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