STAR Run-8 Achievement & Summary

STAR Run-8 Achievement & Summary

Akio Ogawa

for the Collaboration

RHIC-AGS Users Meeting29 May 2008

At BNL

STARSTAR

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STARSTAR STAR Run8 Goals

Main Physics Goals• Gluon saturation in relativistic heavy nuclei• Transverse single spin asymmetries of forward 0

• (Transverse single spin asymmetries of gamma-jet) • (x-dependence of gluon polarization)• Non-photonic electron, Upsilon and D-mesons• Low energy AuAu test run

Detector Upgrades:• Commissioning of pp2pp• Commissioning of Forward Meson Spectrometer (FMS)• Commissioning of DAQ1000• Commissioning of TOF

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STARSTAR STAR Run8 (Modified) Goals




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STARSTAR 1st part

Main Physics Goals• Gluon saturation in relativistic heavy nuclei• Transverse single spin asymmetries of forward

0


Detector Upgrades:• Commissioning of pp2pp• Commissioning of Forward Meson Spectrometer

(FMS)• Commissioning of DAQ1000• Commissioning of TOF

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STARSTAR 2nd part




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STARSTAR STAR Setup 2008

Charged Particle Tracking:•Main TPC 1/24 with DAQ1000•Forward TPC (FTPC)

Particle ID:•MRPC ToF (parts)Calorimetry:•Photon Multiplicity Detector (PMD)•Barrel EMC•Endcap EMC•Forward Meson Spectrometer

Event Characterization & Trigger:•Beam-Beam Counter (BBC)•Zero Degree Calorimeter (ZDC)•Forward Pion Detectors (FPD)

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STARSTAR Why is forward rapidity interesting?

Forward scattering probes asymmetric partonic collisions Mostly scattering of

high-x valence quarks (with known & large polarization)0.25 < xq < 0.7

on low-x gluons

0.001 < xg < 0.1

NN

q

gPN

xqpNxgpN

PN

With heavy nucleus target, gluon density would be even bigger

xg ~ few 10-4

=Au

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STARSTAR p+p and d+Au 0+0+X correlations with forward 0

Conventional shadowing will change yield, but not angular correlationCoherent effects such as CGC evolution will change the angular correlationSensitive to xg ~ 10-3 in pQCD scenario; few x 10-4 in CGC scenario.

pp

dAudAuR

197*2

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BRAHMS

STAR

PRL 97, 152302

Back-to-back correlation

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STARSTAR

FMS Integrated Luminosity Goal = 30 nb-1

0.00

10.00

20.00

30.00

40.00

50.00

60.00

1/3/2008

1/8/2008

1/13/2008

1/18/2008

1/23/2008

1/28/2008

Run8 integrated luminosity at STAR

Triangles are with final or near-final PMT gains

Original goal

Reduced goal

Diamonds show data taken with a broad range of HV settings

Also have ~660M FMS+fast-detector minbias events

Final total: 49 nb-1

dAu Slow Luminosity (nb-1)

dAu

87% of goal

CGC reference data

Sampled 7.8 pb-1

Integrated Luminosity (nb-1)Goal 9 pb-1

pp

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STARSTARForward single-spin asymmetries in STAR

Large transverse single-spin asymmetries at large xF

xF dependence matches Sivers effect expectations qualitatively (but not quantitatively)

pT dependence at fixed xF not consistent with 1/pT expectation of pQCD-based calculations

arXiv:hep-ex/0801.2990

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STARSTARForward single-spin asymmetries

Acceptance of FMS and projected RHIC performance will enable…

• Further reach for inclusive and heavy mesons

• Spin-dependent near-side correlations () separation of Sivers and Collins effects

• Spin-dependent away-side correlations (-jet) isolation of Sivers effect

• Embark on spin-dependent inclusive and +jet

Projections for 9 pb-1 P=70%

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STARSTAR

Collins mechanism: Transversity (quark polarization) * asymmetry in the jet fragmentation

Sivers mechanism: Correlation between nucleon spin and parton kT

AN and Sivers and Collins effect

Phys Rev D41 (1990) 83; 43 (1991) 261 Nucl Phys B396 (1993) 161SP

kT,

q

p

p

SP

p

p

Sq

kT,π

Sq kT,π

Both effects can contribute to inclusive π0 AN

Need to go beyond inclusive π0 detection to separate them jets and direct photons, or π-π correlation in a jet

Asymmetry in hadrons in jets

Asymmetry in jet/photon production

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STARSTAR

Sampled 1.6 pb-1

Goal 3.8 pb-1

Integrated FMS FOM P2L (nb-1)

• Extend xF and pT range for forward single-spin asymmetries

• Separation of Collins and Sivers

Significant extension, but well short of what we had intended to achieve• Study direct photon asymmetries in forward direction

Probably not practical with the current limited data set

Transversely Polarized p+p FoM (P2L) at STAR

Using reported CNI

valuesOnly 43% of goal, after calibration

from jet

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STARSTAR

Run3-5 FPD

Inclusive 0 cross sections

AN for inclusive 0 production

FPD to FMS

RUN3 dAu =only one module (South)

At deuteron side (west)

Inclusive 0 cross sections in dAu and RdA

Forward-mid rapidity particle correlations

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STARSTAR FPD to FMS

47 x more area> Order of magnitude more luminosity

Run8 and beyond: FMS • FMS will provide full azimuthal

coverage for range 2.5 4.0

• broad acceptance in xF-p

T plane for

inclusive ,,,K,… production in p+p and d(p)+Au

• broad acceptance for and from forward jet pairs to probe low-x gluon density in p+p and d(p)+Au collisions

d Au

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STARSTAR

New FMS CalorimeterLead Glass From FNAL E831804 cells of 5.8cm5.8cm60cmSchott F2 lead glass

Loaded On a Rental Truck for Trip To BNL

Students prepare cells at test Lab at BNLTotal number of undergraduate students = 10Total number of graduate students = 5

Forward Meson Spectrometer (FMS)

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STARSTARForward Meson Spectrometer for Run8

Cockcroft-Walton HV bases with computer control through USB. Designed/built in house for FEU-84.

Cockcroft-Walton HV bases with computer control through USB. Designed/built in house for FEU-84.

Designed and built at Penn State UniversityDesigned and built at Penn State University

Small Cell PSU Type224 of 476Small Cell PSU Type224 of 476

Readout of 1264 channels of FMS provided by QT boards. Each board has

• 32 analog inputs

• 12-bit ADC / channel

• 5-bit TDC / channel

• Five FPGA for data and trigger

• Operates at 9.38 MHz and higher harmonics

• Produces 32 bits for each RHIC crossing for triggerDesigned and built at UC

Berkeley/SSL

QT board

First pi0 reconstruction of FMS events in Run8(Calibration is underway)

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STARSTAR Calibration is ongoing

Adjust gain for each detector by high tower sorted M1264 Mplots

Run 6 resolution of (M)/M~10%should be possible.

Need multiple iteration through the data since pion and photon energy get spread over several towers.

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STARSTAR

Calorimeter stable at level of ~1%.

Minimal run-by-run dependence in mass peak observed

Entire Run 8 data set should become quickly available with final calibration.

Calibration is ongoing

LED system : critical calibration tool MIT (LED optics)UC Berkeley/SSL (flasher boards)Texas / Protovino / BNL (assembly)SULI program (Stony Brook students) / BNL (control electronics)

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STARSTARFMS Summary and Future

• Forward Meson Spectrometer (FMS) is constructed & took data in run8!

Low-x physics (Can we see Gluon saturation? CGC?)

Separate Sivers from Collins“Jet-like” events, or pi0-pi0 Near and away side jet-pi0 correlations

Heavier mesons? Eta, Ks, J/psi…

• With Future running, Direct Photon + Jet to test “sign change” of Sivers function

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STARSTAR Heavy Flavor Physics in Run8

1. High-precision non-photonic electron• SVT+SSD removed ~ x10 reduction of BG • Staged L0 Trigger:• d+Au : ~90x statistics (run3)• p+p : ~30x statistics

2. ϒ• d+Au L2 trigger sampled 35 nb-1

• expected yield: ~ 240

• (separation of 3 S states unlikely)

3. D0

• d+Au Minimum bias dataset: 46 M events

• >2x statistics from previous d+Au run3

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STARSTAR

Largest Background source on inclusive electrons so far: Conversion electrons from SVT+SSD material

SVT/SSD removed (Run8)

Radiation length reduced ~1/10

Compare the e/h ratio to run3 corresponding results, we find inclusive electrons decrease to ~ 0.10

Less material decreases relative error by factor ~10

NP Electrons in STAR: Inclusive/Background

Removal of SVT+SSD : Impact on Heavy Flavor

Electron hadron ratio run8/run3

Charm production via NPE(EMC), D0, TOF (e and muon) are all consistent

Next crucial check: NPE with reduced material by order of magnitude

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STARSTAR

MinBias usable Events High Tower Integrated LuminosityGoal = 30 Mevts Goal = 30 nb-1

Recorded 46 Mevts153 % of goal

Sampled 36 pb-1

120 % of goal

92% have Vz 50 cm

MinBias Vertex (Z) Distribution

d+Au & pp integrated luminosity at STAR

dAu dAu

pp “slow” Luminosity (nb-1)

Goal 4.5 pb-1

Sampled 3.1 pb-1

69% of goal

pp

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STARSTAR Low Energy (9 GeV) Test Run

• Find Collisions

• Gain understanding of triggering issues

• Determine Luminosity

Luminosities

~ 1 to 3 x 1023 cm-2 s-1

Collisions rates

= x L

= (6 b)(1.5 x 1023 )

= ~ .9 Hz

Our present understanding of our trigger efficiency, and Angelika’s luminosity, agree very well (~ 20%)!

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STARSTARAu+Au @ √sNN=9 GeV: Preliminary Analysis

STAR preliminary

Uncorrected p⊥ spectra

STAR preliminary

Raw multiplicity

PID (dE/dx only)

STAR preliminary

Note: Plots should be taken only as illustrative of data quality and analysis capability

George Stephans’s Talk on Friday

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STARSTAR

Laser event (plus pileup)

DAQ1000 commissioning

• One sector of the TPC (1/24) instrumented with DAQ1000 electronics• Commissioned/integrated and took part of physics data taking by early run8• Routine operation at 250 Hz with TOF triggered events• Speed test: operated at 1 kHz with only 5-7% dead time (<<100 us/event)• On schedule to full implementation for run9

Replace full TPC readout chain to record full delivered luminosity

Dead-time ~ 0Data taking speed ~x10

Preliminary calibration shows dE/dx resolution and noise better than old electronics.

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STARSTAR Multi-gap Resistive Plate Chamber Time-of-Flight

Joint project between USA & China In detector research

1 tray in some of runs 2-75 trays in run 8 behind DAQ1000 ~75% in run 9100% in run 10 (Q2,FY09)-0.9<<0.9, 0<<223,000 ch (120 trays)

• Total TOF triggered events 76M for physics and calibration in p+p• Provide crucial information for pileup rejection• Preliminary calibration : 81ps (goal <100ps)

TOF+TPX from run8: • Non-photonic electron at low pT with low material • 25x statistics for PID spectra in p+p• >10x S/B ratio of Resonances () in p+p

Posters by Zebo Tang and Jin Fu

e

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STARSTAR

Roman pots installed east and west downstream of STAR (thanks, C-AD!) pp2pp data acquisition integrated into STAR trigger and DAQ systems Inserted Roman pots into the beam pipe during last 2 hours of p+p run

Observed pp2pp detector rates as expected No impact on background levels in STAR mid-rapidity detectors

Physics in Run 9

For the future: pp2pp @ STAR

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STARSTAR

System Trigger Goal Acquired

d+Au FMS 60/nb (reduced 30/nb)

49/pb

d+Au BEMC HT 30/nb 36/pb

d+Au MinBias 30M events 46M events

p+p FMS 9/pb 7.8/pb

p+p FMS P2L = 3.8/pb P2L = 1.6/pb

p+p BEMC HT 4.5/pb 3.1/pb

p+p MinBias Few k events Few k events(76M Events with TOF+TPX)

STAR Run8 Goals & Luminosity

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STARSTAR STAR Run8 SummaryMain Physics GoalsGluon saturation in relativistic heavy nucleiTransverse single spin asymmetries of forward 0

• (Transverse single spin asymmetries of gamma-jet) • (x-dependence of gluon polarization)Non-photonic electron, Upsilon and D-mesonsLow energy AuAu test run

Detector Upgrades:Commissioning of pp2ppCommissioning of FMSCommissioning of DAQ1000 All 3 used for PhysicsCommissioning of TOF

Short run didn’t allow us

to complete some of original goals

“Short” run8 was successfulExciting physics will be coming out

Documents

STAR Run-8 Achievement & Summary