Large Hadron electron Collider - LHeC

Frank Zimmermann

UPHUK-4, Bodrum, 31 August 2010

4. Uluslararası Katılımlı Parçacık

Hızlandırıcıları ve Uygulamaları Kongresi (UPHUK4) 30 Ağustos-1 Eylül 2010

outline• physics motivation • target parameters• Linac-Ring & Ring-Ring options• e+ source options• p beam parameters• IR design• e- beam parameters, e- RLA/ERL layouts • LHeC-CLIC• high-energy ERL option• tentative schedule, conclusions

LHeC – Large Hadron electron Collidermotivation:• rich physics program: e-q physics at TeV energies precision QCD & electroweak physics boosting precision and range of LHC physics results beyond the Standard Model high density matter: low x and eA, & also A collisions

Tevatron/LEP/HERA (Fermiscale) LHC/LC/LHeC (Terascale)

100 fold increase in luminosity, in Q2 and 1/x w.r.t. HERA

status: •CERN-ECFA-NuPECC workshops (2008, 2009, 2010: 28.-30.October)

•Conceptual Design Report in print by spring 2011

distance scales resolved in lepton-hadron scattering experiments since 1950s, and some of the new physics revealed

energies and luminosities of existing and proposed future lepton-proton scattering facilitiese- energy ~60-140 GeV luminosity ~1033 cm-2s-1

LHeC - more physics motivation>5x HERA c.m. energy>>10x HERA luminosity

Max Klein & Paul Newman, CERN Courier April 2009

Max Klein & Paul Newman, CERN Courier April 2009

kinematic planein Bjorken-x and resolving power Q2, showing the coverage of fixed target experiments, HERA and LHeC

>> 10x

particle physicists request both e-p &e+p collisions;lepton polarization is also “very much desired”

Max Klein & Paul Newman, CERN Courier April 2009

LHeC – several optionsRR LHeC:new ring in LHC tunnel,with bypassesaround experiments

RR LHeCe-/e+ injector10 GeV,10 min. filling time

LR LHeC:recirculatinglinac withenergy recovery,or straightlinac

this talk will focus on “linac” options

least interference with LHC infrastructure

compatible with LHC energy upgrade

upgrade potential to higher energy or to LC

lots of synergies with CLIC, ILC and SPL

however LR LHeC is not the baseline or not yet

LHeC-RR & LHC interferences„About 350 places to be avoided for e-magnets.

Some areas very difficult. Solutions will be looked for, once a solution for the other ~350 obstacles has been found.

Note: The experiments 1 and 5 are passed on the outside. That increases the overall length.[beware of Hirata-Keil beam-beam resonances!]

We have to cross the transport region to compensate the overlength. This is almost impossible, because it would make any accelerator repair even more difficult.“

K.-H. Mess, February ‘10

→ dense net of resonances in tune space if circumferences are slightly different→ spontaneous beam separation

Hirata-Keil resonances: beam-beam resonances for circumference ratio K+/K-≠1

K. HirataandE. Keil,1990;

compare alsooverlapknockoutresonancesat CERN ISR(S. Myers)

Large Hadron electron Collider -Linac-Ring options

J. Osborne

TOBB ETU

KEK

L-R LHeC – collaborating institutes

LHeC LR design contributorsS. Bettoni, C. Bracco, O. Brüning, H. Burkhardt, E. Ciapala,

B. Goddard, F. Haug, B. Holzer, B. Jeanneret, J. Jowett, J. Osborne, L. Rinolfi, S. Russenschuck, D. Schulte, H. Thiesen,

R. Tomas, F. Zimmermann, CERN, Switzerland;

C. Adolphsen, M. Sullivan, Y.-P. Sun, SLAC, USA;

A.K. Ciftci, R. Ciftci, K. Zengin, Ankara U.,Turkey;

H. Aksakal, Nigde U.,T.; E. Eroglu, I. Tapan, Uludag U., Turkey;

T. Omori, J. Urakawa, KEK, Japan ; S. Sultansoy, TOBB, Turkey;

J. Dainton, M. Klein, Liverpool U., UK; A.Variola, LAL, France;

R. Appleby, S. Chattopadhyay, M. Korostelev, Cockcroft Inst., UK;

A. Polini, INFN Bologna, Italy; E. Paoloni, INFN Pisa, Italy;

P. Kostka, U. Schneekloth, DESY, Germany;

R. Calaga, V. Litvinenko, V. Yakimenko, BNL, USA;

A. Eide, NTNU, Norway ; A. Bogacz, JLAB, USA

more are welcome!

performance targetse- energy ≥60 GeVluminosity ~1033 cm-2s-1

total electrical power for e-: 100 MWe+p collisions with similar luminositysimultaneous with LHC pp physicse-/e+ polarizationdetector acceptance down to 1o

getting all this at the same time is very challenging

SLC CLIC

(3 TeV)

ILC

(RDR)

LHeC

Energy 1.19 GeV 2.86 GeV 5 GeV 60 GeV

e+/ bunch at IP 40 x 109 3.72x109 20 x 109 2x109

e+/ bunch before DR inj. 50 x 109 7.6x109 30 x 109 N/A

Bunches / macropulse 1 312 2625 N/A

Macropulse repet. rate 120 50 5 CW

Bunches / second 120 15600 13125 20x106

e+ / second 0.06 x 1014 1.1 x 1014 3.9 x 1014 400 x 1014

Flux of e+

X 18X 65

X 6666

quite a challenge!

L. Rinolfi, May 2010

e+ source options

• Compton ring

• Compton ERL

• Compton linac

• undulator based source

• e- beam on liquid metal-jet target

• e+ recycling

Compton Ring and Compton ERL (ILC)

T. Omori, L. Rinolfi,J. Urakawa et al

Compton Linac for e+ source

4 GeV

N / Ne- = 1 (demonstrated at BNL)

Ne+ / N = 0.02 (expected)

i.e. 50 gammas to generate 1 e+

312 pulses

~5 ns

With 5 nC / e- bunch and 10 Compton IP's

=> 1 nC / e+ bunch

Data for CLIC:

Ne+ = 6.4 x 109 / bunch ~ 1 nC

Ne- = 0.32 x 1012 / bunch ~ 50 nC

For LHeC, one would need to increase the number of targets/capture sections working in parallel in order to reach the requested intensity. => Cost and reliability issues T. Omori, L. Rinolfi,

J. Urakawa et al

LHC

e- Linacspent e-

e+ pre-Linac

IP 1

e+

p+

Target

LHeC e+ source based on undulator

Undulator

e-

e+ Linac

L. Rinolfi et al

- CERN “Merit” (liquid Hq droplet target): possibility to handle MW beam.- Tokyo University S-band gun generating 3nC every 2.8ns for 100 bunches and plan to go up to 1000 bunches

LHeC proposal: send ~1 MW average power e- beam on liquid target ~100 Hz, ~1 s trains, 1 A average over macro pulse, 100 A average current; e+/e- yield > 1 with small transverse emittance

total wall plug power for e+ source ~3-5MW

cost estimate) ~50M$

concern: stability of “droplet” during macropulse

high-power e- beam on liquid-metal targetV. Yakimenko, June 2010

1 MW e- beam

liquid metal target

e+

hgepp

pb HIN

eL

*

, 1

4

1

how do we get 1033 cm-2s-1?

luminosity of LR collider:

take highest protonbeam brightness permittedby LHeC management(“ultimate” LHC values)

assume smallest conceivableproton * function: - reduced l* (23 m → 10 m)- squeeze only one p beam- new magnet technology Nb3Sn

maximize geometricoverlap factor- head-on collision- small e- emittance

(round beams)

average e- current !

proton beam brightness Nb,p/p

management decision proton bunch spacing(which multiple of 25 ns)is irrelevant for LHeC!

proton round-beam IR optics for ultra-low *

R. Tomas

l*=10 m

extended e- final-focus optics byKahraman Zengin,Ankara U.

S. Fartoukh

arc increased by a factor of 2 or 8 in s45/56/81/12depending on the * aspect ratio in IP1 and IP5

squeezed optics: *

x/y = 7.5/30 cm (flat beam) alternated in IR1&5

new flat p-p HL-LHC optics w low * & l*=23 m

this flat-beam optics is alternative for LHeC

geometric reduction factor

geometric loss factor Hhg vs. crossing angle

LHeC working point

S

zzeH

z

hg

erfc2

C. AdolphsenH. BraunF. Zimmermann

p*=10 cm

(round beams)

interaction region (2008)R. Tomas, F.Z.

small e- emittance → relaxed e* → Le

* > Lp*, can&must profit from

↓p* ; single pass & low e-divergence → parasitic collisions of little

concern; → head-on e-p collision realized by long dipoles

or return loop

IR layout w. head-on collision

beam envelopes of 10 (electrons) [solid blue] or 11(protons) [solid green], the same envelopes with an additional constant margin of 10 mm [dashed], the synchrotron-radiation fan [orange], and the approximate location of the magnet coil between incoming protons and outgoing electron beam [black]

detector integrated dipole: field ~0.45 Tcritical photon energy ~ 1 MeV

average SR power = 87 kW8x1010 / bunch passage

is the SR

acceptable

for the

detector?

prize questions

can we shield the SC proton quadrupole from MeV synchrotron radiation?- “this SR is very difficult to shield”

K.-H. Mess, LHeC Divonne 2008- studies by Husnu Aksakal (2009) and

Emre Eroglu (2010)

can we reduce back-scattering into the detector to an acceptable level?- studies by Kenan and Rena Ciftci (2010)

SR shielding - FLUKA simulationbeam energy [GeV] 20 50 60 100 140

dipole field [T] 0.6 0.2 0.35 0.5 0.65

offset at LHC triplet [cm] 45 6 8.75 7.5 7

distance IP& p-triplet [m] 10

lead shieldingin front of triplet

vacuumdipole

exampleFLUKAresults[GeV/cm3]

SR code (linkedto FLUKA) calculates #SR photos per m,per energy bin

Husnu Aksakal, Nigde U., 2009

30 cm shielding is enough

LEAD (Pb)LEAD (Pb)

EEnergy deposition in nergy deposition in llead targetead target..

Max. value is 0.152 GeV/cmMax. value is 0.152 GeV/cm33//

For For 25 cm 25 cm of lof leadead no SR photon penetrates through the target. no SR photon penetrates through the target.

Emre Eroglu,Uludag U., 2010

FLUKA simulation

again 30 cm shielding is enough

bback scattering ack scattering of eof e-- and and ee++ from from llead targetead target

Max. energy is about Max. energy is about 0.103 Gev/cm0.103 Gev/cm33// for for electron (up), and about electron (up), and about 0.075 GeV/cm0.075 GeV/cm33// for for positron (down).positron (down).

Emre Eroglu,Uludag U., 2010

FLUKA simulations

e-

e+

BBack scattering ack scattering of of ’s ’s from from llead ead targettarget..

Max. energy is about 0.242 GeV/cmMax. energy is about 0.242 GeV/cm33// for photon for photon

LEAD (Pb)LEAD (Pb) Emre Eroglu,Uludag U., 2010

reflection of ’s by mirrors

Surface of the magnet-coil protection shield should besloped to reduce power density. Acceptable: ~10-20 W/mm2.

Proposal: introduce mirrors with a shallow grazingangle to reflect part of the photons into electron beamchannel or special SR extraction holes

Kenan & Rena Ciftci,Ankara U., 2010

“supercon” type magnet

p

e-

d~8.7 cm

S. Russenschuckgradient ~250 T/m Nb-Ti ~310 T/m Nb3Sn

“mirror” half quadrupole magnet

p

e-

d~6.3 cm

S. Russenschuckgradient ~145 T/m Nb-Ti ~175 T/m Nb3Sn

detector integrated dipole

SCsolenoidcoil

SC coilsplitandtilted

B

BStephan Russenschuck, Simona Bettoni, Eugenio Paoloni

IP

how about 2nd LHC proton beam?

2nd beam must be transported across LHeC IR

two possibilities:

(1) common IR vacuum chamber; second beam unsqueezed

(2) detector with a bypass hole (c.f. Tevatron D0)

we did what we could on p side

how about e-? e- emittances and * not critical

(protons are big, ~7m!)most important parameter:average beam current

in addition: bunch structureand polarization

targetluminosity

we need about 6 mA

CLIC design current ~ 0.01 mA (factor 600 missing) lowering voltage, raise bunch charge & rep rate → 0.06 mA (NIMA 2007)

CLIC drive beamILC design current ~ 0.05 mA (factor ~100 missing)

SC linacs can provide more average current at lower energy (& lower gradient) e.g. by increasing the duty factor 10-100 times,

or even running cw

example design average currents:CERN HP-SPL: ~2.5 mA (50 Hz)

Cornell ERL ~100 mA (cw)eRHIC ERL ~ 50 mA at 20 GeV (cw)

LHeC ERL needs 6 mA at 60 GeV

LHeC ERL site power

main contributions:RF power dissipation +RF power to compensate ERL inefficiency

Cryo power for SC linac (RF gradient)

SR energy losses in return arcs (radius)

BDEgg

EAPcr

rfwallbeamrf

ERLbeamrf

PCDEgP

1

4EPsr

g: gradientE: final energyD: duty factor

A, B and C:coefficients

: bending radius

one more ingredient!

1.67 km0.34 km

30-GeV linac

LHC p

LHC p

1.0 km

2.0 km

10-GeV linac

10-GeV linacp-60 erl

LHC p

70-GeV linac

3.9 km

2.0 km

p-140

injectordump

injector dump

dumpinjector

IP

IP

IP

140-GeV linac

p-140’

injector dump

IP7.8 km

LHeC –Linac-Ring configurations

highluminosity

highenergy

“least expensive"

LHeC – general parameterse- beam RR LR ERL LR “p-140”e- energy at IP[GeV] 60 60 140luminosity [1032 cm-2s-1] 17.1 10.1 0.44polarization [%] 5 - 40 90 90bunch population [109] 26 2.0 1.6e- bunch length [m] 10000 300 300bunch interval [ns] 25 50 50transv. emit. x,y [mm] 0.58, 0.29 0.05 0.1

rms IP beam size x,y [m] 30, 16 7 7

e- IP beta funct. *x,y [m] 0.18, 0.10 0.12 0.14

full crossing angle [mrad] 0.93 0 0geometric reduction Hhg 0.77 0.91 0.94

repetition rate [Hz] N/A N/A 10beam pulse length [ms] N/A N/A 5ER efficiency N/A 94% N/Aaverage current [mA] 131 6.6 0.27tot. wall plug power[MW] 100 100 100

p- beam RR LRbunch pop. [1011] 1.7 1.7tr.emit.x,y [m] 3.75 3.75

spot size x,y [m] 30, 16 7

*x,y [m] 1.8,0.5 0.1$

bunch spacing [ns] 25 25

$ smaller LR p-* value than for nominal LHC (0.55 m):

- reduced l* (23 → 10 m)- only one p beam squeezed- new IR quads as for HL-LHC

B. Holzer,M. Klein,F. Zimmermann

example (old) RLA optics for 4-pass ERL optionw. 500 MeV injection energy (=dump energy)

0.5→ 31.25 → 60 → 31.25 → 0.5 GeV

LHeC question:feeding groupsof linacquadrupolesby one power converter?

or no quads?! Vladimir Litivinenko

Hugues Thiesen

new optics under development by Alex Bogacz (JLAB)

Anders Eide

W. Meng et alPAC’09

common vacuum chamber for eRHIC return loop with several layers of small-gap magnets, profiting from small e- emittance

LHeC questions:same power converterfeeding magnets for several loops with different number of coils or separate power converter for each loop?strength of dipoles and quad’s tapered to localbeam energy (SR)?

details of return loop design

Hugues Thiesen

Relative emittance for three final beam energies (60 GeV, 100 GeV and 140 GeV); here test initial emittance is 2 μm. For E = 140 GeV, the absolute normalized emittance growth is roughly 50 μm, which was confirmed byother simulation studies with higher start emittance & by analytical estimates

SR & chromatic emittance growth

Y.-P. Sun

=100 mat 140 GeVand 50 m at60 GeV areconservativevalues

SR emittance growth:few % at 60 GeV, &100% at 140 GeV

SR emittance growth OK!

ERL collective effects

multi-beam wakes & beam break upmodified PLACET code (D. Schulte)

ion accumulation and ion-driven instabilitiesneeds gaps and/or clearing electrodes

electron-cloud instability for e+ beamsimulations planned (G. Rumolo)

beam dump

without energy recovery we will have to dump a ~50 MW e- beam

= 2-3 x maximum ILC beam power !

CERN dump experts: feasible ! (Brennan Goddard, Chiara Bracco)

future work

• updated/new optics for ERL

• study of ERL collective effects

• detector-integrated dipole design

• flat-beam IR optics

• conclusion on IR synchrotron radiation

• e±-A/-p/-A options, esp. IR layouts & laser

• e+ source baseline solution

• …

hgepp

pb HIN

eL

*

, 1

4

1

Higher performance w CLIC?

luminosity of LR collider:

raising p bunch population

(round beams)

allows reducing average e- current

higher luminosities with CLIC?extreme possibility: dramatically increase Nb,p

by putting all protons in single bunch of length ≤ CLIC train length: “proton superbunch”(D. Schulte, F. Zimmermann, CLIC Notes 589 & 608)

collision region then extends over ≤ 23 mthis would bring luminosity factor ~3000!

†unfortunately ATLAS and CMS rejected superbunches in a strongly worded joint official statement at CARE HHH-2004

highest-energy LHeC ERL option

High luminosity LHeC with nearly 100% energy efficient ERL.The main high-energy e- beam propagates from left to right.In the 1st linac it gains ~150 GeV (N=15), collides with the hadron beam and is then decelerated in the second linac.Such ERL could push LHeC luminosity to 1035 cm-2s-1 level.

V. Litvinenko, 2nd LHeC workshopDivonne 2009

this looks a lot like CLIC 2-beam technology

high energy e- beam is not bent; could be converted into LC?

LHeC-LR & CLIC synergies

original hope was to later extend linac & convert into LC (staged LC construction, with “cheap” starting point)

however, this may not be possible as the CLIC or ILC tunnels are positioned & oriented differently (J. Osborne)

many LHeC LR subsystems and technologies are similar to those of ILC or CLIC

linac, RF power source, e- injector, e+ source, final focus, highest-energy option (!), but most requirements are more relaxed (emittance, spot size); gain experience! equipment could be reused for CLIC or ILC

many of the same people work on LC and LR LHeC

LHeC – possible schedule2020-21: installation of (ring or linac) LHeC,

during HL-LHC upgrade shutdown

2021-30: ~10 years of operation with LHC [p/A] colliding with Ee ≈ 60 GeV [e-/e+]: ~100 fb-1

after 2030: possible extension to high Ee LHeC, during HE-LHC upgrade shutdown and long term operation with 16.5 TeV p colliding with e.g. Ee = 140 GeV [e-/e+]

conclusions• ERL with 2x10 GeV SC linac proposed for high-

luminosity 60-GeV Linac-Ring LHeC

• possibility of extension to >100 GeV e- energies

• good progress with linac & IR designs

• many contributions from Turkish universities & TAC

• synergies with SPL, eRHIC, EIC, CLIC, ESS, …

• LHeC CDR due by coming October

thank you!