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MAGIC Collaboration Meeting Sofia May, 27-31 (2007) MAGIC II Mirrors Features Production Calendar M.Doro for the Padova group Summary 1) 2) 3) 4) 5) 6) MAGIC I mirrors replacement MAGIC II reflector Padova mirrors INAF-Medialario mirrors Production status and fundings Calendar of installation 1) MAGIC I mirrors replacement Status checked October 06 (Dazzi) April 07 (Garcz) Merged analysis to decide substitutions: table of substitution produced Possibility to put 2 glass mirrors to check performances In LP already 47 mirrors since Sept06 Damaged mirrors 22 very bad 3 empty places 16 pretty bad (>1 bubble) 8 still to be decided (47 in total) With this installation all the BAD mirrors are replaced 1) MAGIC I for 2008 • Installation: July, 2-3week • 2 technicians + Francesco (PD) • Markus Garczarczyk • 2 more people needed for 2nd crews • Additional ~50 mirrors show already small bubbles probable replacement 2008 • Also possibility to make future replacements with 1m^2 mirrors instead of small mirrors 2) MAGIC II reflector scenarios The reflector of MAGIC II will be entirely of 1m^2 mirrors of two types: PADOVA design (aluminum mirrors) INAF-Medialario design (glass mirrors) Two possible installation scenarios (PADOVA - INAF): 88 120 128 160 Radii of curvatures Inner rings (Padova) QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture. Outer rings (Medialario) Radius of each mirrors depends on the position It is a compromise, chosen solution: average radius Histograms produced for production of Padova and Medialario mirrors 3) Design of Padova mirrors 1. 2. 3. 4. Aluminum “skin” 985x985mm Aluminum box Honeycomb 60mm with microholes Structural glue inside to keep all together (curing in autoclav) 5. Epoxy glue on the outside perimeter for insulation 6. Sink at the center for housing the AMC laser 7. Back holes for mounting the actuators Improvements MAGIC I mirrors were 0.5x0.5m^2 Good quality but problem with interalignment of 4 mirrors in a panel MAGIC II All reflector bu 1m^2 mirrors Design similar but enhanced performances The increase width of the honeycomb inside the mirrors increased the rigidity of the structure: increased results of milling: very good PSF increased reproducibility of radius of curvature reduced astigmatism Spot PSF LED Performed on 4 mirrors at LT Technique: the mirrors is illuminated by a pixel twice the focal length far. A CCD camera analyze the image on the focal plane. WE NEVER PRODUCE SO NICE MIRRORS! They image the LED at 34 m mirror # r_90 (mm) 11 12 13 14 2,86 3,90 2,34 3,12 PSF 5,72 7,80 4,68 6,24 SPOT is d90=5mm 1/6 of the pixels diameter Insulation Performed on 2 mirrors in MPI Technique: immersion in hot water that heat the mirrors so that air is pressured outward Results: a lot of bubbles came out, due to bad sealing Action: changed sealing technique Reflectivity Measures: 4 mirrors measured at LT by Padova 2 mirrors measured at MPI (preprod) Padova (Enrico Giro): Spectrophotometer Ocean Optics HR2000 + integrating sphere Range 450-750 nm Average reflectivity is for (87,87,89,87)% for mirror 1,2,3,4 Total refl. is 95% MPI (Ralf Kosyra) Range 350-750 nm Reflectivity between 80-90% Diffuse light <1-10% depending on lambda Radii of curvature mirror # p (m) q (m) 11 12 13 14 33,99 34,07 34,00 34,04 34,26 34,33 34,26 34,30 average 34,13 34,20 34,13 34,17 4 mirrors measured Radii in good agreement within prescription We could mount the mirrors in a ordered way from the center outward Low astigmatism Other 20 mirrors will be measured in June and better statistics Conclusions on new Padova mirrors Quality of the reflected spot is very good Astigmatism reduced Increased rigidity enhanced performances The design is ultimated and tests almost confirm the quality More statistics on 20+ mirrors begin of June The best mirror we ever built 4) INAF mirror (Medialario company) INAF = Italian National Astro-Physics Institute Medialario = Optics company (Intel), Milan (I) INAF received fundings for covering 1/3 of MAGIC II reflective surface (>200k) New design for their mirrors: Glass mirrors Cold slumping technique COLD SLUMPING Technique • A thin glass sheet (1-2 mm) is elastically deformed so to retain the shape imparted by a mould having convex profile. If the radius of curvature is large, the sheet can be pressed against the mould using the vacuum suction. • On the deformed glass sheet (under vacuum force) is glued an honeycomb structure that provide the structural rigidity. • Then a second glass sheet is glued on the top to create a sandwich. • After releasing the vacuum, on the concave side is deposited a reflecting design for their mirrors coating (Aluminum) and a thin protective coating (Quartz) Features Mirrors with spherical or parabolic profile are possible (once a master with adapt profile is available) Weight of the panels extremely contained, 9.5 kg/m2 Low production costs (about 1.5 K€/m2) Massive production with short manufacturing times. For ex. 5 mirrors per day if 5 masters are available. But… the quality is worse than the Padova ones Many characterization/commisionings are still missing (ageing, mechanical resistance, laser positioning, mounting on the telescope…) First prototypes • A diamond turned mould has been realized by the LT-ULTRA (German company) • A number (4) of cold slumped mirrors has been realized and characterized in collaboration with MedialarioTech. • 1 panel at ETH (Zurich) for test on mechanical implementation • 1 panel at MPI for water immersion and optical testing • 2 panels now in La Palma to be installed in Magic II (or MAGIC I?) • All these activities has been carried out in tight collaboration with INFN-Padua Optical characteristics 80% of the light within d=10mm 90% of the light within d=15mm Inner pixel Spot is saturated to see the image tails (few bits camera) INAF Calendar Until july 2007: finish tests and ideation Mechanical tests Thermic stresses Measures of radii of curvature Insulation Decision on laser housing Decision on installation September 2007 - star massive production February 2008 - delivering of the entire batch Spring 2008 - installation 2) Status of the production Raw blanks 80 raw blanks ready, all 128 by end June. 69 ready to be milled (+laser sink and +screw holes) LT rate is low (0.5-1 mirror/ working day) (learning curve?) >15 already milled 4+2 measured (4=Padova, 2=MPI) Begin June second measurement (Padova) + expedition to Bremen for coating 60-80 ready for end September Quartz coating 2 already done 60-80 ready by October Shipping with container(?) from Munich in October 3) Funding Mirror cost: Raw blank = 950 Milling+quartz = 1850 total = 2800 /mirror Already paid (270k) 128 raw blanks (thanks to BCN(24k), Udine (8k)) 80 millings Additional funds for future 40 k (Tuorla) 20 k (UAB) Ask for 120 k (INFN) 80+ mirrors funded by INAF We have already all the money for 128 Padova mirrors plus money for 88-100 INAF mirrors Installation scenarios BASIC: end October/begin November we install all the mirrors we have for that moment: 50-80 from Padova (internal rings) 20+ from INAF (external rings) 128/160 ready in spring 2008 remaining INAF mirrors delivered in February 2008 All surface installed for spring 2008. Still missing agreement on installation procedure: Horizontal telescope Cherry picker … END