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A cover to protect the KOTO CsI calorimeter
from earthquakesTaku Yamanaka
December 19, 2011Kuno-Yamanaka Group Year-end Meeting
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KOTO CsI Calorimeter
2240 2.5cm x 2.5cm
476 5cm x 5cm
50cm long CsI crystals
Finished stacking on Feb. 10, 2011
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The Earthquakemoved the CsI crystals out by ~5mm
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How do we prevent the crystals from
flying out when the next large earthquake
comes?
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Assumptions
1G horizontal acceleration
4.5g/cm3 x 50cm x 9.8m/s2 = 22kPa side pressure
x3 safety factor = 66kPa
(20t on 2m-diameter surface)
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Bending-force of a hard plate?
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Bending-force of a hard plate?
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Bending-force of a hard plate?
Needs 2cm thick steel plate
~500 kg!
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Tensionof a soft cloth?
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Tensionof a soft cloth?
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Tension and curvature - in case of a string -
8
x
z
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Tension and curvature - in case of a string -
8
x
z
Δx
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Tension and curvature - in case of a string -
8
x
z w [N/m]
Δx
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Tension and curvature - in case of a string -
8
T
T x
z w [N/m]
Δx
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Tension and curvature - in case of a string -
8
T
T
θ2
θ1
x
z w [N/m]
Δx
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Tension and curvature - in case of a string -
8
T
T
θ2
θ1
x
z w [N/m]
Δx
w∆x = T (sin θ2 − sin θ1)
� T (dz
dx(x + ∆x)− dz
dx(x))
w � Td2z
dx2
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co /en
cushncfoss sa?rirn
IOuTen ylen/
,-. . .
Cover made of a strong cloth
Structure to keep parabola
shape
Aramid fabric
Teijin Technora:
T < 170kN/m
Curvature with 10cm bulging can hold the weight
... but only 1m wide
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How to sew fabrics together
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Strength test
Make a fabric loop with sewing
Insert two bars inside the loop
Press the two bars apart with force F
Tension = F/2
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F
5cm
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Strength test
Make a fabric loop with sewing
Insert two bars inside the loop
Press the two bars apart with force F
Tension = F/2
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F
5cm
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Sample made by company14
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Sample made by companyTension
~3kN/5cm
= 60kN/m
< 170kN/m (fabric strength)
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The weft slip.Warp only
The weft are squeezed
Sewing thread push the weft
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The weft slip.Warp only
The weft are squeezed
Sewing thread push the weft
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I tried many sewing methods16
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SolutionMake dead ends for weft
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10mm
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SolutionMake dead ends for weft
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10mm
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SolutionMake dead ends for weft
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10mm
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SolutionMake dead ends for weft
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10mm
Tension ~ 100 kN/m
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Final sewing method for Ver.1Bend two fabrics together in Z-shape
Sew 3 locations x 3 times w/ 3mm pitch
Tension = 100 kN/m = 0.6 x 170kN (fabric)
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DesignSew three 1m wide fabrics => 1 sheet
2 sheets at 45deg
Add sides for securing down to the cylinder
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co /en
cushncfoss sa?rirn
IOuTen ylen/
,-. . .
How to keep the parabola shape
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PVC pipes
40 different types
379 pieces
24Mr. UesawaVice President
Kyoto Jushi-Seiko
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So we removed strings for half a circle, extended the side sheet by 7cm, and hand-sewed it.
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Aug. 19, 2011 3AM= T - 6h
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What we learned
Aramid cloths are strong
They can be sewed together w/ 60% strength
Prepare an length-adjustment mechanism for fabrics
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