1. Relaxing Quads Roll Alignment tolerance
Arun Saini, N. Solyak
(19th August 2015)

2. Alignment tolerances (LCLS-II requirements)
Nominal RMS alignment tolerances in cryomodules.

3. Cryomodule Magnet Integration, Magnet Review, 16 April 2015
Invar Rod
BPM BP Spool Quad DS Gate Valve
Connection to invar rod
Cryomodule Magnet Integration, Magnet Review, 16 April 2015

4. Initial Position in Clean Room (BPM+ Spool were assembled on a bench).

5. All parts are aligned and connected

6. Magnet Assembly :Preparation to magnet installation outside clean room (1)

7. Magnet Assembly :Preparation to magnet installation outside clean room (2)

8. Magnet Assembly :Preparation to magnet installation outside clean room (3)

9. Presenter | Presentation Title
Mechanical tolerances for pin locations
Θ=3mrad ~ 0.2°
R =50mm
Δs =50mm x 3mrad = 150µm
6mrad  0.3mm
A rough estimation shows that 3 mrad roll requires pin–holes accuracy of 150µm.
BPMs assembly received from DESY have pin offset of ~ mm.
11/23/2018
Presenter | Presentation Title

10. Quad Roll Errors z
All other nominal errors are applied and Quad Roll error is varied to understand its implication on emittance growth.
Analysis is performed for L3 section. 50 Machines are used.
Mean emittance and 90% emittance is plotted.

11. Twiss parameters along L3 section
Beam is round and phase advance and emittance in both horizontal and vertical planes are similar.
T = ex/kx = ey/ky results in no coupling between planes.

12. Quad Tilt Errors Dy z
All Nominal Errors are applied and Quad Tilt error is varied to understand its implication on emittance growth.
Analysis is performed for L3 section. 100 Machines are used.
Mean emittance and 90% emittance is plotted.

13. Conclusion
There is no significant increase in mean emittance growth and 90 % emittance growth even after relaxing quad rolls errors from 3000 mrad (nominal) to mrad.
Relaxing quad tilt error shows increase in 90 % emittance growth. There is less than 10 % emittance growth if quad tilt error is increased from nominal (3000 m rad) to m rad.
No correction algorithm is applied.
In final conclusion, it is possible to relax quad roll alignment tolerances. However, relaxing quad tilt may result in accountable emittance growth.