1 KAGRA cryogenic payload kickoff meeting
   2 
   3 15th of Novermber 2013 (Fri) 10:00-13:00
   4 311, Second Research Complex, Kashiwa campus
   5 
   6 Attendees: Aso, Chen, Hirose, Ishizaki, Khalaidovski, Ohashi, Saito, Sakakibara, 
   7 Sekiguchi, Suzuki, Takahashi, Tokoku, Yamamoto
   8 SeeVogh: Akutsu, DeSalvo, Hayama, Kimura, Koike, Ono, Uchiyama
   9 
  10 1. "Reporters" are assigned.
  11 
  12 Since there are a lot of items, "Reporter" reports the progress status 
  13 of a bunch of items. And they check whether the progress in on time.
  14 If there are some problems, we must discuss issues in this meeting.
  15 
  16 The "Reporters" are as follows;
  17 
  18 1. Overall design - Schematic structure : Eiichi Hirose
  19 2. Sapphire monolithic suspension : Khalaidovski Alesandr
  20 3. Vertical spring (blade metal spring) : Hideharu Izhizaki
  21 4. Material : Toshikazu Suzuki
  22 5. Control : Dan Chen
  23 (6. Manufacture of 1st payload : Kazuhiro Yamamoto)
  24 (7. Manufacture of bottom filter : Ryutaro Takahashi)
  25 (8. Manufacture of sapphire mirror : Eiichi Hirose)
  26 
  27 An important message from Takanori (from the point of view of the simulation)
  28 If some parameters should be decided for experiments, let know him.
  29 He trys to fix those parameters at first.
  30 
  31 2. Sapphire monolithic suspension
  32 
  33 2-1.
  34 Motivation : Since the situation is not so clear, Eiichi and Sascha 
  35 presents the status. Kazuhiro's most important mission on the next week
  36 is to summarize the schedule and budget based on their presentation and so on.
  37 He must also show the priority.
  38 In short, the schedule about this topic 
  39 on the Microsoft Project should be revised.
  40 
  41 2-2. Eiichi's presentation
  42 Eiichi explained the three tests for 3D design.
  43 (a)Strength test at KEK
  44 (b)Thermal resistance measurement at ICRR   
  45 (c)Assembly test (if flatness of cut surface is lambda(630nm)/10 and 
  46 roughness is 20nm, it is OK for any cases).
  47 
  48 Discussion and comments about these tests;
  49 (i)Strength test is at 77K, probably. It is OK for us (although thermal expansion
  50 below 77K is quite small) ?
  51 (ii)In the strength test, a sample is cooled rapidly. Can thermal stress itself
  52 destroy the sample ? -> If we find so at the first experiment, we must consider.
  53 (iii)Homework from Saito-san (for lunch time or before we go to bed ?): 
  54 Simulation for residual stress near bonding during cooling. 
  55 Residual stress appears near surface of sapphire (3 micro meter) during cooling.
  56 Can indium compensate it ?
  57 (iv)In usual case, "strength test" implies "tensile strength test". Shear stress test 
  58 is not so easy. Although the shear strength can be derived from the tensile strength if 
  59 we discuss material, maybe, the story is different in the case of bonding.
  60 
  61 Schedule proposed by Eiichi. 
  62 
  63 Middle of February : Decision based on test (a) and (b)
  64 Test (c) must be after this decision. But, we are afraid that it takes long time.
  65 Mechanical dissipation measurement is not included in his schedule.
  66 End of March : Geometry of mirror cut (drilling) should be fixd.
  67 
  68 In any cases, Finite Element Analysis is necessary and improtant.
  69 
  70 Eiichi's idea : screw. In his idea, the suspension consists of 
  71 a mirror, ear, connector (it is some kinds of nail head, but, its volume 
  72 is much larger), rod.
  73 There is no srews between mirror and ear.
  74 The ear and a connector is combined by screws. The connector and 
  75 rod are also.
  76 Sapphire screw itself can be manifactured (Kazuhiro's comment;
  77 a female screw was made by Shinkosha.
  78 They said that manifacture of a male screw is easier).
  79 
  80 Some suggestions and discussion for sapphire screw
  81 (a)Bending length is about 5cm. We take it into account in any cases.
  82 (Some parts under ear ?)
  83 
  84 (b)It is better for the connetction between 
  85 rod and connector is not screw (thermal resistance)
  86 (Eiichi also mentioned so).
  87 (c)It is better for the screw between the ear and connector to have a head.
  88 
  89 (Items below this sentence are concerns and some of them are speculation)
  90 (d)Material of screw: Eiichi said that it is metal (Cu ?). 
  91 Is difference of thermal expansion a problem ?
  92 (e)"Optical contact" could grow between the ear and connector. They can 
  93 not be separated a few months later. 
  94 (f)Is contact surface enough (Only area under the screw head is contacted) ?
  95 (g)Is it tightened by hand ?
  96 (h)If a screw stacks, it is terrible.
  97 
  98 2-3.
  99 Sascha's presentation
 100 He emphasises that it takes long time to prepare (procurement) 
 101 and check bonding, fibers, blades and so on.
 102 
 103 Hydro Catalysis Bonding is excellent, but it is a nightmare when 
 104 fibers are broken.
 105 
 106 Alternative : (Weld or brazing) Indium. In the case which Sascha shows, 
 107 indium do not support a mirror.
 108 It is just a connection between an ear and a nail head of a fiber. But if it can support
 109 a mirror, it is excellent. 
 110 Anyway, it is worth to try the strength test proposed by Eiichi and 
 111 we should investigate how the strength depends on the thickness.
 112 
 113 Crucial point of indium : Control of thickness. 
 114 Since mechanical loss of indium is 
 115 large, thickness should be as small as possible. 
 116 A student who comes from Hannover (supported by ELiTES) will investigate 
 117 it in Japan.
 118 
 119 2-4.
 120 Forgotten item
 121 Sascha ordered sapphire samples for the thermal resistance test (they will be delivered 
 122 on the middle of December), but only for Hydro Catalysis Bonding. 
 123 We need other blocks for other bonding technique.
 124 Kazuhiro will summarize how many we must order after he consult Eiichi. 
 125 The direction of crystal axis and polish quality must be consider.
 126 
 127 3. Other discussion
 128 
 129 Saito-san and Ohashi-san said that a member of SEO must attend this meeting.
 130 We hope that the fast decision for the schedule or budget will be possible 
 131 (sometime, this member could decide in this meeting, maybe). 
 132 This member will be decided in the Excective Office meeting in the next Monday morning 
 133 and be announced in chief meeting in the next Monday afternoon.
 134 
 135 Most important message from Ohashi-san
 136 In any case, we must make efforts to win the budget 
 137 even if it is quite difficult. That is the motivation 
 138 to summarize the reseach plan, schedule, priority and so on. 
 139 
 140 Next meeting : 
 141 We will have the meeting 13:00 on every Tuesday (in principle, 
 142 this is face to face meeting although the teleconference 
 143 in SeeVogh will be reserved). 
 144 So, the next meeting is on 13:00 of the 19th of Nov.
 145 However, this meeting is only to report and check the progress.
 146 In the meeting on 26th of Nov., Kazuhiro shows the schedule for 
 147 sapphire monolithic suspension and Ishizaki-san explains 
 148 the schedule for the cryogenic vertical spring.  
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