1. Neutron Polarization On The 10-4 Level
C. Klauser1, 2 , T. Bigault1, P. Böni 3, 4, J. Chastagnier1, P. Guimera-Millan1, D. Jullien1, N. Rebrova 5, M. Schneider 4 and T. Soldner1
1 Institut Laue-Langevin, Grenoble, France
2 Atominstitut TU Wien, Austria
3 E21, TU Munich, Germany
4 Swissneutronics, Switzerland
5 University of Heidelberg, Germany 1

2. Neutron Polarization Supermirrors Helium Spin Filter
Goal: Control polarization of large, cold neutron beam with 10-4 accuracy
Supermirrors
Large wavelength acceptance
Time-constant performance
Changes beam divergence and distribution
Best performance: 99.7 % polarization (crossed XSM geometry)
Helium Spin Filter
High polarization
Conserves beam divergence
Analytical description
Wavelength dependence
Time dependence
Low transmission at high performance

3. The Opaque Test Bench: High Precision Analysis
Polarizing/Analyzing Power
99.99 % reached
AP Product
Wavelength [Å]
First test November 2010 at ILL, PF1B

4. Spin Flipper
RF-Flipper

5. Depolarization in Polarizing Supermirrors
Parameters tested:
Magnetizing Field
Material: Co-Ti, Fe-Si
Supermirror factor m
Scattering angle/wavelength
Production : ILL, SwissNeutronics, Uni Mainz

6. Results Depolarization at low field up to 10-2
UP-DOWN FLIP
DOWN-UP FLIP
350 Gauss
8000 Gauss
Depolarization at low field up to 10-2
Depolarization due to misaligned domains
Magnetization varies with layer thickness
Similar depolarization in transmission and reflection
High magnetizing field (~0.8 T)
m-value: as low as possible
CoTi better at low field, FeSi better at high field
SuperAdam (A. Devishvili)

7. The Crossed Supermirror X-SM GeometryB
M. Kreuz et al., Nucl. Instr. and Meth. A 547 (2005) 583.
Helium cell
Mirror
Mirror
99.97 (1) %
λ= 5.3 Å

8. Conclusions Opaque Helium cells: High Analyzing Power > 99.99%
Diagnostic tool Opaque Test Bench
Supermirrors
Depolarization of all samples strongly influenced by magnetizing field
Present in reflection and transmission, influence by wavelength/angle
Increased X-SM performance by one order of magnitude to (3) %
Flipper
Flipping efficiency > % measured
All essential components for polarized neutron decay experiments were experimentally proven to perform in a satisfactory way on the 10-4 level
1491- SO 1058/1-1
MERCI:
Didier Berruyer, Thierry Bigault, Peter Böni, Jérémie Chastagnier, Pierre Courtois, Anton Devishvili, Pilar Guimerá Millán , David Jullien, Thorsten Lauer, Pascal Mouveau, Sasha Petoukhov, Natalyia Rebrova, Antonello Rizzo, Christian Schanzer, Torsten Soldner