1 Kazuhiro Yamamoto Institute for Cosmic Ray Research The university of Tokyo LCGT internal review (Cryogenic payload) 30 January 2012

2 I explain the cryogenic payload. This is a part of cryogenics, but it is also related with vibration isolation system.

3 1. Overview 1.1 Definition of cryogenic payload System to suspend the cooled mirrors It is surrounded by the inner radiation shields.

4 1. Overview 1.2 Important interface Cryogenic : Heat link and cryostat Vibration isolation : Type A (development, installation, commissioning) Facility : Clean room Mirror : How to suspend mirror, coating mechanical loss Auxiliary Optical Systems : Monitors and scattering light Main interferometer : Control Digital systems and Electronics : Control

5 1. Overview 1.3 Design phase Cryogenic payload is not necessary in iLCGT. However, the development should be in progress for bLCGT in the term of iLCGT. For final design for bLCGT, (1)1/4 prototype in Kashiwa 1/4 means number of cryocooler, not size. (2) Some R&D items are in progress.

6 2. iLCGT 2.1 Target specification (1)1/4 prototype in Kashiwa (a) How to assemble and install (b) Cooling test (c) Damping (including parametric instability) and Control

7 2. iLCGT 2.1 Target specification (2) Some R&D items (a)How to suspend mirrors using sapphire fibers (b)Vertical spring in cryostat (c)Development and test of sensors, actuators, motors in cryostat (d) Thermal noise (Q measurement of wires and coating and so on) (e) Seismic noise, external vibration noise (measurement of the vibration of shield) (f) Baffles for scattered light

8 2. iLCGT 2.2 Final design In principle, the design is in progress. (1) 1/4 prototype Similar system (except for sapphire mirror and fibers) (2)Sapphire fibers : 30 cm in length, 1.6 mm in diameter 4 fibers suspend 23 kg mirror. Clamps on the both sides (3)Vertical spring in cryostat About 1 Hz resonance, 300 kg load (4)Baffles for scattering light (discussion started)

9 2. iLCGT 2.3 Schedule -2013/3 : 1/4 prototype will come at Kashiwa. 2013/ /9 : Experiment of 1/4 prototype Other R&D items 2014/7-2015/3 : Procurement

10 2. iLCGT 2.4 Quality assuarance (a)1/4 prototype : almost all items (b) Sapphire fibers, material of mass and wires: Measurement of thermal conductivity, Q-values, and tensile strength (KEK) (c) Measurement of mechanical Q of coating (KEK) (d) Vertical spring in cryostat Design and measurement of resonant frequency and Q-values (NAOJ and ICRR) (e) Vibration measurement of radiation shield : ? (f) Baffles for scattered light : ?

11 2. iLCGT 2.5 Installation Sceanario -2013/3 : 1/4 prototype will come at Kashiwa 2013/ /5 : Vacuum test and cooling test without payload Assembling payload 2013/6 : Installation of payload, cooling test 2013/ /9 : Cooling test, Damping and control test -2014/9: All other R&D items are finished. Final design is fixed. 2014/7-2015/3 : Procurement

12 2. iLCGT 2.5 Installation Sceanario Human resources 1/4 prototype : 3 ? 6 items of R&D : 6 ? Cryogenic experiment apparatus KEK (small vacuum flask for liquid helium), ICRR (CLIK), ICRR (small cryocooler from Mio lab)

13 2. iLCGT 2.6 Risk management (1)Sapphire fibers Silicon ? (2)Vibration of shields (3) Vertical spring in cryostat

14 Current status : meeting, 101, sapphire fiber, Sekiguchi and Sakakibara M Bonding Euler spring, material selection,

15 3. bLCGT 3.1 Requirement (a) The temperature of the mirror should be below 20 K. (b) Control and damping of the position and angle of mirrors at cryogenic temperature. (c) The sensitivity is not limited by the thermal noise, external vibration noise, and control noise.

16 3. bLCGT 3.2 Preliminary design It is the same as that of iLCGT.

17 3. bLCGT 3.3 Schedule 2015/6-2016/8 Type A (including cryogenic payload) Installation and commissioning for end mirrors 2015/ /12 Type A (including cryogenic payload) Installation and commissioning for front mirrors

18 3. bLCGT 3.4 Prototype test 1/4 prototype

19 3. bLCGT 3.5 Quality assuarance 1/4 prototype

20 3. bLCGT 3.6 Installation scenario Red items are milestones which K. Yamamoto told to M. Ando. 2015/6-2016/8 X-End mirror 2015/6-2015/7 Type A installation 2015/7-2015/12 Cryogenic payload installation and test with fixed Type A 2016/1-2016/6 Type A+ Cryogenic payload test 2016/7-2016/9 Mirrors are replaced by sapphire ones.

21 3. bLCGT 3.6 Installation scenario Red items are milestones which K. Yamamoto told to M. Ando. 2015/6-2016/8 Y-end mirror 2015/7-2015/8 Type A installation 2015/8-2016/2 Type A test with dummy load 2016/2-2016/7 Cryogenic payload installation and test 2016/7-2016/9 Mirrors are replaced by sapphire ones.

22 3. bLCGT 3.6 Installation scenario Red items are milestones which K. Yamamoto told to M. Ando. 2015/ /12 Front mirrors 2015/ /5 Type A installation and adjustment 2016/9-2016/12 cryogenic payload installation and commissioning

Installation scenario Schedule table 3. bLCGT

24 3. bLCGT 3.6 Installation scenario Human resources 3 person for 1 cryostat ? 2015/7-2016/2 3 persons 2016/2-2016/12 6 persons

25 3. bLCGT 3.6 Risk management Human resources 3 person for 1 cryostat ? 2015/7-2016/2 3 persons 2016/2-2016/12 6 persons

26 IDC

27 Human resources

28 Sapphire fibers Namiki : They gave up to made and polish fibers with thick ends. There are unpolished straight fibers in KEK. If they are polished, we will check properties. The fibers has already been sent.

29 Bonding 常温接合：研磨を岡本光学に問合わせ中 （鈴木） メタライズ接合：京セラに依頼 (a 軸同士 ) サンプル送付済み