LHC Machine Advisory Committee, Dec 7 th, 07D. Manglunki1 Ion commissioning in the SPS D. Manglunki presenting the work of M.Albert, G.Arduini, Ph.Baudrenghien,

D. ManglunkiLHC Machine Advisory Committee, Dec 7th, ‘07

1

Ion commissioning in the SPS

D. Manglunkipresenting the work of

M.Albert, G.Arduini, Ph.Baudrenghien, G.Bellodi, P.Beloshitsky, E.Benedetto, Th.Bohl, C.Bracco, H.Braun, R.Bruce, C.Carli, E.Carlier, M.Chanel,

H.Damerau, B.Dehning, S.Gilardoni, S.Hancock, B.Holzer, D.Jacquet, J.Jowett, L.Jensen, V.Kain, D.Küchler, M.Martini, E.Métral, S.Maury,

L.Normann, S.Pasinelli, G.Papotti, S.Redaelli, M.Schokker, R.Scrivens, J.L.Vallet, B.Vandorpe, J.Wenninger, U.Wehrle, Th.Weiler, C.Zamantzas,

and Linac, LEIR, PS & SPS operations teams


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Outline

• Reminders: Parameters, Nominal scheme, early scheme• Actions performed on injector chain since last December

(LHCMAC20)• SPS commissioning

– Injection, acceleration, extraction of Early beam– Collimation studies– Issues on front porch

• Progress towards nominal beam– LEIR– PS– SPS

• Beam requests for 2008-2009– Source + Linac 3 (2008)– PS, SPS (2008 or 9?)


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Reminder: key parameters(Nominal beam)

ECR Source

Linac 3 LEIR PS SPS LHC

Output energy 2.5 KeV/u 4.2 MeV/u 72.2 MeV/u 5.9 GeV/u 177 GeV/u

2.76 TeV/u

208Pb charge state 29+ 29+ 54+ 54+ 54+ 82+ 82+ 82+

Output B r [Tm] 2.12 1.14 4.80 86.7 57.3 1500 23350

bunches/ring 2 (1/8 of PS) 4 52 592

ions/pulse 9 109 1.15 109 9 108 4.8 108 4.7 109 4.1 1010

ions/LHC bunch 1.1 1010. 1.45 109 2.25 108 1.2 108 9 107 7 107

bunch spacing [ns]

100 100 100

e*(norm. rms) [mm]

0.07 0.25 0.7 1.0 1.2 1.5

(e phys., rms) [mm]

30 2.6 1.75 0.14 0.0063 0.0005

Repetition time [s] 0.2-0.4 0.2-0.4 3.6 3.6 ~50 ~10’fill/ring


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Reminder: Nominal scheme (L=1E27cm-2s-1)

LEIR

PS after splitting

SPS at injection (43.2 s flat-bottom),after 13 (12, 8) transfers from PS

SPS at extraction,after 13 (12, 8) transfers from PS

LHC at injection,after 12 transfers from SPS

(9 108 Pb ions / 3.6 s)

2.25 108

Pb ions / (future) LHC bunch

9 107

7 107

b* = 0.5 m -> L = 1027 cm-2 s-1

Harmonic number /

Frequency

2

24-21-169-423

16–14-12-24

200 MHz

200 MHz

400 MHz

4 injections

12 107


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Reminder: Early scheme (L=5E25cm-2s-1)

LEIR

PS at injection and acceleration

TT2 after stripper

SPS at injection (7.2 s flat-bottom),after 3 (4) transfers from PS

SPS at extraction,after 3 (4) transfers from PS

LHC at injection,after 16 transfers from SPS

(2.5 108 Pb ions / 2.4 s)

1

1

Nb of bunches

1

3 (4)

3 (4)

about 60

b* = 1 m -> L = 5 1025 cm-2 s-1

Harmonic number /

Frequency

1

16 + 169

16

200 MHz

200 MHz

400 MHz

Pb ions / (future) LHC bunch

2.5 108

1.2 108

9 107

7 107

PS at extraction

1 injection


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Done in 2007 in view of the Early Beam(List of Actions MAC Dec 2006)

• LEIR– Improve intensity

reliability/reproducibilityIntensity OK (1.2E10 charges/ 2.2E8 ions)Run routinely from CCC (LEIR OP daytime,

SPS OP nights & week-ends)

eL = 40meVs/n >> 25meVs/neH ~0.5mm, eV ~0.18mm,Extraction efficiency > 80%synchronized to PSenergy matched


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Done in 2007 in view of the Early Beam(List of Actions LHCMAC 20)

• PS– RF: radial loop pick-up sensitivity boost by 12dB

(most probable cause of the ~30% losses seen at the start of acceleration)

Done; but also other debugging helped improve losses:- frequency programme - crosstalk from synthesizer

dedicated to ions 30dB attenuation

Ch1: Radial position Ch2: Phase discriminatorCh3:Beam current transformerCh4: Resistive wall pick-up

Ch1: Resistive wall pick-upCh2: Phase discriminatorCh3: B-train upCh4: B-train down


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Done in 2007 in view of the Early Beam(List of Actions LHCMAC 20)

• PS– Controls

ABS PPM copy

– Power supply for F16.QFO205 in TT2

– Cooling water for PI.SMH26

– Modification of stripper movement acquisition (outside vacuum)

ABS reactivatedPPM copy works

Upgraded to 450A for full low beta

Modified, no intervention needed any more prior to dedicated MDs

Modified, easier maintenance


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Also done in 2007

• Source– improved performance and stability– operation with Pb29+

reduced radiation from the linac tanks– operation with two ovens

not as effective as expected (factor 1.5 instead of 2 in operation time)– reduced lead consumption to ~1.0-1.5mg/h

But lack of oven spare parts gave some troubles during the last oven refills– hexapole and complete set of solenoids ordered

(most critical spare parts concerning delivery time)• Linac 3

– new performance record: 31 emA of Pb54+ out of the linac (but needs more stability)

– read back of ramping/debuncher cavities installed (was write-only)– remote reset installed for tank2 and 3 (no more car trip needed from CCC)– modified stripper mechanism (no more losses of stripper frames)

• TT2/TT10– Complete rematching with full low beta scheme


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SPS commissioning programme

• Planned:– Injection, acceleration, extraction of Early beam– IBS & space charge studies on front porch at 17 Z GeV/c with nominal intensities – Collimation studies at 270 Z GeV/c with nominal intensities – Slow extraction to North Area for crystal channeling studies

• Achieved:– Early Beam: Injection of 4 bunches, capture, acceleration, extraction

Extraction at low intensity No synchronization

– IBS & space charge studies data still under analysis Alternate schemes under study for nominal beam

– Collimation: loss maps at 17 & 270 Z GeV/c Partly at low intensity


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• Achieved/Planned MD time:– 12 days (vs ~35) parallel– 7x24h (ok) + 1x8h (vs 3x8h ) dedicated

• Issues and Problems encountered:– Linac 3

Source Quad in transfer line

– LEIR RF cavities

– PS New ion cycle PFWs & W8L trips Stuck beam stopper Vacuum leak on dump 48

– TT2 QDE207 (wrong polarity, frequent trips)

– SPS Late delivery of RF hardware (priority of LHC protons) Injection kicker prepulse distribution, conflicts with LHC p+ & CNGS) 2 main magnets exchanges Long setting up for each cycle, only 1 “user” for 3 cycles

SPS MDs in 2007


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3 SPS Cycles / 1 “user”

• Parallel MD cycle– allowed to perform first injection, debug hardware, prepare acceleration – Single injection flat bottom– acceleration through transition

(up to 70 Z GeV/c)• EARLY LHC filling cycle (dedicated)

– 1-4 injections– acceleration to 450 Z GeV/c– extraction– with coastable flat bottom

• Loss maps studies cycle (dedicated)– 1-4 injections – 270 Z GeV/c coastable plateau


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• Up to 4 injections• Lower intensity but brighter than expected• DQSC = 0.092 on flat bottom (!)• Transverse IBS growth times ~ 3 minutes • Stable IBS longitudinal (growth time ~ -2

minutes)

Early beam at SPS injection

Parameter Design Achieved Unit

I 9.8 8.9 (*) E9 charges

e*H 1.0 0.8 mm

e*V 1.0 0.8 mm

e// 0.05 0.03 eVs/u

tB 4 3.6 ns

Dp/p 1.2 0.9 E-3


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• New working point Qh = 26.20 (26.13) ; Qv = 26.25 (26.19)• VRF dips from 3.5Mv to 2.6 MV at each injection• Bunch shortening observed during flat bottom

Flat bottom


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• 81% transmission• 23% total front porch loss• 12% uncaptured beam (capture loss, loss along flat

bottom)

Flat bottom and acceleration


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Flat Top


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• Benefited from TI2 test the preceding week-end– Same magnetic rigidity etc… first time right!– Allowed to measure extracted beam properties

• No synchronization of extracted beam (yet)• (*) Extracted beam was ~20% of design value due to vacuum leak in

PS, but 90% design intensity had been accelerated 2 weeks before extraction

Extraction to TT60

Parameter Design Achieved Unit

I 30 6 (*) E9 charges

N 3.6 0.7 (*) E8 ions

eH 6E-3 6E-3 p.mm.mrad

eV 6E-3 6E-3 p.mm.mrad

e*H 1.2 1.2 mm

e*V 1.2 1.2 mm


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• LHC secondary collimator prototype installed in SPS

(2 independent carbon jaws in horizontal plane)• Jaws moved in and out during operation • BLM signals recorded from all 216 monitors in the

ring• September 2007: LHC BLMs installed on predicted

ion-specific loss locations

Collimation studies

5250 5275 5300 5325 5350 5375 5400S

0.08

0.06

0.04

0.02

0.02

0.04

0.06

0.08X

AX

AX

0.14

0.12

0.09

0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.01

5250 5275 5300 5325 5350 5375 5400Sm

0.08

0.06

0.04

0.02

0.02

0.04

0.06

0.08xm


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Collimation studies: 17 Z GeV/c

Ions

Protons

Zoom on sector 5Zoom on BLMs after collimator, ions

Measured signalSim. # nucl. lost close to BLM (norm.)

• Good qualitative agreement, but exact ratio not matching.• Could be because the amount of material between loss and BLM

differs!• More simulations needed


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Collimation studies: 270 Z GeV/c

protons(nov. 2006)

Zoom on sector 5

protons

ions

Zoom on BLMs after collimator

Measured signal

Sim. # nucl. lost close to BLM (norm.)

ions


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• Method: “coasts” at injection energyand measure:– Emittances with wire scanner

Alternating planes manually, every “cycle” Correct for blowup by multiple scattering in each wire scan

– Longitudinal bunch profiles– Beam Current Transformer (DC and fast)

• Scanned horizontal and vertical tunes• Varied intensity (once) at LEIR level• Correlation of different instruments not straightforward

=> Long analysis process => Preliminary data

Space charge and IBS studies on front porch


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• Transverse emittance:– No dramatic blow-up seen on good

coasts at injection energy– Need better fitting than in online

program


• Longitudinal Profiles:– Bunch typically loses half intensity in

about 1-1.5 minute (actual movie time = 2’)


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• Lifetime seems adequate for Early scheme, not so clear for Nominal

• Loss mechanisms not yet clearly identified (RF noise?)• Analysis continuing for emittance • Correction of measurements for multiple scattering on

wire



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Progress towards nominal beam: LEIR

• I~ 4x1010 charges accelerated• h=2• bunches<200ns• el<50meVs/n/b

• eh~0.5mm,ev~0.18mm


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Progress towards nominal beam

• PS: No effort possible on nominal beam in 2007 (priorities)

SPS : Current studies to get rid of 43.2s plateau– “Nominal” beam in LEIR and PS– Shorter flat bottom in SPS

10.8 s for 4 injections 18.0 s for 6 injections

– Up to 80% of “Nominal” current with same LHC filling time ~650s/ring– ALICE studying 75ns possibility


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Summary 2007

• LEIR– Improved diagnostics– Reliably run from CCC– Progress towards nominal beam

• PS:– New cycle with lower intermediate plateau– Lots of debugging, improved transmission– Finalized low-beta optics; complete rematching of transfer line– No effort possible on nominal beam (priority to proton and early beams)– Vacuum leak at end of run

• SPS:– RF hardware late delivery; first 2 dedicated MD sessions replaced by magnet

repair– Injection, acceleration, extraction of early beam– Loss maps studies at 17 and 270 Z GeV/c– Studies of beam behaviour on injection plateau– No time for slow extraction in North Area (crystal channeling)


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Requests for 2008:4 -6 weeks source & Linac 3

• Source– Commission 18GHz– commissioning of the source with the 18 GHz generator– to better understand the source behaviour need of a more elaborate

sourcedevelopment programme (oven, bias disk)

– improve radiation shielding– improve situation of spare parts– replacement of both source extraction turbo molecular pumping systems

(no more spares for the controllers available),– the pumps will be exchanged if they fail

• Linac 3– replacement of the Bruker power converter (ITL, ITM) by a modular– solution, budget not yet approved– new vacuum control system to be implemented during the shutdown

2007/08– prepare remote reset of RFQ and tank1 – finish work on the software/hardware of the ramping cavity– if possible emittance measurements with pepper pot system from

KVI/Groningen in the ITL


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Requests for 2008 (or 2009?)8 weeks for LEIR

• LEIR– Injection studies

mismatch, acceptances– Digital Low level RF – Voltage feedback– Finalise nominal beam– Better understanding of machine

chromaticity, lattice deviations, tests of different tunes…– Cooling not fully tested and measured

lifetime and cooling rate depending on current, electrons distribution; systematic measurements needed

– Understand extraction efficiency– Study betatron matching with PS– Full control of Linac3 ramping & debuncher cavities, bumper parameters.– Many applications to write for improving operation

spectra analysis, BIPM measurements, ecool beam trajectory, tune measurement, …– Transformers acquisition for beam survey and vistar– Add transfer lines in LSA??– RF HV Power supplies: finalise solution


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Requests for 2008 (or 2009?)>3 weeks PS (party in parallel with

LEIR?)• PS RF:

– Second iteration for frequency programme– Test new hardware (being built this shutdown) for 423-divider

ejection synchronization– RF gymnastics for nominal beam


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Requests for 2008 (or 2009?)6 weeks for SPS

• SPS RF: (4 weeks parallel + 4 dedicated sessions)– reproduction of results of 2007 with definitive hardware and software– synchronization with LHC at flat top– longitudinal emittance blow-up

• Full extraction of early beam to both TI2 and TI8• Slow Extraction to North Area for crystal channeling studies• Note: ALICE is still requesting 2 weeks of ions

at the end of the first p+ run– … and is interested in a low energy run in any case!

(highest collision energy for heavy ions, even at injection)

Documents

LHC Machine Advisory Committee, Dec 7 th, 07D. Manglunki1 Ion commissioning in the SPS D. Manglunki presenting the work of M.Albert, G.Arduini, Ph.Baudrenghien,