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

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

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

IR layout

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

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

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

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

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

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

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

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

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

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

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…

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