DY at STAR for decadal plan (run15-20) Akio Ogawa 1

DY 2 DY : ~7 x GeV Hadronic : ~30mb 10 6 Hadron & photon backgrounds Charm & bottom backgrounds Need >100 Billion hadronic events to simulate backgrounds PHENIX Muon Arm Eta = 1-2 DY Charm Bottom

STAR forward detectors 3 ≈ 6 L int spaghetti calorimeter 10cm x 10cm x 120 cm “cells” DX shell R ~ 60cm Proposed FHC ( for jet & lambda) FMS In open position x~50cm from beam No space for FHC near beam No space in front of FMS neither FTPC (to be removed next year)

DY signal Everything  >2 FMS closed (FHC cannot be placed due To DX magnet) FMS open (x=50cm) + FHC (x=60cm) pythia6.222, sqrts=500 DY process, 4M events/6.7E-05mb ~ 60/pb e+/e- energy>10GeV &  >2 x F >0.1 (25GeV) 4GeV < invariant mass < 10GeV Inv Mass EpTpT events 6512 events 1436 events (1/5 from closed) 4

(direct) b background pythia6.222, sqrts=500 DY process, 4M events / 6.7E-05mb ~ 60/pb B production, 300M events / 5.2E-03mb ~ 58/pb (Fragmentation b need 180B events / 30mb ~ 60/pb) FMS closed : small at high xF & high eta & mostly unlike sign Inv Mass E pTpT DY Direct B Direct B unlike Direct B like FMS closed e+/e- energy>10GeV &  >2 x F >0.1 (25GeV) 4GeV < invariant mass < 10GeV 5

(direct) b background Everything  >2 FMS closed FMS open (x=50cm) + FHC (x=60cm) Electron/position radius from beam at FMS DY Direct B e+/e- energy>10GeV &  >2 x F >0.1 (25GeV) 4GeV < invariant mass < 10GeV pythia6.222, sqrts=500 DY process, 4M events / 6.7E-05mb ~ 60/pb B production, 300M events / 5.2E-03mb ~ 58/pb (Fragmentation b need 180B events / 30mb ~ 60/pb) FMS closed : small at high xF & high eta & mostly unlike sign FMS opened + FHC : low xF & small eta (even smaller eta/phenix muon arm : b > DY) 6

High x F STAR needs High  > 4 coverage Additional e/Hadron separation – hadron suppression > 1/1000 per hadron Additional e/Gamma separation (incl gamma->e+e-) – gamma suppression > 1/1000 per gamma Forward tracking for charge like/unlike sign (?) Significant trigger upgrades – FMS with localized hadron & neutral veto Extension of west platform 7

STAR for decadal plan run )FFGT + Pre-Showers/Tracker/SMD + Shorter Ecal (PbW) + Hcal + removal of west platform 2) FFGT + Pre-showers/TRD/Tracker/SMD + FMS (fill 20cm x 20cm hole around beam pipe?) + extension of west platform 8

e/Hadron separation Trigger & offline – FMS (rarely measure full hadron energy) – FMS + FHC veto (1/10 – 1/1000 depends on energy) No space for ecal + hcal at eta=4 between DX & poletip holder – Pb Converter + Early-shower detector (~1/10) – Electron-ID like TRD or TR-Tracker (1/10 – 1/100) Offline – E(FMS)/p(tracking) Hard to measure p well at high xF with STAR magnet – FMS (or FMS-SMD) shower shape analysis (Need study) 9

EM calorimeter… 2500 PbWO crystals APD readout 1264 lead glass PMT readout hadron calorimeter… 1400 towers (Atlas) wheel/spoke support for DX and hadron calorimeter DX Wide Angle Hall Floor Concept for forward EM+hadron calorimeter at STAR Existing west side of Wide Angle Hall 3/27/10 10 HjC - H. Crawford/L. Bland

Cherenkov – 1GeV0.99 – 3GeV0.999 – air 1/n – hydrogen 1/n – 10GeV – 30GeV – 1GeV Transition Radiation Detector (TRD) – ALICE – AMS – HERMES Electron PID (hadron rejection) 11

TRD 12 1 layer (out of 20 layers) AMS TRD HERMES TRD Performance Electrons/positrons emit X-rays Which are detected in Xe/CO 2 gas detector, in addition to normal ionization

13

e/Gamma separation Trigger & offline – Neutral veto in Pre-Shower detector (~1/100) – Gamma->e+e- conversion in beam pipe Pre-shower with 2MIP/e+e- conversion pair veto (~1/100?) – Gamma->e+e- conversion in preshower (~1/2) Small radiation length in preshower (or 1 st tracking station) desired – Thin Pre-Shower detector with good resolution to do 0mip - 1mip - 2mip separation Offline – Reconstructing pi0 (and eta) and removing them in FMS ( ~ 1/10) – Tracking to resolve single electron to pair (? Need study) 14

15 Red foils: H/V traces Blue foils: Diag traces GEM based Pre-shower & Early-shower detectors Pre-shower 0.3mm – 0.9mm pitch 55k channels ~2RL Pb Converter Early-shower 2mm -3mm pitch 11k channel Total 66k channels Carl Gagliardi

Charge like/unlike sign Charge like/unlike sign separation needed? If so, STAR solenoid enough? Or need forward dipole magnet? Tracking – FGT with small R + a couple more rings ? – Another tracker at FMS (pre-shower or SMD) ? Momentum resolution for E/p ? c/b tag ? 16

STAR Magnetic Field Radial and Azimuthal fields impart impulses in the Φ direction and partially cancel Chris QM09 talk : 17

Run8 FMS-FTPC (Jim Drachenberg) ΔΦ = 0.1 Δz/p z (Δz=2.5m) = 0.25 radian / GeV For 10GeV at FMS x=20cm = 0.5cm x=40cm = 1.0cm x=80cm = 2.0cm For 50GeV at FMS x=20cm = 0.1cm x=40cm = 0.2cm x=80cm = 0.4cm FTPC+FMS have done charge separation with STAR magnet at 2.8<  <3.8 E ~ 10GeV 18

19 (FTPC)

FGT extension? 20  4  3  2 J. Balewski/MIT

Dipole Analysis Magnet Concept Present RHIC Interaction Regions Conceptual Plan to Allow DXA reduce field strengths in D0,DX move DX towards IP Forward DY Interaction Region if charge sign required DXA used for beams and for DY daughters 3/27/10 21 HjC - H. Crawford/L. Bland

STAR for decadal plan run )FFGT + Pre-Showers/Tracker/SMD + Shorter Ecal (PbW) + Hcal + removal of west platfrom~ 10 M$ ?? 2) FFGT + Pre-showers/TRD/Tracker/SMD + FMS (fill 20cm x 20cm hole around beam pipe?) + extension of west platform ~ 5M$ ?? 22

backup 23

Some documents Updated FHC proposal Hank's FHC talk at STAR upgrade meeting DY paper (2007) 24

25 Simple QED example: DIS: attractive Drell-Yan: repulsive Same in QCD: As a result: Attractive vs Repulsive Sivers Effects Unique Prediction of Gauge Theory !

x Sivers Amplitude 0 0 HERMES Sivers ResultsRHIC II Drell Yan Projections Markus Diefenthaler DIS Workshop Műnchen, April 2007 DOE HP13 milestone “Test unique QCD predictions for relations between single-transverse spin phenomena in p+p scattering and those observed in deep-inelastic lepton scattering” with an estimated completion of 2015” Attractive vs Repulsive Sivers Effects

27

28