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Transcript of 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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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-
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
© D.Trbojevic
Vert
ical sc
ale
is
incr
ease
d 1
00
fold
30 GeV e-
325 GeV p
Or 125 GeV/u ions
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
€
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
€
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
LHeC
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
Disruption for eRHIC Optimization
β*= 1mEmittance:1nm-rad
β*= 0.2mEmittance:5nm-rad
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010
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
V.N. Litvinenko, ABP Forum, CERN, April 9, 2010