Application for KAGRA (LCGT) Membership
Jun Xu, Jingya Wang, Lihe Zheng, Huili Tang
Shanghai Institute of Ceramics, Chinese Academy of Sciences
The KAGRA (LCGT) Face-To-Face Meeting, ICRR
Feb 2-4, 2012
Applicants
•
•
•
•
Jun Xu: Group Leader
Jingya Wang: Machining Research
Lihe Zheng: Measurement Research
Huili Tang: Crystal Growth Research
Outline
I. Background
II. Motivation
III. Proposed Works
1.
2.
Large-Size Sapphire Crystal Growth
Detection & Machining of Large-Size Sapphire Crystal
IV. Facility
V. Human Resources
VI. Summary
I. Background: Core optics of KAGRA
f2f meeting, 3 Feb. 2012, Norikatsu Mio, University of Tokyo
ETMY
Mirrors for Main cavities
Initial: Silica
Final: Sapphire
f10cm
Laser
MC1
MC3
MT1
PRM
PR2
ITMY
ITMX
MT2
BS
PR3
SR2
MC2
f38cm
Large-diameter mirrors
SR3
SRM
ETMX
I. Background: Requirements for Sapphire Crystal
SHNU-LCGT Round Table Meeting, 19 Aug. 2011, Takaaki Kajita
II. Center Activities and Motivation
1. Sapphire crystal research center located in SIC, CAS was founded in July,
2010, aiming at large-size sapphire crystal growth by different crystal
growth methods such as KY, EFG, HEM, Cz and TGT.
2. Sapphire crystal research center has strong interests on the experimental
challenges of largesize sapphire crystal, led by Prof. Jun Xu from
Shanghai Institute of Ceramics, CAS.
3. Experiences in large-size sapphire crystal growth, annealing, detection,
cutting and grounding, as well as the home made facilities.
To provide manpower for crystal growth experiments
and management to meet the optics requirements of
KAGRA (LCGT) .
II. Center Activities
Permanent members (16 now)
• Jun Xu (Shanghai Institute of Ceramics, CAS)
Leader of SIC-KAGRA (LCGT) Collaboration
Experimental:
• Growth Parameters (6)
----To optimize the growth parameters and verify the lab
designed facility and thermal simulation.
• Cutting & Grounding (3)
II. Center Activities
Permanent members (16 now)
Thermal Heater Design (2):
----crucial for obtaining high quality crystal. To obtain
homogeneous temperature gradient with improved
heater and rectangular shielding set-up.
Furnace components, Mechanics, Vacuum and system
heater (2):
----Furnace components: attain high temperature and
high vacuum.
II. Center Activities
Thermal Simulation (2):
Thermal Simulation: Temperature distribution mode (WT50)
WT50 limited gridding
WT50 model
WT50 simulation results
(2810 units, 1467modes) for thermal field
IIA. Memorandum
– Memorandum on
Academic Exchange
between the Institute for
Cosmic Ray Research,
the University of Tokyo &
the Sapphire R&D Center,
the Shanghai Institute of
Ceramics, CAS has been
signed up by Jun Xu &
Takaaki Kajita on January
8th , 2012.
IIB. First Samples sent for Absorption
Measurement in KAGRA
III Proposed Works:
Progress of Sapphire Crystal Growth
Verneuil
10-20mmt
Abrd
China
HEM
125mmt
CZ
100mmt
1890
HEM
340mmt
65KG
1970
VGF
80mmt
TGT
120mmt 8KG
KY
300mmt
65KG
KY
220mm
1980
1990
CZ
200mmt
2006KY
260mmt30KG
2000
2011
2011KY
400mmt
85KG
2008KY
350mmt 65KG
Sapphire crystal grown by VGF
TGT: self-possessed initial technology
1.
2.
3.
4.
5.
molybdenum crucible
seed crystal groove is set at the bottom of the
crucible to prevent the seed crystal from melting
temperature field was supplied by the graphite
heater and the cooling apparatus.
Heater cylinder is cut into the shape of
rectangular crate and fastened on the graphite
electrode plate connecting to the water cooled
electrode bar.
TGT with Graphite Heater produced crystals
with rose pink and annealing was required.
TGT: self-possessed initial technology
149mm
118mm
97mm
89mm
69mm
Dia.114mm
Sapphire grown by HEM
By adjusting the Helium gas flow rate
and heater power to control the
temperature gradient, the crystal is
formed slowly from bottom to top by
exploiting the heat exchanger Helium to
bring away the heat and forming the
vertical temperature gradient in the
crystal growth zone.
Sapphire grown by HEM: XRC &
dislocation density
y=y0 + (A/(w*sqrt(PI/2)))*exp(-2*((x-xc)/w)^2)
Sapphire crystal grown by CZ method
1. Easy to view the crystal growth process.
2. Exploit the seed crystal with specific orientation and apply the neck
shrunken techniques to obtain high optical quality crystal with faster growth
rate and higher integrity.
3. Defect caused by the uncontrolled complex liquid activity produced by the
combined actions of forced convection induced by the rotation of crystal and
crucible, together with the free convection arisen by the gravitation.
4. During large crystal growth process, defects are caused by mechanical
perturbation
Sapphire grown by CZ method:
dislocation density & XRC
Sapphire grown by CZ method under polarized
light: mosaic structure & large boundary
Crystal defects such as mosaic structure and lowangle boundary under stress gauge.
Principle of KY method
1. a cold seed crystal is lowered to
touch the melted raw material
2. crystal is started to grow when the
interface temperature is lower than
the melting point
3. lift the crystal stage by stage slowly to
enlarge the exposed surface.
4. crystal was kept clear of the crucible
wall during the growth process and at
the end of growth the inside stress
would be greatly reduced.
5. However, comparatively large heat
thermal shock was produced when
crystal departing from the remaining
fused mass.
Sapphire crystal grown by KY method
Sapphire obtained by KY: dislocation
density & XRC
FWHM (Full Wave at Half Maximum) for the samples at the
center with 11.484’’, edge site 1 with 12.276’’ and edge site 2
with 16.992’’ show that the sample with higher crystal quality
possessing lower dislocation density.
Comparison of different crystal growth method
• Venuil, Cz, Float Zone method: Crystal quality and size are both
limited which can hardly meet the high requirements of optical
application.
• HEM, TGT: Large sized sapphire crystal with good quality can be
obtained where HEM requiring plenty of Helium as cooling carrier
and TGT with Graphite Heater producing crystal with rose pink.
• TGT, KY: Post Treatment such as high temperature annealing is
required although it’s complex and with high cost. The optical quality
of KY crystals are improved after in-site annealing.
Comparison of sapphire crystal
Technology
Dislocation
Density
(Pits/cm2)
FWHM
(″）
Purity
(%)
Impurity
Content
(ppm)
KY
(Kyropoulos)
102-103
<20
99.996
﹤1
HEM
(Heat Exchange
Method)
103-104
CZ
(Czochralski )
﹥103
>20
TGT
﹥103
>15
>15
99.997
99.990
﹤4
IV. Facilities
IV. Facilities
IV. Facilities
IV. Facilities
--Cutting and Grounding for Large Sized Sapphire Crystal
single side grounding
surface finish testing instrument
chamfering machine
Automatic chip mounter
annealing furnace
Spheronizator
roughness measuring apparatus
optical microscope
atomic microscope
flatness inspective meter
V Human Resources
Summary
• We will provide significant manpower and
sapphire crystal resources for KAGRA
(LCGT) experiments.
• Permanent Members = 16
• We are willing to expand our participation to
wider area. Any suggestions are welcome.
Thank you for your attention!
xujun@mail.shcnc.ac.cn; 13501650580
Factors that may affect Absorption Parameters
1.
2.
3.
4.

Impurity
Dislocation Density
Micro-defects: Large boundary
Micro-defects: Low angle boundary
Adjusted by growth parameters and growth
method; Defects in the crystals obtained by
different growth method results in different
emphasizes.
• 60kg: dia240-260 mm: 350 mm thickness
• 80kg: dia260-280 mm: 400 mm thickness