phenix local polarimeter @ run9
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PHENIX local polarimeter @ RUN9
2009/02/27 @ RSC meeting
1
Took data @ Fill#10228
• 56*56 bunch collision
• Polarization @ CNI monitor : 20-30%
• Sample selection– Collected by BBCLL1&(ZDCN|S)
–Measured energy @ ZDC > 40 GeV.
– SMD hit at least 2 columns to determine the position.
Cut parameters are very preliminary 2
First results from RUN9(First measurement at 500 GeV!)
BBCLL1&(ZDCN|S) ~20 M evtsBy sqrt formula
Blue forward
Blue backward
Yellow forward
Yellow backward
3
Local pol. scalers
• We can measure spin condition bunch-by-bunch
• We can measure it online.– So far we took LP trigger with 200 Hz at
physics run, and analyze it after run.
New!
SMD scintillators for x (7 scnti.)
LEFT RIGHT
Bottom
TOP
SMD scintillators for y (8 scinti.)
Hit patterns are sent by fibers
Make hit pattern by TDC in FEM(with high threshold) ZDC
LL1
Make scaler in ZDC LL1 bord4*2*120 channels 20 bits in each!
Local pol. scaler is developing by : Cheng-Yi Chi, Ed Desmond, Yuji Goto, John Haggerty, John Lajoie and Manabu Togawa
4
Scaler counts
- 10 mins data
- SMD threshold has no optimization. Just apply high threshold for this data.
- Small BG can be confirmed by unfilled bunch
5
LP scaler can see asymmetry too!
Significant asymmetry in LR only and we got it bunch-by-bunch! This is just 10 minutes data. We need to check stability.
Crossing#
(NL-N
R)/
(NL+
NR)
(NB-N
T)/
(NB+
NT)
Measured @ SOUTH LR Measured @ NORTH LR
Measured @ SOUTH TB Measured @ NORTH TB
6
Fill#10228
2009/02/27 (28*28 bunch collision)
Crossing#
(NL-N
R)/
(NL+
NR)
(NB-N
T)/
(NB+
NT)
Measured @ SOUTH LR Measured @ NORTH LR
Measured @ SOUTH TB Measured @ NORTH TB
7
Fill#10260
backup
8
Setup
Collision point
BBC
1800 cm
Schematic view from simulation. - GEANT3 (Geisha) - From the pythia simulation, Main backgrounds are photon and proton.
ZDC(Zero Degree Calorimeter)
3 module150X0 5.1λI
SMD
1 ZDC
SMD (Shower Max Detector)
Neutron position can be decided by centroid method.
10*10cm ±2.8 mrad
Detector asymmetry
10
Raw
asy
mm
etry Blue forward
Blue backward
Yellow forward
Yellow backward
Luminosity asymmetry~ 0.5-1.5%
Detector asymmetries are up to 50%, but it is cancelled according to backward asymmetry.
ZDC energy distribution with high threshold cut for SMD (in ZDCN|S sample @ RUN5 data)
• SMD threshold corresponds to 20 MIP– With high SMD cut can be help to select neutron sample.
• BG1 : photon will stop at 1st module; not hit SMD.• BG2 : proton event is only distributed low energy region. 11
NORTHSOUTH
Bottom cut Top cut
Left cut Right cut
Bottom cut Top cut
Left cut Right cut
Measured energy in ZDC (GeV)
70 GeV
Raw asymmetry for Fill#10228
12Crossing#
(NL-N
R)/
(NL+
NR)
(NB-N
T)/
(NB+
NT)
Measured @ SOUTH LR Measured @ NORTH LR
Measured @ SOUTH TB Measured @ NORTH TB
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