1. MDI Issues M. Sullivan For
M. Boscolo, K. Bertsche, E. Paoloni, S. Bettoni,
F. Bosi, P. Fabbricatore,
P. Raimondi, M. Biagini, P. Vobly, I. Okunev,
A. Novokhatski, S. Weathersby, et al.
SuperB Meeting XVII
La Biodola, Isola d’Elba, Italy
May 28 - June 2, 2011

2. Outline MDI Issues Next Steps Summary and Conclusions Cryostat size
SVT services and cables
Shielding needs
Support structure for the cryostats
Vibration control
Rapid access to SVT
Next Steps
Summary and Conclusions

3. Cryostat size
We need a first approximation of how much space the cryostat needs – especially radial
This sets the inner radius of the DCH
We also need to understand how to get the SVT services and signals in and out – this includes the cooling for the inner Be chamber
And of course the W shielding in this area
I’m guessing we may not like the answer

4. IR layout

5. Cryostat size (2)
Notice in the drawing on the previous page that the beam lines are quickly diverging – much more than what we had in PEP-II
We also need solenoid compensation that cancels the entire detector field out from 0.5m

6. Supports for the cryostats
We need someone to start designing the supports for the cryostats
P. Fabbricatore has done some preliminary magnetic force estimates because he needs to transfer these forces from the magnet cold masses to the cryostat body
How we externally support these cryostats is connected to how we move the cryostats to obtain rapid access to the central region

7. Supports for the cryostats (2)
The cryostat supports also need to minimize vibration transmission and should hopefully dampen ground motion
We have some design criteria from Kirk Bertsche for these supports

8. Background hot spots
We have heard that a background hot spot has been identified as coming from the beam pipe between the QD0 and QF1 magnets in the cryostat
This is a very difficult region to add extra shielding so we should verify that the background calculation is correct
Space inside the cryostat is very cramped already and adding shielding may in fact force an increase in the outer radius – an unwanted consequence

9. Bkgd hot spots (2)
As background calculations improve new hot spots may show up – we will have to take a close look at these new hot spots and figure out the best way to handle each case
Shielding near the hot spot
Shielding near the detector
Redesigning the masking and/or beam pipe
Introducing more masking upstream

10. Next steps Engineering support for cryostat supports
Background generation cross-checks with simpler programs whenever possible
After getting preliminary engineering requirements for
The permanent magnets
The final focus magnets (QD0 and QF1)
The cryostat bodies and
The cryostat supports

11. Next steps (2)
We then need to redesign the IR incorporating as many of the new engineering constraints as possible and then work together with the engineers to hammer out solutions to remaining conflicting requirements
Then after this is done we should have something that can be written up in a TDR

12. Next steps (3) This is not the end of it though…
As the engineers and designers work out the details of the design (how many bolts are needed here how does one assemble this joint there, etc.) we will together encounter more detailed problems
It will also be true that background and physics simulations might uncover a problem here or there

13. Next steps (4)
It is particularly important that the various design engineers keep in close contact with each other and with the physicists especially when a particular group is developing a design with hardware close to an agreed upon boundary
Many times a group assumes that there is space just outside of where their hardware is which allows them to assemble their hardware

14. Next steps (5)
Compromise without sacrificing performance is the name of the game
When things get tight prototyping becomes an important part of the decision making process
Keep in mind that although we physicists want to fill all space with something useful there are times when adding a clever fancy gizmo just because “it would fit nicely right here” is not the right answer

15. Summary
We have a good “starting point” IR design that meets our requirements
Now the engineers can come in and tell us what is impossible
Then we need to decide how to change the design with the guidance of the engineers so we can still build what we want
We may have to compromise some of the IR parameters…

16. Conclusion We are at a good starting point…
Now the fun (and hard work) begins!