1. Prospettive ed Esperimenti Futuri a LIFE (il punto di vista della fisica dei fasci)
Luca Serafini, INFN-Milano
FE = Fasci Estremi
(Laboratorio Interdisciplinare con Fasci Estremi?)
Estremi in Phase Space Density (Brightness, Brilliance)
Estremi in Rapidity (peak flux, Np/Dt2 )
Estremi in Coherence and Duration (fs to attos X-ray pulses)
Estremi in Complexity and Multiplicity: synchronous (e-,X,hv), (p,X), (g,e+) (n,g,X,hv)
Estremi in Coupling e-/rad. (FEL, IFEL, AOFEL,Channeling)
I Workshop LIFE, LNF,

2. Brightness and Brilliance
Figures of Merit
Brightness and Brilliance
I Workshop LIFE, LNF,

3. The Brightness Chart [A/(m.rad)2]
AOFEL
n [m]
1013
1014
1015
1016
1017
I [kA]
1018
Self-Inj1
SPARX
Photo-injectors
SPARC
Ext-Inj2
SPARX 1 pC
The Brightness Chart [A/(m.rad)2]
1- see C. Benedetti’s talk
2 – see P. Tomassini’s talk
I Workshop LIFE, LNF,

4. The 6D Brilliance Chart [A/((m.rad)20.1%)]
Dg/g [0.1%]
1014
1015
1016
1017 Bn
AOFEL
SPARX 1 pC
SPARX
Self-Inj
Ext-Inj
SPARC
The 6D Brilliance Chart [A/((m.rad)20.1%)]
I Workshop LIFE, LNF,

5. Rapidity
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6. Physical Principles of the Plasma Wakefield Accelerator
Courtesy of T. Katsouleas
Plasma acceleration experiments with SPARC/X e- beams
Space charge of drive beam displaces plasma electrons - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + + + - - - + - - - - - + + - - + + + + + - - - + + + + + + + - + + + + - - - + + + - + + + + + + + + + - - + + + + + + + + + + + - - - - - - - - - - - -
electron beam - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Ez
Plasma ions exert restoring force => Space charge oscillations
Wake Phase Velocity = Beam Velocity (like wake on a boat)
Wake amplitude
Transformer ratio
I Workshop LIFE, LNF,

7. I Workshop LIFE, LNF,

8. Scattered photons in collision
Thomson
X-section
Scattered flux
Luminosity as in HEP collisions
Many photons, electrons
Focus tightly
Short laser pulse; <few psec (depth of focus)
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9. Rapidity
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10. Coherence and Time Duration
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11. AOFEL CO2 envelope CO2 focus TiSa envelope e- beam plasmar
m]
TiSa envelope
TiSa pulse
e- beam
plasma
Lsat=10LG=1.3 mm (=0.002)
Z [m]
I Workshop LIFE, LNF,

12. Longitudinal phase space and density profile
Selection of best part
in the bunch:
40 pC in 2 fs (600 nm)
projected rms
n = 0.7 m
<>
<>

I Workshop LIFE, LNF,

13. GENESIS Simulations starting from actual phase space
from VORPAL (with oversampling)
=2.5 m (CO2 laser focus closer to plasma)
Simulation with real bunch
After 1 mm : 0.2 GW in 200 attoseconds Lbeff < 2 Lc
I Workshop LIFE, LNF,

14. GENESIS Simulations for laser undulator at 1 m
to radiate at 1 Angstrom
Peak power 100 MW
in 100 attoseconds
Average power (Lsat~500 m, Psat~10 MW)
Coherence
Time duration
Simulation with real bunch =3.5 m
Field
I Workshop LIFE, LNF,

15. I Workshop LIFE, LNF,

16. Slice 8, I=25 kA
Equivalent Cathode
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17. Multeplicity and Complexity
I Workshop LIFE, LNF,

18. Two ways to get pol. e+ (1) Helical Undurator (2) Laser Compton
courtesy of T. Omori (KEK)
e- beam
E >150 GeV
Undulator
L > 200 m
Our Proposal
(2) Laser Compton
I Workshop LIFE, LNF,

19. I Workshop LIFE, LNF,

20. An electron beam energy up to 1
An electron beam energy up to 1.5 Gev would allow the production of polarized photons at 50 MeV, which seems the optimized photon energy for efficient production of polarized photons
I Workshop LIFE, LNF,

21. Preliminary calculations show that up to 1010 polarized photons per pulse should be expected using about 1.0 J of infrared radiation and a 1 nC beam focused to spotsizes of 5 microns. Including the capture efficiency, we can estimate up to few per cent (2 %) of these photons to yield a usable polarized positron.
I Workshop LIFE, LNF,

22. With a smaller electron energy (< 300 MeV), like in the case of the upgraded SPARC energy, the energy of ICS photons is smaller (about 2-4 MeV photons ), still useful for e+ polarization tests.
I Workshop LIFE, LNF,

23. Gamma on D2O Photo-neutron Source
Gamma from the “LIFE” Thomson backscattering source
Target of heavy water D2O (cost about 400€/l)
Target dimension (used in simulations) F=2cm - 1 mm ; length 10, 25, 50 cm (target filling cost :12-60 € for F=2cm)
Take advantage of high peak flux of monochromatic g beams from tunable, mm spot size, ps pulse Thomson Source
I Workshop LIFE, LNF,

24. Neutron Produced: F. Broggi, FLUKA2
Photon beam
Photon beam diameter = 1 mm FWHM
Photon fluence
Simulation performed with 10 different runs of 106 primary photons
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25. Neutron produced vs photon energy/target length (Target diameter 2 cm)
Optimum g energy about 5 MeV
The forward production decreases with the target length (self-absorption):
The backward production is constant
The side production increases with the target length.
I Workshop LIFE, LNF,

26. Neutron Spectra (5 MeV gamma on 25 cm D2O) (target diameter 2 cm)
The maximum n energy is about
by arranging the photon energy different neutron energy will be available.
I Workshop LIFE, LNF,

27. Target diameter 1 mm
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28. Small-Big Target Small Target Large Target Neutron/g Error % Forward
Side
2.69E-03
8.53E-02
2.65E-03
2.89E-03
Back
2.82E-06
2.63E+00
6.76E-05
3.90E+00
I Workshop LIFE, LNF,

29. Coupling
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30. IFEL acceleration (P. Musumeci)
Inverse Free Electron Laser accelerator is a proven and reliable technique to accelerate with very high gradient high quality electron beams. (successful UCLA and BNL)
It is not well suited for HEP applications, but renovated interested in the US as light sources driver application (UCLA-LLNL funded proposal).
Two steps:
An undulator to demonstrate 200 MeV/m energy gradient is already UCLA. Need 3-4 TW 100 fs laser beam.
For 1.7 GeV module need 20 TW 100 fs laser beam + helical undulator.
I Workshop LIFE, LNF,

31. IFEL acceleration@SPARC
Sending the IFEL beam into an undulator
FEL l = 3 nm (water window)
Slippage dominated regime.
Start-to-end --TREDI into GENESIS-- simulations (see Musumeci, FEL talk Berlin 2006)
With full FLAME power, final energy after 2 m optimized helical undulator could increased to > 2.1 GeV.
Simulated longitudinal phase space output
I Workshop LIFE, LNF,

32. @ Channeling of Charged Particles
@ Amorphous:
@ Channeling:
Atomic crystal plane
planar channeling e + e-
Atomic crystal row (axis)
axial channeling e-
the Lindhard angle is the critical angle
for the channeling

33. Channeling of Charged Particles &
Channeling Radiation
@ Channeling:
Atomic plane of crystal e +
- the Lindhard angle is the critical angle for the channeling
@ Channeling Radiation:
CUP project studies the positron channeling for the development of Crystal Undulator for Positrons and represents the first step of an ambitious project that investigates the possibility to create new, powerful sources of high-frequency monochromatic electromagnetic radiation: crystalline undulator and -laser, based on crystalline undulator. The physical phenomena to investigate are essentially two: the spontaneous undulator radiation by channeling of relativistic positrons and the stimulated emission in periodically bent crystals (the lasing effect).
- optical frequency
Doppler effect -
Powerful radiation source of X-rays and -rays:
polarized
Tunable (keV - MeV)
narrow forwarded

34. Channeling Radiation - @ Channeling Radiation: - optical frequency
Doppler effect -
Powerful radiation source of X-rays and -rays:
polarized
tunable
narrow forwarded

35. Channeling Radiation & Thomson Scattering
- radiation frequency -
- number of photons per unit of time -
- radiation power -
@ comparison factor:
Laser beam size & mutual orientation
@ strength parameters – crystal & field:

36. Channeling Radiation &
Thomson Scattering
For X-ray frequencies: 100 MeV electrons channeled in 105 mm Si (110) emit ~ 10-3 ph/e-
corresponding to a Photon Flux ~ 108 ph/sec
ChR – effective source of photons in very wide frequency range:
in x-ray range – higher than B, CB, and TS
however, TS provides a higher degree of monochromatization and TS is not undergone incoherent background, which always takes place at ChR

37. Conclusions
Self-Inj : neutron source, aferburner (relativistic piston)
Ext-Inj: polarized positrons (test, compact GeV, good brightness)
AOFEL: table top X-FEL (max brightness, step density gas jet)
10 MeV’s g beams: nuclear physics (Giant Resonances)
Photoinjector beams still playing relevant role in years to come (FEL, IFEL, Channeling, THz, TS, etc.)
I Workshop LIFE, LNF,

38. I Workshop LIFE, LNF,

39. @ Channeling: Continuum model
screening function of Thomas-Fermi type
screening length
Molier’s potential
Lindhard potential
…… Firsov, Doyle-Turner, etc.
Lindhard:
Continuum model –
continuum atomic plane/axis potential

40. @ Bremsstrahlung & Coherent Bremsstrahlung vs Channeling Radiation
@ amorphous - electron:
Radiation as sum of independent impacts with atoms
Effective radius of interaction – aTF
Coherent radiation length lcoh>>aTF
Deviations in trajectory less than effective radiation angles:
Nph
Quantum energy

41. @ Bremsstrahlung & Coherent Bremsstrahlung vs Channeling Radiation
@ interference of consequent radiation events:
phase of radiation wave
Radiation field as interference of radiated waves:
Coherent radiation length can be rather large even for short wavelength
@ crystal: d
Nph
Quantum energy

42. @ Bremsstrahlung & Coherent Bremsstrahlung vs Channeling Radiation
@ crystal: d
channeling
at definite conditions channeling radiation can be significantly powerful
than bremsstrahlung B:
CB:
ChR: