Gamma-ray vortex generation by inverse Compton scattering

Transcription

1 JLab Seminar 12/12/216 Gamma-ray vortex generation by inverse Compton scattering Yoshitaka Taira National Institute of Advanced Industrial Science and Technology (AIST), Japan Visiting scientist: Mississippi State University and Jefferson Lab.

2 Outline Vortex beams carrying orbital angular momentum Gamma-ray vortex generation 1 Frequency upconversion of an optical vortex laser by inverse Compton scattering (ICS) 2 Nonlinear ICS of intense circularly polarized laser (not vortex laser) Summary Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 1

3 Optical vortex Transverse profile Interference pattern Forming a helical wave front. E exp i φ ( ) Carrying orbital angular momentum (OAM) Total AM = OAM + spin AM = lħ + ħ M. Padgett et al., Phys. Today 57 (24) 35. Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 2

4 Generation Special filters Cylindrical lens Spiral phase plate Hologram J. Courtial et al., Opt. Comm. 159 (1999) 13. M. W. Beijersbergen et al., Opt. Comm. 112 (1994) 321. Without filters Electron Vortex beam Electromagnetic radiation from an electron Main topic of this talk Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 3

5 Vortex beams Radiation Type Wavelength (m) Radio Microwave Infrared Visible Ultraviolet X-ray Gamma ray Approximate Scale of Wavelength Buildings Humans Butterflies Needle Point Protozoans Molecules Atoms Atomic Nuclei Frequency (Hz) Micro/THz wave Laser 1 kev X-ray Except for the electromagnetic wave 3 kv electron Cold neutron Wikipedia. Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 4

6 Application of vortex beams Experimental demonstration OAM transfer to micro particle φ 1 µm 3x1.5 µm Quantum entanglement Creation of metal nano needle Terabit data transmission Theoretical proposal X-ray dichroism Magnetic mapping using electron vortex Direct observation of rotating black hole Excitation of atom A. T. ONeil et al., Phys. Rev. Lett. 88 (22) Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 5

7 Review articles Journal papers M. Padgett, J. Courtial, and L. Allen, Phys. Today 57 (24) 35. G. M. Terriza, J. P. Torres, and L. Torner, Nat. Phys. 3 (27) 35. S. F. Arnold, L. Allen, and M. Padgett, Laser & Photon. Rev. 2 (28) 299. A. M. Yao and M. J. Padgett, Adv. Opt. Phot., 3 (211) 161. Books L. Allen et al., Optical Angular Momentum IoP publishing, 23. A. Bekshaev et al., Paraxial Light Beams with Angular Momentum Nova Science Publishers, 28. D.L. Andrews, Structured Light and its Applications Academic Press, 28. J. P. Torres and L. Torner, Twisted Photons Wiley-VCH, 211. D.L. Andrews and M. Babiker, The Angular Momentum of Light Cambridge University Press, 213. Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 6

8 Outline Vortex beams carrying orbital angular momentum Gamma-ray vortex generation 1 Frequency upconversion of an optical vortex laser by inverse Compton scattering (ICS) 2 Nonlinear ICS of intense circularly polarized laser (not vortex laser) Summary Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 7

9 Purpose Generation of gamma ray vortex (> MeV) and development its application. Radiation Type Wavelength (m) Radio Microwave Infrared Visible Ultraviolet X-ray Gamma ray Approximate Scale of Wavelength Buildings Humans Butterflies Needle Point Protozoans Molecules Atoms Atomic Nuclei Frequency (Hz) Gamma-ray Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 8

10 Application possibility Insight into the proton structure I. P. Ivanov, Phys. Rev. D 83 (211) 931. u Gamma ray vortex d u If the OAM of gamma ray is transferred to the quark/gluon, it becomes novel probe of the proton spin. Nuclear physics Y. Taira et al., arxiv 168 (216) Excited states can be populated by high order transition. Photon-induced reaction cross section will be changed. Generation of positron vortex via pair production As a new particle source for high energy physics. Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 9

11 Compton scattering Incident photon ω ω'/ω Electron at rest Photon energy Recoil electron θ Scattered photon ω' ω =.1 MeV ω =.1 MeV ω =.5 MeV ω = 3. MeV ω ω' = ω 1+ m e c d dω dσ/dω/r 2 = ( 1 cosθ ) σ r 2 ω' ω' ω + sin θ 2 ω ω ω' Cross section Thomson scattering θ (rad) θ (rad) Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 1

12 Inverse Compton scattering (ICS) Laboratory frame Relativistic electron γ Scattered photon ω' Incident photon ω θ Electron rest frame Scattered photon ω' ER ER θ Electron at rest Incident photon ω ER ICS can be derived by the Lorentz transformation of the Compton scattering. ω ER = γ (1 + β ) ω = 6.2 kev < c m e 2 = 511 kev Thomson scattering when γ = 2 and ω = 1.5 ev Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 11

13 Energy and Spatial distribution 25 E γ (MeV) θ (mrad) Linear polarization 2 1 γ = 2 ω = 1.55 ev (λ = 8 nm) Circular polarization 2 1 γ sinθ sinφ γ sinθ sinφ γ sinθ cosφ γ sinθ cosφ Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 12

14 Outline Vortex beams carrying orbital angular momentum Gamma-ray vortex generation 1 Frequency upconversion of an optical vortex laser by inverse Compton scattering (ICS) U. D. Jentchura et al., PRL 16 (211) 131. V. Petrillo et al., PRL 117 (216) Nonlinear ICS of intense circularly polarized laser (not vortex laser) Summary Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 13

15 1 γ ICS of optical vortex laser θ Plane wave electron Optical vortex laser Gamma-ray vortex It was predicted that OAM of the gamma-ray preserved the OAM of the laser at the very small angle θ < 1/γ 2. U. D. Jentchura et al., PRL 16 (211) 131. It was indicated that the spatial distribution of the X-ray vortex become annular profile in the case of γ = 5. V. Petrillo et al., PRL 117 (216) Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 14

16 Spatial distribution of E 2 of X-ray vortex y (mm) y (mm) γ = x (mm) γ = x (mm) y (mm) Intensity (arb. unit) γ = x (mm) γ = 5 γ = 1 γ = x (mm) Laser Linearly polarized (y direction). OAM = 1ħ The diameter of the ring does not depend on the electron energy? Further calculation is needed. V. Petrillo s calculation code was used. Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 15

17 Experimantal demonstration JLab Compton polarimeter at Hall A and C Fabry-Perot cavity Wavelength: 532 nm Stored power: 1 W To exceed background, more than 1 W vortex laser is required. We can do the experiment by replacing the normal laser with vortex laser. T. Allison et al., NIMA 781 (215) 15. Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 16

18 Measurement technique of vortex laser Interferometer Iris CCD Lens f1 Reference light (Plane or spherical wave) Vortex light Neutral density filter Iris Beam splitter Laser Holographic fork grating l= 2 1 mm Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 17

19 Interference pattern OAM value Plane wave + vortex 2 Split Spherical wave + vortex 1 spiral 1 3 Split 2 spiral 2 Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 18

20 Optical cavity test of vortex laser CCD ND filter 84 mm Cavity mirror Reflection = 99.1 % Curvarture = 5 mm φ = 7.75 mm Lens f5 Vortex light Reference light Laser Grating Iris Note: two cavity mirrors are not controlled by any feedback system. Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 19

21 Observation of good results Spatial distribution after cavity Interference pattern (l=1) Next step: Mode locking, estimation of storing power, etc.. Fork pattern was observed! Not the whole time, sometime no fork pattern. Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 2

22 Outline Vortex beams carrying orbital angular momentum Gamma-ray vortex generation 1 Frequency upconversion of an optical vortex laser by inverse Compton scattering (ICS) 2 Nonlinear ICS of intense circularly polarized laser (not vortex laser) Summary Y. Taira et al., arxiv 168 (216) Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 21

23 Helical motioned electron emits vortex beam X-ray vortex generation using helical undulator was proposed by S. Sasaki in 28. Electron in helical motion Vortex beam Transverse motion produces higher harmonics. Higher harmonics carry OAM of (n-1)ħ. S. Sasaki et al., PRL (28). Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 22

24 UV measurement at UVSOR-III, Japan λ = 355 nm 2nd harmonics 3rd harmonics 1 spiral OAM = 1ħ 2 spiral OAM = 2ħ M. Katoh et al., arxiv (216). Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 23

25 2 Nonlienar ICS induces helical motion Nonlinear effect of the laser (a laser strength parameter, a 1) induces helical motion of the electron. Gamma-ray vortex Electron Circularly polarized laser Scaling of the emitted wavelength Helical undulator Nonlinear ICS Period of helical motion Wavelength of emitted photon cm Visible to soft X-ray 1 4 µm Hard X-ray to Gamma-ray Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 24

26 Gamma-ray energy Electron γ θ Gamma-ray vortex ω' Circularly polarized laser ω a ω' = 2 8nγ ω 2 2 2γ θ a 2 Gamma ray energy (MeV) a =.1 a =.5 a = 1. a = 2. γ = 2 ω = 1.24 ev n = γ θ Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 25

27 Electric field and Stokes parameter Electric field in the x-y plane E + Degree of circular polarization γ sinθ sinφ = i 2 3 i 2 ( C cosθ + C ) exp iψ + ikr + i( n 1) 1 { φ} ( C cosθ C ) exp iψ + ikr + i( n + 1) θ θ φ φ { φ} e γ sinθ cosφ Y. Taira et al., arxiv (216). Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 26 e ± e x ± ie y = 2 Positive helicity carry (n-1)ħ OAM Negative helicity carry (n+1)ħ OAM. Positive helicity (n-1)ħ OAM Negative helicity (n+1)ħ OAM e +

28 Why does gamma-ray carry (n±1)ħ OAM? Quantum theory of nonlinear ICS e + nγ L e + γ Electron absorbs circularly polarized n photons and emits circularly polarized one photons. n is the harmonic number. Conservation of total angular momentum of the photon Helicity of emitted photon Before interaction SAM OAM Total After interaction SAM OAM Total Positive +n +n +1 n-1 +n Negative +n +n -1 n+1 +n Under the assumption SAM and OAM can be separated each other. Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 27

29 Spatial distribution γ sinθ sinφ γ sinθ cosφ n =1 n =2 γ sinθ sinφ γ sinθ cosφ γ sinθ sinφ 3-3 n =3-3 3 γ sinθ cosφ Annular shape of higher harmonic is due to the helical wavefront. Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 28

30 Characteristics of nonlinear ICS gamma-ray Helicity Positive Negative Fundamental (n = 1) N 6 x 1 1 photons/sec 2 x 1 1 photons/sec E MeV MeV OAM 2nd harmonics 2ħ N 2 x 1 1 photons/sec 2 x 1 1 photons/sec E MeV MeV OAM ħ 3ħ a = 1., λ = 1. µm, γ = 2, N e =1 9 electrons/sec Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 29

31 Second harmonic X-rays at BNL (a =.6) Electron γ = 128 Circularly polarized laser X-ray vortex 1 λ = 1.6 µm, pulse energy = 2 J, 2ω = 1 µm, pulse width = 5 ps (FWHM) Calculation (Y. Taira) 1 Measurement (BNL) Y (mm) This will be the X-ray vortex X (mm) E = 13 kev (λ =.95 nm) Y. Sakai et al., PRSTAB (215). Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 3

32 Helical wavefront measurement Oncoming X-ray X-ray 15 µm few µm tungsten wire Top view Detector (1.85 m from source) X-ray 15 µm Wire.5 m Interference pattern between X-ray vortex and diffracted X-ray from the wire. 3 σ = µm σ = 2 µm Y (µ m) Y (µ m) σ: rms beam size of the electrons X (µ m) X (µ m) -1 Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 31

33 Conclusion Gamma ray vortex providing an additional degree of freedom will open new research opportunities! Gamma-ray vortex can be generated by the inverse Compton scattering. Measurement of gamma ray vortex is a big issue. Interferometry, Dichroism, and Pair production are candidates. Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 32

34 Acknowledgement JSPS Postdoctoral Fellowships for Research Abroad. Dipangkar Dutta (Mississippi State University). Joseph Grames, Shukui Zhang, Dave Gaskell, Matthew Poelker, Geoffrey Krafft, Riad Suleiman, John Hansknecht, Andrew Hutton (Jefferson Lab). Vittoria Petrillo (Università degli Studi di Milano). Benjamin McMorran (University of Oregon). Masahiro Katoh (IMS). Takehito Hayakawa (QST). Group member of Radiation Imaging Measurement Group at AIST. Andrei Afanasev (George Washington University). Daniel Seipt (Helmholtz Institut Jena). Valeriy Serbo (Novosibirsk State University). Thank you for your attention! Y. Taira, Gamma-ray vortex generation by inverse Compton scattering 33