ILC e source and discussion

1
Disussion for ILC e-/e sources KURIKI Masao
(KEK)

• ILC e source and discussion
• ILC e- source and discussion

Powered by
2
ILC Source Requirement

• Undulator scheme has been selected as a baseline.
• Laser-Compton scheme is a future alternative.
• Conventional scheme is a backup option.

3
Conventional Scheme

• 6 GeV 3.2nC 2800 electron driver linac.??????????
• 4 X0 W-Re rotation target (360m/s/ of target)
• 3.2nC positron in 0.04 m.rad (0.09m.rad DR
  acceptance)

4
Two ways to get pol. e
(1) Helical Undurator
e- beam E gt150 GeV
Undulator L gt 150 m
(2) Laser Compton
5
New design
Re-cycling Concept
laser pulse stacking cavities
positron stacking in main DR
Compton ring Electron storage ring
to main linac
6
(No Transcript)
7
Linac Scheme by V. Yakimenko

• polarized ?-ray beam is generated in the Compton
  back scattering inside optical cavity of CO2
  laser beam and 4 GeV e-beam produced by linac.
• The required intensities of polarized positrons
  are obtained due to 10 times increase of the
  e-beam charge (compared to non polarized case)
  and 5 to 10 CO2 laser system IPs.
• Laser system relies on the commercially available
  lasers but need RD for the new mode of operation
• 5ps 10J_at_0.05 Hz CO2 laser is operated at ATF

8
Polarised positron source Compton cavities ERL
Positron damping ring
9
Laser Diode
Laser Diode
150 fs, 73 MHz
40/170
40/170
OI
Transmission grating compressor
Gold grating-based strectcher
75 efficiency
F. Röser et al. Optics letters, 30, p2754, 2005
10
RD items

• Compton ring simulation study
• Basic beam dynamics study
• hardware RD for bunch length modulation(optional
  / in future)
• Optical Cavity
• experimental RD
• e stacking in DR
• Basic beam dynamics study
• Laser Cooporation with various companies.
• CO2 laser
• Mode-lock laser
• Fiber laser

11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
ILC electron source and discussion
17
ILC electron source
18
ILC Basic Layout
standard ILC SCRF modules
room-temperature accelerating sect.
laser
Guns
diagnostics section
DC gun 120 keV HV
Laser requirements pulse energy gt 5 uJ pulse
length 2 ns pulses/train 2820 Intensity
jitter lt 5 (rms) pulse spacing 337 ns rep.
rate 5 Hz wavelength 750-850 nm
Photocathodes GaAs/GaAsP strained super-lattice
Room temperature linac Allows external focusing
by solenoids Same as e capture linac
19
By N. Yamamoto (Nagoya Univ.)
20
TiAl2O3 OPCPADESY Max Born
I. Will, H. Redlin, MBI Berlin
up to 900 us
21
TiAl2O3 Macro-pulse PumpSLAC

• TiAl2O3 mode lock PP for seed laser
• NdYAG driven laser amplification with TiAl2O3
  crystal.

22
YbYAG fiber laser NOPAKEK LAAA

• YbYAG mode lock PP Yb fiber laser amp.
  NOPA?
• High stability by LD pumping.
• Efficient amp.
  by Yb fiber laser.
• Wave length vari-
  ability by NOPA

23
Overall Schematic by ILC-GDE electron AG

• Dual injectors for redundancy.
• SC linac up to 5 GeV.
• Spin rotator and energy compressor.

24
ILC electron source RD items

• Cathode
• More QE with high Pol.
• Longer Operation time
• Robust material

25
ILC electron source RD items

• HV gun operation
• Low dark current.
• Bunching
• System optimization
• Everything linear makes everyone happy.

26
ILC electron source RD items

• Laser RD
• TiSapphire OPCPA is the baseline?
• TiSapphire NdYLF laser amp. is more
  promising?
• Recent rapid progress of fiber laser amplifier
  can be applicable?

27
ILC electron source RD items

• Alternative Idea
• NC Pol RF gun
• SC Pol RF gun

28
ILC electron source RD items

• System design
• Gun HV
• Bunch length at the cathode
• Buncher
• Collimator
• SC linac
• Spin rotator
• Do we need Energy Compressor?

29
Backup Slides
30
Posipol scheme we are working on a proposal for
a unique lepton source ERL based
1) We have a Post Doc !!!!!!
Conventional positron source
Positron damping ring
31
Two ways to get pol. e
(1) Helical Undurator
e- beam E gt150 GeV
Undulator L gt 150 m
(2) Laser Compton
32
Experiment at BNL ATF(record number of X-rays
with 10 ?m laser)

• More then 108 of x-rays were generated in the
  experiment PR ST 2000. NX/Ne- 0.1.
• (0.35 as of April 2006- limited by laser/electron
  beams diagnostics)
• Interaction point with high power laser focus of
  30?m was tested.
• Nonlinear limit (more then one laser photon
  scattered from electron) was verified. PRL 2005.

33

• beam structure CLIC has a
• smaller bunch charge (about 10x less) and
• less bunches per pulse (about 20x less)
• bunch spacing in DR 0.533 ns instead of 2.8 ns
• ? layout of optical cavities more challenging
• ? multiple pulses stored in one cavity?
• damping ring CLIC damping ring needs beam with
• extremely small emittance, limited dynamic
  aperture
• ?pre-damping ring is required
• Optimize pre-damping ring for stacking polarized
  
• e from Compton source
• CLIC repetition rate is 150 Hz instead of 5 Hz
  for ILC

34
Why Laser Compton ?

• Positron Polarization.
• Independence
• Undulator base e source has inter-system
  dependency.
• Laser base e source is independent.
• Easier construction, operation, commissioning,
  maintenance.
• Low energy operation
• Undulator-base e need deceleration.
• Laser-base e has no problem.

35
Schematic View of Whole System