DY at STAR
for decadal plan (run15-20)
Akio Ogawa
1
DY
DY : ~7 x 10-5 mb
@ 500GeV
106
Hadronic : ~30mb
Hadron & photon backgrounds
Charm & bottom backgrounds
Need >100 Billion hadronic events to
simulate backgrounds
PHENIX Muon Arm
Eta = 1-2
DY
Charm Bottom
http://spin.riken.bnl.gov/rsc/write-up/dy_final.pdf
2
STAR forward detectors
FTPC (to be removed next year)
Proposed FHC
(for jet & lambda)
≈ 6 Lint spaghetti calorimeter
10cm x 10cm x 120 cm “cells”
DX shell R ~ 60cm
FMS
In open position
x~50cm from beam
No space for FHC near beam
No space in front of FMS neither
3
DY signal
Everything h>2
14799 events
pythia6.222, p+p @ sqrts=500
DY process, 4M events/6.7E-05mb ~ 60/pb
e+/e- energy>10GeV & h>2
xF>0.1 (25GeV)
4GeV < invariant mass < 10GeV
FMS closed
(FHC cannot
be placed due
To DX magnet)
6512 events
FMS open (x=50cm)
+ FHC (x=60cm)
1436 events
(1/5 from closed)
Inv Mass
E
pT
4
(direct) b background
pythia6.222, p+p @ 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)
e+/e- energy>10GeV & h>2
xF>0.1 (25GeV)
4GeV < invariant mass < 10GeV
FMS closed
DY
Direct B
Direct B unlike
Direct B like
Inv Mass
E
pT
FMS closed : small at high xF & high eta & mostly unlike sign
5
(direct) b background
pythia6.222, p+p @ 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)
Everything h>2
FMS closed
e+/e- energy>10GeV & h>2
xF>0.1 (25GeV)
4GeV < invariant mass < 10GeV
FMS open (x=50cm)
+ FHC (x=60cm)
DY
Direct B
Electron/position radius from beam at FMS
FMS closed : small at high xF & high eta & mostly unlike sign
FMS opened + FHC : significant @ low xF & small eta
(even smaller eta/phenix muon arm : b > DY)
6
High xF DY @ STAR needs
• High h > 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
DY @ STAR for decadal plan
run15-20
1) 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
H. Crawford/L. Bland
EM calorimeter…
Concept for
forward
EM+hadron
calorimeter at
STAR
• 2500 PbWO crystals
• APD readout
• 1264 lead glass
• PMT readout
Existing west side of
Wide Angle Hall
wheel/spoke
support for DX
and hadron
calorimeter
DX
hadron calorimeter…
• 1400 towers (Atlas)
Wide Angle Hall Floor
3/27/10
HjC - STAR@BNL
10
Electron PID (hadron rejection)
• Cherenkov
–
–
–
–
–
–
–
Beta(pion) @ 1GeV
Beta(pion) @ 3GeV
air 1/n
hydrogen 1/n
Beta(pion) @ 10GeV
Beta(pion) @ 30GeV
Beta(electron) @ 1GeV
0.99
0.999
0.99970
0.99986
0.9999
0.99999
0.9999999
• Transition Radiation Detector (TRD)
– ALICE
http://www-alice.gsi.de/trd/transp/andronic07.pdf
– AMS
http://cyclo.mit.edu/~bmonreal/trd.html
– HERMES http://hermes.desy.de/notes/pub/96-LIB/thiessen.96.028.ps.gz
11
TRD
1 layer (out of 20 layers) AMS TRD
http://cyclo.mit.edu/~bmonreal/trd.html
HERMES TRD Performance
http://hermes.desy.de/notes/pub/96-LIB/thiessen.96.028.ps.gz
Electrons/positrons emit X-rays
Which are detected in Xe/CO2 gas
detector, in addition to normal ionization
12
http://www-alice.gsi.de/trd/transp/andronic07.pdf
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 1st 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
GEM based Pre-shower & Early-shower detectors
Red foils:
H/V traces
Blue foils:
Diag traces
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
Chris QM09 talk : http://drupal.star.bnl.gov/STAR/files/QM2009_Perkins_v5_0.ppt
•
Radial and Azimuthal fields impart impulses in the Φ direction and partially cancel
 =
c(  Bzdr 
 B dz)
r
Pr
c
P
3.5 Pr
(0.5T r 4m 
0.1T 1m)
Pr
Pz
0.4 Pz
0.6  0.26[radian] 0.34[radian]


Pz[GeV ]
Pz[GeV ]

17
Run8 FMS-FTPC (Jim Drachenberg)
http://www.star.bnl.gov/protected/spin/drach/Run8FMS/FMS-FTPC_correlation/
ΔΦ = 0.1 Δz/pz
(Δz=2.5m)
= 0.25 radian / GeV
For 10GeV at y=0 @ FMS
Δy @ x=20cm = 0.5cm
Δy @ x=40cm = 1.0cm
Δy @ x=80cm = 2.0cm
For 50GeV at y=0 @ FMS
Δy @ x=20cm = 0.1cm
Δy @ x=40cm = 0.2cm
Δy @ x=80cm = 0.4cm
FTPC+FMS have done charge
separation with STAR magnet at
2.8<h<3.8
E ~ 10GeV
18
(FTPC)
19
J. Balewski/MIT
FGT extension?
h=2
h=3
h=4
20
H. Crawford/L. Bland
Dipole Analysis Magnet Concept
Present
InteractionRegion
Regions
ForwardRHIC
DY Interaction
if charge sign required
Conceptual Plan to Allow DXA
• reduce field strengths in D0,DX
• move DX towards IP
• DXA used for beams and for DY daughters
3/27/10
HjC - STAR@BNL
21
DY @ STAR for decadal plan
run15-20
1) 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
http://hena.lbl.gov/FMS/docs/hcal_proposal_update_091001.pdf
• Hank's FHC talk at STAR upgrade meeting
http://drupal.star.bnl.gov/STAR/system/files/FHC_091217.pdf
• DY paper (2007)
http://spin.riken.bnl.gov/rsc/write-up/dy_final.pdf
24
Attractive vs Repulsive Sivers Effects
Unique Prediction of Gauge Theory !
Simple QED
example:
DIS: attractive
Drell-Yan: repulsive
Same in QCD:
As a result:
25
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”
Sivers Amplitude
HERMES Sivers Results
RHIC II Drell Yan Projections
0
0
Markus Diefenthaler
DIS Workshop
Műnchen, April 2007
0.1
0.2
0.3 x
Attractive vs Repulsive Sivers Effects
26
27
28