Advanced Compton Sources (for Nuclear Photonics) Luca Serafini – INFN/Milan Physics and Technology of Compton/Thomson X/  rays Sources - weak Compton recoil regime (typical of machines for Nuclear Photonics) Some new studies on the dynamics of electrons emerging after the collision with laser pulses in Compton/Thomson Sources Main Challenges of ELI-NP advanced Gamma Source - Bright, Mono- chromatic (0.3%), High Spectral Flux (> 10 4 ph/sec. eV), Tunable (1-20 MeV), Highly Polarized 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 EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

1-25 GeV electrons Å photons cm und. period  u FEL’s and Thomson Sources common mechanism: collision between a relativistic electron and a (pseudo)electromagnetic wave MeV electrons 0.8  m laser  keV photons 3 km 20 m

FEL resonance condition (magnetostatic undulator ) Example : for R =1A, w =2cm, E=7 GeV (electromagnetic undulator ) Example : for R =1A, =0.8  m, E=25MeV laser power laser spot size EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

Angular and Frequency Spectrum (560 MeV electrons) EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

Back-scattering Radiation on-axis Thomson factor Compton red shift ELI  =10 -2 Negligible recoil Dominant quantum effects 1/  0 2 1/  0 EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

Compton Recoil  = electron relativistic factor  = angle of observation (  = 0 -> photon scattered on electron beam propagation axis) = laser frequency  = frequency of the scatterd (X,  ) photon a 0 = dimensionless amplitude of the vector potential for the laser e.m. field, a 0 =eE 0 /(  L mc) EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

Thomson/Compton Sources are electron-photon Colliders, based on the concept of Spectral Luminosity, i.e. Luminosity per unit bandwidth negligible diffraction 0 crossing angle 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 f cfr LHC SuperB-fac 10 36

Advanced Gamma Beam Requirements 1-2 Orders of magnitude better than state of the art HiGS (bdw 3%, sp. dens. 10 2, E < 8 MeV) EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

Total Scattered Photons f RF = RF rep rate n RF = #bunches per RF pulse U L = Laser pulse energy Q = electron bunch charge h  = laser photon energy [eV]  x = electron bunch spot size at collision point  = collision angle (<<1)  = 0 for head-on collision  t = laser pulse length  all sigma’s and angles are intended as rms, all distributions are assumed as gaussians in (phase) space and time EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

h  eV h  eV  eV) ELI-NP U= 1 Joule  t = 4 psec Q=250 pC ( e - ) h = 2.4 eV  = total # scatt. photons over solid angle per shot  x  m) All quantities below are per shot (i.e. n RF =1 f RF =1) EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

The Luminosity based description of Compton Back-scattering allowed us to develop a simple powerful analytical model predicting with great accuracy the number of photons generated within the desired bandwidth (Spectral Luminosity) and all related quantities like Spectral Density, photon beam emittance, Brilliance, etc CAIN results

Energy-angular Spectral distribution EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

ELI-NP Beam-B  T = 360 MeV  =  n = 0.46  m  x = 20  m EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

# scattered photons / shot. eV EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

RMS bandwidth, due to collection angle, laser phase space distribution and electron beam phase space distribution electron beam laser forbids ultra focused beams

e-e- X e-e- X focus envelope Spectral broadening due to ultra-focused beams: Thomson Source classically described as a Laser Syncrotron Light Source Scattering angle in Thomson limit (no recoil) is small, i.e. < 1/  EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

X Spectral broadening due to ultra-focused beams: Thomson Source classically described as a Laser Syncrotron Light Source focus Limit to focusability due to max acceptable bandwidth EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

S-120 C-170 X-200 C-200 C-240 S-120 LCLS (exp) L-60 TESLA (exp) LLNL-MegaRay (sim) ELI-NP  -source Eur. Prop. (sim) Transverse Phase Space Density (round beams) : the chart of RF Photo-Injectors Q [pC] psec bunches RF EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

320 MeV the floor level is at MeV 720 MeV Scan the Dynamic Range with 32x100 Hz EAAC-2013, LaBiodola (Elba), Italy, june 3rd MeV

Scaling Laws: final set EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

(a)CAIN (b)Comp_Cross (c)TSST Quantum  shift  E A part from the quantum shift, the spectra are very similar EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

CAIN (quantum MonteCarlo) Run by I.Chaichovska and A. Variola TSST (classical) Developed by P. Tomassini Comp_Cross (quantum semianalytical) Developed by V.Petrillo COMPARISON between classical (TSST), quantum semianalytical (Comp_cross) and quantum MonteCarlo (CAIN) Number of photons bandwidth V. Petrillo et al., NIM-A693 (2012) 109 EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013

Seminar at KEK - Tsukuba – April 17th 2013

EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013 Accelerator and Equipments in ELI-NP Building ELI-NP-GS

EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013 in single bunch mode We need multi-bunch operation !

EAAC-2013, LaBiodola (Elba), Italy, june 3rd 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 performances B.Test the vacuum properties of the structure with absorbing material C.Perform the low power tests and the tuning of the structure D.Test the high gradient performances of the structure ELI Damped structure: Mechanical drawings, realization and prototype courtesy of D.Alesini

First multi-bunch start-to-end with HOM damped C-band cavities No significant emittance dilution observed from beam break-up courtesy of C.Vaccarezza

EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013 courtesy of F. Zomer

EAAC-2013, LaBiodola (Elba), Italy, june 3rd 2013 Main Parameter Tables of ELI-NP-GBS

EAAC-2013, LaBiodola (Elba), Italy, june 3rd 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 X/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 of EI-NP-GS