PHENIX local polarimeter @ RUN9 2009/03/30 @ RHIC meeting Manabu Togawa for the PHENIX 1.
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Transcript of PHENIX local polarimeter @ RUN9 2009/03/30 @ RHIC meeting Manabu Togawa for the PHENIX 1.
PHENIX local polarimeter @ RUN9
2009/03/30 @ RHIC meeting
Manabu Togawa for the PHENIX
1
Leading neutron asymmetry from polarized pp collision
• Discovered at ZDC kinematics, ±2.8 mrad, in RHIC RUN2. – -10% level in forward kinematics
– Consistent with zero in backward
2
RL
RLN
dd
ddA
Interaction
LR definition
RUN 2
Asymmetry for neutron ID sample
Phys. Lett. B650 : 325-330 (2007)
150
unit:mm
100
Hadronshower
5
PHENIX Setup
3
ZDC(Zero Degree Calorimeter)
10*10cm ±2.8 mrad
3 modules150X0 5.1λI
SMD
1 ZDC
SMD(Shower Max Detector)
Neutron position can be decided by centroid method.
Dx magnet
Slat :7 for x-position8 for y-position
Data set for PHENIX local pol.• DAQ mode (offline)
Good neutron ID (taking with BBC trigger)
Can see phi-dependent
trigger is DAQ band limit (8-10 kHz as maximum)
need time to analysis
• Scaler mode
Many statistics without DAQ band width
Get result rapidly
can be high BG
need to start PHENIX DAQ so far (for clock sync.)
4
Detector(ZDC,SMD)
FEM DAQ
LL1 scaler(FPGA)
Start (clock sync.)
ADC, TDCCharge
SMD : hit map according to TDC hit
Until RUN8, we have done LP with DAQ mode.From RUN9, scaler mode is implimented.
Accumulating data in each 5 mins. (to DB)
* SMD is standby mode except for collision due to the high BG before collimation
DAQ modePhi-dependent asymmetry @ RUN9
5
From first transverse collision at PHENIX, Fill#10228 (2/25)
BBCLL1&(ZDCN|S) ~20 M evtsBy square root formula
Blue forward
Blue backward
Yellow forward
Yellow backward
Local pol. scaler
• Threshold for making pattern– 20 MIP equivalent
– High threshold is expected to select neutron
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 board4 patterns ×2 (N or S) ×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
6
Scaler counts(Fill#10454)
- 5 mins data (2009/03/29 15:50-55)- Small BG can be confirmed by unfilled bunch
7
Blue : unfilled + yellow : filled
Blue : filled + yellow : unfilled
Background not related to collision is very low, 10-3 level for beam gas.
Fill#10371 (transverse pol.)
5 mins data
RED : yell pol. ↑ BLUE : yell pol. ↓ RED : blue pol. ↑ BLUE : blue pol. ↓)()(
)()(
TRBL
TRBL
NN
NNA
Systematic study by unpol. beam
• Unpolarized beam was delivered as Fill#10372– Cross check for all polarimeters.
– Asymmetries in DAQ mode (phi-dependent asymmetry) and scaler mode were consistent with zero.
9
DAQ mode : Fill#10372 (unpol.)
10
Blue forward
Blue backward
Yellow forward
Yellow backward
Scaler mode : Fill#10372 (unpol.)RED : yell pol. ↑ BLUE : yell pol. ↓ RED : blue pol. ↑ BLUE : blue pol. ↓
Time dependent @ transverse data• From data, polarization is same
bunch-by-bunch
• Fit by following parameters with spin pattern– Blue asymmetry
– Yellow asymmetry
– Detector asymmetry
• In this case,– Blue backward asymmetry
– Yellow forward asymmetry
– Detector asym. in SOUTH ZDC12
Cross#
Measured @ SOUTH
RED : yell pol. ↑ BLUE : yell pol. ↓
Fill#10288
• Extract from SOUTH measurement– Yellow forward asym.
– Blue backward asym.
– Detector asymmetry in SOUTH
• 2/25 3:00-7:00
13
Fill#10325• Extract from SOUTH
measurement– Yellow forward asym.
– Blue backward asym.
– Detector asymmetry in SOUTH
• 3/10 0:00-11:00
• We have small asymmetry in first 3-4 hours.– High BG from collision related?
– Collision angle has been changing?
– Situation was changed fill by fill.
– For asymmetry value, we took flat region. 14
pC vs PHENIX Loc. Pol.Polarization (%), not normalized (!) vs fill
Raw asymmetry (%)
Online Polarization (%), not normalized (!) vs fill
Ratio
2/NDF=21/102/NDF=14/9
Fill-by-fill systematics
From Sasha’s slide
To longitudinal run
• First beam with rotator on was delivered as fill#10382.
16
phi asymmetry (Fill#10382)
Value@transversefor BLUE: 0.072±0.004
BLUE forward
BLUE backward
Yellow forward
Yellow backward
Value@transversefor YELLOW : 0.079±0.005
17
Scaler (Fill#10382)
18
RED : yell pol. ↑ BLUE : yell pol. ↓ RED : blue pol. ↑ BLUE : blue pol. ↓
First rotator ON : Fill#10382
Raw asym./CNI pol. BLUE YELLOW
@ Transverse 0.072±0.004 0.079±0.005
@ Rotator ON 0.011±0.002 0.005±0.002
Transverse component 15±3 % 6±3 %
From phi fit (only amplitude)
From the scaler
Raw asym./CNI pol. BLUE YELLOW
@ Transverse 0.0338 0.0379
@ Rotator ON : LR 0.0015 0.0004
@ Rotator ON : UD 0.0039 (11.5%) -0.0020
Transverse component 12.4 % 5.4 %
19
Offline and scaler asymmetries are consistent Switch to physics data taking at PHENIX
Rotator tune at Fill#10399
• Rotator feed back during fill : Successfully
20
Rotator current was changed
Summary• PHENIX LP work is successful.
– Scaler mode works well, consistent with offline analysis.
• Asymmetry is not correct, typically smaller, in the begging of fill due to
– High backgroud collision related?
– Beam orbit or collision angles are changed? (also appears in detector asymmetry)
– First longitudinal data looks transverse component is remained at BLUE beam (radial direction)
• Feed back is successful during fill.
• Now it is back to original one due to blue pol. life time.
21
Decrease during blue pol.?Fill#10439
22Increase BG after CNI measurement
Detector asymmetryhas been changed during fill
23Increase BG after CNI measurement
backup
24
Event structure study using pythia input.@ 200 GeV
pid pid
1 Gamma 10 K0 long
2 Positron 11 K+
3 Electron 12 K-
5 Mu+ 13 Neutron
6 Mu- 14 Proton
8 Pi+ 15 Antiproton
9 Pi- 25 Antineutron
Black : sumGreen : gammaBlue : neutronRed : proton
n
p
ZDC threshold is ~5GeV
25
Detector asymmetry
26
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. 27
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
28Crossing#
(NL-N
R)/
(NL+
NR)
(NB-N
T)/
(NB+
NT)
Measured @ SOUTH LR Measured @ NORTH LR
Measured @ SOUTH TB Measured @ NORTH TB