Plans for ions in the injector complex D 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 LS2 & LS3?

Previously on the LHC ion injector chain… “Nominal beam” in Design report L = 1027cm-2s-1 at 7 TeV/c/charge ~600 bunches of 7x107 Pb82+ ions eH,V= 1.2mm b* = 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 (2003) Decision to start with “EARLY” scheme, single bunch from LEIR > PS > SPS Assumed possibility of up to 13 PS injections into SPS

Experience in 2010 (EARLY) and 2011 Linac3 delivers ~30-40% of design (15-20mA vs 50) Additional injections in LEIR Better beam lifetime at low energy in PS thanks to excellent vacuum IBS and DQ on SPS flat bottom less harmful than foreseen “EARLY” run in 2010: 1.2×108 ions/bunch; eH,V= 1.2mm ; L = 3x1025cm-2s-1 at 3.5TeV/c/charge Provisionally demonstrated that bunchlets are unnecessary Raised the bar high for 2011 run (Terribly named) “INTERMEDIATE” run in 2011 (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 200 ns bunch spacing in PS Batch spacing 200ns thanks to shorter SPS injection kicker rise time (only 3 modules at 17GeV/c/charge)

Present scheme (“intermediate” in 2011) LEIR 7 multiturn injections of Linac3 pulse (~15-20mA) 2 bunches of 4.5x108 Pb54+ PS (similar gymnastics as nominal, minus splittings) Batch expansion h = 16 -> 14 -> 12 Rebucketing (was splitting) h = 12 -> 24 Batch expansion h = 24 ->21 Rebucketing h = 21 -> 169 After stripping, 2 bunches of ~3x108 Pb82+ bunch spacing 200 ns SPS 12 injections of PS batches, batch spacing 200 ns 24 bunches of ~1.4x108 Pb82+ (0.9x108 design) Transverse emittances ~0.85mm (1.2 design)

Present issues (which have limited 2011 performance to only 2x 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 & DQ on SPS flat bottom First batch suffers 40 more seconds on flat bottom: lower intensity/bunch, transverse emittance blowup

Users requirements 2012 p-Pb 2015-17 Pb-Pb (+ p-Pb) 2019-21 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 2011 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 2012 No other species requested as of now

Luminosity increase Note: current brightness performance is already 2 x design b functions at IP Transverse emittances Intensity per bunch Number of bunches -> reduce spacing Nominal was 100 ns / 225 ns Present scheme is 200 ns ALICE ask for 50ns …but number of bunches will not be x4 Influence of LHC injection kicker (0.9ms) & abort gap (3ms) Effect of SPS kicker rise time: 12 injections in SPS Scaling Luminosity as NB x IB2

Lumi scaling (%) vs SPS injection kicker rise time (ns)

Possible route to 50ns Design current from Linac 3 (~50mA) LEIR Produce 2 bunches of ~109 Pb54+ in same emittance (i.e. twice today) PS gymnastics Batch compression to 100ns h = 16 -> 18 -> 21 (no need for new cavities, 10MHz system exists) Splitting h = 21 -> 42 (20MHz system exists but VRF acceptance to be checked) 4 bunches > 1.4 x108 Pb82+ into SPS 12 SPS injections spaced by 50ns Similar bunch quality as present beam 48 bunches of ~1.4x108 Pb82+ Transverse emittances ~0.85mm But with 50ns spacing and hopefully less spread in bunch population Note: longer LHC injection time

Necessary studies/upgrades Linac 3 (~50mA) 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 Q20 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.2015) ? Same beam from Linac 3 (20mA) into LEIR into PS (2 bunches…) PS gymnastics Batch compression h = 16 -> 18 -> 21 (100 ns) 12 SPS injections Spaced by 200 ns (resp. 150 ns) Resulting beam SPS train: 24 bunches of 1.4 x108 Pb82+ Transverse emittances ~0.85mm Spacing 3x100 ns + 1x200 (resp. 150) ns 460 (resp. 530) bunches per LHC ring in 19 (resp. 22) injections from SPS Luminosity increase ~25% (resp. 47%)

Other species Ar / Xe Will be studied/produced starting in 2013 in ECR/RFQ/Linac3, in view of fixed target runs for NA61 in 2014/15. Could be available to LHC before LS2 (but no request) The present baseline is to use the same ECR for all ion species Deuterons Cannot be produced 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-accelerator for deuterons, or safety and handling issues for Uranium.