N. Poljak, 01.13.2006. 1FPD++

N. Poljak, U. of Zagreb

N. Poljak, 01.13.2006. 2

TPC: -1.0 < < 1.0

FTPC: 2.8 < < 3.8

BBC : 2.2 < < 5.0

EEMC:1 < < 2

BEMC:-1 < < 1

FPD: || ~ 4.0 & ~3.7

Layout

N. Poljak, 01.13.2006. 3

pQCD Physics results

Unlike at lower energies, the inclusive differential cross section for pion production at 200 GeV is consistent with NLO pQCD calculations at 3.3<η <4.0

As η increases, systematics regarding the comparison with NLO pQCD calculations begin to emerge. The data at low pT are more consistent with the Kretzer set of fragmentation functions.

N. Poljak, 01.13.2006. 4

AN results

J. Adams et al. (STAR), Phys. Rev. Lett. 92 (2004) 171801

AN grows with increasing xF for values larger then 0.35

Results from run2 don’t yet discriminate between different dynamics

First result for the AN(pT) was obtained using combined statistics from run3 and run5. There is evidence that the analyzing power at xF >0.4 decreases with increasing pT

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Run 2 Published Result.Run 2 Published Result. Run 3 Preliminary Result.Run 3 Preliminary Result. -More Forward angles.-More Forward angles. -FPD Detectors.-FPD Detectors.

Run 3 Preliminary Run 3 Preliminary Backward Angle Data.Backward Angle Data. -No significant Asymmetry -No significant Asymmetry seen.seen. ( Presented at Spin 2004: hep-ex/0502040)

Run 3 + Run 5 Preliminary Run 3 + Run 5 Preliminary <<>=3.7,4.0>=3.7,4.0(Presented SPIN 2005 Dubna Sept 27-Oct (Presented SPIN 2005 Dubna Sept 27-Oct 1, Absolute polarization still preliminary)1, Absolute polarization still preliminary)

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Run-6 FPD++

FPD++ Physics for Run6

Run-5 FPD

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Basic physics GoalsIdeas to be tested using FPD++ in Run6

• Prototype for FMS (RUN7)• Discriminate dynamical origin of the forward AN

– Measurement of jetlike events and AN for those• Similar to FPD (left, right) but with larger active area• Measure shape of forward jet

– Measure direct photons cross section, possibly AN --- separation of and direct gamma

• Continue the study of asymmetry in pp• other

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Jet spin asymmetry

• Is the single spin asymmetry observed for also present for the jet the comes from?

• Answer discriminates between Sivers and Collins contributions

• Trigger on energy in small cells, reconstruct and measure the energy in the entire FPD++

• Average over the Collins angle and define a new xF for the event, then see if analyzing power increases with xF

Expect that jet-like events are Expect that jet-like events are ~~15% of 15% of events events

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Where do decay partners go?

• Gain sensitivity to direct photons by making sure we have high probability to catch decay partners• This means we need dynamic range, because photon energies get low (~0.25 GeV), and sufficient area (typical opening angles few degrees at our ranges).

di-photon parameters

z = |E1-E2|/(E1+E2)

= opening angle

Mm = 0.135 GeV/c2 ()

Mm=0.548 GeV/c2 ()

1

2

max min2 2

1 2

for candidate photon with E ,

1, gives the energy of second photon

1

1 1sin , sin give max and min opening angle 2 2 1 2

m m

m

E

zE E

z

zM c M cE z E E

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Sample decays on FPD++

The FPD++ is much closer to FPD then FMS will be. We can mimic the FPD

trigger and search for the second around the first

With FPD++ module size and electronic dynamic range, the yellow area

marks where we have 95% probability of detecting second photon from

decay

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Status report

• Calorimeter cells for free thanks to FNAL / U.Col. and Protvino

• Cells were refurbished and tested in physics

• South enclosure in place on STAR west platform, readout in place

• cell by cell IN SITU tests and cables connected

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To do list

Put the north module in place

Conect the readout electronics and test all readout

Finalize the readout and trigger details

Perform measurements with 15/pb delivered integrated

luminosity

(for 4-5 measurement of AN in jet like events)

RUN 6RUN 6 RUN 7RUN 7

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BACKUP SLIDES

N. Poljak, 01.13.2006. 14Planned FMS WallPlanned FMS Wall

FMS …. To be installed for RUN7

• Expanding the eta coverage -1<<4

• Measurement of the same side correlations

• Opposite side correlated pions (dijets) – Sivers effect– d-Au (Gluon saturation

in Nuclei)• Other future objectives

– Forward Lepton pairs– Charm– Drell Yan

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ReconstructionFPD (Forward Pion Detector) proved we can reconstruct forward in

all (pp, dAu, CuCu) environments

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Separated xF and pT dependence

65

13

3

BN

pxdpdE B

TN

F

Similar to ISR analysisJ. Singh, et al Nucl. Phys. B140 (1978) 189.

Shows the data consistency

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AN(pT) in run3+run5 at √s=200 GeV• Combined statistics Combined statistics

from run3 and run5 from run3 and run5 allowed to distinguish allowed to distinguish nonzero effect in Anonzero effect in ANN(p(pTT) ) plotplot

• There is an evidence There is an evidence that analyzing power at that analyzing power at xxFF>0.4 decreases with >0.4 decreases with increasing pincreasing pTT

• Theoretical prediction’s Theoretical prediction’s needed (for constraint needed (for constraint on Sivers function).on Sivers function).

Online calibration of CNI polarimeter

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How to detect direct photons?We have good sensitivity to both photons in decay of known particles, so that

unpaired photons become candidates for being “direct”.

π0 M=0.135 GeV BR=98.8% K0 π0π0 0.497 31% 0.547 39% π0 0.782 8.9% ’ 0.958 2.1%

Other decay modes yield more photons with less Q

Background simulations underway

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Proposed readout