Repot for the LED calibration system

related to the box mechanics

19 April 2021, SFGD mechanics meeting

Takuji Arihara (TMU) and Tsunayuki Matsubara (KEK)

1. Production readiness check with the box design - Ongoing

2. Assembly procedure to the box - Ongoing

3. Screw strength estimation & choice - Asking for advices

Topics

2

LGP module is almost ready for mass production

Drawings of those

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2 3 4 5 6 7 8

1 2 3 4 5 6 7 8

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Dept. Technical reference Created by Approved by

Document type Document status

Title DWG No.

Rev. Date of issue Sheet

2021/02/18

1/1

bottom_jig_LGP_assembly_v2

松原 綱之

81.1 81.1

141.7

81.7

41.219.9519.95

9.65

236.

924

7.2

247.

225

0.05

8.5

Ø3.2

Ø3.2

Ø3.2

Ø3.2

Ø3.2

51.5

14.8 14.8

8.5

14.5

14.5

8.8

51.514.8

Ø3.

2

Ø3

Ø3

41.2

41.2

41.2

8 6 10

41.2

41.2

41.2

41.2

51.5

15.115.1

20.2520.25

39.

95

236.

924

7.2

247.

225

0.05

8.8

1060

.1

999.

5

1000

.1

Ø3

Ø3

Ø3

製作物2-1

製作物2-2

寸法確認対象物2

・素材、用途、備考は寸法確認対象物1と同様。

・対象物2は1に比べて長いため、その分ジグが長くなる。

・下側のタップ穴位置が1 mmだけ対象物1と異なるため、製作物2-2の構造も1-2と異なる

・上側のタップ穴位置も0.01 mmだけ対象物1と異なるが、対象物の違いよるもので設計通り

1

A

2 3 4 5 6 7 8

1 2 3 4 5 6 7 8

B

C

D

E

F

A

B

C

D

E

F

Dept. Technical reference Created by Approved by

Document type Document status

Title DWG No.

Rev. Date of issue Sheet

2021/02/18

1/1

wall_jig_LGP_assembly_v2

松原 綱之

586.

4

41.219.95

9.64

19.95

14.8

51.5

14.8

7.5

291.

727

7.56

81.1

7.8

291.

727

7.56

9.94

81.7

20.2541.2

20.25

41.2

141.7

41.2

51.515.115.1

7.5 14

.5

7.814

.5

14.8

Ø3.2

Ø3

51.5

製作物1-2

製作物1-1

寸法確認対象物1

・製作物は全てアルミ製。対象物はプラスチック製。

・製作物1-1は、対象物の外形寸法の四方が設計より+0.3 mm (+ジグの製作精度 0.1mm程度) 以内に収まっていることを確認するのが主目的。厚さ8mmの対象物を深さ3 mmに収める。

タップ穴の位置は、実際に取り付ける先の理想的な位置に設計してある。

開口部を大きくとっているのは、対象物 (2枚の板を内包) の内側寸法を確認するため。

・製作物1-2は、対象物とともに取り付けて内側の寸法が確保されていることを確認する。

・対象物を傷つけないための面取りや、コーナーの刃の逃げはまだ構造に反映していない。

587

647

Ø3.2

Ø3.2

Ø3.2

Ø3

Ø3

1038 81.1 6

Jigs for the dimension checkFinal prototype

We would like to have a compatibility check with the box design. ̶> 2D box drawing to make sure the hole positions, etc…

3

3D CAD of the right panel from Adamo

I plan to check the screw and fibers hole positions on the panel to check consistency.

4

Assembly procedure to the box

~70 cm

• Minimal changes of boundary condition after fiber insertion.• Access to bottom of the detector for fiber cutting and attachment of the LED

calibration system.• Mounting of the electronics for commissioning on the ground.• Stage height less than 2 m from the floor to avoid the high-place work in the

J-PARC safety rule.Since the requirements are different from the stand for the scintillator cube as-sembly in CERN, a dedicated stand must be designed[5]. The baseline design ofthe stand is the baby basket shape as shown in Fig. 8. The design must be deter-mined considering the ease of work, safety, and the possible interference with theassembly platform.

Stand

Figure 8: Baseline design of the stand.

3.2 Fishing line removal and fiber insertion (Responsibility: Kyoto, KEK)

The first part of the assembly work in Japan is the removal of the fishing lines andinsertion of the WLS fibers. The WLS fibers for the Super-FGD were deliveredfrom Kuraray. They are now being assembled in Hayashi-Repic Co., Ltd[6]. Theassembly includes cutting the fibers to a few cm longer length than the actuallength in the detector, attaching a dedicated optical connector in one end of thefiber and polishing the fiber end by a diamond cutter. The assembled fibers arelodged in plastic cardboards and delivered to J-PARC as shown in Fig. 9. Thefishing line removal and fiber insertion will be the most tough work since 56,384fishing lines and fibers must be removed and inserted one by one. The fibers mustbe inserted until the optical connectors are mounted on the holes on the platesas shown in Fig. 10. Between the optical connectors and the plates, soft formsneeds to be installed to improve the optical coupling between the fiber end andMPPC (Fig. 11). Thus, this soft form must be set on the box plate before the fiberinsertion. In addition, we have to be very careful not to damage the fiber.

8

3.5 LED calibration system attachment (Responsibility: TMU, KEK)

3.5.1 INTEGRATION DESIGN

The LED calibration system is used for a real-time calibration such as MPPC gainduring the detector operation by emitting several photo-electrons of light level toall channels [7]. It consists of 46 modules in bottom and 47 modules in side asshown in Fig. 17. Each module has an black acrylic container that contains a LightGuide Plate (LGP), a diffuser plate together with a small 7-LEDs array board andlight collimator.

Figure 17: Integration design of the LGP modules on the box surface.

The bottom and side modules are 999.5⇥81.1⇥8.0 mm3 and 586.4⇥81.1⇥8.0mm3 in dimension and has ten and six clearance holes, respectively (Fig. 19).There are corresponding screw holes in the box plates in bottom and side walls,and the modules are attached by screws. Small coaxial cable (U.FL cable, 1.13 mmdiameter) is used from the LED array board in the module to LED driver boardat SS floor. Cable routing around the detector is shown in Fig. 19. Light barrierdesign is to be determined, while it will be similar and simpler design than thatfor the MPPC region.

Figure 18: The bottom and wall module prototypes, and a countersunk screw tobe used for the module fixation against to the box plate.

14

What we performed: ・Work time for module mounting was estimated. ・Workability with the creeper was checked. → ~1 week work with two persons (Preliminary)

To do: ・Light barrier for the calib. system is to be investigated ・The QC procedure to be optimized with other works ・Assembly stand to be designed (Also for Fiber/MPPC assemblies & electronics crates)

We are trying to summarize the assembly procedure in a document. First version to be released with other steps like fiber and MPPC assemblies

5

Table 2: Summary of the attachment works

Working process Workers Time [h] Comment1. Bottom module screwing 2 6 Work at the bottom2. Attachment check of those 2 3 Work at the bottom3. Wall module screwing 2 54. Attachment check of those 2 25. Bottom module cabling 2 26. Wall module cabling 2 27. Cable connectivity check 2 4(TBD)8. Bottom light barrier attachment 2 6 Work at the bottom9. Wall light barrier attachment 2 410. Light tightness check 2 8(TBD) Work at the bottom

• Second step (process #5 to #7) is the cabling around the box. We will con-nect the U.FL cable connector to the 7-LED array board located at the endof module. Basically we can work from the detector side. Looking fromthe bottom may be sometimes needed to check connectivity. We estimated 2minutes per module for checking the cable number and connection. There-fore, total 2 hours are estimated, respectively. Cables are already assembledin the heat shrink tube with a unit of 12 cables ⇥ 8 bundles. The tube shouldbe glued to the G10 layer up to the detector bottom corner. Extra length willbe routed after installation into the basket. While the length is not deter-mined (about 5 meters, probably?), the remaining cable bundles should bemanaged and temporary fixed to a location that will not disturb the installa-tion. Test with LED should be performed before the light barrier attachment(TBD).

• The third step (process #8 to #10) is the light barrier attachment. The designis not yet determined but we currently assume the working time of 7 (6) min-utes per module. The estimation should be updated later. The light tightnesstest should be performed with MPPC64-PCB in the end, while it should beconsidered later (TBD).

3.5.3 RISK ANALYSIS AND ASSESSMENT

For the installation of the bottom modules, the workers must go below 2 tonsof the detector. In addition to wearing a helmet, some human protection framewould be useful. Working glasses can protect a possible drop of the screws ortools. (Comment: To be addressed more carefully. It could be similar to the

16

Thermal expansion effectMotivation: Robustness check of the LGP module screwed to the box by FEA

FEA results: ・Local maximum of the deformation is ~0.5 mm (equivalent to 3x10-5/℃) ・Local maximum of the von-Mises stress to the RENY screw is ~300 MPa (The mesh size is too rough → Next page)

Container (Acrylic)LGP (Acrylic)

Diffuser (Acrylic)

G10

Countersunk screwFixed

~1 m

https://www.chemis.co.jp/products/item?id=270000200060

Studied by Arihara-san (TMU) ・FEA: ANSYS student 2021 R1 (A number of nodes is limited to 128k) ・Structure: Bottom LGP module (See right drawing) ・Temperature change: 25℃ → 10℃ ・Boundary conditions: 　・Upper surface of the G10 (3 mm thickness) is fixed. 　・Countersunk screws (M3) are bonded to the G10 hole as well as the container. 　・Other components are not bonded.

6

Total deformation amount Stress dist.

Evaluation of the stress to screw・Updated FEA results for the von-Mises stress by applying 0.5 mm displacement applied to the screw head

2021/4/5 - RENY/ +

https://www.chemis.co.jp/products/item?id=270000200060 3/5

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・On the other hand, share stress (σ) is formulated as follows: σ [N/mm2] = F [N] / As [mm2] 　where, As is an effective cross-sectional area (As = 5.03 mm2 for M3 screw), and F is a share load 　(F = 853 x 0.6 N (Tensile rupture force for the M3 RENY screw & conversion factor to share force.) ・Then the (naive) share stress to be allowed is calculated as ~100 MPa (Structural effect and safety factor are not considered.)

827 MPa

<100 MPa

becomes higher than previous page but more localized

Countersunk screw G10 layer Diffuser LGP Container

New FEA setup around the screw only

Not sure whether this estimation is reasonable or not. Any advices?7

Stress distribution

Another option to use Titanium alloy screw?

・The maximal deformation becomes smaller than RENY (~0.5 mm → 0.35 mm) ・The von-Mises stress is higher than RENY (Max. 827 MPa → Max. 1714 MPa)

We also investigated beta titanium alloy (Ti-15V-3Cr-3Al-3Sn) ・Higher share load: F = 4416 [N] (853 [N] for RENY) → The (naive) share stress to be allowed is calculated as ~530 MPa ・Rigid material (Young’s modulus: 88 GPa (19.6 GPa for RENY) ・Light metal (Specific gravity: 4.8 (1.65 for RENY)

FEA results in the same way as RENY case~1700 MPa

<300 MPa

https://hirosugi.co.jp/technical/material/BTi.html

Due to the more rigidity, the situation is not so improved w.r.t. the RENY case8