Title OTR based measurements for ELINP Gamma Beam

Title OTR based measurements for ELI-NP Gamma Beam Source Supervisor: L. Palumbo Co-Supervisor: A. Mostacci M. Marongiu 2018/11/19 Accelerator Physics Doctorate OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Outline § Gamma Beam System (GBS) main parameters § Optical Transition Radiation (OTR) properties § Photons Evaluation § Mechanical Analysis • Thermal issues • Fatigue Stress § Beam Imaging • Lens Characterization • Magnification • Resolution • Test Stand for Lens Calibration § Bunch by Bunch Measurements § Gated Camera System Characterization § Optical Transport (Zemax) • Optical Design • OTR Simulations 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Gamma Beam System Layout Beam Screens Electron Beam Parameters Max. Energy at IP [Me. V] 280 – 720 Macro Pulse rep. Rate [Hz] 100 Number of bunches up to 32 Bunch spacing [ns] 16. 1 Bunch length [ps] 0. 91 Bunch charge [p. C] 25 -250 εn_x, y [mm·mrad] 0. 2 -0. 6 Bunch Energy Spread < 0. 1% 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Linac diagnostics Beam Screens Non-intercepting diagnostics: Intercepting diagnostics: Charge measurements: • 4 Integrating Current Transformers (bunch by bunch) Phase-Space measurements: • 23 Beam Screens (YAG and OTR) Position measurements: • 29 stripline BPMs (Macro pulse) • 4 cavity BPMs (bunch by bunch) • Beam Loss Monitor System 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Transition Radiation Properties § Transition Radiation (OTR) screens are widely used for profile measurements § The radiation is emitted when a charged particle beam crosses the boundary between two media with different optical properties § The visible part of the radiation is often used (transverse diagnostic) and an observation geometry in backward direction is mainly chosen x y § Advantages • Instantaneous emission (~fs) • Linearity (neglecting coherent effect) § Disadvantages • The process of radiation generation is invasive • The radiation intensity is lower in comparison to scintillation screens (1 E-5) θy θx 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Photons Evaluation M=1 M=2 48 x 109 µm; 234 Me. V; 250 p. C M=3 M. Marongiu, et al. , Proceedings of IBIC 2017 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Thermal Analysis OTR 32 bunches, 250 p. C each y x 2018/11/19 M. Marongiu, et al. , Proceedings of “Physics and Applications of High Brightness Beams”, 2016 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Fatigue Stress 102 minutes Equivalent Von Mises Stress (Pa) F. Cioeta, et al. , Proceedings of IPAC 2017 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Camera lens test-bench Camera Lens 180 mm lens with teleconverter (2 x) 180 mm lens 180 mm w/o teleconverter (2 x) 105 mm w/o teleconverter (2 x) 180 mm lens with teleconverter (1. 4 x) The resolution is 1/x (mm). The sizes of each horizontal line are 2, 5/x for the length and 1/(2 x) for the width (mm) and vice versa for the vertical lines. M. Marongiu, et al. , Proceedings of IPAC 2017 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Camera lens Results Camera Lens 180 mm w/o teleconverter (2 x) 105 mm w/o teleconverter (2 x) 1: 8 Screen (3 cm) 100µm 1: 2 Beam (1 mm) 105 mm with teleconverter (2 x) 180 mm with teleconverter (1. 4 x) 180 mm with teleconverter (2 x) 2018/11/19 M. Marongiu, et al. , Proceedings of IPAC 2017 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Gaussian Reconstruction • 5 Samples • Error ~7% If Resolution=30µm and σ>19µm If σ=10µm and Resolution<16µm • 8 Samples • Error ~4% If Resolution=30µm and σ>30µm If σ=10µm and Resolution<10µm • 20 Samples • Error <<0, 01% If Resolution=30µm and σ>75µm If σ=10µm and Resolution<4µm M. Marongiu, et al. , Proceedings of IPAC 2017 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Single Bunch Measurements 82%@550 nm Gated Intensified Camera CCD saturation effects on spot size measurements • • @ SPARC 46% for Basler sc. A 640 -70 gm • • • Revolution Frequency @ DAFNE: 3 MHz Electron Beam: 108 bunches; 650 m. A; 250µm Synchrotron light: 1 E 20 photons/turn T. exp. =20 ms Measurements @ DAFNE 2018/11/19 Gate: 6 ns OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Energy Measurements SPF @ SPARC ~ 120 Me. V ~ 120 p. C 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Data Analysis V. Verzilov, Private Communication Data Set 2 Measurements @ SPARC 2018/11/19 M. Marongiu, et al. , Proceedings of “European Advanced Accelerator Concepts Workshop”, 2017 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Zemax Simulation (Single Particle) SPF 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Zemax Simulation - (Collective effects) Simulation Theory Data @ SPARC M. Marongiu, et al, WEPAL 013, Proceedings of IPAC 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Zemax Simulation – Energy Spread 0. 1% 1% 10% 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Zemax Simulation – ELI-NP-GBS Case Uncorrelated Beams Screen 1 Screen 2 Unorrelated Beams: Perfect agreement with theory Screen 5 Correlated Beams: • Additional contribution in the divergence parameter • Increase of the fit uncertainty A. Giribono 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Conclusion § Gamma Beam System (GBS) main parameters § Optical Transition Radiation (OTR) properties § Photons Evaluation § Mechanical Analysis • Thermal issues • Fatigue Stress § Beam Imaging • Lens Characterization • Magnification • Resolution § Bunch by Bunch Measurements § Gated Camera System Characterization § Optical Transport (Zemax) • OTR Simulations 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza

Thank you for your attention! 2018/11/19 OTR based measurements for ELI-NP Gamma Beam Source Marco Marongiu, Sapienza