MAGIC II Mirrors Features Production Calendar M.Doro for the Padova group MAGIC Collaboration Meeting Sofia May, (2007)

Summary 1)MAGIC I mirrors replacement 2)MAGIC II reflector 3)Padova mirrors 4)INAF-Medialario mirrors 5)Production status and fundings 6)Calendar of installation 1)MAGIC I mirrors replacement 2)MAGIC II reflector 3)Padova mirrors 4)INAF-Medialario mirrors 5)Production status and fundings 6)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  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 Additional ~50 mirrors show already small bubbles  probable replacement 2008 Also possibility to make future replacements with 1m^2 mirrors instead of small mirrors Additional ~50 mirrors show already small bubbles  probable replacement 2008 Also possibility to make future replacements with 1m^2 mirrors instead of small mirrors Installation: July, 2-3week 2 technicians + Francesco (PD) Markus Garczarczyk 2 more people needed for 2nd crews Installation: July, 2-3week 2 technicians + Francesco (PD) Markus Garczarczyk 2 more people needed for 2nd crews

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):  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):

Radii of curvatures  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  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 Inner rings (Padova) Outer rings (Medialario)

3) Design of Padova mirrors 1.Aluminum “skin” 985x985mm 2.Aluminum box 3.Honeycomb 60mm with microholes 4.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 1.Aluminum “skin” 985x985mm 2.Aluminum box 3.Honeycomb 60mm with microholes 4.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 inter- alignment 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  MAGIC I mirrors were 0.5x0.5m^2  Good quality but problem with inter- alignment 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  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  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 SPOT is d90=5mm 1/6 of the pixels diameter LED

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  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 HR integrating sphere  Range nm  Average reflectivity is for (87,87,89,87)% for mirror 1,2,3,4  Total refl. is 95%  MPI (Ralf Kosyra)  Range nm  Reflectivity between 80-90%  Diffuse light <1-10% depending on lambda  Measures:  4 mirrors measured at LT by Padova  2 mirrors measured at MPI (preprod)  Padova (Enrico Giro):  Spectrophotometer Ocean Optics HR integrating sphere  Range nm  Average reflectivity is for (87,87,89,87)% for mirror 1,2,3,4  Total refl. is 95%  MPI (Ralf Kosyra)  Range nm  Reflectivity between 80-90%  Diffuse light <1-10% depending on lambda

Radii of curvature  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  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  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  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) 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…)  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 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  80% of the light within d=10mm  90% of the light within d=15mm Spot is saturated to see the image tails (few bits camera) Inner pixel

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 star massive production  February delivering of the entire batch  Spring installation  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 star massive production  February delivering of the entire batch  Spring 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  ready for end September  Quartz coating  2 already done  ready by October  Shipping with container(?) from Munich in October  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  ready for end September  Quartz coating  2 already done  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 INAF mirrors  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 INAF mirrors

Installation scenarios  BASIC: end October/begin November we install all the mirrors we have for that moment:  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  Still missing agreement on installation procedure:  Horizontal telescope  Cherry picker  …  BASIC: end October/begin November we install all the mirrors we have for that moment:  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  Still missing agreement on installation procedure:  Horizontal telescope  Cherry picker  … END