PS Ions for LHC (PIL)
Overview
Preparation of the PS machines as ion injectors for the LHC
Status and planning
Dieter Möhl
11
PS ions for LHC PS days, Jan 2001
Facets
Development of an improved ECR-source (PP Group & collaboration)
Alternative:Laser Ion Source ( PP Groupoutside collaboration )
Improvement of Linac III ( PP Group )
LEIR project ( AE Group,)
Adaptation of PS ring ( injection, vacuum, RF ...) (AE, PO, RF... -Groups )
Stripping insertion in TT2 (AE Group )
Intensity target figures (LHC-limits ) (cf.: D. Brandt)
ION / LHC ions/bunch / limit / over-all efficiency taken / PS ions/bunchPb(82) / 6.8 E7 / quench / 0.3 / 2.3 E8
In(49) / 2.8 E8 / quench / 0.4 / 7.0 E8
Kr (36) / 5.5 E8 / IBS 10h / 0.5 / 1.1 E9
Ar (18) / 2.2 E9 / IBS 10h / 0.6 / 3.6 E9
O(8) / 1.2 E10 / IBS 10h / 0.7 / 1.7 E10
He(2) or d / 2.0 E10? / detector / 0.8 / 2.5 E10?
p / 1.05 E11 / beam-beam / 0.95 / 1.1E11
Hierachy of Requests.
1.lead on lead ( "Pb on Pb") year >=2006
2.lighter- on lighter ions ( "A on A") year >=2008
3.ions on protons ( "A on p" ) year >=2009
4.ions on deuterons or better Helium
( "A on d or e" ) year >=2009?
5. heavy ions on light ions ("A on B" ) year >= ???
The deuteron (and ion A on ion B) story
- Linac III cannot (easily) accelerate deuterons (Q/A=1/2)
- Linac II can accelerate deuterons (2 mode) but needs shut-down (1 or several days) to exchange sources. No protons during deuteron operation (and vice versa).
- Linac III can accelerate He1+ (Q/A = 1/4). Sources +RFQ-s on "switch yards" make possible fast switch over (few min.) between two sources (two ions).
Recommend:Two branch switch yard for "ion A on B"
He(2) instead of d as lightest ion (apart from p)
Emittance budget
( normalised transverse emittanc, 1 )
Machine
(at top energy)
/ions ( lead)
*=m
/protons
*=m
LHC
/1.5
/3.75
SPS
/1.2
/3.5
PS
/1.0
/3..0
LEIR
/0.7
/-----
SomeChallenges
Generation/Conservation of the high beam densities
Space Charge Limits, esp. for intensities required for lighter ion beams
Vacuum ( pressure increase induced by ion beam losses)
Stacking/Cooling schemes for the different kind of ions
Time scale, human and financial resources ....
PS
Injection from LEIR at "highest energy possible"for lighter ions (B= 2.2 .... 4.5 Tm, TPb = 14.8 ... 64.4 GeV/u , proton eq. 200 ....700 MeV) B > 2.2 Tm requires new septum and kicker in PS
Acceleration on h=32 to intermediate energy (T~260 MeV/u), stepwise change to h -->17. Acceleration to 4.25 GeV/u ( 18 GeV proton eq. ). Bunch compression and ejection towards SPS Needs Rf-gymnastics but (hopefully) existing RF ( 2.7 - 9.5 Mhz 180 KV) can be used
Stripping (Pb54+ --> Pb82+) in TT2 . Needs stripping insertion (low beta) to limit emittance blow up.
PS space-charge limit (4bunch mode)
ION / ion ch.state / "required"
PS ions/bunch / space-charge
limit in PS
ions/bunch / ratio:
obtainable/ required / bunch length
[m]
Pb(82) / 54+ / 2.3E8 / 4E8 / 1.7 / ~9
In(49) / 37+ / 7.0E8 / 4.5E8 / 0.6 / ~8
Kr (36) / 29+ / 1.1E9 / 5.5E8 / 0.5 / ~8
Ar (18) / 16+ / 3.6E9 / 8.6E8 / 0.25 / ~8
O(8) / 8+ / 1.7E10 / 1.4E9 / 0.08 / ~8
He or (d) / 2.5E10? / 5.5E9 / 0.2 ? / ~8
Assumptions: Q=0.25, equally spaced bunches, 120 ns gap for kicker gap, transfer LEIR-PS at B <= 4.5 Tm (1.4 GeV/c proton equiv.) , charge state as obtained (optimum) for stripping at 4.2MeV/u (after Linac III)
How to boost PS-space charge limit
ION / ion ch.state / "required"
PS ions/bunch / space-charge
limit
ions/bunch / bunch mode / bunch length / filling time/ring
(min)
Pb(82) / 54+ / 2.3E8 / 4.0 E8 / 4 / 9 / 10
In(49) / 37+ / 7.0E8 / 9.0 E8 / 3 / 13 / 15
Kr (36) / 29+ / 1.1E9 / 1.1 E9 / 3 / 13 / 15
Ar (18) / 16+ / 3.6E9 / 3.8 E9 / 2 / 24 / 20
O(8) / 8+ / 1.7E10 / 2.1 E10 / 1 / 61 / 40
He or (d) / 2.5E10? / 8.3 E10 / 1 / 61 / 40
Assumptions: as in previous table , transfer exactly at B = 4.5 Tm (1.4 MV/c proton equivivalent) .
11
PS ions for LHC PS days, Jan 2001
11
PS ions for LHC PS days, Jan 2001
STATUS and CONCLUSIONS
Lead scheme fully determined , all technical systems under specs. optimised for lead, keeping door open for lighter ions
Table and scheme for ( max 5 ) lighter ions established. Final intensities need re-discussion with LHC and SPS.
Planning (calling for first Pb-Pb coll. end 2006) worked out
Working group (esp. on PS-problems) called up
Design report before end 2001, LEIR report before .
Vacuum ( pressure increase induced by ion beam losses), Stacking/Cooling schemes for the different kind of ions and Space-charge limits ... are (some) remaining challenges
11
PS ions for LHC PS days, Jan 2001