coatings
SwissNeutronics prepares coatings for neutron optics using DC magnetron sputtering. The deposition process is highly developed to obtain layers with extremely smooth surfaces for providing highest neutron reflectivity. SwissNeutronics produces regular and polarizing supermirror with high m-values and excellent performance in terms of reflectivity and neutron spin polarization. Particular highlights are:
- Ni/Ti supermirror up to m = 7 with unrivaled excellent reflectivity,
- Fe/Si polarizing supermirror with high reflectivity up to m = 4.5, polarization approaching 100% and internal stress of virtually zero.
The following figures show representative reflectivity profiles of various supermirror prepared on floated glass and super-polished Borkron glass:
Ni / Ti supermirror - m ≤ 3.6
reflectivity profiles of Ni/Ti supermirror coatings for various m ≤ 3.6
Ni / Ti supermirror - m ≥ 4
reflectivity profiles of Ni/Ti supermirror coatings for 4 ≤ m ≤ 7
Fe / Si polarizing supermirror
spin dependent reflectivity and polarisation of a Fe/Si polarizing supermirror m = 4 (note the expanded scale for the polarization)
spin dependent transmission and polarization of a Si-wafer coated on both sides with Fe/Si polarizing supermirror m = 3.8 (note the expanded scale for the polarization)
FeCoV / TiN polarizing supermirror
spin dependent reflectivity and polarisation of a FeCoV/TiN polarizing supermirror m = 2.5 (note the expanded scale for the polarization)
non-magnetic supermirror
spin dependent reflectivity and polarisation of a non-magnetic supermirror m = 3.8; the deduced polarization confirms the non-depolarizing property (within errors of the measurement).
summary of performances
† polarization in reflection, determined at an applied field of H = 450 G
* no sufficient number of samples available for a reliable statistics
Ni/Ti
type | m-value | Rmin | Rave | Rmax | P† |
Ni/Ti | 1.2 | 0.97 | 0.98 | 0.99 | -- |
Ni/Ti | 1.5 | 0.94 | 0.96 | 0.98 | -- |
Ni/Ti | 2 | 0.92 | 0.93 | 0.95 | -- |
Ni/Ti | 2.5 | 0.88 | 0.89 | 0.91 | -- |
Ni/Ti | 3 | 0.86 | 0.88 | 0.90 | -- |
Ni/Ti | 3.5 | 0.79 | 0.81 | 0.83 | -- |
Ni/Ti | 4 | 0.76 | 0.78 | 0.81 | -- |
Ni/Ti | 5 | 0.66 | 0.69 | 0.72 | -- |
Ni/Ti | 6 | 0.58 | 0.61 | 0.65 | -- |
Ni/Ti | 7 | 0.46 | 0.49 | 0.52 | -- |
Fe/Si - FeCoV/TiN
type | m-value | Rmin | Rave | Rmax | P† |
Fe/Si | 2 | 0.90 | 0.92 | 0.94 | ≈ 0.99 |
Fe/Si | 2.5 | 0.87 | 0.89 | 0.91 | ≈ 0.99 |
Fe/Si | 3 | 0.84 | 0.86 | 0.88 | ≈ 0.99 |
Fe/Si | 3.6 | 0.78 | 0.80 | 0.82 | ≈ 0.99 |
Fe/Si | 4 | 0.76 | 0.78 | 0.80 | ≈ 0.99 |
Fe/Si | 4.5 | -- | 0.75 | -- | ≈ 0.99 |
FeCoV/TiN | 2 | 0.86 | 0.88 | 0.90 | ≈ 0.98 |
FeCoV/TiN | 2.5 | 0.76 | 0.78 | 0.81 | ≈ 0.98 |
FeCoV/TiN | 3* | -- | 0.70 | -- | ≈ 0.98 |
