design status of elic g. a. krafft for elic design team and medium energy collider design team
DESCRIPTION
Design Status of ELIC G. A. Krafft for ELIC Design Team and Medium Energy Collider Design Team Jefferson Lab Physics Seminar Feb 6, 2009. Outline. ELIC: An Electron-Ion Collider at CEBAF Basic parameters List of recent developments/specs Some R&D Issues Electron Cooling - PowerPoint PPT PresentationTRANSCRIPT
Thomas Jefferson National Accelerator Facility Page 1
Design Status of ELIC
G. A. Krafft for ELIC Design Team
and Medium Energy Collider Design Team
Jefferson Lab Physics SeminarFeb 6, 2009
Thomas Jefferson National Accelerator Facility Page 2
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
Thomas Jefferson National Accelerator Facility Page 3
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
Thomas Jefferson National Accelerator Facility Page 4
Jefferson Lab Now
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RHIC Lab Now
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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
Thomas Jefferson National Accelerator Facility Page 7
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
Thomas Jefferson National Accelerator Facility Page 8
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
Thomas Jefferson National Accelerator Facility Page 9
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 10
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
Thomas Jefferson National Accelerator Facility Page 11
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
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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
Thomas Jefferson National Accelerator Facility Page 13
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
Thomas Jefferson National Accelerator Facility Page 14
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
Thomas Jefferson National Accelerator Facility Page 15
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
Thomas Jefferson National Accelerator Facility Page 16
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)
Thomas Jefferson National Accelerator Facility Page 17
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]
BETA_X BETA_Y DISP_X DISP_Y
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
Thomas Jefferson National Accelerator Facility Page 18
Figure-8 Rings – Vertical ‘Stacking’
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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
]
Ax_bet Ay_bet Ax_disp Ay_disp
4mmelectron
N
β* OK
Thomas Jefferson National Accelerator Facility Page 20
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
Thomas Jefferson National Accelerator Facility Page 21
Lambertson Magnet Design
magnetic Field in cold yoke around electron pass.
Cross section of quad with beam passing through
Thomas Jefferson National Accelerator Facility Page 22
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]
BETA_X BETA_Y DISP_X DISP_Y
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
Thomas Jefferson National Accelerator Facility Page 23
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
Thomas Jefferson National Accelerator Facility Page 24
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
Thomas Jefferson National Accelerator Facility Page 25
• 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
Thomas Jefferson National Accelerator Facility Page 26
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
Thomas Jefferson National Accelerator Facility Page 27
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
Thomas Jefferson National Accelerator Facility Page 28
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
Thomas Jefferson National Accelerator Facility Page 29
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 30
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
Thomas Jefferson National Accelerator Facility Page 31
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
Thomas Jefferson National Accelerator Facility Page 32
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
Thomas Jefferson National Accelerator Facility Page 33
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.)
Thomas Jefferson National Accelerator Facility Page 34
ELIC at JLab Site
920 m360 m
WMSymantec
SURA
City of NN
VA State
City of NN
JLab/DOE
Thomas Jefferson National Accelerator Facility Page 35
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
Thomas Jefferson National Accelerator Facility Page 36
“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)
Thomas Jefferson National Accelerator Facility Page 37
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 38
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
Thomas Jefferson National Accelerator Facility Page 39
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
Thomas Jefferson National Accelerator Facility Page 40
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
Thomas Jefferson National Accelerator Facility Page 41
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
Thomas Jefferson National Accelerator Facility Page 42
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 43
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
Thomas Jefferson National Accelerator Facility Page 44
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
Thomas Jefferson National Accelerator Facility Page 45
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 46
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]
Ax_bet Ay_bet Ax_disp Ay_disp
* = 14m
Thomas Jefferson National Accelerator Facility Page 47
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
Thomas Jefferson National Accelerator Facility Page 48
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
Thomas Jefferson National Accelerator Facility Page 49
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 50
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+
Thomas Jefferson National Accelerator Facility Page 51
-
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
Thomas Jefferson National Accelerator Facility Page 52
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)
-
-
Thomas Jefferson National Accelerator Facility Page 53
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 54
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$
Thomas Jefferson National Accelerator Facility Page 55
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 56
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.
Thomas Jefferson National Accelerator Facility Page 57
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.