polarization and correlation phenomena in relativistic ......projectile x-ray emission following...

Polarization and correlation phenomena in relativistic atomic collisions

Andrey SurzhykovUniversity of Heidelberg and GSI, Darmstadt

in collaboration withStephan Fritzsche, Nikolai Kabachnik, Alexander Gumberidze and Thomas Stöhlker

Work is supported by Helmholtz association

426. WE-Heraeus-Seminar 21 January 2009

Atomic physics of highly-charged, heavy ions


During the last decade, atomic physics studies with highly-charged heavy ions have attracted much of interest both in experiment and theory.

Heavy ions provide a unique tool for investigation ultra-strong and ultra-short electromagnetic interactions.

( )2/1

1

cv=γ

−

E ≈ 1016 V/cm

Intense Laser

“structure” studies “collision” studies... and their interplay!

Characteristic x-ray emission from high-Z ions Ion storage rings Electron beam ion traps

1st step: formation of excited state

2nd step: radiativedecay

excited state

A large number of studies have been performed at the storage ring and EBIT facilities to explore projectile x-ray emission following ion-atom collisions.

Analysis the subsequent x-ray emission provides important information both on the structure and on the dynamics of highly-charged heavy ions.


Alignment of excited ionic states

In ion-atom collision experiments a preferred direction for the overall system is defined by the ion direction.

Residual (excited) ion may appear to be aligned along this direction.

Example: alignmentof J=1 state

Alignment is described by set of alignment parameters.

These parameters (together with the structure parameters) determine the properties of the subsequent radiative decay.

01

012 2

2σσ

σσ+

−=

±

±A

MJ = -1 MJ = 0 MJ = +1

target atom

projectile ion


Characteristic radiation: Analysis

We have performed a polarization and angle-resolved analysis of the characteristic x-ray radiation from highly-charge ions following:


θ

Coulomb excitationRadiative electron capture Dielectronic recombination

1stst

ep2n

dst

ep

Radiative decay following REC of bare ions

2p3/2

fitting

)(cosP1 2 θβ+

Ani

sotr

opy

para

met

er β

E1+M2

If multipole mixing between E1 and M2 decay channels is taken into account:

Where f(E1, M2) is the “structure function”:

221 A=β )2,1(

21

2 MEfA=β

12321)2,1(EMMEf +≈

A.S. et al., PRL 88 (2002) 153001


Radiative decay following REC of H-like ions

1s1/2 2p3/2

observation angle q [deg]

Ka1

Ka2

Kα1

Kα2

In contrast to Lyman-α1 decay in H-like ions, Kα1 emission in He-like ions was found to be almost isotropic.

U90+

Tp = 220 Mev/u




1s1/2 2p3/2

E1

M2

In contrast to Lyman-α1 decay in H-like ions, Kα1 emission in He-like ions was found to be almost isotropic.

This isotropy is the results of “E1-M2” cancellation in He-like systems:

A.S. et al., PRA 74 (2006) 052710E. Drukarev et al., PRA 74 (2006) 022717

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛−+⎟

⎠

⎞⎜⎝

⎛ +∝ )(cosP)(1451)(cosP)(

211 22

32221

1211

θθθ α PANPANW K

E1 decay M2 decay

U90+ @ Tp = 220 Mev/u



E1

M2

Another sequence of the “E1-M2” cancellation is the depolarization of Kα1 radiation.

A.S., Th. Stöhlker and S. Fritzsche, NIMB in press

Tp = 10 MeV/u Tp = 220 MeV/u Tp = 400 MeV/u

+ =

M2

E1

Kα1

gas

t

arge

t

ion beam

Reacti

on plane

900

900

IIIIPL +

−=




θ

1stst

ep2n

dst

ep


Radiative decay following excitation of He-like ions

Inte

nsity

ratio

Kα

1/Kα

2

Tp =217 MeV/u1s1/2 2p3/2

Coulomb excitation of He-like U90+

A.Gumberidze. et al., Hyperfine Int. 146/147 (2003) 133

fit of experimental data

Kα1 radiation following Coulomb excitation of He-like ions exhibits strong anisotropy.


Radiative decay following excitation of He-like ions

Kα1 radiation following Coulomb excitation of He-like ions exhibits strong anisotropy.

A.S., U. Jentschura, S. Fritzsche and Th. Stöhlker, PRA 77 (2008) 042722

theoryexperiment

Tp =217 MeV/u

1s 2p3/2 21P1

1s 2p3/2 23P2

Coulomb excitation leads to an almost exclusive population of 21P1 level.

Only E1 transition contributes to Ka1 decay:

( ) )()( 22111θθθ α MEK WNWNW +∝


Radiative decay following excitation of He-like ions1s 2p3/2 21P1 Calculations of the alignment of the He-like ions

following Coulomb excitation have been performed by taking full interaction into account:

Vector-potential term gives rise to magnetic interactions

1s2 1S0

1s 2p3/21P1

MJ =0

MJ =0 MJ =-1 MJ =+1

Alig

nmen

t par

amet

er A

2


( ) ( ) 2

3220

2e1

)(0

ii

fq qq

dqq ψβαψβ

σ µqr−

−∝ ∫

∞

MJ = -1 MJ = 0 MJ = +1

MJ = -1 MJ = 0 MJ = +1

A.S., U. Jentschura, S. Fritzsche and Th. Stöhlker, PRA 77 (2008) 042722




θ

Coulomb excitation Dielectronic recombinationRadiative electron capture

1stst

ep2n

dst

ep

Radiative decay following K-LL DR

K-LL DR of (initially) H-like U91+

Angular analysis of the characteristic radiation has been performed both the hypersatellite (HS) and satellite (S) transitions.

Discrepancy has been found for the anisotropy of the Kα1 HS line following K-L1/2L3/2 DR.

X. Ma et al., PRA 68 (2003) 042712

2s1/2 2p3/2 : 22p1/2 2p3/2 : 12p1/2 2p3/2 : 22s1/2 2p3/2 : 1

1s1/2 2p3/2 : 11s1/2 2p3/2 : 21s1/2 2p1/2 : 01s1/2 2s1/2 : 01s1/2 2p1/2 : 11s1/2 2s1/2 : 1

L 1/2

L 3/2

reso

nanc

e gr

oup

Kα1,2 HSnon-dipole effects were not included!


Radiative decay following K-LL DRDetailed theoretical analysis has been performed for each individual line by taking into account multipole-mixing and many-body phenomena.)(cosP1)( 222 θθ AfW +∝

Photon angular distribution:

alignmentstructure function

2s 2p3/2: 2 1s 2s: 1 2s 2p3/2: 1 1s 2s: 1

electric dipole (E1)all multipoles

...12

1~ 22 ++EM

f ifα

S. Fritzsche, A.S. and N. Kabachnik., PRA 78 (2008) 032703



Detailed theoretical analysis has been performed both for every individual line by taking into account multipole-mixing and many-body phenomena...

...and for resulting Kα1,2 radiation.

2s1/2 2p3/2 : 22p1/2 2p3/2 : 12p1/2 2p3/2 : 22s1/2 2p3/2 : 1

1s1/2 2p3/2 : 11s1/2 2p3/2 : 21s1/2 2p1/2 : 01s1/2 2s1/2 : 01s1/2 2p1/2 : 11s1/2 2s1/2 : 1

L 1/2

L 3/2

reso

nanc

e gr

oup

Kα1,2 HS

...))(cosP1()( 2)(

22,1++∝ ∑ θβθα

k

kkK NW

+ + .... =

2s 2p3/2: 2 1s 2s: 1 2s 2p3/2: 1 1s 2s: 1 all multipolesE1 only

S. Fritzsche, A.S. and N. Kabachnik., PRA 78 (2008) 032703



DR/RTE provides a tool to investigate magnetic (Breit) terms in the electron-electron interaction.

Strong effect was found for the resonant strengths (total cross section).

What is the effect for differential properties which are more sensitive to magnetic interactions?



We have investigated effect of Breit interaction on the population of doubly-excited ionic states and, hence, on the subsequent decay radiation.

( )( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛∇∇+−+

=+=

122

122211

12

1221

12

coscos

1

rr

rr

rVVV BC

ee

ωωααωααK-LL DR of (initially) H-like U91+

Example: alignment of 2s 2p1/2 : 1 level is strongly affected by Breit interaction effects.

2s 2p1/2: 1 1s 2s: 0

only CoulombCoulomb + Breit

Breit interaction strongly affects angular distribution of the subsequent decay!

only Coulomb Coulomb + Breit

MJ = -1 MJ = 0 MJ = +1

A2 = -0.516MJ = -1 MJ = 0 MJ = +1

A2 = +0.374

S. Fritzsche and A.S., PRA to be submitted



We have investigated effect of Breit interaction on the population of doubly-excited ionic states and, hence, on the subsequent decay radiation.

( )( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛∇∇+−+

=+=

122

122211

12

1221

12

coscos

1

rr

rr

rVVV BC

ee

ωωααωααK-LL DR of (initially) H-like U91+

Example: alignment of 2s 2p1/2 : 1 level is strongly affected by Breit interaction effects.

2s 2p1/2: 1 1s 2s: 0

only CoulombCoulomb + Breit

.... and its linear polarization!

only Coulomb Coulomb + Breit

MJ = -1 MJ = 0 MJ = +1

A2 = -0.516MJ = -1 MJ = 0 MJ = +1

A2 = +0.374

S. Fritzsche and A.S., PRA to be submitted



We discussed the characteristic x-ray emission from highly-charge ions following:


The angle-and polarization-resolved studies may reveal unique information about:

interplay of many-body and multipole-mixing effects

magnetic interactions in electron-nucleus and electron-electron interactions

dynamics of relativistic ion-atom collisions


polarization and correlation phenomena in relativistic ......projectile x-ray emission following...

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