compton collision scheme of e-gammas proposal for eli-np luca serafini – infn milan eli-np: third...

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


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)


• 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.


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)


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


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


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


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

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


€

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


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

• 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.


€

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



Set the Parameter Table

compton collision scheme of e-gammas proposal for eli-np luca serafini – infn milan eli-np: third...

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