1 KAGRA vibration isolation meeting (8th of August 2012)
   2 
   3 
   4 Attendees: Sekiguchi, Takahashi, Ishizaki, Uchiyama, Yamamoto
   5 
   6 Ryutaro: Pre-isolator experiment. 2mm thickness shims are inserted.
   7 So, finally, the friction between the coil and the magnet disappears.
   8 Ryutaro and Takanori put load on the pre-isolator. Now, the load is 600 kg.
   9 The resonant frequency of the pre-isolator is slightly  higher than 0.2 Hz
  10 (In the
  11 case without load, the resonant frequency is about 1 Hz).
  12 If the 80kg load is added, the pre-isolator is at critical point. Takanori
  13 brought
  14 the lead blocks from the basement lab (they belong to Prof. Kuroda).
  15 Tomorrow, Takanori and Riccardo are going to put the lead blocks on the
  16 pre-isolator ([kagra-vi 00166]).
  17 
  18 Schedule of the pre-isolator:
  19 (1)The load is put and the resonant frequency is adjusted.
  20 (2)If the resonant frequency is lower than 80 mHz,
  21 the diagonalize of control system is started. Then, the robust control
  22 system is completed (Riccardo's comment after meeting: maybe one should start 
  23 even at this point, then refine the diagonalization as we go,
  24  will discuss with Takanori).
  25 (3)The meeting of the Physical Society of Japan (11th of September).
  26 (4)The load is put and the resonant frequency is adjusted. The goal is 30
  27 mHz.
  28 
  29 Takanori: Brittleness test of Maraging at low temperature
  30 Takanori, Yusuke Sakakibara, Kazuhiro tried this test this evening.
  31 The maraging was put into liquid nitrogen. Takanori hit it with hammer.
  32 It was NOT broken. Fine.
  33 
  34 Simulation with the local damping
  35 Takanori asked Masayuki Nakano (a freshperson of
  36 institute for cosmic ray research) to make the silumation with the local
  37 damping (Riccardo's comment after meeting: we should first add also 
  38 the damping using the shadowmeter using the suspension wire
  39 at the ceiling of the cryostat cavern, that will damp the first pendulum mode 
  40 of the chain, which is expected to be the first offender.).
  41 Takanori expect that the easiest way is the improvement of the Mathematica
  42 code
  43 developed by Takanori.
  44 Will Masayuki join the KAGRA vi mailing list ? We should ask his opinion.
  45 
  46 Kazuhiro Agatsuma joins this mailing list.
  47 
  48 Kazuhiro: Euler Buckling spring for cryogenic payload
  49 Hideharu visited the institute for cosmic ray research today.
  50 He, Ryutaro, and Kazuhiro discussed the Euler buckling spring.
  51 He confirmed that the requirement of the slenderness ratio, which depends on
  52 the dimensions of the spring. He will make new spring made from BeCu based on
  53 this requirement.
  54 Analysis of the experiment result looks strange. It is an issue
  55 which must be considered again.
  56 
  57 Although Euler spring is one of the candidates, the other ones for
  58 the cryogenic payload must be considered
  59 (Riccarco's comment after meeting:what is the use of Euler springs? 
  60 I first proposed them, we briefly discussed them,
  61 then I convinced myself (maybe not you all) that they are not useful for our
  62 purposes, that if we need a cryo spring for the intermediate mass we should stick
  63 with what we know, and we can do just as small and at lower frequency.  Incidentally
  64 the Euler spring is more prone to creep, it did not work until I provided David
  65 Blair with maraging.). Kazuhiro must consider the
  66 roadmap of the
  67 cryogenic payload.
  68 And the schedule of the candidates of the cryongenic spring must be told
  69 to him (Riccardo's comment after meeting: if we need to design GAS springs, 
  70 we can do in no time, we have the know how.).