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
13
3
B
N
pxdp
dE B
TN
F
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)