Minutes of NAOJ-VIS meeting
Date: May 21st, 2014
Attendee: Flaminio, Aso, Barsuglia, Takahashi, Pena, Agatsuma, Ishizaki, Sekiguchi, Heijningen


Mass distribution problem of payload (Pena)
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* Comepnsation mass on IM
 - Missing weight for bottom GAS filter (13.8 kg) is added on the intermediate mass.
 - SUS blocks are used for compensation.
 - They are placed so that CoM of IM is at the same level as horizontal OSEMs.

* Magnetic field problem on actuators
 - In Virgo, PEEK is used instead of aluminum around actuators
 - In the current design, the actuation coils are ~5 cm apart from aluminum body surface.
   So, the magnetic field problem might be less significant.
 - Magnetic field on the aluminum surface should be compared with that in Virgo.
 - Hierarchical control should be investigated to know necessary force on actuators.


Report on OSEMs (Heijningen)
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* Fixing lens-LED distance
 - The beam propagation of LED light is investigated with changing lens-LED distance.
 - The beam never gets collimated, it gets always diverging.

* Calibration of OSEM sensor part
 - One OSEM shadow sensor is calibrated with fixed lens-LED distance.
 - The calibration curve is symmetric. A constant-sensitivity part can be found, whose range is ~0.5 mm.
 - The sensitivity to the orthogonal flag displacement is also investigated.
 - It is sensitive to the flag motion along beam axis, because of diverging beam propagation.
 - It is almost insensitive to the flag motion along the other orthogonal axis.


Procurement of Type-C (Takahashi)
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* Budget situation
 - Budget for VIS (40 MYen) is allocated to BF production, maraging wires, stacks and supports.
 - Other 7 MYen is allocated to R&D cost for TAMA prototype test.
 - Estimated budget is already over the plan. We need to cut R&D budget.

* Type-C suspension
 - VIS has no enough budget for type-C suspension production.
 - It would be necessary to bring 2 PO type suspension from TAMA BS chamber. (To Be Fixed)
 - 3D CAD model is anyway necessary. It will be drawn by Ishizaki-san.