D.Manglunki, LIU Ions, 30 July 2013

Pb for LHC: requirements summary

D.Manglunki

D.Manglunki, LIU Ions, 30 July 2013

Why upgrade?

ALICE Upgrade approved: Request for peak luminosity “higher than L=6x1027cm-2.s-1” after LS2

Programme in coming years:

HL Pb-Pb (today)

Ar & Xe LHC SPS fixed target2015 Pb-Pb (100ns) Primary Ar2016 Pb-Pb2017 Pb-p Primary Xe2018 LS22019 Pb-Pb Primary Pb2020 Pb-p “2021 Ar-Ar? “2022 LS32023 HL Pb-Pb

D.Manglunki, LIU Ions, 30 July 2013

Luminosity increaseNote: current brightness performance is already 2 x design

b functions at IP (/2 to 0.5m)Transverse emittances (/2 by energy )Intensity per bunch (=)Number of bunches (by reducing spacing)

Influence of LHC injection kicker (0.9ms) & abort gap (3ms)

Increase nr of injections in SPS (present limits = 12 due to ROCS; 15 due to RF)

One can shoot for L=7x1027cm-2.s-1

D.Manglunki, LIU Ions, 30 July 2013

100/50 ns scheme

PS batch compression + rebucketing Bunch spacing = 100ns

SPS at extraction,after 24 transfers from PS,Batch spacing = 50 ns

LHC at injection,after 19 transfers from SPS

LEIR(1.1 109 Pb ions / 3.6 s)

2.2 108

b* = 0.4 m -> L = 7x1027 cm-2 s-1

Harmonic number

2

16–18-21-169

35640

4653…4620

6 injections

2

Nb of bunches

2

48

~912

1.7 108

100ns 50ns

100ns 3.8 108

5.5 108

Pb ions/bunch

D.Manglunki, LIU Ions, 30 July 2013

Route to 100/50ns

Linac 3 / LEIR produce similar performance as in 2013:

2 bunches of ~5.5 108 Pb54+ PS gymnastics

Batch compression to 100ns h = 16 -> 18 -> 21(no need for new cavities, 10MHz system exists)

2 bunches > 2 x108 Pb82+ into SPS24 SPS injections spaced by 50ns

Similar bunch quality as present beam

48 bunches of ~1.7x108 Pb82+

Transverse emittances ~0.85mm

Alternating 100/50ns spacing19 injections / LHC ring -> 912 bunches /ring

D.Manglunki, LIU Ions, 30 July 2013

Plan B (in case no SPS injection upgrade)

Double current from Linac 3 (~50mA)LEIR

Produce 2 bunches of ~1.1 109 Pb54+ in same emittance (i.e. twice today)

PS gymnastics

As “old nominal scheme” 4 bunches > 1.4 x108 Pb82+

OR Batch compression to 100ns h = 16 -> 18 -> 21Splitting to 50 ns; 4 bunches > 1.4 x108 Pb82+ into SPS

Issues:

splitting to 50ns at high energy imposes some gamma-transition distortion

splitting to 50ns at low energy imposes acceleration at 20MHz

D.Manglunki, LIU Ions, 30 July 2013

Luminosity scaling (%) vs SPS injection kicker rise time (ns), 24 PS injections into SPS

D.Manglunki, LIU Ions, 30 July 2013

Actions/Issues since 2012 “Brainstorm”

Is the ECR source the bottleneck?RFQ rematching Multiple charge acceleration: Study still to be reactivated Faster repetition rate

OK for source and Linac

Power supplies & magnets in ETL, planned for consolidation

LEIR injection to be checked

Source & LINAC

D.Manglunki, LIU Ions, 30 July 2013

LEIR

Study loss at beginning of ramp (different Bdot, tunes,…)Intensity limits (tests with longer flat bottom until higher intensity from Linac)Vacuum (limit loss by cleaner dump)

PSLongitudinal acceptance for suggested RF gymnasticsAlternate schemes (Gamma-t jump at flat top, acceleration on 20MHz)Vacuum

Issues on flat bottom

RF noise

Space charge & IBS (Q20)Increase number of injectionsInjection kicker rise time 50ns

SPS

D.Manglunki, LIU Ions, 30 July 2013

THANK YOU FOR YOUR ATTENTION!