Plans for ions in the injector complex D.Manglunki with the help of I-LHC and LIU-PT teams Special acknowledgements to T.Bohl, C.Carli, E.Carlier, H.Damerau, L.Ducimetière, R.Garoby, S.Gilardoni, S.Hancock, J.Jowett, D.Küchler How can we reach the requested beam parameters for high luminosity operation in I-LHC after LS & LS3?
Previously on the LHC ion injector chain Nominal beam in Design report L = 10 7 cm - s -1 at 7 TeV/c/charge ~600 bunches of 7x10 7 Pb 8+ ions H,V = 1. m H,V * = 0.5m To combat IBS and space charge on SPS flat bottom, Complicated gymnastics in PS & SPS (splitting in bunchlets in PS, recombining in SPS using 100MHz system). Scheme questioned in Chamonix XII (003) Decision to start with EARLY scheme, single bunch from LEIR > PS > SPS Assumed possibility of up to 13 PS injections into SPS
Experience in 010 (EARLY) and 011 Linac3 delivers ~30-40% of design (15-0 A vs 50) Additional injections in LEIR Better beam lifetime at low energy in PS thanks to excellent vacuum IBS and Q on SPS flat bottom less harmful than foreseen EARLY run in 010: 1. 10 8 ions/bunch; H,V = 1. m ; L = 3x10 5 cm - s -1 at 3.5TeV/c/charge Provisionally demonstrated that bunchlets are unnecessary Raised the bar high for 011 run (Terribly named) INTERMEDIATE run in 011 (Beam designed over coffee in Evian) Keep bunch intensity as high as possible (no splitting) Insert as many bunches as possible into LHC quick n dirty, reversible 00 ns bunch spacing in PS Batch spacing 00ns thanks to shorter SPS injection kicker rise time (only 3 modules at 17GeV/c/charge)
Present scheme ( intermediate in 011) LEIR 7 multiturn injections of Linac3 pulse (~15-0 A) bunches of 4.5x10 8 Pb 54+ PS (similar gymnastics as nominal, minus splittings) Batch expansion h = 16 -> >14 -> >1 Rebucketing (was splitting) h = 1 -> 4 Batch expansion h = 4 ->1 Rebucketing h = 1 -> 169 After stripping, bunches of ~3x10 8 Pb 8+ bunch spacing 00 ns SPS 1 injections of PS batches, batch spacing 00 ns 4 bunches of ~1.4x10 8 Pb 8+ (0.9x10 8 design) Transverse emittances ~0.85 m (1. design)
Present issues (which have limited 011 performance to only x design lumi ) Low current from Linac3 Forces LEIR to inject 7 times instead of 4, decreasing cooling time LEIR losses after capture and at the beginning of the ramp Currently not understood Longitudinal emittance budget in PS Not an issue when splitting but creating satellites otherwise RF Noise, IBS & Q on SPS flat bottom First batch suffers 40 more seconds on flat bottom: lower intensity/bunch, transverse emittance blowup
Users requirements 01 p-pb 015-17 Pb-Pb (+ p-pb) 019-1 Pb-Pb, p-pb and Ar-Ar Ar-Ar if and when Pb-Pb accumulated more than 1 nb -1 while ~0.15 nb -1 accumulated in 011 After LS3 Pb-Pb Goal: 10 nb -1 needs ~4-5 luminosity increase Also after LS3 d-pb? ALICE will tell at the end of 01 No other species requested as of now
functions at IP Luminosity increase Note: current brightness performance is already x design Transverse emittances Intensity per bunch Number of bunches -> reduce spacing Nominal was 100 ns / 5 ns Present scheme is 00 ns ALICE ask for 50ns but number of bunches will not be x4 Influence of LHC injection kicker (0.9 s) & abort gap (3 s) Effect of SPS kicker rise time: 1 injections in SPS Scaling Luminosity as N B x I B
Lumi scaling (%) vs SPS injection kicker rise time (ns) 400 350 300 50 00 150 100 50 50ns (double injector perf) 50ns (present injector perf) Present (011) 100ns no splitting (present perf) Nominal (as design) 0 0 50 100 150 00 50
Possible route to 50ns Design current from Linac 3 (~50 A) LEIR Produce bunches of ~10 9 Pb 54+ in same emittance (i.e. twice today) PS gymnastics Batch compression to 100ns h = 16 -> 18 -> 1 (no need for new cavities, 10MHz system exists) Splitting h = 1 -> 4 (0MHz system exists but V RF acceptance to be checked) 4 bunches > 1.4 x10 8 Pb 8+ into SPS 1 SPS injections spaced by 50ns Similar bunch quality as present beam 48 bunches of ~1.4x10 8 Pb 8+ Transverse emittances ~0.85 m But with 50ns spacing and hopefully less spread in bunch population Note: longer LHC injection time
Necessary studies/upgrades Linac 3 (~50 A) New ECR source? Multiple charge acceleration? Faster Linac rep rate (10Hz)? Construction of Linac 5? LEIR loss at acceleration / limits to be understood ECOOL? Transverse damper? PS Tranverse damper? RF gymnastics Revive bunchlets scheme? SPS Can Q0 help on flat bottom? RF noise? Upgrade of MKP? Increase cycle length? Reinstall 100 MHz system (cavities, amplifiers, beam control)?
What can we do today (i.e.015)? Same beam from Linac 3 (0 A) into LEIR into PS ( bunches ) PS gymnastics Batch compression h = 16 -> 18 -> 1 (100 ns) 1 SPS injections Spaced by 00 ns (resp. 150 ns) Resulting beam SPS train: 4 bunches of 1.4 x10 8 Pb 8+ Transverse emittances ~0.85 m Spacing 3x100 ns + 1x00 (resp. 150) ns 460 (resp. 530) bunches per LHC ring in 19 (resp. ) injections from SPS Luminosity increase ~5% (resp. 47%)
Ar / Xe Other species Will be studied/produced starting in 013 in ECR/RFQ/Linac3, in view of fixed target runs for NA61 in 014/15. Could be available to LHC before LS (but no request) The present baseline is to use the same ECR for all ion species Deuterons Cannot be produced d in present ECR -> Need a new source Cannot be accelerated in Linac3 -> Need a new pre-accelerator Uranium (No official request) Many safety/handling issues
Conclusions With the present injector complex, increasing the number of bunches seems to be the only route for a marginally higher luminosity, and at the expense of a longer LHC filling time If we are to implement the suggested improvements in order to reach the required Pb-Pb luminosity (provided the LHC can digest it), it is more than time to start the RnD on all parts of the injector chain. Ar and Xe will be available after LS1 (parameter list still to be defined and optimised) but other species, if desired, would come in addition, and require more studies, in particular a new source &pre pre-accelerator for deuterons, or safety and handling issues for Uranium.
THANK YOU FOR YOUR ATTENTION!
Nominal scheme 4 injections Nb of bunches Pb ions / (future) LHC bunch Harmonic number / Frequency LEIR (9 10 8 Pb ions / 3.6 s) PS after 1 st splitting 4.5 10 8 16 14-1-4 PS after nd splitting 4 pairs 1. 10 8 Bunch splitting & l Blow-up 4-1 -169-43 SPS at injection (43. s flat-bot), after 13 (1, 8) transfers from PS SPS at extraction 5 (3, 8) pairs 5 (3, 8) 9 10 7 Q SPS = 0.05 00 MHz 100 MHz + 00 MHz LHC at injection, after 1 transfers from SPS 59 7 10 7 400 MHz * = 0.5 m -> L = 10 7 cm - s -1
Present scheme ( intermediate in 011) 7 injections LEIR (9 10 8 Pb ions / 3.6 s) Nb of bunches Pb ions / (future) LHC bunch Harmonic number / Frequency PS (NO splitting) bunch spacing = 00ns 16 14-1-4 4-1 -169-43 SPS at extraction, after 1 transfers from PS, Batch spacing = 00 ns as well LHC at injection, after 15 transfers from SPS 4 ~340 1.4 10 8 1. 10 8 00 MHz 400 MHz * = 1 m -> L = 5.10 6 cm - s -1
Possible scheme for 015 7 injections LEIR (9 10 8 Pb ions / 3.6 s) Nb of bunches Pb ions / (future) LHC bunch Harmonic number / Frequency PS batch compression bunch spacing = 100ns 16 18-1 -169 SPS at extraction, after 1 transfers from PS, Batch spacing = 00 ns ( resp 150ns) LHC at injection, after 19 (resp ) transfers from SPS 4 ~460 (530) 1.4 10 8 1. 10 8 00 MHz 400 MHz * = 0.5 m -> L =.5x10 7 cm - s -1 (resp L= 3.0x10 7 cm - s -1 )
p-pb 00ns scheme in 01 PSB (3 10 10 protons) Nb of bunches 1.5 10 10 Harmonic number / Frequency +1 PS batch compression bunch spacing = 00ns 9-10 0-1 -84 SPS at extraction, after 1 transfers from PS, Batch spacing = 5 ns minimum 4 1. 10 10 00 MHz note: minimum batch spacing of 5ns dictated by protons injection at 6GeV/c Nb of bunches LEIR (9 10 8 Pb ions / 3.6 s) Harmonic number / Frequency PS batch expansion bunch spacing = 00ns 16 14-1-4 4-1 -169 SPS at extraction, 4 after 1 transfers from PS, Batch spacing = 5 ns minimum 1.4 10 8 00 MHz
p-pb 100ns scheme in 01 Nb of bunches 3 10 10 Harmonic number / Frequency PSB (6 10 10 protons ) 9-10 PS batch compression +splitting ; bunch spacing = 100ns SPS at extraction, after 1 transfers from PS, Minimum batch spacing = 5 ns 4 48 1. 10 10 0-1 -84 Note: minimum batch spacing of 5ns dictated by protons injection at 6GeV/c LEIR (9 10 8 Pb ions / 3.6 s) Nb of bunches 4.5 10 8 Harmonic number / Frequency PS batch compression +splitting ; bunch spacing = 100ns SPS at extraction, after 1 transfers from PS, Minimum batch spacing = 5 ns 4 48 16 14-1-4 4-1 -169 14 1.4 10 8 00 MHz
SPS MKP issues Design 5ns with four modules; operating with only 3 allows to operate just below 00ns Possibility to go down to 150ns with help of transverse damper? Note with Q0 we are presently limited to minimum 00ns PFL or PFN cable was foreseen for 115ns at =5.45, now =7.31, PFN operate just under 00ns 50ns @ =7.31 not excluded but also ~30 new, shorter magnets (time, money, manpower)
Lumi scaling vs SPS injection kicker rise time Beam PS bunches Bunch spacing SPS Kicker Bunches in SPS SPS train length SPS > LHC bunches in LHC bunch intensity lumi % 100 ns nominal 4 100 5 48 6075 1 576 0.7 40 50ns ; 00ns kicker 4 50 00 48 4000 17 816 07 0.7 57 50ns ; 150ns kicker 4 50 150 48 3450 19 91 0.7 63 50ns ; 100ns kicker 4 50 100 48 900 1056 0.7 73 50ns ; 50ns kicker 4 50 50 48 350 6 148 0.7 87 00 ns no split 00ns kick 00 00 4 4600 15 360 1.4 100 100 ns no split 00ns kick 100 00 4 3400 19 456 1.4 17 100 ns no split 150ns kick 100 150 4 850 58 1.4 147 50ns unsplit ; 00ns kicker 50 00 4 800 3 55 1.4 153 100 ns no split 100ns kick 100 100 4 300 6 64 1.4 173 50ns unsplit ; 150ns kicker 50 150 4 50 7 648 1.4 180 50ns unsplit ; 100ns kicker 50 100 4 1700 3 768 1.4 13 50ns; double I; 00ns kicker 4 50 00 48 4000 17 816 1.4 7 50ns; double I; 150ns kicker 4 50 150 48 3450 19 91 1.4 53 50ns; double I; 100 ns kicker 4 50 100 48 900 1056 1.4 93 50ns; double I ; 50ns kicker 4 50 50 48 350 6 148 1.4 347