Kazuhiro Yamamoto

1
Current status (ELiTES and Geometry of payload)
Kazuhiro Yamamoto Institute for Cosmic Ray
Research The university of Tokyo
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. 2012 -
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
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ELiTES
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 Physicsunirm1, 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 Physicsunirm1, ICRR-UT
  SEPT 2015
• Task 1.4 Actuators, sensors and mirror control
  at room and low temperature
• document month 48 Physicsunirm1, 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.

6
ELiTES
WP2 Cryogenic mirror (R. Nawrodt)
Mirror, Coating, Fibers to suspend mirror The
first meeting will be held
on 2nd or 4th of May.
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ELiTES
WP3 Cooling system (K. Somiya) Reduction
of cooling and warming time, Radiation
shield, Baffles, Mirror contamination
and so on
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ELiTES
Mailing lists for WP1,2,3 have already been made.
Since the announce e-mail was sent, please
subscribe to join them. If you did not receive
the annouce e-mail, let me know.
9
ELiTES
Ettore Majorana is here. If you have questions,
please ask him now.
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Geometry of payload
(a)Original idea
(b)Hot platform
300 K
Cold
Platform
300 K
Intermediate mass
Cold
Recoil mass for intermediate mass
Mirror
Recoil mass
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Geometry of payload
(b)Hot platform
Advantage Control and adjustment system
at room temperature
300 K
Cold
Initial cooling time is shorter ? Mirror
temperature is the same ? Y.Sakakibara
calculated.
12
Geometry of payload
(a)Original idea
300 K
Cold
13
Geometry of payload
(b)Hot platform
300 K
Cold
14
Geometry of payload
(b)Hot platform
300 K
Cold
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
300 K
Cold
17
Geometry of payload
(b)Hot platform
300 K
Cold
18
Geometry of payload
(b)Hot platform
External vibration T. Sekiguchis calculation
300 K
Cold
bKAGRA 310-21 m/rtHz at 80Hz 3.610-20 m/rtHz at
30Hz 1.510-19 m/rtHz at 10Hz
Vibration isolation should be better.
19
Geometry of payload
(b)Hot platform
Thermal noise Vertical spring must be cooled
(thermal noise).
300 K
Cold
20
Geometry of payload
(b)Cold platform
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.
300 K
Cold
21
Geometry of payload
Temperature change after start of laser operation
(b)Cold platform
300 K
20 heat links
22
Geometry of payload
(a)Original idea
(c)LIGO (like)
300 K
Cold
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).
IM
IMR
Recoil mass
Mirror
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Geometry of payload
(a)Original idea
Advantage of (b) Control and adjustment
system at room temperature Short initial cooling
300 K
Cold
Note Vertical spring at cryogenic temperature
and vibration isolation along heat link are
necessary (even in original idea (a)).
(b)Hot platform
300 K
Cold
25
Geometry of payload
(a)Original idea
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) ?
300 K
Cold
(b)Cold platform
300 K
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Geometry of payload
(a)Original idea
Advantage Smaller thermal noise
300 K
Cold
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).
(c)LIGO (like)
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