11

Kazuhiro Yamamoto

Institute for Cosmic Ray ResearchThe university of Tokyo

Current status(Experiments in Toshiba,

Susupension model, Sapphire fibers, Misc.)

KAGRA cryogenic payload meeting26 September 2012

Experiments in Toshiba

2

Experimental plans in Toshiba

In this autumn, there will be cooling test of shileds in Toshiba Keihin Product Operations.

At the same time, we have experimental plans in Toshiba.

(1) Heat load test(2) Measurement of vibration of shield(3) Measurment of initial cooling time

3

Vibration of shield could be problems. Vibration via heat links, Scattered lightThis measurement is at cryogenic temperature and in vacuum.

Luca Naticchioni (Rome) and Dan Chen will measure vertical and horizontal vibration of radiation shield of KAGRA in cooling test, respectively.

D. Chen’s talk

Experimental plans in Toshiba (2) Measurement of vibration of shield

Experiments in Toshiba

4

Luca Naticchioni’s accelerometer

Experimental plans in Toshiba (2) Measurement of vibration of shield

Experiments in Toshiba

5

At beginning of initial cooling, heat transfer is dominated by radiation.

Initial cooling time for cryogenic payload is about 2 months (if no tricks).

Diamond Like Carbon (DLC) coating (High emissivity, Large radiation) on shields and payload (except for mirror)

Y. Sakakibara’s talk

Experimental plans in Toshiba (3) Measurment of initial cooling time

Experiments in Toshiba

6

Initial cooling time with DLC (shield and mass)

Y. Sakakibara’s talk

Almost half !

Experimental plans in Toshiba (3) Measurment of initial cooling time

Experiments in Toshiba

7

We must check the effect of radiation (and DLC coating) on the initial cooling time experimentally.

We suspend something without heat link inside shield and monitor the temperature of something in shiled during cooling test.

What is something ?Sample 1 : Sapphire and metal hollow sphere Sample 2 : Dummy payload (hollow masses)

Experimental plans in Toshiba (3) Measurment of initial cooling time

Experiments in Toshiba

8

Sample 1 : Sapphire and metal hollow sphere

Experimental plans in Toshiba (3) Measurment of initial cooling time

Evaluation of emissivity

Scaling law (Y. Sakakibara’s small experiment: 30 mm in diameter)His talk

(100 mm in diameter)

(100 mm in diameter)

Experiments in Toshiba

9

Sample 2 : Dummy payload (hollow masses)

Experimental plans in Toshiba (3) Measurment of initial cooling time

Half sizeHollow masses (~5 kg)DLC coatingSapphire bulk as dummy mirror

Preparation is in progress.S. Koike : Drawing

Experiments in Toshiba

1010

Schedule of cooling test and other experiments Schedule could be changed !October : 1st cryostat Sapphire and metal hollow sphere without DLC coatingNovemeber : 2nd cryostat Measurement of vibration of shield (Luca)December : 3rd cryostat : Sapphire and metal hollow sphere with DLC coatingJanuary : 4th cryostat Dummy payload Measurement of vibration of shield (Dan Chen)

Experiments in Toshiba

11

Small meeting on 28th of Aug.Attendees : Y. Aso, T. Sekiguchi, M. Nakano, and K. Yamamoto

T. Sekiguchi has already constructed the code to evaluate external vibraion and thermal noise. M. Nakano proceeds with the improvement to consider control scheme.

Suspension model

1212

IMPEX HighTech GmbH (German company)They can make similar fibers (nail heads on the both ends).

Delivery of shot fibers (about 100 mm in length) with nail heads delayed. A head was attached. The other one will be attached.

E. Mojorana visited IMPEX on the last week and summarized report.R. DeSalvo and A. Bertolini visit IMPEX on this week.(They also discuss sapphire ribbon)

Sapphire fibers

1313

Misc.1. ELiTES meeting : 3rd and 4th of Oct. Program https://events.ego-gw.it/indico/conferenceTimeTable.py?confId=2#all.detailed

We have other meeting on 5th of Oct.

2. Y. Sakakibara paper (cryogenic duct) is finally published ! Classical and Quantum Gravity 29 (2012) 205019

http://iopscience.iop.org/0264-9381/29/20/205019