STARSTAR W.B. Christie, BNL

RHIC Coordination meeting

January 17, 2006Outline

Summary of STAR’s request for Run 6

Physics objectives

Comments on Sam’s Draft Run Plan

STARSTARSTAR Run Plan for 20 week RHIC Run

Star RUN request is for polarized pp beams, at √s = 200 GeV, for all Physics running. A “mid-point projection” for integrated luminosity for ~11.5 wks gives ~ 45 pb-1 delivered → gives 15 pb-1 sampled at STAR

Note: exact breakdown of time, and order, of transverse (~ 5 pb-1 sampled) and longitudinally (~ 10 pb -1sampled) polarized beams to be finalized. For now, STAR would like to reserve the possibility to change choice of spin orientation up to 2 times during the √s = 200 GeV running period.

STAR also supports a limited period of “500 GeV” Collider commissioning. Limited meaning sufficient to confirm work done since last “500 GeV” commissioning (e.g., ring re-alignment), and make next step forward. Hopefully this means something on the order of 2 to 3 days.

STARSTARJet (Run5 data) under analysis

2005 Actual statistics

Jet yields from run5 data for

Jet-patch trigger

high tower trigger

And actual statistics for ALL

~2.4M events

~0.9M events

STARSTARInclusive Jet Production – STAR Run 6 Projections

Measurement should be sensitive at standard GRSV model prediction level with jet patch trigger!

STARSTARBasic 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

STARSTAR

Run-6 FPD++

FPD++ Physics for Run6

Run-5 FPD

STARSTAR

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 (Presented SPIN 2005 Dubna Sept 27-Oct 1, Absolute polarization still 27-Oct 1, Absolute polarization still preliminary)preliminary)

~ 6 from 0 for xF>0.4

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Back-to-back di-jets: access to gluon Sivers function

Measurement should be sensitive at level of model predictions

Measurements near mid-rapidity with STAR – search for spin-dependent transverse motion preferences inside proton (related to Lorbit) via predicted spin-dependent deviation from back-to-back alignment

> 7 GeV trigger jet

> 4 GeV away side jet

STARSTARA qualitative advance in understanding the role of orbital motion in the structure of the proton

Statistical error projection for AN for inclusive π0 production as function of pT at fixed xF during Run 6, together with two theory predictions. These projections assume 10 pb-1 with 50% polarization and the acceptance of the FPD++.

STARSTARQuality Factors for Run VI Longitudinal Studies

Measurement Increase from FOM Increase from Detector Improvements

Increase from Trigger Improvements

Bottom Line

ALL of jets x 5 at high ET compared to Run 5

x 3 at high ET due to completion of the BEMC

First measurement to distinguish

between favored models of gluon polarization

ALL of π0 in the EEMC x 5 compared to Run 5 x 1.3 from shielding in tunnel

Significant enrichment

at low pT from L2 trigger

Meaningful measurements in

multiple channels

ALL of π0 in the BEMC x 5 compared to Run 5 x 2 from completion of BEMC

Significant enrichment

at low pT from L2 trigger

Meaningful measurements in

multiple channels

ALL of di-jets x 5 at high ET compared to Run 5

x 9 at high ET (x 3 at low ET) due to completion of

the BEMC

Enrichment at low ET

from L2 triggerFirst measurement that is sensitive to x dependence

of ΔG/G

ALL of direct photons at mid-rapidity

x 5 compared to Run 5 x 1.5 from completion of BEMC

Increased efficiency near threshold from

L2 trigger

>100K direct photons for 10

pb-1 Sensitive to the sign of ΔG

ALL of direct photons at forward rapidity

FPD++ will allow isolation cuts for the first time

100K direct photons for 10 pb-1 Sensitive to gluon polarization at low x

γ+jet coincidences Optimize trigger and analysis

algorithms before Run 7

STARSTAR

Measurement Increase from FOM Increase from Detector Improvements

Increase from Trigger Improvements

Bottom Line

AN of π0 at forward rapidity

x 10 compared to previous measurements

FPD++ acceptance ~9 times that of

the FPD

x 2 by de-coupling FPD++ fast and slow read-out

Are we seeing quark orbital

motion and/or transversity?

AN of direct photons at forward rapidity

FPD++ will allow isolation cuts for

the first time

x 2 by de-coupling FPD++ fast and slow read-out

100K direct photons for 10 pb-1

Direct measure of the quark

Sivers function

AN for jets at forward rapidity and asymmetry of forward jets about thrust axis

FPD++ will encompass the jet cone for the first time

x 2 by de-coupling FPD++ fast and slow read-out

Direct sensitivities to the Sivers

(jet AN at 4~5σ) vs. Collins (jet

anisotropy) effects

AN for back-to-back di-jet opening angle

x 4 when compared to previous sensitivity estimates due to di-jet selection by L2

trigger

Measure gluon Sivers function

Quality Factors for Run VI Transverse Studies

STARSTAR• RHIC pp performance: Luminosity

Fischer/Roser projections

11 weeks of physics

running:

STAR delivered

luminosity: 45pb-1 STAR recorded

luminosity: 15pb-1

Allowing for 5pb-1 of

transverse and 10pb-1

of longitudinal mode

running

STARSTARSTAR Run 6 Physics Summary

Longitudinal running

Significant result for ALL via inclusive jets

π0 ALL in B/EEMC

Initial sample of di-jets and direct gamma (for ultimate goal of ΔG(x))

Transverse running

Significant result for forward rapidity Sivers via FPD++

Significant result for Sivers function for mid-rapidity di-jets

STARSTARComments on Sam’s Draft Run Plan for Run 6

• STAR would like to maximize the 200 GeV physics running- If less than 45 pb-1 delivered luminosity, we would likely lose either the transverse of longitudinal physics goals.

- Have well planned, necessary 500 GeV Collider commissioning.

• STAR would like to reserve the possibility to change the polarization direction up to 2 times during the 200 GeV physics running.

STARSTAR

BACKUP & ALTERNATIVE

SLIDES

STARSTARInclusive Jets (Panic 05):Run4 cross section (Mike Miller)

Run 3 and 4 combined ALL

(Joanna Kiryluk)

*) Predictions: B.Jager et.al, Phys.Rev.D70(2004) 034010

STARSTARNew Run 6 STAR Detector Additions

Barrel EM Calorimeter (BEMC)

full east side tower readout and trigger (e.g., full barrel!)

east side SMD readout (and re-worked west)

add east preshower readout (continue w/ full commissioning)

Utilize L2 trigger (in addition to increased L0 selectivity)

di-jet trigger

more efficient πo and γ trigger

Shielding for STAR IR in both east and west tunnels

FPD (forward pion detector) → FPD ++

STARSTAR

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

STARSTARAN 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

STARSTARpQCD 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.

STARSTARJet 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

STARSTARSample 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

STARSTARTo 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

STARSTARStatus 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

STARSTARInclusive Jet Production – STAR Run 6 Projections

STARSTAR• RHIC pp performance: Polarization

RHIC polarization in Run 5

Assumption for projections: 50%

STARSTAR

D0

D0

Shielding added in Tunnels at STAR

DX

East to STAR IRWest from STAR IR

STARSTARWhere 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 2m m

m

E

zE E

z

zM c M c

E z E E

STARSTAR

Planned 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

STARSTARReconstructionFPD (Forward Pion Detector) proved we can reconstruct forward in all (pp, dAu, CuCu) environments

STARSTARSeparated xF and pT dependence

6

5

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3

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

Shows the data consistency

STARSTARAN(pT) in run3+run5 at √s=200 GeV

• Combined statistics from run3 and run5 allowed Combined statistics from run3 and run5 allowed to distinguish nonzero effect in Ato distinguish nonzero effect in ANN(p(pTT) plot ) plot

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

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

Online calibration of CNI polarimeter

STARSTARHow 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

STARSTARProposed readout

STARSTARSTAR RUN 6 plans

• Original STAR BUR 6 presented to PAC: 20 weeks physics running

– Physics goals:

• Transverse program (Recorded luminosity 10pb-1): Role of transversity and parton orbital motion in

forward single-spin asymmetries - Sivers effect in di-jet production

• Longitudinal program (Recorded luminosity 20pb-1): Gluon polarization measurements

• STAR plans with foreseen 18 cryo week run: 13 weeks physics running

– STAR is asking for 200GeV physics running only

– Physics goals: Assume 11 weeks of 200GeV physics running

• Transverse program:

• Longitudinal program::

Clear progress of above BUR physics goals

1. Commissioning

period: Longitudinal

mode

2. Collect 5pb-1 of

transverse data

3. Return to

longitudinal data

mode (10 pb-1)