1. Platform Design for the Target Spectrometer using Heavy-Weight Rollers J. Lühning, GSI Darmstadt,
Three design goals for Platform:
Low construction height
Free choice of position in beam direction
Support for Backward-EMC
CM March 2010

2. CATIA FEM Model Parabolic tetrahedrons
Several separate parts interconnected by stiff spring constants
Height of platform beams (blue) 550 mm (Euro-Norm IPE-550)
Height above floor 300 mm
Distance between longer beams 4500 mm
Length of connecting beams 7900 mm
Support for the Backward-EMC attached to the upstream beam
Distance between center-planes of barrel beams 3100 mm
CM March 2010

3. Bearings Platform bearings:
Either 4 hydraulic jacks (with locknuts) or 4 rollers
Distances between bearings aim at minimizing stresses (and deformation)
CM March 2010

4. Von-Mises-Stresses in Support Structure
Assumptions:
weight of barrel yoke with detectors 210 t
weight of doors 100 t
weight of the support structure, pumps, and other equipment around the barrel 30 t
doors in closed position
BW-EMC (1 ton) in operating position
The stresses are far below the yield strength of ordinary structural steel which is about 240 MPa.
CM March 2010

5. Deformation with Open Doors
Vertical deflection at ends of long IPE-beams 4 mm
Compared to case with closed doors the barrel is lifted by ~0.3mm
Bigger effect on BW-EMC-support Δy = +4 mm, Δz = -8 mm (low torsional rigidity)
Support rods put beneath ends of long IPE-beams would reduce deflections
CM March 2010

6. Special requirements
Horizontal acceleration: For 1.5 m/s² the maximum stress in the presented model stays below the tensile strength of ordinary structural steel
For an unevenness of 4 mm over 4 meters in the moving area the maximum stress stays below the yield strength of 240MPa
One IPE-beam cut and reinforced like shown above gives an access gap height of 83 cm
CM March 2010

7. Stresses On Floor Thickness of concrete 1 meter Crane rail
Load 100 tons
CM March 2010

8. Connection between barrel support and platform (at least 4 joints)
Open Questions
Welding seams
Connection between barrel support and platform (at least 4 joints)
Connection between platform and rollers
Floor (evenness, strength, position of rails)
Guidance of platform
Height of rails
Fine positioning of Target Spectrometer
CM March 2010

9. Conclusions and Remarks
If heavy weight rollers are chosen to move the Panda Target Spectrometer, a platform made of IPE-550 beams would be suitable. 4 hydraulic jacks or rollers, respectively, would be sufficient to bear all the weight.
Long-stroke hydraulic jacks are a cheap solution to drive a roller-supported platform. Disadvantages are slow speed and laborious work.
For the Backward-EMC, a support could be attached to the platform. It seems possible to reduce the deflection of the EMC during movements of the doors or of the whole platform to less than 1 centimeter.
If the platform would have to bear the Muon-Filter in addition, it would either have to be much stiffer or it would require more supporting jacks/rollers, making the alignment and movement more cumbersome.
CM March 2010

10. Some Links
Rollers:
Bearings for positioning:
(pot bearings)
CM March 2010