lhc & fixed target ion requirements

D.Manglunki, IEFC Workshop, 8 March 2012

Ions in the SPS D.Manglunki

Special acknowledgements to T.Bohl, C.Carli, E.Carlier, H.Damerau, L.Ducimetière, I.Efthymiopoulos, R.Garoby, M.Gazdzicki,

S.Gilardoni, M.Gruwe, T.Hakulinen, S.Hancock, S.Hutchins,J.Jowett, D.Küchler, P.Odier, Y.Papaphilipou, R.Planeta, S.Reignier,…


LHC & fixed target ion requirements

LHC Fixed target2012 Pb-p Be (fragmented Pb)

2013 LS12014 Primary Ar2015 Pb-Pb Primary Xe2016 Pb-Pb Primary Pb2017 Pb-p (!) “2018 LS22019 Pb-Pb Primary Pb2020 Pb-p “2021 Ar-Ar “2022 LS32023 HL Pb-Pb ( &d-Pb?) ???


Fixed target ion beams in the LHC era

In order to optimize the resources, it had been decided right from the start to use the LHC beams from the injector chain, and adapt them to the needs of the fixed target users, instead of designing optimized beams for every purpose. This has allowed to gain experience in 2010 with the production of the nominal (100ns) beam in LEIR/PS/SPS while delivering the EARLY beam to the LHCDue to unavailability of other species, fragmented Pb (Be) has been delivered to NA61 in 2011 (tests in 2010)

13, 20, 40, 75, 150 AGeV/c Also primary Pb at 80AGeV/c after proton stop In 2012: fragmented Pb (Be) at 13, 20, 30AGeV/c

We will gain experience with the Ar beam for LHC in 2013 while commissioning Ar in ECR/RFQ/Linac3 (see yesterday’s talk), and delivering the FT beam to the North Area in 2014. Two big issues:

Beam structure at extraction Slow extraction of primary ions in the presence of high intensity protons in the complex


RF ON

RF OFF

h frev

fmin

fcav

rev

VCO

“Fixed frequency” acceleration

200 MHz travelling wave cavities fixed tuned, wide-band (199.5 to 200.4 MHz), not wide enough for Pb Ion acceleration using

fixed harmonic acceleration (198.5 to 200.4 MHz) Variable harmonic number (fixed frequency)

acceleration is used instead

Cavity/amplifier risetime ~ 1 ms, beam ~ 6.6 ms, Trev ~23.1 ms

RF is turned on at cavity frequency as beam passes, then turned off to adjust RF phase, ready for next beam passage. Phase adjusted using modulated frequency via VCO At top energy, b~1, technique can be switched off – normal situation


Time structure

Present beam accelerated on fixed frequency and occupies ~40% of the SPS circumference in one train.RF is turned off prior to extraction but bunch/batch structures subsists Modifications to the beam control:

Still occupy 40% of SPS but over 2,3, or 4 equally spaced trains (as was the case for ion operation in 1990s with analog system)

Debunch at proton equivalent momentum of 26GeV/c then recapture on fixed harmonic acceleration

For low energy Ar: possibility of using fixed harmonic from the startMDs start this year


Slow extraction of primary ions in the presence of high intensity protons in the complex

In the past, heavy ion run in SPS implied no proton (Interlcok at Linac level); now in parallel with CNGS & LHC proton beamsRadiological hazard: although both highly improbable, two mechanisms could cause the extraction of a high intensity proton) beam in the North Area, while the TAX need to be open for the low intensity primary ion beam

Injection of a high intensity proton beam on the ion cycle Slow extraction elements pulsing during a high intensity proton cycle

(Apparently) simple solution: when in “primary ion mode” measure the circulating current Inhibit extraction elements above given threshold (2x1011 charges)

…which turned out to be a large integration project (BE, TE, EN, GS, DGS…) over large part of SPS (BA5, BA3, BA2)

All actors very conscious of constraints for personnel protection Technical specification (eventually) starting to converge Equipments ordered or delivered; BCT will be installed in next TS Project can be completed in LS1 provided cabling can be performed


Technical specification EDMS 1146023 For redundancy, 2 new BCTs installed in BA5 (+1 Fast BCT for calibration)2 independent ways of communication (fiber optics & copper)Acting on MST and MSE power suppliesIf intensity over 2x1011 charges, Inhibit MSE and MST:

if requested current =0 OK If requested current >0, force zero, trip

power supply on non-resetable fault (DSO), dump beam.

Additional DCCTs in power supply for current self-check Connection with LOKN for protons


Future beams for LHC Pb-p in 2012 and later

Schemes for 200ns and 100ns bunch spacing Increased luminosity Pb-Pb after LS1

Limited to +25% with current hardware (+50% with 150 ns batch spacing)

Ar-Ar in 2021 (at the earliest) HL Pb-Pb after LS3

List of upgrades


p-Pb 200ns scheme in 2012

LEIR

PS batch expansion bunch spacing = 200ns

SPS at extraction,after 12 transfers from PS,Batch spacing = 225 ns minimum

(9 108 Pb ions / 3.6 s)

1.4 108

Harmonic number / Frequenc

y2

24-21-169

16–14-12-24

200 MHz

2

Nb of bunches

2

24

PSB

PS batch compressionbunch spacing = 200ns

SPS at extraction,after 12 transfers from PS,Batch spacing = 225 ns minimum

(3 1010 protons)

1.2 1010


y2+1

20-21-84

9-10

200 MHz

2

Nb of bunches

2

24

1.5 1010

note: minimum batch spacing of 225ns dictated by protons injection at 26GeV/c


p-Pb 100ns scheme in 2012

PSB

PS batch compression+splitting ; bunch spacing = 100ns

SPS at extraction,after 12 transfers from PS,Minimum batch spacing = 225 ns

(6 1010 protons )

1.2 1010


y

Nb of bunches

LEIR

SPS at extraction,after 12 transfers from PS,Minimum batch spacing = 225 ns

(9 108 Pb ions / 3.6 s)

1.4 108


y2

24-21-169

16–14-12-24

200 MHz

2

Nb of bunches

4

48

4

48

PS batch expansion+splitting ; bunch spacing = 100ns

2

20-21-84

9-10

3 1010

4.5 108

Note: minimum batch spacing of 225ns dictated by protons injection at 26GeV/c


Luminosity increaseNote: current brightness performance is already 2 x design

b functions at IP Transverse emittancesIntensity per bunchNumber of bunches -> reduce spacing

Nominal was 100 ns / 225 ns Present scheme is 200 ns / 200 ns ALICE asks for 50ns

…but number of bunches will not be x4Influence of LHC injection kicker (0.9ms) & abort gap (3ms)Effect of SPS kicker rise time:

12 injections in SPS (present limit due to ROCS) Scaling Luminosity as NB x IB

2


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

40 60 80 100 120 140 160 180 200 220 2400

50

100

150

200

250

300

350

400

50ns (double injector perf)

50ns (present injector perf)

Present (2011)

100ns no splitting (present perf)

Nominal (as design)


Possible scheme for Pb-Pb in 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%)


Possible scheme for Pb-Pb in 2015

LEIR

PS batch compression bunch spacing = 100ns

SPS at extraction,after 12 transfers from PS,Batch spacing = 200 ns ( resp 150ns)

LHC at injection,after 19 (resp 22) transfers from SPS

(9 108 Pb ions / 3.6 s)

Pb ions / (future) LHC

bunch

1.4 108

1.2 108

b* = 0.5 m -> L = 2.5x1027 cm-2 s-1

(resp L= 3.0x1027 cm-2 s-1)


y2

-16916–18-21

200 MHz

400 MHz

7 injections2

Nb of bunches

2

24

~460(530)


Possible route to 50ns for HL Pb-PbDesign 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 SPS12 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


SPS MKP upgrade

Design: 225ns with four modulesOperating with only three modules allows to operate just below 200ns

Possibility to go down to 150ns with help of transverse damper? Note with Q20 we are presently limited to minimum 200ns

PFL or “PFN cable” was foreseen for 115ns at g=5.45 , now g=7.31, PFN operate just under 200ns50ns @ g=7.31“not excluded” but also ~30 new, shorter magnets (time, money, manpower)


Present issue in the SPS for the LHC beam

RF Noise, IBS & DQ on SPS flat bottom First batch suffers 40 more seconds on flat

bottom:lower intensity/bunch, transverse emittance blowup

Can Q20 help? (larger beam sizes, smaller IBS & DQ )

RF Noise? Splitting to bunchlets

& Reinstall 100 MHz system (cavities, amplifiers, beam control)?


ConclusionsAr and Xe will be available after LS1 for fixed target experimentsCabling the beam interlock system during LS1 is vital for the parallel operation of protons and FT ions in 2014 and beyond.With the present injector complex, increasing the number of bunches is the only route for a marginally higher luminosity, and at the expense of a longer LHC filling timeIf we are to implement the suggested improvements in order to reach the required Pb-Pb luminosity, RnD has to start on

MKP Reassess advantage of splitting to bunchlets Possibility of more injections/longer cycle …and of course other parts of the complex


THANK YOU FOR YOUR ATTENTION!


CHECK & COMPARATOR

UNITBE/BI/ PI 3101

CHECK & COMPARATOR

UNITBE/BI/ PI 3101

PLC

PATCH 2

PATCH 1

DCCT 1

DCCT 2

RA 2713

RA 2714

C1

C1 C3

C3

C2 C4

C2 C4

B19SMB19SF

B19SMB19SF

B12SF

B12SF

B19SF

B19SF

B12SM

B12SM

OPTICAL FIBER

BA 50 BA 50 DCCT

Copper cable

LOW_IB_STATUS_ALOW_IB_STATUS_B

IN_CHECK_STATUS_AIN_CHECK_STATUS_B


DCCT ELECTRONICS

DCCT 1

I beam

I cal

TIMINGUNIT

INTERLOCK SYSTEM

DIAGNOSTICUNIT

Start Check

FRONT END COMPUTER

Analog signal

Status

Status

Status

DCCT ELECTRONICS

DCCT 2

I beam

I cal

TIMINGUNIT

INTERLOCK SYSTEM

DIAGNOSTICUNIT

Start Check

FRONT END COMPUTER

Analog signal

Status

Status

Status

CHECK & COMPARATOR

UNIT

CHECK & COMPARATOR

UNIT


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


Nominal scheme

LEIR

PS after 1st splitting

PS after 2nd splitting

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

SPS at extraction

LHC at injection,after 12 transfers from SPS

(9 108 Pb ions / 3.6 s)2.25 108

Pb ions / (future) LHC

bunch

1.2 108

9 107

7 107

2

4

Nb of bunches

4 pairs

52 (32, 8) pairs

52 (32, 8)

592

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


y2

24-21-169-423

16–14-12-24

200 MHz

100 MHz + 200 MHz

400 MHz

Bunch splitting & el

Blow-up

D QSPS= 0.05

4 injections


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 nsSPS

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)


BeamPS bunches Bunch spacing

SPS Kicker

Bunches in SPS

SPS train length

SPS > LHC

bunches in LHC bunch intensity lumi %

100 ns nominal 4 100 225 48 6075 12 576 0.7 4050ns ; 200ns kicker 4 50 200 48 4000 17 816 0.7 5750ns ; 150ns kicker 4 50 150 48 3450 19 912 0.7 6350ns ; 100ns kicker 4 50 100 48 2900 22 1056 0.7 7350ns ; 50ns kicker 4 50 50 48 2350 26 1248 0.7 87200 ns no split 200ns kick 2 200 200 24 4600 15 360 1.4 100100 ns no split 200ns kick 2 100 200 24 3400 19 456 1.4 127100 ns no split 150ns kick 2 100 150 24 2850 22 528 1.4 14750ns unsplit ; 200ns kicker 2 50 200 24 2800 23 552 1.4 153100 ns no split 100ns kick 2 100 100 24 2300 26 624 1.4 17350ns unsplit ; 150ns kicker 2 50 150 24 2250 27 648 1.4 18050ns unsplit ; 100ns kicker 2 50 100 24 1700 32 768 1.4 21350ns; double I; 200ns kicker 4 50 200 48 4000 17 816 1.4 22750ns; double I; 150ns kicker 4 50 150 48 3450 19 912 1.4 25350ns; double I; 100 ns kicker 4 50 100 48 2900 22 1056 1.4 29350ns; double I ; 50ns kicker 4 50 50 48 2350 26 1248 1.4 347

Lumi scaling vs SPS injection kicker rise time

lhc & fixed target ion requirements

Documents