Outline 1.ERL facility for gamma-ray production [A. Valloni] 2.ERL facility - Tracking Simulations [D. Pellegrini] 3.SC magnet quench tests [V. Chetvertkova]

GAMMA BEAM PRODUCTION AT THE ERL FACILITY Alessandra Valloni LHeC meeting

Compton inelastic back-scattering Incident laser beam Incident electron beam Scattered laser beam The energy of the photons after the collision can be approximated as Electron recoil parameter Vector potential associated to the laser e.m. field (laser parameter)

Compton inelastic back-scattering Incident laser beam Incident electron beam Scattered laser beam In order to maximize the energy of the scattered photon - counter-propagating beams - head-on collision a 0 and the recoil parameter << 1 for relativistic electrons this means a gain in the energy of the photons of more than one million times

Gamma-ray energies can be selected by changing the : -electron energy -laser wavelength -and collision angle To generate high-flux and high-brightness gamma-rays: -High brightness, small emittance and low energy spread electron beams -Brilliant and high repetition lasers -Small collision volume at the interaction point ensuring the spatial and temporal overlap of the electron beam and the laser Compton sources can be considered as electron-photon colliders For a generic source there are four important quantities that characterize the source: - the total number of scattered photons per second over the 4π solid angle -the rms source bandwidth -the number of photons per second in the bandwidth -the spectral density Characteristics of the Gamma photon beam

Total number of scattered photons per second over the 4π solid angle and the entire energy spectrum (from the minimum energy ν up to the maximum one) Collision repetition rate Electron/laser spot size Energy carried by the laser pulse Electron bunch charge rms bandwidth of the emitted photons can be calculated by normalized collecting angle electron bunch energy spread laser pulse bw Since the e- beam has divergence at the IP, different e- collide with photons at different angles  gamma energy spread

Characteristics of the Gamma photon beam Number of photons per second in the bandwidth for small normalized collecting angles γθ << 1 Spectral density, defined by the ratio between the number of photons in the bandwidth and the rms value of the bandwidth

Electron and laser beams at ELI-NP 720 MeV 250 pC 0.5 um 15 um 0.1%

Gamma beam at ELI-NP

Electron and laser beams at the ERL facility ELECTRON BEAM PARAMETERS Energy900 MeV Charge320 pC Spot size30 um Norm. Trans. Emittance1.5 um Energy Spread0.1 % LASER BEAM PARAMETERS 1* Wavelength1030 nm Average Power600 kW Pulse length3 ps Pulse energy15 mJ Spot size30 um Bandwidth0.02 % Repetition Rate40 MHz LASER BEAM PARAMETERS 2* Wavelength515 nm Average Power300 kW Pulse length3 ps Pulse energy7.5 mJ Spot size30 um Bandwidth0.02 % Repetition Rate40 MHz *Parameters suggested by Fabian Zomer

Gamma beam energy at the ERL facility Maximum Gamma Energy ≈ 15 MeVMaximum Gamma Energy ≈ 30 MeV

Total number of scattered photons Characteristics of the Gamma photon beam at the ERL facility (1) Wavelength1030 nm Average Power600 kW Pulse energy15 mJ Number of photons produced per electron Number of photons per second in the bandwidth Spectral density Spectral Brightness

Total number of scattered photons Characteristics of the Gamma photon beam at the ERL facility (2) Number of photons produced per electron Number of photons per second in the bandwidth Spectral density Spectral Brightness Wavelength515 nm Average Power300 kW Pulse energy7.5 mJ

Gamma beam at ELI-NP / ERL facility ≈ 30 MeV ≈ 8*10^5 ≈ 10^10 ≈ 10^22

QUESTIONS ??????

Where could it be installed? - Add an additional arc - Add additional space downstream of linac 2 (longer straight line)

How much space do we need? -Focusing line up to the IP -Line for Gamma beam collimation and characterization

For which applications?

..are we including this topic in the CDR???* *F. Zomer (& his group) offered his collaboration to write few pages on the laser system for Compton back-scattering

Thank you for your attention