Positron Asymmetry and Polarization from the E166 September 2005 run
K. LaihemPrinceton meeting Princeton meeting 22-05-2006 Status Report Simulation studies E166...
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K. Laihem Princeton meeting Princeton meeting 22-05-2006 Status Report Simulation studies E166 experiment Karim Laihem
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Transcript of K. LaihemPrinceton meeting Princeton meeting 22-05-2006 Status Report Simulation studies E166...
K. Laihem Princeton meeting
Princeton meeting 22-05-2006
Status Report Simulation studies E166 experiment
Karim Laihem
K. Laihem Princeton meeting
•What we have achieved in E166 ? (e+ and photon asymmetry)
Convert the X axis from current to MeV
Co
nve
rt t
he
asym
met
ry t
o
po
lari
zati
on
K. Laihem Princeton meeting
Updated geometry E166_Geant4_Simulation
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18”
Entranceregion
Exitregion
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SpectrometerConversion target
Reconversion target
3.6”
7.78”
7.9”
9.4”
sole
noi
d
Entranceregion
Exitregion
K. Laihem Princeton meeting
-10 -8 -6 -4 -2 0 2 4 6 8 10
0
5
10
15
20
25
30 Data: Data22_BModel: GaussAmp Chi^2 = 0.20189R^2 = 0.99823 y0 0.00088 ±0xc 0.0 ±0.01116w 1.89446 ±0A 29.2 ±0
Axi
al F
ield
[G/A
]
Longitudinal Probe position Z [cm]
Solenoid Axial field.The fit function is a Gaussian profile
2
20
20)( w
zz
AeBzB
Where the coordinate z is given in centimeter.
984.1 ,0
2.29 ,00088.0
0
0
Wz
AB
Solenoid magnetic field. (SLAC’s measurements)
82
2
3
3 r
dz
Bd
dz
dBrBr
0B
2
22
4)(
dz
BdrZBBZ (1)
(2)
(3)
K. Laihem Princeton meeting
MERMAID field map implementation into E166_G4_SIM
X
Y
Z
(i,j,k)
(i+1,j,k)
(i,j+1,k)
(i+1,j+1,k)
(i,j,k+1) (i,j+1,k+1)
(i+1,j,k+1)
(i+1,j+1,k+1)
Z
X
Y
e+/e- Track
Figure 19. Scheme of one unitary segment for the 3D interpolation.
Figure 20. Scheme of the 3D segmentation using the unitary cube method for the field map implementation
K. Laihem Princeton meeting
IL = 0 A IL = 150 A IL = 350 A
Solenoid focusing effect.
e+ 2D Spatial distribution at the Entrance of the spectrometer.For different IL value (IL = 0, 150, 350 A) (Spectrometer OFF). Focusing effect of the lens is shown
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IS= 120IL = 200
IS= 160IL = 250
e+ spatial distribution showing the density(A), at the entrance of spectrometer(B) at the exit of spectrometer (C) and at the reconversion target for different setting points IS and IL.
IS= 160IL = 250
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E166_G4_SIM
Figure 33. Positron energy versus spectrometer current.
80 100 120 140 160 180 2002,5
3,0
3,5
4,0
4,5
5,0
5,5
6,0
6,5
7,0
7,5
8,0
8,5
9,0 G4 simulation ( = 0) MERMAID ( = 0) G4 simulation ( = 4) (140, 160 and 180 extrapol from 100) MERMAID ( = 4) G4 simulation ( = 4) (180 extrapol from linear fit)
Pos
itron
Ene
rgy
[MeV
]
Spectrometer current IS [A]
Ee+(180)=7.4 MeV
This point can not be seen by the simulation
If we use the First harmonic
(Ecutoff = 8.3 MeV)
? To be clarified
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(E166 Zeuthen group)
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E166_G4_SIM9 Xtals
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7%
-7%
N = 10 4
E e+ = 3.7 MeVP e+ = 70%
N = 10 4
E e+ = 3.7 MeVP e+ = 70%
300 bunchesCPU time ~24h
Asymmetry % = 0.43 ± 1.3
Prelim
inary
K. Laihem Princeton meeting
100%
-100%
N = 10 4
E e+ = 7 MeVP e+ = 100%
N = 10 4
E e+ = 7 MeVP e+ = 100%
150 bunchesCPU time ~17h
Asymmetry % = 13 ± 1.4
Prelim
inary
K. Laihem Princeton meeting
Positron Energy
[MeV]
Positron Polarization
[%]
Iron Polarization
[%]
Asymmetry
[%]
Analyzingpower
[%]
3.7 70 7 0.43 ± 1.3 8.77
7 99 99 13 ± 1.4 13
Electron Energy
[MeV]
Polarization
[%]
Iron
Polarization
[%]
Asymmetry
[%]
Analyzing
power
[%]
7 99 99 15 ± 1.0 15
Preliminary Preliminary TestWithout Annihilation (polarization=0)
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Summary
• Code optimization
• Computer power to see these small asymmetries with reasonable errors.
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