UV-reflective dielectric foil development - MAGIC
UV-reflective dielectric foil development - MAGIC
UV-reflective dielectric foil development - MAGIC
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<strong>UV</strong>-<strong>reflective</strong> <strong>dielectric</strong> <strong>foil</strong><br />
<strong>development</strong><br />
M. Shayduk, E. Lorenz, R. Mirzoyan<br />
CTA meeting, November 3-5 2008, Padova, Italy<br />
CTA meeting, November 3-5, 3 5, 2008, Padova
Interference filter principle:<br />
Alternating high/low refractive<br />
Index materials with λ/4 thicknesses<br />
For Winston Cones:<br />
“Sandwich”<br />
Multilayer <strong>dielectric</strong> <strong>foil</strong><br />
of 3M <strong>foil</strong> and <strong>UV</strong>-<strong>reflective</strong> stack<br />
~8% gain compared to Al on mylar<br />
(folded with Cher. spectrum<br />
for Zenith= 0 )<br />
CTA meeting, November 3-5, 3 5, 2008, Padova<br />
SiO2 Nb2O5 -> HfO<br />
3M <strong>dielectric</strong> Foil<br />
3M <strong>foil</strong> reflectivity<br />
Commercially available!
Multilayer <strong>dielectric</strong> <strong>foil</strong><br />
Reflectivity curve changes with incident angle:<br />
CTA meeting, November 3-5, 3 5, 2008, Padova<br />
Angle 0 0 90 0
Multilayer <strong>dielectric</strong> <strong>foil</strong><br />
Cherenkov photon hitting angle<br />
distribution (Winston Cone<br />
surface) peaks at ~65 deg<br />
-> To minimize number of layers<br />
(cost) Multilayer stack design<br />
should be optimized for that.<br />
CTA meeting, November 3-5, 3 5, 2008, Padova
20 layers of SiO2/HfO2 directly on<br />
3M PET <strong>foil</strong> for 45deg incidence<br />
( scattered light not included in<br />
total reflectivity)<br />
First HfO2 sample !<br />
(Fraunhofer Institute fuer Plazma<br />
physik, Dresden)<br />
Next samples with full 30-40 layers<br />
stack:<br />
Nov.-Dec. 2008<br />
Multilayer <strong>dielectric</strong> <strong>foil</strong>c<br />
CTA meeting, November 3-5, 3 5, 2008, Padova<br />
Bare 3M <strong>foil</strong> reflectivity<br />
Commercially available!<br />
Improvement in<br />
<strong>UV</strong>-region<br />
(45 deg incidence)
20 layers of SiO2/HfO2 directly on<br />
3M PET <strong>foil</strong> for 0deg incidence<br />
( scattered light included in total<br />
reflectivity)<br />
First sample !<br />
(Fraunhofer Institute fuer Plazma<br />
physik, Dresden)<br />
Next samples with full 30-40 layers<br />
stack:<br />
Nov.-Dec. 2008 !<br />
Multilayer <strong>dielectric</strong> <strong>foil</strong>c<br />
CTA meeting, November 3-5, 3 5, 2008, Padova<br />
20 layers on mylar<br />
(0 deg incidence)<br />
Improvement in<br />
(0 <strong>UV</strong>-region deg incidence)<br />
(45 deg incidence)<br />
20 layers on 3M PET <strong>foil</strong>
Dielectric Mirrors:<br />
CTA meeting, November 3-5, 3 5, 2008, Padova<br />
~8% gain compared to Al on mylar<br />
E. Lorenz talk, this meeting
Summary<br />
Winston Cones:<br />
CTA meeting, November 3-5, 3 5, 2008, Padova<br />
• Direct coating of 3M <strong>foil</strong> tested (no need for gluing two <strong>foil</strong>s)<br />
• 20 layer SiO2/HfO2 stack showed promising results<br />
• Production of full 30-40 stack will start in Fraunhofer Instutute<br />
fuer Plasma Physik after delivery of Hafnium target in<br />
November (10 m 2 )<br />
• ~8-10% gain in light collection (folded with Cher. Spectrum)<br />
Mirrors:<br />
• Coating of ~0.5-0.8 m wide panels is possible<br />
• ~8-10% gain in light collection
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