Pawel Nadel-TuronskiPawel Nadel-Turonski

Jefferson LabJefferson Lab

55thth Int'l Workshop on High-Energy Physics in the LHC Era Int'l Workshop on High-Energy Physics in the LHC Era

UTFSM, Valparaiso, Chile, December 16–20, 2013UTFSM, Valparaiso, Chile, December 16–20, 2013

The Electron-Ion Collider at JLab

for the MEIC groupfor the MEIC group

2

Outline

The Electron-Ion ColliderThe Electron-Ion Collider

Some physics highlightsSome physics highlights

Accelerator and detectorsAccelerator and detectors

3

EIC@JLab – physics program

• The EIC at JLab supports the full physics program for a generic EIC– INT report, white paper

• The JLab implementation of the EIC offers some unique accelerator and detector capabilities (focus of this talk)

4

EIC – consensus on global EIC requirements

• Stage I energy: √s = 20 – 70 GeV (variable)

• Stage II energy: √s up to about 150 GeV

• Polarized electron, nucleon, and light ion beams– Electron and nucleon polarization > 70%

– Transverse polarization at least for nucleons

• Ions from hydrogen to A > 200From base EIC requirements in the INT report

The EIC project is pursued jointly by BNL and JLab

• Luminosity reaching 1034 cm-2s-1

(EIC)(EIC)

((MMEEIICC))

5

EIC – staging at BNL and JLab

Stage I Stage I Stage II Stage II eRHIC @ BNLeRHIC @ BNL

MEIC / EIC @ JLabMEIC / EIC @ JLab √s = 13 – 7013 – 70 GeV

Ee = 3 – 12 GeV

Ep = 15 – 100 GeV

EPb

= up to 40 GeV/A

√s = 34 – 7134 – 71 GeV

Ee = 3 – 5 (10 ?) GeV

Ep = 100 – 255 GeV

EPb

= up to 100 GeV/A

√s = up to ~180180 GeV

Ee = up to ~30 GeV

Ep = up to 275 GeV

EPb

= up to 110 GeV/A

√s = up to ~140140 GeV

Ee = up to 20 GeV

Ep = up to at least 250 GeV

EPb

= up to at least 100 GeV/A

(EIC)(EIC)((MMEEIICC))

6

Already the first stage of an EIC gives access to sea quarks and gluons

Need polarization and good acceptance to detect spectators & fragments

An EIC aims to study the sea quark and gluon-dominated matter.

Stage I+II

Stage I

EIC staging

JLab12 GeV

7

Gluon dynamics plays a large role in proton spinGluon dynamics plays a large role in proton spin

3D structure of nucleons and nuclei is not trivial3D structure of nucleons and nuclei is not trivial

Why do quarks contribute so little (~30%) to proton spin?Why do quarks contribute so little (~30%) to proton spin?

How do gluons and quarks bind into 3D hadrons?How do gluons and quarks bind into 3D hadrons?

Gluons in nucleiGluons in nuclei (light and heavy) (light and heavy)

Does the gluon density saturate at small x?Does the gluon density saturate at small x?

Physics highlights from the EIC program

EIC stage II measurement?

EIC stage I measurement

Saturation-scale dependence on centrality of collision (from fragnent detection)?

8

Elastic form factors

Transverse spatial distributions

(Naively Fourier transform of Q2 or t)

Parton Distribution Functions

Longitudinal momentum distributions

Generalized Parton Distributions

A unified descriptions of partons

(quarks and gluons) in momentum

and impact parameter space

3D structure (also important part of JLab 12 GeV)

9

Imaging in coordinate and momentum space

k yk

x

-0.5

0.5

0.0

-0.5 0.0 0.5

bx [fm] Anselmino et al., 2009QCDSF/UKQCD

Coll., 2006

2+1 D picture in momentum space2+1 D picture in impact-parameter space

TMDsGPDs

• Accessed through Semi-InclusiveSemi-Inclusive DIS

• OAM through spin-orbit correlations?

• Accessed through exclusive processes

• Ji sum rule for nucleon spin

F1T

┴(x

) [

Siv

ers

fun

ctio

n]

quark density

Lattice QCD

10

Imaging in coordinate and momentum space

2+1 D picture in momentum space2+1 D picture in impact-parameter space

TMDsGPDs

Transverse gluon distribution from J/ψ production

J/ψγProjections from EIC white paper

11

Measure G - gluon polarization

Measure TMD and GPDs - orbital motion

Two complementary approaches to resolve proton spin puzzleTwo complementary approaches to resolve proton spin puzzle

The number ½ reflects both intrinsic parton properties and their interactions

The spin of the proton

½polarization orbit polarization orbit

quarks gluons

~ 0.35 small ?? ?

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(DVCS)(DVMP)

• DVCS on a transversely polarized target is sensitive to the GPD EGPD E

– GPD H GPD H can be measured through the beam spin asymmetry

– Opportunity to study spin-orbit correlations

x = 10-3

F. Sabatie

Ei(x, ξ, t) = κi(t) Hi(x, ξ, t)

Error bars shown only for κsea = +1.5

DVCS on proton

Model:

GPDs and angular momentum

1

1

),,(),,(2

1txEtxHxdxJ qqq

13

current data

w/ EIC data

Longitudinal spin – ΔG (gluon polarization)

JLab 12 GeV

• EIC stage I will greatly improve our understanding of ΔG– Stage II will further reduce the uncertainty

Q2 = 10 GeV2

M. Stratmann

Green:Green: RHIC spin, etc

Red:Red: EIC Stage I (MEIC or eRHIC)

Yellow:Yellow: EIC Stage II

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pT

q

h

*e

e

tproduction>RA

pT2 vs. Q2

Quark propagation in matter (hadronization)

tproduction< RA

pT

q*

e

e

h

• Broadening of pT distribution

Accardi, Dupre

large υ smaller υlarge υ

• Heavy flavors: B, D mesons, J/Ψ

• Hadron jets at s > 1000 GeV2

• Impact parameter dependence?Impact parameter dependence?

– Fragments and “wounded nucleons” can help understanding the path length

R. Dupre, POETIC, Valparaiso, Chile

15

Forward processes

Recoils in deep-exclusive (diffractive) processesRecoils in deep-exclusive (diffractive) processes

Partonic fragmentation in SIDISPartonic fragmentation in SIDIS

Nuclear fragmentsNuclear fragments

• Large t (pT) range desirable

– Small t: needs Roman pots to go close to the beam

– Large t: needs large acceptance magnets

• Spectator tagging with light ions

• Acceptance for complete final state (all fragments) in heavy-ion reactions?

– Could measure mass-, multiplicity-, and angular distributions and correlations

• Coherent nuclear processes

– Recoiling heavy ions are very difficult to detect

– Good acceptance at small pT extends the mass range

• Also decays of strange and charmed baryons

16

Opportunities with polarized light ions

Partonic structure of the neutron (including spin)Partonic structure of the neutron (including spin)

The bound nucleon in QCDThe bound nucleon in QCD

Collective quark/gluon fieldsCollective quark/gluon fields

• Spin/flavor decomposition of parton densities

• Modifications of nucleon's quark/gluon structure due to nuclear binding

– Off–shellness controlled by kinematics

• Coherent scattering probes the quark/gluon field of the entire nucleus

• Tensor-polarized structure function of deuterium identifies the QCD double-scattering contribution - insight into onset of gluon saturation

Experiment: requires excellent forward detection and spectator tagging

Theory: combines high-momentum-transfer processes and low-energy nuclear structure

FY13 LDRD funds approved at JLab for joint project (theory / experiment)

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Z. Kang

„If one could tag neutron, it typically leads to larger asymmetries“

Sivers asymmetryEIC kinematics

Z. Kang

D p

nn X

CLASCLAS + BoNuS

EIC

Spectator tagging with vector-polarized deuterium

Deuteron momentum distribution and comparison with fixed target

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New Hall

Add arc

Enhanced capabilitiesin existing Halls

Add 5 cryomodules

Add 5 cryomodules

20 cryomodules

20 cryomodules

Upgrade arc magnets and supplies

CHL upgrade

The completion of the 12 GeV Upgrade of CEBAF was ranked the highest priority in the 2007 NSAC Long Range Plan.

Scope of the project includes: • Doubling the accelerator beam energy• New experimental Hall and beamline• Upgrades to existing Experimental Halls

New C100 cryomodules in

linac tunnel

JLab 12 GeV upgrade – probing the valence quarks

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The EIC at Jefferson Lab

• Circumference of MEIC and CEBAF are similar (1.4 km)

• 12 GeV CEBAF is a full-energy e-injector

– Continuous injection as at SLAC (~50 nA)

– Parallel running with fixed target Halls A-D

• MEIC can store 20-100 GeV protons, or heavy ions up to 40 GeV/A.

• The stage II EIC will increase the energy to 250 GeV for protons and 20 GeV for electrons.

• Two high-luminosity, full-acceptance detectors

– IP2 could also host IP2 could also host sPHENIXsPHENIX.

Pre-booster

Ion linacMEIC

High-Energy Arc (Stage II)

e injection

IP2

IP1

Hall D

Halls A-C

C E

B A

F

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The MEIC magnets and tunnel (in CAD)

• The MEIC magnetic lattice design is complete

The background is an artist's impression

• Detector locations minimize synchrotron- and hadronic backgrounds

• Close to arc where ions exit• Far from arc where electrons exit

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MEIC – specific design goals

Spin control for all light ionsSpin control for all light ions

Full-acceptance detectorFull-acceptance detector

Minimized technical riskMinimized technical risk

• Figure-8 layoutFigure-8 layout

• Vector- and tensor polarized deuteriumVector- and tensor polarized deuterium

• Ring designed around detector requirementsRing designed around detector requirements

• Detection of all fragments – nuclear and partonicDetection of all fragments – nuclear and partonic

MEIC

EIC

MEIC

(arXiv:1209.0757)

Stable concept – detailed design report released August 2012

22

Dechirper Rechirper

Cooler Test Facility @ JLab FEL ERL

Regular electron cooling using a 55 MeV ERL

• Regular electron cooling is a well- established technique (e.g. at Fermilab)

• Recirculator tests are planned at the JLab Free-Electron Laser (FEL)

• A single-pass Energy-Recovery Linac (ERL) allows reaching higher electron energies and currents

• A recirculator ring is not needed for the ready-to-build MEIC cooling scheme, but would reduce the current requirements

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Science program demands highly polarized (>70%) light ions (p, D, 3He, Li, ...)

Figure-8 shape used for all ion booster and collider rings Spin precession in one arc is canceled by the other arc

No preferred periodic spin direction

Energy-independent spin tune

Simplified polarization control and preservation for all ion species

Needs only small magnetic fields (instead of Siberian Snakes) to control polarization at Ips

The electron ring has a figure-8 shape because it shares a tunnel with the ion ring

• Figure-8 ring is the only practical way to accelerate polarized deuteronspolarized deuterons

Pre-Booster

Large booster

Ion Collider Ring

MEIC – ion polarization in figure-8 ring

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far forwardfar forwardhadron detectionhadron detectionlow-Q2

electron detectionelectron detection large-apertureelectron quads

small-diameterelectron quads

central detectorcentral detector with endcaps

ion quads

50 mrad beam(crab) crossing angle

n,

ep

p

small anglesmall anglehadron detectionhadron detection

~60 mrad bend

(from GEANT4)

2 Tm 2 Tm dipoledipole

EndcapEndcap Ion quadrupolesIon quadrupoles

Electron quadrupolesElectron quadrupoles

1 m1 m11 m m

The MEIC full-acceptance detector concept

Forward hadron detection in three stages:Forward hadron detection in three stages:

1. Endcap with 50 mrad crossing angle1. Endcap with 50 mrad crossing angle

2. Small dipole covering angles up to a 2. Small dipole covering angles up to a few degreesfew degrees

3. Far-forward, up to one degree, for 3. Far-forward, up to one degree, for particles passing the accelerator quadsparticles passing the accelerator quads

IP FP

Roman potsRoman potsThin exit Thin exit windowswindows

Fixed Fixed trackers in trackers in vacuum?vacuum?

Trackers and “donut” calorimeterTrackers and “donut” calorimeter

RICH+

TORCH?

dual-solenoid in common cryostat4 m coil

barrel DIRC + TOF

EM

cal

ori

met

er

EM calorimeter

Tracking

EM

cal

ori

met

er

e/π

th

resh

old

Ch

eren

kov

25

dual-solenoid in common cryostat4 m coil

EM

cal

ori

met

er

e/π

th

resh

old

Ch

eren

kov RICH

+TORCH?

EM calorimeter

EM

cal

ori

met

er

barrel DIRC + TOF

Central detector options

(top view)

• Goal: two sufficiently different, complementary central detectors

– No need to for beam sharing at a ring-ring collider!

• First TOSCA model of 3T dual solenoid.

– Inspired by ILC 4th concept detector

• IP2 can be instrumented using an old magnet (CLEO or BaBar)

– Focus on hadronic calorimetry + small TPC central tracker

• IP1 (shown above): new 3T dual solenoid and large tracker

– Si-pixel disks and micropattern (GEM/micromega) forward trackers

– Low-mass cluster-counting He-filled DC (or micropattern) central tracker

2 m deep1 m deep

3 m

Co

il w

all

5 m3 m

Si-pixel vertex + disks

central tracker

forward tracker

forward tracker

Co

il w

all

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low-Q2 tagger

final focusing elements

e-

ions

The low-Q2 tagger – small angle electron detection

e-

ions

Electron beam aligned with solenoid axis

x e-

(top view)

• High-resolution detection of low-Q2 electrons using dipole chicane.

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89 T/m, 9.0 T, 1.2 m89 T/m, 9.0 T, 1.2 m 51 T/m, 9.0 T, 2.4 m51 T/m, 9.0 T, 2.4 m36 T/m, 7.0 T, 1.2 m36 T/m, 7.0 T, 1.2 m

Permanent magnetsPermanent magnets

34 T/m34 T/m 46 T/m46 T/m 38 T/m38 T/m2 x 15 T/m2 x 15 T/m e

5 T, 4 m dipole5 T, 4 m dipole

Ion quadrupoles: Ion quadrupoles: gradient, peak field, lengthgradient, peak field, length

2 T 2 T dipoledipole

Endcap detectorsEndcap detectors

Electron quadrupolesElectron quadrupoles

TrackingTracking CalorimetryCalorimetry

1 m1 m1 m1 m

• Large crossing angle (50 mrad)– Moves spot of poor resolution along solenoid axis into the periphery

– Minimizes shadow from electron FFQs

Crossing angle

• Dipole before quadrupoles further improves resolution in the few-degree range

Hadron detection between endcap and ion quads

• Low-gradient quadrupoles allow large apertures for detection of all ion fragments

– Peak field = quad gradient x aperture radius

7 m from IP to first ion quad7 m from IP to first ion quad

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ions

Hadron detection after the ion quads

e

p

(n, γ)20 Tm dipole (in)

2 Tm dipole (out)

solenoid

Roman pots at Roman pots at focal pointfocal point

Thin exit Thin exit windowswindows

Aperture-free drift spaceAperture-free drift spaceZDCZDC

S-shaped dipole configuration S-shaped dipole configuration optimizes acceptance for neutralsoptimizes acceptance for neutrals

50 mrad crossing angle

• Transport optimizes acceptance for both neutrals and charged particles.

• Lots of space for Zero-Degree calorimeter (ZDC) on the outside of the ring

– Hcal and EMcal

• Hcal: RD52 „DREAM“ or particle flow type.

29

1. Good acceptance for ion fragments1. Good acceptance for ion fragments (rigidity different from (rigidity different from beam)beam)

2. Good acceptance for low-p2. Good acceptance for low-pTT recoil baryons recoil baryons (rigidity similar to (rigidity similar to

beam)beam)

3. Good momentum- and angular resolution3. Good momentum- and angular resolution

• Large downstream magnet apertures• Small downstream magnet gradients (realistic peak fields)

• Roman pots not needed

• Small beam size at second focus (to get close to the beam)• Large dispersion (to separate scattered particles from the beam)

• Roman pots important

• Large dispersion (but with D = D' = 0 at IP)• Long, instrumented, magnet-free drift space

4. Sufficient separation between beam lines (~1 m)4. Sufficient separation between beam lines (~1 m)

Ultra-forward hadron detection – requirements

D n

Xp

DVCS on the proton

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Asymmetric ion optics

• Beam angular spread is also proportional to √(ε/β*) → good ion beam cooling essential

Ions x

IP FP

βx* = 10-20 cm

βy* = 2 cm

D* = D'* = 0

βFP < 1 m

DFP ~ 1 m

• β* x/y asymmetry allows a high luminosity with relatively small βmax

• Only dispersion component (D) generated after the IP aids detection, but dispersion slope (D') at IP adds to the beam angular spread (Dp/p)

• 7 m from IP to first downstream ion quad

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Δp/p = -0.5 Δp/p = 0.0 Δp/p = 0.5

Far-forward detection of charged fragments

(protons rich fragments)

(exclusive / diffractive recoil protons)

(tritons from N=Z nuclei)(spectator protons from deuterium)

(neutron rich fragments)

• For light ions focus the mass/charge ratio of fragments is usually very different from the beam

• For heavy ions one needs both good acceptance and momentum resolution

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6 T max

9 T max

horizontal plane vertical plane50 mr crossing angle in ion beam

Forward acceptance vs.magnetic rigidity

RedRed: Detection before ion quadrupoles

BlueBlue: Detection after ion quadrupoles

magnetic rigidity relative to beam

acc

eta

nce

(d

eg

ree

s)

• The angle is the original scattering angle at the IP

Fragment acceptance vs quadrupole peak field

• Q3P can be weaker– “9 T” is actually 9, 9, and 7 Tesla

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e

p

n, γ

Far-forward hadron detection summary

20 Tm dipole2 Tm dipole

solenoid

• Excellent acceptance for all ion fragmentsall ion fragments

• NeutralsNeutrals detected in a 25 mrad (total) cone down to zero degreesdown to zero degrees

– Space for large (> 1 m diameter) Hcal + Emcal

• Recoil baryonRecoil baryon acceptance:

– up to 99.5%99.5% of beam energy for all anglesall angles

– down to at least 2-3 mrad2-3 mrad for all momentaall momenta

– full acceptance for x > 0.005

• 15 MeV resolution for a 50 GeV/A tagged deuteron beam

• Resolution limited only by beam

– Longitudinal (dp/p): 3x103x10-4-4

– Angular (all φ): 0.2 mrad0.2 mrad

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Floor space in the new test lab at JLab – DVCS solenoid shown.

CLAS DVCS solenoid with 9 inch boreCLAS FROST solenoid with 5 inch bore

Generic detector R&D for an EIC – example• R&D program not site specific

– Coordinated by Tom Ludlam (BNL)

• As part of the program, a new, permanent EIC facility for sensor tests in high magnetic fields is being set up at Jefferson Lab

– Two 5T magnets provided by JLab

• Tests will include MCP-PMTs with small pore size (2-6 μm), SiPMs and LAPPDs

Non-magnetic dark box with pulsed LED for the DVCS solenoid – note the GlueX SiPM

(Hamamatsu S11064-050P(X))

35

2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025

12 GeV Upgrade

FRIB

EIC Physics Case

NSAC LRP

EIC CD0

EIC Machine Design/R&D

EIC CD1Downselelect

EIC CD2/CD3

EIC Construction

Assumes endorsement for an EIC at the next NSAC Long Range PlanAssumes relevant accelerator R&D for down-select process done around 2016

EIC timeline

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Summary

• JLab or BNL implementations possible– Agreement on global parameters

– Collaboration on detector R&D

The EIC is the next-generation US QCD facilityThe EIC is the next-generation US QCD facility

The EIC at JLab offers some unique capabilitiesThe EIC at JLab offers some unique capabilities

Complementarity with the LHC/LHeCComplementarity with the LHC/LHeC

• The MEIC will cover all kinematics between JLab 12 GeV and the LHeC

• Vector- and tensor polarized deuterium

• Excellent detection of recoil baryons, spectators, and target fragments

– Full acceptance, high resolution

37

Backup

38

Electron source for electron cooling

• MEIC high-energy electron cooling requires a source of ~2 nC few-cm long electron bunches with a repetition rate of ~15 MHz and an average current of ~30 mA.

• Slava suggested using a short-pulse high-bunch-charge high-repetition-rate magnetized DC gun with subsequent bunch compression.

• Such a scheme, with the exception of beam magnetization, seem to exist at BINP and has been used as an electron source for NovoFEL since 2003.

• A DC gun with a thermionic metal-oxide gridded cathode has the following parameters:

• All gun (and injector) parameters seem consistent with the electron cooler requirements.

• A thermionic RF gun is being developed at BINP to replace the DC gun. The reasons for upgrade are not clear but, perhaps, involve improved cathode lifetime and higher current.

• Beam tests of the RF gun started recently with encouraging results.

Electron energy 300 kVBunch charge ~1.5-2 nCMaximum peak current ~1.8 AMaximum average current ~30-45 mAMaximum bunch repetition rate 22.5 MHzBunch length ~1.3 nsNormalized emittance 10 mmmrad

39

Electron polarization – continuous injection

• Polarization at t+Δt

0))(1( PN

Nt

t

PP

N

NP t

ttt

10 )1(

injdk

ringrevequ I

ITPP

• Equilibrium Polarization

Lost or Extracted P0

(>Pt)Pt

• Note that:– Polarization lifetime at 5 GeV is 1 or 3 hours depending on helicity

(Sokolov-Ternov)– 50-100 nA beam injected from CEBAF can maintain polarization close

to its initial value of 80% indefinitely for any elevtron beam energy.

Equilibrium Polarization vs. Average Injected Current

40

Deuteron polarization in figure-8 ring

• Beam injected longitudinally polarized, accelerated and then desired spin orientation adjusted

(B||L)1,2 (Tm) vs. p (GeV/c)

longitudinal polarization

radial polarization

y

yz

sin

)sin(1

yz

sin

sin2

Gy

is the spin rotation angle between the solenoids

is the orbit rotation angle between the solenoids is the angle between the polarization and velocity directions

21, zz are the spin rotation angles in the solenoids

B

LBG i

zi||1

41

Proton polarization in figure-8 ring

Last two arc dipoles

(BL)i (Tm) vs. p (GeV/c)

longitudinal polarization radial polarization(BxL)1

(BxL)2

(BxL)3

(BxL)4

42

Ion acceptance and resolution at the focal point

±10σ beam size at 60 GeV

• Large deflections allow precise tracking over long distances with cheaper detectors

– Particles with deflections > 1 m at the FP will be detected closer to the dipole

• Detection past the focal point is also possible, but with acceptance restrictions

43