Compton Collision Scheme of E-Gammas Proposal for ELI-NP
Luca Serafini – INFN Milan
• ELI-NP: third Pillar of Extreme Light Infrastructure (large European
Initiative on Extreme Light, 900 M€), devoted to Nuclear Photonics
• One of the two Main Components of ELI-NP: advanced Gamma Source -
Bright, Mono-chromatic (0.3%), High Spectral Flux (> 104 ph/sec.eV),
Tunable (1-20 MeV), Highly Polarized
• Tender is open for Best Proposal (60 M€): Egammas European
Collaboration is preparing to submit
• Innovative solution for Compton -ray Source based on advanced C-band
RF Linacs in multi-bunch mode and New Concepts for Laser Recirculation:
maximizing Luminosity of Compton Source
SAPPHiRE Day, CERN, Feb 19th 2013
Extreme Light Infrastructure (ELI)
Gerard Mourou 1985: Chirped Pulse Amplification (CPA)
ELI
Courtesy of Victor Zamfir
Extreme Light Infrastructure
ELI on ESFRI list
ELI-PP 2007-2010
December 2009 (EC)
3 Pillars
(Structural Funds):
CZECH Rep: Beamlines
HUNGARY: Short Pulses
ROMANIA: Nuclear Physics
Courtesy of Victor Zamfir
ELI-Nuclear Physics
“White Book” (100 scientists, 30 institutions, eds. Habs et al.)
(www.eli-np.ro) Feasibility Study: 293 Meuro w/o VAT
“Extreme Light” :• two 10 PW APOLLON-type lasers• brilliant γ beam, up to 20 MeV, BW:10-3 produced by Compton scattering on a 700 MeV electron beam
ELI-NP γ beam
SAPPHiRE Day, CERN, Feb 19th 2013
The Tender for ELI-NP Gamma Systemwas published in early Dec. 2012: deadline March 10th 2013
• The Challenge we are facing: design the most advanced Gamma Beam
System based on state-of-the-art components, to be commissioned and
delivered to users by mid 2017, reliable, cost-effective (60 M€ Total Cost),
compatible with present lay-out of ELI-NP building
• Prototype of a New Generation (Light) Gamma-ray Sources: Bright, Mono-
chromatic (0.3%), High Spectral Flux (> 104 ph/sec.eV), Tunable (1-20
MeV), Highly Polarized, based on Compton Back-Scattering of High Phase
Space Density Electron Beams by Lasers
The EGAMMAS European Collaborationhas been preparing its Proposal since Sept. 2011
Plus 6 Industrial Partners and Sub-Contractors:[Amplitude, Thales, Alsyom] (F), Comeb (I), RI (D), Danfysik (Dk)
SAPPHiRE Day, CERN, Feb 19th 2013
• Because of Budget/Space-available/Implementation-schedule Constraints we
were obliged to discard Super-Conducting Technology for the Linac.
• The Baseline is therefore based on a room temperature low rep rate (100
Hz) 700 MeV Linac, delivering maximum phase space density of bunches
generated in trains, coupled to a High Average Power (100 Hz, 100 W) psec
J-class Laser system, recirculated at each collision to collide with all the
electron bunches in the train.
SAPPHiRE Day, CERN, Feb 19th 2013
We built a set of criteria for optimal design of theGamma Beam System,
based on the concept of Spectral Luminosity,i.e. Luminosity per unit bandwidth
electrons laser
• Scattered flux• Luminosity as in HEP
collisions– Many photons, electrons– Focus tightly
– ELI-NP
• Scattered flux• Luminosity as in HEP
collisions– Many photons, electrons– Focus tightly
– ELI-NP
σ T =8π
3re
2N =LσT
L =NLNe−
4πσ x2
€
σT = 0.67 ⋅10−24 cm2 = 0.67 barn
f
€
L =1.3⋅1018⋅1.6⋅109
4π 0.0015cm( )2 3200(sec−1) =
2.5⋅1035cm−2sec −1
€
Gamma − ray Energy : 1− 20 MeV
€
rms Bandwidth : 0.3%
€
Spectral Density : 104 photons /sec⋅ eV
Gamma Beam System Characteristics
1-2 Orders of magnitude better than state of the art
HiGS (bdw 3%, sp. dens. 102, E < 8 MeV)
€
rms divergence < 200 μrad
(spot size < 5 mm at target)
SAPPHiRE Day, CERN, Feb 19th 2013
102 103 104 105 106
10-17
1x10-16
10-15
1x10-14
1x10-13
1x10-12
1x10-11
02
0L mc
h
4
1
Back-scattering
Radiation on-axis
Thomson factor
Comptonred shift
102 103 104 105 10610-4
10-3
10-2
10-1
100
- D
/( D
)
ELI=10-2
Negligiblerecoil
Dominantquantum effects
T
T
λλ
λλ
1/0
2
1/0
€
ν =ν4γ 2
1+ γ 2θ 2 + a02 2
1 − Δ( )
Δ =4γ hν mc 2
1+ 2γ hν mc 2 ; Δ <<1 Compton recoil
a0 <<1 and γθ <<1 for small bandwidths
Compton Recoil
= electron relativistic factor= angle of observation ( = 0 -> photon scattered on electron beam propagation axis)ν = laser frequencyν = frequency of the scatterd (X,) photon
€
a0 = 4.3λ
w0
U J[ ]σ t ps[ ]
a0 = dimensionless amplitude of the vector potential
for the laser e.m. field , a0=eE0/(Lmc)
€
Nγ = 2.1⋅108 UL J[ ]Q pC[ ] fRF nRF
hν eV[ ]σ x2 μm[ ] 1+ cσ tφ /4σ x( )
2
scattered − photons /sec over 4π and total spectrum
Total Scattered Photons
fRF = RF rep rate
nRF = #bunches per RF pulse
UL = Laser pulse energy
Q = electron bunch charge
hν = laser photon energy [eV]
σx = electron bunch spot size at collision point
= collision angle (<<1)
= 0 for head-on collision
σt = laser pulse length all sigma’s and angles are intended as rms, all distributions are assumed as gaussians in (phase) space and time
SAPPHiRE Day, CERN, Feb 19th 2013
The Luminosity based description of Compton Back-scatteringallowed us to develop a simple powerful analytical model
predicting with great accuracy the number of photonsgenerated within the desired bandwidth (Spectral Luminosity)
and all related quantities like Spectral Density,photon beam emittance, Brilliance, etc
CAIN results€
Nγbw =1.2⋅109 UL J[ ]Q pC[ ] fRF nRF
hν eV[ ]σ x2 μm[ ]
Ψ2
scattered − ph /sec within Ψ ≡ γϑ
€
ν
ν
≅ (γϑ )4 + 4Δγ
γ
⎛
⎝ ⎜
⎞
⎠ ⎟
2
+ε n
σ x
⎛
⎝ ⎜
⎞
⎠ ⎟
4
+Δν
ν
⎛
⎝ ⎜
⎞
⎠ ⎟2
+M 2λ L
2πw0
⎛
⎝ ⎜
⎞
⎠ ⎟
4
+a0 p
2 /3
1+ a0p2 /2
⎛
⎝ ⎜ ⎜
⎞
⎠ ⎟ ⎟
2€
ν =ν4γ 2
1+ γ 2θ 2 + a02 2
1− Δ( ) ; if a0 = a0pe−t 2 2σ t
2
⇒ νγ =4γ 2ν 1− Δ( )
1+ γ 2θ 2 +1
3
a0 p2
2
RMS bandwidth, due to collection angle, laser phase space distribution
and electron beam phase space distribution
€
Optimized Bandwidth ≅ (ε n /σ x )2
€
2ϑ 2 ≅ (σ px /mc) ≅ (ε n /σ x )
€
Maximum Spectral Density ∝ Luminosity /(ε n /σ x )2 ∝ Q /ε n2
€
Maximum Spectral Density ∝ Phase Space density ηn
€
Ψ=ϑ normalized
rms collection angleelectron beam laser
CAIN (quantum MonteCarlo)Run by I.Chaichovskaand A. Variola
TSST (classical)Developed byP. Tomassini
Comp_Cross (quantum semianalytical)Developed by V.Petrillo
COMPARISON between classical (TSST), quantumsemianalytical (Comp_cross) and quantum MonteCarlo (CAIN)
Number ofphotons
bandwidth
V. Petrillo et al., NIM-A693 (2012) 109
4,80 4,90 5,000
1
2
3
4
5
(c)(b)
dN/d
E (e
V-1
)
E(MeV)
(a)
(a)CAIN(b)Comp_Cross(c)TSST
Quantum shift E
A part from the quantum shift, the spectra are very similar
SAPPHiRE Day, CERN, Feb 19th 2013
Outstanding electron beam quality:ultra-high phase space densityin single bunch beam dynamics
First multi-bunch start-to-end with HOM damped C-band cavitiesNo significant emittance dilution observed from beam break-up
SAPPHiRE Day, CERN, Feb 19th 2013
General procedure we would like to follow: input/output couplers are fabricated separately and joined to the cells by a vacuum flange
The fabrication of a prototype with a reduced number of cells is necessary to:A.Test the effectiveness of the dipole mode damping including the test the absorbing material performancesB.Test the vacuum properties of the structure with absorbing materialC.Perform the low power tests and the tuning of the structureD.Test the high gradient performances of the structure
ELI Damped structure: Mechanical drawings, realization and prototype
SAPPHiRE Day, CERN, Feb 19th 2013
WORKSHOP 2012WORKSHOP 2012European Proposal for ELI-NP Gamma Beam System:European Proposal for ELI-NP Gamma Beam System:
the Machine and the Experimentsthe Machine and the Experiments
Milan, ItalyMilan, ItalyMay 14-16May 14-16
Palazzo delle StellinePalazzo delle StellinePalazzo delle StellinePalazzo delle Stelline
ELI-NPELI-NPBucharest (Magurele)Bucharest (Magurele)
Romania for ELIRomania for ELI
ELI-NPELI-NPBucharest (Magurele)Bucharest (Magurele)
Romania for ELIRomania for ELI
ChairsAngela Bracco (Univ. Milano and INFNINFN)
Luca Serafini (INFN Milano)
ChairsAngela Bracco (Univ. Milano and INFNINFN)
Luca Serafini (INFN Milano)
www.e-gammas.eu
SAPPHiRE Day, CERN, Feb 19th 2013
SAPPHiRE Day, CERN, Feb 19th 2013
€
L ∝ Nγshot
( )2
f = 2.0⋅1021 N.B. in the Thomson limit
€
with σC = 0.5 μm L ∝ Nγshot
( )2
f = 2.0⋅1024 ⋅ (0.52) x =1
with σ IP = 0.1 μm L = 2.0⋅1033⋅ (0.52) x =1
SAPPHiRE Day, CERN, Feb 19th 2013
Thanks for your attention
Thanks to:
F. Zomer and K. Dupraz (Univ. Paris Sud and Orsay/LAL) &Alsyom for Laser Recirculator
V. Petrillo (Univ. of Milan and INFN/Milan) for gamma ray Spectra
C. Vaccarezza (INFN/LNF) for Beam Dynamics
D. Alesini (INFN/LNF) for C-band HOM Damped Acc. Structures
N. Bliss (STFC) for Lay-out
www.e-gammas.eu
SAPPHiRE Day, CERN, Feb 19th 2013
• Detailed description of the diagnostics instrumentation for
electron beam throughout the linac.
•
• Mature design for the collimation at low and
high energy beam lines.
• Advanced study for monitoring and characterizing the gamma
ray beam by means of
luminometers and calorimeters.
SAPPHiRE Day, CERN, Feb 19th 2013
€
SPD
€
σx μm[ ]
€
w0 μm[ ]
320 MeV
the floor levelis at 104
€
SPD
€
φ deg( )
520 MeV
360 MeV
720 MeV
Scan the Dynamic Range
SAPPHiRE Day, CERN, Feb 19th 2013
SAPPHiRE Day, CERN, Feb 19th 2013
Set the Parameter Table
SAPPHiRE Day, CERN, Feb 19th 2013
SAPPHiRE Day, CERN, Feb 19th 2013
SAPPHiRE Day, CERN, Feb 19th 2013