single particle probes of d+au collisions in phenix

Zvi CitronZvi Citron

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Single Particle Probes of d+Au Collisions in PHENIX

Zvi Citron for PHENIX


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Outline

•Motivation

•Improvements in the 2008 RHIC Run data set

•Using the Forward and Backward Rapidity Detectors in PHENIX

•Analysis of the Modification of Mid-Rapidity Yields Conditioned on Forward Rapidity Triggers

•Results in d+Au

•Conclusions and Future Prospects

•Motivation

•Improvements in the 2008 RHIC Run data set

•Using the Forward and Backward Rapidity Detectors in PHENIX

•Analysis of the Modification of Mid-Rapidity Yields Conditioned on Forward Rapidity Triggers

•Results in d+Au

•Conclusions and Future Prospects


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Motivation•The d+Au collision system allows investigation of cold nuclear matter effects, and insights into initial state conditions.

•2008 RHIC Run (Run 8) has a factor of ~30 increase in statistics over 2003 RHIC Run (Run 3).

•Forward and backward rapidity detectors provide access to different x regions within the Au nucleus and thereby probe the nuclear structure function.

•By using the forward rapidity calorimeters in PHENIX (MPCs) to trigger on an event, we can investigate the modification of the mid-rapidity spectra under these trigger conditions to learn about the initial state conditions.

•The d+Au collision system allows investigation of cold nuclear matter effects, and insights into initial state conditions.

•2008 RHIC Run (Run 8) has a factor of ~30 increase in statistics over 2003 RHIC Run (Run 3).

•Forward and backward rapidity detectors provide access to different x regions within the Au nucleus and thereby probe the nuclear structure function.

•By using the forward rapidity calorimeters in PHENIX (MPCs) to trigger on an event, we can investigate the modification of the mid-rapidity spectra under these trigger conditions to learn about the initial state conditions.


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Quality of the Run 8 d+Au Dataset

•Factor of ~30 increase in statistics will allow for greatly improved study of 0, , and thus also direct at mid-rapidity.

•These studies are underway and will shed more light on cold nuclear matter effects.

•Factor of ~30 increase in statistics will allow for greatly improved study of 0, , and thus also direct at mid-rapidity.

•These studies are underway and will shed more light on cold nuclear matter effects.

Mid rapidity mass spectra show ability to measure both 0 and at high pT.

Mid rapidity mass spectra show ability to measure both 0 and at high pT.


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Expanded Reach in pT

•pT reach extended by ~5 GeV/c with respect to published data (Phys. Rev. Lett. 98, 172302 (2007)) •Much improved statistical precision.

•pT reach extended by ~5 GeV/c with respect to published data (Phys. Rev. Lett. 98, 172302 (2007)) •Much improved statistical precision.

See Ondrej Chvala’s poster #210!See Ondrej Chvala’s poster #210!

Mid-rapidity raw 0 spectraMid-rapidity raw 0 spectra


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Charged Hadrons at Mid-Rapidity

•Run 8 allows better precision in the measurement of the mid-rapidity charged hadron nuclear modification factor. •Black bands represent scale uncertainty

•Run 8 allows better precision in the measurement of the mid-rapidity charged hadron nuclear modification factor. •Black bands represent scale uncertainty


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Forward Rapidity Detectors Allow Access to Different x Regions

€

x1=PTseY3+eY4( )

x2=PTse−Y3+e−Y4( )

x1 x2x1 x2

Y3, pT

Y4, pT

Low x at a large rapidity gap.

Note: these formulae do NOT take into account the fragmentation function or kT smearing.

Note: these formulae do NOT take into account the fragmentation function or kT smearing.


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dAu

NORTH MPC3.1<<3.7

NORTH MPC3.1<<3.7

SOUTH MPC-3.1>>-3.7

SOUTH MPC-3.1>>-3.7

•Trigger on forward (or backward) identified 0 or unidentified calorimeter cluster. •Detector acceptances are symmetrized.

•Trigger on forward (or backward) identified 0 or unidentified calorimeter cluster. •Detector acceptances are symmetrized.

0/Inclusive Cluster0/Inclusive Cluster

h±h±h±h±0/Inclusive Cluster0/Inclusive Cluster

In the PHENIX Detector

Central Arm ||<0.35Central Arm ||<0.35


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Analysis Procedure

•Look at events in which a high energy pi0 or inclusive cluster trigger is found in one of the MPCs (3.1<||<3.7)

• Inclusive calorimeter clusters for higher energies.

•Measure the inclusive central arm per trigger yield of charged hadrons in the sub-samples (||<0.35)

•Compare North and South in symmetric p+p system to confirm integrity of the procedure

•Compare d going side to Au going side to look for saturation, shadowing

•Look at events in which a high energy pi0 or inclusive cluster trigger is found in one of the MPCs (3.1<||<3.7)

• Inclusive calorimeter clusters for higher energies.

•Measure the inclusive central arm per trigger yield of charged hadrons in the sub-samples (||<0.35)

•Compare North and South in symmetric p+p system to confirm integrity of the procedure

•Compare d going side to Au going side to look for saturation, shadowing

At E>~17 GeV can no longer distinguish 0 from At E>~17 GeV can no longer distinguish 0 from

reconstruct 0reconstruct 0


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p+p :Symmetric Results in a Symmetric System

In a symmetric system there is good agreement in the two.In a symmetric system there is good agreement in the two.

Raw

Cou

nts

Raw

Cou

nts

Raw energy spectra of the North and South MPCs in p+p collisionsRaw energy spectra of the North and South MPCs in p+p collisions


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p+p :Symmetric Results in a Symmetric System

p

0/Inclusive Cluster in MPC N


h±h±h±h±

0/Inclusive Cluster in MPC S


p

N triggered mid-rapidity h±

S triggered mid-rapidity h±S triggered mid-rapidity h±

In symmetric system forward trigger = backward triggerIn symmetric system forward trigger = backward trigger


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Ratio of d Going Side to Au Going Side Triggered Yields

d Au



h±h±h±h±



h±/ h±h±/ h±

•Most central bin, <Ncoll> =15.4

0 Trigger in MPC with 9.1<E<12.7 GeV

•Most central bin, <Ncoll> =15.4

0 Trigger in MPC with 9.1<E<12.7 GeV

(d g

oing

sid

e tr

igge

r)/(

Au

goin

g si

de t

rigge

r)(d

goi

ng s

ide

trig

ger)

/(A

u go

ing

side

trig

ger)

<Ncoll> =15.4<Ncoll> =15.4

Shadowing, saturation, or other effects may lead to non unity ratio in mid-rapidity trigger associated spectra.

Shadowing, saturation, or other effects may lead to non unity ratio in mid-rapidity trigger associated spectra.


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Centrality Dependence of the Ratio

pT [GeV/c], ||<0.35pT [GeV/c], ||<0.35

The ratio of d going side to Au going side 0 triggered inclusive mid-rapidity spectra. The ratio of d going side to Au going side 0 triggered inclusive mid-rapidity spectra.

5.5 < E trigger < 9.15.5 < E trigger < 9.1 9.1< E trigger < 12.79.1< E trigger < 12.7 12.7 < E trigger < 16.4 [GeV]12.7 < E trigger < 16.4 [GeV]Most CentralMost CentralSemi-CentralSemi-CentralSemi-PeripheralSemi-PeripheralMost PeripheralMost Peripheral

(d g

oing

sid

e tr

igge

r)/(

Au

goin

g si

de t

rigge

r)(d

goi

ng s

ide

trig

ger)

/(A

u go

ing

side

trig

ger)


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(d side triggered)/(Au side triggered) Ratio Trends

The suppression of the d going side triggered yield relative to the Au going side triggered yield as a function of the trigger energy. (Bands indicate systematic uncertainties from the centrality bias associated with the trigger requirement and possible asymmetries stemming from the higher multiplicity in the Au going side MPC.)

The suppression of the d going side triggered yield relative to the Au going side triggered yield as a function of the trigger energy. (Bands indicate systematic uncertainties from the centrality bias associated with the trigger requirement and possible asymmetries stemming from the higher multiplicity in the Au going side MPC.)

Inclusive Cluster TriggerInclusive Cluster Trigger0 Trigger0 Trigger

,3.1<||<3.7,3.1<||<3.7


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Conclusions and Future Prospects•The 2008 RHIC d+Au run is a fruitful source of information on cold nuclear matter effects.•Further analysis will increase our understanding of d+Au collisions and their implications for initial state effects. “Controlling our control”.•The forward (d going) side triggered mid-rapidity inclusive charged hadron spectra is suppressed compared to the backward (Au going) side triggered sample.•We are thinking about how to understand these results in terms of shadowing/anti-shadowing, saturation.

•Future analysis underway to measure IdAu with forward/backward and trigger/associated•See also Jiangyong Jia’s posters (217 & 218) for other interesting d+Au results.

•The 2008 RHIC d+Au run is a fruitful source of information on cold nuclear matter effects.•Further analysis will increase our understanding of d+Au collisions and their implications for initial state effects. “Controlling our control”.•The forward (d going) side triggered mid-rapidity inclusive charged hadron spectra is suppressed compared to the backward (Au going) side triggered sample.•We are thinking about how to understand these results in terms of shadowing/anti-shadowing, saturation.

•Future analysis underway to measure IdAu with forward/backward and trigger/associated•See also Jiangyong Jia’s posters (217 & 218) for other interesting d+Au results.


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Backups


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0 in MPC South


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0 in MPC North

single particle probes of d+au collisions in phenix

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