1. PS2 Injection/Extraction Layout
Wolfgang Bartmann
PS2 Meeting, 23-May 07

2. PS2 Meeting: Inj/Extr Layout
Outline
Aims
Optics in LSS
Space Requirements – Injection
H--Injection – Lorentz stripping and Septum geometry
Space Requirements – Extraction/Beam dump
Conclusion of space requirements
Fitting Injection/Extraction together
Next steps
23-May 07
PS2 Meeting: Inj/Extr Layout

3. PS2 Meeting: Inj/Extr Layout
Aims
Injection:
Fast Injection
H--Injection
Extraction:
Fast Extraction
Resonant Extraction
Low-loss 5 turn continuous transfer
Beam dump (assumed internal)
23-May 07
PS2 Meeting: Inj/Extr Layout

4. PS2 Meeting: Inj/Extr Layout
FODO Lattice - LSS
Betafunctions and Dispersion in the LSS:
betx, bety < 42 m
Dx < 10 cm
23-May 07
PS2 Meeting: Inj/Extr Layout

5. Space Requirements: Injection (1)
Fast Inj. needs one cell. We see no special issues with this system.
H--Inj. is limited due to Lorentz Stripping:
For energies up to 3.5 GeV, the field strength in dipoles must not exceed 0.14 T (2.4 · loss/m) which corresponds to a maximum deflection of ~ 9 mrad/m;
Field at 75 mm offset in quadrupoles does not exceed these limits (at injection energies!).
23-May 07
PS2 Meeting: Inj/Extr Layout

6. H- -Inj: Lorentz stripping…
Can parameterize formula for lifetime in magnetic field
t = a/E x exp(b/E)
Where t = lifetime, a~4x10−14 s-MV/cm, b~44 MV/cm and E is Lorentz-transform of the magnetic field B (E [MV/cm] = 3.20 p [GeV/c] x B [T]).
Rule of thumb : p x B ≤ GeV/c x T
More exactly: for PS2 injection at 4.8 GeV/c (4 GeV kinetic) should keep fields below T (corresponds to about 10-3 loss per m of field)…gain x10 in loss at fixed B at 3.5 GeV!
23-May 07
PS2 Meeting: Inj/Extr Layout

7. H--Inj: Lorentz Stripping – total losses
Need to aim for 10-3 total loss
Few 10-4 per element/system
Bend angles were assumed at 200 mrad…
Maximum bend about 9 mrad/m (3.5 GeV)
Would need ~20 m of injection septum!!!!
In one FODO ½ cell have ~ 10 m free drift
Assume 8 m magnetic length for septum
Maximum deflection is then ~ 70 mrad.
23-May 07
PS2 Meeting: Inj/Extr Layout

8. Space Requirements: Injection (2)
H--Inj. in FODO structure:
Injecting in one halfcell (~11.3 m free drift) with several septa reaches a displacement of about 0.57 m at the quadrupole.
Going through the coil window of the enlarged quadrupole avoids large septum kicks but needs one halfcell more.
H--Inj. occupies 1.5 to 2 cells
Space requirement for injection: 2.5 to 3 cells
23-May 07
PS2 Meeting: Inj/Extr Layout

9. H--Inj: Injection septum geometry
570 mm
60 mm
2.0 m, 18.0 mrad
Difficult (but maybe not impossible!) to get past upstream
quad yoke and into the downstream quad aperture.
23-May 07
PS2 Meeting: Inj/Extr Layout

10. H--Inj: Injection septum geometry ‘coil window’ alternative
300 mm
60 mm
2.0 m, 7.5 mrad
Less bending angle, but the first meters of the halfcell before are needed, too.
23-May 07
PS2 Meeting: Inj/Extr Layout

11. Space Requirements: Extraction
the three extraction systems need 4.5 cells according to the conceptual design (Jan 07)
rearrangement of the elements in the extraction and placing the extraction kicker in the dispersion suppressor gives a requirement of three cells in the LSS
Problems:
larger apertures in the dipoles
less flexibility in the design of the dispersion suppressor S S
23-May 07
PS2 Meeting: Inj/Extr Layout

12. Space requirements: Beam dump
Vertical plane…
Internal dump block
at about 40 mm aperture
Dump kickers filling one half-cell
(~ 2.5 mrad needed at 50 GeV)
Vertical has some advantages:
- smaller beam size at injection means block closer to orbit  lower kick
Needs to fit into long injection/extraction straight section….
- infrastructure, radiation
23-May 07
PS2 Meeting: Inj/Extr Layout

13. Conclusion of space requirements
Injection: 2.5 to 3.0 cells
Extraction: cells (4.0 total)
Dump: cell
Total: 6.5 to 7.0 cells
23-May 07
PS2 Meeting: Inj/Extr Layout

14. Optimum (?) fitting together with present lattice
Fast Injection
H--Injection
Extraction DS
InjK
InjS
H0S
H-InjS
MTEBK
MS2
MS1 ES
MTEBK
ExtK
6 cells
No room for beam dump
Kicker in Dispersion Suppressor
23-May 07
PS2 Meeting: Inj/Extr Layout

15. Options for inj/extr straight without using the DS
Fast Injection
H--Injection
Extraction
Beam Dump
InjK
InjS
H0S
H-InjS
MTEBK
MS2
MS1 ES
MTEBK BD
DuK
ExtK
InjK
InjS
H0S
H-InjS
MTEBK
MS2
MS1
ExtK
MTEBK BD
DuK ES
7 cells
23-May 07
PS2 Meeting: Inj/Extr Layout

16. PS2 Meeting: Inj/Extr Layout
Next steps:
Iterate Inj/Extr Layout Versions
Designing the arc as an achromat saves one cell per arc (cell length is shorter)  7 LSS cells
Use different cell structure in the LSS, e.g. Doublet
Increase dipole strength in the arc in order to gain one cell more for the LSS (7 cells) for same circumference
More detailed H- -injection design!
23-May 07
PS2 Meeting: Inj/Extr Layout