1. IR Summary M. Sullivan For
M. Boscolo, K. Bertsche, E. Paoloni, S. Bettoni,
P. Raimondi, M. Biagini, P. Vobly, I. Okunev,
A. Novokhatski, S. Weathersby, et al.
SuperB General Meeting XIV
INFN Frascati, Italy
September 27- October 1, 2010

2. Outline Current IR design QD0 Vibration budget and control
Detector solenoid compensation
Layer 0 of SVT and the beam pipe
Polarimetry
Summary

3. Present Parameters (V12 lattice)

4. Parameters used in the IR designs
Parameter HER LER
Energy (GeV)
Current (A)
Beta X* (mm
Beta Y* (mm
Emittance X (nm-rad)
Emittance Y (pm-rad)
Sigma X (m)
Sigma Y (nm)
Crossing angle (mrad) +/- 30

5. Present new designs We have constructed two new designs
Vanadium Permendur “Russian”
Air Core windings “Italian”
The shared PM slices have been removed and the crossing angle reduced to 60 mrad
The other new PM slices are left in the design
We maintain 5 mm of space between the cold mass and the warm bore beam pipe

6. Vanadium Permendur Design
We allow for 3 mm of space for the coils (new information from Ivan – actually 2.6 mm)
The central steel section can be very thin because the magnetic field in the steel has been nearly cancelled from the twin windings
The QD0 magnet is aligned as much as possible to the beam axis, however we must slant it somewhat in order to accommodate the increasing horizontal size of the beam-stay-clear

7. Vanadium Permendur “Russian” Design

11. Air-Core “Italian” Design
We replace the shared QD0 and QF1 parts of the VP design with the air-core design
Also place QD0 and QF1 parallel to the detector axis
Then we have the same field strengths and the LER and HER pieces are the same strength as the VP design

12. Air core “Italian” QD0, QF1

16. VP SR photon hits/bunch (>10 keV)
LER
HER
6.1E6
6.4E5
2.0E4
2.7E5
7.1E7
2.2E6
1.4E6
1.2E4

17. Hits/bunch on the detector beam pipe (VP)
LER
HER
165 17
0.5 30
135 4 39 6
1% reflection rate

18. AC SR photon hits/bunch (>10 keV)
LER
HER
6.4E6
5.1E5
2.2E4
7.7E5
6.8E6
1.1E7
1.7E6
8.4E4

19. Hits/bunch on the detector beam pipe (AC)
LER
HER
173 14
0.6 85 13 21 46 36
1% reflection rate

20. SR power (VP design) 56
115
295 52 8
390 32 42 17
205

21. SR power (AC design) 57
115
311 57 8
402 35 43 17
215

22. QD0
A good deal of work has gone into the “Italian” design (see Eugenio’s talks)
An investigation has been started on a design that has a tapered structure
This would allow for a stronger initial magnet that then enlarges to accommodate the larger BSC near the back

23. Conical shaped QD0

24. QD0 wiring mandrel
Courtesy of Sandro Tomassini

25. Panofsky QD0
Ivan Okunev from BINP gave us a presentation on the IR design of the C-tau factory proposal
The IP has many similarities
+/- 30 mrad xing angle
Dual quad design for the final focus magnets
Compensating solenoids
They are getting ready to build a prototype QD0 style magnet

26. Layout of the C-tau IR
From Ivan’s talk

27. Dual quad design From Ivan’s talk Calculation of magnetic field
QD0 calculations in MERMAID
Harmonics of QD0for different gradients at R = 1 cm
N an an an
E E E-05
•All 2D and 3D calculations were made by MERMAID
•There is no yoke saturation at 11 kG/cm (vanadium permendur)
•There are still no requirements on harmonic content
•3D calculations give ΔG/G ±10-3without chamfers
•Chamfers are not optimized

28. 3D model
From Ivan’s talk
The beam pipe is at liquid N2 temperature

29. More 3D model
From Ivan’s talk

30. Vibration control for the FF
Kirk Bertsche had a presentation on estimating the effect of measured ground motion on the final focus magnets
This is a preliminary analysis and will be further refined

31. Measured vibrations
From Kirk’s talk
Measured by the Annecy group

32. Simple model of measurement
From Kirk’s talk
This is the expected motion of the beam from the ground motion

33. Resulting beam motion at the IP
Using a 100 Hz bandwidth fast lumi feedback system with a 30x reduction of beam motion
From Kirk’s talk
8 nm of beam motion results in a 1% luminosity loss

34. Detector Solenoid compensation
Yuri Nosochkov has produced an IR lattice that includes the detector solenoid
The model assumes that the compensating solenoids in the cryostats zero out the detector field everywhere except +/ m from the IP (as proposed by Sullivan/Bertsche)
This is a lot of complicated work and hence does not get done until the lattice is somewhat stable
Yuri has done a first order linear correction and as things become more stable a more sophisticated model and correction scheme can be developed that includes the non-linear terms

35. Solenoid model
HER
LER
We have a 1.5T field from the detector only between the cryostats

36. Linear effects on the beams
Detector solenoid creates the following linear effects on the beam:
Coupling of X & Y betatron motion (rotation around S-axis).
Vertical orbit due to the solenoid horizontal angle with respect to the beam.
Horizontal orbit induced by vertical orbit and coupling.
Vertical and horizontal dispersion due to the Y and X orbit bending.
Perturbation of Twiss functions due to weak focusing in X & Y planes.
From Yuri’s talk

37. Correction system From Yuri’s talk
The designed correction system compensates each half-IR independently and contains on each side of IP:
Rotated permanent quads.
Skew winding on SC quads to simulate rotation.
SC anti-solenoid of strength 1.5T x 0.55 m aligned with the beam axis.
2 vertical and 2 horizontal dipole correctors for orbit correction.
4 skew quads at non-dispersive locations for coupling correction.
2 skew quads at dispersive locations for correction of vertical dispersion and slope.
The nominal FF quads are used to rematch the Twiss functions and horizontal dispersion.
Solen
QS1 V1 H1 H2 V2
Anti-
solen
Other correctors are outside of this region

38. Central beam pipe and L0
Filippo Bosi has been working on the central beam pipe and Layer 0
He has a new layout that fits inside the requirements of the SR and beam-stay-clear near the IP (not quite – but close enough)

39. MAPS L0 module Design
HDI is positioned on outer radius for better radiation damage conditions
Al-kapton BUS
HDI
Z-piece
MAPS chips
Input coolant
Microtube support
From Filippo’s talk
Necessary thermal-structural simulation to verify L0 module mechanical stability
Output coolant

40. Beam Pipe
In order to resume: The beampipe consists of two Be cylinders with a layer of cooling water in beetwen. The inner cylinder is the beam pipe and the outer is the water jacket (Babar Style). The outer surface of the beam pipe must be machined in order to obtain a microchannels structure.
to protect from water corrosion the outer surface of beam pipe and the inner surface of water jacket must be nickel-plated (7÷10 mm). The oxidation of the outer surface of water jacket must be prevent using a corrosion inhibiting primer (~15 mm). Gold must have to be sputtered onto the inside surface of the beam pipe (3÷6 mm).
From Filippo’s talk

41. Beam Pipe with L0 From Filippo’s talk
Bellow positioned downstream C.F. flanges mantaining same pipe length respect previos design

42. Internal Bellows From Filippo’s talk NW25CF Flange Bellow
Beam pipe manifold
L0 Modules manifold

43. Polarimetry Ken Moffeit gave us an update on the polarimeter
It occurred to us at the last meeting that it would be nice to be able to measure the transverse polarization as well as the longitudinal polarization
We could measure the spin depolarization resonances which would give us a good calibration of the LER beam energy – something we never had in PEP-II
Ken pointed out that a modification to the gamma detector of the present polarimeter could give us the transverse polarization (assuming we turn off the spin rotators)
The gamma detector would have to be significantly more complex but this is clearly cheaper than another polarimeter

44. Right and left handed laser light difference for vertical spin electrons
From Ken’s talk

45. From Ken’s talk

46. From Ken’s talk

47. Summary
We have found that increasing the crossing angle makes it more and more difficult to satisfy the SR background requirements
We have reset the crossing angle back to 60 mrads
This removes some of the space for the PM slices as well as the dual quad super-conducting magnets
Presently the dimensions of these elements are “snug” but acceptable at this stage (actual engineering requirements will no doubt alter the design again)
We have two designs that work for SR backgrounds
Vanadium Permendur (with Holmium as an option)
Parallel air-core dual quads + vanadium permendur Panofsky quads on the HER

48. Summary (2) These two designs demonstrate initial robustness
Two separate QD0 designs work
The direction of the beams can be either way with a current preference for the incoming beams to be from the outside rings due to the location of the SR power on the cryostat beam pipe
These new designs greatly improve the lattice and energy flexibility of the overall IR design

49. Summary (3) Good progress is being made on the design of the QD0
The engineering details for the “Italian” design are being studied
A prototype Panofsky style QD0 is planned for the BINP C-tau design
An overall vibration control design is being developed for the FF magnets
We have a first look at correcting the effects of the detector solenoid in hand
The polarimeter design is being studied to enable measuring transverse polarization

50. Conclusions
We have two designs that satisfy our first order SR requirements
The IR design is looking better, is converging and is maintaining flexibility
Engineering details are starting to be hammered out