GeV/c S/B > 0.4


Note: Bottom dominates for pT> 2.5 GeV/c

• Comparison with PYTHIA (tuned to available data)– pT < 1.5 GeV/c: reasonable

– pT > 1.5 GeV/c: spectra “harder” than PYTHIA

• hard fragmentation?• bottom enhancement?• higher order contributions?

pp Results

• Comparison with FONLL– Fixed Order Next-to-Leading Log

pQCD calculation (M. Cacciari, P. Nason, R. Vogt hep-ph/0502203)

– better description of spectral shape

– still room for further contributions• from jet fragmentation?

PHENIX data

consistent with STAR (PRL 94,

062301 (2005)) within errors!


Total Charm Yield Nbinary• Background-subtracted “heavy-

flavor” e± pT spectra vs. centrality w/ converter analysis

• Insufficient statistics at pT > 1.5 GeV/c to study modification of spectral shape

Total yield for pT > 0.8 GeV/c

• Total charm yield in AuAu agrees with binary scaled pp yield (as expected for point-like pQCD process)!

PHENIX: PRL 94, 082301 (2005)


Charm May Flow• PHENIX HF electron spectra @ 130 GeV/c are compatible w/

no interactions and also with hydrodynamics.• Measure flow, go to higher pT

Batsouli et al., Phys. Lett. B557, 26

S.S. Adler et al., nucl-ex/0502009

Theoretical predictions from Greco et al., Phys. Lett. B595, 202


Charm RAA(pT) 1

• Need to go to cocktail analysis to obtain sufficient statistics at high-pT.• Will lower systematics at low-pT by combining with converter method.

ppAA

AAAA dT

dNR

PHENIX Preliminary

RAA with yield above 2.5 GeV/c


Measuring Heavy Flavor at Forward Rapidity in the PHENIX Muon Arms

Z (cm)400 120

Final Decay

Muon flux

Total flux

I I hadron

Gap 0 1 2 3 4

II decay muon

log I

I (

part

icle

flux)

Reconstructed to gap4

I3I3inclusive

I3I3exclusive

Hadron punch-through

absorber

II prompt muon


Measuring Heavy Flavor at Forward Rapidity in the PHENIX Muon Arms

• Cocktail input not well-measured as in central-arm measurement.• Absorber thick, any error in strong interaction description amplified by ~e10.• Extract decay component from z-vertex slope of normalized muon yield.• Calculate punchthrough component with simplified absorption model:

• At low (high)-pT systematics dominated by decays (punchthroughs, competing c/b production)

Prompt muons

Punch-through hadrons

Decay muons

PHENIX PRELIMINARY


Expected D K statistical significance (S/√B) for different DCA cuts (pT > 2 GeV/c, 200M AuAu min. bias. events)

Synergistic Benefits of Detector/Luminosity Upgrades for Open Heavy Flavor Measurement

• Detector upgrades assist by determining decay vertex.– Allows direct measurement of

charm via D K– Reduces backgrounds at low-pT

– Allows statistical separation of c/b at high-pT

– Allows direct elimination of hadron decay muons.

• Luminosity upgrades extend pT reach and allow reduction of systematic errors.– Additional special runs (e.g., w/ different converter thicknesses and

locations, different field configurations, etc.)– Finer binning of DCA dependence for c/b separation.– Better determination of punchthrough absorption.


J/ in pp

In pp we’ve measured the close to pT = 0 and over much of the rapidity range.


J/ in dAu

Modest cold nuclear effects seen, but data are not sufficient to completely understand those effects.


Coalescence model (Thews et al)

y = 1.0

y = 4.0Stat. Model (Andronic et al.)

Absorption model (Grandchamp et al.)

Phys.Rev.C69, 014901,2004

J/ in AuAu

• Low-statistics measurement in central arm from Run-2. • Much larger data sets in central and muon arms from Run-4

are currently in production.


J/ in CuCu

• We’re just getting started, but we have nice mass peaks from near-line analysis of LVL2-filtered data.

central arm north muon arm


Synergistic Benefits of Detector/Luminosity Upgrades for

Onium Measurements• Statistics, statistics, statistics

– Higher pT coverage– More centrality bins– More systems, energies– Triggering improvements needed

for Level-1 di-muon triggering in ion collisions w/ RHIC II luminosity

– Polarization ′ and

• Background elimination– J/ background dominated by

hadron decays which can be largely eliminated w/ silicon detector.

• Resolution– Especially important for ′ and ’s

• Feeddown c J/ + (NC Calorimeter)– B J/ + X (Forward Silicon)

=1.0-1.5

Minv() – Minv()


Other HF Topics• cc e+e-

– Drell-Yan– IM di-leptons

• Gluon structure function• Charm-jet tomography

– Tag charm jet w/ electrons– Measure J/ near- and far-

side correlations

R. Rapp, nucl-th/0204003PHENIX PreliminaryNon-/h ΔΦ distributionsdAu, trigger-e in different pT bins

1 < pT(e) < 1.5

2 < pT(e) < 2.5

1.5 < pT(e) < 2

2.5 < pT(e) < 3


Conclusions• There’s a famous Indian fable about six blind men

who come to very different conclusions about the form of an elephant due to their limited examinations.

• With detector upgrades and RHIC II luminosities we can truly embark on precision heavy flavor measurements of sQGP (or whatever we choose to call the stuff we’ve made) and come to a better understanding of its full nature.

Wall?Fan?

Snake?

Spear?Rope?

Tree?

…Moral:

So oft in theologic wars, The disputants, I ween,

Rail on in utter ignorance Of what each other mean,

And prate about an Elephant Not one of them has seen!

John Godfrey Saxe (1816-1887)


• Backup slides


Silicon Vertex Detector – Details2D single-sided detectors for outer barrels

Modified BTeV chip for end cap readout

ALICE pixel bus for inner barrels

Vital stats


Silicon Vertex Detector - Coverage• Complete coverage of central arms• Nearly complete coverage of muon arms

– Two small regions w/ only two hit Si planes• Essentially 4 tracking for |η| < ~2.4


Nosecone Calorimeter – DetailsNot This Talk

e/m compartments Hadronic (leakage)

00// identifier identifier(strip-pixels)(strip-pixels)

downstream

Si Si padspads

tungstentungsten

upstream

Single layer of stripPixels


Muon Trigger Upgrade – Detailsscintillator HVRPC

Time resolution ~ 3.5 ns

Efficiency for cosmics

Raw signals

phenix heavy flavor measurements in the rhic ii era vince cianciolo rhic ii heavy flavor workshop...

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