news from erhic and advanced cooling schemes for high energy hadron beams vladimir n. litvinenko for...

News from eRHIC and advanced cooling

schemes for high energy hadron

beams

Vladimir N. Litvinenko for BNL’S eRHIC team and CAD’s AP group

Inputs on Physics from BNL EIC task force, E.-C.Aschenauer, T.Ulrich A.Cadwell, A.Deshpande,

R.Ent, W.Gurin, T.Horn, H.Kowalsky, M.Lamont, T.W.Ludlam, R.Milner, B.Surrow, S.Vigdor,

R.Venugopalan, W.Vogelsang

Inputs on LHC and LHeC from F.Zimmerman, R.Thomas, O.Brüning

Brookhaven National Laboratory, Upton, NY, USA, Stony Brook University, Stony Brook, NY, USA

Center for Accelerator Science and Education

V.N. Litvinenko, ABP Forum, CERN, April 9, 2010

2

Content

• News from eRHIC

• Updates on coherent e-cooling

• How it can be applied for LHC/LHeC

• Conclusions


3

eRHIC Scope -QCD Factory

e-

e+

p

Unpolarized andpolarized leptons4-20 (30) GeV

Polarized light ions (He3) 215 GeV/u

Light ions (d,Si,Cu)Heavy ions (Au,U)50-100 (130) GeV/u

Polarized protons25 50-250 (325) GeV

Electron accelerator RHIC

70% beam polarization goalPositrons at low intensities

Center mass energy range: 15-200 GeV

e-


4

2007 Choosing the focus: ERL or ring for electrons?

• Two main design options for eRHIC:

– Ring-ring:

– Linac-ring:

RHIC

Electron storage ring

RHIC

Electron linear accelerator

Natural staging strategy

✔L x 10

€

L =4πγ hγ e

rhre

⎛

⎝ ⎜

⎞

⎠ ⎟ ξ hξ e( ) σ h

' σ e'

( ) f

€

L = γ h f Nh

ξ hZh

β h*rh

€

ξe >1

€

ξe ~ 0.1


5 MeRHIC is a single IP coolider

4 GeV e x 250 GeV p – 100 GeV/u Au

2 x 60 m SRF linac3 passes, 1.3 GeV/pass

STAR

PHEN

IX

3 pass 4 GeV ERL

Polarized e-gun

BeamdumpM

eRH

IC

detector


4 GeV e x 250 GeV p or 100 GeV/u Au

120m SRF linac3 passes, 1.3 GeV/pass

6

STAR

PHEN

IX

3 pass 4 GeV ERL

Polarized e-gun

Beamdump

M/eRHICdetector

MeRHIC


Integrated low-X IR des ign, β*=25 to50 cm

p, Au

e

Solenoid, 4 T

1T, 3m dipole

1T, 3m dipole

First machine elements 20 m from IP40 m to detect particles scattered at small angles

To provide effective SR protection:-soft bend (~0.05T) is used for final bending of electron beam

© J.Bebee-Wang

40 m

Softdipole

Softdipole

MeRHIC IR

L=3x1033

© E. Aschenauer


eSTAR

ePHEN

IX

Staging all-in tunnel eRHIC: energy of electron beam is increasing

from 5 GeV to 30 GeV by building-up the linacs

2 SRF linac1 -> 5 GeV per pass4 (6) passes

4 to 6 vertically separatedrecirculating passes.# of passes will be chosento optimize eRHIC cost

Coheren

t e-cooler

5 mm

5 mm

5 mm

5 mm

20 GeV e-beam

16 GeV e-beam

12 GeV e-beam

8 GeV e-beam

Com

mon

vacu

um

ch

am

ber

Gap 5 mm total0.3 T for 30 GeV

eRHIC detector

inje

ctor

RHIC: 325 GeV p or 130 GeV/u Au

The mostcost

effective design


eRHIC

eRHIC loop magnets: LDRD project• Small gap provides for low current, low power consumption magnets

• -> low cost eRHIC• Dipole prototype is under tests• Quad and vacuum chamber are in advanced stage

25

cm

Gap 5 mm total0.3 T for 30 GeV

5 mm

20 GeV e-beam

16 GeV e-beam

12 GeV e-beam

8 GeV e-beam

Com

mon

vacu

um

ch

am

ber

0 100 200 300 400 500 600

0.00E+00

2.00E-02

4.00E-02

6.00E-02

8.00E-02

1.00E-01

1.20E-01

1.40E-01

At pole center, longitudinal scan

dx=0mm

Longitudinal Position [mm]

Mag

netic

Fie

ld [T

esla

]

30 32 34 36 38 40 42

0.11

0.112

0.114

0.116

0.118

245Ampere, Transverse scan at center of the dipole

Transverse position [mm]

Mag

neti

c Fi

eld

[Tes

la]

©, G. Mahler, W. Meng, A. Jain, P. He, Y.Hao


ARC

1.27 m beam high

30 GeV e+ ring

30 GeV ERL 6 passes

HE ERL passes

LE ERL passes

30 GeV 25 GeV20 GeV

15 GeV 10 GeV 5 GeV


Linac SS

1.27 m beam highe+ ring

200 m ERL Linac


eRHIC Linac Design

703.75 MHz1.6 m long

Drift 1.5 m long

to DumpE max

Total linac length depend on energyAll cold: no warm-to-cold transition

Based on BNL SRF cavity with fully suppressed HOMs Critical for high current multi-pass ERL

©I. Ben Zvi

©George MahlerInjection

Energy of electron beam is increased in stages by increasing the length of the linacs


TBBU stability (©E. Pozdeyev)

€

x

′ x

⎡

⎣ ⎢

⎤

⎦ ⎥return

=m11 m12

m21 m22

⎡

⎣ ⎢

⎤

⎦ ⎥ ⋅

0

′ x

⎡

⎣ ⎢

⎤

⎦ ⎥comming

Excitation process of transverse HOM

eRHIC

• HOMs based on R. Calaga’s simulations and on recent measurements

• 70 dipole HOM’s to 2.7 GHz in each cavity• Polarization either 0 or 90°• 6 different random seeds • HOM Frequency spread 0-0.001

F (GHz) R/Q (Ω) Q (R/Q)Q

0.8892 57.2 600 3.4e4

0.8916 57.2 750 4.3e4

1.7773 3.4 7084 2.4e4

1.7774 3.4 7167 2.4e4

1.7827 1.7 9899 1.7e4

1.7828 1.7 8967 1.5e4

1.7847 5.1 4200 2.1e4

1.7848 5.1 4200 2.1e4

Threshold significantly exceeds the beam current,especially for the scaled gradient solution.

Simulated BBU threshold (GBBU)

vs. HOM frequency

spread.

50 mA

© I. Ben Zvi

R&D ERLTest-bed for

eRHIC technology

eRHIC – Geometry high-lumi IRwith β*=5 cm, l*=4.5 m

and 10 mrad crossing angleQ5 D5

Q4

90.08703 m

10 mrad4.432 mrad

0.32

878

m

3.6745 mrad

60.0559 m

10 20 30

0.25

573

m25.5735

m

© D.Trbojevic


30 GeV e-

325 GeV p

Or 125 GeV/u ions

Vert

ical sc

ale

is

incr

ease

d 1

00

fold

eRHIC – Geometry of low-x IRwith β*=25 cm, l*=15 m

and 10 mrad crossing angle

0.44

8 m

Q5 D5

Q4

90.0 m

10 mrad 0.32

8 m

3.67 mrad

60.0 m

10 20 30

0.25

5 m25.5 m


© D.Trbojevic

Vert

ical sc

ale

is

incr

ease

d 1

00

fold

30 GeV e-

325 GeV p

Or 125 GeV/u ions

Quads for β*=5 cm

© B.Parker

eRHIC IR1

p /A e

Energy (max), GeV325/13

020

Number of bunches 16674

nsec

Bunch intensity (u) , 1011 2.0 0.24

Bunch charge, nC 32 4

Beam current, mA 420 50

Normalized emittance, 1e-6 m, 95% for p / rms for e

1.2 25

Polarization, % 70 80

rms bunch length, cm 4.9 0.2

β*, cm 25 25

Luminosity, cm-2s-1 2.8x 1033

Luminosity for 30 GeV e-beam operation will be at 20% level

eRHIC IR2

p /A e

325/130

20

16674

nsec

2.0 0.24

32 4

420 50

1.2 25

70 80

4.9 0.2

5 5

1.4 x 1034

Luminosity in eRHIC


Suppression of kink instability

Nonlinear force model with Hourglass effectWith rms proton energy spread =1e-3

By chromaticity: ~ +4

Recent studies proved our early assumption (ZDR Appendix A) that using simple feed-back on electron beam suppress kink instability completely for all eRHIC parameter ranges

© Y. Hao

By feedback

RHIC

ERL

IP

BPM

Feedback kicker


Key ingredients:

RHIC with all its speciesERL technology50 mA polarized electron

gunCoherent electron coolingCrab-crossingHigh gradient SM magnets

* the Gatling gun is the first successful machine gun, invented by Dr. Richard Jordan Gatling.

©J.Skaritka

© E.Tsentalovich, MIT

Main technical challenge is 50 mA

CW polarized gun: we are building two versions

Single large size cathode

Gatling gun


Coherent Electron Cooling (CeC)

Amplifier of the e-beam modulation in an FEL with gain GFEL~102-103

€

RD //,lab =cσ γ

γ 2ωp

<< λ FEL

€

RD⊥ =cγσ θe

ωp

vh

2 RD//

FEL

2 R

D

€

q = −Ze ⋅(1− cosϕ1)

ϕ1 = ωp l1 /cγ

qpeak = −2Ze

FEL

€

LGo =λ w

4πρ 3

€

LG = LGo(1+ Λ)

GFEL = eLFEL / LG

€

Δϕ =LFEL

3LG

€

cΔt = −D ⋅γ − γ o

γ o

; D free =L

γ 2; Dchicane = lchicane ⋅θ

2.......

€

kFEL = 2π /λ FEL; kcm = kFEL /2γ o

€

Δϕ =4πen ⇒ ϕ = −ϕ 0 ⋅cos kcmz( )r E = −

r ∇ϕ = −ˆ z Eo ⋅X sin kcmz( )€

namp = Go ⋅nk cos kcmz( )

€

A⊥ =

2πβ⊥εn /γ o

€

qλFEL≈ ρ(z)

0

λFEL

∫ cos kFELz( )dz

ρ k = kq(ϕ1); nk =ρ k

2πβε⊥

Ez

€

ΔEh = −e ⋅Eo ⋅ l2 ⋅sin kFELDE − Eo

Eo

⎛

⎝ ⎜

⎞

⎠ ⎟⋅

sinϕ 2

ϕ 2

⎛

⎝ ⎜

⎞

⎠ ⎟⋅ sin

ϕ1

2

⎛

⎝ ⎜

⎞

⎠ ⎟2

⋅Z ⋅X; Eo = 2Goeγ o /βε⊥n

€

ω p t

€

−q /Ze

FEL

E0

E < E0

E > E0

Modulator

Kicker

Dispersion section ( for hadrons)

Electrons

Hadrons

l2l1 High gain FEL (for electrons)

Eh

E < Eh

E > Eh

DispersionAt a half of plasma oscillation

Debay radii

€

RD⊥ >> RD //

€

ωp = 4πnee2 /γ ome

Density

€

ω p t

€

λ fel = λ w 1+r a w

2( ) /2γ o

2

€

ra w = e

r A w / mc2

€

Eo = 2Goγ o

e

βε⊥n

€

X = q / e ≅ Z(1− cosϕ1) ~ Z


Possible layout in RHIC IPof CeC driven by a single linac

for RHIC and eRHIC

Gun 1Gun 2

Beam dump 1 Beam dump 2ERL dual-way electron linac2 Standard eRHIC modules

Ep, GeV g Ee, MeV

100 106.58 54.46

250 266.45 136.15325 346.38 177.00

Modulator for Blue Modulator for YellowFEL for Blue

FEL for Yellow

Kicker for BlueKicker for Yellow


€

X =εx

εxo

; S =σ s

σ so

⎛

⎝ ⎜

⎞

⎠ ⎟

2

=σ E

σ sE

⎛

⎝ ⎜

⎞

⎠ ⎟

2

;

dX

dt=

1

τ IBS⊥

1

X 3 / 2S1/ 2−

ξ⊥

τ CeC

1

S;

dS

dt=

1

τ IBS //

1

X 3 / 2Y−

1− 2ξ⊥

τ CeC

1

X;

€

εxn 0 = 2μm; σ s0 =13 cm; σ δ 0 = 4 ⋅10−4

τ IBS⊥ =4.6 hrs; τ IBS // =1.6 hrs

IBS in RHIC foreRHIC, 250 GeV, Np=2.1011

Beta-cool, A.Fedotov

€

εx n = 0.2μm; σ s = 4.9 cm

This allows a) keep the luminosity as it is b) reduce polarized beam current down to

50 mA (10 mA for e-I)c) increase electron beam energy to 20

GeV (30 GeV for e-I)d) increase luminosity by reducing * from

25 cm down to 5 cm

Dynamics:Takes 12 minsto reach stationarypoint

€

X =τ CeC

τ IBS //τ IBS⊥

1

ξ⊥ 1− 2ξ⊥( ); S =

τ CeC

τ IBS //

⋅τ IBS⊥

τ IBS //

⋅ξ⊥

1− 2ξ⊥( )3

Gains from coherent e-cooling: Coherent Electron Cooling vs. IBS


Layout for Coherent Electron Cooling proof-of-principle experiment in RHIC IR

Collaboration is opened for all interested labs/people

DX DX19.6 m

Modulator, 4 mWiggler 7mKicker, 3 m

20 MeV SRF linacBea

m

dum

p

Parameter

Species in RHIC Au ions, 40 GeV/u

Electron energy 21.8 MeV

Charge per bunch 1 nC

Train 5 bunches

Rep-rate 78.3 kHz

e-beam current 0.39 mA

e-beam power 8.5 kW

26



Polarizing Hadron Beams with Coherent Electron Cooling

New LDRD proposal at BNL: VL & V.Ptitsyn

Modulator

Kicker

Delay for hadrons

Electrons

Hadrons

l2High gain FEL (for electrons)

HW1left

helicity

HW2right

helicity

Modulation of the electron beam density around a hadron is caused by value of spin component along the longitudinal axis, z. Hardons with spin projection onto z-axis will attract electrons while traveling through helical wiggler with left helicity and repel them in the helical wiggler with right helicity.

The high gain FEL amplify the imprinted modulation.

Hadrons with z-component of spin will have an energy kick proportional to the value and the sigh if the projection. Placing the kicker in spin dispersion will result in reduction of z-component of the spin and in the increase of the vertical one.

€

dr n / dγ

This process will polarize the hadron beam

Polarizing Hadron Beams with Coherent Electron Cooling

• It is very provocative proposal and requires very high gain FELs for attaining reasonable spin-cooling times – no time to go into many details

• For LHC this technique could an unique opportunity to operate with polarized hadrons

• in RHIC, bringing polarization of proton beams close to 100% would provide for a nearly eight-fold boost of the observables and could be of critical for solving long-standing proton spin crisis

• The methods can be used for polarizing other hadrons, such as deuterons – polarization of which is considered to be impossible in RHIC, He3 and other ions

• The technique can open a unique possibility of getting polarized antiprotons


Coherent-electron-Cooling would provide following for linac-ring

LHeC• Smaller proton beam emittance down to 0.2 mm mrad

• Can provide shorted bunches down to 1 cm (if needed)

• Allows to reduce electron beam current 20-fold to achieve of e-p luminosity above 1034 level with 60 GeV electrons and 7 TeV protons


Sample of CeC for LHeC

LHC Cooling time

Circumference 26658.883 m Full bunch 0.346 hrs

Main Parameters CeC Local 176.27 sec

Modulator Length 70 m Length of the system 153.70 m

Kicker length 35 m FEL length 48.70 m

Peak current, e 100.0 A FEL gain length 3.08 m

Amplification 1000.00

Wavelength 10 nm FEL formula TRUElw 5 cm Checks TRUE

FEL bandwidth 0.02

I will use conservative 0.8 hrs cooling time


€

X =εx

εxo

; S =σ s

σ so

⎛

⎝ ⎜

⎞

⎠ ⎟

2

=σ E

σ sE

⎛

⎝ ⎜

⎞

⎠ ⎟

2

;

dX

dt=

1

τ IBS⊥

1

X 3 / 2S1/ 2−

ξ⊥

τ CeC

1

S;

dS

dt=

1

τ IBS //

1

X 3 / 2S1/ 2−

1− 2ξ⊥

τ CeC

1

X;

Evolution of beam in LHC at 7 TeV(assuming nominal LHC bunch intensity 1.15e11 p/bunch and 40% of CeC cooling capability)

€

εxn 0 = 3.75μm; σ s0 = 7.55cm

τ IBS⊥ = 80 hrs; τ IBS // =61 hrs €

σε2

τ IBS //

=Nrc

2c

25πγ 3εx3 / 2σ s

f χ m( )β yv

; εx

τ IBS⊥

=Nrc

2c

25πγ 3εx3 / 2σ s

H

β y1/ 2 f χ m( ) ;κ =1

f χ m( ) =dχ

χχ m

∞

∫ lnχ

χ m

⎛

⎝ ⎜

⎞

⎠ ⎟e

−χ ; χ m =rcm

2c 4

bmaxσ E2 ;bmax ≅ n−1/ 3; rc =

e2

mc 2; (e− > Ze;m− > Am)

IBS rates in LHC from

Table 2.2

€

X =τ CeC

τ IBS //τ IBS⊥

1

ξ⊥ 1− 2ξ⊥( ); S =

τ CeC

τ IBS //

⋅τ IBS⊥

τ IBS //

⋅ξ⊥

1− 2ξ⊥( )3

Stationary solution for τCeC = 0.8 hrs

€

εx n = 0.19μm; σ s = 0.87 cm

J.LeDuff, "Single and Multiple Touschek effects", Proceedings of CERN Accelerator School, Rhodes, Greece, 20 September - 1 October, 1993, Editor: S.Turner, CERN 95-06, 22 November 1995, Vol. II, p. 573


Layout for ERL based LHC

• Hadrons – 1.15e11 per bunch– Cooled by CeC

• Electron– Accelerated in the ERL - 60 GeV– Polarized electron beam current - 8

mA

• Number of passes – 3• AC power consumption – 100 MW• Crab-crossing• β*=12 cm• L = 2.1034 cm-2 sec-1

R=700mR=700m

10 GeV linac

10 GeV linac

0.5 GeVERL-injector

DumpGun


Conclusions

• We focused again of all-in-the-tunnel staging of eRHIC

• In addition to previous solid design of low-X IR, we had developed high luminosity IR with L >1034 using advances in the SM quad technology and in the crab-crossing

• We aggressively pursue development of polarized Gatling gun and develop specific plans for testing Coherent Electron Cooling at RHIC

• Using eRHIC-style ERL and CeC for 60 GeV x 7 TeV LHeC promises providing L >1034 with power consumption below 100 MW and modest size of facility


Back-up


LHeC


Radius, r Cryo RF main RF SR Magnets Total Passes500.00 MW 2 x 7.5 GeV linacs 18.56 16.67 60.25 4 99.48 42 x10 GeV linacs 24.75 22.22 46.08 3 96.05 32 x 15 GeV linacs 37.13 33.33 32.40 2 104.86 230 GeV linac, dogbone 37.13 33.33 48.17 3 121.63 DGBN

LHC protonsEnergy 7 TeVg_p 7.46E+03N_p 1.70E+11

No CoolingEmittance, norm 3.75 mm mrad

Emittance 5.03E-01 nm radAllowable tune shift 0.01

Maximum # of e 3.07E+11Rep-rate 2.00E+07 Hz

I max 9.84E-01 ARealistic 0.008 A

N real 2.50E+09Room for improvement 1.23E+02

b* 0.12 m4pbe 7.58E-10 m^2L/h 1.12E+33

With coolingEmittance, norm 0.2 mm mrad

Emittance 2.68E-02 nm radAllowable tune shift 0.01

Maximum # of e 1.64E+10Rep-rate 2.00E+07 Hz

I max 5.25E-02 ABeam current 0.008 A

N real 2.50E+09Room for improvement 6.56E+00

b* 0.12 m4pbe 4.04E-11 m^2L/h 2.10E+34

©Dejan Trbojevic

Integrated h igh- Q IR des ign, β*=5cm First quadrupole is 4.5 m from IP

Plan to use newly commissioned (last month!) LARP SC quads with 200 T/m gradient

Nb3Sn

May be used fo r luminos i ty hungry exper imentsWi l l work w i th the

A lan Ca ldwe l l de tec to rOr a J Lab type one

L=1.4x1034


Additional advantage of linac-ring – removing systematic errors

It is built-in feature of the linac-ring eRHIC: we can arbitrary select polarization of individual bunches

a) In RHIC this is already implemented by injection scheme (ion source) for protons

b) In eRHIC ERL electron polarization is reversible by switching helicity of the laser photons

protonselectrons

It is impossible in ring-ring EIC

© D. Lowenstein


Disruption for eRHIC Optimization

β*= 1mEmittance:1nm-rad

β*= 0.2mEmittance:5nm-rad


Incorporating eSTAR and ePHENIX

• Without changing DX-D0 both the energy and luminosity will be low in electron-hadron collisions

• Parallel operation of hadron-hadron and electron-hadron collisions does not allow cooling of hadron beam, hence 10-fold lower luminosity for e-p and e-A

• Sequential operation of RHIC as a hadron collider and as an electron-hadron collider allows to have both full energy and full luminosities in al modes of operation, including coherent electron cooling

• Coherent Electron Cooling would provide 10-fold increases in e-p amd e-A luminosities (and 6-fold increase in polarized p-p luminosity)

• We have designs of two IR: low-x (L~3.1033) and high-lumi (L~2.1034)

• We suggest using crossing angle and ±5 mrad crab-cavities to have identical energy-independent geometry of IRs and no synchrotron radiation in detectors


news from erhic and advanced cooling schemes for high energy hadron beams vladimir n. litvinenko for...

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