BeTev Pixel Detector Mechanical Design by bkx33432

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									           BeTev Pixel Detector
            Mechanical Design.



              Alexandre Toukhtarov.
                    Fermilab,
           PPD / Mechanical- Department.
2/2/2010                                   1
               Introduction.
   The goal of this presentation is
   a) to give an overlook view on BeTev pixel
     detector conceptual design and major steps
     of pixel detector assembly procedure,
   b) to explain prototype work, that is done,
   c) to explain results of FEA for some detector
     components.

2/2/2010                                      2
Mechanical Support System Requirements.
• The Pixel Detector mechanical support structure
  should have low mass within the geometrical
  acceptance (300x300 mrad2) of the spectrometer.
• The detector needs to be retractable to a distance of 2
  cm from the beam and after each refill, the detector
  has to be moved in position. The reproducibility
  should be better than 50 mm and the relative motion
  must be read out with a precision of 1-2 mm. .
• The whole detector will be placed inside the aperture
  of a dipole magnet with a field strength of 1.6 T; it
  should not have any effect on the magnetic field
  strength.
2/2/2010                                                3
Mechanical Support System Requirements.
             (Continuation)
• The design must take into account that the operating
  temperature of the detector will be on the range
  between –10 degrees C and –5 degrees C.
• The detector must be shielded electronically from the
  circulating beam which is a significant rf source.
  Multiple scattering in the rf shielding (which also
  serves as the secondary vacuum envelope) and exit
  plates should be kept to a minimum and yet strong
  enough to withstand the differential pressure of 10-4
  torr.

2/2/2010                                              4
           Mechanical Support System
           Requirements.(Continuation)
• The pressure inside the “clean vacuum” where the
  colliding beam will go through has to be better than
  10-7 torr. The differential pressure between the
  “clean” and “dirty” (where the pixel detector resides)
  vacuum has to be no more than 10-4 torr.
• The two halves of the detector must be aligned to each
  other with an accuracy better than 50 mm in x and y,
  and 200 mm in z (longitudinal direction).
• The individual half planes must be mounted with a
  precision of 20 microns or better, and the positions
  known to 10 microns before the half-planes are
  inserted in the vacuum container.
2/2/2010                                              5
Mechanical Support System Requirements.
             (Continuation)
• The System must include some means of alignment
  monitoring online.
• The system should be stable to within 2 um during
  data-taking.




2/2/2010                                              6
      Pixel Detector Conceptual Design and
      Detector Assembly Procedure. General
                      Notes.
  1. Some small fitches like screw holes,
     screws, bolts, washers and nuts omitted.
  2. Some components have a simplified shape.
  3. Present design based on using of Be
     substrate. Using of another substrate
     options will require some modifications on
     detector design.


2/2/2010                                          7
2/2/2010                                               8
           Assembled Half -Plane & Support Brackets.
2/2/2010                             9
           Half- Support Cylinder.
2/2/2010   Assembled Half –Support Cylinder.   10
2/2/2010   Assembled Half –Support Cylinder   11
              (View From Another Side).
2/2/2010                               12
           Half- Plane Installation.
2/2/2010                                                        13
           Half- Plane Installation (View From Another Side).
2/2/2010   30 Half- Planes Are Installed (Only 4 Are Shown).   14
2/2/2010   30 Half- Planes Are Installed (Only 4 Are Shown).   15
                       View From Another Side.
2/2/2010                                                16
           All Flex Cables Are Attached to PC- Board.
2/2/2010                                                         17
           Flex Cables Are Attached to PC- Board (Close Look).
2/2/2010   Assembled PC- Board. View From “Beam   18
                          Side.”
2/2/2010                                                  19
           Assembled PC- Board. View From Another Side.
2/2/2010                                                        20
           RF- Shield and Displacement Sensors Are Installed.
                 It made of 150 micron aluminum foil




2/2/2010                                               21
           RF- Shield.
2/2/2010                                                        22
           Two Pixel Half- Planes Are In Front of RF- Shield.
2/2/2010                                   23
           Pixel Detector Vacuum Vessel.
2/2/2010   The First Half- Detector Is Inserted Into   24
                      Vacuum Vessel.
2/2/2010                                        25
           First Half- Detector Is Installed.
2/2/2010   Second Half- Detector Is Inserted Into the   26
                      Vacuum Vessel.
2/2/2010   Second Half- Detector Is Installed Into the   27
                       Vacuum Vessel.
2/2/2010                                                  28
           All Pixel Detector Components Are Installed.
2/2/2010                                        29
           Pixel Detector Is Ready for Tests.
2/2/2010                                                     30
           Pixel Detector Is Installed on the SM-3 Magnet.
       Prototype of Support Half- Cylinder.

 • The goal of this prototype work was the
   verification of manufacturing and
   assembly technology and procedure.
 • Prototype has about 1/3 of the real cylinder
   length and correct cross section sizes.
 • Each prototype component has specified
   by design carbon fiber ply layout.

2/2/2010                                      31
One shell is ready
to go.

                                                          The ribs are
                                                          cut out from
                                                          this blanket.




      2/2/2010                                                  32
                     Dave Butler Demonstrates His Work.
                                      Half- Cylinder Skeleton




  Assembled Prototype of the
  Half- Cylinder




2/2/2010                                                        33
                   Another Half- Cylinder Photos.
           Prototype of Pixel Half- Plane
                 Support Brackets.
• The goals of this work were.
a) The verification of manufacturing and
   assembly technology and procedure,
b) Definition of bracket mechanical strength by
   load test and comparison load test results with
   FEA prediction.
• Prototype has real size, each prototype
   component has specified by design carbon fiber
   ply layout.

2/2/2010                                         34
                  Manufacturing Tools




             Some Parts of Support Brackets

2/2/2010   Support Bracket Prototype Parts and   35
                 Manufacturing Tools.
2/2/2010   Assembled Half- Plane   Two Installed Half- Plane   36
                Prototype.         Prototypes.
     General Notes On Half- Plane Support
             Brackets Load Test.
• Known loads were applied at known points on
  half- plane dummies
• Tooling balls on half- plane dummies and
  support half- cylinder prototype were used to
  measure deformations in support brackets
• Tooling ball displacements were compared
  with FEA predictions


2/2/2010                                      37
2/2/2010
           Jorge Montes “Teaches” CMM to Take Measurements.
                                                         38
Sphere #37                                              Sphere #23




                                Load




                                    Sphere #21
     2/2/2010   Close Look on One of the Half- Plane.      39
                                                    Sphere #21: Y-displacement


                     0.000
                                     50                               110                                                   200



                     -0.050               -0.0470
                                          -0.060



                     -0.100                                                   -0.104
                                                                                                                                                      Sphere #21
Y-displacement, mm




                     -0.150
                                                                              -0.158


                                                                                                                              -0.188
                     -0.200




                     -0.250


                                                                                                                              -0.283
                     -0.300
                                                             Load in Y-direction, g
                                                                                                                                       Sphere #23: Y-displacement
                                                              Measurement                              FEA

                                                                                              0.000
                                                                                                             50                                          110                   200


                                                                                                                  -0.0338
                                                                                                                  -0.042
                                                                                              -0.050


                                                                                                                                                            -0.074
                                                                         Y-displacement, mm




                                                                                              -0.100
                                                                                                                                                            -0.112




                                            Sphere #23                                        -0.150
                                                                                                                                                                                 -0.135




                                                                                              -0.200
                                                                                                                                                                                 -0.207




                                                                                              -0.250
                                                                                                                                                Load in Y-direction, g

                                                                                                                                                 Measurement             FEA




                              2/2/2010                         Excel Charts With Some Results for                                                                                40
                                                                      Spheres #21 and #23.
             RF- Shield FEA.
              General Notes.

•   RF- shield material is aluminum.
•   Thickness of central portion is 0.15 mm,
    outer elements made of 0.50 mm thick
    aluminum.
• Two cases were considered:
      -4
a) 10 Pa Pressure from “detector” side;
       -3
b) 10 Pa Pressure from “detector” side.


2/2/2010                                       41
                                     ~0.071 mm
0.109 mm




2/2/2010                                               42
           Displacement Plot for 10^-04 Pa Pressure.
                                     ~0.71 mm
1.10 mm




2/2/2010                                               43
           Displacement Plot for 10^-03 Pa Pressure.
2/2/2010                                                   44
           Von Mises Stress Plot for 10^-04 Pa Pressure.
2/2/2010                                                   45
           Von Mises Stress Plot for 10^-03 Pa Pressure.
                   RF- Shield FEA.
                    Main Results.
 •         Main factor for definition about RF-shield
           design acceptance is displacement.
 •         Present RF-shield design has acceptable
           displacements for 10^-04 Pa pressure.
 •         FEA made for ideal RF-shield model, so
           bigger displacement is expecting for real
           part. To make decision about final design,
           the real displacement has to be measured on
           RF-shield prototype.

2/2/2010                                             46
       Vacuum Vessel & PC- Board Back
          Plates FEA. General Notes.
• The main goal of FEA is define displacement of Vacuum
  Vessel in places were Half- Detector Actuators attached.
• Vacuum Vessel and Back Plate made of stainless steel.
• Simple “shell” models used.
• Back Plate connected to vacuum vessel by means of shoulder
  screws.
• Atmospheric pressure and load from known detector
  components applied to Vacuum Vessel & PC- Board Back
  Plates.



2/2/2010                                                   47
Vacuum Vessel.
Made of 25-30 mm
Stainless Steel
Plates.




                                            PC- Board Back Plate.
                                            Made of 13 mm thick
                                            Stainless Steel Plate.




 2/2/2010   Shell Vacuum Vessel & PC- Board Back Plate Model. 48
2/2/2010   Displacements Plot. Overall View.   49
                             Actuator Positions




2/2/2010   Displacements Plot. Vacuum             50
                Vessel Top Plate.
     Actuator Positions




2/2/2010              Displacements Plot. Vacuum   51
                         Vessel Bottom Plate.
                 Conclusion
• We are fare away from the detector final design.
• The vacuum and cooling subsystems are not yet well
  defined, it can have a big impact on the present
  design.
• Extensive engineering and prototyping work is
  needed on following detector components:
- RF-shield;
- Flex cable;
- PC- Board;
- Substrate-to-Main Manifold flex tube joint;
- Most difficult assembly procedure steps;
- Assembly fixtures.
2/2/2010                                               52

								
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