P1254503563oyBPu

1
Analyzer Magnetic Analysis
(Status Report)

• General Overview
• Spin and Magnetization
• Field Distribution Modeling
• Results from Flux and Field Measurements
• Electron Polarization of the Iron
• Remaining Work

E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler
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General Overview

M manetization n electron density µB
Bohr magneton g magneto-mechanical factor
electron polarization of the iron
Pe 0.07 ?Pe/Pe lt 0.05 (aim of
proposal)
error in e- polarization is dominated by
knowledge in effective magnetization M along the
photon trajectory

active volume Photon Analyzer
50 mm dia. x 150 mm long Positron Analyzer
50 mm dia. x 75 mm long
E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler
3
Spin and Magnetization
g magneto-mechanical factor obtained from
Einstein - de Haas type experiments,
related to gyromagnetic ratio ? (g/2)
(e/m)
Note g 2 ? Ms / M 1 (pure
spin magnetization) ? e/m
g 1 ? Ms / M 0 (pure orbit
magnetization) ? ½ (e/m)

and its ultimate implementation (Scott 1962)
g 1.919 0.002 for pure iron
i.e. orbital effects contribute about 4
the principle
E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler
4
Analyzer Magnets

? Analyzer
e Analyzer
Pickup Coils
CsI-Detector
e Analyzer
E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler
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Field Distribution Modeling(Vector Fields
OPERA-2d)
end
Bz (T)
20
15
10
R 0 mm
Z (mm)
center
longitudinal field distribution Bz (R,Z) field
drops gradually towards the ends Leff / L lt
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E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler
6
Field Distribution in 2d(Vector Fields OPERA-2d)
Z (mm)
R (mm)
longitudinal field distribution Bz (R,Z)
E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler
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Pickup Coils for Flux Measurements
used 4 turns of special coil wire with 40 wire
strands externally wired in series for 4 x 40
160 turns max.
Positron Analyzer Positron Analyzer Positron Analyzer Photon Analyzer Photon Analyzer Photon Analyzer
?z (mm) r (mm) n (turns) ?z (mm) r (mm) n (turns)
upstream -20 24.25 4 x 40 160 -57.5 24.25
center 0 24.25 4 x 38 152 0 24.25 4 x 40 160
downstream 20 24.25 4 x 40 160 57.5 24.25 4 x 40 160
dummy 0 0 0 0 0 0
() positron downstream became
dysfuntional after Oct. 2004 at SLAC ()
photon upstream was damaged already at DESY
E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler
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Flux Measurements
data taken by Zen - analyzed by Roman
measure voltage transients in pickup coils upon
current reversals
Positron Analyzer (-60 ? 60 amps)
Photon Analyzer (-60 ? 60 amps)
Sawtooth from Waveform Generator (for calibration
of time base)
E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler
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Flux Data
E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler
10
Flux and Field Measurements Results
Z 0 (center)
Note polarimetry was always done at full
saturation over the central region
(60A)
E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler
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Flux and Field Measurements
Z -20 mm
No significant field difference seen between
upstream and center
E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler
12
electron polarization of the iron
preliminary result for the e analyzer (6.94
0.17)
- and the nitty-gritty
E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler
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Remaining Work

• repeat magnetic modeling with correct
• central field values as measured
• choose finer mesh spacing
• same for photon magnet
• generate writeup

E166 Collaboration Meeting Princeton, 22-24 May
2006
Analyzer Magnetic Analysis K. Peter Schüler