MAGIC II Mirrors and reflector M. Doro Udine. MAGIC Collaboration Meeting. 2006/05/10-13

Summary Prototypes and measurements Layout of the mirrors Layout of MAGIC II reflector REFLECTOR implementation Outlook

1m 2 first prototypes Different prototypes –Different internal glue –Different box shape –Different insulation 7 mirrors realized –2 with new 3M glue discarded –3 already installed on MAGIC I –2 in Munich for tests 1. Prototypes and measurements

1m 2 mirror layout Very similar to last MAGIC I small mirrors Central hole for the laser housing 1. Prototypes and measurements Mirror box + honeycomb Front plate

Layout comparison 50 cm mirrors 1 m mirror AMC motors Layout comparison 1. Prototypes and measurements

Mirror Heating New heating system for small mirrors tested: Small box with resistors set behind the mirror panel Lab test: W 1. Prototypes and measurements

Realization steps 1.Raw blank assembling Front plate glued with al box and honeycomb Already spherical shape 2. Diamond milling (LTech) a) Old system  Rotating machine b) New system  Lateral machine (?...) 3.Quartzum layer surfacing 4. Ready! 1. Prototypes and measurements

Old milling machines New machine  maybe founding problems  if money, 3 months for delivering 1. Prototypes and measurements

Test on the mirror spot Already performed on 3 mirrors Results: The rigidity of the new mirrors and the tune-up of the milling machine are now delivering very good results Spot is comparable to the one had for 0.5m mirrors! 0.5 cm 1. Prototypes and measurements

3 large mirrors already installed in Oct 05 but..winter has passed…

Adrian analysis Out of 3 new large mirrors installed 1 mirror shows very large reflected spot 2 mirror show scarse reflectivity  They are test mirrors!!  more aging investigation needed  absolute reflectivity tests required 1. Prototypes and measurements

Road to massive production Almost finalized decision on shape –98.5 cm x 98.5 cm –60mm thick hexcel structure –3mm Al plate –2mm back plate Realization steps already tested one by one After final tests massive production can start! 1. Prototypes and measurements

Tests Understand degradation of mirror mounted in MAGIC I Measure of reflectivity vs wavelength –Method to be investigated –Spectrometer? (with UAB) Aggressive test (in Munich) –load –temperature –humidity –Insulation To be performed in Munich next 2-3 weeks 1. Prototypes and measurements

[2] MAGIC II Mirror layout Situation up to now: –Already taken decision: innermost 6 rings of large mirrors (about 120 mirrors) 2 outer rings have larger contribution to aberration -Possible solution -Small mirror outside -Aspherical mirrors -Normal 1m mirrors

Simulations  simulation performed with REFLECTOR (thanks to Abelardo and Jordi Z.) All mirror 1m^2 All mirror 0.5 x 0.5m  consistency test with raytracing macro

Vertical incidence 2. Reflector layout Case perfect reflector: RMS worsen from 0.28cm to 0.56cm (100%) Real (actual) reflector: RMS worsen from 0.76cm to 0.91cm (19%) Inner pixel

Tilted incidence Worsening decrease with angle Reason is that coma aberration is determinant at high angles angleWorse 019% 0.510% 15% 1.53% 2. Reflector layout 0deg 0.5deg 1deg 1.5deg

Simulation with raytracing Basically same tests  confirms results

Conclusions 2. Reflector layout Conclusions –The effect of worsening is most remarkable for vertical incidence, but in any case the spot is almost within a small pixel. –The effect is more relevant at low energies –At large angles the coma aberration makes the two layouts almost equal. Only if delivering companies can ensure a better reflecting surface, a mixed layout with small mirror on the outside rings can be taken into account…

Advantages Smaller number of items (248 vs 960) Faster production Lighter structure Faster and easier installation on the telescope Self supporting (no panel needed) No manual interalignment necessary No need for taggering …nicer reflector 2. Reflector layout

REFLECTOR code Simulation with REFLECTOR: –Implementation of new reflector layout in REFLECTOR is ongoing –Occasion to clean software –Start estimation of MAGIC II sensitivity 2. Reflector layout

[3] Calendar (tentative) May ‘06  Tests and new test mirrors June ‘06  Tooling realization July ’06  Starting production first mirrors Spring ‘07  First batch installation End ’07  Reflector completed  Important to tests subsystems

Summary Tests are required, then production can start Question about aging of mirror installed to be understood Measurements of absolute reflectivity required Homogeneous 1m^2 reflector could be the best compromise END