1. Challenges for FCC-ee MDI mechanical design
BINP
Challenges for FCC-ee MDI mechanical design
A.Krasnov, E.Levichev, S.Pivovarov, S.Sinyatkin
BINP, Novosibirsk
Workshop on the Circular Electron-Positron Collider , 24-26th May 2018, Rome
Workshop, May 2018, Rome

2. FCC-ee IR new design: motivations
BINP
There are following problems with the baseline FCC-ee IR design:
A cryostat does not fit the detector requirement of 100 mrad lost angle.
A space before the cryostat for accelerator components such as beam position monitors, bellows, flanges, etc. can hardly be found.
There is no space for remotely controlled flange and hence the procedure of the IR assembling is not clear.
Contribution of the compensation solenoid field in the vertical emittance excitation is rather high.
Taking above into account we consider an alternative design discussed below.
Workshop, May 2018, Rome

3. 3D conceptual design Interaction Region.
BINP
100 mrad cone IP
Anti solenoid.
Correction coils IP
QC2 Cryostat
QC1 Cryostat
LumiCal
Workshop, May 2018, Rome

4. 3D conceptual design Interaction Region.
BINP
QC2.2
QC2.1
QC1.3
QC1.2
QC1.1
Screening sol.
Cryostat “walls” thickness.
QC1.1
Outer SS wall 10 mm
Remote flange
10 mm vacuumn
HOM Absorber
Thermal shield 3 mm
10 mm vacuum
LumiCal
Inner wall 6 mm
Correct. sol.(4)
In total: ~40…45 mm
Anti-sol.
Cooling
Anti sol.
Two bellows
BPM
Connection Be-Cu
Workshop, May 2018, Rome
Compens. colls

5. 3D views QC2.1 QC1.3 Top view Side view QC2 Cryostat QC1 Cryostat
BINP
Top view
QC1.1
Anti-sol
HOM abs
Flange
Side view
BPM
LumiCal
Transition 30 mm  40 mm
Flanges
QC2.1
QC1.3
QC2 Cryostat
QC1 Cryostat
Bellows
BPMs
BPMs
Workshop, May 2018, Rome

6. Conceptual design of beam pipe inside cryogenic magnets
Inner stainless steel tube, 0.7 mm thickness with inner Cu coating
Gap 0.7 mm with water flow and wire spacers
Stainless steel tube 0.7 mm thickness with outer Ag coating
Vacuum gap 0.9 mm with Ultem spacers
Outer stainless tube, thickness 1 mm, T=4.2K
Correction coil
If ID=30 mm, the OD is 38 mm
Maximum power load on vacuum beam pipe with ID=30mm due to resistivity losses (assuming Cu) and HOM absorption is 50….100 W/m. Therefore the pipe needs an active cooling. Here we are considering multilayer beam pipe with water cooling:
Workshop, May 2018, Rome

7. Design of 3 layers vacuum chamber.
Ultem ball
(0.9 mm)
Stainless wireless
(0.7 mm)
Chamber (1 mm)
Chambers
(0.7 mm)
In half a year we plan to produce a prototype of the 3-layers vacuum tube. We plan to test the cooling water capacity with LHe temperature out of the prototype and the heater (imitating the beam) inside the camber.
Workshop, May 2018, Rome

8. Stand for testing the vacuum chamber.
Cryocooler SRDK-415
liquid cooling
3 layers Vacuum Chamber
Vacuum
Water
100W
4.5K
Shield 80K
Cryostat
liquid cooling
Now we are preparing a stand for testing the 3 layers vacuum chamber with a length of 1 m.
Workshop, May 2018, Rome

9. BINP Remote flange prototype
Flange outer dimensions for two beam pipes:
Flange 2*radius(2*43)+ distance between beams
At s=1385 mm
Flange outer size
Receiving part
1385* ≈ 128 mm
Incoming part with mechanics
128+6≈134 mm
Length 64 mm 43
Workshop, May 2018, Rome

10. BINP Remote flange prototype
P=100…200 bar.
Gasket (Al)
Rotatable Ring
We designed the prototype of remote flange and after the manufacture we will test the flange connection.
Workshop, May 2018, Rome

11. BINP Remote flange prototype
Workshop, May 2018, Rome

12. Summary
We have started a realistic design of the FCC-ee final focus area which, we believe, satisfies all the requirements both from the detector and accelerator sides. We plan to proceed with development and design of the most critical parts including
(1)    The IR vacuum system,
(2)    The remotely connecting flange,
(3)    The anti-solenoid with individual correctors,
(4)    The first FF quadrupole.
Production of the prototypes is highly desirable.
Workshop, May 2018, Rome

13. Thanks for your attention
Workshop, May 2018, Rome