1. MINOS Detector Scintillator Module Construction Methods
Jim Grudzinski
Mechanical Engineer
Argonne National Laboratory
High Energy Physics division
(for the MINOS Collaboration)

2. Some Motivation
The MINOS detector has a very large solid scintillator area-28,000m2 (0.3kT)
8x times larger than anything previous (Grand Sasso -3600m2)
This size could only be accomplished with improved strategies
Extruded Scinitillator
High Quality WLS fiber
low cost multi-pixel PMT’s
Efficient and low-cost production techniques

3. Some Design Considerations
4445 Modules required
3782 Far Detector, 4 types plus two mirror images, 20- to 28-strips wide, 8m long
573 Near Detector, 8 types plus 8 mirror images, 16-, 20-, and 28- strips wide,2-3.6m long
Flexible assembly methods required to accomodate variety in size and geometry
Quality and consistency needed for large scale production
Cost kept down through lower cost student labor
Unskilled (initially) labor

4. Far Detector Module Types

5. Near Detector Modules

6. Module Parts Stamped Aluminum Covers
Machined manifold include fiber grooves to maintain minimum bend radius but also compensate for scintillator width tolerance
Variable width seal adjusts to completed module width which could is allowed to vary by +/- 10 mm
Holes in manifold used for alignment in assembly and surveying during installation

7. Module Parts

8. Manufacturing Optimization of MINOS Modules
Enabling
technologies
Driving
constraints
Component
Solution
Base manifolds
Cost
Size
Detail
Machined
Foamed PVC
NC router
Manifold covers
Cost
Size
Fire safety
Sheet metal
Laser cutting
NC forming
Light inj manifs
Var width seals
Cost
Detail
Inj molded
noryl plastic
Mold flow sim
CAD opt
Light cases
Light seal
Cost
Fab time
Size
Safety
Roll formed
sheet metal
Custom
designed
crimper

9. Construction Sequence Overview

10. MINOS Module Assembly Equipment
Scintillator cutting station
Forming Station
Assembly trays
Module curing racks
Fiber gluing machine
Connector flycutter
Module Crimper
Module Source Mapper

11. Scintillator cutting station
Fixturing to locate cutting guide depending on module type
Cut accuracy +/-1mm over 8000mm.

12. Module Assembly Trays
4’ W x 30’ L Aluminum Hexcell sheets, edges filled with body filler
Hexcell provides stiff support while remaining relatively light allowing much structure to be eliminated from moving module storage racks
Fitted with fixturing bushings and vacuum manifolds for assembly
Results in repeatable assembly to within 1mm over 8000mm.
Provide easy means of module transfer between assembly stations/steps
Integral Vacuum ports

13. Bottom Light Case Forming
Hand slitting tool to compensate for scintillator width variation
Hand forming tools
Table fixturing the same as assembly trays for hole punching

14. Assembling Bottom

15. Assembling Bottom (cont.)

16. Module Curing Racks 4 indexing shelves Rollers on shelves
Overtravel limit switches
120VAC housed in conduit, seal tight , and approved enclosure
Racks mounted on Casters for portability

17. Module Curing Racks (cont.)
Screw jacks raise and lower shelves
4 jacks are coupled to single drive unit
Clamps hold trays in place
Chains,shafts, and couplings fully guarded
Manual motor control with Momentary contact switches

18. Module manipulation
Module trays moved around individually using shuttle tables or in bulk using the storage racks

19. Module manipulation (cont.)

20. Fiber Gluing Machine PLC controlled semi-automatic operation
Applies epoxy, fiber, and tape in single operation
Operator controls on both sides of carriage
Accommodates 8 different type of module geometry
Fiber and glue dispensing tracks scintillator groove

21. Fiber Gluing Machine (cont.)
Operator threads fiber, tape, then starts machine
Gluing quality superior to hand gluing
Carriage motor, glue pumps, cylinders all controlled automatically by PLC
Compliant pushstick key to maintaining fiber low in groove
Able to glue 4 modules per day with a single operator

22. Fiber Gluing Machine (cont.)

23. Top Light Case Assembly

24. Connector Flycutter Diamond bits polish the connector/fiber ends
Converted commercial grinder made low cost high quality solution
Fixturing positively locates the connector

25. Reflector ends
Near Module detectors have reflector ends allowing single ended readout
Precision Stamped plate provides alignment
Hot knife trims fiber perpendicular
Aluminized Mylar tape attached to fiber using optical epoxy

26. Module Crimper
Folds over top and bottom light case into labyrinth seal
9 stations progressively form crimp seal
Mounted to swivel carriage
Carriage manually powered with gear rack and pinion

27. Light Case Crimping Heads

28. Light Case Crimp: Cutaway View

29. Detailing and Light Sealing
Light Injection Manifold Applied
Variable Width Seal
RTV, black electrical tape, and aluminum tape used for light sealing joints

30. Module Mapper Completely automated 137Cs Source, 5miCi
Light injection used to calibrate PMT’s
Approx. 40 minutes to map a far detector module (7-8 per shift)
Continuous scan across X-axis, Y-axis incremented in 8cm discreet steps

31. Results through 2000 modules
Highly consistent results demonstrate quality of the assembly process
<0.2% below 0.5

32. Soudan Underground Laboratory
The Soudan shaft limits objects to a maximum size of 1m by 2m by 9m
Slide courtesy J. Nelson
Photos by Jerry Meier

33. Module Storage and Shipping
Shipping crates had to fit in very tight envelope to pass through mine shaft
Fully loaded crates weighed 5500 lbs
Modules had to be securely held through 360 rotation on trip down mine shaft
Separate crates for perpendicular and 45 degree modules
Factories had local storage to optimize trucking
Eight perpendicular crates fit on one flat bed

34. Module Shipping
Essentially no change after delivery

35. Conclusion
High precision large scale assembly was accomplished using lower cost unskilled labor through creative use of tooling
Assembly trays allowed tight envelope tolerance
Crimping provided reliable and fast light tight seal
Hand forming allowed custom module widths
Automatic mapping required minimal manpower
Laminated assembly technique made stiff modules
Automated Fiber gluing combined with extruded scintuillator produced high quality consistent modules
Resulting Modules show high quality and consistency with 75% of the production complete