Transcript 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,

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?
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
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
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
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)
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
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)
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
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
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
Users requirements
2012
2015-17
2019-21
p-Pb
Pb-Pb (+ p-Pb)
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

D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
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
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
Lumi scaling (%)
vs SPS injection kicker rise time (ns)
400
350
300
250
50ns (double injector perf)
200
50ns (present injector perf)
150
Present (2011)
100
100ns no splitting (present perf)
Nominal (as design)
50
0
0
50
100
150
200
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
250
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
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
Necessary studies/upgrades
Linac 3 (~50mA)
PS

New ECR source?

Tranverse damper?

Multiple charge
acceleration?

RF gymnastics

Faster Linac rep rate
(10Hz)?
Construction of Linac 5?
LEIR
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)?


loss at acceleration / limits
to be understood

ECOOL?

Transverse damper?
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
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%)
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
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
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
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.
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012
THANK YOU FOR YOUR ATTENTION!
D.Manglunki, Chamonix LHC Performance Workshop, 09 February 2012