Diagnostics for high brightness electron beams Alessandro Cianchi

Diagnostics for high brightness electron beams Alessandro Cianchi University of Rome Tor Vergata & INFN Physics and Applications of High Brightness Beams 2016 Havana, Cuba

Outline Brightness Emittance State of the art Our ongoing work for One Shoot Emittance • Conclusion • • A. Cianchi Physics and Applications of High Brightness Beams 2

Definitions of Brightness Normalized Brightness [A/(m-rad)2] From diagnostics point of view what does it mean high brightness? A. Cianchi Physics and Applications of High Brightness Beams 3

Quad scan P 1 P 2 k 1 Beam k 2 k 3 Quadrupole We need at least 3 measurements in 3 different positions to evaluate the emittance A. Cianchi Physics and Applications of High Brightness Beams 4

Plasma acceleration Output beam LWA • LWA: Diagnostics of the output beam Input beam PWFA Output beam • PWFA: Diagnostics of both input (hopefully not intercepting) and output beam A. Cianchi Physics and Applications of High Brightness Beams 5

Train of bunches • COMB-like electron bunches are injected inside the preformed plasma. The first bunches create the wakefield, which is then seen from the last bunch (witness) which will be then accelerated • Challenge: creation and manipulation of driver bunches and matching all the bunches with the plasma • In order to fulfil this requirement a diagnostic of the single bunch is needed A. Cianchi Physics and Applications of High Brightness Beams 6

Time separation SCREENS … to the undulator Quadrupoles DIPOLE Seeding do … to the THz Source gleg Long Solenoids Beam energy 90 – 180 Me. V Bunch charge 50 – 500 p. C RF DEFLECTOR Rep. rate 10 Hz en < 2 mm-mrad sg 0. 05% - 1% Laser Pulse length 200 fs – 5 ps (FWHM) Paul Emma, Josef Frisch, Patrick Krejcik, A Transverse RF Deflecting Structure for Bunch Length and Phase Space Diagnostics, LCLS-TN-00 -12 Christopher Behrens, Measurement and Control of the Longitudinal Phase Space at High-Gain Free-Electron Lasers , FEL 2011, Shanghai A. Cianchi Physics and Applications of High Brightness Beams 7

Quad scan comb beam Time Space A. Cianchi Physics and Applications of High Brightness Beams 8

Results Bunch Driver #1 Witness Driver #2 Emittance (mm-mrad) Driver #1 1. 38 (0. 04) Driver #2 1. 61 (0. 07) Witness 1. 22 (0. 06) A. Cianchi et al. “Six-dimensional measurements of trains of high brightness electron bunches”, Physical Review Special Topics Accelerators and Beams 18, 082804 (2015) A. Cianchi Physics and Applications of High Brightness Beams 9

5 bunches Time Space A. Cianchi Physics and Applications of High Brightness Beams 10

Non-intercepting but multi shot Cianchi, A. , et al. "First non-intercepting emittance measurement by means of optical diffraction radiation interference. " New Journal of Physics 16. 11 (2014): 113029. Size it will be on I. Agapov, G. A. Blair, M. Woodley, Physical Review Special Topics Accelerators And Bemas 10, 112801 (2007) L. J. Nevay et al, Laserwire at the Accelerator Test Facility 2 with submicrometer resolution, Physical Review Special Topics Accelerators and Beams 17, 072802 (2014) A. Cianchi Physics and Applications of High Brightness Beams 11

Multiple OTR monitors • C. Thomas, N. Delerue and R. Bartolini “Single shot transverse emittance measurement from OTR screens in a drift transport section”, 2011 JINST 6 P 07004 ü In their case (3 Ge. V) the multiple scattering is not a factor for thin (5 mm) screens ü It is possible to produce even 1 mm aluminum screen ü This system seems not feasible for beams with energy in the range of hundreds of Me. V ü A waist is a must P. Castro, “Monte Carlo simulations of emittance measurements at TTF 2”, Desy Technical-Note-03 -03 A. Cianchi Physics and Applications of High Brightness Beams 12

Pepper-pot like structures To measure the emittance for a space charge dominated beam the used technique is the well known 1 -D pepper-pot The emittance can be reconstructed from the second momentum of the distribution C. Lejeune and J. Aubert, Adv. Electron Phys. Suppl. A 13, 159 (1980) A. Cianchi Physics and Applications of High Brightness Beams 13

High energy pepper pot • In principle can operate also at moderate to high energy (500 Me. V- 1 Gev) • Length 50 mm, slit 500 mm, spaced 2 mm N. Delerue Nuclear Instruments and Methods in Physics Research A 644 (2011) 1– 10 C. Thomas, N. Delerue, R. Bartolini, Nuclear Instruments and Methods in Physics Research A 729 (2013) 554– 556 A. Cianchi Physics and Applications of High Brightness Beams 14

Pepper pot fans A. Cianchi Physics and Applications of High Brightness Beams 15

Intrinsic limit for LWFA beams • No considerations about – S/N ratio – Detector – Multiple scattering – Background • Mask thickness neglected • The phase space is so thin that the sampling is very inefficient especially in angle Cianchi, A. , et al. "Challenges in plasma and laser wakefield accelerated beams diagnostic. " NIM A 720 (2013): 153 -156. A. Cianchi Physics and Applications of High Brightness Beams 16

Betatron radiation A. Rousse et al. “Production of a ke. V X-Ray Beam from Synchrotron Radiation in Relativistic Laser-Plasma Interaction”, PRL 93, 135005 (2004) Picture from F Albert et al Plasma Phys. Control. Fusion 56 (2014) 084015 A. Cianchi G. R. Plateau and al. , Low-Emittance Electron Bunches from a Laser-Plasma Accelerator Measured using Single. Shot X-Ray Spectroscopy, PRL 109, 064802 (2012) Physics and Applications of High Brightness Beams 17

s s’ g Dg at the same time • S. Kneip and al. , PRST-AB 15, 021302 (2012) Source size by Fresnel diffraction A. Cianchi Energy, energy spread and divergence behind the dipole Physics and Applications of High Brightness Beams 18

A new kind of Quadscan • R. Weingartner and al. , PRST-AB 15, 111302 (2012), A. Cianchi Physics and Applications of High Brightness Beams 19

Transition radiation Electron beam Metallic screen Beam splitter Beam imaging system angular distribution A. Cianchi Physics and Applications of High Brightness Beams 20

Effect of angular spread A. Cianchi Physics and Applications of High Brightness Beams 21

Visibility vs Energy Visibility vs energy 1. 0 0. 9 Visibility 0. 8 100 urad 125 urad 150 urad 200 urad 300 urad 400 urad 500 urad 0. 6 0. 4 0. 2 0. 0 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 g A. Cianchi Physics and Applications of High Brightness Beams 22

Resolution vs Energy A. Cianchi Physics and Applications of High Brightness Beams 23

Wartsky interferometer • • C. Couillaud, A. Loulergue, G. Haouat, ”ELECTRON BEAM TRANSVERSE EMITTANCE MEASUREMENT USING OPTICAL TRANSITION RADIATION INTERFEROMETRY”, Proceedings of Epac 96, Spain Feldman, R. B. , et al. "Developments in on-line, electron-beam emittance measurements using optical-transition radiation techniques. " NIMA: 296. 1 (1990): 193 -198 A. Cianchi Physics and Applications of High Brightness Beams 24

Further improvement Electron beam Metallic screen Beam splitter Beam imaging system Image plane + mask angular distribution A. Cianchi Physics and Applications of High Brightness Beams 25

With a mask G. P. Le Sage, T. E. Cowan, R. B. Fiorito, and D. W. Rule, ”Transverse phase space mapping of relativistic electron beams using optical transition radiation” , PHYSICAL REVIEW SPECIAL TOPICS - ACCELERATORS AND BEAMS, VOLUME 2, 122802 (1999) A. Cianchi Physics and Applications of High Brightness Beams 26

Micro lens array A. Cianchi Physics and Applications of High Brightness Beams 27

Electron beam Metallic screen Beam splitter Beam imaging system + High. QE CCD Microlens array Imaging of the microlens focal plane Intensified camera, angular distribution A. Cianchi Physics and Applications of High Brightness Beams 28

Flexibility • It is possible to work on the magnification of the beam size at the microlens position to increase the sampling rate • The magnification decreases the angular spread of the radiation but it does not change the visibility of the fringes because it comes from the beam at the OTR screen position • At the same time the magnification of the microlens array pattern allows to resolve small angles A. Cianchi Physics and Applications of High Brightness Beams 29

Optical setup CCD Beam splitter CCD Intensified camera Movable mirror Lens Microlens array A. Cianchi Physics and Applications of High Brightness Beams 30

Zemax simulations Courtesy by F. Bisesto A. Cianchi Physics and Applications of High Brightness Beams 31

2 D A. Cianchi Physics and Applications of High Brightness Beams 32

Beam and OSE signal A. Cianchi Physics and Applications of High Brightness Beams 33

Different shape A. Cianchi Physics and Applications of High Brightness Beams 34

Analysis of a single ring A. Cianchi Physics and Applications of High Brightness Beams 35

Conclusions • High brightness beam diagnostics is very challenging especially for emittance measurements • Well established methods are available for input beams even in case of comb like structure • A lot of work must be dedicated for output beams • We have just started to understand how to measure it with a new system A. Cianchi Physics and Applications of High Brightness Beams 36

Finally it’s over Thank you for your attention A. Cianchi Physics and Applications of High Brightness Beams 37

holder A. Cianchi Physics and Applications of High Brightness Beams 38

Features A. Cianchi Physics and Applications of High Brightness Beams 39

A possible case A. Cianchi Physics and Applications of High Brightness Beams 40

Better at 200 Me. V! A. Cianchi Physics and Applications of High Brightness Beams 41