MICE Collaboration meeting at CERN March 28 – April 1, 2004

1. MICE Collaboration meeting at CERN March 28 – April 1, 2004 MICE Cooling Channel alignment & tolerance Issues Wing Lau– Oxford

2. Control of the vessel tolerance We believe…… The control of alignment and its tolerance of the magnet & coils should come from the tolerance control from the outer vessel, which is formed by rolling a plate into shape and joined up by apply a longitudinal seam weld. The tolerance in a rolled vessel is dominated by the control on its circularity which is largely affected by the rolling process, and the thermal deformation on its closing seam weld. As a result, the non-circularity effect is quite un-predictable To overcome this, we suggest the follow manufacturing schemes:-

3. Finished shape of a rolled vessel Closing seam weld

4. Ideal shape of the finished vessel

5. The circularity deviation

6. Welding an oversize flange ring at the two vessel ends

7. Machining the outer rim of the flange to be concentric to the true centre of the vessel

8. The outer edge of the flange can bemachinedto be concentric to the true circle of the vessel The true circle of the vessel True centre of the vessel The finished shape of the rolled vessel

9. Weld nozzle stubs to vessel shell

10. Machine stub face reference to the true centre of the vessel

11. Attach Cold mass to the machined stub. Cold mass is now at the true centre of the vessel

12. Typical concentricity :+ 0.5mm on each end flange Typical angular tolerance achievable: <+1 mrad over the vessel length Typical manufacturing tolerance of a vessel using the flange rings as a datum and all the attachment points machined referenced to that datum

13. Max total accumulated in-plane misalignment at the end of the MICE channel =+5.67 + 4*0.5 + 1749 *tan 0.057= +9.42 mm Max. in-plane misalignment at the RH flange of mid Focus Coil= + 0.5mm + 421* tan 0.057o = + 0.92 mm How to work out the accumulated tolerance Mid Focus Coil RH Coupling Coil RH Focus Coil Matching coil Detector coils Max. accumulated in-plane misalignment at the RH flange of Coupling coil vessel= + 0.92 + 2* 0.5mm + 1908* tan 0.057o = + 3.82 mm Max. accumulated in-plane misalignment at the RH flange of end Focus coil vessel= + 3.82 + 2* 0.5mm + 842* tan 0.057o = + 5.67 mm

14. Imbalanced magnet forces Alternatively……… If we can pass the load to the floor, then the modules can be individually aligned. This eliminates the tolerance accumulation.

15. Summary Conclusion By fixing the individual module to the floor, we can avoid the accumulation of tolerances. The recent reduction in magnet forces makes this more feasible than ever. That being the case, the tolerance is extremely small (a couple of mm for each individual module). Even if we have to join the modules up, the accumulated tolerance is still under +/- 10mm for the entire cooling channel. • The acceptable tolerance from Ulisse’s calculation is :- • In-plane+ 3mm • Angular+ 6 mrad • This equates to a total in-plane tolerance of+ 3 + 5762 * tan 0.3437o= 37.57mm • On the bases of this, the machining tolerance is well within the physic’s requirement