vasiliy morozov on behalf of meic study group jlab users group meeting, june 3, 2015 status of...

Vasiliy Morozov on behalf of MEIC Study GroupJLab Users Group Meeting, June 3, 2015

Status ofMedium-energy Electron Ion Collider (MEIC)

Design

22IPAC’15, Richmond, May 5, 2015 22JLab Users Group Meeting, June 3, 2015 2

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


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


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


EIC Physics HighlightsAn 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


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

Low technical risk– Design largely based on

conventional technologiesCEBAF

MEICIPIP

CEBAF center


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

Warm ElectronCollider Ring(3 to 10 GeV)

Ion Source

Bo

ost

er

Linac

Cold Ion Collider Ring(8 to 100 GeV)

Superferric magnets

PEP-II components


Design Strategy for High LuminosityThe MEIC design concept for high luminosity is based on high bunch repetition rate CW colliding beams

Beam Design• High repetition rate• Low bunch charge • Short bunch length• Small emittance

IR Design• Small β*• Crab crossing

Damping• Synchrotron radiation

• Electron cooling

“Traditional” hadrons colliders• Small number of bunches• Small collision frequency f• Large bunch charge n1 and n2

• Long bunch length• Large beta-star

1 2 1 2*

~4 x y y

n n n nL f f

KEK-B already reached above 2x1034 /cm2/s


Design Strategy for High PolarizationThe 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

Efficient preservation of ion polarization during acceleration• Energy-independent spin tune

Ease of spin manipulation• Any desired polarization at IP

• Spin flip

The only practical way to accommodate polarized deuterons• Small anomalous magnetic moment

Strong reduction of electron depolarization due to the energy independent spin tune

Advantages


CEBAF - Full Energy Injectore- collider ringCEBAF fixed target program

– 5-pass recirculating SRF linac– Exciting science program beyond

2025– Can be operated concurrently with

the MEIC

CEBAF will provide for MEIC– Up to 12 GeV electron beam– High repetition rate (up to 1497 MHz)– High polarization (>85%)– Good beam quality


Electron Collider Ring

e-

R=155m

RF RF

Spin rotator

Spin rotator

CCB

Arc, 261.7 81.7

Forward e- detection

IP: x,y*=(10,2)cm

Tune trombone &

Straight FODOs

Future 2nd IP

Spin rotator

Spin rotator

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

Beam characteristics– 3A beam current up to 6.95 GeV– Synchrotron radiation power density

10kW/m– Total power 10 MW


Ion Sources and Linac

Optimum lead stripping energy: 13 MeV/u

10 cryostats4 cryostats 2Ion Sources

QWRQWR HWR

IH

RFQ

MEBT

10 cryos4 cryos 2 cryos

Ion species: p to Pb

Ion species for the reference design 208Pb

Kinetic energy (p, Pb)285 MeV100 MeV/u

Maximum pulse current: Light ions (A/Q<3) Heavy ions (A/Q>3)

2 mA0.5 mA

Pulse repetition rate up to 10 Hz

Pulse length: Light ions (A/Q<3)Heavy ions (A/Q>3)

0.50 ms0.25 ms

Maximum beam pulsed power 680 kW

Fundamental frequency 115 MHz

Total length 121 m

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) 115 MHz Stripper, chicane (10 m) 115 MHz HWR section (60 m) 230 MHz


Booster

Purpose of Booster– Accumulation of ions injected from

Linac– Cooling – Acceleration of ions– Extraction and transfer of ions to the

collider ring

8 GeV Booster design – 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

extractionRF cavity

Crossing angle:

75 deg.

Ekin = 285 MeV – 8 GeV

injection

272.3060

700

7-7

BE

TA

_X&

Y[m

]

DIS

P_X

&Y

[m]

BETA_XBETA_YDISP_X DISP_Y

Straight Inj. Arc (2550)

Straight (RF + extraction)

Arc (2550)

56 273M cm


Ion Collider Ring Layout

IP: x,y*=(10,2)cmdisp. supp./

geom. match disp. supp. /

geom. match

det. elem.

norm.+SRF

tune

tromb.+

matchelec. cool.

ions

81.7

disp. supp. /

geom. matchdisp

. supp. /

geom. match

Future 2nd IP

R=155m

Arc, 261.7

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)


Full-Acceptance Detector50 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

far forwardhadron detectionlow-Q2

electron detection large-apertureelectron quads

small-diameterelectron quads

central detector with endcaps

ion quads

50 mrad beam(crab) crossing angle

n,

ep

p

small anglehadron detection

~60 mrad bend

(from GEANT4)

2 Tm dipole

Endcap Ion quadrupoles

Electron quadrupoles

1 m1 m

IP FP

Roman potsThin exit windows

Fixed trackers

Trackers and “donut” calorimeter

RICH+

TORCH?

dual-solenoid in common cryostat4 m coil

barrel DIRC + TOF

EM

ca

lori

met

er

EM calorimeter

Tracking

EM

ca

lori

met

er

e/π

th

res

ho

ldC

he

ren

ko

v


Far-Forward Detection Performance

e

p

n, 20 Tm dipole

2 Tm dipole

solenoid

• 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 ~ 310-4

angular ~ 0.2 mrad

• 15 MeV/c resolution for 50GeV/u tagged deuteron beam


Multi-Step Electron Cooling

ion sources ion linac

Booster (0.285 to 8 GeV)

collider ring(8 to 100 GeV)

BB cooler

DC cooler

Ring Cooler FunctionIon

energyElectron energy

GeV/u MeV

Booster ring

DC

Accumulation of positive ions

0.11 ~ 0.19

(injection)

0.062 ~ 0.1

Emittance reduction 2 1.1

Collider ring

Bunched Beam

Cooling

Maintain emittance during stacking

7.9 (injection)

4.3

Maintain emittance Up to 100 Up to 55

ion bunch

electron bunch

Cooling section solenoid

SRF Linacdumpinjector

energy recovery

Cooling of ion beams in the MEIC is critical for delivering high luminosity over a broad CM energy range– Help accumulation of positive ions– Reduce the emittance– Maintain the emittance

dzcool 42~


Ion Polarization in BoosterNo 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

beam from Linac

Booster

to Collider Ring

BIIL


Ion Polarization in Collider Ring“3D spin rotator” rotates the spin about any chosen direction in 3D and sets the stable polarization orientation

– Maximum B of 3 T and B|| of 3.6 T => d / p = 0.00025 / 0.01

( , , )x y zS n n n

Placement of 3D spin rotator in the collider ring

Another 3D spin rotator suppresses the zero-integer

spin resonance

Spin-control solenoids

Vertical-field dipolesRadial-field dipoles

Lattice quadrupoles

3D Spin

Rotator

IPion


Electron PolarizationElectron 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%

IP

Spin Rotator

e-

Magnetic field

Polarization

Energy (GeV) 3 5 7 9 10

Estimated Pol. Lifetime (hours)

66 5.2 2.2 1.3 0.8

Polarization Configuration

c

Laser + Fabry Perot cavity

e- beam

Low-Q2 tagger for low-energy electrons

Low-Q2 tagger for high-energy electrons

Electron tracking detector

Photon calorimeter

IP

Compton Polarimeter


e-p Collision Luminosity

1034

1033

e: 5 GeVP: 100 GeV

e: 10 GeVP: 100 GeV

e: 4 GeVP: 30 GeV

e: 4 GeVP: 75 GeV

e: 4 GeVP: 50 GeV


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 componentsCollaboration with SLAC, FY 12-17

– Feasibility study of an experimental demonstration of cooling of ions using a bunched electron beamCollaboration with Institute of Modern Physics, China

– Studies and simulations on preservation and manipulation of ion polarization in a figure-8 storage ringCollaboration with A. Kondratenko, FY 13-15

– Algorithm and code development for electron cooling simulation, FY 15-16


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


MEIC Collaboration

vasiliy morozov on behalf of meic study group jlab users group meeting, june 3, 2015 status of...

Documents

context meic design

design strategies

modern design

meic design overview

electronion collider

highest performance

final design optimizations

meic timeline