Thomson'Backsca,ering'Experiments'at'LOA' Andreas'Dpp' - - PowerPoint PPT Presentation

Thomson'Backsca,ering'Experiments'at'LOA'

HZDR,'Dresden,'April'2014' Andreas'Döpp' adoepp@clpu.es'

LA3NET TW3 : Novel Acceleration Techniques

X-rays in daily life X-rays in daily life

… ar … are b e based ased on Br

• n Bremsstrahlung and K-shell emission lines!

emsstrahlung and K-shell emission lines!

10 10 keV keV' 100 keV 100 keV' 1 MeV 1 MeV' Medical imaging Medical imaging' Industrial imaging Industrial imaging'

X-ray absorption X-ray absorption colour colour scale scale high high

• metal band (
• metal band (Zef

eff>18)

>18) medium medium

• inor
• inorganic band (

ganic band (Zef

eff>10)

>10) low low

• or
• organic band

ganic band (Zef

eff<10)

<10)

Airport security Airport security' Mammography Mammography'

Kα ( (42

42Mo) ~ 17.4

Mo) ~ 17.4 keV keV Kα'(45

45Rh) ~

Rh) ~ 20.1 20.1 keV keV

Dental radiography Dental radiography'

15-30 keV 15-30 keV'

CT scanner CT scanner'

~70 keV ~70 keV'

2

Ener Energy [10 keV] gy [10 keV]

X-rays in daily life X-rays in daily life

…have drawbacks due to br …have drawbacks due to broadband spectrum

• adband spectrum

3

Polychromatic X-ray produce artifacts in CT (beam hardening) Some advantages of (Quasi-) Monochromatic X-ray

• Better image contrast
• Less dose deposed in material
• Ideal for phase contrast imaging
• Ideal for dual-energy imaging

How do we get How do we get monoener monoenerget getic ic X-ray? X-ray?

Achterhold, K. et al.

• Sci. Rep. 3, (2013).

from : http://individual.utoronto.ca/s_richard/DEimaging.htm

Synchr Synchrotr

• tron rad
• n radiat

iation ion

4

Basic ideas :

• Frequency (ω) and trajectory (t) are coupled
• Sinusoidal trajectory sin ω0t should lead to some monoenergetic emission?
• Use doppler upshift to get high frequencies

How can we get an electron on a sinusoidal trajectory? Lor Lorentz For entz Force : ce :

• =
• +

×

• Pur

Purely electric ely electric Electr Electromagnet

• magnetic

ic Pur Purely magnet ely magnetic ic (magnet (magnetic insert ic insertion ion devices) devices) Compton / Thomson Compton / Thomson scat scattering tering (Plasma wave wiggler Plasma wave wiggler)

5

ħω0'

e-

λ’'= γL1'λ0 /'(1- β cos ϕ)' ϕ

~ 800 nm / 
 ~ 1.5 eV'

Doppler ef Doppler effect fect – moving receiver Angle between observer and electron direction (small angle approximation)

e-

θ – moving source

< 0.1Å / 
 > 10 keV'

'''''λ’’= λ’ x'(1- β cos θ) % %≈ λ0 x'(1+ γ2θ2) / 2γ2' Angle between ‘undulator’ and electron

Inverse Thomson Inverse Thomson Backscat Backscattering tering

(Opt (Optical) ical) Undulator Undulator equat equation ion =

• ( − ())
• +
• +

6

Strong motion in transverse plane effects longitudinal motion.

() +

• +
• () =

() Effective Lorentz factor γ’ = γ / (1+a0

2/2)1/2

a0 is equivalent to peak angular deflection parameter K.

Inverse Thomson Inverse Thomson Backscat Backscattering tering

(Opt (Optical) ical) Undulator Undulator equat equation ion =

• ( − ())
• +
• +
• Difference to K in conventional undulators :

a0 evolves during interaction

Inverse Inverse Thomson Thomson Backscat Backscattering tering

counter counter-pr

• propagat
• pagating u

ing using sing Plasma-Mirr Plasma-Mirror

• r

up to MeV range

7

Inverse Inverse Thomson Thomson Backscat Backscattering tering

counter counter-pr

• propagat
• pagating u

ing using sing Plasma-Mirr Plasma-Mirror

• r

8

Spherical Spherical mirr mirror

• r

(700 mm) (700 mm) ~ 50-55 % ~ 50-55 %

• f ener
• f energy in

gy in focal spot focal spot

~ 1.6 J, ~30 ~ 1.6 J, ~30 fs fs

(65 % of 2.5 J) (65 % of 2.5 J)

~ 0.9 J on tar ~ 0.9 J on target get

Lanex Lanex Scr Screen een Princeton Instruments Quad-RO: 4320

2084 x 2084 imaging array | 24um x 24um pixels

Inverse Inverse Thomson Thomson Backscat Backscattering tering

counter counter-pr

• propagat
• pagating u

ing using sing Plasma-Mirr Plasma-Mirror

• r

9

Reconstruct Intensity Pr Reconstruct Intensity Profiles

• files
• for free areas (holes)
• covered by 5.1mm Cu

Signal averaged to mean out local noise Interpolate signal using 2D cubic 2D cubic interpolat interpolation ion Background noise substracted Image Processing

Inverse Inverse Thomson Thomson Backscat Backscattering tering

counter counter-pr

• propagat
• pagating u

ing using sing Plasma-Mirr Plasma-Mirror

• r

10

Foil at the edge of Gas jet

Free 5mm Cu

50 100 150 200 250 0.5 1 1.5 2 2.5 3 3.5 x 107

140 MeV, 142 pC

Inverse Inverse Thomson Thomson Backscat Backscattering tering

counter counter-pr

• propagat
• pagating u

ing using sing Plasma-Mirr Plasma-Mirror

• r

11

Foil 12 mm behind edge of Gas jet Free 5mm Cu

101 pC

Inverse Inverse Thomson Thomson Backscat Backscattering tering

counter counter-pr

• propagat
• pagating u

ing using sing Plasma-Mirr Plasma-Mirror

• r

12

Filters show 50 % signal from < 100 keV From the electrons we miss on the spectrometer?

Simulation performed using 5000 test particles. ΔE/E=0.05. Divergence 5mrad. Scattering beam a0=1, 30 fs duration, 20 um FWHM.

Acknowledgements Acknowledgements

people | institutions | programs involved

13

Laboratoir Laboratoire d’Opt ’Optique ique Appl Appliquée iquée

Kim T Kim Ta a Phuoc Phuoc, Cedric , Cedric Thaury Thaury, , Emil Emilién ién Guil Guillaume, laume, Jean-Philippe Goddet, , Amar Tafzi, Remi Lehe, Igor Igor Andriyash Andriyash, Agustin Lifschitz, Victor ictor Mal Malka ka

Centr Centro de

• de Láser

Láseres es Pulsados Pulsados | Universidad de Salamanca | Universidad de Salamanca

Camilo Camilo Ruiz, Enrique Ruiz, Enrique Conejer Conejero

This work is funded is funded by the European Commission via LA3NET under contract PITN-GA-2011-289191