1. M. Sullivan SuperB General Meeting Perugia, Italy June 15-20, 2009
MDI (and IR) Summary
M. Sullivan
SuperB General Meeting
Perugia, Italy
June 15-20, 2009

2. Outline Presentations in the MDI session IR topics this meeting
IR beam pipe Sullivan
SVT and beam pipe Bosi
Shielding and QD0/QF1 Paoloni
HOM Novokhatski
IFR backgrounds Cibinetto
IR topics this meeting
SVT L0
L1-4
Cryostats and SVT Assembly
Energy change
Next IR design

3. MDI presentations
Sullivan presented the latest thoughts on the IR beam pipe and Filippo Bosi presented an SVT perspective on the IR beam pipe
Magic flange – a vacuum connection that can be disconnected that is between the cryostats
After looking at all of the “magic flange” designs we realized that these designs rely on the removal of one of the cryostats first, i.e. one could get to the flange either with long tools or with hand wrenches directly.
The Cornell design is most like a true magic flange that can be disconnected with the cryostat present – however the design has o-rings
Come back to this topic in the assembly discussion

4. IP beam pipe
Plan view
Side view

5. MDI presentations (cont.)
Filippo presented current thinking on the beam pipe from the SVT group
Perhaps 300 um thick Be
Au layer most likely on the inside (~4 um)
Cooled at the ends or cooled with a very thin layer of liquid
How much power can we expect?
PEP-II had to cool ~500 W after the extra cooling was added to the bellows at each end
Decided as a working assumption to design for 200 W

6. HOM
Sasha Novokhatski showed a work in progress toward calculating the HOM heating for the IR
He observed that we are making cavities in the region between 3 and 6 m
We will want to install absorbers in this area
There will obviously be HOM power in the IP region from the joining of the two beam pipes to one

7. The Present Design

8. S. Novokhatski

9. Shielding and backgrounds
Eugenio showed the latest on QD0 and QF1 as well as recent work on shielding the DCH from the beam
The shielding became a point of discussion
A large tungsten shield
Weight
Who or what has to hold up this weight
SuperB is very different from PEP-II
PEP-II had a shield around the beam pipe that was at least 10 cm of Fe thick (the permanent magnets)
Eugenio has some first data runs of various backgrounds
Gianluigi Cibinetto presented concerns for neutron backgrounds for the IFR and showed that the neutron rate found for BaBar was already too high for the new IFR detectors

10. IR + SuperB Geant4 Model
IR P3 Modeled in Geant4: beam pipe and magnetic fields
Preliminary look at Luminosity backgrounds:
Beam strahlung from 1400 bunch crossing ( ~ sec )
400k evt. pair production ( ~ sec )
Neutron production included in the sim.
Analysis of this data just started

11. Primary reflected by the
Future activities
Bigger sample production (including Touschek and beam gas contributions):
Shielding thickness optimization (cost benefit considerations)
Shielding external design optimization
Physics window beam pipe optimization
Study neutron production downstream QF1
Primary reflected by the
Tungsten shielding

12. Preliminary Suggested Shielding Scheme
Actual shield simulation is 3 cm thick

13. IR topics SVT and L0 SVT access
L0 attached to the central chamber
SVT mounts to the beam pipe that is part of the cryostats
Very similar to PEP-II
SVT access
Want access to the SVT on a week time scale (instead of months)
We are presently defining the 300 mrad line as the treaty line between machine and detector

14. SVT and Cryostats Fast access to the SVT
KEKB does this and if we plan for this up front we can do this too
We need to put the nearby beam components on rails so we can easily move them out of the way also get the components back into position without having to survey them
According to the previous discussion we do not have an easy way of disconnecting the flanges between the two cryostats
So propose putting the SVT and cryostats together outside of the detector and then sliding the assembly into the detector

15. How to do this?
Backward side needs more thought
We have decided that the cryostats have to be mounted on sturdy supports that mostly likely go down to the floor
There are large expulsion forces and we want minimize vibrations
Now there are also these tungsten sleeves that need to be supported
Propose mounting the W sleeves on the cryostat supports and leave enough room inside the W sleeve for something like rails or a trough that we can use to slide the SVT and cryostat assembly in and out of the detector
This gives us quick access to the SVT (1-4) and to L0 and to the Be beam pipe and to the permanent magnets
If this is planned carefully we disconnect nothing
Needs plenty of thought and attention to details

16. Energy change
The quick access to the SVT gives us also quick access to the permanent magnets
This allows us to reconfigure the machine for other energy running relatively quickly by removing or altering the PMs
It probably still takes a week to 10 days for a complete turn around so we don’t want to do this too often

17. Next IR design
Try to make QD0 as easy as we can without changing too much
This is one of the hardest magnets to build so we should at least make it look better on paper
Stay with our philosophy of using the most aggressive design parameters
7x4 beam energies (larger energy asymmetries are harder)
Smallest beta*s
Largest emittances
Lengthen the cryostat some to cover more of the detector solenoid field with compensating solenoids – perhaps move QF1 out some more

18. Summary
Many good and detailed discussions about the machine and detector interface
Integrating plans are being hatched that look interesting
Quick access
Tungsten shields
Cryostat supports
There will be many more issues to resolve as they surface
IR design work will continue to use aggressive machine parameters in developing new iterations
Good progress!