Edouard Kistenev for the PHENIX Collaboration Calorimetry based upgrade to PHENIX at RHIC
Cold Nuclear Matter Effects on Open Heavy Flavor at RHIC J. Matthew Durham for the PHENIX...
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Transcript of Cold Nuclear Matter Effects on Open Heavy Flavor at RHIC J. Matthew Durham for the PHENIX...
Cold Nuclear Matter Effects on Open Heavy Flavor at RHIC
J. Matthew Durhamfor the PHENIX CollaborationStony Brook University
Matt Durham - WWND 2011 2
Open Heavy Flavor at RHIC
Phys. Rev. Lett. 98, 172301 (2007)
One of the most striking results from RHIC is the strong suppression and flow of heavy quarks in Au+Au collisions
d+Au
Au+Au
d+Au allows quantification of nuclear effects without complications of hot medium
Matt Durham - WWND 2011 3
Cold Nuclear Matter Effects
Phys. Rev. C 74, 024904 (2006)
Mass ordering of Cronin enhancement observed for π,K,p
Does this continue with D meson? B?
MD ~1.8 GeV
Closed heavy flavor is suppressed at mid-rapidity (details in Alex’s talk next)
Open heavy flavor in d+Au can shed light on these interesting phenomena
arXiv:1010.1246
Matt Durham - WWND 2011 4
Measurement Methodology
Direct Reconstruction:
Identify parent meson via
daughter products
Indirect Method:
Measure leptons from D/B decays
Straightforward triggering scheme
PHENIX is especially well suited for lepton measurements
Matt Durham - WWND 2011 52007-12-14
The PHENIX Experiment Electrons are tracked by
drift chamber and pad chamber
The Ring Imaging Cherenkov Counter is primary electron ID device
Electromagnetic calorimeters measure electron energy – allow E/p comparisons
BBC/ZDC provide MinBias trigger and centrality determination in HI collisions
e+e
Run-8 Configuration
Matt Durham - WWND 2011 6
Electron Sources Dalitz decays
Mostly Also from
Conversions in material Photons predominantly from
Kaon decays
Dielectron decays of vector mesons
Thermal/direct radiation Small but significant at high pt
Heavy Flavor Decays
ee 0
,,,
0
eeK 0
ee ,,
SIGNAL
BACKGROUND
Matt Durham - WWND 2011 7
Background Subtraction Methods Cocktail Method
PHENIX has measurements of most of the background electron sources.
A cocktail of these sources are subtracted from the inclusive electron sample to isolate the HF contribution.
Converter Method Extra material in the PHENIX
aperture intentionally increases background by a well defined amount.
Allows precise quantification of photonic background.
arXiv:1005.3674
Matt Durham - WWND 2011 8
Conversions Vast majority of conversion electrons come from photons
from , with kinematics very similar to Scale up Dalitz decay electrons by appropriate factor to
account for conversions (determined through simulation)
Cocktail Ingredients I Light mesons
Fit d+Au pion data with Hagedorn function Set other meson’s shape with mt-scaling Normalization set by particle ratios at high pt
2220mMpmp mesonttt
0 ee 0 0 ee 0
Matt Durham - WWND 2011 9
Cocktail Ingredients II Direct Photons
PHENIX p+p data, scaled up by Ncoll for each centrality
Ke3 decays Electrons from kaon decays away from the vertex are
mis-reconstructed at high pT.
Full simulation of PHENIX detector determines Ke3 contribution (only relevant at pT<1GeV/c)
A note on the J/ψ: We know J/ ψ is suppressed in d+Au We don’t yet have kinematic dependence of J/ ψ RdA
J/ ψ is significant at high pT, so knowledge of the exact behavior at pT>4GeV/c is necessary to correctly account for this contribution
As of now, J/ ψ is not subtracted
Matt Durham - WWND 2011 10
Total MB Cocktail
Matt Durham - WWND 2011 11
Converter Method
noninconv
nonoutconv
NNRN
NNN
)1(
For one day in Run-8, a brass sheet was wrapped around the beam pipe.
This increases photonic background by a well defined amount.
Precise measurements of converter material allow precise determination of Rγ via simulation
Matt Durham - WWND 2011 12
Cocktail and Converter Comparison
1
)1(
R
NNN
outconvinconv
Cocktail method gives a calculation of photonic background
Converter method gives us a measurement of photonic background
Difference is ~10% for all centralities.
Photonic cocktail components scaled to match converter data.
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Photonic Backgrounds
Excellent agreement between the two methods
Matt Durham - WWND 2011 14
Heavy Flavor Electron Spectra
Subtract cocktail from the inclusive electron sample to obtain the HF contribution
Black line is Ncoll scaled fit to p+p
With d+Au spectra, divide by scaled p+p reference to obtain RdA
ppT
eHFcoll
AudT
eHF
dAu
dpdNN
dpdN
R
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Peripheral RdA
Matt Durham - WWND 2011 16
Semi-Peripheral RdA
Matt Durham - WWND 2011 17
Semi-Central RdA
Matt Durham - WWND 2011 18
Central RdA
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Minimum Bias RdA
Matt Durham - WWND 2011 20
Peripheral RdA consistent with p+p
Enhancement in open HF yields at 1<pT<4 GeV/c for more central collisions
Suppression at the highest pT
Rcp allows examination of “turn-on” of these effects within d+Au (with much smaller systematics) Aud
T
eHF
coll
AudT
eHF
collcp
dpdN
N
dpdN
NR
8860
8860
200
200
1
1
A few comments on RdA
Matt Durham - WWND 2011 21
Rcp (40-60)/(60-88)
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Rcp (20-40)/(60-88)
Matt Durham - WWND 2011 23
Rcp (0-20)/(60-88)
Matt Durham - WWND 2011 24
Light Quarks Heavy Quarks
Phys. Rev. Lett. 101, 232301 (2008) arXiv:1005.1627
Phys. Rev. Lett. 98, 172302 (2007)
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At pT> 4 GeV/c:
AAAA RRe 0
dAdA RRe 0
At pT< 4 GeV/c:
AAAA RRe 0
Matt Durham - WWND 2011 26
Summary PHENIX now has a full suite of heavy flavor
measurements across a wide range of Ncoll and colliding systems.
The Run-8 d+Au data set shows: Enhancement of open HF at moderate pT Suppression at the highest pT
This new reference for A+A data suggests heavy quark energy loss in the medium is even greater than previously thought:
Is the apparent difference in energy loss for light and heavy quarks really just a CNM effect?
Matt Durham - WWND 2011 27
BACKUPS
Matt Durham - WWND 2011 28
A. Dion, QM09
Matt Durham - WWND 2011 29
Centrality Determination in d+Au
Matt Durham - WWND 2011 30
Matt Durham - WWND 2011 31
Heavy Flavor Electron Spectra
Matt Durham - WWND 2011 32
Heavy Flavor Electron Spectra
Matt Durham - WWND 2011 33
Heavy Flavor Electron Spectra
Matt Durham - WWND 2011 34
Heavy Flavor Electron Spectra