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, R. Centi, A. Perez, et al.
SuperB General Meeting XV
Caltech, Pasadena, CA
December 13-17, 2010

2. Outline Current IR design + SR backgrounds QD0
Detector solenoid compensation
Vibration budget and control
HOM
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. 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

6. Vanadium Permendur “Russian” Design

7. 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

8. Air core “Italian” QD0, QF1

9. SYNC_BKG Originally QSRAD (by Al Clark of LBL) Enhancements
Histograms the critical energies of the SR fans
Very fast – A setup with as many as 60 masks, 30 magnets and a 20 by 45 beam scan in 0.1 steps takes seconds to run on a 7 yr old laptop
This allows for rapid masking design changes or for various beam particle profile runs
Enhancements
Second gaussian beam tail distribution
Offsets and tilts to magnets (Stan Hertzbach of UMass)
Parametrization of the energy spectrum
Series of falling exponentials over the energy range
This function is easily transferred over to the EGS4 program for efficient photon generation

10. Masking
EGS4 interface program to track photons that strike a beam pipe surface using input from SYNC_BKG
Fast – 108 photons takes about 2.5 min. on a 7 yr. old laptop – present code limit is 2x109 photons for a single run (run results can be added)
Some features
Several photon energy spectra options
Twenty different materials with 10 layers possible
Reflection / transmission / absorption
Any angle of incidence to surface
Surface can have an edge
Surface can have a radial tip
Reflected photons can be tracked for possible hit on the inside of a cylinder surface (detector beam pipe)
Reflected (or transmitted) photons can be saved as input to another MASKING run (photon files can be added together)

11. VP SR photon hits/bunch (>4 keV)
From SYNC_BKG
LER
HER
8.1E6
2.5E6
7.1E4
6.5E5
1.1E8
5.4E7
3.8E6
3.0E4
SB_SF10A_7_A.LIS
SB_SF10A_4_A.LIS

12. Hits/bunch incident on and through (n) the detector beam pipe from the HER
Using a conservative beam tail
LER
HER 47
(12) 51
(4.2)
201
(2.6)
113
(6.3)
Beam pipe has 3 m Au
SB_SF10A_7_A series

13. SR power that strikes beam pipe inside the cryostats
We can now model the SR power that strikes the beam pipe inside the cryostats and find how much power penetrates the pipe
The most difficult part to control is the section of beam pipe inside the QD0
We may find that we will need to coat the inside of the beam pipe with Au or some other high Z material in order to increase the x-ray absorption

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

15. First few runs looking at the QD0 beam pipe
Tried three cases
Incident power is 210 W
Attenuation
1 mm Cu x10-2
Power through beam pipe (W)
10um Au and 1 mm Cu 1.4x10-2
Power through (W)
1 mm Au x10-5
Power through (W)

16. SR background summary
We can rapidly model various designs and find the best design parameters that minimize the backgrounds from SR
We have found (no surprise) that the photons that hit the closest to the detector beam pipe have the highest probability of making background in the SVT
We have also found that a 1 mm Cu beam pipe inside the cryostat is not enough to shield the cold mass from the x-ray fans of the upstream magnets
Some form of high Z material beam pipe is necessary (10 m of Au is not enough)

17. QD0 Work is continuing toward building a prototype QD0 magnet
Eugenio showed current progress
We have acquired some of the CMS wire for this proto-type
The wire is bare and needs to be insulated

18. E. Paoloni

19. E. Paoloni

20. Study of the higher order multipoles
E. Paoloni

21. QD0 Summary
E. Paoloni

22. Detector Solenoid compensation
At the last workshop Yuri Nosochkov produced an IR lattice that includes detector solenoid compensation
In this workshop he showed how to run the machine with the detector solenoid off. This is an important option and one of the driving reasons to do this is to get a better understanding of the solenoid compensation scheme.
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)
Anti-solenoids are included in the correction scheme as well as a series of skew quads and correctors, but the alterations of the final focus magnets to introduce skew terms into these magnets make the solenoid off scheme more interesting as some of these adjustments remain even when the solenoid is turned off.

23. Solenoid off scheme
For instance, the solenoid on scheme adds skew terms to the PM quads as well as to the SC QD0 magnets
The skew terms added to the SC QD0 may not be removable when the detector solenoid is turned off and Yuri assumed this was the case
Yuri studied two cases, one where the skew term in the PM slices was left untouched and another where the skew term in the PM slices could be adjusted (rotation).

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

25. Solenoid corrector locations
Y. Nosochkov
Detector
solenoid
QS1 V1 H1 H2 V2
Anti-
solen
QD0
LER
HER
Correctors within ±7.5 m of IP (symmetric relative to IP)
QF1 IP
QD0P
QS1
QS3
QS2
QSDY
QS4
QSDPY
Skew quads in one half-IR
QS1,QS2,QS3,QS4 – at zero dispersion
QSDY,QSDPY – at non-zero dispersion
[bxby]1/2
CCX
CCY
ROT IP

26. LER corrector strengths
Solenoid ON
Solenoid OFF option 1
Solenoid OFF option 2
Left
Right
QD0P
Angle (rad)
1.80e-2
-1.80e-2
-6.97e-2
6.97e-2
QS1
K1 (m-2)
-3.83e-3
-7.98e-3
-2.37e-2
2.38e-2
-1.13e-1
1.13e-1
QS2
-1.22e-3
-1.94e-3
-1.72e-2
1.69e-2
4.47e-3
-4.47e-3
QS3
-3.27e-3
-4.92e-3
6.28e-2
-6.72e-2
-1.41e-4
1.50e-4
QS4
2.73e-3
4.01e-3
-5.08e-2
5.15e-2
-4.67e-4
4.74e-4
weak
Solenoid OFF, option 1
QS1,QS2,QS3,QS4 strengths are increased compared to solenoid ON.
Solenoid OFF, option 2
QD0P angle is adjusted by a factor of for more local correction.
Most of the correction is done by stronger QS1 quad.
Strengths of QS3, QS4 are very low.
Y. Nosochkov

27. HER corrector strengths
Solenoid ON
Solenoid OFF option 1
Solenoid OFF option 2
Left
Right
QD0P
Angle (rad)
1.46e-2
-1.46e-2
-1.37e-2
1.37e-2
QS1
K1 (m-2)
4.61e-3
2.80e-3
-1.52e-2
1.52e-2
-7.11e-2
7.10e-2
QS2
8.55e-4
5.60e-4
-1.35e-2
1.35e-2
-2.12e-3
2.12e-3
QS3
9.20e-4
6.73e-4
1.05e-2
-1.04e-2
6.76e-6
-9.35e-6
QS4
-3.53e-4
-2.75e-4
-3.49e-3
3.14e-3
9.34e-5
-9.21e-5
weak
Solenoid OFF, option 1
QS1,QS2,QS3,QS4 strengths are increased compared to solenoid ON.
Solenoid OFF, option 2
QD0P angle is adjusted by a factor of for more local correction.
Most of the correction is done by stronger QS1 quad.
Strengths of QS3, QS4 are almost canceled.
Y. Nosochkov

28. Solenoid off summary
The IR lattice v.12 with SC QD0, QF1 quads was used.
It was assumed that the skew quad coil strength in the SC QD0, QF1 quads cannot be turned off or changed when the solenoid is OFF.
It was assumed that the rotation angle in the permanent quad QD0P can be adjusted.
It is shown that when the detector solenoid is OFF and the bucking solenoids and anti-solenoid are OFF, the correction of QD0P and QD0, QF1 coupling can be done using the included QS1,QS2,QS3,QS4 skew quads.
The solenoid OFF coupling correction is most efficient and localized when the rotation angle in the QD0P permanent quad is optimized.
Y. Nosochkov

29. Vibration Control for the FF and Further Measurements of the Frascati Site Ground Motion
We had two very nice presentations on vibration control and measurements
Kirk Bertsche showed further analysis of the FF vibrations
Laurent Brunetti showed new data on ground motion measurements at Frascati as well as some considerations on controlling the ground motion

30. Summary of the 1st campaign
Vertical ground motion measurements during 18 hours
[0.2; 1]Hz: vary from 65nm to 76nm  low compared to many other sites in the world (Desy team study) but may be higher in a longer time
[1; 100]Hz: vary from 12 to 65nm (quite low) except from 8h to 9h40
Max (transient): 700 nm
Max (average): 240 nm
→ Due to traffic observed in the range [3; 30]Hz, it increases up to : - 240nm (Average of 20’) nm (Transient of 6s)
GM measured simultaneously on surface and in a 50m depth hole
Cultural noise well attenuated in depth on its entire frequency range
→huge vibrations due to traffic should be well attenuated in depth
L. Brunetti
Very better if Super B is in underground !!
CalTech - SuperB 2010 30

31. 2nd campaign : objectives
To repeat and to increase the quantity of data
L. Brunetti
Short term measurement at different points
Long term measurement
Comparison of underground and surface measurement in the news holes
Coherence measurement in function of the concrete and of the location : Daɸne experiment 1 5 4 3 2
CalTech - SuperB 2010 31

32. Summary of the 2nd campaign
GM measured simultaneously on surface (various vibrations sources) and in different depth holes
Cultural noise well attenuated in depth on its entire frequency range.
Difficulties to correlate the attenuation between the different points with short term measurements.
The damping is function of the cultural noise level.
Horizontal GM not much higher than vertical GM compared to tolerances.
Coherence for different distances at 2 pts in the Daɸne
The type of the concrete is very important (comparision basement and Daɸne)
Daɸne QDO motion and experiment influence
The structure is quite rigid even if it was not made for vibrations
The influence of the process can be very important
A lot of datas which are very important for the stabilization strategy
It still some analysis but LNF seems to be a good site for vibrations
Other sites comparison (Tor Vergata, LHC, Desy data…)
L. Brunetti
→ a INFN report is under progress.
CalTech - SuperB 2010 32

33. Stabilization L. Brunetti
Link between the measurement and the strategy of stabilization (final focus)
The target is to have a differential motion between the 2 beams lower than the tolerances
The approach will be selected in function of :
The specifications
The distance between the 2 last QD0
The coherence of the ground motion
The level of the ground motion
The mechanical properties of the QD0 et its support
The influence of the internal system
The beam repetition rate …
The simulation of the whole system can be started thanks to the measurements.
Ex of applications : ATF2 and the current developments dedicated to CLIC
L. Brunetti
CalTech - SuperB 2010 33

34. Summary of our activities dedicated to the control part
L. Brunetti
Methodology of the stabilization of the future Compact Linear Collider
- Dedicated instrumentation (Sensors, actuators, filters, acquisition system etc…)
- Association of controls : active / passive isolation, active compensation, beam trajectory
control
- Feasibility demonstration of the beam stabilization and active compensation
- New specification of the active/passive isolation
Current activities :
Implementation of the control of the home made mechanical isolation and tests
Implementation of the beam control strategy in a beam accelerator simulation (PLACET) and test on a prototype.
Future prospects :
The limitation is the sensor : future study in order to use the mass of the magnet 34
CalTech - SuperB 2010

35. Vibration control for the FF
Kirk Bertsche extended his analysis of the vibration issues for the final focus magnets and what we need to achieve in motion control to keep the beams in collision
The primary improvement is finding out that the two beams tend to move together when the QD0 moves because the twin QD0’s on one side are one mechanical piece

41. Summary Must keep quad motion below 1 μm
Cantilevered cryostat should be designed for low vibration
Damp resonances and push > 10 Hz
Support cryostat on both sides of detector door
Must keep cryostat rotation below 2 μrad
Avoid building torques into magnet supports
Beam feedback should extend to > 100Hz, provide > 10x vibration reduction at LF
But we may not even need beam feedback during quiet parts of day
Vibration should not be a problem for SuperB at LNF, even at rush hour

42. IR HOM studies
Stephen Weathersby presented further progress on the issue of HOM power deposited in the IR
He has concentrated on the 1 m section around the IP
The first approximation used square beam pipe chambers

43. First model of the IR for HOM and wake-field studies
First model of IR with square chambers

44. New model
Stephen has studied how to use parallel processors and super-computers to produce and run a newer round chamber model
Introduce SLAC Advanced Computing Department parallel Finite Element Method electromagnetic time domain solver (t3p) as a tool for IR wakefield computation.
Compare with gdfidl finite integration techniques (MAFIA)
Consider simple intersecting tubes as a generic model for an IP
S. Weathersby

45. mesh radius 10 mm angle 66 mR length 1 m conformal vs staircase
S. Weathersby
radius 10 mm
angle 66 mR
length 1 m
conformal vs staircase
loss factor vs mesh size
8mm bunch length
gdfidl
cubit

46. Beam’s eye view
S. Weathersby

47. HOM Summary
S. Weathersby
loss factor for round tubes is small compared to model of the Super B IR
Convergence is slightly better with t3p for this study
More exhaustive study needed

48. Summary We have two designs that are flexible and have good:
SR backgrounds
Lattice functions
Beam apertures
The two designs are:
Vanadium Permendur for QD0 and QF1
Parallel air-core dual quads for QD0 and QF1
Both designs include additional vanadium permendur Panofsky quads on the HER

49. Summary (2) These IR design demonstrates initial robustness
Two separate QD0 designs work
The direction of the beams can be either way with a weak 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 designs greatly improve the lattice and energy flexibility of the overall IR design

50. Summary (3) Good progress is being made on the design of the QD0
A prototype of the air-core design is being built
An overall vibration control design is being developed for the FF magnets. The added measurements of the Frascati site are very encouraging and the fact that the beams tend to move together with QD0 motion has significantly loosened the tolerance requirements on cryostat motion

51. Summary (4)
We have a scheme for correcting the effects of the detector solenoid and now we know what we need to do to run the machine without the detector solenoid
HOM analysis is improving and will soon be ready for details concerning the beam pipe

52. Conclusions The IR design is converging and is maintaining flexibility
Engineering details are starting to be hammered out
As engineering concerns are uncovered we will have to make modifications to the design but this design has the room and robustness to respond to these demands