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

B

Vacuum polarization/photon-photon scattering

"PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011

Vacuum birefringence

photon-photon scattering

ConstF

Second harmonic generation with Kaplan, Ding, PRA 2000 Di Piazza, KZH, Keitel, PRL 2005

0F

crEE

fi kk

Moulin et al. ZPC 1996Bernard et al. EPJD 2000Lundström et al. PRL 2006

M=0 in B=const

Diffraction

Uniform medium

Nonuniform medium

ik fk

3

Modulated vacuum: Bragg scattering

"PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011

Bragg-scattering condition: nSind 2q

4

B012 qnkk

Bragg scattering vs.Photon-photon scattering

26

4~ Cm

"PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011

V

mE

EmNjW

crsp

64

4212 ~~

88

22 VEN

Ej

V

kE

EmWW

crspstim 3

36

43 ~~

0

1~

wk

320

32

30 ~~ 12 VRrdeRW qkki

Bragg

z

stim

Bragg L

W

W ~

Lundström et al. PRL 2006

phase-matching factor

Bragg-scattering condition:

k

Ek

3

2

8

5

yxLLk 2/1~

Bragg scattering of light in vacuum with multiple laser beams

Kryuchkyan, KZH, PRL 107, 053604 (2011)

enhancement factor with respect to photon-photon scattering

"PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011

102

1

3;13 3

23

N

N

N

N

II

II

stim

BraggtotBragg

totstim

shotNfscmW ph /5100/103 222

6

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 energyZeptosecond time-scale

Pump

Probe

PumpProbeQuark 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, 152301 (2009)

heavy-ion collisions

9

"PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011

Characterization of ultra-short pulsesStreak-camera

10

"PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011

Streaking mechanismConversion 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

mc

eE

m

Nm

N

Nem

N

iti

itt

ee

itt

ee

3

82

1,

1,

2

3/22

3/82/32

tt ,/1

tsSN /

crsi EEE ,

si

1ii

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

303,1011 iiii Photoemission is negligible:

titi

m

3

822

stsSN /

t 1.0~// ttists

14

Streak-camera for γ-rays: 0.3-30 GeVfrom fs up to zs resolution

"PW Lasers at Hard X-ray Sources" Dresden-Rossendorf, 7 Sep 2011 15

"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 2011 17