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a FO rward CAL orimeter

a FO rward CAL orimeter. Overview. Richard Seto Winter Workshop on Nuclear Dynamics Feb 7, 2009. NSAC milestones – Physics Goals. pA physics – nuclear gluon pdf.  G. -Jet AuAu. transverse spin phenomena. Look for saturation effects at low x

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a FO rward CAL orimeter

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  1. a FOrward CALorimeter Overview Richard Seto Winter Workshop on Nuclear Dynamics Feb 7, 2009

  2. NSAC milestones – Physics Goals pA physics – nuclear gluon pdf  G -Jet AuAu transverse spin phenomena

  3. Look for saturation effects at low x Measure initial state of Heavy Ion Collision measure gluon PDF’s in nuclei! (DM8) x pA physics – nuclear gluon pdf Saturation at low x Nuclear Gluon PDF’s : DM8 xG(x) direct  jets –x resolution forward η(low-x)

  4. Longitudinal Spin G, g(x) : HP12 • What is the gluon contribution to the proton spin. Is it at low-x? • Phenix and STAR have put constraints on G

  5. x Longitudinal Spin G, g(x) : HP12 DSSV finds • g(x) very small at medium x (even compared to GRSV or DNS) • best fit has a node at x ~ 0.1 • huge uncertainties at small x Current data is sensitive to G for xgluon= 0.020.3 EXTEND MEASUREMENTS TO LOW x! Forward Measure x RHIC range 0.05· x · 0.2 small-x 0.001· x · 0.05 direct  jets –x resolution forward η(low-x) 0 0

  6. use -jet to measure Sivers Use 0 in jet to measure Collins determination of the process dependence of the Sivers effect in g+jet events So what does Sivers tell us about orbital angular momentum? Major new Thrust Transverse Spin Phenomena: HP13 Sivers direct  -jet 0 forward η(low-x) large η coverage

  7. Study the medium via long range correlations with jets are these correlations from a response by the medium? “jet” “ridge” STAR Preliminary Correlations with jets in heavy Ion collisions: DM10 for example ? leading EM shower EM - shower large η coverage Jet correlations in AuAu

  8. direct  and electromagnetic showers jet angles to obtain x2 0 s forward  to reach low-x has large  coverage To meet these goals we must have a detector that measures: now what do we build?

  9. Central Arms ||<0.3 Tracking PbSc/PbGl(EMC) PID VTX to come Muon arms 1.1<||<2.4 magnet tracking -ID FVTX to come Schematic of PHENIX central magnet MPC 3<||<4 calorimetry

  10. Perfect space for FOCAL! (but tight!) 40 cm from Vertex FOCAL • EM bricks • 14 HAD bricks • HAD behind EM 20 cm of space nosecone

  11. FOCAL Requirements • Ability to measure photons and π0’s to 30 GeV • Energy resolution < 25%/E • Compact (20 cm depth) • Ability to identify EM/hadronic activity • Jet angular measurement • High granularity ~ similar to central arms • small mollier radius ~1.4 cm • large acceptance – rapidity coverage x2 ~ 0.001 • Densest calorimeter -> Si W We wanted large  coverage what sort of coverage if we put a detector where the nosecones are?

  12. FOCAL FOCAL Muon tracking Muon tracking VTX & FVTX FOCAL a large acceptance calorimeter tracking EMC 0 f coverage 2p tracking EMC MPC MPC -3 -2 -1 0 1 2 3 rapidity What’s missing? FORward CALorimetery

  13. reach in x2 for g(x) and GA(x) log(x2) EMC+VTX EMC+VTX+FOCAL EMC+VTX+FOCAL+MPC X2  10-3

  14. FOCAL Design

  15. Overall Detector – stack the bricks “brick” supertower 6cm 17 cm 6cm 85 cm Note this ledge may not be in the final design

  16. Pads Silicon Design Design Tungsten-Silicon Pads: 21 layers • 535 m silicon • 16 cells: 15.5mmx15.5mm X and Y Strips: 4 layers • x-y high resolution strip planes • 128 strips: 6.2cmx0.5mm γ/π0 Discriminator=EM0 segments= EM1 EM2 Supertower Particle Direction 6cm 4 planes of x-y “strips” (8 physical planes) 4 mm W Silicon “pads”

  17. Vital statistics • EM0= /0, EM1, EM2 segments • ~17 cm in length • 22 X0 ~ 0.9 • Strips – read out by SVX-4 • 8 layer *128 strips=1024 strips/super-tower • 1024 strips/super-tower*160 super-towers/side = 163,840 strips/side • 163840 strips/side (1detector/128 strips) = 1280 Strip Detectors/side • 163,840 strips /(128 channels/chip)= 1280 chips/side • Pads – read out by ADC– 3 longitudinal readouts • 160 supertowers/side*21 detectors/supertower= • 3360 Si pad detectors/side • 3360 detector*16channels/detector= 53760 pads/side • readout channels (pads) • 160 supe-rtowers/side *16 pads/tower*3 towers =7680 readouts/side • Bricks • 2x4 supertowers: 4 • 2x6 supertowers: 6 • 2x7 supertowers: 4

  18. Detection – how it works Some detector performance examples

  19. Status of simulations • Stand alone done w/ GEANT3/G4 to study • /0 separation, single track 0 (G4) • EM shower energy/angle resolutions (G4) • Full PISA • jet resolution (G3/PISA) • 2 track 0 (G3/PISA) • Several levels • Statistical errors, backgrounds, resolutions folded into Pythia level calculations • Full PISA simulation using old configuration • Transverse spin physics – task force formed – simulations in progress (early step is to put models etc into simulations) *PISA – PHENIX Geant3 simulation

  20. vertex It’s a tracking device A 10 GeV photon “track” EM2 EM0 EM1 Pixel-like tracking: 3 layers + vertex Each “hit” is the center of gravity of the cluster in the segment Iterative pattern recognition algorithm uses a parameterization of the shower shape for energy sharing among clusters in a segment and among tracks in the calorimeter.

  21. Energy Resolution (Geant4) New Geometry Excludes Strips no sampling fraction correction 0.00+0.20/√E adequate: we wanted ~ 0.25/√E

  22. /0 identification: pp 2 track 0 pT<5 GeV E=6-10 GeV pt=2.-2.5 y=1-1.5 pt=1.-1.5 y=1-1.5 pt=4.-4.5 y=1-1.5 pt=1.5-2.0 y=1.5-2.0 pt=0.5-1.0 y=2-2.5 pt=0.5-1.0 y=1.5-2.0

  23. /0 identification:Single track /0 50 GeV pi0 • for pt>5 GeV • showers overlap • use x/y + vertex to get opening angle • Energy from Calorimeter • Energy Asymmetry – assume 50-50 split as a first algorithm X-view 4-x, 2x Y-view 4-y, 3y invariant mass

  24. 10 GeV h~1.65 (Geant4-pp events) Assumed g region Assumed p0 region  0 • /0 identification: single track /0 • tested at various energies and angles, so far at pp multiplicities Fake g reconstruction: 20% Real p0 reconstruction: 50-60% Real g reconstruction: ~ 60% Fake p0 reconstruction ~ 5%

  25. Longitudinal Spin G, g(x) : HP12 GSC, Response + Background ALL 150/pb, P=0.7 RHIC region FOCAL Direct Gamma ALL next step: use -jet to constrain x

  26. GSC DSSV Selecting x with rapidity cuts 0 0 • Use 0 as a stand in for jets and do a correlation • require 1st 0 pT>2.5 GeV, =1-3 (into focal) • Choose 2nd 0 to be opposite side in  and  to go to low x2 log(x2) (2nd 0) Longitudinal Spin Goal

  27. q Compton g q  q Annihilation g q unknown “Direct” Constraint of G(x) in Nuclei:DM8 Valence Gluon Sea Eskola et al, JHEP0807:102,2008 hep-ph/0802.0139 • G(x) in nuclei almost unconstrained at low x • Proposal: Measure -jet in d+Au collisions to extract G(x) in nuclei

  28. x2~ resolution 15% Resolutions • EM shower • energy – 20%/E • angular – 6mr • Jet angular resolution • 60 mr @ pt=20 GeV jet angular resolution pT Full PISA simulation

  29. Expected Error for GA(x)/Gp(x) :DM8 pT jet>4 GeV, ptgamma>2 d+Au: Ldt = 0.45 pb -1 x 0.25 eff p+p: Ldt = 240 pb-1 x 0.25 eff G(x)Au/G(x)p Current uncertainty Log(x2) • Possibility for a dramatic improvement in understanding of G(x) in nuclei • Impact is widespread • Errors are statistical only

  30. “jet” leading particle hadrons leading particle suppressed “ridge” hadrons q q q q STAR Preliminary hadrons hadrons leading particle leading particle suppressed Studying the medium through jet “tomography”DM10 pTtrig>2.5 GeV/c, pTassoc > 20 MeV/c, Au+Au 0-30% jet ridge E. Wenger (PHOBOS), QM2008

  31. Jet correlation studies with the FoCalDM10 • Need • higher-pT triggers, • Extended  reach • large  • How: • trigger on high-energy g in FoCal • study associated particles in central and muon arms • What: • Extended h reach and Dh range (~6) • Study particle composition of correlated particles using central/muon arm PID detectors including photons • Heavy-quark studies via leptons in central/muon arms

  32. Parameterize background by studying average energy deposited in the detector (E) and its fluctuations (RMS) Study efficiency and contamination for set values of Nσ E ERMS Strategy: /0 trigger eff, AuAu b=3.2 fm =[1.,1.5] Ecut> ~15 GeV background assuming pp high pt rates S:B~10:1 /0 trigger eff high pT em shower embedded in hijing

  33. Conclusion • We want to address the following NSAC milestones • measure G at low-x to see if the gluon contributes to the proton spin • measure the nuclear gluon pdf’s • to study the effects of transverse spin and its connection to the orbital angular momentum of the constituents of the proton • Study long range correlations between jets and secondary particles as a means to understand the medium created in heavy ion collisions at RHIC • These goals can addressed by calorimeter which • can identify and measure s and 0 • can measure the jet angular resolution and together with the information from the  can lead to a reasonable measurement of x2 • has large rapidity coverage and can probe x2  10-3 • We now have a have design • Prototype in April

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