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

Thomas Jefferson National Accelerator Facility

Design Status of ELIC

G. A. Krafft for ELIC Design Team

and Medium Energy Collider Design Team

Jefferson Lab Physics SeminarFeb 6, 2009


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 StagingSummary


ELIC Study Group & CollaboratorsA. 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


Jefferson Lab Now


RHIC Lab Now


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 • 1033 up to 1035 cm-2 s-1 per interaction point

Ion Species• Polarized H, D, 3He, 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

ELIC Design Goals


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…)

Evolution of the Principal Scheme


ELIC Conceptual Design

3-9 GeV electrons

3-9 GeV positrons

30-225 GeV protons

15-100 GeV/n ions

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

prebooster

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.


Achieving High Luminosity of ELICELIC design luminosity

L~ 2.6 x 1034 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 (σz ~ 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


ELIC (e/p) Design ParametersBeam energy GeV 250/10 150/7 50/5

Figure-8 ring km 2.5

Collision freq MHz 499

Beam current A 0.22/0.55 0.15/0.33 0.18/0.38

Particles/bunch 109 2.7/6.9 1.9/4.1 2.3/4.8

Energy spread 10-4 3/3

Bunch length, rms mm 5/5

Hori. emit., norm. μm 0.70/51 0.42/35.6 .28/25.5

Vertical emit., norm. μm 0.03/2.0 0.017/1.4 .028/2.6

β* mm 5/5

Vert. b-b tune-shift 0.01/0.1

Peak lum. per IP 1034 cm-2s-1 2.9 1.2 1.1

Number of IPs 4

Luminosity lifetime hours 24

Electron parameters are red


ELIC (e/A) Design Parameters

Ion Max Energy(Ei,max)

Luminosity / n (7 GeV x Ei,max)

Luminosity / n(3 GeV x Ei,max/5)

(GeV/nucleon) 1034 cm-2 s-1 1033 cm-2 s-1

Proton 150 2.6 2.2Deuteron 75 2.6 2.2

3H+1 50 2.6 2.23He+2 100 1.3 1.14He+2 75 1.3 1.112C+6 75 0.4 0.4

40Ca+20 75 0.13 0.13208Pb+82 59 0.04 0.04

* Luminosity is given per nucleon per IP


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 rotatorspin rotator

spin rotatorspin rotator

collision point

spin rotator with 90º solenoid snake

collision point

collision point

collision point

spin rotator with 90º solenoid snake


Electron Polarization in ELIC (cont.)

* Time can be shortened using high field wigglers.

** Ideal max equilibrium polarization is 92.4%. Degradation is due

to radiation in spin rotators.

Parameter Unit Energy GeV 3 5 7 Beam cross bend at IP mrad 70 Radiation damping time ms 50 12 4 Accumulation time s 15 3.6 1 Self-polarization time* h 20 10 2 Equilibrium polarization, max** % 92 91.5 90 Beam run time h Lifetime

Electron/positron polarization parameters


Positrons in ELIC• Non-polarized positron bunches generated from

modified electron injector through a converter• Polarization realized through self-polarization at ring

arcs

115 MeV

converter

e-

e-15 MeV

5 MeVe+

e-

e-

e-

e+

10 MeV

15 MeV

e-

e+e+

unpolarizedsource

polarized source

dipole

Transverse emittance

filter

Longitudinal emittance filter

dipole dipole115 MeV

converter

e-

e-15 MeV

5 MeVe+

e-

e-

e-

e+

10 MeV

15 MeV

e-

e+e+

unpolarizedsource

polarized source

During positron production: - Polarized source is off - Dipoles are turned on

dipole

Transverse emittance

filter

Longitudinal emittance filter

dipole dipole


2700

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

300

50

BETA

_X&Y[m

]

DIS

P_X

&Y[m

]

BETA_X BETA_Y DISP_X DISP_Y

Figure-8 Ion Ring (half) - Lattice at 225 GeV

42 full cells

11 empty cells

11 empty cells

3 transition cells

3 transition cells

phase adv./cell (Dfx= 600, Dfy=600)

Arc dipoles::

$Lb=170 cm$B=73.4 kG$rho =102 m

Arc quadrupoles:

$Lb=100 cm$G= 10.4 kG/cm

Minimum dispersion (periodic) latticeDispersion suppression via ‘missing’ dipoles (geometrical)Uniform periodicity of Twiss functions (chromatic cancellations)

Dispersion pattern optimized for chromaticity compensation with sextupole families (3 × 600 = 1800)


Figure-8 Electron Ring (half) - Lattice at 9 GeV

54 superperiods (3 cells/superperiod)

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

83 empty cells

880

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

200

0.3

-0.3

BE

TA_X

&Y

[m]

DIS

P_X

&Y

[m]


phase adv./cell (Dfx= 1200, Dfy=1200)

‘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


Figure-8 Rings – Vertical ‘Stacking’


IP Magnet Layout and Beam Envelopes

IP 10cm 1.8m 20.8kG/c

m3m 12KG/cm

0.5m 3.2kG/cm

0.6m 2.55kG/c

m8.4cm

22.2 mrad

1.27 deg

0.2m

Vertical intercept4.5m

3.8m

14.4cm 16.2cm

Vertical intercept

22.9cmVertical

intercept

10.30

Thu Nov 29 23:19:38 2007 OptiM - MAIN: - D:\ELIC\InteractionRegion\IR\IR_ions_y.opt

0.5

0

10

Siz

e_X

[cm

]

Siz

e_Y

[cm

]

Ax_bet Ay_bet Ax_disp Ay_disp

ion5mm

10.30

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

0.5

0

0.5

0

Siz

e_X

[cm

]

Siz

e_Y

[cm

]


4mmelectron

N

β* OK


Optimization • IP configuration optimization• “Lambertson”-type final focusing quad angle reduction: 100 mrad 22 mrad

IR Final Quad

10 cm

14cm3cm

1.8m20.8kG/cm

4.6cm 8.6cm

Electron (9GeV)

Proton (225GeV)

2.4cm

10cm

2.4cm

3cm

4.8cm

1st SC focusing quad for ion

Paul Brindza


Lambertson Magnet Design

magnetic Field in cold yoke around electron pass.

Cross section of quad with beam passing through


β Chromaticity correction with sextupoles

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

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

1800

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

900

0

5-5

BE

TA_X

&Y

[m]

DIS

P_X

&Y

[m]


1800

Thu May 15 15:30:10 2008 OptiM - MAIN: - D:\Hisham Work\Accelerator Physics\Alex\IR\ELIC\IR_Arc\IR_elect_mirror

0.51

0P

HA

SE

_X&

Y

Q_X Q_Y


Local Correction of Transfer Map

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

phase space after one pass through 2 IR’s after correction

Vertical plane Δp/p~0.0006

0.003-0.003 Y [cm] View at the lattice beginning

1.2

-1.2

Y`[m

rad]

0.003-0.003 Y [cm] View at the lattice end

1.2

-1.2

Y`[m

rad]

0.003-0.003 Y [cm] View at the lattice end

1.2

-1.2

Y`[m

rad]

Y

Y`

Phase space in both transverse planes before and after applying the sextupoles


Beam-Beam Effect in ELICTransverse beam-beam force

– Highly nonlinear forces– Produce transverse kicks between colliding

bunches

Beam-beam effect– Can cause size/emittance growth or blowup– Can induce coherent beam-beam instabilities– Can decrease luminosity and its lifetime

Impact of ELIC IP design– Highly asymmetric colliding beams

(9 GeV/2.5 A on 225 GeV/1 A)– 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

Electron bunch

Proton bunch

IP

Electron bunchproton bunch

x

y

One slice from each of opposite beams

Beam-beam force


• 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, 5.8·1034 cm-2s-1,

the loss is mostly due to the hour-glass effect– 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 5.5·1034 cm-2s-1 per IP, very small loss from single IP and Single bunch operation

Supported by SciDAC

Beam-Beam Simulations(cont.)

0.5

1

1.5

2

2.5

2 3 4 5 6 7 8electron current (A)

lum

i (no

rm)

Old Working Point

New Working Point

0.40.60.8

11.21.41.61.8

1 1.5 2 2.5 3 3.5 4proton current (A)

lum

i (no

rm)

old Working Point

New Working Point

0.60.625

0.650.675

0.70.725

0.750.775

0.8

0 1000 2000 3000 4000 5000 6000turns

lum

i (no

rm)

4IPs, 12 bunches/beam


ELIC Additional Key Issues

• To achieve luminosity at 1033 cm-2 sec-1 and up High energy electron cooling

• To achieve luminosity at ~ 1035 cm-2 sec-1

Circulator Cooling Crab cavity Stability of intense ion beams


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)

Parameter Unit Value

Beam Energy MeV 200

Momentum Spread % 1

Pulse current from linac mA 2

Cooling time s 4

Accumulated current A 0.7

Stacking cycle duration Min 2

Beam emittance, norm. μm 12

Laslett tune shift 0.03

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

Parameter Unit Value

Beam Energy GeV 30

Momentum Spread % 0.5

Current A 1

Freq. bandwidth of amplifiers GHz 5

Minimal cooling time Min 8

Initial transverse emittance μm 16

IBS equilibrium transverse emitt. μm 0.1

Laslett tune shift at equilibrium 0.04

Stacking proton beam in pre-booster with stochastic cooling


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 Energy Recovery• Conceptual design

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)

500keV DC gun

solenoids

buncher

SRF modules

quads


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


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.

• 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.

Estimated parameters for the kickerBeam energy MeV 125

Kick angle 10-4 3Integrated BdL GM 1.25 Frequency BW GHz 2

Kicker Aperture Cm 2

Peak kicker field G 3

Kicker Repetition Rate

MHz 15

Peak power/cell KW 10

Average power/cell W 15

Number of cells 20 20

kicker

kicker

• 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


Cooling Time and Ion Equilibrium

* max.amplitude** norm.,rms

Cooling rates and equilibrium of proton beam

yx /

Parameter Unit Value Value

Energy GeV/MeV

30/15 225/123

Particles/bunch 1010 0.2/1

Initial energy spread* 10-4 30/3 1/2

Bunch length* cm 20/3 1

Proton emittance, norm* m 1 1

Cooling time min 1 1

Equilibrium emittance , ** m 1/1 1/0.04

Equilibrium bunch length** cm 2 0.5

Cooling time at equilibrium min 0.1 0.3

Laslett’s tune shift (equil.) 0.04 0.02

Multi-stage cooling scenario: • 1st stage: longitudinal cooling

at injection energy (after transverses stochastic cooling)

• 2nd stage: initial cooling after acceleration to high energy

• 3rd stage: continuous cooling in collider mode


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

Vkick=1.4 MV, Esp= 21 MV/m


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

ELIC R&D: Crab Crossing (cont.)


ELIC at JLab Site

920 m360 m

WMSymantec

SURA

City of NN

VA State

City of NN

JLab/DOE


Zeroth–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 http://casa.jlab.org/research/elic/elic_zdr.doc


“EICC” Proposal to Machine Groups

• eRHIC:1) Back to drawing board given unrealistic demands of the source.2) Request staging of 5+ GeV with 1032+ 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.

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


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


MotivationsScience

• 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/MN

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 Jϋlich’s Cooler Synchrotron (COSY)

complex for cost saving


Design GoalsParameter Value or range Notess 100 - 500 Sufficient headroom to access sea

quark region, allow higher Q2 for DES.

Momenta (GeV/c)

5 on 5 to 11 on 11 Symmetric momenta, and use CEBAF to our advantage.

Luminosity 1033 cm-2sec-1 Deep exclusive reactions need good Mx

2 resolution.*, emittance,etc.

Use conservative parameters

Detector space 8 meters Like CLAS or PANDARF frequency 0.5 GHz max. If crab crossing angle, if not likely

need lower value.Beam apertures 10 sigma (proton),

13 sigma (electron)

Radius

Lifetime 24 hours Can vary slightly


Stage 1: Low Energy Collider

• 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

Ion Sources

SRF Linac

Electron injector 12 GeV CEBAF

ep

Booster/collider ring

IP• 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


MEIC & Staging of ELIC: Alternative Pass

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)

High

Energ

y IP

(Ya. Derbenev, etc.)

Ion Sources

SRF Linac

p

Electron injector 12 GeV CEBAF

ee e

pFigure-8 collider

ring

pThe 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

Low

Energ

y IP


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


LuminosityDesign luminosity

L~ 2×1033 cm-2s-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 (σz ~ 5 cm)• 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)

• Need staged cooling for ion beams• Need crab crossing colliding beams• Need “traveling focusing” to suppress the hour-glass effect


Parameter TableBeam Energy GeV 5/5 9/9 11/11 30/10Circumference m 320 1370 1370 1370Beam Current A 0.2/0.65 0.17/2.85 0.14/1.25 0.24/1.82Repetition Rate GHz 0.5 0.5 0.5 0.5Particles per Bunch 1010 0.25/0.8 0.21/3.6 0.17/1.56 0.3/2.3Bunch Length cm 5/0.25 5/0.25 5/0.25 1/0.25Normalized Hori. Emittance mm mrad 0.27/48 0.34/62 0.17/62 0.22/135Normalized Vert. Emittance mm mrad 0.27/4.8 0.34/3.9 0.17/2.5 0.22/5.4Horizontal β* cm 0.5/5 0.5/5 1/5 0.5/0.5Vertical β* cm 0.25/25 0.25/40 0.25/31 0.25/6.25Beam Size at IP (x/y) µm 14.3/14.3 13.3/9.4 12/6 5.9/4.2Horizontal B-B Tune Shift 0.004/.014 .015/.01 0.015/0.01 .015/.006Vertical B-B Tune Shift 0.003/0.1 .011/0.1 0.008/0.1 .01/0.1Laslett Tune Shift 0.1/small .09/small .096/small .089/smallLuminosity 1033s-1cm-2 0.6 2.4 1.5 10.8

Electron parameters are red


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


Interaction Region: Simple Optics

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, σRMS ~ 1.6 cm

Beta functions Beam envelopes (σRMS) for εN = 0.2 mm mrad

2

2max * 2 max *

*

( )

,

tripltripl

ss

ff

* = 14m

┴* = 5mm

max ~ 9 km

8 m

f ~ 7 m 31.220

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

1200

00

50

BETA

_X&

Y[m

]

DIS

P_X&

Y[m

]BETA_X BETA_Y DISP_X DISP_Y

max ~ 9 km

┴* = 5mm

f ~ 7 m

8 m

31.220

Mon Dec 01 12:30:09 2008 OptiM - MAIN: - N:\bogacz\Pelican\IR_ion_LR.opt 2

0

20

Size

_X[c

m]

Size

_Y[c

m]


* = 14m


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

Vkick=1.4 MV, Esp= 21 MV/m


Interaction Region: Traveling Focusing

F1

slice 2

slice 1

F2sextupole

slice 1

slice 2

Brinkmann and Dohlus,

Ya. Derbenev, Proc. EPAC 2002

• 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


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


3/5

9 /10

,

3/30

10/25

010

/30

ELIC mEIC low-E IP

large e- ring small e- ring

mEIC@JLABUnique 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 (> 1033)

• Symmetric kinematics improve resolution, acceptance, and particle identificationCost-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)

ep →epπ+


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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 Λc, open charm (including quasi-real D0 photoproduction

for ΔG)• e-A: coherent nuclear processes

– Largely unexplored– DVCS: matter vs. charge radius– J/ψ: gluonic radius of nucleus– meson production: QCD

dynamics, color transparency


mEIC: (semi-)inclusive highlights

• e-p: polarized SIDIS– TMDs: spin-orbit interactions from azimuthal

asymmetries, pT dependence– Flavor decomposition: q ↔ q, u ↔ d, strangeness– Target fragmentation and fracture functions

• e-A: polarized DIS– Neutron structure: spectator tagging in d(e,e’p)X – EMC effect: shadowing at 10-3 < x <10-2

• e-p: polarized DIS– ΔG and Δq+Δq from global fits (+JLab 12 GeV, COMPASS)

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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


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 3He 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$


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


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 ×1033 cm-2s-1. This luminosity relays on staged ion beam cooling, crab crossing beam and traveling focusing interaction region design.


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 Jϋlich 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.

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

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