1 WP Compton Sources C. Vaccarezza

2 Outline The WP: Scientific case The ELI-NP expertizeA. Bacci, I. Drebot, A. Giribono, V. Petrillo, L. Serafini, C. Vaccarezza Scientific case The ELI-NP expertize 1 GeV Compton source first results

3 Gamma-ray Compton SourcesThanks to the extremely advanced characteristics: energy, tunability, mono-chromaticity, collimation, brilliance, time rapidity, polarizability etc. the new generation of Compton Sources will play a critical role for advanced applications in many fields: Nuclear resonance fluorescence, Nuclear photonics with (γ-p) (γ-n) reactions, New medical isotopes production, Material studies, Radioactive waste management and isotope identification, High brilliance Neutron sources ecc. ecc. ELI-NP, the Nuclear Physics Pillar of ELI is building an advanced Compton Source (Gamma Beam System) aiming at making a substantial step forward in g-ray beam performances

4 In detail: With a 2.3 eV laser beam and:MeV Linac MeV 𝜸 beam: GDR (Giant Dipole Resonance) 1.1 GeV Linac MeV 𝜸 beam: 2nd harm. GDR effects (never observed up to now) 1.35 GeV Linac 60 MeV 𝜸 beam: Polarized Positron Source by ICS polarized photons (P. Musumeci& L. Serafini provate comm., Omori NIM A 500,232, 2003)

5 ELI-NP GBS European Collaboration: From building delivery:Italy: INFN,Un. Sapienza France: IN2P3, Un. Paris Sud UK: ASTeC/STFC From building delivery: 3.5 MeV 𝜸 beam : 1.5 years 19.5 MeV 𝜸 beam: 3-4 years

6 EuroGammaS Organisational Breakdown Structure (OBS) Hierarchical management structure, communication routes and reporting links Governing Board Institute Partner Members Industrial Partner Members Project Coordinator, Machine Leader, Q&C Manager IFIN-HH Project Coordinator Luigi Palumbo Project Office Technical TEAM Finance Manager (Sabrina Argentati) Q&C Manager (Antonio Napolitano) Machine Leader (Alessandro Variola) INFN Scientific Coordinator (Luca Serafini) Legal Advisors (Nicolas Castoldi, Fabio MIccoli) Deputy (Optics) (Fabian Zomer) CNRS Deputy (Linac) (David Alesini) INFN Training Manager (tba) Safety Coordinator (Sandro Vescovi) Deputy (Integration) (Antonio Falone) INFN Work Packages WP 01a Accelerator Physics (Cristina Vaccarezza) INFN Frascati WP 01b Source Physics (Vittoria Petrillo) INFN Milan WP 02 Optics (Kevin Cassou) CNRS WP 03 Accelerating Structures (David Alesini) INFN Frascati WP 04a High Power RF & Distribution (Roberto Boni) INFN Frascati WP 04b LLRF & syncrhonisation (Alessandro Gallo) INFN Frascati WP 05 STFC Modules, Magnets & Vacuum (Neil Bliss) STFC Daresbury WP 06 INFN Modules (Sandro Tomassini) INFN Frascati WP 07 Diagnostics (Andrea Mostacci) INFN Frascati WP 02A Lasers (Franck Falcoz) Amplitude WP 02B Interaction chambers (Herve Rocipon) Alsyom WP 08 Control System (Giampiero Di Pirro) INFN Frascati WP 09 Gamma Systems (M. Gambaccini) INFN Ferrara WP 10 Radioprotection (Adolfo Esposito) INFN Frascati WP 11a CAD/3D integration layout (V. Pettinacci) INFN WP 11c Electrical Power (Ruggero Ricci) INFN WP 11d Cooling & Air (Ugo Rotundo) INFN

7 ELI-NP Source SpecificationsNew generation γ-source: High Phase Space density electron beams vs Lasers Energy [MeV] 0.2 – 19.5 Spectral Density [ph/s∙eV] 0.8 – 4∙104 Bandwidth rms [%] ≤ 0.5 # photons/pulse within FWHM bdw. ≤ 2.6∙105 # photons/s within FWHM bdw. ≤ 8.3∙108 Source rms size [mm] 10 – 30 Source rms divergence [mrad] 25 – 200 Peak brilliance [Nph/s∙mm2∙mrad2∙0.1%] 1020 – 1023 Radiation pulse length rms [ps] 0.7 – 1.5 Linear polarization [%] > 99 Macro repetition rate [Hz] 100 # pulses per macropulse 32 Pulse–to–pulse separation [ns] 16 Polarization axis wiggling [deg] < 1 Synchronization to an external clock [ps] Source position transverse jitter [mm] < 5 Energy jitter pulse–to–pulse [%] < 0.2 # photons jitter pulse–to–pulse [%] ≤ 3 ELI-NP Source Specifications

8 GBS scheme: r.t. RF linac vs pulsed laserElectron beam parameter at IP Energy (MeV) 80-720 Bunch charge (pC) 25-400 Bunch length (µm) εn_x,y (mm-mrad) Bunch Energy spread (%) Focal spot size (µm) > 15 # bunches in the train ≤32 Bunch separation (nsec) 16 energy variation along the train 0.1 % Energy jitter shot-to-shot Emittance dilution due to beam breakup < 10% Time arrival jitter (psec) < 0.5 Pointing jitter (m) 1  Yb:Yag Collision Laser LE Interaction HE Interaction Pulse energy (J) 0.2 2x0.2 Wavelength (eV) 2.3,515 FWHM pulse length (ps) 3.5 Repetition Rate (Hz) 100 M2 ≤1.2 Focal spot size w0 (µm) > 28 Bandwidth (rms) 0.1 % Pointing Stability (µrad) 1 Sinchronization to an ext. clock < 1 psec Pulse energy stability 1 %

9 Based on the electron-photon collider approach:The rate of emitted photons is given by: 𝑁 𝛾 =𝐿 𝜎 𝑇 where: leading to: Laser 𝐿= 𝑁 𝐿 𝑁 𝑒 2𝜋 𝜎 𝑥 𝑤 e- 𝑁 𝛾 𝑠𝑒𝑐 −1 =4.1× 𝑈 𝐿 𝐽 𝑄 𝑝𝐶 𝑓 𝑅𝐹 𝑛 𝑅𝐹 ℎ 𝜈 𝐿 𝑒𝑉 𝜎 𝑥 2 𝜇𝑚 𝑤 𝜇𝑚 𝑐 𝜎 𝑡 𝛿 4 𝜎 𝑥 2

10 Within the desired bandwidth:Δ 𝜈 𝛾 𝜈 𝛾 ≅ 𝛾𝜗 ∆𝛾 𝛾 𝜀 𝑛 𝜎 𝑥 ∆ 𝜈 𝐿 𝜈 𝐿 𝑀 2 𝜆 𝐿 2𝜋𝑤 𝑎 0𝑝 𝑎 0𝑝 collimation system e- beam Laser system Courtesy of L. Serafini

11 Analytical model vs. classical/quantum simulationV. Petrillo Number of photons CAIN (quantum MonteCarlo) Run by I.Chaichovska and A. Variola TSST (classical) Developed by P. Tomassini bandwidth Comp_Cross (quantum semianalytical) Developed by V.Petrillo

12 The hybrid scheme for the Linac:Velocity bunching operation Long bunch at cathode for high phase space density : Q/n2 >103 pC/(µrad)2 Short exit bunch (280 µm) for low energy spread (~0.05%) Moderate risk (state of art RF gun, reduced multibunch operation problems respect to higher frequencies, low compression factor<3) Economic Compact (the use of the C-band booster meets the requirements on the available space)

13 Gamma Beam System – LayoutMaster clock synchronization @ < 0.5 ps e– beam dump Interaction Point High Energy e– beam dump Interaction Point Low Energy Photogun multibunch beam coll&diag beam coll&diag e– beam dump Racks Room Control Room Racks Room Interaction Laser High Energy e– RF LINAC High Energy 720 MeV Interaction Laser Low Energy Photo–drive Laser e– source e– RF LINAC Low Energy 300 MeV Courtesy of A. Variola

14 Accelerator Bay 1 – Layoutlaser beam circulator M9 300 MeV beam dump low energy interaction point switching dipole magnet C–band structures S–band structures Photogun

15 Accelerator Bay 2 – Layoutlaser beam circulator M26 high energy interaction point switching dipole magnet C–band structures low energy gamma beam diagnostics low energy collimator

16 Simulated gamma beams for different energiesEnergy [MeV] 2.00 3.45 9.87 19.5 # photons/pulse within FWHM bdw. < 1.2∙105 < 1.1∙105 < 2.6∙105 < 2.5∙105 # photons/s within FWHM bdw. < 4.0∙108 < 3.7∙108 < 8.3∙108 < 8.1∙108 Source rms size [mm] 12 11 10 Source rms divergence [mrad] ≤ 140 ≤ 100 ≤ 50 ≤ 40 Radiation pulse length rms [ps] 0.92 0.91 0.95 0.90

17 The IP Laser ricirculator

18 PARAMETERS = OPTIMIZED ON THE GAMMA-RAY FLUXOptical system: laser beam circulator (LBC) for J-class psec laser pulses focused down to mm spot sizes Electron beam is transparent to the laser (only 109 photons are back-scattered at each collision out of the 1018 carried by the laser pulse) Circulator principle PARAMETERS = OPTIMIZED ON THE GAMMA-RAY FLUX 2 high-grade quality parabolic mirrors Aberration free Mirror-pair system (MPS) per pass Synchronization Optical plan switching Constant incident angle = small bandwidth Laser power = state of the art Angle of incidence (φ = 7.54°) Waist size (ω0 = 28.3μm) Number of passes = 32 passes 30 cm 2.4 m F. Zomer K. Cassou

19 Laser pulse round-trip is about 16 nsecLaser pulse round-trip is about 16 nsec. A fresh electron bunch must be transported and focused at the IP every 16 nsec, for 32 round trips (total of 480 nsec -> need long flat RF pulse) g-ray beam time structure: micro-pulses carrying about 105 photons within the bandwidth (0.3%-0.5%) with 0.8 psec pulse duration, in trains of 32 micro-pulses, repeating at 100 Hz (10 msec train-to-train separation)

20 Technical solution: the dragon shape circulator

21 1 GeV e- beam for EUSPARC (6 more C-band sections)

22 Input and IP beam

23 Preliminary 𝛄-resultsCharge of the electron 250 pC laser sigz= um, laserwl=515.*nm, pulseE=0.4 J, sigLr=14.*micron, w0=2*sigLr, rayl=Pi*w0^2/laserwl, sigt=1.5*psec, angle=0,

24 bandwith analysis

25 Bandwidth analysis Collimated case Sigma_x=14 um Sigma_x=20 um