Ion Collider Ring Design V.S. Morozov for MEIC study group MEIC Collaboration Meeting, JLab October...

Ion Collider Ring Design

V.S. Morozov for MEIC study group

MEIC Collaboration Meeting, JLab

October 5-7, 2015

22December 18 2014

2MEIC Collaboration Meeting, JLab, October 5-7, 2015 2

Provide the necessary beam parameters' 20(8)-100 GeV protons, 12-40 GeV/u ions' Focusing at the IP that supports luminosities above 1033 cm-2s-1

' Sufficient beam and luminosity lifetime

Capability of operating multiple detectors' One full-acceptance detector incorporated

Small angle detection' Space for a second detector reserved

Polarization preservation and control using figure-8 geometry' Light ion (p, d, 3He, and possibly Li) polarization above 70%' Transverse and longitudinal polarization orientations adjustable at the IP' Sufficient polarization lifetime

Match the electron collider ring geometry' Same tunnel

Incorporate provisions for non-linear dynamics correction' Sextupole families' Chromatic correction scheme

Ion Collider Design Requirements

33December 18 2014


Figure-8 ring with a circumference of 2153.9 mTwo 261.7 arcs connected by two straights crossing at 81.7

Ion Collider Ring

R = 155.5 m

Arc, 261.7

IPdisp. supp./

geom. match #3disp. supp./

geom. match #1

disp. s

upp./

geom. match

#2disp. supp./

geom. match #3

det. elem.

disp. s

upp.

norm.+SRF

tune

tromb.+

match

beam exp./

match

elec. co

ol.

ions

81.7future 2nd IP

Polarimeter

44December 18 2014


Ion Collider Ring Parameters

Circumference m 2153.89

Straights’ crossing angle deg 81.7Horizontal / vertical beta functions at IP *

x,y cm 10 / 2Maximum horizontal / vertical beta functions x,y max m ~2500Maximum horizontal dispersion Dx m 3.28Horizontal / vertical betatron tunes x,y 24(.38) / 24(.28)Horizontal / vertical natural chromaticitiesx,y -101 / -112

Momentum compaction factor 6.45 10-3 Transition energy tr 12.46Normalized horizontal / vertical emittance x,y µm rad 0.35 / 0.07Horizontal / vertical rms beam size at IP *

x,y µm ~20 / ~4Maximum horizontal / vertical rms beam size x,y mm 2.8 / 1.3

All design goals achieved

Resulting collider ring parameters

Proton energy range GeV 20(8)-100Polarization % > 70Detector space m -4.6 / +7Luminosity cm-2s-1 > 1033

55December 18 2014


Basic building block of the arcs' Length of 22.8 m = 1.5 electron FODO cell lengths (26 cells per arc)' Betatron phase advance of 90 in each plane

Dipoles' Magnetic/physical length of 8/8.28 m (implemented as two 4 m long pieces)' Bending angle of 73.3 mrad (4.2), bending radius of 109.1 m, sagitta of 18.3 mm' Field of 3.06 T at 100 GeV/c' x aperture = (4 cm+sagitta/2) = 5 cm, y aperture = 3 cm (10 + 1 cm orbit

allowance)

Quadrupoles' Magnetic/physical length of 0.8/0.9 m' Field gradients of 52.7/-52.9 T/m at 100 GeV/c' Field of 2.1/-2.1 T at 40 mm radius

Sextupole/corrector package next to each quadrupole

' Magnetic/physical length of 0.5/0.6 m' 3 T at 40 mm focusing sextupole adds

34.8/-7.1 units of x/y chromaticity' 3 T at 40 mm defocusing sextupole adds

-3.7/18.1 units of x/y chromaticity

BPM next to each quadrupole' Physical length of 0.15 m

Arc FODO Cell

66December 18 2014


MEIC Super-Ferric Dipole

2 x 4 long dipole

NbTi cable

3 T

Correction sextupole

Common cryostat

talks by P. McIntyre and A.D. Kovalenko

77December 18 2014


Provide dispersion suppression and geometric match to the electron ringArc end upstream of IP

' Shaped to provide 50 mrad crossing angle at the IP

Arc end downstream of IP' Shaped to provide 1.5 m separation from the electron beam

Arc Ends

ions IP

20 m

5 m

ions

10 m

2 m

88December 18 2014


Detector IntegrationFully-integrated detector and interaction region design that meets:

– Detector requirements: full acceptance and high resolution

– Beam dynamics requirements: consistent with non-linear dynamics requirements

– Geometric constraints: matched collider ring footprints

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

talks at the Detector & Interaction Region Sessions

concept by P. Nadel-Turonski,R. Ent, and C. Hyde

99December 18 2014


IR design features' Modular design' Based on triplet Final Focusing Blocks (FFB)' Asymmetric design to satisfy detector requirements and reduce chromaticity' Spectrometer dipoles before and after downstream FFB, second focus downstream of IP' No dispersion at IP, achromatic optics downstream of IP

Ion IR Optics

IP

ions

match/beam expansion FFB FFB

detectorelements

geom. match/disp. suppression

match/beam compression

*,

,

10 / 2 cm

18 / 3.6 μm

x y

x y

1010December 18 2014


Space reserved for two 30 m long cooling solenoids in one straight' Solenoids of opposite fields for coupling compensation and polarization dynamics

Electron Cooling Section

ions

cooling solenoid matchcooling solenoidmatch



Bunched Beam Electron Cooler

Baseline cooling requirements – Emittance 0.5 to 1 mm-mrad -> reduce IBS effect– Magnetized beam, up to 55 MeV energy, 200 mA current– Linac for acceleration– Must utilize energy-recovery-linac (beam power is 11 MW)

Solution : cooling by a bunched electron beam

ion bunch

electron bunch

Cooling section solenoid

SRF Linacdumpinjector

energy recovery

Electron energy MeV up to 55

Current and bunch charge A / nC 0.2 / 0.42

Bunch repetition MHz 476

Cooling section length m 60

RMS Bunch length cm 3

Electron energy spread 10-4 3

Cooling section solenoid field T 2

Beam radius in solenoid/cathode mm ~1 / 3

Solenoid field at cathode KG 2

talks at the Beam Cooling Sessions



Two FODO cells with matching sections for betatron tune control' One of the matching sections shared with electron cooling section

Tune Trombone

ions

match2 FODOmatch



Filled with FODOMatching geometry of arc endsRF placed between FODO quadrupoles

Second Straight without IR

ions

matchFODOmatchRF

talk by R. Rimmer



Optics of a complete ring with all sections incorporated and matched

Complete Ion Collider Ring Lattice

ions

Arc 1Straight 2

IP

Arc 2Straight 1Arc 1



Nonlinear Dynamics: Ion RingExplored multiple compensation schemes –I sextupoles pairs in the arcs

– Compensate chromatic smear at the IP– Compensate residual linear chromaticity with additional sextupoles

-1.5 -1 -0.5 0 0.5 1 1.50

0.2

0.4

0.6

0.8

1

1.2

1.4

x (mm)

y (

mm

)

Dynamic aperture

p/p = 0.0 p/p = 0.1% p/p = 0.2% p/p = 0.3% p/p = 0.4%(- 8p/p , + 13p/p)

At p/p = 0.3%

(- 40x , + 40x)

(- 40y , + 40y)

IP work and talks by Y. Nosochkov and M.-H. Wang of SLAC and G. Wei of JLabwith a lot of help from D. Trbojevic, W. Guo, and Y. Jing of BNL



Ion PolarizationFigure-8 design

– Zero spin tune independent of energy: spin precession in one arc is cancelled in the other– Spin control and stabilization with small solenoids or other compact spin rotators

Spin tracking in progress– figure-8 with an error

2 T 2 m control solenoids can stabilize proton and deuteron spins up to 100 GeV

B

B

no stabilization stabilization by 1 solenoid

talk by A.M. Kondratenko



Crab CrossingRestores effective head-on collisions with 50 mrad crossing angle

– Luminosity preserved

Deflective crabbing technology (demonstrated at KEK-B)– Transverse electric field of SRF cavities

Local crabbing scheme– One set of cavities upstream of IP next to FFB– Another set of cavities(n+1/2) downstream of IP

IPe-

ions

crab cavities

crab cavities

talks by A. Castilla and J. Delayen



Design of the baseline ion collider ring completed

All design requirements met Beam parameters: 20(8)-100 GeV protons, luminosity > 1033 cm-2s-1

One full-acceptance detector integrated, room for a second detector reserved High polarization (>70%) adjustable to any orientation using figure 8 geometry Electron ring geometry matched Non-linear correction scheme developed and provisions for it incorporated into lattice

Ongoing and future work– Design optimization– Non-linear dynamics correction– Error sensitivity studies– Integration of remaining components

• Detector solenoid and compensation• Crab cavities• Vertical doglegs

Current Status & Outlook



Backup



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

Full-Acceptance Detector

R. Ent, C.E. Hyde, P. Nadel-Turonski



Detector Region Layout

e-

ions

IP

forward iondetection

forward e-

detection

FFQsFFQs



One straight contains an IRThe other straight filled with FODO

Layouts of Two Straights



Dipoles: 133' 127 super-ferric, B < 3.06 T' 2 special-design for IR + 4 cos() super-conducting, B < 4.7 T

Quadrupoles: 205' 155 with integrated field < 48 T' 44 with integrated field < 72 T' 6 special-design final-focusing quadrupoles

Sextupoles: 125' Maximum pole-tip field ~1.5 T

Correctors: 197' Each combines x/y kicker, skew quad and higher-order multipoles

BPMs: 197RF: 20 m of normal and 20 m of SC (talk by R. Rimmer)Special elements (talk by L. Harwood)

' Injection kicker' Abort system' Electron cooler solenoids' Spin control elements: short solenoids and dipoles' Polarimeter' Crab cavities' Collimators' Detector solenoid compensating elements

Basic Element Count

Ion Collider Ring Design V.S. Morozov for MEIC study group MEIC Collaboration Meeting, JLab October...

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