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C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
CLIC e+ sources statusL. Rinolfi
with contributions from
F. Antoniou, H. Braun, A. Latina, Y. Papaphilippou, F. Zimmermann / CERN
R. Chehab / IPNL/IN2P3 - Lyon, V.M.Strakhovenko / BINP - Novosibirsk
A. Variola, A. Vivoli / LAL - Orsay, A. Ferrari / Uppsala University
E. Buylak, P. Gladkikh / NCS / KIPT - Kharkov
W. Gai, W. Liu / ANL, J. Sheppard / SLAC
T. Kamitani, T. Omori / KEK, M. Kuriki / Hiroshima University
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
The CLIC Injector complex in 2008
e- gun
3 TeV
Base line configuration
LaserDC gunPolarized e-
Pre-injector Linac for e-
200 MeV
e-/Target
Pre-injector Linac for e+
200 MeV
Primary beam Linac for e-
5 GeV
Inje
ctor
Lin
ac
2.2
GeV
e+ DR
e+ PDR
Boo
ster
Lin
ac
6.6
GeV 4 GHz
e+ BC1 e- BC1
e+ BC2 e- BC2e+ Main Linac e- Main Linac
12 GHz, 100 MV/m, 21 km 12 GHz, 100 MV/m, 21 km
2 GHz
e- DR
e- PDR
2 GHz 2 GHz 2 GHz
4 GHz 4 GHz
12 GHz 12 GHz
9 GeV48 km
30 m 30 m
2.424 GeV 2.424 GeV
e
Target
AMD
2.424 GeV365 m 2.424 GeV
365 m
473 m
228 m
365 m 365 m
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
NLC
(1 TeV)
CLIC 2008
(3 TeV)
ILC
(Nominal)
Energy E GeV 8 9 15
Bunch population N 109 7.5 3.72 - 4 20
Nb bunches / train nb- 190 312 2625
Bunch spacing tbns 1.4 0.5
(6 RF periods)
369
Train length tpulsens 266 156 968625
Emittances x , ynm, nm.rad 3300, 30 600, 10 8400, 24
rms bunch length zm 90-140 43 - 45 300
rms energy spreadE 0.68
(3.2 % FW)1.5 - 2 1.5
Repetition frequency frepHz 120 50 5
Beam power P kW 219 90 630
Main beam parameters comparison
At the entrance of the Main Linac for e- and e+
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
# of bunches per pulse
# of positrons per bunch
# of positrons per pulse
Total charge
(nC)
Current
(A)
Exit of BC2
= Entrance of Main Linac
( 9 GeV)
312 4 x 109 1. 24x1012 200 1.3
At exit Pre- Damping ring
(2.424 GeV) 312 4.4 x 109 1.37 x 1012 220 1.4
At exit Injector Linac
(2.424 GeV) 312 6.4 x 109 2 x 1012 319 2
At exit Pre- Injector Linac
(200 MeV) 312 6.7 x 109 2.1 x 1012 334 2.1
Assuming ~ 90 % efficiency between the PDR and the Main Linac
CLIC parameters relevant for e+ source
Repetition frequency 50 Hz
Total pulse length 156 nsAssuming ~ 70 % capture efficiency in the PDR
Assuming ~ 95 % efficiency between the Pre-Injector and the Injector Linac
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Conventional e+ source based on channelling
A e- beam impinges on the crystal: - energy of 5 GeV - beam size of 2.5 mm
crystalamorphous
e-
e-
e+
Yield: 0.9 e+ / e-
@ 200 MeV
R. Chehab, V. Strakovenko, A. Variola, A. Vivoli / LAL
•A crystal e+ source :• - a 1.4 mm thick W crystal oriented along <111> axis• - a 10 mm thick W amorphous disk
•Charged particles are swept off after the crystal:only (> 2MeV) impinge on the amorphous target.
• The distance between the 2 targets is 2 meters.
e-
e+
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
CLIC Channeling e+ source
Parameter Unit CLIC
Primary e- Beam
Energy GeV 5
N e- /bunch 109 7.5
N bunches / pulse - 312
N e- / pulse 1012 2.34
Pulse length ns 156
Repetition frequency Hz 50
Beam power kW 94
Linac frequency GHz 2
Beam radius (rms) mm 2.5
Bunch length (rms) mm 0.3
Parameter Unit
Target Crystal Amorph.
Material W W
Length mm 1.4 10
Beam power deposited
kW 0.2 7.5
Deposited P / Beam Power
% 0.2 8
Pulse energy density
1012 GeV/mm2 0.6 -
Energy lost per volume
109 GeV/mm3 0.8 1.9
Peak energy deposition
density (PEDD)J/g 6.8 15.5
Yield (at 200 MeV): 0.9 e+ / e-
Experimental limit found at SLAC: PEDD = 35 J/g
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Beam parameters with channeling
Positrons after capture section at 270 MeV
Parameter Unit CLIC
Energy (E) GeV 0.270
No. of e+ / bunch (N) 109 6.7
Bunch length (rms) mm 8
Energy Spread (rms) % 5
Longitudinal emittance (l) eV.m 105
Horizontal emittance (x) / (x) mm. mrad 12 / 6300
Vertical emittance (y) / (y) mm. mrad 12 / 6300
Q ~ 1 nC
See R. Chehab talk at this workshop
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Parameter UnitConventional target
CERN simulations
Channeling
LAL simulations
Energy (E) GeV 0.200 0.270
No. of e+ / bunch (N) 109 6.7 6.7
Bunch length (rms) mm 5 8
Energy Spread (rms) % 3.5 5
Horizontal emittance (x) mm. mrad 9200 6300
Vertical emittance (y) mm. mrad 9200 6300
Beam parameters comparison
Accelerating gradient MV/m 15 18
Positrons after capture section at the end of the pre-injector linac
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Longitudinal phase space at 2.4 GeV
Energy spread = 65 MeV
p/p (rms) = 2.7 %
If PDR acceptance is
p/p = ± 1 %
= > 82 % capture efficiency
e+
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Required CLIC Pre-Damping Ring
PARAMETER PDR
energy [GeV] 2.424
circumference [m] 365.2
bunch population [10+9] 4.4
bunch spacing [ns] 0.5
number of bunches/train 312
number of trains 1
store time/train [ms] 20
rms bunch length [mm] at injection 5
rms momentum spread [%] at injection 2.7
hor. normalised emittance [m] at ejection 63
ver. normalised emittance [m] at ejection 1.5
hor./ver./ lon./ damping times [ms] 1 / 1 / 0.5
number of RF cycles 1
repetition rate [Hz] 50
RF frequency [GHz] 2
> ± 1%
as small as possible
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
CLIC base line configuration for e+ source
e-/TargetPrimary beam
Linac for e-
5 GeV
2 GHz
e
Target
AMD
Pre-injector Linac for e+
200 MeV
Thermionic gun
For the base line configuration, based on channeling process, a solution exists with a single target station providing unpolarized e+ to fulfill the CLIC parameters.
The channeling process allows a good e+ yield and one of the main advantage is the reduction of the beam energy deposition in the targets.
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
CLIC polarized e+ source
Undulator
Laser Compton Drive Beam Linac => no laser stacking cavity & no stacking
in the PDR
Storage Ring => laser stacking cavity + stacking in the PDR
ERL => laser stacking cavity + stacking in the PDR
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Undulator
K = 0.75
u = 1.5 cm
L = 100 m
Pre-Injector Linac
G = 20 MV/m
E = 200 MeV
fRF = 1.5 GHz
B = 0.5 T
Injector Linac
G = 17 MV/m
E = 2.424 GeV
f RF = 1.5 GHz
f rep= 50 Hz
CLIC 2007 based on undulator scheme
250 GeV
Cleaning chicane
NC Linac
2.2 GeV
To the IPe- beam
Ti alloy
450 m
e+ e+
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
•Drive e- beam energy: 250GeV•Undulator K: 0.75 •Undulator period: 1.5cm•Length of undulator: 100m•Drift to target: 450m•Accelerator gradient and focusing: 50MV/m for beam energy
<250MeV, 0.5T background solenoid field focusing; for 250MeV to 2.4GeV, 25MV/m with discrete FODO set.
•OMD: Non immersed, ramping distance 2cm• 1)7T-0.5T and 5T-0.5T, the thickness varies from 15cm to 80cm in
5cm steps;• 2) the thickness fixed at 20cm, B0-0.5T, B0 varies from 1 T to 10T
•Photon collimator: None•Target material: 0.4 rl Titanium, non-immersed•Yield is calculated as Ne+ captured/Ne- in drive beam.•Positron capture is calculated by numerical cut using damping ring
acceptance window: +/-7.5 degrees of RF(1.3GHz), x+y< 0.09m.rad,1% energy spread with beam energy ~2.4GeV
Optimizing for yield
W. Gai, W. Liu / ANL, J. Sheppard / SLAC
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Yield as function of drive beam energy & field
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Yield and polarization
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
e+ injector, 2.4 GeV
e- injector2.4 GeV
CLIC 3 TeV
e+ main linace- main linac , 12 GHz, 100 MV/m, 21.02 km
BC2BC2
BC1
e+ DR
365m
e- DR
365m
booster linac, 9 GeV
decelerator, 24 sectors of 876 m
IP
BDS2.75 km
BDS2.75 km
48.3 km
drive beam accelerator2.38 GeV, 1.0 GHz
combiner rings Circumferences delay loop 72.4 m
CR1 144.8 mCR2 434.3 m
CR1CR2
delayloop
326 klystrons33 MW, 139 s
1 km
CR2delayloop
drive beam accelerator2.38 GeV, 1.0 GHz
326 klystrons33 MW, 139 s
1 km
CR1
TAR=120m
TAR=120m
245m 245m
e+ PDR365m
e- PDR365m
Linac with optical cavities
e- beam sent to
+ 240 ns
CLIC 20008 based on Linac scheme
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Linac scheme with Drive Beam
Parameters CLIC
Energy 2.38 GeV
Current 101 A
Nb bunches / train 2904
e- Bunch population 5 x 1010
Bunch charge 8.4 nC
Repetition fequency 50 Hz
2.4 GeV 100A e- beam beam e+
beam
to e+ conv. target
V. Yakimenko and I. Pogorelski (BNL) proposal for ILC to be investigated for CLIC
12 GHz
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
The CLIC Injector complex (Compton)
3 TeV
Laser Compton ring configuration
Laser
Laser
DC gunPolarized e-
Pre-injector Linac for e-
200 MeVe+ Target
Pre-injector Linac for e+
200 MeV
Inje
ctor
Lin
ac
2.2
GeV
e+ DR2.424 GeV365 m
Boo
ster
Lin
ac
6.6
GeV 4 GHz
e+ BC1 e- BC1
e+ BC2 e- BC2e+ Main Linac e- Main Linac
2 GHz
e- DR
e- PDR
2 GHz 2 GHz
2 GHz 4 GHz
12 GHz 12 GHz
9 GeV48 km
e- Drive Linac 1.3 GeV
Compton ring
e+ PDR and Accumulator
ring
2 GHz
RF
gun
Stacking cavity
2.424 GeV365 m 2.424 GeV
365 m
2.424 GeV365 m
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
e+ t
arge
t
Pre-injector Linac for e+ 200 MeV
Inje
ctor
Lin
ac
2.2
GeV
e+ DR
2.424 GeV
2 GHz
2.424 GeV
Drive Linac 1.3 GeV
Compton ring
e+ PDR and Accumulator
ring
2 GHz50 Hz
CLIC Compton scheme
Compton configuration for polarized e+ and
low e+/yield
RF
gun
1 YAG Laser pulse
2 G
Hz
Stacking cavity
450 turns makes 312 bunches with 4.4x109 e+/bunch
C = 47 m, 156 ns/turn, 312 bunches with 6.2x1010 e-/bunch
9.8x106 pol. e+/turn/bunch
(23-29 MeV) 7x108 /turn/bunch
156 ns x450 turns => 70 s pulse length for both linacs
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
PARAMETER PDR
energy [GeV] 2.424
number of trains 1
rms momentum spread [%] at injection 2.7
hor./ver./ lon./ damping times [ms] 1 / 1 / 0.5
repetition rate [ms] 20
RF frequency [GHz] 2
CLIC Pre-Damping Ring optimization
1) The rms momentum spread at injection could be reduced by implementing: a) a bunch compressor at the entrance of the injector Linac b) a harmonic cavity which smooth the longitudinal distribution.
2) The transverse damping time should be ≈ 1 ms (in order to allow ≈ 10 damping times). It remains roughly 10 ms for the stacking.
3) The stacking efficiency could also be improved by putting 2 trains in the PDR.
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Compton e+ source parameters
Parameters CLIC 2007 CLIC 2008 ILC
Energy 1.3 GeV 1.06 GeV 1.3 GeV
Circumference 68 m 47 m 277 m
RF frequency 1.5 GHz 2 GHz 650 MHz
Bunch spacing 0.20 m 0.15 m 0.923 m
Nb bunches stored 311 312 280
e- Bunch population 6.2 x 1010 6.2 x 1010 6.2 x 1010
Nb optical cavities 1 1 30
Photons/bunch/turn 0.7 x 109 2.1 x 109 5.8 x 1010
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
CLIC Compton ring
E. Bulyak, P. Gladkikh / NCS KIPT
Parameters CLIC 2007 CLIC 2008
Energy 1.3 GeV 1.06 GeV
RF frequency 1.5 GHz 2 GHz
RF voltage 50 MV 150 MV
e- Bunch charge 10 nC 10 nC
e- bunch length at IP 5 mm 5 mm
Synchrotron losses 400 keV/turn 213 keV/turn
Laser photon energy 1.164 eV 1.164 eV
Laser rms pulse length 0.9 mm 0.9 mm
Laser rms pulse radius 0.005 mm 0.005 mm
Laser pulse energy 600 mJ 592 mJ
Full cycle (turns) 15000 15000
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
e+ t
arge
t
Pre-injector Linac for e+ 200 MeV
2 GHz
Drive Linac 1.06 GeV
Compton ring
2 GHz50 Hz
CLIC Compton scheme
Compton configuration for polarized e+ and high e+/yield
RF
gun
1 YAG Laser pulse
Stacking cavity
C = 47 m, 156 ns/turn, 312 bunches with 6.2x1010 e-/bunch
5 x108 pol. e+/turn/bunch
(10 - 20 MeV) 2.1x109 /turn/bunch
592 mJ
W sliced rod target 3 rad length => yield 0.48 e+ /
=> Stacking simplified
E. Bulyak / NCS KIPT
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Energy spread in CLIC Compton ring
E = 1.06 GeV
Double chicane
2 RF cavities => 150 MV
Emittances after 15000 turns:
H = 21 nm . rad
V = 1 nm . rad
Max energy spread ~ 1 %
E. Bulyak, P. Gladkikh / NCS KIPT
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Photons from CLIC Compton ring
E. Bulyak, P. Gladkikh / NCS KIPT
K: 0.5 mradI: 0.4 mradG: 0.3 mradE: 0.2 mradC: 0.1 mrad
Collimation anglesMax polarization ~ 75 %
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Studies and R&D for Compton scheme
Compton ring beam dynamics and design studies (NCS-KIPT, LAL, KEK, …)
Laser source (see Posipol 2006, 2007 and 2008 for companies involved )
Laser stacking cavity (KEK, LAL, IHEP, Hiroshima,… )
Target and e+ capture (LAL, IPNL-Lyon, ANL, CERN, IHEP,… )
e+ stacking in Pre-Damping Ring and Damping Ring (CERN,… )
Collaboration on CLIC study for e+ sources is always welcome
C L I CC L I C
16th June 2008POSIPOL 2008 L. Rinolfi / CERN
Conclusion
1) After the CLIC major changes in 2007, studies and optimization continue on the CLIC structures and possible changes could still occur.
2) For the unpolarized e+, a conventional source, based on channeling process, fulfills the CLIC requirements with a single target station.
3) For polarized e+ based on Undulator, studies continue.
4) For polarized e+ based on Compton back scattering, progress have been made (Ring & Linac) but several studies and R&D are still necessary.
5) The design of a CLIC e+ Pre-Damping Ring has just started.
The Compton ring seems the most promising option for CLIC polarized e+.
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