1 Kazuhiro Yamamoto Institute for Cosmic Ray Research The university of Tokyo Current status (ELiTES and Geometry of payload) KAGRA(LCGT) cryogenic payload meeting 25 April 2012

2 ELiTES What is the ELiTES ? Grant for collaboration between KAGRA and ET European 7th Framework Programme Marie Curie action (Mar Feb. 2016) European people can visit Japan for KAGRA. For example, Luca Naticchioni will stay on this autumn (at least, one month).

3 ELiTES ELiTES consists of four Working Packages. WP1: Cryogenic payload (E. Majorana) WP2: Cryogenic mirror (R. Nawrodt) Fibers to suspend mirror (In KAGRA, it is included in Crygenic) WP3: Cooling system (K. Somiya) WP4: Organization

4 ELiTES WP1: Cryogenic payload (E. Majorana) Discussion has already started. The first meeting was held on 13th of April. Every month meeting General meeting : 2-3 Aug ? in Japan

5 WP1 structure Task 1.1: Seismic attenuation for underground interferometers  document; month 24; Nikhef, UniSannio, ICRR-UT MARCH 2014 Activities of this task already started are promising in view of the milestone. Task 1.2: Payload design, interface with seismic attenuator  document; month 48; Physics–unirm1, ICRR-UT MARCH 2016 Activities of this task started already but they have to be re-aligned. Task 1.3: Auxiliary attenuation systems for thermal links  document; month 36; Physics–unirm1, ICRR-UT SEPT 2015 Task 1.4: Actuators, sensors and mirror control at room and low temperature  document; month 48; Physics–unirm1, ICRR-UT MARCH 2016 Activities related to this task are progressing in Japan will be reported in May, in order to focus and coordinate KAGRA/ET common efforts. ELiTES

6 WP2: Cryogenic mirror (R. Nawrodt) Mirror, Coating, Fibers to suspend mirror The first meeting will be held on 2nd or 4th of May.

7 ELiTES WP3: Cooling system (K. Somiya) Reduction of cooling and warming time, Radiation shield, Baffles, Mirror contamination and so on

8 ELiTES Mailing lists for WP1,2,3 have already been made. Since the announce was sent, please subscribe to join them. If you did not receive the annouce , let me know.

9 ELiTES Ettore Majorana is here. If you have questions, please ask him now.

10 Geometry of payload (a)Original idea Cold 300 K Cold 300 K (b)Hot platform Platform MirrorRecoil mass Intermediate mass Recoil mass for intermediate mass

11 Geometry of payload Cold 300 K (b)Hot platform Advantage Control and adjustment system at room temperature Initial cooling time is shorter ? Mirror temperature is the same ? Y.Sakakibara calculated.

12 Geometry of payload (a)Original idea Cold 300 K

13 Geometry of payload (b)Hot platform Cold 300 K

14 Geometry of payload (b)Hot platform Cold 300 K

15 Geometry of payload (b)Hot platform Above 150 K (Until 15th day), heat transfer is dominated by radiation. In the best case, it takes 20 days (maybe).

16 Geometry of payload (b)Hot platform Cold 300 K

17 Geometry of payload (b)Hot platform Cold 300 K

18 Geometry of payload (b)Hot platform Cold 300 K External vibration T. Sekiguchi’s calculation Vibration isolation should be better. bKAGRA 3* m/rtHz at 80Hz 3.6* m/rtHz at 30Hz 1.5* m/rtHz at 10Hz

19 Geometry of payload Cold 300 K (b)Hot platform Thermal noise Vertical spring must be cooled (thermal noise).

20 Geometry of payload (b’)Cold platform Cold 300 K Although the platform is cooled, the heat links are connected to intermediate recoil mass, not platform. Heat links between intermediate mass and its recoil mass are not necessary (probably). In this case, this has smaller vibration via heat link than original idea (a) does.

21 Geometry of payload Cold 300 K (b’)Cold platform Temperature change after start of laser operation 20 heat links

22 Geometry of payload (a)Original idea Cold 300 K (c)LIGO (like)

23 Geometry of payload (c)LIGO (like) Advantage : Smaller thermal noise of recoil mass stage Disadvantage : The distance between IM and IMR could be changed when the actuators of the mirror work. This is the problem (for example, the efficiency of the actuators for IM could be changed). Recoil mass Mirror IM IMR

24 Geometry of payload (a)Original idea Cold 300 K (b)Hot platform Cold 300 K Advantage of (b) Control and adjustment system at room temperature Short initial cooling Note Vertical spring at cryogenic temperature and vibration isolation along heat link are necessary (even in original idea (a)).

25 Geometry of payload (a)Original idea Cold 300 K Cold 300 K (b’)Cold platform In the case without heat links between intermediate mass and its recoil mass Smaller vibration via heat link Mirror temperature is enough low if heat load is not so large. (b’) is better than (a) ?

26 Geometry of payload (a)Original idea Cold 300 K (c)LIGO (like) Advantage Smaller thermal noise Disadvantage : The distance between IM and IMR could be changed when the actuators of the mirror work. This is the problem (for example, the efficiency of the actuators for IM could be changed).

27 Geometry of payload There is no reason to adopt original idea (a). (b)Hot platform : Control and adjustment system at room temperature and short initial cooling (b’)Cold platform : Smaller vibration via heat link (c)LIGO (like) : Smaller thermal noise of recoil mass Details of actuators are necessary for discussion.

28 Geometry of payload Please give your opinion