the large hadron- electron collider (lhec) · the large hadron-electron collider. 8 large...

The Large Hadron-electron Collider

(LHeC)Néstor Armesto

Departamento de Física de Partículas and IGFAEUniversidade de Santiago de Compostela

[email protected]

for the LHeC Study Grouphttp://cern.ch/lhec

1

NuPECC LRP2010 Town MeetingMadrid, May 31st 2010

mailto:[email protected]

mailto:[email protected]

http://cern.ch/lhec

http://cern.ch/lhec

Project:

The Large Hadron-electron Collider. 2

●LHeC@CERN → ep/eA experiment using p/A from the LHC:Ep=7 TeV, EA=(Z/A)Ep=2.75 TeV/nucleon for Pb.● New e+/e- accelerator: Ecm~1-2 TeV/nucleon (Ee=50-150 GeV).

● Requirements:* Luminosity~1033 cm-2s-1.

* Acceptance: 1-179 degrees(low-x ep/eA).* Tracking to 1 mrad.* EMCAL calibration to 0.l %.* HCAL calibration to 0.5 %.* Luminosity determination to 1 %.* Compatible with LHCoperation. x

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Proposed facilities:

LHeCFixed-target data:

NMC

E772

E139

E665

EMC

(Pb, b=0 fm)2sQ

perturbative

non-perturbative

(70 GeV - 2.5 TeV)e-Pb (LHeC)

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Physics goals:


● Proton structure to a few 10-20 m: Q2 lever arm.

● Precision QCD/EW physics.

● High-mass frontier (leptoquarks, excited fermions, contact interactions).

● Unambiguous access, in ep and eA, to a qualitatively novel regime of matter predicted by QCD.

● Substructure/parton dynamics inside nuclei with strong implications on QGP search.

The machine: Ring-Ring option


BYPASS

e-injector

The machine: Linac-Ring option


pulsed, racetrack

CW energy recovery

highest energy racetrack

● For ions, RR/LR: Luminosity per nucleon ~ 1-2×1032cm-2s-1,~ ep for

179o acceptance (low-x setup).

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HaC-Barrel

EmC-Barrel

HaC-insert-!-fwd

EmC-Endcap

EmC-Endcap-bwd

Central Tracking

Bwd TrackingFwd Tracking

HaC-insert-!-bwd

EmC-insert-!-bwd

EmC-insert-1/2

Solenoid

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Detector: low-x/eA setup


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Small-x physics:


● Novel regime of matter beyond the unitarity limit at small x and/or high A: saturation of partonic densities.● Two-pronged approach: ↓ x / ↑ A.● Prediction: semiclassical QCD at weak coupling (CGC).

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Nuclear parton densities (I):


● Large uncertainties in parton densities at low x in nuclei (no existing data).● LHeC data will substantially improve it.● Impact on the characterization of the hot medium in UrHIC through hard probes (cold nuclear effects).

Nuclear parton densities (II):


● ep/ed collisions at the LHeC would substantially improve our knowledge on the neutron pdf’s.● LHeC will test the relation between diffraction in ep and nuclear shadowing.

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Initial conditions for UrHIC:


● Azimuthal anisotropy in UrHIC (RHIC) points to lowviscosity/strong couplingof the produced medium.

● Initial conditions crucial for the collective behavior.

● eA offers a clean environment to check the ideas about particle production giving the initial condition, and thermalization.

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M.Tannenbaum,Rept.Prog.Phys65(2006)2005

Final state exploration:


● Low energy: need of hadronization inside → formation time, (pre-)hadronic absorption,...

● LHeC (νmax~105 GeV) will study the dynamics of hadronization

(partonic/hadronic eloss) by introducing a length of colored material to modify its pattern (length/nuclear size, chemical composition).

● High energy: partonic evolution altered in the nuclear medium, partonic energy loss.

Summary:


● LHeC: new facility at CERN for ep/eA collisions at Ecm~1-2 TeV under design.

● For nuclei, it will explore a new realm in their partonic structure.

● LHeC physics has strongimplications on UrHIC (thus complementary to pA@LHC).

● LHeC could be built in 10 years, depending on the LHC schedules and on us. http://cern.ch/lhec

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Proposed facilities:

LHeCFixed-target data:

NMC

E772

E139

E665

EMC

(Pb, b=0 fm)2sQ

perturbative

non-perturbative

(70 GeV - 2.5 TeV)e-Pb (LHeC)

http://cern.ch/lhec

http://cern.ch/lhec

Plans for the CDR:

13The Large Hadron-electron Collider.

Many thanks to Max Klein, Brian Cole, Paul Newman, Anna Stasto, Urs Wiedemann, Peter Kotska, David d’Enterria, Kari Eskola, Hannu Paukkunen, Carlos Salgado, Mark Strikman, Konrad Tywoniuk and all other collaborators in the preparation of the CDR!!!

The LHeC Study Grouphttp://cern.ch/lhec

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http://cern.ch/lhec

http://cern.ch/lhec

Backup: kinematics

The Large Hadron-electron Collider. 14Ax

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Salgado

● ep: access to the perturbative region below x ~ a few 10-5.

● eA: new realm.● pA@LHC will cover larger x, Q2.

Backup: eA collisions


● Ions are part of the LHC program: Pb, maybe Ar, Ca, O,...● RR/LR: Luminosity per nucleon ~ 1-2×1032cm-2s-1.

● Roughly the same luminosity per nucleon than in ep for a 1-179 degree acceptance (low-x/eA setup).

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the large hadron- electron collider (lhec) · the large hadron-electron collider. 8 large...

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