Positron Asymmetry and Polarization from the E166 September 2005 run Gideon Alexander, Erez...
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Positron Asymmetry and Polarizationfrom the E166 September 2005 run
Gideon Alexander, Erez Reinherz-Aronis
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
General
• In the analysis we considered only the Central Crystal (Crystal #5)
• We adopted the approach that by chaining all runs together the local variations are averaged out.
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
Selection of Runs and Events
• 1st stage:SuperRuns.Runs with Spectrometer and Lens values
Runs were rejected whenEmpty runs.Beam off.15 Hz runs.
Spectrometer [A] 100 120 140 160 180
Lens [A] 220 260 340 360 374
Positron energy [MeV]
3.65 4.38 5.11 5.84 6.57
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
Selection of Runs and Events
• 2nd stage :
Pairs of events were accepted by‘Trigger' word*. ‘Latch' word*.
*These are a result of a careful study of the 'agup', 'x5_1[0]' and 'x5_1[1] variables.
Note: Events with ADC above 4000 were filtered out.
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
Use of the toroid 6130• The toroid currents was used to define the appropriate range
of the data. Taking ±2σ range from an overall Gaussian fit.
• The analysis was then carried out with and without a Toroid normalization.
Positron Asymmetry• Event Pair : Signal*, Background (Bg).• Gaussian Fit in general is poor we use it only to define the sample
rage.• For each spectrometer value we calculate L and R
601601
)(1
)(1
magnets
N
iii
eventsmagnets
N
iii
events
eventsevents
BgSignalN
RBgSignalN
L
*Signal = Signal over Background (Signal + Bg)
RL
RLAsyor
BgSignalBgSignal
BgSignalBgSignalAsy
6060
6060
)()(
)()(
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
Asymmetry Error
R
R
L
L
NRR
R
NLL
L
LRRLRL
LRAsy
RL
RLAsy
11
)()()(
2 222
• For a Gaussian distribution:
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
Asymmetry Error
R
R
L
L
N
ii
NR
s
NL
s
RL
LRAsy
xxN
s
11
)(
2
)(1
1
22
2
1
222
• Note: Gaussian Fit in general is poor
• Calculate Sigma by
• so the Asymmetry error can be written as
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
Gain 1, Low sensitivity (12 bit)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
3 3.25 3.5 3.75 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 6.75 7
Positron Energy [MeV]
As
ym
me
try
[%
]
1 sigma
1 sigma / tor6130
1.5 sigma
1.5 sigma / tor6130
3 sigma
3 sigma / tor6130
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
Gain 1, High sensitivity (15 bit)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
3 3.25 3.5 3.75 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 6.75 7
Positron Energy [MeV]
As
ym
me
try
[%
]
1 sigma
1 sigma / tor6130
1.5 sigma
1.5 sigma / tor6130
3 sigma
3 sigma / tor6130
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
Positron Asymmetry
ee
e APP
Positron Polarization
Ae+ (extract) from Table 13, E-166 Proposal, June 2003.
~0.073
Positron Asymmetry and Polarizationfrom the E166 September 2005 run
Prof. Gideon Alexander, Erez Reinherz-Aronis
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5 6 7 8 9 10
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5 6 7 8 9 10
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
CsI
Analyzing magnet (-60/+60)
W-Target
Lens
SpectrometerSpectrometerSpectrometerSpectrometer
e-
e-
e-
γ
γ
Undulator
Bend magnets
SLC
e-
e-
Analyzing magnet (-60/+60)
γ detectors
E-166 @ FFTB (SLAC)
Backup 3
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
Backup - values for Polarization
Spectrometer [A] Ee+ Ae+
100 3.65 0.1931
120 4.38 0.1867
140 5.11 0.1688
160 5.84 0.1600
180 6.57 0.1585
Backup 4
Ae+ (extract) from Table 13, E-166 Proposal, June 2003 (Averages).
E-166 - Princeton, May 2006
Gideon AlexanderErez Reinherz-Aronis
Backup – Toriod cutsSpectrometer [A] Low
limitHigh
limit
100 490 550
120 500 520
120 520 570
140 480 538
140 538 600
160 530 567
180 525 565
electrons 500 520
electrons 520 550
electrons 560 590
Backup 5