Transcript Status of Medium-energy Electron Ion Collider (MEIC) Design Vasiliy Morozov on behalf of MEIC Study Group JLab Users Group Meeting, June 3, 2015

Status of
Medium-energy Electron Ion Collider (MEIC)
Design
Vasiliy Morozov on behalf of MEIC Study Group
JLab Users Group Meeting, June 3, 2015
Outline
EIC Science highlights and design strategies for the MEIC at JLAB
MEIC baseline design
− Overview of collider complex components
− Detector integration
− Electron cooling
− Polarization
− Machine performance
− R&D overview
Summary and Outlook
IPAC’15,
Richmond,
May 5, 2015
2 3, 2015
JLab Users
Group Meeting,
June
22
MEIC Timeline and context
MEIC design (10+ years)
Physics case and machine requirements defined by White Paper (2011)
Preliminary conceptual design report (2012)
Design optimization, EICAC reviews, internal reviews
NSAC/LRP process starts (2014)
NASC/LRP Cost Review (January 2015)
Final design optimizations (February-June 2015)  baseline
Pre-project R&D planning and execution (2015-2017)
Conceptual Design Report planning and execution (2015-2017)
GOAL: Ready for CD1 and down-select
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Richmond,
May 5, 2015
3 3, 2015
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June
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Electron Ion Collider
NSAC 2007 Long-Range Plan:
“An Electron-Ion Collider (EIC) with
polarized beams has been embraced by
the U.S. nuclear science community as
embodying the vision for reaching the next
QCD frontier. EIC would provide unique
capabilities for the study of QCD well
beyond those available at existing facilities
worldwide and complementary to those
planned for the next generation of
accelerators in Europe and Asia.”
EIC Community White Paper arXiv:1212.1701
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Richmond,
May 5, 2015
4 3, 2015
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June
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EIC Physics Highlights
An EIC will study the sea quark
and gluon-dominated matter
– 3D structure of nucleons
 How do gluons and quarks bind into
3D hadrons?
– Role of orbital motion and gluon
dynamics in the proton spin
 Why do quarks contribute only ~30%?
– Gluons in nuclei (splitting/recombining)
 Does the gluon density saturate at small x?
Need luminosity, polarization and good
acceptance to detect spectator & fragments
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Richmond,
May 5, 2015
5 3, 2015
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June
55
Why Jefferson Lab?
Large established user community in the field
CEBAF, the world highest energy SRF linac, as a full energy injector
A Green Field new ion complex and two new collider rings provide
opportunity for a modern design for highest performance
Design meets experimental needs
–
–
–
–
–
Broad CM energy range
Wide range of ion species
Full-acceptance detectors
High luminosity
High polarization
CEBAF
center
IP
IP
Low technical risk
– Design largely based on
conventional technologies
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Richmond,
May 5, 2015
6 3, 2015
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June
CEBAF
66
MEIC
MEIC Design Overview
√s from 15 to 65 GeV: 3 -10 GeV electrons, 20 -100 GeV protons
Polarized light ions (p, d, 3He, Li) & unpolarized light to heavy ions (Au, Pb)
Up to 2 detectors including a full-acceptance primary detector
Luminosity of 1033 to 1034 cm-2s-1 per IP in a broad CM energy range
>70% longitudinal e- polarization & transverse/longitudinal ion polarization
Possibility of upgrade to higher energies and luminosity possible
Cold Ion Collider Ring
(8 to 100 GeV)
PEP-II components
Superferric magnets
Warm Electron
Collider Ring
(3 to 10 GeV)
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Richmond,
May 5, 2015
7 3, 2015
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June
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Design Strategy for High Luminosity
The MEIC design concept for high luminosity is based on high bunch
repetition rate CW colliding beams
KEK-B already reached above 2x1034 /cm2/s
Beam Design
• High repetition rate
• Low bunch charge
• Short bunch length
• Small emittance
IR Design
• Small β*
• Crab crossing
Damping
• Synchrotron
radiation
• Electron cooling
n1n2
n1n2
L f
~f *
 
4 x y
 y
“Traditional” hadrons colliders
• Small number of bunches
• Small collision frequency f
• Large bunch charge n1 and n2
• Long bunch length
• Large beta-star
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Richmond,
May 5, 2015
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June
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Design Strategy for High Polarization
The MEIC design concept for high luminosity is based on
unique figure-8 shape ring structure
– Spin precession in one arc is exactly cancelled in the other
– Zero spin tune independent of energy
– Spin control and stabilization with small solenoids or other compact spin rotators

B

B
Advantages
Efficient preservation of ion
polarization during acceleration
• Energy-independent spin tune
The only practical way to
accommodate polarized deuterons
• Small anomalous magnetic moment
Ease of spin manipulation
• Any desired polarization at IP
• Spin flip
Strong reduction of electron
depolarization due to the
energy independent spin tune
IPAC’15,
Richmond,
May 5, 2015
9 3, 2015
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Group Meeting,
June
99
CEBAF - Full Energy Injector
CEBAF fixed target program
– 5-pass recirculating SRF linac
– Exciting science program beyond
2025
– Can be operated concurrently with
the MEIC
e- collider ring
CEBAF will provide for MEIC
–
–
–
–
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Richmond,
May 5, 2015
10 3, 2015
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June
Up to 12 GeV electron beam
High repetition rate (up to 1497 MHz)
High polarization (>85%)
Good beam quality
10
10
Electron Collider Ring
Beam characteristics
Electron collider ring design
– Circumference of 2154.28 m = 2 x
754.84 m arcs + 2 x 322.3 m straights
– Reuses PEP-II magnets, vacuum
chambers and RF
Arc,
261.7
– 3A beam current up to 6.95 GeV
– Synchrotron radiation power density
10kW/m
– Total power 10 MW
e-
81.7
Future 2nd IP
IP: x,y*=(10,2)cm
Forward e- detection
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Richmond,
May 5, 2015
11 3, 2015
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Group Meeting,
June
11
11
Ion Sources and Linac
QWR
QWR
HWR
4 cryostats
4 cryos
2
2 cryos
1010
cryostats
cryos
RFQ
Ion Sources
IH
MEBT
Optimum lead stripping energy: 13 MeV/u
ABPIS for polarized or un-polarized light ions,
EBIS and/or ECR for un-polarized heavy ions
Linac design based on the ANL linac design.
Pulsed linac capably of accelerating multiple
charge ion species (H- to Pb67+)
– Warm Linac sections (115 MHz)
 RFQ (3 m)
 MEBT (3 m)
 IH structure (9 m)
– Cold Linac sections
 QWR + QWR (24 + 12 m)
 Stripper, chicane (10 m)
 HWR section (60 m)
115 MHz
115 MHz
230 MHz
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Richmond,
May 5, 2015
12 3, 2015
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June
Ion species: p to Pb
Ion species for the reference design
208Pb
Kinetic energy (p, Pb)
285 MeV
100 MeV/u
Maximum pulse current: Light ions
(A/Q<3) Heavy ions (A/Q>3)
2 mA
0.5 mA
Pulse repetition rate
up to 10 Hz
Pulse length: Light ions (A/Q<3)
Heavy ions (A/Q>3)
0.50 ms
0.25 ms
Maximum beam pulsed power
680 kW
Fundamental frequency
115 MHz
Total length
121 m
12
12
Booster
Purpose of Booster
Ekin = 285 MeV – 8 GeV
– Accumulation of ions injected from
Linac
– Cooling
– Acceleration of ions
– Extraction and transfer of ions to the
collider ring
Crossing angle:
75 deg.
7
BETA_X&Y[m] 70
injection
-7
DISP_X&Y[m]
M56  273 cm
0
– Based on super-ferric magnet
technology
– Circumference of 273 m
– Achromatic arcs’ design with partly
negative horizontal dispersion to
minimize momentum compaction to
avoid transition crossing
– Figure-8 shape for preserving ion
polarization
extraction
RF cavity
8 GeV Booster design
0
BETA_XBETA_YDISP_X DISP_Y
Inj. Arc
(2550)
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Richmond,
May 5, 2015
13 3, 2015
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June
272.306
Straight
13
13
Arc
(2550)
Straight (RF +
extraction)
Ion Collider Ring Layout
Ion collider ring design
– match the geometry of PEP-II-component-based electron ring
– Use Super-ferric magnets
 ~3 T maximum field for maximum proton momentum of 100 GeV/c, 4.5 k
operating temperature
 Cost effective construction and operation (factor of ~2 cheaper to operate, GSI)
81.7
Arc, 261.7
Future 2nd IP
ions
IP: x,y*=(10,2)cm
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Richmond,
May 5, 2015
14 3, 2015
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June
14
14
Full-Acceptance Detector
50 mrad crossing angle: improved detection, no parasitic collisions, fast beam separation
Forward hadron detection in three stages
– Endcap
– Small dipole covering angles up to a few degrees
– Far forward, up to one degree, for particles passing
through accelerator quads
Low-Q2 tagger
– Small-angle electron detection
small angle
hadron detection
(from GEANT4)
low-Q2
electron detection
ion quads
large-aperture
electron quads
EM calorimeter
+
TORCH?
n, g
p
e
Fixed
trackers
Thin exit
windows
Endcap
EM calorimeter
e/π threshold
Cherenkov
EM calorimeter
dual-solenoid in common cryostat
4 m coil
RICH
Tracking
FP
~60 mrad bend
central detector
with endcaps
barrel DIRC + TOF
far forward
hadron detection
small-diameter
electron quads
50 mrad beam
(crab) crossing angle
p
IP
1m
1 m Ion quadrupoles
2 Tm
dipole Electron quadrupoles
Trackers and “donut”
calorimeter
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Richmond,
May 5, 2015
15 3, 2015
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June
15
15
Roman pots
Far-Forward Detection Performance
• Neutrals detected in a 25 mrad (total) cone down to zero degrees
 Space for large (> 1 m diameter) Hcal + Emcal
• Excellent acceptance for all ion fragments
• Recoil baryon acceptance:
 up to 99.5% of beam energy for all angles
 down to at least 2-3 mrad for all momenta
 full acceptance for x > 0.005
• Resolution limited only by beam
 longitudinal p/p ~ 310-4
 angular  ~ 0.2 mrad
n, g
2 Tm dipole
20 Tm dipole
p
solenoid
e
• 15 MeV/c resolution for 50GeV/u tagged deuteron beam
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Richmond,
May 5, 2015
16 3, 2015
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Group Meeting,
June
16
16
Multi-Step Electron Cooling
Cooling of ion beams in the MEIC is critical for delivering high luminosity
over a broad CM energy range
2 g
– Help accumulation of positive ions
 cool ~ g
 z 4d
– Reduce the emittance
g
– Maintain the emittance
ion
sources
ion linac
DC
cooler
BB
cooler
Booster
(0.285 to 8 GeV)
Ring
Cooler
Booster
ring
DC
Collider
ring
Bunched
Beam
Cooling
Ion
energy
Electron
energy
GeV/u
MeV
0.11 ~ 0.19
(injection)
0.062 ~
0.1
Emittance reduction
2
1.1
Maintain emittance
during stacking
7.9
(injection)
4.3
Maintain emittance
Up to 100
Up to 55
Function
Accumulation of
positive ions
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Richmond,
May 5, 2015
17 3, 2015
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June
collider ring
(8 to 100 GeV)
ion
bunch
Cooling section solenoid
electron
bunch
energy recovery
SRF Linac
dump
injector
17
17
Ion Polarization in Booster
No special care is needed for ion polarization before the booster
– highly polarized ion source + no polarization loss in the linac
Polarization in Booster stabilized and preserved by a single weak solenoid
– 0.7 Tm at 9 GeV/c
– d / p = 0.003 / 0.01
Longitudinal polarization in the straight with the solenoid
Comparison: Conventional 9 GeV accelerators require B||L of ~30 Tm for protons
and ~110 Tm for deuterons
BIIL
Booster
beam from Linac
to Collider Ring
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Richmond,
May 5, 2015
18 3, 2015
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Group Meeting,
June
18
18
Ion Polarization in Collider Ring
“3D spin rotator” rotates the spin about any chosen direction in 3D and sets the
stable polarization orientation S  (nx , n y , nz )
– Maximum B of 3 T and B|| of 3.6 T => d / p = 0.00025 / 0.01
Spin-control solenoids
Lattice quadrupoles
Radial-field dipoles
Vertical-field dipoles
Placement of 3D spin rotator in the collider ring
Another 3D spin rotator suppresses the zero-integer
spin resonance
ion
IP
IPAC’15,
Richmond,
May 5, 2015
19 3, 2015
JLab Users
Group Meeting,
June
19
19
Electron Polarization
Electron polarization design:
–
–
–
–
–
Vertically polarized (>85%) electron beam from CEBAF
Vertical polarization in the arcs and longitudinal at collision points
Spin rotator for the polarization rotation
Compton polarimeter provides non-invasive continuous measurement of polarization
Average electron polarization reaches above 70%
Polarization Configuration
Magnetic field
Polarization
e-
IP
Laser + Fabry Perot cavity
Photon
calorimeter
Low-Q2 tagger for highenergy electrons
gc
Low-Q2 tagger for
low-energy electrons
Compton Polarimeter
Electron tracking detector
e- beam
Energy (GeV)
3
5
7
9
10
Estimated Pol.
Lifetime (hours)
66
5.2
2.2
1.3
0.8
IP
IPAC’15,
Richmond,
May 5, 2015
20 3, 2015
JLab Users
Group Meeting,
June
20
20
e-p Collision Luminosity
Luminosity (1033 cm-2s-1)
1034 12
A full acceptance detector
1034
10
(baseline)
A high luminosity detector
8
e: 4 GeV
P: 75 GeV
6
4
e: 4 GeV
P: 50 GeV
2
0
1033
e: 4 GeV
P: 30 GeV
20
e: 10 GeV
P: 100 GeV
e: 5 GeV
P: 100 GeV
30
40
50
60
CM energy (GeV)
IPAC’15,
Richmond,
May 5, 2015
21 3, 2015
JLab Users
Group Meeting,
June
21
21
70
Overview of R&D
Prototypes
– Development and testing of 1.2m 3T SF magnets for MEIC ion ring and booster
Collaboration with Texas A&M , FY15-16
– Crab cavity development (collaboration with ODU, leveraging R&D for LHC / LARP crab)
– 952 MHz Cavity development, FY15-17
Design optimization/Modeling
– Optimization of conceptual design of MEIC ion linac
Collaboration with ANL and/or FRIB, FY 15-17
– Optimization of Integration of detector and interaction region design, detector
background, non-linear beam dynamics, PEP-II components
Collaboration with SLAC, FY 12-17
– Feasibility study of an experimental demonstration of cooling of ions using a bunched
electron beam
Collaboration with Institute of Modern Physics, China
– Studies and simulations on preservation and manipulation of ion polarization in a figure8 storage ring
Collaboration with A. Kondratenko, FY 13-15
– Algorithm and code development for electron cooling simulation, FY 15-16
IPAC’15,
Richmond,
May 5, 2015
22 3, 2015
JLab Users
Group Meeting,
June
22
22
Summary and Outlook
MEIC is a ring-ring collider project with mature design
– Luminosities from 1033 up to 1034 cm-2s-1 in a broad CM energy range
– Beam polarizations over 70%
– Low technical risk
MEIC design meets the nuclear physics community requirements
R&D work continues
Cost and performance optimization continues
MEIC design upgradable in energy and luminosity
IPAC’15,
Richmond,
May 5, 2015
23 3, 2015
JLab Users
Group Meeting,
June
23
23
MEIC Collaboration
IPAC’15,
Richmond,
May 5, 2015
24 3, 2015
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June
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