Design Status of ELIC

G. A. Krafft for ELIC Design Team and Medium Energy Collider Design Team

Jefferson Lab Physics Seminar Feb 6, 2009 Thomas Jefferson National Accelerator Facility Page 1

Outline

   

ELIC: An Electron-Ion Collider at CEBAF Basic parameters List of recent developments/specs Some R&D Issues

 

Electron Cooling Crab Crossing



Medium Energy Colliders and Staging



Summary Thomas Jefferson National Accelerator Facility Page 2

ELIC Study Group & Collaborators

A. Afanasev, A. Bogacz, P. Brindza, A. Bruell, L. Cardman, Y. Chao, S. Chattopadhyay, E. Chudakov, P. Degtiarenko, J. Delayen, Ya. Derbenev, R. Ent, P. Evtushenko, A. Freyberger, D. Gaskell, J. Grames, A. Hutton, R. Kazimi, G. A. Krafft, R. Li, L. Merminga, J. Musson, M. Poelker, R. Rimmer, Chaivat Tengsirivattana, A. Thomas, H. Wang, C. Weiss, B. Wojtsekhowski, B. Yunn, Y. Zhang Jefferson Laboratory W. Fischer, C. Montag - Brookhaven National Laboratory V. Danilov - Oak Ridge National Laboratory V. Dudnikov - Brookhaven Technology Group P. Ostroumov - Argonne National Laboratory V. Derenchuk - Indiana University Cyclotron Facility A. Belov - Institute of Nuclear Research, Moscow, Russia V. Shemelin - Cornell University Thomas Jefferson National Accelerator Facility Page 3

Jefferson Lab Now

Thomas Jefferson National Accelerator Facility Page 4

RHIC Lab Now

Thomas Jefferson National Accelerator Facility Page 5

ELIC Design Goals



Energy

•

Center-of-mass energy between 20 GeV and 90 GeV

•

energy asymmetry of ~ 10,



3 GeV electron on 30 GeV proton/15 GeV/n ion up to 10 GeV electron on 250 GeV proton/100 GeV/n ion



Luminosity

•

10 33 up to 10 35 cm -2 s -1 per interaction point



Ion Species

•

Polarized H, D, 3 He, possibly Li

•

Up to heavy ion A = 208, fully stripped



Polarization

•

Longitudinal polarization at the IP for both beams

•

Transverse polarization of ions

•

Spin-flip of both beams

•

All polarizations >70% desirable



Positron Beam

desirable

Thomas Jefferson National Accelerator Facility Page 6

Evolution of the Principal Scheme

 Energy Recovery Linac-Storage-Ring (ERL-R)  ERL with Circulator Ring – Storage Ring (CR-R) 

Back to Ring-Ring (R-R) – by taking CEBAF advantage as full energy polarized injector

 Challenge: high current polarized electron source • ERL-Ring: 2.5 A • Circulator ring: 20 mA • State-of-art: 0.1 mA 

12 GeV CEBAF Upgrade polarized source/injector already meets beam requirement of ring-ring design



CEBAF-based R-R design still preserves high luminosity, high polarization (+polarized positrons…) Thomas Jefferson National Accelerator Facility Page 7

ELIC Conceptual Design

Green-field design of ion complex directly aimed at full exploitation of science program.

Thomas Jefferson National Accelerator Facility Page 8 12 GeV CEBAF Upgrade

ELIC Ring-Ring Design Features



Unprecedented high luminosity



Enabled by short ion bunches, low β*, high rep. rate



Large synchrotron tune



Require crab crossing



Electron cooling is an essential part of ELIC



Four IPs (detectors) for high science productivity



“Figure-8” ion and lepton storage rings



Ensure spin preservation and ease of spin manipulation



No spin sensitivity to energy for all species. Thomas Jefferson National Accelerator Facility Page 9

Achieving High Luminosity of ELIC

ELIC design luminosity L~ 2.6 x 10 34 cm -2 sec -1 (150 GeV protons x 7 GeV electrons) ELIC luminosity Concepts

• • • •

High bunch collision frequency (f=0.5 GHz) Short ion bunches ( σ z ~ 5 mm) Super strong final focusing ( β* ~ 5 mm) Large beam-beam parameters (0.01/0.086 per IP, 0.025/0.1 largest achieved)

• •

Need High energy electron cooling of ion beams Need crab crossing

• •

Large synchrotron tunes to suppress synchro-betatron resonances Equidistant phase advance between four IPs Thomas Jefferson National Accelerator Facility Page 10

ELIC (e/p) Design Parameters

Beam energy Figure-8 ring Collision freq Beam current Particles/bunch Energy spread Bunch length, rms Hori. emit., norm.

Vertical emit., norm.

β* Vert. b-b tune-shift Peak lum. per IP Number of IPs Luminosity lifetime GeV km MHz A 10 9 10 -4 mm μm μm 250/ 10 0.22/ 0.55

2.7/ 6.9

0.70/ 51 0.03/ 2.0

150/ 7 2.5

499 0.15/ 0.33

1.9/ 4.1

3/ 3 5/ 5 0.42/ 35.6

0.017/ 1.4

50/ 5 0.18/ 0.38

2.3/ 4.8

.28/ 25.5

.028/ 2.6

mm 10 34 cm -2 s -1 2.9

5/5 0.01/ 0.1

1.2

4 24 1.1

hours

Electron parameters are red

Thomas Jefferson National Accelerator Facility Page 11

ELIC (e/A) Design Parameters

Ion Proton Deuteron 3 H +1 3 He +2 4 He +2 12 C +6 40 Ca +20 208 Pb +82 Max Energy (E i,max ) (GeV/nucleon) 150 75 50 100 75 75 75 59 Luminosity / n (7 GeV x E i,max ) 10 34 cm -2 s -1 2.6

2.6

2.6

1.3

1.3

0.4

0.13

0.04

Luminosity / n (3 GeV x E i,max /5) 10 33 cm -2 s -1 2.2

2.2

2.2

1.1

1.1

0.4

0.13

0.04

* Luminosity is given per nucleon per IP Thomas Jefferson National Accelerator Facility Page 12

Electron Polarization in ELIC

• Produced at electron source  Polarized electron source of CEBAF   Preserved in acceleration at recirculated CEBAF Linac Injected into Figure-8 ring with vertical polarization • Maintained in the ring  High polarization in the ring by electron self-polarization  SC solenoids at IPs removes spin resonances and energy sensitivity.

spin rotator spin rotator spin rotator with 90º solenoid snake collision point collision point collision point collision point spin rotator spin rotator with 90º solenoid snake spin rotator Thomas Jefferson National Accelerator Facility Page 13

Electron Polarization in ELIC (cont.) Electron/positron polarization parameters

Parameter Energy Beam cross bend at IP Radiation damping time Unit GeV mrad ms 3 70 50 Accumulation time Self-polarization time * Equilibrium polarization, max ** Beam run time s h % h 15 20 92 *

Time can be shortened using high field wigglers.

5 12 3.6 10 91.5 Lifetime 7 4 1 2 90

** Ideal max equilibrium polarization is 92.4%. Degradation is due to radiation in spin rotators.

Thomas Jefferson National Accelerator Facility Page 14

Positrons in ELIC

• Non-polarized positron bunches generated from modified electron injector through a converter • Polarization realized through self-polarization at ring arcs During positron production: - Polarized source is off - Dipoles are turned on

Thomas Jefferson National Accelerator Facility Page 15

Figure-8 Ion Ring (half)

-

Lattice at 225 GeV

Fri Nov 30 08:10:43 2007 OptiM - MAIN: - D:\ELIC\Ion Ring\FODO\low_emitt_225\spr_rec.opt

phase adv./cell ( Df x = 60 0 , Df y =60 0 )

0 BETA_X BETA_Y DISP_X DISP_Y

11 empty cells 3 transition cells 42 full cells Minimum dispersion (periodic) lattice 3 transition cells 11 empty cells

Arc dipoles:

: Dispersion suppression via ‘missing’ dipoles (geometrical) Uniform periodicity of Twiss functions (chromatic cancellations) $Lb=170 cm $B=73.4 kG $rho =102 m Arc quadrupoles: Dispersion pattern optimized for chromaticity compensation with sextupole families ( 3 × 60 0 = 180 0 ) $Lb=100 cm $G= 10.4 kG/cm

270 Thomas Jefferson National Accelerator Facility Page 16

Figure-8 Electron Ring (half)

-

Lattice at 9 GeV

Fri Nov 30 07:58:46 2007 OptiM - MAIN: - D:\ELIC\InteractionRegion\Electron\FODO_120_90_arc.opt

phase adv./cell ( Df x = 120 0 , Df y =120 0 )

BETA_X BETA_Y DISP_X 0 DISP_Y

83 empty cells 54 superperiods (3 cells/superperiod) ‘Minimized emittance dilution due to quantum excitations Limited synchrotron radiated power ( 14.3MW (total) @ 1.85A

) Quasi isochronous arc to alleviate bunch lengthening ( a ~10 -5 ) Dispersion pattern optimized for chromaticity compensation with sextupole families

88

83 empty cells

Arc dipoles:

: $Lb=100 cm $B=3.2 kG $rho =76 m Arc quadrupoles: $Lb=60 cm $G= 4.1 kG/cm

Thomas Jefferson National Accelerator Facility Page 17

Figure-8 Rings – Vertical ‘Stacking’

Thomas Jefferson National Accelerator Facility Page 18

IP Magnet Layout and Beam Envelopes

0.5m 3.2kG/cm 0.2m

22.2 mrad 1.27 deg 3.8m

IP 4.5m

8.4cm

10cm Vertical intercept 1.8m 20.8kG/cm 0.6m 2.55kG/cm 14.4cm 16.2cm

Vertical intercept

Thu Nov 29 23:16:54 2007 OptiM - MAIN: - D:\ELIC\InteractionRegion\IR\IR_elect_y.opt

   

N

 4mm

0 Ax_bet Ay_bet Ax_disp Ay_disp Thu Nov 29 23:19:38 2007 OptiM - MAIN: - D:\ELIC\InteractionRegion\IR\IR_ions_y.opt

5mm 3m 12KG/cm electron ion

10.3

22.9cm

Vertical intercept

0 Ax_bet Ay_bet Ax_disp Ay_disp

β* OK

Thomas Jefferson National Accelerator Facility Page 19 10.3

IR Final Quad

Optimization

• • 

IP configuration optimization “Lambertson”-type final focusing quad angle reduction: 100

mrad



22

mrad

10 cm 4.6cm

2.4cm

3cm Electron (9GeV) 8.6cm

Proton (225GeV) 1.8m

20.8kG/cm

1 st SC focusing quad for ion

14cm 10cm 2.4cm

3cm 4.8cm

Paul Brindza

Thomas Jefferson National Accelerator Facility Page 20

Lambertson Magnet Design

Cross section of quad with beam passing through magnetic Field in cold yoke around electron pass

.

Thomas Jefferson National Accelerator Facility Page 21

β Chromaticity correction with sextupoles

β- functions around the interaction region, the green arrows represent the sextupoles pairs.

Thu May 15 15:29:20 2008 OptiM - MAIN: - D:\Hisham Work\Accelerator Physics\Alex\IR\ELIC\IR_Arc\IR_elect_mirror

The phase advance, showing the –I transformation between the sextupoles pairs

0 BETA_X BETA_Y DISP_X DISP_Y Thu May 15 15:30:10 2008 OptiM - MAIN: - D:\Hisham Work\Accelerator Physics\Alex\IR\ELIC\IR_Arc\IR_elect_mirror 0 Q_X Q_Y Thomas Jefferson National Accelerator Facility Page 22 180 180

Local Correction of Transfer Map

Phase space in both transverse planes before and after applying the sextupoles Vertical plane Δp/p~0.0006

Initial phase space phase space after one pass through 2 IR’s No correction phase space after one pass through 2 IR’s after correction Y`

-0.003

Y

Y [cm] -0.003

Y [cm] View at the lattice end 0.003

-0.003

Y [cm] View at the lattice end 0.003

Thomas Jefferson National Accelerator Facility Page 23

Beam-Beam Effect in ELIC

Electron bunch IP Proton bunch Transverse beam-beam force

–

Highly nonlinear forces

–

Produce transverse kicks between colliding bunches Electron bunch proton bunch Beam-beam effect

– – –

Can cause size/emittance growth or blowup Can induce coherent beam-beam instabilities Can decrease luminosity and its lifetime One slice from each of opposite beams Beam-beam force y Impact of ELIC IP design

–

Highly asymmetric colliding beams (9 GeV/2.5 A on 225 GeV/1 A) x

– – – – – –

Four IPs and Figure-8 rings Strong final focusing (beta* 5 mm) Short bunch length (5 mm) Employs crab cavity vertical b-b tune shifts are 0.087/0.01

Very large electron synchrotron tune (0.25) due to strong RF focusing

–

Equal betatron phase advance (fractional part) between IPs Thomas Jefferson National Accelerator Facility Page 24

Beam-Beam Simulations

(cont.)

•

Simulation Model

–

Single/multiple IPs, head-on collisions

–

Strong-strong self consistent Particle-in-Cell codes, developed by J. Qiang of LBNL

–

Ideal rings for electrons & protons, including radiation damping & quantum excitations for electrons

•

Scope and Limitations

–

10k ~ 30k turns for a typical simulation run

–

0.05 ~ 0.15 s of storing time (12 damping times)



reveals short-time dynamics with accuracy



can’t predict long term (>min) dynamics

•

Simulation results

–

Saturated at 70% of peak luminosity, 5.8·10 34 the loss is mostly due to the hour-glass effect cm -2 s -1 ,

–

Luminosity increase as electron current linearly (up to 6.5 A), coherent instability observed at 7.5 A

– –

Luminosity increase as proton current first linearly then slow down due to nonlinear b-b effect, electron beam vertical size/emittance blowup rapidly Simulations with 4 IPs and 12-bunch/beam showed stable luminosity and bunch sizes after one damping time, situated luminosity is operation 5.5·10 34 cm -2 s -1 per IP, very small loss from single IP and Single bunch Supported by SciDAC 2.5

2 1.5

1 0.5

2 1.8

1.6

1.4

1.2

1 0.8

0.6

0.4

1 0.8

0.775

0.75

0.725

0.7

0.675

0.65

0.625

0.6

0 Thomas Jefferson National Accelerator Facility Old Working Point New Working Point 3 1.5

4 5 6 electron current (A) old Working Point New Working Point 2 2.5

proton current (A) 3

4IPs, 12 bunches/beam

1000 2000 3000 turns 4000 Page 25 7 3.5

5000 4 8 6000

ELIC Additional Key Issues

•

To achieve luminosity at

10 33

cm

-2

sec

-1

and

up



High energy electron cooling

•

To achieve luminosity at ~

10 35

cm

-2

sec

-1



Circulator Cooling



Crab cavity



Stability of intense ion beams Thomas Jefferson National Accelerator Facility Page 26

ELIC R&D: Forming Intense Ion Beam

Use stochastic cooling for stacking and pre-cooling  Stacking/accumulation process      Multi-turn (10 – 20) injection from SRF linac to pre-booster Damping of injected beam Accumulation of 1 A coasted beam at space charge limited emittence RF bunching/acceleration Accelerating beam to 3 GeV, then inject into large booster   Ion space charge effect dominates at low energy region Transverse pre-cooling of coasted beam in collider ring (30 GeV)

Stacking proton beam in pre booster with stochastic cooling

Parameter Beam Energy Momentum Spread Pulse current from linac Cooling time Accumulated current Stacking cycle duration Beam emittance, norm.

Laslett tune shift Unit MeV % mA s A Min μm Value 200 1 2 4 0.7

2 12 0.03

Transverse stochastic cooling of coasted proton beam after injection in collider ring

Parameter Beam Energy Momentum Spread Current Freq. bandwidth of amplifiers Minimal cooling time Initial transverse emittance IBS equilibrium transverse emitt.

Laslett tune shift at equilibrium Unit GeV % A GHz Min μm μm Value 30 0.5

1 5 8 16 0.1

0.04

Thomas Jefferson National Accelerator Facility Page 27

Injector and ERL for Electron Cooling

• ELIC CCR driving injector  30 mA@15 MHz, up to 125 MeV energy, 1 nC bunch charge, magnetized • Challenges  Source life time: 2.6 kC/day (state-of-art is 0.2 kC/day)  source R&D, & exploiting possibility of increasing evolutions in CCR  High beam power: 3.75 MW • Conceptual design  Energy Recovery  High current/brightness source/injector is a key issue of ERL based light source applications, much R&D has been done  We adopt light source injector as initial baseline design of ELIC CCR driving injector • Beam qualities should satisfy electron cooling requirements (based on previous computer simulations/optimization)

SRF modules solenoids 500keV DC gun buncher Thomas Jefferson National Accelerator Facility quads Page 28

Electron Cooling with a Circulator Ring

.

Effective for heavy ions (higher cooling rate), difficult for protons .



State-of-Art

• • Fermilab electron cooling demonstration (4.34 MeV, 0.5 A DC) Feasibility of EC with bunched beams remains to be demonstrated 

ELIC Circulator Cooler

• 3 A CW electron beam, up to 125 MeV • SRF ERL provides 30 mA CW beam • Circulator cooler for reducing average current from source/ERL • Electron bunches circulate 100 times in a ring while cooling ion beam • Fast (300 ps) kicker operating at 15 MHz rep. rate to inject/eject bunches into/out circulator-cooler ring

Thomas Jefferson National Accelerator Facility Page 29

Fast Kicker for Circulator Cooling Ring

• Sub-ns pulses of 20 kW and 15 MHz are needed to insert/extract individual bunches. • RF chirp techniques hold the best promise of generating ultra-short pulses. State-of-Art pulse systems are able to produce ~2 ns, 11 kW RF pulses at a 12 MHz repetition rate. This is very close to our requirement, and appears to be technically achievable.

Estimated parameters for the kicker

Beam energy MeV 125 Kick angle Integrated BdL Frequency BW Kicker Aperture 10 -4 GM GHz Cm 3 1.25 2 2 Peak kicker field G 3 • Helically-corrugated waveguide (HCW) exhibits dispersive qualities, and serves to further compress the output pulse without excessive loss. Powers ranging from up10 kW have been created with such a device. Kicker Repetition Rate Peak power/cell Average power/cell Number of cells MHz KW W 20 15 10 15 20 • Collaborative development plans include studies of HCW, optimization of chirp techniques, and generation of 1-2 kW peak output powers as proof of concept. • Kicker cavity design will be considered

kicker Thomas Jefferson National Accelerator Facility Page 30 kicker

Cooling Time and Ion Equilibrium

Cooling rates and equilibrium of proton beam Multi-stage cooling scenario:

•

1 st stage: longitudinal cooling at injection energy (after transverses stochastic cooling)

•

2 nd stage: initial cooling after acceleration to high energy

•

3 rd stage: continuous cooling in collider mode

Parameter Energy Particles/bunch Initial energy spread* Bunch length* Proton emittance, norm* Cooling time 

x

/

y

Equilibrium bunch length** Cooling time at equilibrium Laslett’s tune shift (equil.)

* max.amplitude

** norm.,rms

Unit GeV/Me V 10 10 10 -4 cm  m min  m Value 30/15 Value 225/123 0.2/1 30/3 20/3 1 1 1/1 1/2 1 1 1 1/0.04

cm min 2 0.1

0.04

0.5

0.3

0.02

Thomas Jefferson National Accelerator Facility Page 31

ELIC R&D: Crab Crossing



High repetition rate requires crab crossing to avoid parasitic beam beam interaction



Crab cavities needed to restore head-on collision & avoid luminosity reduction



Minimizing crossing angle reduces crab cavity challenges & required R&D State-of-art:

KEKB Squashed cell@TM110 Mode Crossing angle = 2 x 11 mrad V kick =1.4 MV, E sp = 21 MV/m

Thomas Jefferson National Accelerator Facility Page 32

ELIC R&D: Crab Crossing

(cont.) Crab cavity development Electron: 1.2 MV – within state of art (KEK, single Cell, 1.8 MV) Ion: 24 MV (Integrated B field on axis 180G/4m) Crab Crossing R&D program

–

Understand gradient limit and packing factor

–

Multi-cell SRF crab cavity design capable for high current operation.

–

Phase and amplitude stability requirements

–

Beam dynamics study with crab crossing Thomas Jefferson National Accelerator Facility Page 33

ELIC at JLab Site

City of NN VA State WM Symantec JLab/DOE SURA City of NN Thomas Jefferson National Accelerator Facility Page 34

Zero th –Order Design Report for the Electron-Ion Collider at CEBAF

A. Afanasev, A. Bogacz, P. Brindza, A. Bruell, L. Cardman, Y. Chao, S. Chattopadhyay, E. Chudakov, P. Degtiarenko, J. Delayen, Ya. Derbenev, R. Ent, P. Evtushenko, A. Freyberger, D. Gaskell, J. Grames, A. Hutton, R. Kazimi, G. Krafft, R. Li, L. Merminga, J. Musson, M. Poelker, A. Thomas, C. Weiss, B. Wojtsekhowski, B. Yunn, Y. Zhang

Thomas Jefferson National Accelerator Facility

Newport News, Virginia, USA W. Fischer, C. Montag

Brookhaven National Laboratory

Upton, New York, USA V. Danilov

Oak Ridge National Laboratory

Oak Ridge, Tennessee, USA V. Dudnikov

Brookhaven Technology Group

New York, New York, USA P. Ostroumov

Argonne National Laboratory

Argonne, Illinois, USA V. Derenchuk

Indiana University Cyclotron Facility

Bloomington, Indiana, USA A. Belov

Institute of Nuclear Research Thomas Jefferson National Accelerator Facility Page 35

“EICC” Proposal to Machine Groups

( after EIC workshop at Hampton University: not an official EICC recommendation, but rather an informal proposal from Abhay Deshpande, Richard Milner, Rolf Ent )

•

eRHIC:

1) Back to drawing board given unrealistic demands of the source.

2) Request staging of 5+ GeV with 10 32+ luminosity + cost estimates, with appropriate upgrade paths for luminosity and energy (including changing the RF/optics of the RHIC machine).

•

ELIC:

1) 1.5 GHz seems unrealistic, 0.5 GHz may be doable.

2) Request polarization tracking with full lattice.

3) Request consideration of staging options, if any.

In addition, request both for estimate of achievable vacuum levels asap.

Thomas Jefferson National Accelerator Facility Page 36

MEIC “Design” Group

A. Bogacz, Ya. Derbenev, R. Ent, G. Krafft T. Horn, C. Hyde, A. Hutton, F. Klein, P. Nadel-Turonski, A. Thomas, C. Weiss, Y. Zhang Thomas Jefferson National Accelerator Facility Page 37

Motivations

Science

•

Expand science program beyond 12 GeV CEBAF fixed target program

• • •

Gluons via J/ ψ production Higher CM energy in valence region Study the asymmetric sea for x≈m



/M N Accelerator

• •

Bring ion beams and associated technologies to JLab (a lepton lab) Have an early ring-ring collider at JLab

• •

Provides a test bed for new technologies required by ELIC Develop expertise and experience, acquire/train technical staff Staging Possibilities

•

A medium energy EIC becomes the low energy ELIC ion complex

•

Exploring opportunities for reusing J ϋlich’s Cooler Synchrotron (COSY) complex for cost saving Thomas Jefferson National Accelerator Facility Page 38

Parameter

s Luminosity Beam apertures Lifetime

Design Goals

Value or range

100 - 500 Momenta ( GeV/c ) 5 on 5 to 11 on 11 10 33 cm -2 sec -1  *, emittance,etc.

Detector space RF frequency 8 meters 0.5 GHz max.

10 sigma (proton), 13 sigma (electron) 24 hours

Notes

Sufficient headroom to access sea quark region, allow higher Q 2 for DES.

Symmetric momenta, and use CEBAF to our advantage.

Deep exclusive reactions need good M x 2 resolution.

Use conservative parameters Like CLAS or PANDA If crab crossing angle, if not likely need lower value.

Radius Can vary slightly

Thomas Jefferson National Accelerator Facility Page 39

Stage 1: Low Energy Collider

IP SRF Linac Ion Sources p e Booster/collider ring • Two compact rings of 300 m length • Collision momenta up to 5 GeV/c for electrons & (Z/A) ×5 GeV/cu for ions • Electron & stochastic cooling • One IP Electron injector 12 GeV CEBAF •

A compact booster/storage ring of 300 m length will be used for accumulating, boosting and cooling up to 2.5 GeV/cu (Z/A=1/2) ion beams or 5 GeV/c protons from an ion source and SRF injection linac.

•

Full injection energy electron storage ring and the ion ring act as collider rings for electron-ion collisions

•

More compact size enables storing higher ion beam current for the same Laslett space charge tune-shift Thomas Jefferson National Accelerator Facility Page 40

MEIC & Staging of ELIC: Alternative Pass

The tunnel houses 3 rings: Electron ring up to 5 GeV/c Ion ring up to 5 GeV/c Superconducting ion ring for up to 30 GeV/c p Ion Sources SRF Linac e p (Ya. Derbenev, etc.) Electron injector Low energy collider (stage 1)  (up to 5GeV/c for both e and i) Both e and p in compact ring (~ 300 m) Medium energy collider (stage 2)  (up to 5GeV/c for e, 30 GeV/c for i) Compact superconducting ion ring (~ 300 m) Medium energy collider (Stage 3)  (up to 11 GeV/c for e, 30 GeV/c for i) Large Figure-8 electron ring (1500 m to 2500 m) High energy collider (stage 4)  (up to 11 GeV/c for e, 250 GeV/c for i) Large Figure-8 super conducting ion ring (Full ELIC) e 12 GeV CEBAF p Figure-8 collider ring e

Thomas Jefferson National Accelerator Facility Page 41

Medium Energy EIC Features

•

High luminosity collider

•

CM energy region from 10 GeV (5x5 GeV) to 22 GeV (11x11 GeV), and possibly reaching 35 GeV (30x10 GeV)

•

High polarization for both electron and light ion beams

•

Natural staging path to high energy ELIC

•

Possibility of positron-ion collider in the low to medium energy region

•

Possibility of electron-electron collider (7x7 GeV) using just small 300 m booster/collider ring Thomas Jefferson National Accelerator Facility Page 42

Luminosity

Design luminosity L~ 2 ×10 33 cm -2 s -1 (9 GeV protons x 9 GeV electrons) Limiting Factors

•

Space charge effect for low ion energy

• •

Electron beam current due to synchrotron radiation Beam-beam effect Luminosity Concepts

• • • •

High bunch collision frequency (up to 0.5 GHz) Long ion bunches with respect to β* for high bunch charge (σ Super strong final focusing ( β* ~ 2.5 mm to 5 mm) Large beam-beam parameters (0.015/0.1 per IP for p and e) z ~ 5 cm)

• • •

Need staged cooling for ion beams Need crab crossing colliding beams Need “traveling focusing” to suppress the hour-glass effect Thomas Jefferson National Accelerator Facility Page 43

Parameter Table

Beam Energy Circumference Beam Current Repetition Rate Particles per Bunch Bunch Length Normalized Hori. Emittance Normalized Vert. Emittance Horizontal

β

* Vertical

β

* Beam Size at IP (x/y) Horizontal B-B Tune Shift Vertical B-B Tune Shift Laslett Tune Shift Luminosity GeV m A GHz 10 10 cm mm mrad mm mrad cm cm

µ

m 10 33 s -1 cm -2 5/ 5 320 0.2/ 0.65

0.5

0.25/ 0.8

5/ 0.25

0.27/ 48 0.27/ 4.8

0.5/ 5 0.25/ 25 14.3/ 14.3

0.004/ .014

0.003/ 0.1

0.1/ small 0.6

9/ 9 1370 0.17/ 2.85

0.5

0.21/ 3.6

5/ 0.25

0.34/ 62 0.34/ 3.9

0.5/ 5 0.25/ 40 13.3/ 9.4

.015/ .01

.011/ 0.1

.09/ small 2.4

11/ 11 1370 0.14/ 1.25

0.5

0.17/ 1.56

5/ 0.25

0.17/ 62 0.17/ 2.5

1/ 5 0.25/ 31 12/ 6 0.015/ 0.01

0.008/ 0.1

.096/ small 1.5

30/ 10 1370 0.24/ 1.82

0.5

0.3/ 2.3

1/ 0.25

0.22/ 135 0.22/ 5.4

0.5/ 0.5

0.25/ 6.25

5.9/ 4.2

.015/ .006

.01/ 0.1

.089/ small 10.8

Electron parameters are red

Thomas Jefferson National Accelerator Facility Page 44

Production of Ion Beam

•

One Idea

–

SRF to 50 to 300 MeV/c

–

Accumulate current in Low Energy Ring

–

Accelerate to final energy

–

Store in Low Energy Ring or send on to next ring

•

Another Idea

–

Accelerate to ~ 2 GeV/c in an SRF linac

–

Accumulate current in Low Energy Ring

–

Accelerate to final energy

–

Store in Low Energy Ring or send on to next ring Thomas Jefferson National Accelerator Facility Page 45

Interaction Region: Simple Optics

Beta functions Mon Dec 01 12:26:08 2008 OptiM - MAIN: - N:\bogacz\Pelican\IR_ion_LR.opt

Beam envelopes (

σ

RMS ) for

ε

N = 0.2 mm mrad Mon Dec 01 12:30:09 2008 OptiM - MAIN: - N:\bogacz\Pelican\IR_ion_LR.opt

 max 0 BETA_X BETA_Y   ┴ * = 5mm DISP_X 8 m      

s

2   max   * 

f

2

tripl

 * ,

f

2

tripl

 DISP_Y * 0 Ax_bet Ay_bet  * = 14  m Ax_disp Ay_disp 31.22

8 m Triplet based IR Optics • first FF quad 4 m from the IP • typical quad gradients ~ 12 Tesla/m for 5 GeV/c protons • beam size at FF quads,

σ

RMS ~ 1.6 cm 31.22

Thomas Jefferson National Accelerator Facility Page 46

Interaction Region: Crab Crossing

 High bunch repetition rate requires crab crossing colliding beam to avoid parasitic beam-beam interactions  Crab cavities needed to restore head-on collision & avoid luminosity reduction  Since ion beam energy now is a factor of 15 lower than that of ELIC, integrated kicking voltage is at order of 1 to 2 MV, within the state-of-art (KEK)  No challenging cavity R&D required

State-of-art:

KEKB Squashed cell@TM110 Mode Crossing angle = 2 x 11 mrad V kick =1.4 MV, E sp = 21 MV/m

Thomas Jefferson National Accelerator Facility Page 47

Interaction Region: Traveling Focusing

• Under same space charge tune-shift limit, we need to increase ion bunch length in order to increase bunch charge, and hence increase luminosity • Hour glass effect would normally kill collider luminosity if ion bunch length is much large than

β

* • “Traveling Focusing” scheme can mitigate hour-glass effect by moving the final focusing point along the long ion bunch. This setup enables the short electron bunch to collide with different slices of the long ion bunch at their relative focusing points • Nonlinear elements (sextupoles) working with linear final focusing block produce non-uniform focus length for different slices of a long bunch slice 1 Brinkmann and Dohlus, Ya. Derbenev, Proc. EPAC 2002 F1 slice 1 slice 2 sextupole F2 slice 2

Thomas Jefferson National Accelerator Facility Page 48

COSY as Pre-Booster/Collider Ring

• COSY complex provides a good solution for the EIC pre-booster/low energy collider ring • Adding 4 dipoles on each arc can bring maximum momentum of COSY synchrotron from 3.7 GeV/c to 5 GeV/c, while still preserving its optics • COSY existing cooling facilities can be reused

New superperiod Preserve ring optics Thomas Jefferson National Accelerator Facility Page 49

mEIC@JLAB

Unique opportunity for nucleon structure physics

• • • Can complete a substantial part of the EIC spin / GPD / TMD program, which is difficult to do with only a high-energy collider High luminosity at medium energy (> 10 33 ) Symmetric kinematics improve resolution, acceptance, and particle identification ep →epπ +

Cost-effective staging path for ELIC

• • • Required booster rings will serve as colliders Flexible staging options with clear physics goals Fast track possible (small / large rings) ELIC mEIC low-E IP large e ring small e ring

Thomas Jefferson National Accelerator Facility Page 50

mEIC: exclusive highlights

• e-p: GPDs – Deep exclusive meson production: spin/flavor/spatial quark structure – DVCS: helicity GPDs, spatial quark and gluon imaging – – J/ ψ: spatial distribution of gluons D Λ c , open charm (including quasi-real D 0 photoproduction for Δ G) • e-A: coherent nuclear processes – Largely unexplored – – – DVCS: matter vs. charge radius J/ ψ : gluonic radius of nucleus meson production: QCD dynamics, color transparency -

Thomas Jefferson National Accelerator Facility Page 51

mEIC: (semi-)inclusive highlights

• e-p: polarized SIDIS – – TMDs: spin-orbit interactions from azimuthal asymmetries, p T dependence Flavor decomposition: q ↔ q, u ↔ d, strangeness – Target fragmentation and fracture functions • e-p: polarized DIS – Δ G and Δ q+ Δ q from global fits (+JLab 12 GeV, COMPASS) • e-A: polarized DIS – Neutron structure: spectator tagging in d(e,e’p)X – EMC effect: shadowing at 10 -3 < x <10 -2

Thomas Jefferson National Accelerator Facility Page 52

Key R&D Issues

•

Forming low energy ion beam and space charge effect

•

Cooling of ion beams

•

Traveling focusing scheme

•

Beam-beam effect

•

Beam dynamics of crab crossing beams Thomas Jefferson National Accelerator Facility Page 53

EIC Research Plans

• •

Recently submitted to DOE, in conjunction with BNL, for inclusion as “stimulus” funding (15.4 M$ over 5 year grant period) Items

–

Common Items

• • • •

Electron Cooling (BNL) 8.0 M$ ERL Technology (JLAB) 8.5 M$ Polarized 3 He Source (BNL) 2.0 M$ Crab Cavities (JLAB) 2.8 M$

–

ELIC Specific Items

• • •

Space Charge Effects Evaluation 0.9 M$ Spin Tracking inc. beam-beam 1.6 M$ Simulations and Traveling Focus Scheme 1.6 M$ Thomas Jefferson National Accelerator Facility Page 54

Summary

The ELIC Design Team has continued to make progress on the ELIC design

 More complete beam optics    Chromaticity correction Crab crossing and crab cavity reduction Beam-beam effects

The ELIC design has evolved

  CW electron cooling with circulator ring Ions up to lead now in design

We continue design advances/optimization

   Resolve (design) high rep.rate issue (high lumi vs detector) Minimize quantum depolarization of electrons (spin matching) Study ion stability

Thomas Jefferson National Accelerator Facility Page 55

Summary

• •

We have investigated various staging ideas for ELIC These ideas start with building a high luminosity, low energy (p < 5 GeV/c) symmetric collider

• •

This complex could be followed by a high luminosity medium energy symmetric collider (5 GeV/c < p < 11 GeV/c)

•

This equipment would provide beams for injection into the final ELIC complex The initial design studies indicate that luminosity of this collider can reach up to 2 ×10 33 cm -2 s -1 . This luminosity relays on staged ion beam cooling, crab crossing beam and traveling focusing interaction region design.

Thomas Jefferson National Accelerator Facility Page 56

Summary

• • •

All three colliders could run simultaneously, if physics interest stays strong in the early ones To reduce cost, it may be possible to reuse a substantial portion of the present COSY facility; especially in Stage I. Collaboration between Jefferson Lab and J ϋlich has been initiated.

Additional major R&D will be needed on the ion beam space charge effect and travel focusing scheme. Crab cavities and electron cooling should not be challenging. Thomas Jefferson National Accelerator Facility Page 57