K. Z. Hatsagortsyan, G. Yu. Kryuchkyan*, A. Ipp, J. Evers and C. H. Keitel Max-Planck-Institut für Kernphysik, Heidelberg, Germany *Yerevan State University, Yerevan, Armenia "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 Employment of Bragg scattering for enhancement of vacuum polarization effects and of pair production for an ultra-short gamma-ray characterization 1

Outline "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011  Photon-photon scattering in a periodically modulated vacuum: Bragg scattering  Characterization of ultra-short pulses of γ-rays of GeV energies. Streaking method based on the strong field pair production: from femtosecond time-scale up to zeptoseconds. [SHEEP - streaking at high energies with electrons and positrons] FROG…..RABBITT…..SPIDER 2

Vacuum polarization/photon-photon scattering "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 Vacuum birefringence photon-photon scattering Second harmonic generation with Kaplan, Ding, PRA 2000 Di Piazza, KZH, Keitel, PRL 2005 Moulin et al. ZPC 1996 Bernard et al. EPJD 2000 Lundström et al. PRL 2006 M=0 in B=const Diffraction Uniform medium Nonuniform medium 3

Modulated vacuum: Bragg scattering "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 Bragg-scattering condition: 4

Bragg scattering vs. Photon-photon scattering "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 Lundström et al. PRL 2006 phase-matching factor Bragg-scattering condition: 5

Bragg scattering of light in vacuum with multiple laser beams Kryuchkyan, KZH, PRL 107, (2011) enhancement factor with respect to photon-photon scattering "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep z y

Outline "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011  Photon-photon scattering in a periodically modulated vacuum: Bragg scattering  Characterization of ultra-short pulses of γ-rays of GeV energies. Streaking method based on the strong field pair production: from femtosecond time-scale up to zeptoseconds. [SHEEP - streaking at high energies with electrons and positrons] 7

"PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 Time-resolved intra-nuclear dynamics MeV-GeV excitation energy Zeptosecond time-scale Pump Probe PumpProbe Quark system Why ultra-short pulses of GeV γ-rays are important? 8

Yoctosecond double pulses of γ-rays "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 A. Ipp, C. H. Keitel, J. Evers, PRL103, (2009) heavy-ion collisions 9

"PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 Characterization of ultra-short pulses Streak-camera 10

"PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 Streaking mechanism Conversion photons to electrons For hard x-rays 10 KeV - 1MeV: Compton ionization For XUV 100 eV - 1 KeV: Photoionization For γ-rays >MeV: e+e- pair production 11

Streak-camera for γ-rays via strong field e+e- pair production "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 Ipp, Evers, Keitel, KZH, PLB 702, 383 (2011) SLAC experiment D. Burke et al., PRL 79, 1626 (1997) 12

Streak-camera for γ-rays via strong field e+e- pair production "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 IP+SP should not create e+e- Fast oscillations due to IP Photoemission is negligible 13

Streak-camera for γ-rays: Parameters "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 Photoemission is negligible: 14

Streak-camera for γ-rays: GeV from fs up to zs resolution "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep

"PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 Conlcusion Bragg scattering can enhance photon-photon scattering A detection scheme has been proposed for the characterization of short γ-ray pulses in the GeV energy range based on pair creation. Sub-attosecond time resolution could be achieved with high-order harmonic generation in the upcoming ELI facility. 16

Thank you for your attention! "PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep