LHC Luminosity upgradesL. Rossi
Contribution from: A. Ballarino, Ed Ciapala, M. Karppinen, S. Fartouk, R. Ostojic, S. Russenschuck, L. Tavian, S. Weisz and all taskforce on LHC
Lumi
2nd CERN-MAC 26 April 2010
LHC Lumi Up @ 2nd CERN-MAC 2
What has to be done to allow LHC to reliably reach design luminosity?
• Peak luminosity (1034): the triplet has been designed for the nominal of 55 cm. Design luminosity will requires nominal intensity: collimation to handle 0.54 A, see talk later
• There is margin “everywhere” : chromaticity, quench limit vs. heat deposition…
• Damage level: 300-400 fb-1 (probably most critical is the nested orbit corrector magnet, more margin in the MQX…). Today this is expected not before 2020-2022.
26 April 2010
LHC Lumi Up @ 2nd CERN-MAC 3
Nominal luminosityCaveats
• Long range beam-beam effects may turn to be a limit… opening the X-ing angle is a mitigation.– In this respect the – relatively small – aperture of the present
triplet may already become a limitation.– Other ways to overcome this problem, if it appears before
nominal luminosity (compensating wires…)• Collimation system.
– Insufficient cleaning efficiency.– Insufficient compensation of impedance effect.– To compensate this shortfall, opening the collimators may be
needed
26 April 2010
LHC Lumi Up @ 2nd CERN-MAC 4
What needs to be done to allow LHC to reach ultimate luminosity
• Ultimate peak luminosity (2.3 1034) should come from increase in intensity (0.86 A, in bunches of 1.7 1011 p)
• However present triplet is limited to 1.7 1034 mainly due to heat deposition from collision debris.– Is this a hard limit ?
26 April 2010
LHC Lumi Up @ 2nd CERN-MAC 5
Ultimate luminosity: considerations to make it reliable
• Larger aperture low beta quad is – most probably – necessary because previous limits may become hard:– Long range beam-beam– Collimator– Better shielding against radiation
• Use of all installed cryogenic power per point side (500 W: today there is limitation of 300 W inside the triplet, first due to HX and then to longit. magnet conductance). The 300 W gives the limit L 1.7 1034 above mentioned.
• Probably independent cooling of RF @ P4 is needed to re-establish full cooling power in IP5Left.
• Displacements of Power Converter (and DFBs) of Inner Triplets to far distance, possibly on surface. Cold power based on Sc links needed.
• All this makes that to reach, or to exploit reliably ultimate luminosity, the triplet - and IR region - must be upgraded.
26 April 2010
LHC Lumi Up @ 2nd CERN-MAC 6
Possible LHC lumi (M.Lamont)
26 April 2010
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-5.0E+33
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to nominal - lumi to ultimate - lumi hf.2 - lumi to ultimate to nominalhf.2 - int
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LHC Lumi Up @ 2nd CERN-MAC 7
Phase 1 assessment: summary fromtaskforce @ LMC-10Mar2010 - 1
• Advantage of the Phase 1.– 1.2 to 1.35 better luminosity with present
limitation (collimation and SPS).– Better shielding (factor 2.5) and use of all cryo-
power installed. When all other bottle necks removed this will allow in principle to pass from 1.7 to 3 1034 in Lumi.
– Opening to compensate possible shortfall of present LHC (see previous)
– Separation of cryo-circuit between Arc and IT.26 April 2010
LHC Lumi Up @ 2nd CERN-MAC 8
Phase 1 assessment: summary fromtaskforce @ LMC-10Mar2010 - 2a
• Disadvantage of the Phase 1.– Optics much more rigid;
• requires special scheme. Aberration sat the limit of LHC correction capability. Longer magnets (same technology) does not help.
• 30 cm is more difficult than 55 cm of the present LHC. Better solution found with = 40 cm offering a 3 sigma margin per beam (which was part of the initial goal) but only 1.2 gain in lumi over nominal. Today we are limited by a single element. IR upgrade will use all the margins in the whole ring.
– To change this:• modification in MS positions and replacement of a few magnets, • additional IR collimators to catch higher losses in IR matching section (lower aperture
due to higher beta* in the not-changed magnets• Use ultimate strength in the sextupoles, NEW powering scheme of MQT corrector
families.– Logistics is hard: The logistic for ancillary equipment is hard.
• A solution NOT fully satisfactory has been found for IP1; more difficult for IP5. • A real long term solution devised (see S. Weisz in Chamonix and SC links by A. Ballarino).
This solution should be integrated in a more global study for radiation protection of electronics26 April 2010
LHC Lumi Up @ 2nd CERN-MAC 9
Phase 1 assessment: summary fromtaskforce @ LMC-10Mar2010 - 2b
• Disadvantage of the Phase 1– The use of the same refrigerator for RF and Arc-IT in 4-5 makes 5L
(CMS) weaker in term of cryo-power for high luminosity.– The new schedule of LHC: we will not be at nominal before 2014-
15 at the very best, and the 300-400 fb-1 are foreseen well beyond 2020.
– Because of past and future delay (splice consolidation) the IT phase 1 cannot be installed anyway before 2016/17.
– 1 year optimistic installation time + needed time for a new commissioning of the machine
– The fairly long stop, and the relatively low gain factor: 2 at max, 1.2 at min) require 2.5 to 5 years just to catch up. Then other long stops will be required for L > 2-3 1034.
26 April 2010
LHC Lumi Up @ 2nd CERN-MAC 10
Phase 1 assessment: summary fromtaskforce @ LMC-10Mar2010 – 3
• Recommendation about Phase 1– Stop the phase 1 project– Keep going on the R&D of Phase 1 that is necessary
because of long lead time development;– Decision in 2013/2014, after LHC behaviour near nominal
will be known, the best technology for upgrade. We can’t start construction before half 2013. Decision in 2014 to have it by 2018-2020.
– Put the IT upgrade in a global pictures, preceded by all consolidation or improvement needed to make it most effective and compatible with other equipment.
26 April 2010
LHC Lumi Up @ 2nd CERN-MAC 11
What needs to be done for 5-6x1034 ultimate intensity - 0.86 A - is assumed
• Improve some correctors– Commissioning @ 600-650 A the lattice sextupoles– New MQT corrector scheme using existing spare 600 A bus bars
• Re-commissioning DS quads at higher gradient• Review MSs
– Change of New Q5/Q4 (larger aperture), with new stronger corrector orbit, displacements of few magnets
– Larger aperture D2• (may be other actions, more quads in points 6 and 7)• Displacement of Power Converters & DFBs at least of Inner Triplets
but also of OTHER equipment on surface by means of SC links. • Cryo-plant for RF in point 4 : 5-7 kW @ 4.5 K
26 April 2010
LHC Lumi Up @ 2nd CERN-MAC 12
The main ingredient of the upgrade(in addition to beam intensity)
• High Gradient Quads, with Bpeak 13-15 T. Higher field quadrupoles translate in higher gradient/shorter length or larger aperture/same length or a mix . US-LARP engaged to produce proof by 2013. Construction is 1 year more than Nb-Ti : by 2018 is a prudent assumption. as small as 22 cm are possible with a factor 2.5 in luminosity by itself, if coupled with a mechanism to compensate the geometrical reduction. If a new way of correcting chromatic aberration could be found, as small as 10-12 cm can be eventually envisaged.
• Crab Cavities: this is the best candidate for exploiting small (for around nominal only +15%). However it should be underlined that today Crab Cavities are not validated for LHC , not even conceptually: the issue of machine protection should be addressed with priority.
• Global Scheme. 1 cavity in IP4, Proof on LHC, good for 1 X-ing.• Semi-global; it may work!(JP Koutchouck)• Local scheme; 1 cavity per IP side. Maybe local doglegs needed.
– Early Separation Scheme could be an alternative (or a complement)• New Cryoplants in IP1 & IP5: for power AND to make independent Arc- IR:
2.8 kW @ 1.8 K scales as 5.2 kW @ 2 K (for 1 set of cold compressor)
26 April 2010
LHC Lumi Up @ 2nd CERN-MAC 13
HF Nb3Sn Quad• Nb3Sn is becoming a reality (first LQ long -3.6 m – quad 90 mm)• This year we expect a second LQ and a 1 m long - 120 mm aperture model• In 3 years: 4-6 m long magnet, 120 mm ap., G=180-200 T/m
26 April 2010
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TQS01a TQS02a TQS03a LQS01a
4.5 K ~3 K 1.9 K
Note: LQS01 & TQS02
use same strand design
(RRP 54/61)
200 T/m
LHC Lumi Up @ 2nd CERN-MAC 14
Crab Cavities
26 April 2010
qc
Elliptical 800 MHz not far from being designed. Require 400 mm beam-beam
400 MHz small cavity under conceptual study, they can (?) fit in 194 mm beam-beam. Required for final solution
Ref. : F. Zimmermann, Ed Ciapala
LHC Lumi Up @ 2nd CERN-MAC 15
Early separation schemepossible alternative/complement
26 April 2010
Nb3Sn at 8.5 T to have margin for heat deposition13 m from IP
Integration difficult but not impossible Leveling very easy…
Ref. : JP Koutchouk and G. Sterbini
LHC Lumi Up @ 2nd CERN-MAC 16
Lumi Plane 1st : the near term actions(in addition to collimation or Inj. Up)
1. Studies and R&D to prepare the upgrades– Pursuing of the needed R&D initiated in Phase 1. Finished in 2 years at
maximum.• 2 m long models of the Nb-Ti quads MQXC (2 y) • 1 prototype of nested corrector (rad-hard resin) (2y)• Complete study short cable MgB2 for Cold Powering (< 1 y)
– Matching sections and correctors improvements.– Pursuing a vigorous R&D on High Field/Gradient magnets– Launch Crab Cavity R&D, with test at SPS and finalized to insert a 800 MHz
cavity in IP4 as validation test on the 2014/15 horizon.
2. Cryoplants : first Point 4 for RF (on 2014/15 horizon) and then for the High luminosity triplets.
3. New SC links for removal of Power Converter from tunnel (surface, possibly). Decision on 2011 based on 200 m cable tested partly in vertical; installation on the 2014/16 horizon.
26 April 2010
LHC Lumi Up @ 2nd CERN-MAC 17
Resources P+M (MCHF + FTE)for R&D and consolid. for upgrades
26 April 2010
CONSOLIDATION and R&D for the upgrade Material in MCHF 2010 2011 2012 2013 2014 2015 2016 2017 2018 TOTMat 2.1 2.7 0.2 5FTE 6.5 8 1.5 16
Mat 0.5 3 4 7 6 5 1 27FTE 3 5 3 7 8 11 14 18 3 72
Mat 3 3.5 6 7.5 5 25FTE 11 11 15 18 12 67
Mat 0.5 2 3 3 3 2 14FTE 1 2 2 3 3 1 12
Mat 1.65 4.4 4.4 5.5 2.75 1.1 20FTE 3 3 6.5 6 3.5 2 24
0Mat 0.5 1 1.5 0.7 4FTE 2.5 4 4 3 14
TOT cons. R&D for upgr.Mat 7.75 14.1 15.1 19.7 14.75 10.1 6 5 1 94FTE 27 33 32 37 26.5 14 14 18 3 205
TOTAL Consolidation and necessary R&D to prepare the upgrade and exploit it
Phase 1 R&D completion (Models)
2 2-m long MQXC models, 1 cryoassembly, nested corrector MCXB, local link MgB2 (20 m, horiz.)
Modification to MSs, Stronger MCBY, MQT scheme, HWC 600 A, preapare for upgrade
HF SC development, Fresca2 dipole for test, Quad demonstrator, R&D 11 T twin dipole (cryocoll.)
Studies, test SPS, commiss. Prototype cavity in LHC-IP4 (either 800 or 400 MHz)
Crab Cavity R&D (with IP4 test)
Matching Sections Modifications
R&D HFM (Nb3Sn with protos)
R&D long ( 300 m) SC link for cold powering, with SM18 test of 200 m 60m high; MgB2 - HTS
Cryoplant 4.5 K in Point 4 to make RF independent
R&D and Demo SC link for cold powering
Cryoplant Point 4: contr.& commiss.
18
Lumi Plane 2nd : constructive projects For 2018: is 2020 more realistic ?
1. New Triplet and IR region. In 2013/14 decision on technology and of lay-out with all possible equipments. In the plan we assume that a strong US-LARP continue (and even reinforced).
– Either Nb3Sn if available before 2018 (not later than 2020). New cryo-plant s at 2K or even at 4.5 K.
– Or Nb-Ti as fall-back solution (cryo-plant at 1.8 K)
2. Crab Cavity (yes or not in 2014, too) ready on the same time scale of 2018. However, they could be installed later if infrastructure is prepared with the triplets.
– Early Separation scheme (today in shadow of crab, but…)
3. New DS dipole ( twin, 11 T – 11 m) to make room for the cryo-collimators. Available from 2015 (for points 2,7, 1, 5: we assume that for point 3 we are late and we need to displace magnets).
4. New cryo-plants for IP1 – IP5, decision among: 1.8 K, 2.0 K, 4.5 K see above.
26 April 2010 LHC Lumi Up @ 2nd CERN-MAC
LHC Lumi Up @ 2nd CERN-MAC 19
11 T – 11 m Twin Dipole for DS
26 April 2010
Shift in the magnet position requires to make room for collimators (red squares).
Alternative option based on stronger and shorter magnets (blue rectangles).
LHC Lumi Up @ 2nd CERN-MAC 20
P+M for main New Projects for upgr.Aimed at an installation date : 2018
26 April 2010
CONSTRUCTION PROJ. LUMI UP (excl. collimat.) Material in MCHF 2010 2011 2012 2013 2014 2015 2016 2017 2018 TOTNb-Ti based IR upgrade Mat 1.5 5 17 22 22.5 13.8 82
FTE 2 15 45 47 47 25 181Cryo for Nb-Ti capable to withstand L=6exp34 Cryoplant1.8 K@IP1-IP5 Mat 1.7 9.0 17.9 25.8 25.8 18.5 99
FTE 3 8 14 22 23 16 86
Nb3Sn based IR upgrade Mat 27 37 40.5 31.8 5 141FTE 57 59 59 37 8 220
Cryo for Nb3Sn capable of L= 6exp34 Cryoplant 2 K@IP1-IP5 Mat 1.7 4.5 14.6 22.4 22.4 17.4 83FTE 3 8 14 20 21 16 82
Sc link IP1-IP5 Mat 3 4 4 4 3 18FTE 4 5 5 5 4 23
Crab Cavity IP1-IP5 Mat 1 5 8 8 6 28FTE 1 6 10 12 10 39
5 x 11 T dipole in DS Mat 1 3 4 4 2 1 15FTE 2 5 7 7 5 3 29
TOT with Nb-Ti Mat 1.5 10.7 34.0 52.9 64.3 52.6 25.5 241FTE 2 24 64 79 91 69 29 358
TOT with Nb3Sn Mat 5.7 39.5 64.6 78.9 67.2 29.4 285FTE 9 76 91 101 79 37 393
11 T dipoles to make 4 m room in places where cryocollimators are needed (Point 2,7, 5, 1)
Total to arrrive to L ~ 4- 5 e34 with reliability (b*= 30 cm and ultimate intensity)
Total to arrrive to L 6 e34 with reliability (b* = 20 cm ultimate intensity)
New insertion with triplet, D1 and all like phase 1 in Nb-Ti
Design, Constr., comm. 10 cryomodules IP1-IP5 all inlcuded except cryogenics, Dogleg not included
Total for crab 400 MHz on 2 sides of IP1-IP5 , no dog-leg, cryoplant from the triplet.
SC link: removal PC to surface IP1-IP5 for IR magnets; it includes 8 MCH of C.E. Inst.2016/17
Material in MCHFSUMMARY CONSOL.+R&D+CONSTR. LUMI UP Option Nb-Ti Mat 7.75 14.1 16.6 30.38 48.7 63.02 70.26 57.56 26.48 335
FTE 27 33 34 61 90.5 93 105 87 32 563
SUMMARY CONSOL.+R&D+CONSTR. LUMI UP Option Nb3Sn Mat 7.75 14.1 15.1 25.38 54.23 74.66 84.9 72.2 30.36 379FTE 27 33 32 46 102.5 105 115 97 40 598
LHC Lumi Up @ 2nd CERN-MAC 21
Comments• Solid plane aimed to 5 1034 Lpeak AND year Ldt 150 fb-1 from 2020. Studies under way
to devise scenario with higher lumi.• Accounting with no overheads-contingency. • US contribution to NIT phase 1 for D1 (5 cold masses) and cold Powering is 30 M$ in US
accounting including overheads and contingency. – D1 : 30 FTE + 5 M$ approx. in CERN accounting, might be maintained (to be confirmed by June).
This figure has been added to cost of the New inner triplet to have the total cost.– Cold Power : 20 FTE + 3 M$ approx. in CERN accounting. This is not worth to continue because
will depend strongly on the actual scenario and lay-out of the upgrade (decision in 2014).• US and J are certainly a big part in a possible contribution for the IR: one can base, for a
High Gradient Inner triplet, that they can deliver as in-kind, the magnets (more than half of the hardware cost) or part of it.
• For the Nb3Sn Triplets the resources indicates the total needed. A program is already going on, so the additional money in 2010-13 is only a fraction of what is reported. CEA/CNRS is already committed for 4.5 MCHF + 2.8 FTE and its contribution might be increased of further 2-4 MCHF + 10-15 FTE, using the phase 1 resources.
• US and J can (should!) contribute to Crab cavities. Discussions just started (see today LARP meeting, where a possible Doe program is being discussed).
• Japan can also contribute to in-kind-contribution for Cryogenic upgrade.
26 April 2010
Appendix: (preliminary) shopping-list
The chromatic limit gives the dimension of the LHC Upgrade (b*, IT aperture, aperture of the matching section quad):a) At least 650A needed in the defocusing lattice sextupoles (for b*=20 cm). Sextupole limits to be clearly identified and 32 PC’s (600A) to be upgraded (changed).b) The correction of the off-momentum b-beating (and Q’’) requires prescribedbetatron phase advances from mid-arc to mid-arc and on the left/right side of the low-b insertions. Additional IR tunability needed and effectively obtained by re-cabling the arc tune shift quads (2 families instead of 1 per beam per plane and per sector).
The Matching Section (MS) aperture limitations pushed to the edge the quadrupole gradients of the low-b insertions (either to low field or max. field): Q5/Q6 0 T/m, Q7 200 T/m, some standalone MQT’s (@Q12 & Q13) 120 T/ma) Remove aperture bottle-neck in the MS (& TAN) Q5 assembly: MQY (70 mm) instead of MQM (56 mm) and MCBY type orbit corrector Q4 assembly: New 2-1 quadrupole type for Q4 (presently MQY) with ~ 85 mm coil aperture and new type (stronger) orbit correctors (presently MCBY). D2: New D2 (presently 80 mm coil ID but “only” 69 mm cold bore ID) with ~ 85 mm coil aperture 2-1 dipoles. New TAN (aperture to be defined depending on the D1-D2 distance).b) Readjust the MS layout (new azimuthal position for Q4 and Q5, Q6 a priori OK) to the length of the new IT to avoid pathological behavior (low gradient) at low b*. Typically moving Q4/Q5 towards the arcs by 15 m/10 m if the new IT is ~15 m longer.c) Re-commission the Dispersion Suppressor quadrupoles of IR1 and IR5 at higher current, in particular Q7 6KA (220 T/m @ 7TeV) as already done in SM18 but not in the tunnel (or new stronger Q7 if the above measurements are found to be insufficient.)
Courtesy of S. Fartouk
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